@article{garcia_kim_vinod_sahoo_wax_kim_fang_narayanaswamy_wu_jiang_2024, title={Carbon nanofibers/liquid metal composites for high temperature laser ultrasound}, volume={138}, ISSN={["1874-9968"]}, url={https://doi.org/10.1016/j.ultras.2024.107245}, DOI={10.1016/j.ultras.2024.107245}, abstractNote={As the demand for clean energy becomes greater worldwide, there will also be an increasing demand for next generation nuclear power plants that incorporate advanced sensors and monitoring equipment. A major challenge posed by nuclear power plants is that, during normal operation, the reactor compartment is subjected to high operating temperatures and radiation flux. Diagnostic sensors monitoring such structures are also subject to temperatures reaching hundreds of degrees Celsius, which puts them at risk for heat degradation. In this work, the ability of carbon nanofibers to work in conjunction with a liquid metal as a photoacoustic transmitter was demonstrated at high temperatures. Fields metal, a Bi-In-Sn eutectic, and gallium are compared as acoustic mediums. Fields metal was shown experimentally to have superior performance over gallium and other reference cases. Under stimulation from a low fluence 6 ns pulse laser at 6 mJ/cm2 with 532 nm green light, the Fields metal transducer transmitted a 200 kHz longitudinal wave with amplitude >5.5 times that generated by a gallium transducer at 300 °C. Each high temperature test was conducted from a hot to cold progression, beginning as high as 300 °C, and then cooling down to 100 °C. Each test shows increasing signal amplitude of the liquid metal transducers as temperature decreases. Carbon nanofibers show a strong improvement over previously used candle-soot nanoparticles in both their ability to produce strong acoustic signals and absorb higher laser fluences up to 12 mJ/cm2.}, journal={ULTRASONICS}, author={Garcia, Nicholas and Kim, Howuk and Vinod, Kaushik and Sahoo, Abinash and Wax, Michael and Kim, Taeyang and Fang, Tiegang and Narayanaswamy, Venkat and Wu, Huaiyu and Jiang, Xiaoning}, year={2024}, month={Mar} }
 @article{yamashita_yamagata_xiang_maiwa_xu_jiang_2024, title={Comparison of field-cooling DC poling and AC poling for lead perovskite relaxor-PbTiO<sub>3</sub> single crystals grown by a continuous feeding Bridgman process}, volume={63}, ISSN={["1347-4065"]}, DOI={10.35848/1347-4065/ad2fe0}, abstractNote={Abstract We investigated the effectiveness of poling processes for Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals (SCs) produced using the continuous feeding Bridgman method that is known with a high property uniformity. The studied four poling processes are: (I) DC poling (DCP), (II) low voltage field cooling DCP (LV-FCP), (III) high voltage field cooling DCP (HV- FCP), and (IV) mid temperature AC poling (MT-ACP). The highest free dielectric constant (ε33T/ε0) and piezoelectric constant (d33) were obtained by the MT-ACP (ε33T/ε0 = 11000, d33 = 3000 pC/N), followed by LV-FCP (ε33T/ε0 = 7500, d33 = 2400 pC/N), HV-FCP (ε33T/ε0 = 6250, d33 = 1850 pC/N), and DCP (ε33T/ε0 = 6200, d33 = 1800 pC/N). The LV-FCP SC showed a 21% and 33% increase in ε33T/ε0 and d33 compared to those of DCP SC, however, not as much as the 77% and 67% improvement of the MT-ACP SC. These results provide a guidance for SC transducers.}, number={4}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS}, author={Yamashita, Yohachi and Yamagata, Yushi and Xiang, Yu and Maiwa, Hiroshi and Xu, Zhengze and Jiang, Xiaoning}, year={2024}, month={Apr} }
 @article{kreager_wu_chang_moon_mitchell_peng_huang_muller_tian_jiang_2024, title={High-Performance PMN-PT Single-Crystal-Based 1-3 Composite Transducer Integrated with a Biopsy Needle}, volume={14}, ISSN={["2079-6374"]}, DOI={10.3390/bios14020074}, abstractNote={To address the need for high-resolution imaging in lung nodule detection and overcome the limitations of the shallow imaging depth associated with high-frequency ultrasound and the complex structure of lung tissue, we successfully integrated 50 MHz ultrasound transducers with 18-gauge biopsy needles. Featuring a miniaturized size of 0.6 × 0.5 × 0.5 mm3, the 50 MHz micromachined 1-3 composite transducer was tested to perform mechanical scanning of a nodule within a lung-tissue-mimicking phantom in vitro. The high-frequency transducer demonstrated the ability to achieve imaging with an axial resolution of 30 μm for measuring nodule edges. Moreover, the integrated biopsy needle prototype exhibited high accuracy (1.74% discrepancy) in estimating nodule area compared to actual dimensions in vitro. These results underscore the promising potential of biopsy-needle-integrated transducers in enhancing the accuracy of endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNA) for clinical applications.}, number={2}, journal={BIOSENSORS-BASEL}, author={Kreager, Benjamin C. and Wu, Huaiyu and Chang, Wei-Yi and Moon, Sunho and Mitchell, Josh and Peng, Chang and Huang, Chih-Chung and Muller, Marie and Tian, Jian and Jiang, Xiaoning}, year={2024}, month={Feb} }
 @article{li_jin_jiang_an_ji_huang_2024, title={Influence of reaction cell electrodes on organic electrochemical transistors}, volume={124}, ISSN={["1077-3118"]}, DOI={10.1063/5.0176349}, abstractNote={Organic electrochemical transistors (OECTs) hold great potential in various applications, including biosensing and neural network computation. Traditional “all-in-one” OECT device architecture faces the problems of unclear amplification mechanisms and complex side reactions, to name a few. The reaction cell OECT (RC-OECT) device architecture, proposed by Ting et al. [Adv. Funct. Mater. 31(19), 2010868 (2021)], effectively resolves these problems. Furthermore, in many applications of OECTs, such as high throughput (bio)sensing, an OECT device array instead of a single OECT is needed. Therefore, the size (area) of the OECT device, which represents the amount of occupied chip real estate and the integration of the device, matters. In this paper, we developed a hydrogen peroxide sensor based on the RC-OECT. We utilized an RC cathode modified by the poly(3,4-ethylenedioxythiophene) polystyrene sulfonate film and a Ag/AgCl OECT gate electrode for facilitating device integration, varied RC anode area, and achieved optimization of at least one of the two parameters, sensitivity and lower limit of detection (LLoD), in conjunction with the level of integration of the device. Multiple quantitative sensitivity metrics have been adopted in this work. We also evaluated the correlation between RC anode area and LLoD. In addition, a mechanistic analysis of the RC-OECT device structure, in terms of faradic and non-faradaic currents, was carried out to illustrate the interplay between sensing performance and the electrode area of the reaction cell. This mechanistic analysis provides insights for miniaturizing OECT devices with the RC-OECT architecture.}, number={9}, journal={APPLIED PHYSICS LETTERS}, author={Li, Huiyuan and Jin, Zichen and Jiang, Xiaoning and An, Meiwen and Ji, Jianlong and Huang, Di}, year={2024}, month={Feb} }
 @article{wang_hou_xie_peng_li_zhao_zhang_jiang_yu_2024, title={Shear Horizontal Guided Wave Sensors Based on CTGS Piezoelectric Crystal for High-Temperature Structural Health Monitoring}, ISSN={["2199-160X"]}, DOI={10.1002/aelm.202300851}, abstractNote={Abstract}, journal={ADVANCED ELECTRONIC MATERIALS}, author={Wang, Guoliang and Hou, Shuai and Xie, Linfang and Peng, Xiangkang and Li, Yanlu and Zhao, Xian and Zhang, Shujun and Jiang, Xiaoning and Yu, Fapeng}, year={2024}, month={Mar} }
 @article{garcia_kim_vinod_kim_fang_jiang_2023, title={A Bi-In-Sn eutectic multi-layer high temperature ultrasound transmitter with candle-soot nanoparticles for improved photoacoustic efficiency}, volume={12487}, ISBN={["978-1-5106-6081-6"]}, ISSN={["1996-756X"]}, DOI={10.1117/12.2658480}, abstractNote={There is a growing need for non-invasive structural health monitoring in extreme environments. For nuclear power plants, pressure and temperature sensing under hazardous environment plays an important role for coolant system safety and stability management. Current sensing methods are intrusive, and suffer from degradation in the plant environment, limited life cycle, and complicated repair and replacement procedures. In this paper, we present an advanced Bi-In-Sn liquid metal (LM) transducer with the addition of candle-soot nanoparticles (CSNP) for improved photoacoustic efficiency and a metallic stencil for control of the liquid metal layer thickness. The sensitivity of the liquid metal candle-soot nanoparticle (LM-CSNP) ultrasound transmitter was characterized under 2 mJ/cm2 at 65 °C, and 6 mJ/cm2 at 100 °C —300 °C. Compared with existing LM transmitter, the newly presented transmitter showed a sensitivity 6.6 times stronger than previously reported LM only transmitter.}, journal={NONDESTRUCTIVE CHARACTERIZATION AND MONITORING OF ADVANCED MATERIALS, AEROSPACE, CIVIL INFRASTRUCTURE, AND TRANSPORTATION XVII}, author={Garcia, Nicholas and Kim, Ho-Wuk and Vinod, Kaushik and Kim, Taeyang and Fang, Tiegang and Jiang, Xiaoning}, year={2023} }
 @article{zhang_wu_kim_welch_cornett_stocker_nogueira_kim_owens_dayton_et al._2023, title={A Model of High-Speed Endovascular Sonothrombolysis with Vortex Ultrasound-Induced Shear Stress to Treat Cerebral Venous Sinus Thrombosis}, volume={6}, ISSN={["2639-5274"]}, DOI={10.34133/research.0048}, abstractNote={This research aims to demonstrate a novel vortex ultrasound enabled endovascular thrombolysis method designed for treating cerebral venous sinus thrombosis (CVST). This is a topic of substantial importance since current treatment modalities for CVST still fail in as many as 20% to 40% of the cases, and the incidence of CVST has increased since the outbreak of the coronavirus disease 2019 pandemic. Compared with conventional anticoagulant or thrombolytic drugs, sonothrombolysis has the potential to remarkably shorten the required treatment time owing to the direct clot targeting with acoustic waves. However, previously reported strategies for sonothrombolysis have not demonstrated clinically meaningful outcomes (e.g., recanalization within 30 min) in treating large, completely occluded veins or arteries. Here, we demonstrated a new vortex ultrasound technique for endovascular sonothrombolysis utilizing wave-matter interaction-induced shear stress to enhance the lytic rate substantially. Our in vitro experiment showed that the lytic rate was increased by at least 64.3% compared with the nonvortex endovascular ultrasound treatment. A 3.1-g, 7.5-cm-long, completely occluded in vitro 3-dimensional model of acute CVST was fully recanalized within 8 min with a record-high lytic rate of 237.5 mg/min for acute bovine clot in vitro. Furthermore, we confirmed that the vortex ultrasound causes no vessel wall damage over ex vivo canine veins. This vortex ultrasound thrombolysis technique potentially presents a new life-saving tool for severe CVST cases that cannot be efficaciously treated using existing therapies.}, journal={RESEARCH}, author={Zhang, Bohua and Wu, Huaiyu and Kim, Howuk and Welch, Phoebe J. and Cornett, Ashley and Stocker, Greyson and Nogueira, Raul G. and Kim, Jinwook and Owens, Gabe and Dayton, Paul A. and et al.}, year={2023}, month={Jan}, pages={1–13} }
 @misc{bautista_kim_xu_jiang_dayton_2023, title={Current Status of Sub-micron Cavitation-Enhancing Agents for Sonothrombolysis}, volume={49}, ISSN={["1879-291X"]}, DOI={10.1016/j.ultrasmedbio.2023.01.018}, abstractNote={Thrombosis in cardiovascular disease is an urgent global issue, but treatment progress is limited by the risks of current antithrombotic approaches. The cavitation effect in ultrasound-mediated thrombolysis offers a promising mechanical alternative for clot lysis. Further addition of microbubble contrast agents introduces artificial cavitation nuclei that can enhance the mechanical disruption induced by ultrasound. Recent studies have proposed sub-micron particles as novel sonothrombolysis agents with increased spatial specificity, safety and stability for thrombus disruption. In this article, the applications of different sub-micron particles for sonothrombolysis are discussed. Also reviewed are in vitro and in vivo studies that apply these particles as cavitation agents and as adjuvants to thrombolytic drugs. Finally, perspectives on future developments in sub-micron agents for cavitation-enhanced sonothrombolysis are shared. Thrombosis in cardiovascular disease is an urgent global issue, but treatment progress is limited by the risks of current antithrombotic approaches. The cavitation effect in ultrasound-mediated thrombolysis offers a promising mechanical alternative for clot lysis. Further addition of microbubble contrast agents introduces artificial cavitation nuclei that can enhance the mechanical disruption induced by ultrasound. Recent studies have proposed sub-micron particles as novel sonothrombolysis agents with increased spatial specificity, safety and stability for thrombus disruption. In this article, the applications of different sub-micron particles for sonothrombolysis are discussed. Also reviewed are in vitro and in vivo studies that apply these particles as cavitation agents and as adjuvants to thrombolytic drugs. Finally, perspectives on future developments in sub-micron agents for cavitation-enhanced sonothrombolysis are shared.}, number={5}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Bautista, Kathlyne Jayne B. and Kim, Jinwook and Xu, Zhen and Jiang, Xiaoning and Dayton, Paul A.}, year={2023}, month={May}, pages={1049–1057} }
 @article{xue_zhang_moon_xu_huang_sharma_jiang_2023, title={Development of a Wearable Ultrasound Transducer for Sensing Muscle Activities in Assistive Robotics Applications}, volume={13}, ISSN={["2079-6374"]}, url={https://doi.org/10.3390/bios13010134}, DOI={10.3390/bios13010134}, abstractNote={Robotic prostheses and powered exoskeletons are novel assistive robotic devices for modern medicine. Muscle activity sensing plays an important role in controlling assistive robotics devices. Most devices measure the surface electromyography (sEMG) signal for myoelectric control. However, sEMG is an integrated signal from muscle activities. It is difficult to sense muscle movements in specific small regions, particularly at different depths. Alternatively, traditional ultrasound imaging has recently been proposed to monitor muscle activity due to its ability to directly visualize superficial and at-depth muscles. Despite their advantages, traditional ultrasound probes lack wearability. In this paper, a wearable ultrasound (US) transducer, based on lead zirconate titanate (PZT) and a polyimide substrate, was developed for a muscle activity sensing demonstration. The fabricated PZT-5A elements were arranged into a 4 × 4 array and then packaged in polydimethylsiloxane (PDMS). In vitro porcine tissue experiments were carried out by generating the muscle activities artificially, and the muscle movements were detected by the proposed wearable US transducer via muscle movement imaging. Experimental results showed that all 16 elements had very similar acoustic behaviors: the averaged central frequency, −6 dB bandwidth, and electrical impedance in water were 10.59 MHz, 37.69%, and 78.41 Ω, respectively. The in vitro study successfully demonstrated the capability of monitoring local muscle activity using the prototyped wearable transducer. The findings indicate that ultrasonic sensing may be an alternative to standardize myoelectric control for assistive robotics applications.}, number={1}, journal={BIOSENSORS-BASEL}, author={Xue, Xiangming and Zhang, Bohua and Moon, Sunho and Xu, Guo-Xuan and Huang, Chih-Chung and Sharma, Nitin and Jiang, Xiaoning}, year={2023}, month={Jan} }
 @article{yamashita_sun_xiang_maiwa_lee_kim_jiang_2023, title={Enhanced electrical properties by AC poling of relaxor-Pb(Zr,Ti)O-3 single crystals manufactured by the solid state crystal growth method}, volume={62}, ISSN={["1347-4065"]}, DOI={10.35848/1347-4065/ace537}, abstractNote={Abstract}, number={SM}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS}, author={Yamashita, Yohachi John and Sun, Haiyang and Xiang, Yu and Maiwa, Hiroshi and Lee, Ho-Yong and Kim, Hwang-Pill and Jiang, Xiaoning}, year={2023}, month={Nov} }
 @article{rayes_zhang_lu_qian_schroff_ryu_jiang_zhou_2023, title={Estimating Thrombus Elasticity by Shear Wave Elastography to Evaluate Ultrasound Thrombolysis for Thrombus With Different Stiffness}, volume={70}, ISSN={["1558-2531"]}, DOI={10.1109/TBME.2022.3186586}, abstractNote={Objective: There is uncertainty about deep vein thrombosis standard treatment as thrombus stiffness alters each case. Here, we investigated thrombus’ stiffness of different compositions and ages using shear wave elastography (SWE). We then studied the effectiveness of ultrasound-thrombolysis on different thrombus compositions. Methods: Shear waves generated through mechanical shaker and traveled along thrombus of different hematocrit (HCT) levels, whereas 18-MHz ultrasound array used to detect wave propagation. Thrombus’ stiffness was identified by the shear wave speed (SWS). In thrombolysis, a 3.2 MHz focused transducer was applied to different thrombus compositions using different powers. The thrombolysis rate was defined as the percentage of weight loss. Results: The estimated average SWS of 20%, 40%, and 60% HCT thrombus were 0.75 m/s, 0.44 m/s, and 0.32 m/s, respectively. For Thrombolysis, the percentage weight loss at 8 MPa Negative pressure for the same HCT groups were 23.1%, 35.29%, and 39.66% respectively. Conclusion: SWS is inversely related to HCT level and positively related to thrombus age. High HCT thrombus had higher weight loss compared to low HCT. However, the difference between 20% and 40% HCT was more significant than between 40% and 60% HCT in both studies. Our results suggest that thrombus with higher SWS require more power to achieve the same thrombolysis rate as thrombus with lower SWS. Significance: Characterizing thrombus elastic property undergoing thrombolysis enables evaluation of ultrasound efficacy for fractionating thrombus and reveals the appropriate ultrasound parameters selection to achieve a certain thrombolysis rate in the case of a specific thrombus stiffness.}, number={1}, journal={IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING}, author={Rayes, Adnan and Zhang, Junhang and Lu, Gengxi and Qian, Xuejun and Schroff, Stuart T. T. and Ryu, Robert and Jiang, Xiaoning and Zhou, Qifa}, year={2023}, month={Jan}, pages={135–143} }
 @article{negi_kim_hua_timofeeva_zhang_zhu_peters_kumah_jiang_liu_2023, title={Ferroelectric Domain Wall Engineering Enables Thermal Modulation in PMN-PT Single Crystals}, volume={4}, ISSN={["1521-4095"]}, url={https://doi.org/10.1002/adma.202211286}, DOI={10.1002/adma.202211286}, abstractNote={Abstract}, journal={ADVANCED MATERIALS}, author={Negi, Ankit and Kim, Hwang Pill and Hua, Zilong and Timofeeva, Anastasia and Zhang, Xuanyi and Zhu, Yong and Peters, Kara and Kumah, Divine and Jiang, Xiaoning and Liu, Jun}, year={2023}, month={Apr} }
 @article{cai_hu_chen_prieto_rosenbaum_stringer_jiang_2023, title={Inertial Measurement Unit-Assisted Ultrasonic Tracking System for Ultrasound Probe Localization}, volume={70}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2022.3207185}, abstractNote={Ultrasonic tracking is a promising technique in indoor object localization. However, limited success has been reported in dynamic orientational and positional ultrasonic tracking for ultrasound (US) probes due to its instability and relatively low accuracy. This article aims at developing an inertial measurement unit (IMU)-assisted ultrasonic tracking system that enables a high accuracy positional and orientational localization. The system was designed with the acoustic pressure field simulation of the transmitter, receiver configuration, position-variant error simulation, and sensor fusion. The prototype was tested in a tracking volume required in typical obstetric sonography within the typical operation speed ranges (slow mode and fast mode) of US probe movement. The performance in two different speed ranges was evaluated against a commercial optical tracking device. The results show that the proposed IMU-assisted US tracking system achieved centimeter-level positional tracking accuracy with the mean absolute error (MAE) of 12 mm and the MAE of orientational tracking was less than 1°. The results indicate the possibility of implementing the IMU-assisted ultrasonic tracking system in US probe localization.}, number={9}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Cai, Qianqian and Hu, Jiale and Chen, Mengyue and Prieto, Juan and Rosenbaum, Alan J. and Stringer, Jeffrey S. A. and Jiang, Xiaoning}, year={2023}, month={Sep}, pages={920–929} }
 @article{kim_wu_chen_dai_zhou_jiang_2023, title={Intravascular Sono-Ablation for In-Stent Restenosis Relief: Transducer Development and the In-Vitro Demonstration}, volume={70}, ISSN={["1558-2531"]}, DOI={10.1109/TBME.2023.3238679}, abstractNote={Objective: This study aimed to propose a new clinical modality for the relief of in-stent restenosis (ISR) using focused ultrasound (FUS) ablation. In the first research stage, a miniaturized FUS device was developed for the sonification of the remaining plaque after stenting, known as one of the causes of ISR. Methods: This study presents a miniaturized (<2.8 mm) intravascular FUS transducer for ISR treatment. The performance of the transducer was predicted through a structural-acoustic simulation, followed by fabrication of the prototype device. Using the prototype FUS transducer, we demonstrated tissue ablation with bio-tissues over metallic stents, mimicking in-stent tissue ablation. Next, we conducted a safety test by detecting the existence of thermal damage to the arterial tissue upon sonication with a controlled dose. Results: The prototype device successfully delivered sufficient acoustic intensity (>30 W/cm2) to a bio tissue (chicken breast) through a metallic stent. The ablation volume was approximately 3.9 × 7.8 × 2.6 mm3. Furthermore, 1.5 min sonication was sufficient to obtain an ablating depth of approximately 1.0 mm, not thermally damaging the underlying artery vessel. Conclusion: We demonstrated in-stent tissue sonoablation, suggesting it could be as a future ISR treatment modality. Significance: Comprehensive test results provide a key understanding of FUS applications using metallic stents. Furthermore, the developed device can be used for sonoablation of the remaining plaque, providing a novel approach to the treatment of ISR.}, number={7}, journal={IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING}, author={Kim, Howuk and Wu, Huaiyu and Chen, Mengyue and Dai, Xuming and Zhou, Ruihai and Jiang, Xiaoning}, year={2023}, month={Jul}, pages={2172–2180} }
 @article{wu_kreager_chen_zhang_abenojar_exner_jiang_2023, title={Intravascular sonothrombolysis with nanobubbles : <i>in</i>-<i>vitro</i> study}, ISSN={["1944-9380"]}, DOI={10.1109/NANO58406.2023.10231295}, abstractNote={Thrombosis-related morbidity and mortality pose a significant global health challenge. Existing approaches for thrombolysis, such as administering fibrinolytic agents or performing mechanical thrombectomy, come with prolonged treatment duration and risks of complications. Recent research proposes a more effective and safer alternative with contrast agents mediated ultrasound thrombolysis. Nonetheless, effectively treating retracted clots remains problematic due to their dense structure. To tackle this issue, we introduce an innovative method utilizing a stacked transducer for intravascular sonothrombolysis for higher lysis efficiency, employing a mixture of nanobubbles (NB) and microbubbles (MB). The inclusion of nanobubbles serves to enhance cavitation and improve the breakdown of clot structures. In our study, we employed a 470 kHz transducer with an aperture size of $1.4\times 1.4$ mm2 integrated in a 9-Fr catheter. Preliminary results indicate that NB- and MB/NB-mediated sonothrombolysis led to a 31% and 65% higher lysis rate, respectively, compared to MB-mediated sonothrombolysis in the case of retracted clots. These findings demonstrate the significant potential of nanobubbles in the field of sonothrombolysis applications.}, journal={2023 IEEE 23RD INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY, NANO}, author={Wu, Huaiyu and Kreager, Ben and Chen, Mengyue and Zhang, Bohua and Abenojar, Eric and Exner, Agata A. and Jiang, Xiaoning}, year={2023}, pages={376–379} }
 @article{kreager_moon_mitchell_wu_peng_muller_huang_jiang_2023, title={Lung nodule biopsy guided using a 30 MHz ultrasound transducer: in vitro study}, volume={12488}, ISBN={["978-1-5106-6083-0"]}, ISSN={["1996-756X"]}, DOI={10.1117/12.2658585}, abstractNote={Ultrasound is often favored in biopsy guidance since it is non-ionizing, inexpensive, portable, and has a high frame rate. However, imaging probes that operate at a low frequency may not be able to differentiate between tiny targets and surrounding tissues clearly, and at a high frequency, it suffers from tissue scattering and signals attenuation, which is hard to image deeper targets such as lung tissues. In this study, we developed a biopsy needle (with a size of 18 G) integrated with a 30 MHz high-frequency ultrasound transducer (axial resolution: ~ 100 µm) for the lung nodule biopsy in vitro test. To mimic contrasting biological tissues, a melamine foam-gelatin phantom was developed. With an advancing step of 0.5 mm, the distance from the biopsy needle to the gelatin-foam boundary was estimated by the speed of sound in gelatin and the time-of-flight of the echo signal. The results showed that the 30 MHz ultrasound transducer can map the geometry of the gelatin-foam boundary, indicating the capability of distinguishing tumor and healthy lung tissue with this ultrasound-guided biopsy technique.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS XVII}, author={Kreager, Ben and Moon, Sunho and Mitchell, Josh and Wu, Huaiyu and Peng, Chang and Muller, Marie and Huang, Chih-Chung and Jiang, Xiaoning}, year={2023} }
 @misc{zhang_jiang_2023, title={Magnetic Nanoparticles Mediated Thrombolysis-A Review}, volume={4}, ISSN={["2644-1292"]}, DOI={10.1109/OJNANO.2023.3273921}, abstractNote={Nanoparticles containing thrombolytic medicines have been developed for thrombolysis applications in response to the increasing demand for effective, targeted treatment of thrombosis disease. In recent years, there has been a great deal of interest in nanoparticles that can be navigated and driven by a magnetic field. However, there are few review publications concerning the application of magnetic nanoparticles in thrombolysis. In this study, we examine the current state of magnetic nanoparticles in the application of in vitro and in vivo thrombolysis under a static or dynamic magnetic field, as well as the combination of magnetic nanoparticles with an acoustic field for dual-mode thrombolysis. We also discuss four primary processes of magnetic nanoparticles mediated thrombolysis, including magnetic nanoparticle targeting, magnetic nanoparticle trapping, magnetic drug release, and magnetic rupture of blood clot fibrin networks. This review will offer unique insights for the future study and clinical development of magnetic nanoparticles mediated thrombolysis approaches.}, journal={IEEE OPEN JOURNAL OF NANOTECHNOLOGY}, author={Zhang, Bohua and Jiang, Xiaoning}, year={2023}, pages={109–132} }
 @article{wu_tang_zhang_klippel_jing_yao_jiang_2023, title={Miniaturized Stacked Transducer for Intravascular Sonothrombolysis With Internal-Illumination Photoacoustic Imaging Guidance and Clot Characterization}, volume={70}, ISSN={["1558-2531"]}, url={https://doi.org/10.1109/TBME.2023.3240725}, DOI={10.1109/TBME.2023.3240725}, abstractNote={Thromboembolism in blood vessels can lead to stroke or heart attack and even sudden death unless brought under control. Sonothrombolysis enhanced by ultrasound contrast agents has shown promising outcome on effective treatment of thromboembolism. Intravascular sonothrombolysis was also reported recently with a potential for effective and safe treatment of deep thrombosis. Despite the promising treatment results, the treatment efficiency for clinical application may not be optimized due to the lack of imaging guidance and clot characterization during the thrombolysis procedure. In this paper, a miniaturized transducer was designed to have an 8-layer PZT-5A stacked with an aperture size of 1.4 × 1.4 mm2 and assembled in a customized two-lumen 10-Fr catheter for intravascular sonothrombolysis. The treatment process was monitored with internal-illumination photoacoustic tomography (II-PAT), a hybrid imaging modality that combines the rich contrast of optical absorption and the deep penetration of ultrasound detection. With intravascular light delivery using a thin optical fiber integrated with the intravascular catheter, II-PAT overcomes the penetration depth limited by strong optical attenuation of tissue. In-vitro PAT-guided sonothrombolysis experiments were carried out with synthetic blood clots embedded in tissue phantom. Clot position, shape, stiffness, and oxygenation level can be estimated by II-PAT at clinically relevant depth of ten centimeters. Our findings have demonstrated the feasibility of the proposed PAT-guided intravascular sonothrombolysis with real-time feedback during the treatment process.}, number={8}, journal={IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING}, author={Wu, Huaiyu and Tang, Yuqi and Zhang, Bohua and Klippel, Paul and Jing, Yun and Yao, Junjie and Jiang, Xiaoning}, year={2023}, month={Aug}, pages={2279–2288} }
 @article{peng_wu_jiang_2023, title={Nanotechnology-Enabled Ultrasound Transducers}, ISSN={["1942-7808"]}, DOI={10.1109/MNANO.2023.3297117}, abstractNote={Ultrasound transducer is a core component for transductions between acoustic energy and electrical energy in numerous applications including medical imaging, therapy, human health monitoring and non-destructive testing (NDT). The rapid advancement of nanotechnology in recent years has opened up new prospects for ultrasound transducers. The integration of nanomaterials and nanofabrication techniques with ultrasound transducers offers ample opportunities for enhancing transducer performances and opening up new applications. The objective of this review is to provide the state-of-the-art advancement of nanotechnology-enabled ultrasound transducers, with a focus on nanomaterials applied in both piezoelectric transducers and optoacoustic transducers, as well as fabrication techniques of nanostructured materials for ultrasound transducers. Firstly, nanomaterials and nanofabrication techniques for both piezoelectric transducers and optoacoustic transducers are reviewed and summarized. Representative nanotechnology-enabled ultrasound transducers for biomedical and NDT applications are then examined. Finally, a discussion of major challenges and future research directions of nanotechnology-enabled ultrasound transducers are presented.}, journal={IEEE NANOTECHNOLOGY MAGAZINE}, author={Peng, Chang and Wu, Huaiyu and Jiang, Xiaoning}, year={2023}, month={Aug} }
 @article{kim_balagopal_kerrigan_garcia_chow_bourham_fang_jiang_2023, title={Noninvasive liquid level sensing with laser generated ultrasonic waves}, volume={130}, ISSN={0041-624X}, url={http://dx.doi.org/10.1016/j.ultras.2023.106926}, DOI={10.1016/j.ultras.2023.106926}, abstractNote={This article proposes a noninvasive liquid level sensing technique using laser-generated ultrasound waves for nuclear power plant applications. Liquid level sensors play an important role of managing the coolant system safely and stably in the plant structure. Current sensing techniques are mostly intrusive, performing inside the fluidic structure, which is disadvantageous in terms of the regular maintenance of the plant system. Furthermore, typical intrusive sensors do not perform stably under varying environmental conditions such as temperature and radiation. In this study, sensing units are attached to the outer surface of a liquid vessel to capture guided ultrasound waves in a nonintrusive manner. The signal intensity of the guided wave dissipates when the signal interacts with the internal liquid media. The sensing mechanism is mathematically expressed as an index value to correlate the liquid level with the sensor signal. For the acoustic wave generation, laser-generated ultrasound was adopted instead of using typical contact type transducers. Following the simulation validation of the proposed concept, the performance of the developed sensor was confirmed through experimental results under elevated liquid temperature conditions. The nonlinear multivariable regression exhibited the best-fit to the datasets measured under the variable liquid level and temperature conditions.}, journal={Ultrasonics}, publisher={Elsevier BV}, author={Kim, Howuk and Balagopal, Bharat and Kerrigan, Sean and Garcia, Nicholas and Chow, Mo-Yuen and Bourham, Mohamed and Fang, Tiegang and Jiang, Xiaoning}, year={2023}, month={Apr}, pages={106926} }
 @article{kim_jiang_2023, title={Numerical Study of a Miniaturized, 1-3 Piezoelectric Composite Focused Ultrasound Transducer}, volume={13}, ISSN={["2076-3417"]}, DOI={10.3390/app13010615}, abstractNote={This study aimed to develop an optimal methodology for the design of a miniaturized, 1–3 piezoelectric composite focused ultrasound transducer. Miniaturized focused ultrasound (FUS) devices, generally guided through catheters, have received considerable attention in the biomedical and ultrasound fields as they can overcome the technical restrictions of typical FUS transducers. However, miniaturized transducers cannot readily generate a high acoustic intensity because of their small aperture sizes and the vibration mode coupling. As such, 1–3 composite transducers, having a high electromechanical coupling and efficient vibration directivity, break through the current technical restrictions. However, the systematic methodology for designing miniaturized FUS transducers has not been thoroughly discussed so far. Therefore, in this study, we designed 1–3 piezoelectric composite transducers using analytical and numerical methods. Specifically, extensive parametric studies were performed through finite element analysis under the coupled field with piezoelectricity, structural vibration, and acoustic pressure. The simulation results confirmed that the optimal design of the 1–3 composite type transducer produces much higher (>160%) acoustic pressure output at the focal point than the single-phase device. Furthermore, the array type of the interstitial transducer was predicted to produce an unprecedented acoustic intensity of approximately 188 W/cm2 under a short duty cycle (1%). This study will provide valuable technical methodology for the development of interstitial, 1–3 composite FUS transducers and the selection of optimal design parameters.}, number={1}, journal={APPLIED SCIENCES-BASEL}, author={Kim, Howuk and Jiang, Xiaoning}, year={2023}, month={Jan} }
 @misc{he_wan_jiang_peng_2023, title={Piezoelectric Micromachined Ultrasound Transducer Technology: Recent Advances and Applications}, volume={13}, ISSN={["2079-6374"]}, DOI={10.3390/bios13010055}, abstractNote={The objective of this article is to review the recent advancement in piezoelectric micromachined ultrasound transducer (PMUT) technology and the associated piezoelectric materials, device fabrication and characterization, as well as applications. PMUT has been an active research topic since the late 1990s because of the ultrasound application needs of low cost large 2D arrays, and the promising progresses on piezoelectric thin films, semiconductors, and micro/nano-electromechanical system technology. However, the industrial and medical applications of PMUTs have not been very significant until the recent success of PMUT based fingerprint sensing, which inspired growing interests in PMUT research and development. In this paper, recent advances of piezoelectric materials for PMUTs are reviewed first by analyzing the material properties and their suitability for PMUTs. PMUT structures and the associated micromachining processes are next reviewed with a focus on the complementary metal oxide semiconductor compatibility. PMUT prototypes and their applications over the last decade are then summarized to show the development trend of PMUTs. Finally, the prospective future of PMUTs is discussed as well as the challenges on piezoelectric materials, micro/nanofabrication and device integration.}, number={1}, journal={BIOSENSORS-BASEL}, author={He, Yashuo and Wan, Haotian and Jiang, Xiaoning and Peng, Chang}, year={2023}, month={Jan} }
 @article{ji_wang_zhang_wang_niu_jiang_qiao_ren_zhang_sang_et al._2023, title={Pulse electrochemical synaptic transistor for supersensitive and ultrafast biosensors}, ISSN={["2567-3165"]}, DOI={10.1002/inf2.12478}, abstractNote={Abstract}, journal={INFOMAT}, author={Ji, Jianlong and Wang, Zhenxing and Zhang, Fan and Wang, Bin and Niu, Yan and Jiang, Xiaoning and Qiao, Zeng-ying and Ren, Tian-ling and Zhang, Wendong and Sang, Shengbo and et al.}, year={2023}, month={Aug} }
 @article{sheng_wei_chen_zhang_kim_geng_jiang_kim_2023, title={Quantitative characterization of the ultrasound thermal strains in tissue mimicking phantoms with different oil concentrations}, volume={153}, ISSN={["1520-8524"]}, DOI={10.1121/10.0019122}, abstractNote={Ultrasound thermal strain imaging (US-TSI) has been known for the capability of tissue characterization according to distinct sound speed change in different tissues when temperature increases. US-TSI for detecting lipids in atherosclerosis plaques and fatty livers has previously been reported while some practical challenges were not fully addressed, especially due to physiological motions. To overcome such limitation, we recently developed an ultrasound transducer that combines an acoustic heating array and an imaging array to achieve US-TSI with heating performed in a region of approximately 10 mm by 5 mm by 2 mm within a very short time period of about 50 ms compared both cardiac and breathing motions. To characterize the new US-TSI probe, a thorough benchtop investigation was performed on the relationship among the threekey variables for TSI: thermal strain, temperature increase, and lipid concentration. In the experiments, homogeneous oil-in-gelatin phantoms of different oil concentrations were fabricated to simulate different lipid-plaque concentrations. Temperature curves were recorded by a thermal couple with millisecond-level time constant. Thermal strains were computed by developed US-TSI signal processing procedures. The results build a tissue-temperature-strain model and calibrate the new US-TSI probe for in vivo atherosclerosis plaque characterization.}, number={3}, journal={JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA}, author={Sheng, Zhiyu and Wei, Ran and Chen, Mengyue and Zhang, Bohua and Kim, Howuk and Geng, Xuecang and Jiang, Xiaoning and Kim, Kang}, year={2023}, month={Mar} }
 @misc{kabakov_kim_cheng_jiang_zhang_2023, title={The Versatility of Piezoelectric Composites}, volume={53}, ISSN={["1545-4118"]}, DOI={10.1146/annurev-matsci-080921-092839}, abstractNote={ Piezoelectric materials possess the capability to interchangeably convert electrical energy into a mechanical response. While current piezoelectric materials exhibit strong properties, known limitations have inhibited further development. This review describes the ability to combine different piezoelectric materials into a composite to create well-rounded properties. The different types of connectivity classes are described as well as important design considerations and theoretical models. The contributions from the active and passive phases are outlined, focusing primarily on ferroelectric ceramics and polymer-based composites. The key advantage of piezoelectric composites is their ability to combine the flexibility of polymers with the high electromechanical coupling and piezoelectric coefficients of ferroelectric ceramics or single crystals appropriate for a variety of applications. Composites are prominent in medical ultrasound imaging and therapy, underwater acoustic sensing, industrial structural health monitoring, energy harvesting, and numerous other emerging applications. }, journal={ANNUAL REVIEW OF MATERIALS RESEARCH}, author={Kabakov, Peter and Kim, Taeyang and Cheng, Zhenxiang and Jiang, Xiaoning and Zhang, Shujun}, year={2023}, pages={165–193} }
 @article{kim_wan_lee_yamashita_jo_jiang_2023, title={Thermal stability studies of alternating current poled Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals grown by solid-state crystal growth}, volume={11}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2022.2161841}, abstractNote={Thermal stabilities of relaxor-PbTiO3 single crystals are of great importance due to their limited operational temperatures in devices. Herein, to elucidate how poling conditions influence thermal stabilities, we investigated direct current (DC) and alternating current (AC) poled Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-29PT) crystals grown by solid-state crystal growth, which guarantees more compositional uniformity. Our experiments show that the dielectric permittivity of the DC and AC poled crystals are 3560 and 4970, respectively, after annealing at 99.6°C, implying AC-poling prevails in enhancing thermal stabilities of relaxor-PbTiO3 single crystals. The mechanism behind the dissimilar thermal stabilities can be attributed to different domain configurations. GRAPHICAL ABSTRACT IMPACT STATEMENT Alternating-current poling is of useful for not only enhancing piezoelectric and dielectric properties but also improving the thermal stabilities of relaxor-PbTiO3 single crystals.}, number={5}, journal={MATERIALS RESEARCH LETTERS}, author={Kim, Hwang-Pill and Wan, Haotian and Lee, Ho-Yong and Yamashita, Yohachi and Jo, Wook and Jiang, Xiaoning}, year={2023}, month={May}, pages={383–390} }
 @article{negi_rodriguez_zhang_comstock_yang_sun_jiang_kumah_hu_liu_2023, title={Thickness-Dependent Thermal Conductivity and Phonon Mean Free Path Distribution in Single-Crystalline Barium Titanate}, volume={4}, ISSN={["2198-3844"]}, url={https://doi.org/10.1002/advs.202301273}, DOI={10.1002/advs.202301273}, abstractNote={Abstract}, journal={ADVANCED SCIENCE}, author={Negi, Ankit and Rodriguez, Alejandro and Zhang, Xuanyi and Comstock, Andrew H. H. and Yang, Cong and Sun, Dali and Jiang, Xiaoning and Kumah, Divine and Hu, Ming and Liu, Jun}, year={2023}, month={Apr} }
 @article{naderi_quoc-thai_zhuang_jiang_2023, title={Vibration Analysis of a Unimorph Nanobeam with a Dielectric Layer of Both Flexoelectricity and Piezoelectricity}, volume={16}, ISSN={["1996-1944"]}, DOI={10.3390/ma16093485}, abstractNote={In this study, for the first time, free and forced vibrational responses of a unimorph nanobeam consisting of a functionally graded base, along with a dielectric layer of both piezoelectricity and flexoelectricity, is investigated based on paradox-free local/nonlocal elasticity. The formulation and boundary conditions are attained by utilizing the energy method Hamilton’s principle. In order to set a comparison, the formulation of a model in the framework of differential nonlocal is first presented. An effective implementation of the generalized differential quadrature method (GDQM) is then utilized to solve higher-order partial differential equations. This method can be utilized to solve the complex equations whose analytic results are quite difficult to obtain. Lastly, the impact of various parameters is studied to characterize the vibrational behavior of the system. Additionally, the major impact of flexoelectricity compared to piezoelectricity on a small scale is exhibited. The results show that small-scale flexoelectricity, rather than piezoelectricity, is dominant in electromechanical coupling. One of the results that can be mentioned is that the beams with higher nonlocality have the higher voltage and displacement under the same excitation amplitude. The findings can be helpful for further theoretical as well as experimental studies in which dielectric material is used in smart structures.}, number={9}, journal={MATERIALS}, author={Naderi, Ali and Quoc-Thai, Tran and Zhuang, Xiaoying and Jiang, Xiaoning}, year={2023}, month={Apr} }
 @article{kim_zhang_wu_yao_shi_jiang_2023, title={Vortex-ultrasound for microbubble-mediated thrombolysis of retracted clots}, volume={123}, ISSN={["1077-3118"]}, DOI={10.1063/5.0155223}, abstractNote={Endovascular sonothrombolysis has gained significant attention due to its benefits, including direct targeting of the thrombus with sonication and reduced side effects. However, the small aperture of endovascular transducers restricts the improvement of their potential clinical efficiency due to inefficient acoustic radiation. Hence, in an earlier study, we used vortex ultrasound with an endovascular ultrasound transducer to induce shear stress and enhance the clot lysis. In this study, the vortex acoustic transduction mechanism was investigated using numerical simulations and hydrophone tests. Following this characterization, we demonstrated the performance of the vortex ultrasound transducer in thrombolysis of retracted clots in in vitro tests. The test results indicated that the maximum lysis rates were 79.0% and 32.2% with the vortex ultrasound for unretracted and retracted clots, respectively. The vortex ultrasound enhanced the efficiency of the thrombolysis by approximately 49%, both for retracted and unretracted clots, compared with the typical non-vortex ultrasound technique. Therefore, the use of endovascular vortex ultrasound holds promise as a potential clinical option for the thrombolysis of retracted clots.}, number={7}, journal={APPLIED PHYSICS LETTERS}, author={Kim, Howuk and Zhang, Bohua and Wu, Huaiyu and Yao, Junjie and Shi, Chengzhi and Jiang, Xiaoning}, year={2023}, month={Aug} }
 @article{wan_luo_kim_chung_chang_yamashita_jiang_2022, title={<p>The overpoling effect of alternating current poling on rhombohedral Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals</p>}, volume={120}, ISSN={["1077-3118"]}, DOI={10.1063/5.0086057}, abstractNote={The overpoling effect of alternating current poling (ACP) was studied on [001]-orientated rhombohedral Pb(Mg1/3Nb2/3)O3-0.26PbTiO3 (PMN-0.26PT) single crystals. Our experimental results showed that the property enhancement from the ACP was remarkable only when the poling cycle number (NL) was kept low. When ACP was continued after the saturation, dielectric and piezoelectric properties gradually dropped down to traditional direct current poled levels or even lower. Such a decrease in material properties caused by the large NL during ACP was defined as the “overpoling effect of ACP” in this study. The following lattice symmetry and domain structure characterization studies were performed through x-ray diffraction (XRD) and piezoelectric force microscopy (PFM) to find the origin of the overpoling effect. The XRD measurements combined with temperature dependence of dielectric properties demonstrated that the field-induced phase transition continued when the samples became overpoled. Further PFM measurements illustrated that the domain density of the overpoled ACP sample was significantly lower than that of the normal one, while the “2R” domain configuration was maintained through the ACP process. In addition, the hysteresis loop characterization indicated large decreases in the coercive fields. The discovered overpoling effect of ACP could help us understand the mechanisms of ACP and optimize the ACP process.}, number={19}, journal={APPLIED PHYSICS LETTERS}, author={Wan, Haotian and Luo, Chengtao and Kim, Hwang-Pill and Chung, Ching-Chang and Chang, Wei-Yi and Yamashita, Yohachi and Jiang, Xiaoning}, year={2022}, month={May} }
 @article{moon_wu_zhang_kim_dayton_xu_jiang_2022, title={A Dual-Frequency Intravascular Ultrasound Transducer for Amplified Nanodroplet Vaporization Effects in Cavitation-Enhanced Sonothrombolysis}, ISSN={["1948-5719"]}, DOI={10.1109/IUS54386.2022.9958578}, abstractNote={Thromboembolism often leads to stroke, myocardial infarction, and other severe complications. There remains a need for new technologies for clinical thrombosis treatment. Sonothrombolysis mediated with cavitation-enhancing agents has shown promise in the treatment of thromboembolism in preclinical studies and clinical trials. Recent works have emphasized specifically efficient sonothrombolysis using phase-change nanodroplets, likely due to their generation of cavitation within the clot matrix. Yet, it has also been reported that nanodroplets might vaporize more effectively under high-frequency excitation and generate more cavitation with low-frequency excitation. Therefore, in this work, a dual-frequency (10 MHz/500 kHz) intravascular transducer intended for nanodroplet-specific sonothrombolysis was developed to improve clot mass reduction rate while retaining lower acoustic pressures than the typical nanodroplet vaporization threshold at sub-megahertz excitation (> 5 MPa). It results in a 34 % improvement of thrombolysis efficiency compared to a single low-frequency excitation.}, journal={2022 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS)}, author={Moon, Sunho and Wu, Huaiyu and Zhang, Bohua and Kim, Jinwook and Dayton, Paul A. and Xu, Zhen and Jiang, Xiaoning}, year={2022} }
 @article{zhang_wu_jiang_2022, title={A Laser-Coupled Dual Excitation Intravascular Ultrasound Transducer for Sonothrombolysis}, ISSN={["2378-377X"]}, DOI={10.1109/NMDC46933.2022.10052561}, abstractNote={In this paper, we first introduced a miniaturized dual excitation laser-coupled intravascular ultrasound transducer with both a piezoelectric stack and a laser ultrasound transducer, which can generate a low-frequency (425 kHz) and high-frequency (7.2 MHz) dual excitation waves for thrombolysis. The prototype transducer can generate peak-negative pressure (PNP) of about 3.0 MPa with 100 Vpp input voltage and 8.5 MPa with 1mJ laser energy input, respectively. The in-vitro thrombolysis showed improved clot mass reduction (61.74 ± 3.15 %) and clot lysis speed (63.12 ± 4.35 mg/min) of dual-excitation ultrasound treatment compared to piezo or laser-generated ultrasound alone treatment.}, journal={2022 IEEE NANOTECHNOLOGY MATERIALS AND DEVICES CONFERENCE, NMDC}, author={Zhang, Bohua and Wu, Huaiyu and Jiang, Xiaoning}, year={2022}, pages={37–40} }
 @misc{yamashita_karaki_lee_wan_kim_jiang_2022, title={A Review of Lead Perovskite Piezoelectric Single Crystals and Their Medical Transducers Application}, volume={69}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2022.3160526}, abstractNote={Piezoelectric materials have been developed since early 1900s and many research had been conducted on the composition and process to obtain higher piezoelectric constants (<inline-formula> <tex-math notation="LaTeX">${d}_{33}$ </tex-math></inline-formula>). Within composition research, lead perovskite relaxor piezoelectric single crystals (SCs) of Pb(Mg1/3Nb2/3)O3–lead titanate PbTiO3 type have been actively studied since 1990s because of their outstanding <inline-formula> <tex-math notation="LaTeX">${d}_{33} >1500$ </tex-math></inline-formula> pC/N compared with those of the conventional Pb(Zr,Ti)O3 ceramics. A major driving force of these SC research has been promoted by mass production of ultrasound transducers and array probes for medical diagnostic systems since early 2000s. However, higher <inline-formula> <tex-math notation="LaTeX">${d}_{33}$ </tex-math></inline-formula> material and process research for these ultrasound devices are almost saturated. In this review article, we present a brief overview of the history, current situation, and future perspective of piezoelectric SCs. The authors believe that the main research in the next century is high <inline-formula> <tex-math notation="LaTeX">${d}_{33}$ </tex-math></inline-formula> SCs with a high composition uniformity and low-energy SC growth methods, such as solid-state SC growth, low-loss SC transducer manufacturing technique, and improved poling process. This is a big technical challenge for all the scientists; however, the relatively large market of medical ultrasound has been expanded year by year, and we hope that the community is motivated to solve such technical problems in the near future.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Yamashita, Yohachi and Karaki, Tomoaki and Lee, Ho-Yong and Wan, Haotian and Kim, Hwang-Pill and Jiang, Xiaoning}, year={2022}, month={Nov}, pages={3048–3056} }
 @misc{kim_wan_luo_sun_yamashita_karaki_lee_jiang_2022, title={A Review on Alternating Current Poling for Perovskite to Relaxor-PbTio(3) Single Crystals}, volume={69}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2022.3181236}, abstractNote={With the great success on verifying its effectiveness on relaxor-PbTiO3 (PT) single crystals (SCs), alternating current poling (ACP) has been taking a center as a new domain engineering method in the last few years. Compared with the conventional direct current poling (DCP), ACP enables enhanced piezoelectric and dielectric properties. In this article, research progress in ACP and perspectives are introduced. Initially, optimized conditions of ACP for relaxor-PT SCs and unsolved issues on polycrystalline ceramics and spurious modes are reviewed. Second, the ferroelectric domain size dependence of piezoelectricity associated with ACP is discussed. We hypothesize that a tradeoff between domain and domain wall contributions exists for high piezoelectricity, suggesting an optimum 109° domain wall size, which is presumably dependent on compositions, crystallographic symmetries, and domain configurations. Finally, crystals synthesized by a solid-state crystal growth (SSCG) method are briefly introduced due to their unprecedented piezoelectricity obtained by ACP ( ${d}_{33} \sim 5500$ pC/N). We hope that this work helps to grasp the current status of ACP and to guide future tasks to be studied.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Kim, Hwang-Pill and Wan, Haotian and Luo, Chengtao and Sun, Yiqin and Yamashita, Yohachi and Karaki, Tomoaki and Lee, Ho-Yong and Jiang, Xiaoning}, year={2022}, month={Nov}, pages={3037–3047} }
 @article{wu_zhang_xu_huang_jiang_2022, title={A multi-directional transducer array for muscle shear wave anisotropy estimation}, ISSN={["1948-5719"]}, DOI={10.1109/IUS54386.2022.9958882}, abstractNote={Ultrasound elastography based on shear wave imaging has been widely used in clinical applications. However, the elasticity of anisotropic tissues, such as muscle and tendon, cannot be measured accurately using shear wave imaging because the shear wave velocity (SWV) varies with tissue fiber orientations. Recently, some researchers reported that anisotropic properties of muscles can be estimated by rotating the transducer for shear wave imaging. However, this approach may be difficult for clinical practices because of the relatively long data acquisition time and the misalignment errors associated with mechanical rotation of the array. Although fully sampled 2-D array can accomplish rotation electrically, the high cost and complexity of imaging hardware system can be a concern. Thus, in this work, we designed and fabricated a multi-directional transducer array in order to measure SWV for exploring the anisotropic properties of muscles. This novel star-shape transducer includes a middle element to generate acoustic radiation force for creating shear wave in tissue, and another 32 elements was alignment to form 4-element arrays for detecting the shear waves in 8 different directions (360°) without physically rotating the transducer. With a wide −6 dB bandwidth (50.9%) and high sensitivity from the receiving elements, the array showed a great potential in assessment of tissue anisotropy.}, journal={2022 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS)}, author={Wu, Huaiyu and Zhang, Bohua and Xu, Guo-Xuan and Huang, Chih-Chung and Jiang, Xiaoning}, year={2022} }
 @article{kim_bautista_deruiter_goel_jiang_xu_dayton_2022, title={An Analysis of Sonothrombolysis and Cavitation for Retracted and Unretracted Clots Using Microbubbles Versus Low-Boiling-Point Nanodroplets}, volume={69}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2021.3137125}, abstractNote={The thrombolysis potential of low-boiling-point (−2 °C) perfluorocarbon phase-change nanodroplets (NDs) has previously been demonstrated on aged clots, and we hypothesized that this efficacy would extend to retracted clots. We tested this hypothesis by comparing sonothrombolysis of both unretracted and retracted clots using ND-mediated ultrasound (US+ND) and microbubble-mediated ultrasound (US+MB), respectively. Assessment data included clot mass reduction, cavitation detection, and cavitation cloud imaging in vitro. Acoustic parameters included a 7.9-MPa peak negative pressure and 180-cycle bursts with 5-Hz repetition (the corresponding duty cycle and time-averaged intensity of 0.09% and 1.87 W/cm2, respectively) based on prior studies. With these parameters, we observed a significantly reduced efficacy of US+MB in the retracted versus unretracted model (the averaged mass reduction rate from 1.83%/min to 0.54%/min). Unlike US+MB, US+ND exhibited less reduction of efficacy in the retracted model (from 2.15%/min to 1.04%/min on average). The cavitation detection results correlate with the sonothrombolysis efficacy results showing that both stable and inertial cavitation generated in a retracted clot by US+ND is higher than that by US+MB. We observed that ND-mediated cavitation shows a tendency to occur inside a clot, whereas MB-mediated cavitation occurs near the surface of a retracted clot, and this difference is more significant with retracted clots compared to unretracted clots. We conclude that ND-mediated sonothrombolysis outperforms MB-mediated therapy regardless of clot retraction, and this advantage of ND-mediated cavitation is emphasized for retracted clots. The primary mechanisms are hypothesized to be sustained cavitation level and cavitation clouds in the proximity of a retracted clot by US+ND.}, number={2}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Kim, Jinwook and Bautista, Kathlyne Jayne B. and Deruiter, Ryan M. and Goel, Leela and Jiang, Xiaoning and Xu, Zhen and Dayton, Paul A.}, year={2022}, month={Feb}, pages={711–719} }
 @article{truong_chiu_lai_huang_jiang_huang_2022, title={Ca2+ signaling-mediated low-intensity pulsed ultrasound-induced proliferation and activation of motor neuron cells}, volume={124}, ISSN={["1874-9968"]}, DOI={10.1016/j.ultras.2022.106739}, abstractNote={Motor neuron diseases (MND) including amyotrophic lateral sclerosis and Parkinson disease are commonly neurodegenerative, causing a gradual loss of nerve cells and affecting the mechanisms underlying changes in calcium (Ca2+)-regulated dendritic growth. In this study, the NSC-34 cell line, a population of hybridomas generated using mouse spinal cord cells with neuroblastoma, was used to investigate the effect of low-intensity pulsed ultrasound (LIPUS) as part of an MND treatment model. After NSC-34 cells were seeded for 24 h, LIPUS stimulation was performed on the cells at days 1 and 3 using a non-focused transducer at 1.15 MHz for 8 min. NSC-34 cell proliferation and morphological changes were observed at various LIPUS intensities and different combinations of Ca2+ channel blockers. The nuclear translocation of Ca2+-dependent transcription factors was also examined. We observed that the neurite outgrowth and cell number of NSC-34 significantly increased with LIPUS stimulation at days 2 and 4, which may be associated with the treatment's positive effect on the activation of Ca2+-dependent transcription factors, such as nuclear factor of activated T cells and nuclear factor-kappa B. Our findings suggest that the LIPUS-induced Ca2+ signaling and transcription factor activation facilitate the morphological maturation and proliferation of NSC-34 cells, presenting a promising noninvasive method to improve stimulation therapy for MNDs in the future.}, journal={ULTRASONICS}, author={Truong, Thi-Thuyet and Chiu, Wen-Tai and Lai, Yi-Shyun and Huang, Hsien and Jiang, Xiaoning and Huang, Chih-Chung}, year={2022}, month={Aug} }
 @article{tang_wu_klippel_zhang_huang_jing_jiang_yao_2022, title={Deep thrombosis characterization using photoacoustic imaging with intravascular light delivery}, volume={12}, ISSN={["2093-985X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85124813833&partnerID=MN8TOARS}, DOI={10.1007/s13534-022-00216-0}, abstractNote={Venous thromboembolism (VTE) is a condition in which blood clots form within the deep veins of the leg or pelvis to cause deep vein thrombosis. The optimal treatment of VTE is determined by thrombus properties such as the age, size, and chemical composition of the blood clots. The thrombus properties can be readily evaluated by using photoacoustic computed tomography (PACT), a hybrid imaging modality that combines the rich contrast of optical imaging and deep penetration of ultrasound imaging. With inherent sensitivity to endogenous chromophores such as hemoglobin, multispectral PACT can provide composition information and oxygenation level in the clots. However, conventional PACT of clots relies on external light illumination, which provides limited penetration depth due to strong optical scattering of intervening tissue. In our study, this depth limitation is overcome by using intravascular light delivery with a thin optical fiber. To demonstrate in vitro blood clot characterization, clots with different acuteness and oxygenation levels were placed underneath ten-centimeter-thick chicken breast tissue and imaged using multiple wavelengths. Acoustic frequency analysis was performed on the received PA channel signals, and oxygenation level was estimated using multispectral linear spectral unmixing. The results show that, with intravascular light delivery, clot oxygenation level can be accurately measured, and the clot age can thus be estimated. In addition, we found that retracted and unretracted clots had different acoustic frequency spectrum. While unretracted clots had stronger high frequency components, retracted clots had much higher low frequency components due to densely packed red blood cells. The PACT characterization of the clots was consistent with the histology results and mechanical tests.}, number={2}, journal={BIOMEDICAL ENGINEERING LETTERS}, author={Tang, Yuqi and Wu, Huaiyu and Klippel, Paul and Zhang, Bohua and Huang, Hsiao-Ying Shadow and Jing, Yun and Jiang, Xiaoning and Yao, Junjie}, year={2022}, month={Feb} }
 @article{xue_zhang_moon_xu_huang_sharma_jiang_2022, title={Development of a wearable ultrasound transducer for sensing muscle activities in assistive robotics applications: In vivo study}, ISSN={["1948-5719"]}, DOI={10.1109/IUS54386.2022.9958535}, abstractNote={People who suffer from the amputation of limbs or with mobility impairment due to methodological disorder sometimes require assistive robotics (AR), such as robotic prostheses and exoskeletons, to function satisfactorily and productively in daily life. Dynamic measurements of muscle voluntary activities are widely used to control AR, and sensors used to control AR should be non-invasive, effective, and wearable. Ultrasound (US) imaging is an effective method for measuring muscle activity. Nevertheless, conventional US transducers are cumbersome and inflexible, making them inconvenient for continuous monitoring of muscle activity for AR control. In light of no report available about using a flexible transducer for detecting muscle activities for AR, this work aims to develop a novel wearable US device for detecting muscle activities. In specific, a 16-element 10 MHz flexible sparse array was designed, fabricated, and characterized. The feasibility of monitoring muscle activity in different regions was demonstrated by an in vivo human experiment.}, journal={2022 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS)}, author={Xue, Xiangming and Zhang, Bohua and Moon, Sunho and Xu, Guo-Xuan and Huang, Chih-Chung and Sharma, Nitin and Jiang, Xiaoning}, year={2022} }
 @article{sun_ota_fujii_yamashita_kim_wan_jiang_karaki_2022, title={Enhanced Properties of 3-MHz Sliver-Mode Vibrators for Cardiac Probes With Alternating Current Poling for Pb(Mg1/3Nb2/3)O-3-PbTiO3 Single Crystals}, volume={69}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2022.3199741}, abstractNote={We investigated the effects of alternating current poling (ACP) on the piezoelectric and dielectric properties of 3-MHz sliver mode (L13 mm <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> W0.10–0.25 mm <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> T0.48 mm) vibrators fashioned from Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PMN-0.30PT) single crystal (SC) plate manufactured using the continuous-feeding Bridgman (CF-BM) method for cardiac probes. The ACP SC plate (L13 mm <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> W24 mm <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> T0.48 mm) exhibited ultrahigh dielectric permittivity (<inline-formula> <tex-math notation="LaTeX">$\varepsilon ^{T}_{33}/\varepsilon _{0}$ </tex-math></inline-formula>) and piezoelectric coefficient (<inline-formula> <tex-math notation="LaTeX">${d}_{33}$ </tex-math></inline-formula>) of 9690 and 2920 pC/N, respectively. After array dicing, the SC slivers with widths of 0.10, 0.15, 0.20, and 0.25 mm were obtained, and their average <inline-formula> <tex-math notation="LaTeX">$\varepsilon ^{T}_{33}/\varepsilon _{0}$ </tex-math></inline-formula> values decreased from the SC plate <inline-formula> <tex-math notation="LaTeX">$\varepsilon ^{T}_{33}/\varepsilon _{0}$ </tex-math></inline-formula> by 45% (5330), 29% (6880), 19% (7840), and 15% (8240), respectively, possibly because of heat and mechanical damage during the dicing. A combination of the ACP and a postdicing direct current poling (ACP-DCP) recovered their <inline-formula> <tex-math notation="LaTeX">$\varepsilon ^{T}_{33}/\varepsilon _{0}$ </tex-math></inline-formula> values to 6050, 7080, 8140, and 8540, respectively. The sliver mode electromechanical coupling factors (<inline-formula> <tex-math notation="LaTeX">${k}'_{33}$ </tex-math></inline-formula>) were confirmed to exceed 93% after the ACP-DCP process, which were more than 4% higher than those of DCP-DCP SC slivers. The measured impedance spectra indicated that the SC slivers with 0.10–0.20 mm in width showed no spurious mode vibration near the fundamental <inline-formula> <tex-math notation="LaTeX">${k}'_{33}$ </tex-math></inline-formula> mode. We conclude that the ACP-DCP SC slivers maintained more enhanced piezoelectric and dielectric properties than the DCP-DCP samples. These results will have important implications for the commercial application of ACP technology to medical imaging ultrasound probes.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Sun, Yiqin and Ota, Yuhei and Fujii, Tadashi and Yamashita, Yohachi and Kim, Hwang-Pill and Wan, Haotian and Jiang, Xiaoning and Karaki, Tomoaki}, year={2022}, month={Nov}, pages={3087–3094} }
 @article{sun_ota_kim_fujii_yamashita_karaki_jiang_wang_2022, title={Enhanced piezoelectric and dielectric properties of AC poled sliver-mode Pb(In1/2Nb1/2)O-3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals for ultrasonic abdomen probes}, volume={61}, ISSN={["1347-4065"]}, DOI={10.35848/1347-4065/ac8142}, abstractNote={Abstract}, number={SN}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS}, author={Sun, Yiqin and Ota, Yuhei and Kim, Hwang-Pill and Fujii, Tadashi and Yamashita, Yohachi and Karaki, Tomoaki and Jiang, Xiaoning and Wang, Zhuangkai}, year={2022}, month={Nov} }
 @article{zhang_wu_kim_dayton_xu_jiang_2022, title={Integration of Forward-viewing and Side-viewing Ultrasound Transducers in an Intravascular Sonothrombolysis Catheter}, ISSN={["1948-5719"]}, DOI={10.1109/IUS54386.2022.9958224}, abstractNote={Thrombosis has emerged as one of the primary factors in mortality rates across the world. Conventional thrombolysis treatments for the rapid dissolution or extraction of massive thrombus, including fibrinolytic therapy and surgical thrombectomy, are time-consuming and may induce risks such as bleeding and vessel wall damage. Here we report a novel intravascular sonothrombolysis device with both forward-viewing and side-viewing elements. The developed FSV transducer prototype has a resonance frequency at 520 kHz and peak negative pressure (PNP) at 4.9 MPa (forward-viewing) and 3.2 MPa (side-viewing) under the driving voltage of 80 V pp. The combination of forward and side-viewing (FSV) ultrasound waves is expected to extend the treatment region and improve thrombolysis efficiency compared to a forward or side-viewing alone sonication.}, journal={2022 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS)}, author={Zhang, Bohua and Wu, Huaiyu and Kim, Jinwook and Dayton, Paul and Xu, Zhen and Jiang, Xiaoning}, year={2022} }
 @article{chen_kim_zhang_yang_osada_crosby_lyerly_jiang_2022, title={Intracorporeal Sonoporation-Induced Drug/Gene Delivery Using a Catheter Ultrasound Transducer}, ISSN={["1948-5719"]}, DOI={10.1109/IUS54386.2022.9958222}, abstractNote={Ultrasound (US) has been recently demonstrated promising in cancer immunotherapy. By virtue of microbubble-mediated cavitation, US can induce temporary pores in the cell membrane to enhance drug/gene delivery and this process is termed sonoporation. Currently, the typical US transducer for sonoporation is extracorporeal, lacking the ability to target lesions behind bones and fat efficiently, as well as to inject microbubbles (MBs) and nucleic acids into the US treatment zone simultaneously. These issues can decrease the drug/gene delivery effectiveness and increase the undesired systemic toxicity for cancer immunotherapy. Here we demonstrated an 800 kHz miniaturized US transducer for intracorporeal sonoporation-induced drug/gene delivery. Acoustic simulation using k-Wave toolbox was carried out to explore the 800 kHz US wave propagation in a 384-well cell culture plate. In-vitro sonoporation tests using human embryonic kidney (HEK) 293T cells and green fluorescent protein-luciferase (GFP-LUC) encoded plasmid DNA were conducted with various sonication parameters (i.e., 0.1 – 0.7 MPa peak-negative pressure; 20 – 2000 cycle number). The LUC assay demonstrated a significantly enhanced transfection, indicating the developed catheter transducer is promising for intracorporeal sonoporation-induced drug/gene delivery, such as intratumoral immunotherapy.}, journal={2022 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS)}, author={Chen, Mengyue and Kim, Howuk and Zhang, Bohua and Yang, Waston and Osada, Takuya and Crosby, Erika J. and Lyerly, H. Kim and Jiang, Xiaoning}, year={2022} }
 @article{chen_zhang_kim_sheng_chen_kim_geng_jiang_2022, title={Millisecond-Level Transient Temperature Monitoring Using an Ultra-Fast Response Thermocouple for Ultrasound-Induced Thermal Strain Imaging}, ISSN={["1948-5719"]}, DOI={10.1109/IUS54386.2022.9958761}, abstractNote={Ultrasound-induced thermal strain imaging (US-TSI) is promising for vulnerable atherosclerosis plaque detection. To avoid arterial motion-induced artifacts, it is needed to induce a very fast temperature rise for US-TSI. Such a short time period for a negligible tissue motion is about 1/8th of a human cardiac cycle, which is corresponding to 75 ms – 125 ms. However, the current temperature monitoring techniques, such as infrared (IR) imaging and magnetic resonance (MR) thermometry, are known with difficulty in monitoring such rapid temperature rises inside biological tissue. Herein, this paper aims to use an ultra-fast response thermocouple to observe rapid temperature rise within 50 ms. Laser-induced thermal tests were conducted in air to verify the feasibility of transient temperature monitoring. Ultrasound-induced thermal tests were conducted in biological tissue to study the influence of various sonication parameters. Obvious transient temperature rises within 50 ms can be observed for both laser tests and tissue tests. The results manifest that the proposed method is capable of monitoring transient temperature rise in biological tissue for US- TSI.}, journal={2022 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS)}, author={Chen, Mengyue and Zhang, Bohua and Kim, Howuk and Sheng, Zhiyu and Chen, Qiyang and Kim, Kang and Geng, Xuecang and Jiang, Xiaoning}, year={2022} }
 @article{liu_kim_huang_chang_jiang_ryu_2022, title={Multiscale and multiphysics FEA simulation and materials optimization for laser ultrasound transducers}, volume={31}, ISSN={["2352-4928"]}, url={http://dx.doi.org/10.1016/j.mtcomm.2022.103599}, DOI={10.1016/j.mtcomm.2022.103599}, abstractNote={The relationship between the nanocomposite design and the laser ultrasound transducer (LUT) characteristics was investigated through simulations in multiple scale levels for material behavior, device response, and acoustic wave propagation in media. First, the effects of the nanoparticle size and concentration on the effective properties of composites were quantitatively investigated with the finite element analysis (FEA) method. Second, the effective properties of the nanocomposite were assigned to the layer, which is modeled as a homogeneous material, in the FEA for the LUT simulating the energy conversion from the incident laser to the acoustic wave. Finally, the ultrasound propagation in the water was calculated by a theoretical wave propagation model. The FEA-based prediction was compared with the experimental data in the literature and a theoretical analysis for LUT based on Thermal-Acoustic coupling. As a result, the ultrasound waves on the transducer surface and at a distance in the water could be predicted. Based on the hierarchically integrated prediction procedure, the optimal conditions of the photoacoustic nanocomposites were investigated through the parametric study with the particle size and concentration as variables. The results guide the material designs optimized for different device characteristics, such as high pressure and broad bandwidth.}, journal={MATERIALS TODAY COMMUNICATIONS}, publisher={Elsevier BV}, author={Liu, Sipan and Kim, Howuk and Huang, Wenbin and Chang, Wei-Yi and Jiang, Xiaoning and Ryu, Jong Eun}, year={2022}, month={Jun} }
 @article{chen_peng_wu_huang_kim_traylor_muller_chhatbar_nam_feng_et al._2022, title={Numerical and experimental evaluation of low-intensity transcranial focused ultrasound wave propagation using human skulls for brain neuromodulation}, volume={11}, ISSN={["2473-4209"]}, DOI={10.1002/mp.16090}, abstractNote={Abstract}, journal={MEDICAL PHYSICS}, author={Chen, Mengyue and Peng, Chang and Wu, Huaiyu and Huang, Chih-Chung and Kim, Taewon and Traylor, Zachary and Muller, Marie and Chhatbar, Pratik Y. and Nam, Chang S. and Feng, Wuwei and et al.}, year={2022}, month={Nov} }
 @misc{peng_cai_chen_jiang_2022, title={Recent Advances in Tracking Devices for Biomedical Ultrasound Imaging Applications}, volume={13}, ISSN={["2072-666X"]}, DOI={10.3390/mi13111855}, abstractNote={With the rapid advancement of tracking technologies, the applications of tracking systems in ultrasound imaging have expanded across a wide range of fields. In this review article, we discuss the basic tracking principles, system components, performance analyses, as well as the main sources of error for popular tracking technologies that are utilized in ultrasound imaging. In light of the growing demand for object tracking, this article explores both the potential and challenges associated with different tracking technologies applied to various ultrasound imaging applications, including freehand 3D ultrasound imaging, ultrasound image fusion, ultrasound-guided intervention and treatment. Recent development in tracking technology has led to increased accuracy and intuitiveness of ultrasound imaging and navigation with less reliance on operator skills, thereby benefiting the medical diagnosis and treatment. Although commercially available tracking systems are capable of achieving sub-millimeter resolution for positional tracking and sub-degree resolution for orientational tracking, such systems are subject to a number of disadvantages, including high costs and time-consuming calibration procedures. While some emerging tracking technologies are still in the research stage, their potentials have been demonstrated in terms of the compactness, light weight, and easy integration with existing standard or portable ultrasound machines.}, number={11}, journal={MICROMACHINES}, author={Peng, Chang and Cai, Qianqian and Chen, Mengyue and Jiang, Xiaoning}, year={2022}, month={Nov} }
 @article{kim_wan_lu_yamashita_jiang_2022, title={Scaling effects in the alternating-current poling of thin PIN-PMN-PT single crystals}, volume={120}, ISSN={["1077-3118"]}, DOI={10.1063/5.0084994}, abstractNote={AC-poling of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals with a thickness of 0.06–0.16 mm was studied in this paper. Compared with DC-poled samples, enhancements in piezoelectric and dielectric properties can be obtained when the thickness is above 0.1 mm. However, inconsistency in poling effects was found in the crystals with thickness below 0.1 mm. To elucidate why such scaling effect arises, surface roughness was measured by an atomic force microscopy to correlate surface morphology and poling effects. It was found that non-uniform surface roughness led to inconsistent and decreased properties. Furthermore, temperature-dependent dielectric permittivity spectra were measured to explore how crystal thickness affects the thermal stability of ferroelectric phases. It is noted that complex changes in crystallographic symmetries emanate by decreasing thickness. Such phenomena can be attributed to more influential effects of surface morphology when thickness is reduced. We hope this work suggests a clue for solving the scaling effects of AC-poling on relaxor-PbTiO3 single crystals.}, number={14}, journal={APPLIED PHYSICS LETTERS}, author={Kim, Hwang-Pill and Wan, Haotian and Lu, Xuanming and Yamashita, Yohachi and Jiang, Xiaoning}, year={2022}, month={Apr} }
 @article{cloutier_levassort_jiang_zhou_2022, title={The Ever-Growing Field of High-Frequency Biomedical Ultrasound}, volume={69}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2022.3174370}, abstractNote={Compared with other medical imaging counterparts, ultrasound has advantages owing to its real-time imaging capability, easy access, and cost-effectiveness. High-frequency (>20 MHz) ultrasound has been developed over the last few decades and is attractive because it provides high-resolution medical imaging and ultrasound backscattering microscopy (UBM) measurements, with applications targeting small animal imaging and some areas of human diagnosis. In recent years, driven by growing needs in intravascular ultrasound (IVUS) imaging, minimally invasive surgery, and particle manipulation, high-frequency ultrasound has continued to flourish as a niche modality and has expanded its important role in both diagnostic imaging and therapy. Concomitant needs have thus arisen in technological research and development to innovate materials, devices, algorithms, and systems for a variety of high-frequency ultrasound applications in medicine and biology.}, number={6}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Cloutier, Guy and Levassort, Franck and Jiang, Xiaoning and Zhou, Qifa}, year={2022}, month={Jun}, pages={1845–1847} }
 @article{zhang_wu_jiang_2022, title={Ultrasound and magnetic dual-mode stacked transducer for sonothrombolysis with a combination of nanodroplets and magnetic nanoparticles}, ISSN={["1944-9380"]}, DOI={10.1109/NANO54668.2022.9928649}, abstractNote={It has been observed that ultrasound thrombolysis is more effective and safer than conventional techniques of thrombolysis, such as mechanical thrombectomy or pharmaceutical medication therapies. Recent work also reported that the dual-mode excitation combining magnetic field and ultrasound helped dramatically increase the thrombolysis rate. Therefore, in this work, based on the dual-mode concept, we demonstrated a 4-element stacked transducer with a center frequency of 450 kHz, which can create ultrasonic waves in addition to a high frequency oscillating magnetic field to activate the superparamagnetic iron oxide nanoparticles (SPIONs) and nanodroplets. Under 250 Vpp input voltage, the transducer reached a peak-negative pressure of 3 MPa. The transducer can simultaneously generate ultrasound cavitation and magnetic pulse excitation, thus providing higher thrombolysis efficiency.}, journal={2022 IEEE 22ND INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY (NANO)}, author={Zhang, Bohua and Wu, Huaiyu and Jiang, Xiaoning}, year={2022}, pages={71–74} }
 @article{wu_zhang_huang_peng_zhou_jiang_2022, title={Ultrasound-Guided Intravascular Sonothrombolysis With a Dual Mode Ultrasound Catheter: In Vitro Study}, volume={69}, ISSN={["1525-8955"]}, url={https://doi.org/10.1109/TUFFC.2022.3153929}, DOI={10.1109/TUFFC.2022.3153929}, abstractNote={Thromboembolism in vessels often leads to stroke or heart attack and even sudden death unless brought under control. Sonothrombolysis based on ultrasound contrast agents has shown promising outcome in effective treatment of thromboembolism. Intravascular sonothrombolysis transducer was reported recently for unprecedented sonothrombolysis <italic>in vitro</italic>. However, it is necessary to provide an imaging guide during thrombolysis in clinical applications for optimal treatment efficiency. In this article, a dual mode ultrasound catheter was developed by combining a 16-MHz high-frequency element (imaging transducer) and a 220-kHz low-frequency element (treatment transducer) for sonothrombolysis <italic>in vitro</italic>. The treatment transducer was designed with a 20-layer PZT-5A stack with the aperture size of <inline-formula> <tex-math notation="LaTeX">$1.2\times1.2$ </tex-math></inline-formula> mm<sup>2</sup>, and the imaging transducer with the aperture size of <inline-formula> <tex-math notation="LaTeX">$1.2\times1.2$ </tex-math></inline-formula> mm<sup>2</sup> was attached in front of the treatment transducer. Both transducers were assembled into a customized 2-lm 10-Fr catheter. <italic>In vitro</italic> experiment was carried out using a bovine blood clot. Imaging tests were conducted, showing that the backscattering signals can be obtained with a high signal-to-noise ratio (SNR) for the 16-MHz imaging transducer. Sonothrombolysis was performed successfully that the volume of clot was reduced significantly after the 30-min treatment. The size changes of clot were observed clearly using the 16-MHz M-mode imaging during the thrombolysis. The findings suggest that the proposed ultrasound-guided intravascular sonothrombolysis can be enhanced since the position of treatment transducer can be adjusted with the target at the clot due to the imaging guide.}, number={6}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Wu, Huaiyu and Zhang, Bohua and Huang, Chih-Chung and Peng, Chang and Zhou, Qifa and Jiang, Xiaoning}, year={2022}, month={Jun}, pages={1917–1925} }
 @article{xu_chen_jiang_huang_2022, title={Visualization of Human Skeletal Muscle Mechanical Anisotropy by Using Dual-Direction Shear Wave Imaging}, volume={69}, ISSN={["1558-2531"]}, DOI={10.1109/TBME.2022.3152896}, abstractNote={Objective: Ultrasound (US) shear wave elasticity imaging (SWEI) is a mature technique for diagnosing the elasticity of isotropic tissues. However, the elasticity of anisotropic tissues, such as muscle and tendon, cannot be diagnosed correctly using SWEI because the shear wave velocity (SWV) varies with tissue fiber orientations. Recently, SWEI has been studied for measuring the anisotropic properties of muscles by rotating the transducer; however, this is difficult for clinical practice. Methods: In this study, a novel dual-direction shear wave imaging (DDSWI) technique was proposed for visualizing the mechanical anisotropy of muscles without rotation. Longitudinal and transverse shear waves were created by a specially designed external vibrator and supersonic pushing beam, respectively; the SWVs were then tracked using ultrafast US imaging. Subsequently, the SWV maps of two directions were obtained at the same scanning cross section, and the mechanical anisotropy was represented as the ratio between them at each pixel. Results: The performance of DDSWI was verified using a standard phantom, and human experiments were performed on the gastrocnemius and biceps brachii. Experimental results of phantom revealed DDSWI exhibited a high precision of <0.81% and a low bias of <3.88% in SWV measurements. The distribution of anisotropic properties in muscle was visualized with the anisotropic ratios of 1.54 and 2.27 for the gastrocnemius and biceps brachii, respectively. Conclusion: The results highlight the potential of this novel anisotropic imaging in clinical applications because the conditions of musculoskeletal fiber orientation can be easily and accurately evaluated in real time by DDSWI.}, number={9}, journal={IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING}, author={Xu, Guo-Xuan and Chen, Pei-Yu and Jiang, Xiaoning and Huang, Chih-Chung}, year={2022}, month={Sep}, pages={2745–2754} }
 @article{wu_hossain_kim_gallippi_jiang_2021, title={A 1.5-D Array for Acoustic Radiation Force (ARF)-Induced Peak Displacement-Based Tissue Anisotropy Assessment With a Row-Column Excitation Method}, volume={68}, ISSN={["1525-8955"]}, url={https://doi.org/10.1109/TUFFC.2020.3030040}, DOI={10.1109/TUFFC.2020.3030040}, abstractNote={Many biological tissues, including muscle or kidney, are mechanically anisotropic, and the degree of anisotropy (DoA) in mechanical properties is diagnostically relevant. DoA can be assessed either using the ratio of shear wave velocities (SWVs) or acoustic radio forced impulse (ARFI)-induced peak displacements (PD) measured longitudinal over transverse orientations. Whether using SWV or PD as a basis, DoA expressed as the ratio of values requires 90° transducer rotation when a linear array is employed. This large rotation angle is prone to misalignment errors. One solution is the use of a fully sampled matrix array for electronic rotation of point spread function (PSF). However, the challenges of matrix array are its high fabrication cost and complicated fabrication procedures. The cheaper and simpler alternative of matrix array is the use of a row–column array. A <inline-formula> <tex-math notation="LaTeX">$3\times64$ </tex-math></inline-formula> elements 1.5-D array with a row–column excitation mode is proposed to assess DoA in mechanical properties using the PD ratio. Different numbers of elements in elevational and lateral directions were selected to have orthogonal ARFI excitation beams without rotating the transducer. A custom-designed flex circuit was used to fabricate the array with a simpler electrode connection than a fully sampled matrix array. The performance of the array was evaluated in Field II simulation and experiment. The output pressure was 0.57-MPa output under a 40-<inline-formula> <tex-math notation="LaTeX">${V}_{\text {pp}}$ </tex-math></inline-formula> excitation with a −6-dB point spread dimension of <inline-formula> <tex-math notation="LaTeX">$14\times4$ </tex-math></inline-formula> mm<sup>2</sup> in orthogonal directions. The PD was measured to be <inline-formula> <tex-math notation="LaTeX">$1.4~\mu \text{m}$ </tex-math></inline-formula> in an isotropic elastic phantom with Young’s modulus of 5.4 kPa. These results suggest that the array is capable of assessing DoA using PD ratio without physical rotation of the transducer. The array has the potential to reduce the misalignment errors for DoA assessment.}, number={4}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Wu, Huaiyu and Hossain, Md Murad and Kim, Howuk and Gallippi, Caterina M. and Jiang, Xiaoning}, year={2021}, month={Apr}, pages={1278–1287} }
 @article{kim_kim_wu_zhang_dayton_jiang_2021, title={A multi-pillar piezoelectric stack transducer for nanodroplet mediated intravascular sonothrombolysis}, volume={116}, ISSN={["1874-9968"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85110135734&partnerID=MN8TOARS}, DOI={10.1016/j.ultras.2021.106520}, abstractNote={We aim to develop a nanodroplet (ND)-mediated intravascular ultrasound (US) transducer for deep vein thrombosis treatments. The US device, having an efficient forward directivity of the acoustic beam, is capable of expediting the clot dissolution rate by activating cavitation of NDs injected onto a thrombus. We designed and prototyped a multi-pillar piezoelectric stack (MPPS) transducer composed of four piezoelectric stacks. Each stack was made of five layers of PZT-4 plates, having a dimension of 0.85 × 0.85 × 0.2 mm3. The transducer was characterized by measuring the electrical impedance and acoustic pressure, compared to simulation results. Next, in-vitro tests were conducted in a blood flow mimicking system using the transducer equipped with an ND injecting tube. The miniaturized transducer, having an aperture size of 2.8 mm, provided a high mechanical index of 1.52 and a relatively wide focal zone of 3.4 mm at 80 Vpp, 0.96 MHz electric input. The mass-reduction rate of the proposed method (NDs + US) was assessed to be 4.1 and 4.6 mg/min with and without the flow model, respectively. The rate was higher than that (1.3-2.7 mg/min) of other intravascular ultrasound modalities using micron-sized bubble agents. The ND-mediated intravascular sonothrombolysis using MPPS transducers was demonstrated with an unprecedented lysis rate, which may offer a new clinical option for DVT treatments. The MPPS transducer generated a high acoustic pressure (~3.1 MPa) at a distance of approximately 2.2 wavelengths from the small aperture, providing synergistic efficacy with nanodroplets for thrombolysis without thrombolytic agents.}, journal={ULTRASONICS}, author={Kim, Howuk and Kim, Jinwook and Wu, Huaiyu and Zhang, Bohua and Dayton, Paul A. and Jiang, Xiaoning}, year={2021}, month={Sep} }
 @article{liu_wang_jiang_2021, title={A phase-field simulation-based approach to determine flexoelectric coefficients from hysteresis loop of ferroelectrics}, volume={130}, ISSN={["1089-7550"]}, DOI={10.1063/5.0055511}, abstractNote={The flexoelectric effects in ferroelectric materials have attracted abundant attention in recent years due to the potential application in microscale mechanical-electrical devices. However, quantifying flexoelectric coefficients in ferroelectrics is still a challenge because of the complex electromechanical coupling in ferroelectric materials. Inspired by the flexoelectric effect-induced skew of the hysteresis curve, an indirect method is proposed in this article to determine the flexoelectric coefficient with reasonably high accuracy. Phase-field simulations show that such skew is stimulated only by the flexoelectric effect, which excludes the influence of other electromechanical coupling effects. In addition, the magnitude of such skew is in linear proportion to the flexoelectric coefficient. The four-point bending PbTiO3 beam model is calculated as an example to obtain the transversal flexoelectric coefficient of f1122.}, number={14}, journal={JOURNAL OF APPLIED PHYSICS}, author={Liu, Chang and Wang, Jie and Jiang, Xiaoning}, year={2021}, month={Oct} }
 @misc{peng_chen_spicer_jiang_2021, title={Acoustics at the nanoscale (nanoacoustics): A comprehensive literature review. Part I: Materials, devices and selected applications}, volume={332}, ISSN={["1873-3069"]}, DOI={10.1016/j.sna.2021.112719}, abstractNote={In the past decade, acoustics at the nanoscale (i.e., nanoacoustics) has evolved rapidly with continuous and substantial expansion of capabilities and refinement of techniques. Motivated by research innovations in the last decade, for the first time, recent advancements of acoustics-associated nanomaterials/nanostructures and nanodevices for different applications are outlined in this comprehensive review, which is written in two parts. As part I of this two-part review, firstly, active and passive nanomaterials and nanostructures for acoustics are presented. Following that, representative applications of nanoacoustics including material property characterization, nanomaterial/nanostructure manipulation, and sensing, are discussed in detail. Finally, a summary is presented with point of views on the current challenges and potential solutions in this burgeoning field.}, journal={SENSORS AND ACTUATORS A-PHYSICAL}, author={Peng, Chang and Chen, Mengyue and Spicer, James B. and Jiang, Xiaoning}, year={2021}, month={Dec} }
 @misc{peng_chen_spicer_jiang_2021, title={Acoustics at the nanoscale (nanoacoustics): A comprehensive literature review. Part II: Nanoacoustics for biomedical imaging and therapy}, volume={332}, ISSN={["1873-3069"]}, DOI={10.1016/j.sna.2021.112925}, abstractNote={In the past decade, acoustics at the nanoscale (i.e., nanoacoustics) has evolved rapidly with continuous and substantial expansion of capabilities and refinement of techniques. Motivated by research innovations in the last decade, for the first time, recent advancements of acoustics-associated nanomaterials/nanostructures and nanodevices for different applications are outlined in this comprehensive review, which is written in two parts. As part II of this two-part review, this paper concentrates on nanoacoustics in biomedical imaging and therapy applications, including molecular ultrasound imaging, photoacoustic imaging, ultrasound-mediated drug delivery and therapy, and photoacoustic drug delivery and therapy. Firstly, the recent developments of nanosized ultrasound and photoacoustic contrast agents as well as their various imaging applications are examined. Secondly, different types of nanomaterials/nanostructures as nanocarriers for ultrasound and photoacoustic therapies are discussed. Finally, a discussion of challenges and future research directions are provided for nanoacoustics in medical imaging and therapy.}, journal={SENSORS AND ACTUATORS A-PHYSICAL}, author={Peng, Chang and Chen, Mengyue and Spicer, James B. and Jiang, Xiaoning}, year={2021}, month={Dec} }
 @article{kim_kerrigan_bourham_jiang_2021, title={AlN Single Crystal Accelerometer for Nuclear Power Plants}, volume={68}, ISSN={["1557-9948"]}, url={https://doi.org/10.1109/TIE.2020.2992002}, DOI={10.1109/TIE.2020.2992002}, abstractNote={Reliable vibration sensing is essential to the immediate detection of unusual vibrations, ensuring the safety of nuclear power plant structures. For nuclear power plant applications, the sensor element must endure the harsh environment while retaining reliable performance. Aluminum nitride (AlN) single crystal is considered a promising candidate for the sensing unit due to its robustness to high temperature (HT) and irradiation conditions. However, there are few efforts in developing industrial accelerometers using AlN bulk-machined materials. This article aims to develop a shear-type accelerometer with AlN single crystal plates. The accelerometer's design is based on the numerical simulation results, followed by the fabrication of the sensor and the extensive validation under HT (∼1000 °C). The sensitivity of the accelerometer was about 9.2 pC/g. The prototype sensor showed stable performance at varying temperatures from room temperature to 1000 °C. Furthermore, the sensitivity of the accelerometer was successfully sustained for 10 h under HT exposure of 1000 °C, and no obvious mechanical damage was detected after the test. After gamma irradiation for 1 month, the sensor performed stably, without any significant change in sensitivity. The developed AlN accelerometer can be a promising option to monitor the structural integrity of nuclear power plant structures.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Kim, Howuk and Kerrigan, Sean and Bourham, Mohamed and Jiang, Xiaoning}, year={2021}, month={Jun}, pages={5346–5354} }
 @article{wan_luo_liu_chang_yamashita_jiang_2021, title={Alternating current poling on sliver-mode rhombohedral Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals}, volume={208}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2021.116759}, abstractNote={Sliver-mode 0.73Pb(Mg1/3Nb2/3)O3-0.27PbTiO3 single crystals were poled by the alternating current electric field (ACP) along the [001] direction for low-frequency transducer applications. Under ACP with optimized conditions (2.89 kVrms, 0.1 Hz, 10 cycles), the free dielectric constant (εT33/ε0) was enhanced from 5300 to 7220 and piezoelectric coefficient (d33) was improved from 1410 to 1920 pC/N, both are about 36% higher than those under traditional direct current poling. The piezoresponse force microscopy observation and phase-field simulation show the similar domain morphologies evolution. During the ACP process, the domain morphology first changes from ‘4R’ to ‘2R’ configuration, and then the length of the 109° domain wall keeps increasing, which leads to a longer range of ordering and a stable lamellar domain structure in the end. The correlation between the domain morphology and the coercive field is also found in both the experiment and simulation. These findings on the effect and mechanism of ACP will help develop advanced low-frequency single crystal transducer arrays.}, journal={ACTA MATERIALIA}, author={Wan, Haotian and Luo, Chengtao and Liu, Chang and Chang, Wei-Yi and Yamashita, Yohachi and Jiang, Xiaoning}, year={2021}, month={Apr} }
 @article{prieto_shah_rosenbaum_jiang_musonda_price_stringer_vwalika_stamilio_stringer_2021, title={An automated framework for image classification and segmentation of fetal ultrasound images for gestational age estimation}, volume={11596}, ISSN={["1996-756X"]}, DOI={10.1117/12.2582243}, abstractNote={Accurate assessment of fetal gestational age (GA) is critical to the clinical management of pregnancy. Industrialized countries rely upon obstetric ultrasound (US) to make this estimate. In low- and middle- income countries, automatic measurement of fetal structures using a low-cost obstetric US may assist in establishing GA without the need for skilled sonographers. We present a technique for generating raw images suitable for model training by removing caliper and text annotation and describe a fully automated pipeline for image classification, segmentation, and structure measurement to estimate the GA. he resulting framework achieves an average accuracy of 93% in classification tasks, a mean Intersection over Union accuracy of 0.91 during segmentation tasks, and a mean measurement error of 1.89 centimeters, finally leading to a 1.4 day mean average error in the predicted GA compared to expert sonographer GA estimate using the Hadlock equation.}, journal={MEDICAL IMAGING 2021: IMAGE PROCESSING}, author={Prieto, Juan C. and Shah, Hina and Rosenbaum, Alan J. and Jiang, Xiaoning and Musonda, Patrick and Price, Joan T. and Stringer, Elizabeth M. and Vwalika, Bellington and Stamilio, David M. and Stringer, Jeffrey S. A.}, year={2021} }
 @article{chen_peng_kim_chhatbar_muller_feng_jiang_2021, title={Biosafety of Low-Intensity Pulsed Transcranial Focused Ultrasound Brain Stimulation - A Human Skull Study}, volume={11593}, ISSN={["1996-756X"]}, DOI={10.1117/12.2582487}, abstractNote={Among a variety of existing modalities for noninvasive brain stimulation (NIBS), low-intensity pulsed transcranial focused ultrasound (tFUS) is a promising technique to precisely stimulate deep brain structures due to its high spatial specificity and superior penetration depth. While tFUS is gaining momentum as an emerging NIBS technique, an advisable biosafety-associated combination of sonication parameters including duty cycle and power input remains to be explored. In this study, biosafety of low-intensity pulsed tFUS using various sonication parameters was evaluated by measuring acoustic intensities and temperature variations across a piece of real human skull. The results showed that ISPTA above 480 mW/cm^2 is likely to induce an excessive temperature rise for a sonication duration of 160 seconds. Also, the skull base effect and ultrasound transducer self-heating effect should be noted during the sonication. Based on the findings in this study, an initial biosafety guide was discussed for the future investigation of ultrasound-mediated NIBS.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS XV}, author={Chen, Mengyue and Peng, Chang and Kim, Taewon and Chhatbar, Pratik Y. and Muller, Marie and Feng, Wuwei and Jiang, Xiaoning}, year={2021} }
 @article{peng_chen_wang_shen_jiang_2021, title={Broadband Piezoelectric Transducers for Under-Display Ultrasonic Fingerprint Sensing Applications}, volume={68}, ISSN={["1557-9948"]}, DOI={10.1109/TIE.2020.2984977}, abstractNote={Smartphones today have attracted a continuous trend of pursuing narrow-bezel and full-screen displays. To allow for a more user-friendly front side fingerprint recognition in full-screen displays, it is crucial to develop an under-display type of fingerprint sensor. Among fingerprint sensing techniques, ultrasonic fingerprint sensing has been proved to be able to provide more distinctive features and give a high resistance to spoof attacks. However, until now no study about under-display ultrasonic fingerprint sensing has been reported. In this article, for the first time, multilayer under-display ultrasonic fingerprint sensor structure using various active materials/structures were theoretically designed and compared. Based on the theoretical analysis results, a lead zirconate titanate (PZT)-5A-based multilayer under-display ultrasonic fingerprint sensor with a resonant frequency of 20 MHz, and a −6-dB fractional bandwidth of more than 70% was fabricated to meet the requirements of resolution and sensitivity for the under-display ultrasonic fingerprint imaging applications. The prototyped sensor was characterized, and the fingerprint recognition capability was tested using a custom-made fingerprint-mimicking phantom. The phantom images were acquired based on the pulse-echo imaging method. With the 1 μJ impulse driving signal, the sensor was manipulated to image a 2.0 mm × 1.0 mm section of fingerprint-mimicking phantom by mechanical scanning, obtaining an electronic image with 500 × 500 DPI. The fingerprint-mimicking phantom imaging results suggest that the 20 MHz broadband PZT-based multilayer structure holds great potential for under-display ultrasonic fingerprint sensor applications.}, number={5}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Peng, Chang and Chen, Mengyue and Wang, Hongchao and Shen, Jian and Jiang, Xiaoning}, year={2021}, month={May}, pages={4426–4434} }
 @article{chen_sheng_kim_zhang_chen_kim_geng_jiang_2021, title={Design and Simulation of Heating Transducer Arrays for Ultrasound-Induced Thermal Strain Imaging}, ISSN={["1948-5719"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85122893882&partnerID=MN8TOARS}, DOI={10.1109/IUS52206.2021.9593531}, abstractNote={Ultrasound-induced thermal strain imaging (US-TSI) has been proposed as an effective diagnostic modality for atherosclerosis plaque detection. The main challenge of current US-TSI for human subjects is the demand for a very fast temperature rise in a relatively large volume, with appropriate acoustic power that is under the Food and Drug Administration (FDA) safety limit, to cover a major artery such as carotid, and to avoid any physiologic motion artifacts. Therefore, we aim to develop heating transducer arrays with satisfied capabilities in terms of heating volume and speed for US-TSI. By virtue of using symmetrical 3.5 MHz dual 1.5D arrays and applying the dual-focus beamforming approach, the acoustic and thermal simulation results demonstrated that the designed dual heating arrays can induce a 2.1 °C temperature rise within 50 ms in a volume of 2 × 10 × 10 mm3(in terms of full width at half maximum, FWHM). The transmitting sensitivity and power conversion efficiency for a single element was estimated to be 14.1 kPa/V and 72.43%, respectively. It showed that the designed dual 1.5D heating transducer arrays can be promising for US-TSI applications.}, journal={INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS 2021)}, author={Chen, Mengyue and Sheng, Zhiyu and Kim, Howuk and Zhang, Bohua and Chen, Qiyang and Kim, Kang and Geng, Xuecang and Jiang, Xiaoning}, year={2021} }
 @misc{nam_traylor_chen_jiang_feng_chhatbar_2021, title={Direct Communication Between Brains: A Systematic PRISMA Review of Brain-To-Brain Interface}, volume={15}, ISSN={["1662-5218"]}, url={http://dx.doi.org/10.3389/fnbot.2021.656943}, DOI={10.3389/fnbot.2021.656943}, abstractNote={This paper aims to review the current state of brain-to-brain interface (B2BI) technology and its potential. B2BIs function via a brain-computer interface (BCI) to read a sender's brain activity and a computer-brain interface (CBI) to write a pattern to a receiving brain, transmitting information. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) to systematically review current literature related to B2BI, resulting in 15 relevant publications. Experimental papers primarily used transcranial magnetic stimulation (tMS) for the CBI portion of their B2BI. Most targeted the visual cortex to produce phosphenes. In terms of study design, 73.3% (11) are unidirectional and 86.7% (13) use only a 1:1 collaboration model (subject to subject). Limitations are apparent, as the CBI method varied greatly between studies indicating no agreed upon neurostimulatory method for transmitting information. Furthermore, only 12.4% (2) studies are more complicated than a 1:1 model and few researchers studied direct bidirectional B2BI. These studies show B2BI can offer advances in human communication and collaboration, but more design and experiments are needed to prove potential. B2BIs may allow rehabilitation therapists to pass information mentally, activating a patient's brain to aid in stroke recovery and adding more complex bidirectionality may allow for increased behavioral synchronization between users. The field is very young, but applications of B2BI technology to neuroergonomics and human factors engineering clearly warrant more research.}, journal={FRONTIERS IN NEUROROBOTICS}, publisher={Frontiers Media SA}, author={Nam, Chang S. and Traylor, Zachary and Chen, Mengyue and Jiang, Xiaoning and Feng, Wuwei and Chhatbar, Pratik Yashvant}, year={2021}, month={May} }
 @article{wu_goel_kim_zhang_kim_dayton_xu_jiang_2021, title={Dual-Frequency Intravascular Sonothrombolysis: An In Vitro Study}, volume={68}, ISSN={["1525-8955"]}, url={https://doi.org/10.1109/TUFFC.2021.3103409}, DOI={10.1109/TUFFC.2021.3103409}, abstractNote={Thrombo-occlusive disease is one of the leading causes of death worldwide. There has been active research on safe and effective thrombolysis in preclinical and clinical studies. Recently, the dual-frequency transcutaneous sonothrombolysis with contrast agents [microbubbles (MBs)] has been reported to be more efficient in trigging the acoustic cavitation, which leads to a higher lysis rate. Therefore, there is increasing interest in applying dual-frequency technique for more significant efficacy improvement in intravascular sonothrombolysis since a miniaturized intravascular ultrasound transducer typically has a limited power output to fully harness cavitation effects. In this work, we demonstrated this efficacy enhancement by developing a new broadband intravascular transducer and testing dual-frequency sonothromblysis in vitro. A broadband intravascular transducer with a center frequency of 750 kHz and a footprint size of 1.4 mm was designed, fabricated, and characterized. The measured −6-dB fractional bandwidth is 68.1%, and the peak negative pressure is 1.5 MPa under the driving voltage of 80 Vpp. By keeping one frequency component at 750 kHz, the second frequency component was selected from 450 to 650 kHz with an interval of 50 kHz. The in vitro sonothrombolysis tests were conducted with a flow model and the results indicated that the MB-mediated, dual-frequency (750+500 kHz) sonothrombolysis yields an 85% higher lysis rate compared with the single-frequency treatment, and the lysis rate of dual-frequency sonothrombolysis increases with the difference between the two frequency components. These findings suggest a dual-frequency excitation technique for more efficient intravascular sonothrombolysis than conventional single-frequency excitation}, number={12}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Wu, Huaiyu and Goel, Leela D. and Kim, Howuk and Zhang, Bohua and Kim, Jinwook and Dayton, Paul A. and Xu, Zhen and Jiang, Xiaoning}, year={2021}, month={Dec}, pages={3599–3607} }
 @article{ji_wang_liu_jiang_zhang_peng_sang_sun_wang_2021, title={Dual-liquid-gated electrochemical transistor and its neuromorphic behaviors}, volume={87}, ISSN={["2211-3282"]}, DOI={10.1016/j.nanoen.2021.106116}, abstractNote={Organic electrochemical transistors (OECTs) are attracting great interest in the field of bioelectronics due to their low operating voltage, flexibility, and biocompatibility. Tunability of the static and transient characteristics renders OECTs with flexible electrical responses and versatile functionalities. However, existing tuning methods are known by changing the structure or composition of OECTs, which are empirical due to the lack of accurate structure-function relationships. Here, we report a post-fabrication and facile tuning method by using a dual-liquid-gate configuration. Based on this, critical parameters of OECT, e.g., threshold voltage (VTH), gate bias for the peak transconductance (VG(g*m)), electric hysteresis (Vhys), minimum of the subthreshold swing (SS*), and response time (τ), can be readily tuned over a range of 0.52 V, 0.48 V, 0.20 V, 0.38 V/decade and 7.2 ms, respectively. We have also developed corresponding mathematical analyses based on the dual-liquid-gating process. Detailed studies on the transient electrical properties demonstrate that auxiliary-gate biases influence the electrochemical doping/de-doping state of the semiconducting channel during the main-gate bias sweeping. Furthermore, typical neuromorphic behaviors of paired-pulse depression and decay time were successfully controlled by varying the auxiliary-gate bias. The proposed dual-liquid-gating is ready for precise engineering on OECT, which is beneficial as an effective tool for conducting an in-depth theoretical study on OECT, constructing multifunctional sensors, and developing more plasticizable neuromorphic devices.}, journal={NANO ENERGY}, author={Ji, Jianlong and Wang, Hongwang and Liu, Ran and Jiang, Xiaoning and Zhang, Qiang and Peng, Yubo and Sang, Shengbo and Sun, Qijun and Wang, Zhong Lin}, year={2021}, month={Sep} }
 @article{ji_wang_wang_zhang_duan_sang_huang_li_zhang_jiang_2021, title={Dynamic-coupling analyses of cells localization by the negative dielectrophoresis}, volume={235}, ISSN={["2041-2983"]}, DOI={10.1177/0954406220929050}, abstractNote={Negative dielectrophoresis is widely used in cell localization for long-term observations such as the impedance analysis, in vivo drug screening, and cell patterns. However, the coupling effect of AC electrokinetics, including negative dielectrophoresis, AC electroosmosis, and electrothermal flow is still unclear. This work investigated cell localization based on the dynamic-coupling of dielectrophoresis, AC electroosmosis, and electrothermal flow. A two-dimensional finite element model that consisted of interdigitated array electrodes was established. The effects of system parameters on the capture efficiency were investigated, when the medium conductivity was in the range of 0.001–1 S/m. The selection of the medium conductivity is suggested to be the first step of the experiment design. Then, the choice of AC frequency and AC amplitude requires balancing the effects of transmembrane potential and temperature rise on cell viability. Besides, particular electrode spacing is evidenced to be only efficient for a specific cell diameter. Thus, the electrode spacing of the microfluidic chip needs to be optimized according to the cell's diameter.}, number={2}, journal={PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE}, author={Ji, Jianlong and Wang, Jingxiao and Wang, Liu and Zhang, Qiang and Duan, Qianqian and Sang, Shengbo and Huang, Qing and Li, Shanshan and Zhang, Wendong and Jiang, Xiaoning}, year={2021}, month={Jan}, pages={402–411} }
 @misc{kim_park_chhatbar_feld_mac grory_nam_wang_chen_jiang_feng_2021, title={Effect of Low Intensity Transcranial Ultrasound Stimulation on Neuromodulation in Animals and Humans: An Updated Systematic Review}, volume={15}, ISSN={["1662-453X"]}, DOI={10.3389/fnins.2021.620863}, abstractNote={Background: Although low-intensity transcranial ultrasound stimulation (LI-TUS) has received more recognition for its neuromodulation potential, there remains a crucial knowledge gap regarding the neuromodulatory effects of LI-TUS and its potential for translation as a therapeutic tool in humans.}, journal={FRONTIERS IN NEUROSCIENCE}, author={Kim, Taewon and Park, Christine and Chhatbar, Pratik Y. and Feld, Jody and Mac Grory, Brian and Nam, Chang S. and Wang, Pu and Chen, Mengyue and Jiang, Xiaoning and Feng, Wuwei}, year={2021}, month={Apr} }
 @article{wan_luo_chung_yamashita_jiang_2021, title={Enhanced dielectric and piezoelectric properties of manganese-doped Pb(In1/2Nb1/2)O-3-Pb(Mg1/3Nb2/3)O-3-PbTiO3 single crystals by alternating current poling}, volume={118}, ISSN={["1077-3118"]}, DOI={10.1063/5.0038207}, abstractNote={Alternating current poling (ACP) was performed on Gen III relaxor-PT Mn-doped Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (Mn: PIN-PMN-PT) single crystals with the poling direction of [001]. Experimental results proved that ACP could bring property enhancement to both k31 and k33 mode crystals. Compared to those from traditional direct current poling (DCP), ACP with the optimized conditions (20 kV/cm, 0.1 Hz, and 20 cycles) enhanced the dielectric and piezoelectric properties of k31-mode mode crystals by more than 30%, where the enhanced free dielectric constant and piezoelectric coefficient d33 reached 5300 and 1750 pC/N, respectively. Furthermore, replacing DCP with ACP could increase the advantages of Gen III relaxor-PT. The coupling factors k31 and k33 were enhanced to 0.472 and 0.915, the mechanical quality factor Qm was enhanced by 17%, and the depoling temperature was raised by 17 °C to 123 °C. In the following mechanism study, in situ x-ray diffraction (XRD) combined with the temperature-dependent dielectric constant measurement proved the introduction of the monoclinic phases after ACP, while piezoresponse force microscopy (PFM) observation showed “2R”-like “2M” domain morphologies in ACP single crystals. Both these intrinsic and extrinsic factors are believed to be the keys to the mechanisms of property enhancement behind ACP. This study proved that ACP is an effective property enhancement method suitable for Gen III relaxor-PT single crystals and will promote its applications in high-temperature and high-power devices.}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={Wan, Haotian and Luo, Chengtao and Chung, Ching-Chang and Yamashita, Yohachi and Jiang, Xiaoning}, year={2021}, month={Mar} }
 @article{stocker_shi_ives_maxwell_dayton_jiang_xu_owens_2021, title={IN VIVO PORCINE AGED DEEP VEIN THROMBOSIS MODEL FOR TESTING ULTRASOUND-BASED THROMBOLYSIS TECHNIQUES}, volume={47}, ISSN={["1879-291X"]}, DOI={10.1016/j.ultrasmedbio.2021.08.017}, abstractNote={As blood clots age, many thrombolytic techniques become less effective. To fully evaluate these techniques for potential clinical use, a large animal aged-clot model is needed. Previous minimally invasive attempts to allow clots to age in an in vivo large animal model were unsuccessful because of the clot clearance associated with relatively high level of cardiac health of readily available research pigs. Prior models have thus subsequently used invasive surgical techniques with the associated morbidity, animal stress and cost. We propose a method for forming sub-acute venous blood clots in an in-vivo porcine model. The age of the clots can be controlled and varied. By using an intravenous scaffold to anchor the clot to the vessel wall during the aging process, we can show that sub-acute clots can consistently be formed with a minimally invasive, percutaneous approach. The clot formed in this study remained intact for at least 1 wk in all subjects. Therefore, we established a new minimally invasive, large animal aged-clot model for evaluation of thrombolytic techniques.}, number={12}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Stocker, Greyson E. and Shi, Jiaqi and Ives, Kimberly and Maxwell, Adam D. and Dayton, Paul A. and Jiang, Xiaoning and Xu, Zhen and Owens, Gabe E.}, year={2021}, month={Dec}, pages={3447–3457} }
 @article{wu_kim_zhang_kim_dayton_xu_jiang_2021, title={Intravascular Dual-frequency Ultrasound Transducer Using a Stack Composite}, ISSN={["1948-5719"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85122850530&partnerID=MN8TOARS}, DOI={10.1109/IUS52206.2021.9593424}, abstractNote={Intravascular sonothrombolysis has attracted much attention due to the safe and effective treatment potential compared to other conventional mechanical thrombectomy and high-dose medication. Meanwhile, multiple frequency sonothrombolysis is known to be more efficient to activate cavitation of micro or nano size contrast agents. Yet, the multiple frequency effects combined with an intravascular device have rarely been studied in the past due to technical limitations in transmitting acoustic pressure output with multiple frequencies from a single small aperture. Therefore, in this study, an intravascular ultrasound transducer with a composite structure is reported, which can operate with the dual-frequency condition for enhancing the cavitation effect of infused contrast agents. Compared with single frequency excitation, the in-vitro test results showed a 34% improvement in the lysis rate when the dual-frequency excitation was applied with the nanodroplets infusion.}, journal={INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS 2021)}, author={Wu, Huaiyu and Kim, Howuk and Zhang, Bohua and Kim, Jinwook and Dayton, Paul and Xu, Zhen and Jiang, Xiaoning}, year={2021} }
 @article{zhang_wu_jiang_2021, title={Laser beam guided magnetic scanning catheter for sonothrombolysis with real-time clot detection}, ISSN={["1948-5719"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85122857665&partnerID=MN8TOARS}, DOI={10.1109/IUS52206.2021.9593555}, abstractNote={Thrombosis diseases have become one of the primary causes of death globally. Existing thrombolysis techniques such as using tPA (or tissue plasminogen activators) for successful dissolution of large thrombus often have a slow therapy time and complications including excessive bleeding. Besides, it is challenging to track the real-time clot location without using x-ray fluoroscopy. Here we report a novel magnetically driven scanning catheter device that integrates a stacked transducer, a tiny ring magnet, and fiber-optic laser sensors for clot spot tracking during the thrombolysis process. The magnetic scanning motion of the catheter induced by the rotational magnetic field is expected to extend the treatment region and improve thrombolysis efficiency.}, journal={INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS 2021)}, author={Zhang, Bohua and Wu, Huaiyu and Jiang, Xiaoning}, year={2021} }
 @article{kim_kim_jiang_2021, title={Laser ultrasonic defect localization using an omni-arrayed candle soot nanoparticle patch}, volume={60}, ISSN={["1347-4065"]}, DOI={10.35848/1347-4065/ac2012}, abstractNote={The generation of ultrasonic surface waves with lasers has become a useful noncontact NDT&E tool. This laser ultrasound technique provides a very flexible and simple method for noncontact and remote generation of ultrasonic surface waves, and has the advantage that various wave shapes can be easily produced by changing the shape of the beam that is illuminating the target. In this work, a laser ultrasound NDT&E method is proposed for defect localization by incorporating an omni-arrayed patterned candle soot nanoparticles-polydimethylsiloxane (CSNP-PDMS) patch. The omni-arrayed CSNP-PDMS patch generates a surface wave with a selective range of frequency, and an omni-directional signal with high amplitude, which surpasses the limitation of the line-arrayed patch. Further, the arrival time algorithm was adopted to validate the effectiveness of the omni-directional patch for 2D damage detection, which in turn the maximum magnitude of contour mapping from calculation agrees well with the true defect location.}, number={10}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS}, author={Kim, Taeyang and Kim, Howuk and Jiang, Xiaoning}, year={2021}, month={Oct} }
 @article{kim_kim_garcia_fang_jiang_2021, title={Liquid metallic laser ultrasound transducer for high-temperature applications}, volume={118}, ISSN={["1077-3118"]}, url={https://doi.org/10.1063/5.0046052}, DOI={10.1063/5.0046052}, abstractNote={This study aims to investigate a laser ultrasound (LUS) transducer for high-temperature (>100 °C) applications. For decades, many researchers have investigated efficient LUS transducers, yet studies on laser ultrasound transducers capable of performing at the high-temperature condition are rarely found in the literature. Most current LUS transducers still utilize a polymer-based composite material, that is, not stable at varying temperature conditions. This study introduces a liquid metallic (LM) LUS transducer that utilizes field's metal, which has a high thermal expansion (∼3 × 10−4 K−1). We hypothesized that such a high thermal expansion of the liquid metal can effectively produce laser-generated ultrasound waves, substituting for conventional polymer-based transducers. A numerical simulation predicted that the LM LUS transducer would produce higher LUS intensity (∼22 dB) than that without the LUS transducer. Experiment results confirmed that the LM transducer effectively intensifies the ultrasound wave signals, obtaining a signal-to-noise gain over 30 dB. Moreover, the transducer was found capable of transmitting detectable wave packets in relatively high-temperature conditions (∼400 °C), while conventional candle soot nanoparticle-polydimethylsiloxane could not perform stably at these elevated temperatures. The investigations introduced in this article are scientifically significant since we demonstrated the engineering feasibility of liquid metallic materials for LUS transducers.}, number={18}, journal={APPLIED PHYSICS LETTERS}, author={Kim, Howuk and Kim, Kyunghoon and Garcia, Nicholas and Fang, Tiegang and Jiang, Xiaoning}, year={2021}, month={May} }
 @article{zhang_wu_goel_kim_peng_kim_dayton_gao_jiang_2021, title={Magneto-sonothrombolysis with combination of magnetic microbubbles and nanodroplets}, volume={116}, ISSN={["1874-9968"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85107639068&partnerID=MN8TOARS}, DOI={10.1016/j.ultras.2021.106487}, abstractNote={This paper reports a novel technique using the rotational magnetic field oscillation and low-intensity sub-megahertz ultrasound stimulation of magnetic microbubbles (MMBs) to promote the nanodroplets (NDs) phase transition and improve the permeation of NDs into the blood clot fibrin network to enhance the sonothrombolysis efficiency. In this study, the influence of different treatment methods with a combination of MMBs and NDs on the thrombolysis rate of both unretracted and retracted clots were investigated, including the stable and inertial cavitation, tPA effects, MMBs/NDs concentration ratio, sonication factors (input voltage, duty cycle) and rotational magnetic field factors (flux density, frequency). We demonstrated that tPA-mediated magneto-sonothrombolysis in combining NDs with MMBs could significantly enhance in vitro lysis of both unretracted clots (85 ± 8.3%) and retracted clots (57 ± 6.5%) in a flow model with 30 min treatment. The results showed that the combination of MMBs and NDs substantially improves in vitro lysis of blood clots with an unprecedented lysis rate.}, journal={ULTRASONICS}, author={Zhang, Bohua and Wu, Huaiyu and Goel, Leela and Kim, Howuk and Peng, Chang and Kim, Jinwook and Dayton, Paul A. and Gao, Yu and Jiang, Xiaoning}, year={2021}, month={Sep} }
 @article{zhang_wu_jiang_2021, title={Miniaturized Dual-Mode Intravascular Transducer for Sonothrombolysis}, ISSN={["2378-377X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85125327134&partnerID=MN8TOARS}, DOI={10.1109/NMDC50713.2021.9677491}, abstractNote={Compared with traditional thrombolysis methods such as mechanical thrombectomy or pharmaceutical drug treatment, ultrasound thrombolysis has been reported to have high thrombolysis efficiency and safety. Notably, the intravascular thrombolysis with miniaturized ultrasound devices has drawn more attention due to its drug and agent delivery capability during the sonothrombolysis process. This paper presented a miniaturized dual-mode ultrasound transducer with piezoelectric stacks and a laser ultrasound transducer. By combining a low-frequency (600 kHz) tone burst sonication and a high-frequency (7.4 MHz) laser ultrasound pulse excitation, intravascular sonothrombolysis with enhanced thrombolysis was expected.}, journal={2021 IEEE 16TH NANOTECHNOLOGY MATERIALS AND DEVICES CONFERENCE (NMDC 2021)}, author={Zhang, Bohua and Wu, Huaiyu and Jiang, Xiaoning}, year={2021} }
 @article{goel_wu_zhang_kim_dayton_xu_jiang_2021, title={Nanodroplet-mediated catheter-directed sonothrombolysis of retracted blood clots}, volume={7}, ISSN={["2055-7434"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85098869774&partnerID=MN8TOARS}, DOI={10.1038/s41378-020-00228-9}, abstractNote={Abstract}, number={1}, journal={MICROSYSTEMS & NANOENGINEERING}, author={Goel, Leela and Wu, Huaiyu and Zhang, Bohua and Kim, Jinwook and Dayton, Paul A. and Xu, Zhen and Jiang, Xiaoning}, year={2021}, month={Jan} }
 @article{peng_chen_sim_zhu_jiang_2021, title={Noninvasive and Nonocclusive Blood Pressure Monitoring via a Flexible Piezo-Composite Ultrasonic Sensor}, volume={21}, ISSN={["1558-1748"]}, DOI={10.1109/JSEN.2020.3021923}, abstractNote={Continuous blood pressure monitoring in everyday life is important and necessary to detect and control high blood pressure in advance. While the existing blood pressure monitoring techniques are well suited for applications in current clinical settings, they are inadequate for next-generation wearable long-term monitoring of blood pressure on a daily basis. In this study, a flexible piezo-composite ultrasonic sensor was reported, for the first time, for continuous blood pressure measurement through ultrasonic motion tracking of blood vessel wall. A flexible piezo-composite ultrasonic sensor was designed and fabricated with a layer of PZT-5A/ polydimethylsiloxane (PDMS) anisotropic 1–3 composite and silver nanowire based stretchable electrodes. The material properties and dimensions of the sensor were determined according to the volume fraction of PZT-5A and the material properties of PZT-5A and PDMS. The experimental results illustrated that the flexible sensor possessed adequate bandwidth and sensitivity for blood pressure monitoring. Continuous blood pressure measurement was successfully conducted with the ulnar artery on a volunteer’s right arm. Compared with the measurement results using a clinical ultrasound probe and a commercial upper arm blood monitor, the results obtained in this study demonstrated the capability of the proposed flexible sensor to continuously monitor blood pressure waveforms during cardiac cycles. The flexible sensor provides a promising solution for noninvasive, nonocclusive and calibration-free blood pressure monitoring. It has great potential to be integrated into a wearable ultrasonic healthcare sensing system for blood pressure and flow monitoring.}, number={3}, journal={IEEE SENSORS JOURNAL}, author={Peng, Chang and Chen, Mengyue and Sim, Hun Ki and Zhu, Yong and Jiang, Xiaoning}, year={2021}, month={Feb}, pages={2642–2650} }
 @article{wan_yamashita_jiang_2021, title={Observation of the Domain Morphology of Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) Single Crystals}, ISSN={["2378-377X"]}, DOI={10.1109/NMDC50713.2021.9677513}, abstractNote={Relaxor-PbTiO3 Single crystals including Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT) have been widely used and extensively studied in the last two decades due to their ultrahigh piezoelectric properties for acoustic devices. However, the piezoelectric properties of PMN-xPT single crystals are highly dependent on the PT contents. In this work, the domain morphologies of PMN-xPT with different PT compositions (x = 0.26 and 0.28, rhombohedral phase) after direct current poling (DCP) were observed by piezoresponse force microscopy (PFM). The domain morphologies and the domain wall densities were compared to study the influences of the PT compositions on the piezoelectric properties of PMN-xPT. The PFM images showed that after DCP, PMN-xPT single crystals of two different compositions all had the domain morphologies with ‘4R’ configuration in which both 109° and 71° domain walls could be clearly identified. Compared with PMN-0.26PT, PMN-0.28PT single crystals had similar 109° domain wall densities (Domain width: 1012 nm vs 1025 nm) but higher 71° domain wall densities (Domain width: 426 nm vs 645 nm). The higher piezoelectric properties of PMN-xPT single crystals were found to correlate with the higher 71° domain wall densities.}, journal={2021 IEEE 16TH NANOTECHNOLOGY MATERIALS AND DEVICES CONFERENCE (NMDC 2021)}, author={Wan, Haotian and Yamashita, Yohachi and Jiang, Xiaoning}, year={2021} }
 @article{cai_peng_lu_prieto_rosenbaum_stringer_jiang_2021, title={Performance Enhanced Ultrasound Probe Tracking With a Hemispherical Marker Rigid Body}, volume={68}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2021.3058145}, abstractNote={Among tracking techniques applied in the 3-D freehand ultrasound (US), the camera-based tracking method is relatively mature and reliable. However, constrained by manufactured marker rigid bodies, the US probe is usually limited to operate within a narrow rotational range before occlusion issues affect accurate and robust tracking performance. Thus, this study proposed a hemispherical marker rigid body to hold passive noncoplanar markers so that the markers could be identified by the camera, mitigating self-occlusion. The enlarged rotational range provides greater freedom for sonographers while performing examinations. The single-axis rotational and translational tracking performances of the system, equipped with the newly designed marker rigid body, were investigated and evaluated. Tracking with the designed marker rigid body achieved high tracking accuracy with 0.57° for the single-axis rotation and 0.01 mm for the single-axis translation for sensor distance between 1.5 and 2 m. In addition to maintaining high accuracy, the system also possessed an enhanced ability to capture over 99.76% of the motion data in the experiments. The results demonstrated that with the designed marker rigid body, the missing data were remarkably reduced from over 15% to less than 0.5%, which enables interpolation in the data postprocessing. An imaging test was further conducted, and the volume reconstruction of a four-month fetal phantom was demonstrated using the motion data obtained from the tracking system.}, number={6}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Cai, Qianqian and Peng, Chang and Lu, Jian-Yu and Prieto, Juan C. and Rosenbaum, Alan J. and Stringer, Jeffrey S. A. and Jiang, Xiaoning}, year={2021}, month={Jun}, pages={2155–2163} }
 @article{cai_wu_lu_prieto_rosenbaum_stringer_jiang_2021, title={Quantitative Study on Error Sensitivity in Ultrasound Probe Calibration with Hybrid Tracking}, ISSN={["1948-5719"]}, DOI={10.1109/IUS52206.2021.9593708}, abstractNote={Three-dimensional (3D) freehand ultrasound (US) imaging enabled by the external tracking system requires an accurate calibration process to transform the tracked motion information from the markers to the US frames. The previously proposed phantomless calibration method can be further improved using both optical tracking and image-based tracking. This study provides a quantitative analysis on the error sensitivity before implementing the image-based tracking during the calibration process. A linear relationship was found between the perturbation in imaging plane motion estimation and the error caused in the calibration solution. The error to perturbation ratio was within 0.5 in most cases and can reach up to around 0.9 in some poor cases. The overall analysis showed a good error tolerance for the hybrid tracking enabled US probe calibration.}, journal={INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS 2021)}, author={Cai, Qianqian and Wu, Tianfu and Lu, Jian-yu and Prieto, Juan C. and Rosenbaum, Alan J. and Stringer, Jeffrey S. A. and Jiang, Xiaoning}, year={2021} }
 @misc{peng_wu_kim_dai_jiang_2021, title={Recent Advances in Transducers for Intravascular Ultrasound (IVUS) Imaging}, volume={21}, ISSN={["1424-8220"]}, DOI={10.3390/s21103540}, abstractNote={As a well-known medical imaging methodology, intravascular ultrasound (IVUS) imaging plays a critical role in diagnosis, treatment guidance and post-treatment assessment of coronary artery diseases. By cannulating a miniature ultrasound transducer mounted catheter into an artery, the vessel lumen opening, vessel wall morphology and other associated blood and vessel properties can be precisely assessed in IVUS imaging. Ultrasound transducer, as the key component of an IVUS system, is critical in determining the IVUS imaging performance. In recent years, a wide range of achievements in ultrasound transducers have been reported for IVUS imaging applications. Herein, a comprehensive review is given on recent advances in ultrasound transducers for IVUS imaging. Firstly, a fundamental understanding of IVUS imaging principle, evaluation parameters and IVUS catheter are summarized. Secondly, three different types of ultrasound transducers (piezoelectric ultrasound transducer, piezoelectric micromachined ultrasound transducer and capacitive micromachined ultrasound transducer) for IVUS imaging are presented. Particularly, the recent advances in piezoelectric ultrasound transducer for IVUS imaging are extensively examined according to their different working mechanisms, configurations and materials adopted. Thirdly, IVUS-based multimodality intravascular imaging of atherosclerotic plaque is discussed. Finally, summary and perspectives on the future studies are highlighted for IVUS imaging applications.}, number={10}, journal={SENSORS}, author={Peng, Chang and Wu, Huaiyu and Kim, Seungsoo and Dai, Xuming and Jiang, Xiaoning}, year={2021}, month={May} }
 @article{goel_wu_zhang_kim_dayton_xu_jiang_2021, title={SAFETY EVALUATION OF A FORWARD-VIEWING INTRAVASCULAR TRANSDUCER FOR SONOTHROMBOLYSIS: AN IN VITRO AND EX VIVO STUDY}, volume={47}, ISSN={["1879-291X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85113414436&partnerID=MN8TOARS}, DOI={10.1016/j.ultrasmedbio.2021.07.018}, abstractNote={Recent in vitro work has revealed that a forward-viewing intravascular (FVI) transducer has sonothrombolysis applications. However, the safety of this device has yet to be evaluated. In this study, we evaluated the safety of this device in terms of tissue heating, vessel damage and particle debris size during sonothrombolysis using microbubbles or nanodroplets with tissue plasminogen activator, in both retracted and unretracted blood clots. The in vitro and ex vivo sonothrombolysis tests using FVI transducers revealed a temperature rise of less than 1°C, no vessel damage as assessed by histology and no downstream clot particles >500 µm. These in vitro and ex vivo results indicate that the FVI transducer poses minimal risk for sonothrombolysis applications and should be further evaluated in animal models.}, number={11}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Goel, Leela and Wu, Huaiyu and Zhang, Bohua and Kim, Jinwook and Dayton, Paul A. and Xu, Zhen and Jiang, Xiaoning}, year={2021}, month={Nov}, pages={3231–3239} }
 @misc{kim_kim_jiang_kim_2021, title={Static Force Measurement Using Piezoelectric Sensors}, volume={2021}, ISBN={1687-7268}, DOI={10.1155/2021/6664200}, abstractNote={In force measurement applications, a piezoelectric force sensor is one of the most popular sensors due to its advantages of low cost, linear response, and high sensitivity. Piezoelectric sensors effectively convert dynamic forces to electrical signals by the direct piezoelectric effect, but their use has been limited in measuring static forces due to the easily neutralized surface charge. To overcome this shortcoming, several static (either pure static or quasistatic) force sensing techniques using piezoelectric materials have been developed utilizing several unique parameters rather than just the surface charge produced by an applied force. The parameters for static force measurement include the resonance frequency, electrical impedance, decay time constant, and capacitance. In this review, we discuss the detailed mechanism of these piezoelectric-type, static force sensing methods that use more than the direct piezoelectric effect. We also highlight the challenges and potentials of each method for static force sensing applications.}, journal={JOURNAL OF SENSORS}, author={Kim, Kyungrim and Kim, Jinwook and Jiang, Xiaoning and Kim, Taeyang}, year={2021} }
 @article{peng_zhang_wu_dayton_xu_jiang_2021, title={Ultrasound Imaging-Guided Microbubble-Mediated Catheter-Directed Sonothrombolysis: An In-Vitro Study}, ISSN={["2378-377X"]}, DOI={10.1109/NMDC50713.2021.9677506}, abstractNote={Summary form only given, as follows. The complete presentation was not made available for publication as part of the conference proceedings. Deep vein thrombosis (DVT) is the formation of a blood clot in a deep vein, usually in the lower leg or thigh. The most serious complication of DVT is pulmonary embolism, which happens when part of the blood clot breaks off and travels through the bloodstream to the lungs, suddenly blocking blood flow. While using clot dissolving drugs is the standard treatment for DVT, thrombolytic drugs illustrate low thrombolysis efficiency and risk of bleeding side effects. Catheter-directed thrombolysis that uses a catheter to guide medication or a medical device to the site of a blood clot to dissolve the blockage, has become one of the most widely available and effective treatments for DVT. In this study, we combine a catheter-delivered forward-looking ultrasound transducer with microbubbles for microbubble-mediated catheter-directed sonothrombolysis, in order to reduce treatment time and increase treatment efficacy. A 600 kHz stack ultrasound transducer is developed and integrated into one lumen of an 8 Fr two-lumen catheter. During the sonothrombolysis procedure, the catheter location relative to the thrombus within a blood vessel is monitoring using ultrasound imaging guidance; the catheter tip distance to the blood clot is continuously controlled via a micro linear actuator with a speed of 100 μm/min.}, journal={2021 IEEE 16TH NANOTECHNOLOGY MATERIALS AND DEVICES CONFERENCE (NMDC 2021)}, author={Peng, Chang and Zhang, Bohua and Wu, Huaiyu and Dayton, Paul and Xu, Zhen and Jiang, Xiaoning}, year={2021} }
 @article{zhang_wu_jiang_2021, title={Ultrasound and Magnetic Dual-Mode Stacked Transducer for High-Frequency Magneto- Sonothrombolysis}, ISSN={["2378-377X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85125334509&partnerID=MN8TOARS}, DOI={10.1109/NMDC50713.2021.9677479}, abstractNote={Thrombosis usually occurs when a blood clot shapes within the blood vessel which may prevent the bloodstream through the body. Earlier microbubbles and tPA-mediated ultrasound thrombolysis usually had a relatively low efficacy for retracted clots owing to the limited penetration of agents into the condensed clot fibrin networks. Here we report the advancement of ultrasound and magnetic dual-mode stacked transducers, which can generate ultrasound wave and high frequency oscillating magnetic field to stimulate the superparamagnetic iron oxide nanoparticles (SPIONs) and microbubbles for enhanced tPA-mediated sonothrombolysis. The results showed that the combined effects of localized hyperthermia from the high-frequency oscillation of SPIONs and mechanical shock waves from ultrasound could effectively enhance the tPA-mediated sonothrombolysis efficacy.}, journal={2021 IEEE 16TH NANOTECHNOLOGY MATERIALS AND DEVICES CONFERENCE (NMDC 2021)}, author={Zhang, Bohua and Wu, Huaiyu and Jiang, Xiaoning}, year={2021} }
 @article{peng_chen_jiang_2021, title={Under-Display Ultrasonic Fingerprint Recognition With Finger Vessel Imaging}, volume={21}, ISSN={["1558-1748"]}, DOI={10.1109/JSEN.2021.3051975}, abstractNote={While fingerprint technology has been widely used in mobile devices for user identification, the existing fingerprint sensors can only capture 2D images of the fingerprint and are thus vulnerable to spoofing attacks using 2D replicas of fingerprint. Ultrasonic fingerprint recognition via imaging the structures beneath the human skin can be a promising approach for preventing spoofing attacks on fingerprint-based identification devices. In this study, under-display ultrasonic fingerprint recognition (UDUFR) was investigated for the first time via imaging a finger vessel underneath the fingerprint. A 40 MHz ultrasonic fingerprint sensor composed of PZT-5H piezoelectric active material was firstly developed, which demonstrated broad bandwidth (73.9%) and high loop sensitivity (−27.5 dB) for UDUFR applications. UDUFR experiments were performed to demonstrate the effectiveness of the proposed technique using a two-layer polydimethylsiloxane (PDMS) phantom which consists of a dummy fingerprint in the surface layer and a finger vessel mimicker in the inner layer. Electronic images of the fingerprint and finger vessel with a resolution of $500\times500$ DPI were successfully obtained. The results reported in this study open up new avenues for the next generation of robust and secure UDUFR technology.}, number={6}, journal={IEEE SENSORS JOURNAL}, author={Peng, Chang and Chen, Mengyue and Jiang, Xiaoning}, year={2021}, month={Mar}, pages={7412–7419} }
 @article{kim_deruiter_goel_xu_jiang_dayton_2020, title={A COMPARISON OF SONOTHROMBOLYSIS IN AGED CLOTS BETWEEN LOWBOILING-POINT PHASE-CHANGE NANODROPLETS AND MICROBUBBLES OF THE SAME COMPOSITION}, volume={46}, ISSN={["1879-291X"]}, DOI={10.1016/j.ultrasmedbio.2020.07.008}, abstractNote={We present enhanced cavitation erosion of blood clots exposed to low-boiling-point (−2°C) perfluorocarbon phase-change nanodroplets and pulsed ultrasound, as well as microbubbles with the same formulation under the same conditions. Given prior success with microbubbles as a sonothrombolysis agent, we considered that perfluorocarbon phase-change nanodroplets could enhance clot disruption further beyond that achieved with microbubbles. It has been hypothesized that owing to their small size and ability to penetrate into a clot, nanodroplets could enhance cavitation inside a blood clot and increase sonothrombolysis efficacy. The thrombolytic effects of lipid-shell-decafluorobutane nanodroplets were evaluated and compared with those of microbubbles with the same formulation, in an aged bovine blood clot flow model. Seven different pulsing schemes, with an acoustic intensity (ISPTA) range of 0.021–34.8 W/cm2 were applied in three different therapy scenarios: ultrasound only, ultrasound with microbubbles and ultrasound with nanodroplets (n = 5). Data indicated that pulsing schemes with 0.35 W/cm2 and 5.22 W/cm2 produced a significant difference (p < 0.05) in nanodroplet sonothrombolysis performance compared with compositionally identical microbubbles. With these excitation conditions, nanodroplet-mediated treatment achieved a 140% average thrombolysis rate over the microbubble-mediated case. We observed distinctive internal erosion in the middle of bovine clot samples from nanodroplet-mediated ultrasound, whereas the microbubble-mediated case generated surface erosion. This erosion pattern was supported by ultrasound imaging during sonothrombolysis, which revealed that nanodroplets generated cavitation clouds throughout a clot, whereas microbubble cavitation formed larger cavitation clouds only outside a clot sample.}, number={11}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Kim, Jinwook and DeRuiter, Ryan M. and Goel, Leela and Xu, Zhen and Jiang, Xiaoning and Dayton, Paul A.}, year={2020}, month={Nov}, pages={3059–3068} }
 @article{kim_kim_kim_jiang_2020, title={A Face-Shear Mode Piezoelectric Array Sensor for Elasticity and Force Measurement}, volume={20}, ISSN={["1424-8220"]}, DOI={10.3390/s20030604}, abstractNote={We present the development of a 6 × 6 piezoelectric array sensor for measuring elasticity and force. The proposed sensor employs an impedance measurement technique, sensing the acoustic load impedance of a target by measuring the electrical impedance shift of face-shear mode PMN–PT (lead magnesium niobate–lead titanate) single crystal elements. Among various modes of PMN–PT single crystals, the face-shear mode was selected due to its especially high sensitivity to acoustic loads. To verify the elasticity sensing performance, gelatin samples with different elastic moduli were prepared and tested. For the force measurement test, different magnitudes of force were loaded to the sensing layer whose acoustic impedance was varied with applied forces. From the experimental results, the fabricated sensor showed an elastic stiffness sensitivity of 23.52 Ohm/MPa with a resolution of 4.25 kPa and contact force sensitivity of 19.27 Ohm/N with a resolution of 5.19 mN. In addition, the mapping experiment of elasticity and force using the sensor array was successfully demonstrated.}, number={3}, journal={SENSORS}, author={Kim, Kyungrim and Kim, Taeyang and Kim, Jinwook and Jiang, Xiaoning}, year={2020}, month={Feb} }
 @misc{goel_jiang_2020, title={Advances in Sonothrombolysis Techniques Using Piezoelectric Transducers}, volume={20}, ISSN={["1424-8220"]}, DOI={10.3390/s20051288}, abstractNote={One of the great advancements in the applications of piezoelectric materials is the application for therapeutic medical ultrasound for sonothrombolysis. Sonothrombolysis is a promising ultrasound based technique to treat blood clots compared to conventional thrombolytic treatments or mechanical thrombectomy. Recent clinical trials using transcranial Doppler ultrasound, microbubble mediated sonothrombolysis, and catheter directed sonothrombolysis have shown promise. However, these conventional sonothrombolysis techniques still pose clinical safety limitations, preventing their application for standard of care. Recent advances in sonothrombolysis techniques including targeted and drug loaded microbubbles, phase change nanodroplets, high intensity focused ultrasound, histotripsy, and improved intravascular transducers, address some of the limitations of conventional sonothrombolysis treatments. Here, we review the strengths and limitations of these latest pre-clincial advancements for sonothrombolysis and their potential to improve clinical blood clot treatments.}, number={5}, journal={SENSORS}, author={Goel, Leela and Jiang, Xiaoning}, year={2020}, month={Mar} }
 @article{sheu_jiang_2020, title={Announcing IEEE Nanotechnology Magazine's New Editor-in-Chief and Co-Editor-in-Chief}, volume={14}, ISSN={["1942-7808"]}, DOI={10.1109/MNANO.2020.2980092}, abstractNote={EFFECTIVE 1 JANUARY 2020, PROF. Bing Sheu and Prof. Xiaoning Jiang have been serving as the editor-in-chief and coeditor-in-chief, respectively, of IEEE Nanotechnology Magazine. Their photos and biographies are included in this editorial. We offer our sincere appreciation to Prof. John T.W. Yeow, who served as the magazine’s editor-in-chief for the past six years and helped establish its significant success. IEEE Nanotechnology Magazine will continue its excellent service to the reader community by publishing high-quality and timely articles in special issues. Potential authors and/or guest editors for special issues are welcome to contact the editors directly.}, number={3}, journal={IEEE NANOTECHNOLOGY MAGAZINE}, author={Sheu, Bing and Jiang, Xiaoning}, year={2020}, month={Jun}, pages={3–4} }
 @article{ma_jiang_2020, title={Contrast-Enhanced Dual-Frequency Super-Harmonic Intravascular Ultrasound (IVUS) Imaging}, ISBN={["978-981-10-6306-0"]}, DOI={10.1007/978-981-10-6307-7_5}, journal={MULTIMODALITY IMAGING: FOR INTRAVASCULAR APPLICATION}, author={Ma, Jianguo and Jiang, Xiaoning}, year={2020}, pages={105–151} }
 @article{yu_kim_kim_barange_jiang_so_2020, title={Direct Acoustic Imaging Using a Piezoelectric Organic Light-Emitting Diode}, volume={12}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.0c05615}, abstractNote={Conventional ultrasonic imaging requires acoustic scanning over a target object using a piezoelectric transducer array, followed by signal processing to reconstruct the image. Here, we report a novel ultrasonic imaging device that can optically display an acoustic signal on the surface of a piezoelectric transducer. By fabricating an organic light-emitting diode (OLED) on top of a piezoelectric crystal (lead zirconate titanate, PZT), an acousto-optical piezoelectric OLED (p-OLED) transducer is realized, converting an acoustic wave profile directly to an optical image. Due to the integrated device architecture, the resulting p-OLED features a high acousto-optic conversion efficiency at the resonant ultrasound frequency, providing a piezoelectric field to drive the OLED. By incorporating an electrode array in the p-OLED, we demonstrate a novel tomographic ultrasound imaging device that is operated without a need for conventional signal processing.}, number={32}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Yu, Hyeonggeun and Kim, Jinwook and Kim, Howuk and Barange, Nilesh and Jiang, Xiaoning and So, Franky}, year={2020}, month={Aug}, pages={36409–36416} }
 @article{goel_wu_kim_zhang_kim_dayton_xu_jiang_2020, title={EXAMINING THE INFLUENCE OF LOW-DOSE TISSUE PLASMINOGEN ACTIVATOR ON MICROBUBBLE-MEDIATED FORWARD-VIEWING INTRAVASCULAR SONOTHROMBOLYSIS}, volume={46}, ISSN={["1879-291X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85086524519&partnerID=MN8TOARS}, DOI={10.1016/j.ultrasmedbio.2020.03.012}, abstractNote={Previous work revealed that a forward-viewing intravascular (FVI) transducer can be used for microbubble (MB)-mediated sonothrombolysis and that the clot lysis was dependent on MB concentration. This study examined the effects of combining tissue plasminogen activator (tPA) with MB-mediated FVI sonothrombolysis. In vitro clot lysis and passive cavitation experiments were conducted to study the effect of low-dose tPA in FVI sonothrombolysis with varying MB concentrations. Enhanced FVI sonothrombolysis was observed in cases in which ultrasound (US) was combined with tPA or MBs compared with control, tPA alone or US alone. The lysis rate of US + tPA + MBs was improved by up to 130%, 31% and 8% for MB concentrations of 106, 107 and 108 MBs/mL, respectively, compared with MBs + US alone. Changes in stable and inertial cavitation doses were observed, corresponding to changes in clot lysis in MB-mediated FVI sonothrombolysis with and without tPA.}, number={7}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Goel, Leela and Wu, Huaiyu and Kim, Howuk and Zhang, Bohua and Kim, Jinwook and Dayton, Paul A. and Xu, Zhen and Jiang, Xiaoning}, year={2020}, month={Jul}, pages={1698–1706} }
 @article{luo_chang_gao_chang_li_viehland_tian_jiang_2020, title={Multi-layered domain morphology in relaxor single crystals with nano-patterned composite electrode}, volume={182}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2019.10.017}, abstractNote={(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) single crystals, especially with compositions near its morphotropic phase boundary (MPB), have been employed for a broad range of applications such as ultrasound transducers, sensors, and actuators. To further enhance the properties of PMN-PT, electrode patterning, as a method of domain engineering, was proved to be an effective approach. In our previous report, a 200 nm grating pattern electrode (Ti/Au–MnOx) (nano-electrode) was prepared on one surface of PMN-PT crystal, exhibiting 30% d33 enhancement. In this work, the multi-layered domain morphology and the domain engineering from nano-electrode were characterized using piezoresponse force microscopy (PFM). A hypothetical domain engineering model for nano-electrodes is established to explain the experimental results as well as the property enhancement from the nano-electrode. The electrode patterning proves that the nano-scale modification can tune the macro-scale piezoelectric properties of the bulk material.}, journal={ACTA MATERIALIA}, author={Luo, Chengtao and Chang, Wei-Yi and Gao, Min and Chang, Chih-Hao and Li, Jiefang and Viehland, Dwight and Tian, Jian and Jiang, Xiaoning}, year={2020}, month={Jan}, pages={10–17} }
 @article{peng_chen_wang_shen_jiang_2020, title={P(VDF-TrFE) Thin-Film-Based Transducer for Under-Display Ultrasonic Fingerprint Sensing Applications}, volume={20}, ISSN={["1558-1748"]}, DOI={10.1109/JSEN.2020.2997375}, abstractNote={The use of fingerprint for biometric identification is one of the most prevalent authentication methods applied today in smartphones. In the course of pursuing narrow-bezel and full-screen display, the under-display fingerprint sensor is considered to be a user-friendly and practical solution for newer models of smartphone. While under-display optical fingerprint sensor has been commercially available in various smartphones, it demonstrates limitations such as sensitivity to humidity and contaminations including oil and water as well as easy to spoof. Ultrasonic fingerprint sensing has been proved to be able to overcome these limitations. In this study, P(VDF-TrFE) piezoelectric polymer-based transducer was reported, for the first time, for under-display ultrasonic fingerprint sensing applications. In specific, a 40 MHz ultrasonic transducer using a layer of <inline-formula> <tex-math notation="LaTeX">$10~\mu \text{m}$ </tex-math></inline-formula> thick P(VDF-TrFE) thin-film was designed, fabricated, and characterized. The under-display ultrasonic fingerprint sensing capability of the prototyped transducer was experimentally validated using phantoms of real fingerprint. Electronic images of fingerprint with resolution of <inline-formula> <tex-math notation="LaTeX">$500\times500$ </tex-math></inline-formula> DPI were obtained through under-display ultrasonic fingerprint sensing tests. The lateral resolution of the transducer was calculated to be <inline-formula> <tex-math notation="LaTeX">$\sim ~70~\mu \text{m}$ </tex-math></inline-formula>. The results of this study illustrate promising advances in under-display ultrasonic fingerprint sensing applications.}, number={19}, journal={IEEE SENSORS JOURNAL}, author={Peng, Chang and Chen, Mengyue and Wang, Hongchao and Shen, Jian and Jiang, Xiaoning}, year={2020}, month={Oct}, pages={11221–11228} }
 @article{shu_ke_fei_huang_wang_gong_jiang_wang_li_lei_et al._2020, title={Photoflexoelectric effect in halide perovskites}, volume={19}, ISSN={["1476-4660"]}, DOI={10.1038/s41563-020-0659-y}, abstractNote={Harvesting environmental energy to generate electricity is a key scientific and technological endeavour of our time. Photovoltaic conversion and electromechanical transduction are two common energy-harvesting mechanisms based on, respectively, semiconducting junctions and piezoelectric insulators. However, the different material families on which these transduction phenomena are based complicate their integration into single devices. Here we demonstrate that halide perovskites, a family of highly efficient photovoltaic materials1–3, display a photoflexoelectric effect whereby, under a combination of illumination and oscillation driven by a piezoelectric actuator, they generate orders of magnitude higher flexoelectricity than in the dark. We also show that photoflexoelectricity is not exclusive to halides but a general property of semiconductors that potentially enables simultaneous electromechanical and photovoltaic transduction and harvesting in unison from multiple energy inputs. Flexoelectricity is the ability of materials to generate electricity upon bending. Here it is demonstrated that adding light to mechanical oscillation enhances effective flexoelectric coefficients by orders of magnitude, with the halide perovskites showing the largest coefficients.}, number={6}, journal={NATURE MATERIALS}, author={Shu, Longlong and Ke, Shanming and Fei, Linfeng and Huang, Wenbin and Wang, Zhiguo and Gong, Jinhui and Jiang, Xiaoning and Wang, Li and Li, Fei and Lei, Shuijin and et al.}, year={2020}, month={Jun}, pages={605-+} }
 @article{kim_kim_morrow_jiang_2020, title={Stress Measurement of a Pressurized Vessel Using Ultrasonic Subsurface Longitudinal Wave With 1-3 Composite Transducers}, volume={67}, ISSN={["1525-8955"]}, url={https://doi.org/10.1109/TUFFC.2019.2941133}, DOI={10.1109/TUFFC.2019.2941133}, abstractNote={This article aims to develop a stress-sensing method for a pressurized vessel based on subsurface longitudinal (SSL) waves confined in a specific waveform by using 1–3 composite transducers. Although ultrasonic SSL waves have been commonly utilized for stress sensing, wave excitation under the predefined function using the composite-type transmitter is not well studied. In this article, composite-type transducers having a wide frequency bandwidth (> 60%) and a predominant thickness mode are utilized to enhance the signal intensity of the SSL wave and the accuracy of the sensor by incorporating a specific toneburst waveform. Finite element analysis demonstrates that the signal intensity of the composite-type transducer is up to 45.3% higher than that of a single-phase transducer. Pulse-echo tests reveal that the frequency bandwidth of the developed transducer reaches up to 60.7% and is, therefore, sufficient (> 57.0%) to transmit and receive Hanning-windowed toneburst signals. Results of stress sensing affirm a linear relationship between the time delay of SSL wave and the mechanical stress of a pressurized vessel (0.335 ns/MPa). Accordingly, the regression model is constructed via principal component regression (PCR) under temperature-varying condition. PCR has a less significant degree of error (0.62 MPa) compared to that of a typical least square regression (9.49 MPa).}, number={1}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Kim, Howuk and Kim, Taeyang and Morrow, Daniel and Jiang, Xiaoning}, year={2020}, month={Jan}, pages={158–166} }
 @article{ji_zhang_wang_huang_jiang_zhang_sang_guo_li_2020, title={Three-dimensional analyses of cells' positioning on the quadrupole-electrode microfluid chip considering the coupling effect of nDEP, ACEO, and ETF}, volume={165}, ISSN={["1873-4235"]}, DOI={10.1016/j.bios.2020.112398}, abstractNote={Microfluidic chips integrated with negative dielectrophoresis (nDEP) and electrochemical impedance spectroscopy have wide applications in cell sensing. Accurate analysis of the kinematics and dynamics of cells in the nDEP process is crucial to improve the positioning accuracy and electric cell-substrate impedance sensing (ECIS) performance. This paper reports employing the three-dimensional (3D) finite element model to analyze the coupling effects of electrokinetic flows (EF) such as alternating current electroosmosis (ACEO) and the electrothermal flow (ETF) on the nDEP positionings. On the quadrupole ECIS microfluid chip, three typical nDEP results are observed in the frequency range of 100 Hz-25 MHz and the amplitude range of 1-20 Vp-p. Simulations Based on the 3D hybrid model provide abundant kinematic information and show clear dynamic processes. Based on the discussion, the mechanisms of nDEP localizations and phase-tuning manipulations are proposed. It is found that the drag force could affect the particle's movement through the vortex of the flow field induced by ACEO and ETF, while the nDEP forces dominate the particles' locations on the substrate. Thus, the 3D dynamic-coupling analyses could help design the quadrupole-electrode microfluid chip and optimize the manipulation parameters in the experiment.}, journal={BIOSENSORS & BIOELECTRONICS}, author={Ji, Jianlong and Zhang, Jingjing and Wang, Jingxiao and Huang, Qing and Jiang, Xiaoning and Zhang, Wendong and Sang, Shengbo and Guo, Xiaoliang and Li, Shanshan}, year={2020}, month={Oct} }
 @article{gao_luo_chang_leung_tian_li_jiang_viehland_2019, title={Apparent phase stability and domain distribution of PMN-30PT single crystals with nanograted Au/MnOx electrodes}, volume={169}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2019.02.039}, abstractNote={X-ray diffraction (XRD) reciprocal space mapping (RSM) was used to investigate how nanograted electrodes affect the nanodomain distribution and average crystal structure in near-surface regions of poled Pb(Mg1/3Nb2/3)O3-30%PbTiO3 (PMN-30PT) single crystals. The RSM scans revealed a transverse broadening along the (H00) direction, which was quite different from that of either the rhombohedral (R) or monoclinic A (MA) phase. This broadening provides evidence of a non-uniform distribution of tilt angles between neighboring nanodomains, induced by a gradient in the applied electric field (E). Investigations of the front and back surfaces of the crystals revealed significant differences in the RSM scans. Gradients in the domain distribution and apparent symmetry may extend throughout the crystal thickness. The data evidence changes in the nanodomain distribution that results in adaptations of the average symmetry.}, journal={ACTA MATERIALIA}, author={Gao, Min and Luo, Chengtao and Chang, Wei-Yi and Leung, Chung Ming and Tian, Jian and Li, Jiefang and Jiang, Xiaoning and Viehland, D.}, year={2019}, month={May}, pages={28–35} }
 @article{kim_kim_chang_huang_jiang_dayton_2019, title={Candle-Soot Carbon Nanoparticles in Photoacoustics Advantages and challenges for laser ultrasound transmitters}, volume={13}, ISSN={["1942-7808"]}, DOI={10.1109/MNANO.2019.2904773}, abstractNote={This article provides a review of candle-soot nanoparticle (CSNP) composite laser ultrasound transmitters (LUTs) and compares and contrasts this technology with other carbon-composite designs. Among many carbon-based composite LUTs, a CSNP composite has demonstrated its advantages of maximum energy conversion and fabrication simplicity for developing highly efficient ultrasound transmitters. We focus on the advantages and challenges of the CSNP-composite transmitter in the areas of nanostructure design, fabrication procedure, and promising applications.}, number={3}, journal={IEEE NANOTECHNOLOGY MAGAZINE}, author={Kim, Jinwook and Kim, Howuk and Chang, Wei-Yi and Huang, Wenbin and Jiang, Xiaoning and Dayton, Paul A.}, year={2019}, month={Jun}, pages={13–28} }
 @article{li_shao_jiang_feng_2019, title={Deconvolution in Intravascular Ultrasound to Improve Lateral Resolution}, volume={41}, ISSN={["1096-0910"]}, DOI={10.1177/0161734619838456}, abstractNote={Intravascular ultrasound (IVUS) is an important diagnostic method for coronary disease. The lateral and axial resolutions of IVUS systems under study are typically ~120 and ~30 µm, respectively. The lateral resolution has a lower quality than the axial one and is restricted by the aperture size of transducers. In addition, this resolution is difficult to further improve physically. However, IVUS is inherently suitable for lateral deconvolution because of its circular imaging area. In this paper, magnitude-based deconvolution was demonstrated to be feasible in IVUS imaging to improve the lateral resolution. The deconvolution process was first simulated to determine the highest feasible resolution. Next, the method was applied to a real system to validate the feasibility. The lateral resolution was improved significantly, that is, 2°-separated targets could be discerned using a transducer with 4.2° –6 dB lateral resolution.}, number={4}, journal={ULTRASONIC IMAGING}, author={Li, Mingxia and Shao, Weiwei and Jiang, Xiaoning and Feng, Zhihua}, year={2019}, month={Jul}, pages={191–205} }
 @article{luo_wan_chang_yamashita_paterson_jones_jiang_2019, title={Effect of low-frequency alternating current poling on 5-mm-thick 0.7Pb(Mg1/3Nb2/3)O-3-0.3PbTiO(3) single crystals}, volume={115}, ISSN={["1077-3118"]}, DOI={10.1063/1.5127292}, abstractNote={Alternating current (electric field) poling (ACP) was applied on [001]-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-0.3PT) single crystal samples with dimensions of 5 × 1.25 × 1.25 mm3 (with electrodes on the 1.25 × 1.25 mm2 surfaces), and the influence of ACP frequency (fACP) was studied. Compared to those from traditional direct (electric field) poling samples, the piezoelectric coefficient (d33) and free dielectric constant (εT33/ε0) of ACP samples could gain up to a 67% increase to 3200 pC/N and 10 500, respectively. The influence of fACP was studied on two main aspects: saturated properties and dynamic saturation process. In general, ACP samples with lower fACP had higher saturated d33, εT33/ε0, and coupling factor k33, as well as lower dielectric loss and faster saturation speed. The ACP dynamics during the saturation process were studied by measuring the polarization-vs-electric field hysteresis loops (P-E loops). The P-E loops illustrated that the coercive field of ACP samples could be further tuned from 1.84 kV/cm to 3.03 kV/cm by changing fACP (0.1–10 Hz). This work demonstrated the enormous potential of ACP optimization in relaxor-PT single crystal-based low-frequency transducer applications.}, number={19}, journal={APPLIED PHYSICS LETTERS}, author={Luo, Chengtao and Wan, Haotian and Chang, Wei-Yi and Yamashita, Yohachi and Paterson, Alisa R. and Jones, Jacob and Jiang, Xiaoning}, year={2019}, month={Nov} }
 @article{luo_wan_chang_yamashita_paterson_jones_jiang_2019, title={Effect of low-frequency alternating current poling on 5-mm-thick 0.7Pb(Mg1/3Nb2/3)O-3-0.3PbTiO(3) single crystals (vol 115, 192904, 2019)}, volume={115}, ISSN={["1077-3118"]}, DOI={10.1063/1.5139662}, abstractNote={First Page}, number={26}, journal={APPLIED PHYSICS LETTERS}, author={Luo, Chengtao and Wan, Haotian and Chang, Wei-Yi and Yamashita, Yohachi and Paterson, Alisa R. and Jones, Jacob and Jiang, Xiaoning}, year={2019}, month={Dec} }
 @article{wan_luo_chang_yamashita_jiang_2019, title={Effect of poling temperature on piezoelectric and dielectric properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals under alternating current poling}, volume={114}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.5094362}, DOI={10.1063/1.5094362}, abstractNote={In this work, the piezoelectric and dielectric properties of [001]-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystals under alternating current poling (ACP) at different temperatures were studied. The piezoelectric coefficients (d33 ∼ 1930 pC/N, d31 ∼ −850 pC/N) and free dielectric permittivity (εT33/ε0 ∼ 7570) reached their highest values when the poling temperature (Tpoling) was 70 °C. Compared with traditional direct current electric field poling at 20 °C, 70 °C-ACP samples showed an enhancement of 40%, 35%, and 49% for d33, d31, and εT33/ε0, respectively. Meanwhile, d33 and εT33/ε0 were enhanced by about 9% when Tpoling increased from 20 °C to 70 °C under ACP, while d31 remained the same value and the dielectric loss was lowered from 0.29% to 0.22%. Moreover, ACP samples with different Tpoling have similar electromechanical coupling factors (k31 ∼ 0.44, kt ∼ 0.60). A discussion of the mechanism for the ACP enhancement was based on the domain observation using piezoresponse force microscopy, and the results showed that the domain densities of ACP samples with different Tpoling were positively correlated with their piezoelectric properties. This work demonstrated the enormous potential of ACP optimization for relaxor-PT single crystal applications.}, number={17}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Wan, Haotian and Luo, Chengtao and Chang, Wei-Yi and Yamashita, Yohachi and Jiang, Xiaoning}, year={2019}, month={Apr}, pages={172901} }
 @article{ji_li_chen_wang_jiang_zhuo_liu_yang_gu_sang_et al._2019, title={In situ fabrication of organic electrochemical transistors on a microfluidic chip}, volume={12}, ISSN={["1998-0000"]}, DOI={10.1007/s12274-019-2462-0}, number={8}, journal={NANO RESEARCH}, author={Ji, Jianlong and Li, Mangmang and Chen, Zhaowei and Wang, Hongwang and Jiang, Xiaoning and Zhuo, Kai and Liu, Ying and Yang, Xing and Gu, Zhen and Sang, Shengbo and et al.}, year={2019}, month={Aug}, pages={1943–1951} }
 @article{qi_huang_fu_li_zhou_jiang_2019, title={Modeling of the flexoelectric annular microplate based on strain gradient elasticity theory}, volume={26}, ISSN={["1537-6532"]}, DOI={10.1080/15376494.2018.1455935}, abstractNote={ABSTRACT A size-dependent annular microplate model is established based on the isotropic flexoelectric theory, which considering the effects of strain gradient, polarization gradient, and microscopic electrical field gradient. The displacement mode of the Kirchhoff plate theory is used to obtain the detailed expressions of the electric enthalpy, dynamic energy, and the work done by external forces. The governing equations, boundary conditions, and initial conditions are derived using the Hamilton's principle. By solving the governing equations with only mechanical and only electrical boundary conditions, the analytical solutions of deflection and polarization in the static direct and converse flexoelectric responses are obtained, respectively. Meanwhile, the free vibration problem is also solved. Finally, based on the analytical solutions, some numerical results are given to illustrate the unique flexoelectric properties of the annular microplate compared with the solid circular microplate and influence of the strain gradient elastic effect on the static direct and converse flexoelectric responses as well as the natural frequency.}, number={23}, journal={MECHANICS OF ADVANCED MATERIALS AND STRUCTURES}, author={Qi, Lu and Huang, Shujin and Fu, Guangyang and Li, Anqing and Zhou, Shenjie and Jiang, Xiaoning}, year={2019}, month={Dec}, pages={1958–1968} }
 @article{zhang_lv_zhang_huang_wong_yau_chen_wen_jiang_zeng_et al._2019, title={Modulating the Electrical Transport in the Two-Dimensional Electron Gas at LaAlO3/SrTiO3 Heterostructures by Interfacial Flexoelectricity}, volume={122}, ISSN={["1079-7114"]}, DOI={10.1103/PhysRevLett.122.257601}, abstractNote={Thin film flexoelectricity is attracting more attention because of its enhanced effect and potential application in electronic devices. Here we find that a mechanical bending induced flexoelectricity significantly modulates the electrical transport properties of the interfacial two-dimensional electron gas (2DEG) at the LaAlO_{3}/SrTiO_{3} (LAO/STO) heterostructure. Under variant bending states, both the carrier density and mobility of the 2DEG are changed according to the flexoelectric polarization direction, showing an electric field effect modulation. By measuring the flexoelectric response of LAO, it is found that the effective flexoelectricity in the LAO thin film is enhanced by 3 orders compared to its bulk. These results broaden the horizon of study on the flexoelectricity effect in the hetero-oxide interface and more research on the oxide interfacial flexoelectricity may be stimulated.}, number={25}, journal={PHYSICAL REVIEW LETTERS}, author={Zhang, Fan and Lv, Peng and Zhang, Yiteng and Huang, Shujin and Wong, Chi-Man and Yau, Hei-Man and Chen, Xinxin and Wen, Zheng and Jiang, Xiaoning and Zeng, Changgan and et al.}, year={2019}, month={Jun} }
 @article{kim_chang_kim_jiang_2019, title={Narrow band photoacoustic lamb wave generation for nondestructive testing using candle soot nanoparticle patches}, volume={115}, ISSN={["1077-3118"]}, DOI={10.1063/1.5100292}, abstractNote={The generation of ultrasonic surface waves with a photoacoustic-laser-source has become useful for the noncontact nondestructive testing and evaluation (NDT&E) of materials and structures. In this work, a hybrid ultrasound based NDT&E method is proposed based on the photoacoustic-laser-source as a noncontact Lamb wave generator by incorporating a line-arrayed patterned candle soot nanoparticle-polydimethylsiloxane (CSNPs-PDMS) patch as the signal amplifier and with a narrow bandwidth. The CSNP-PDMS composite has been investigated as the functional patch for its laser energy absorption efficiency, fast thermal diffusion, and large thermoelastic expansion capabilities. The signal amplitude (in mW) from the CSNP-PDMS patch exhibits 2.3 times higher amplitude than the no patch condition and a narrower bandwidth than other conditions. Furthermore, improvement in the sensitivity is also achieved through the selection of the aluminum nitride sensing system. The overall combination of the Lamb wave generation and receiver-sensing system in this study is found to be very promising for a broad range of noncontact NDT&E applications.}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={Kim, Taeyang and Chang, Wei-Yi and Kim, Howuk and Jiang, Xiaoning}, year={2019}, month={Sep} }
 @article{zhang_kim_wu_gao_jiang_2019, title={Sonothrombolysis with magnetic microbubbles under a rotational magnetic field}, volume={98}, ISSN={["1874-9968"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85067191804&partnerID=MN8TOARS}, DOI={10.1016/j.ultras.2019.06.004}, abstractNote={Thrombosis is an extremely critical clinical condition where a clot forms inside a blood vessel which blocks the blood flow through the cardiovascular system. Previous sonothrombolysis methods using ultrasound and microbubbles (MBs) often have a relatively low lysis rate due to the low microbubbles concentration at clot region caused by blood flow in the vessel. To solve this problem, the magnetic microbubbles (MMBs) that can be retained by an outer magnetic field against blood flow are used in this study. Here we report the development of a new method using the rotational magnetic field to trap and vibrate magnetic microbubbles at target clot region and then using an intravascular forward-looking ultrasound transducer to activate them acoustically. In this study, we investigated the influence of different blood flow conditions, vessel occlusion conditions (partial and fully occluded), clot ages (fresh, retracted), ultrasound parameters (input voltage, duty cycle) and rotational magnetic field parameters (amplitude, frequency) on the thrombolysis rate. The results showed that the additional use of magnetic microbubbles significantly enhances in vitro lysis of blood clot.}, journal={ULTRASONICS}, author={Zhang, Bohua and Kim, Howuk and Wu, Huaiyu and Gao, Yu and Jiang, Xiaoning}, year={2019}, month={Sep}, pages={62–71} }
 @article{kim_chang_kim_huang_jiang_2019, title={Stress Measurement of a Pressurized Vessel Using Candle Soot Nanocomposite Based Photoacoustic Excitation}, volume={10971}, ISSN={["1996-756X"]}, DOI={10.1117/12.2515211}, abstractNote={This article aims to develop a pressure sensing method by utilizing both a contacting active sensor and a non-contacting laser ultrasound transmitter. An overloaded stress in an industrial pressure tank such as a nuclear reactor may cause a catastrophic explosion; thus, it is essential to monitor the mechanical stress in a reliable manner for the structural safety. Among many different types of stress sensing methods, ultrasound sensing has been attractive due to its non-invasive measurement feature. For the recent decades, subsurface longitudinal (SSL) ultrasonic wave has been widely used since it is not only less dependent on the internal medium and the surface condition, but also has the fastest wave speed without wave distortion. In our work, laser source and Aluminum nitride (AlN) wafer are used to generate and to receive SSL ultrasonic waves, respectively. In order to increase the photoacoustic efficacy, a composite of carbon-soot nanoparticles (CSNP) and polydimethylsiloxane (PDMS) was attached onto the intermediate wedge at the transmitter side. The photoacoustic experiment results demonstrate a reasonable linear relationship between the stress level and the time-of-flight variation of the propagated wave signal.}, journal={NONDESTRUCTIVE CHARACTERIZATION AND MONITORING OF ADVANCED MATERIALS, AEROSPACE, CIVIL INFRASTRUCTURE, AND TRANSPORTATION XIII}, author={Kim, Ho-Wuk and Chang, Wei-Yi and Kim, Taeyang and Huang, Shujin and Jiang, Xiaoning}, year={2019} }
 @article{li_kim_wang_kasoji_lindsey_dayton_jiang_2018, title={A Dual-Frequency Colinear Array for Acoustic Angiography in Prostate Cancer Evaluation}, volume={65}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2018.2872911}, abstractNote={Approximately 80% of men who reach 80 years of age will have some form of prostate cancer. The challenge remains to differentiate benign and malignant lesions. Based on recent research, acoustic angiography, a novel contrast-enhanced ultrasound imaging technique, can provide high-resolution visualization of tissue microvasculature and has demonstrated the ability to differentiate vascular characteristics between healthy and tumor tissue in preclinical studies. We hypothesize that transrectal acoustic angiography may enhance the assessment of prostate cancer. In this paper, we describe the development of a dual frequency, dual-layer colinear array transducer for transrectal acoustic angiography. The probe consists of 64 transmitting (TX) elements with a center frequency of 3 MHz and 128 receiving (RX) elements with a center frequency of 15 MHz. The dimensions of the array are 18 mm in azimuth and 9 mm in elevation. The pitch is  $280~\mu \text{m}$  for TX elements and 140  $\mu \text{m}$  for RX elements. Pulse-echo tests of TX/RX elements and aperture acoustic field measurements were conducted, and both results were compared with the simulation results. Real-time contrast imaging was performed using a Verasonics system and a tissue-mimicking phantom. Nonlinear acoustic responses from microbubble contrast agents at a depth of 35 mm were clearly observed. In vivo imaging in a rodent model demonstrated the ability to detect individual vessels underneath the skin. These results indicate the potential use of the array described herein for acoustic angiography imaging of prostate tumor and identification of regions of neovascularization for the guidance of prostate biopsies.}, number={12}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Li, Sibo and Kim, Jinwook and Wang, Zhuochen and Kasoji, Sandeep and Lindsey, Brooks D. and Dayton, Paul A. and Jiang, Xiaoning}, year={2018}, month={Dec}, pages={2418–2428} }
 @article{chang_chung_luo_kim_yamashita_jones_jiang_2018, title={Dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O-3-0.3 PbTiO3 single crystal poled using alternating current}, volume={6}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2018.1498812}, abstractNote={ABSTRACT In this paper, 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-30%PT) single crystal samples were poled using an alternating current (electric field) poling (ACP) method. Compared to the traditional poling method, the piezoelectric coefficient, free and clamped dielectric constants were improved more than 21%. X-ray diffraction result suggests the existence of monoclinic phase (MA) in ACP samples and piezoresponse force microscopy (PFM) result further depicts the finer engineered domain structures. The ACP sample also showed the unique phase transition sequences during the depoling process. Our work could provide a novel domain engineered method to enhance piezoelectric properties of PMN-PT single crystal. GRAPHICAL ABSTRACT IMPACT STATEMENT Piezoelectric and dielectric properties of relaxor-PT single crystals can be significantly enhanced by employing the new alternating current poling method, attributing to the unique heterogenous domain structure containing unprecedented domain wall density.}, number={10}, journal={MATERIALS RESEARCH LETTERS}, author={Chang, Wei-Yi and Chung, Ching-Chang and Luo, Chengtao and Kim, Taeyang and Yamashita, Yohachi and Jones, Jacob L. and Jiang, Xiaoning}, year={2018}, pages={537–544} }
 @article{yuan_sang_sun_qi_chang_zhang_yang_jiang_cao_2018, title={Domain engineering and full matrix material constants of the [111](c)-poled 0.63Pb(Mg1/3Nb2/3)-0.37PbTiO(3) single crystal}, volume={20}, ISSN={["1466-8033"]}, DOI={10.1039/c8ce00831k}, abstractNote={Domain engineering was performed on a [111]c-oriented tetragonal ferroelectric 0.63Pb(Mg1/3Nb2/3)-0.37PbTiO3 (PMN-0.37PT) single crystal in order to achieve better piezoelectric properties.}, number={33}, journal={CRYSTENGCOMM}, author={Yuan, Zhongyuan and Sang, Shijing and Sun, Enwei and Qi, Xudong and Chang, Wei-Yi and Zhang, Rui and Yang, Bin and Jiang, Xiaoning and Cao, Wenwu}, year={2018}, month={Sep}, pages={4745–4751} }
 @article{nguyen_nanthakumar_zhuang_wriggers_jiang_rabczuk_2018, title={Dynamic flexoelectric effect on piezoelectric nanostructures}, volume={71}, ISSN={["1873-7285"]}, DOI={10.1016/j.euromechsol.2018.06.002}, abstractNote={Flexoelectricity, which represents the spontaneous electric polarization induced by the strain gradient, is a universal electromechanical coupling effect regardless of symmetry in all dielectric material. In solid dielectric material, the contribution from flexoelectricity can be due to four related phenomena: static and dynamic bulk flexoelectricity, surface flexoelectricity and surface piezoelectricity. While the surface flexoelectric effect can be negligible, the magnitude of the remaining three phenomena are comparable. Presently, the role of the static bulk flexoelectric and surface piezoelectric effects in the energy harvesters has been intensively studied, the contribution from dynamic flexoelectric effect remains unclear. In this work, based on the conventional beam theory, equations of motion considering dynamic flexoelectric effect are investigated. Consequently, the free vibration of the simply supported beam is studied in order to examine the influence of the dynamic flexoelectricity on natural frequency. From the numerical studies, it is found that dynamic flexoelectric effect is more influential on thick beam model and higher vibration modes. In addition, the results show that the relation between the static and dynamic flexoelectric coefficients can also alter the free vibration response.}, journal={EUROPEAN JOURNAL OF MECHANICS A-SOLIDS}, author={Nguyen, B. H. and Nanthakumar, S. S. and Zhuang, X. and Wriggers, P. and Jiang, X. and Rabczuk, T.}, year={2018}, pages={404–409} }
 @article{chang_zhang_kim_huang_bagal_chang_fang_wu_jiang_2018, title={Evaluation of Photoacoustic Transduction Efficiency of Candle Soot Nanocomposite Transmitters}, volume={17}, ISSN={["1941-0085"]}, url={https://doi.org/10.1109/TNANO.2018.2845703}, DOI={10.1109/TNANO.2018.2845703}, abstractNote={Candle soot nanoparticles (CSNP) and polydimethyl-siloxane (PDMS) composite has shown the highly efficient photoacoustic transduction owing to their high light absorption coefficient and low interfacial thermal resistance. In this study, we report the effect of candle soot structure and thickness on the photoacoustic transduction efficiency. Optical properties of the CSNP/PDMS nanocomposites were characterized through both experimental measurements and finite difference time domain analysis in the visible wavelength range, indicating that the carbon volume fraction and thickness of CS/PDMS composite are highly relevant with light absorption. With a low laser energy input ( <inline-formula><tex-math notation="LaTeX">$< {\text{1 mJ/pulse}}$</tex-math></inline-formula>), the CS/PDMS composite with 2.15 <italic>μ</italic>m thickness exerts an output pressure of 3.78 MPa and a conversion efficiency of <inline-formula><tex-math notation="LaTeX">${\text{9.69}}\,\times \,{\text{10}}^{- 3}$</tex-math> </inline-formula>, which is two orders of magnitude higher than previously reported results.}, number={5}, journal={IEEE TRANSACTIONS ON NANOTECHNOLOGY}, publisher={Institute of Electrical and Electronics Engineers (IEEE)}, author={Chang, Wei-Yi and Zhang, Xu A. and Kim, Jinwook and Huang, Wenbin and Bagal, Abhijeet and Chang, Chih-Hao and Fang, Tiegang and Wu, Hanchang Felix and Jiang, Xiaoning}, year={2018}, month={Sep}, pages={985–993} }
 @article{huang_yau_yu_qi_so_dai_jiang_2018, title={Flexoelectricity in a metal/ferroelectric/semiconductor heterostructure}, volume={8}, ISSN={["2158-3226"]}, DOI={10.1063/1.5031162}, abstractNote={The flexoelectricity in a 100 nm-thick BaTiO3 (BTO) thin film based metal/ferroelectric insulator/semiconductor (MFS) heterostructure was reported in this letter. The transverse flexoelectric coefficient of the BTO thin film in the heterojunction structure was measured to be 287-418 μC/m at room temperature, and its temperature dependence shows that the flexoelectric effect in the BTO thin film was dominated in the paraelectric phase. We showed that the BTO thin film capacitance could be controlled at multi-levels by introducing ferroelectric and flexoelectric polarization in the film. These results are promising for understanding of the flexoelectricity in epitaxial ferroelectric thin films and practical applications of the enhanced flexoelectricity in nanoscale devices.}, number={6}, journal={AIP ADVANCES}, author={Huang, Shujin and Yau, Hei-Man and Yu, Hyeonggeun and Qi, Lu and So, Franky and Dai, Ji-Yan and Jiang, Xiaoning}, year={2018}, month={Jun} }
 @misc{huang_qi_huang_shu_zhou_jiang_2018, title={Flexoelectricity in dielectrics: Materials, structures and characterizations}, volume={8}, ISSN={["2010-1368"]}, DOI={10.1142/s2010135x18300025}, abstractNote={ Flexoelectricity in dielectrics suggests promising smart structures for sensors, actuators and transducers. In this review, dielectric materials, structures and the associated flexoelectric characterization methods are presented. First of all, we review structures and methods to measure different flexoelectric coefficients, including [Formula: see text], etc., via direct or converse flexoelectric effect. The flexoelectric materials in the form of bulk, thin films and 2D materials and the reported flexoelectric properties of these dielectrics will then be discussed. Semiconductor materials and the associated flexoelectric studies will also be reviewed. The progress of flexoelectric device study will next be presented, followed by the flexoelectricity research challenges and future trend. }, number={2}, journal={JOURNAL OF ADVANCED DIELECTRICS}, author={Huang, Shujin and Qi, Lu and Huang, Wenbin and Shu, Longlong and Zhou, Shenjie and Jiang, Xiaoning}, year={2018}, month={Apr} }
 @article{kim_wu_jiang_2018, title={MINIATURIZED FOCUSED ULTRASOUND TRANSDUCERS FOR INTRAVASCULAR THERAPIES}, ISBN={["978-0-7918-5836-3"]}, DOI={10.1115/imece2017-72426}, abstractNote={Intravascular ultrasound approach has shown its advantages for thrombectomy. Catheter-directed ultrasound techniques have realized safe therapies by suppressing mechanical contact and penetration of excessive ultrasound energy through the tissue. One limitation of this approach is the lack of the sufficient ultrasound energy for fast thrombectomy because typical catheter-mounted transducers have high-frequency and low acoustic power. In this work, we aim to resolve this problem by designing miniaturized focused ultrasound transducers for improved therapeutic efficacy, which can generate low-frequency, sufficient pressure output within the confined insonation beam. This study builds upon our previous initial design of sub-megahertz, forward-looking, focused ultrasound transducers for preliminary in vitro study on microbubble-mediated thrombolysis. 650 kHz, forward-looking, concave-aperture ultrasound transducers were designed and mounted on 5–6 F catheters. The effect of design factors including aperture diameter, radius-of-curvature, and concave lens acoustic impedance on focusing performance were analyzed by using finite element analysis. Although the theoretical prerequisites for ideal beam focusing were not fulfilled due to the spatial limitation, the simulation results showed that practical design of the concave lens with the small geometrical aperture still enables to generate confined beam with a reasonable focal gain. Experimental validation results confirmed that the focal gain of 9 dB can be achievable. The measured transmitting sensitivity of the concave aperture transducer is 22.5 kPa/Vpp.}, journal={PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2017, VOL 3}, author={Kim, Jinwook and Wu, Huaiyu and Jiang, Xiaoning}, year={2018} }
 @article{qi_huang_fu_zhou_jiang_2018, title={On the mechanics of curved flexoelectric microbeams}, volume={124}, ISSN={["1879-2197"]}, DOI={10.1016/j.ijengsci.2017.11.022}, abstractNote={Based on the flexoelectric theory incorporating strain gradient and polarization gradient, a flexoelectric curved microbeam model is established. The governing equations, boundary conditions and initial conditions are derived by Hamilton's principle. Both the static bending and natural vibration problems are solved. The direct and converse flexoelectric responses are numerically analyzed. In the direct flexoelectric response, more collected charges are expected in the beam with larger original curvature for simply supported boundary, but the opposite is true for clamped boundary. In the converse flexoelectric response, the voltage-induced bending exists even in a clamped curved beam while it is not the case for a clamped straight beam and larger original curvature always implies larger deflection for both boundary conditions. In addition, the strain gradient elastic effect is found to reduce both the flexoelectric responses especially when the thickness is comparable to the length scale parameter associated with strain gradient.}, journal={INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE}, author={Qi, Lu and Huang, Shujin and Fu, Guangyang and Zhou, Shenjie and Jiang, Xiaoning}, year={2018}, month={Mar}, pages={1–15} }
 @article{chang_chung_yuan_chang_tian_viehland_li_jones_jiang_2018, title={Patterned nano-domains in PMN-PT single crystals}, volume={143}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2017.10.016}, abstractNote={The domain structure, dielectric, and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) single crystals with nanocomposite electrode, which includes MnOx semiconductor nanogratings and a Ti/Au conductive layer, were studied in this paper. These artificial MnOx nanogratings can alter the electric field distribution and then enhance the domain density. PMN-PT crystals with Ti/Au-MnOx nanocomposite electrodes showed high piezoelectric constant of 2250 p.m./V and dielectric constant of 5400 at 1 kHz, respectively. Compared to ones with conventional planar electrodes, the piezoelectric and dielectric constants of the samples with nanocomposite electrodes were increased 36.7% and 38.3%, respectively. Piezoresponse force microscopy (PFM) images revealed the domain pattern near the electrode/single crystal interface. A linear domain structure induced by the MnOx nanocomposite electrode was found in the samples with thickness less than 200 μm. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) results showed the diffusion of Mn about 300 nm in depth in PMNPT crystal after heat treatment during MnOx nanocomposite electrode. It is believed that the localized high electric fields induced by fringe effects caused by the nanocomposite electrode can enhance nucleation of new domains, and that diffusion from the patterned Mn layer may also lead to an enhancement in domain wall mobility. Our findings open up a new domain engineering technique for tailoring the dielectric and piezoelectric properties of PMN-PT single crystals.}, journal={Acta Materialia}, author={Chang, W.-Y. and Chung, C.-C. and Yuan, Z. and Chang, C.-H. and Tian, J. and Viehland, D. and Li, J.-F. and Jones, J.L. and Jiang, X.}, year={2018}, month={Jan}, pages={166–173} }
 @article{berik_chang_jiang_2018, title={Piezoelectric torsional actuation in d(36) shear-mode PMN-PT single crystals}, volume={10598}, ISSN={["1996-756X"]}, DOI={10.1117/12.2292672}, abstractNote={This paper presents an experimental and numerical characterization of a piezoelectric d36 shear-based torsion actuator made of xPb(Mg1/3Nb2/3)O3-(1-x)PbTiO3 (PMN-PT) single crystals embedded between Polydimethylsiloxane (PDMS) layers. The generated rate of twist value of the piezoelectric d36-mode PMN-PT single crystal composite torsion actuator was obtained using a laser vibrometer from the maximum detected transverse deflection measurement. The quasi–static torsion actuation experiments were conducted on the piezoelectric d36 torsion actuator by applying different AC voltages at 1 Hz. The experimental benchmark was further modelled by Finite Element (FE) code ABAQUS® using three dimensional (3D) piezoelectric finite elements. The experimental results and Finite Element computations showed good agreement. Findings reveal that more rate of twist is produced by PMN-PT single crystals in comparison to piezoceramic alternatives. This piezoelectric PMN-PT d36-mode composite torsion actuator can be effectively used in torsional deformation control.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2018}, author={Berik, Pelin and Chang, Wei-Yi and Jiang, Xiaoning}, year={2018} }
 @article{wang_martin_dayton_jiang_2018, title={Real-time ultrasound angiography using superharmonic dual-frequency (2.25 MHz/30 MHz) cylindrical array: In vitro study}, volume={82}, ISSN={["1874-9968"]}, DOI={10.1016/j.ultras.2017.09.012}, abstractNote={Recent studies suggest that dual-frequency intravascular ultrasound (IVUS) transducers allow detection of superharmonic bubble signatures, enabling acoustic angiography for microvascular and molecular imaging. In this paper, a dual-frequency IVUS cylindrical array transducer was developed for real-time superharmonic imaging. A reduced form-factor lateral mode transmitter (2.25MHz) was used to excite microbubbles effectively at 782kPa with single-cycle excitation while still maintaining the small size and low profile (5Fr) (3Fr=1mm) for intravascular imaging applications. Superharmonic microbubble responses generated in simulated microvessels were captured by the high frequency receiver (30MHz). The axial and lateral full-width half-maximum of microbubbles in a 200-μm-diameter cellulose tube were measured to be 162μm and 1039μm, respectively, with a contrast-to-noise ratio (CNR) of 16.6dB. Compared to our previously reported single-element IVUS transducers, this IVUS array design achieves a higher CNR (16.6dBvs 11dB) and improved axial resolution (162μmvs 616μm). The results show that this dual-frequency IVUS array transducer with a lateral-mode transmitter can fulfill the native design requirement (∼3-5Fr) for acoustic angiography by generating nonlinear microbubble responses as well as detecting their superharmonic responses in a 5Fr form factor.}, journal={ULTRASONICS}, author={Wang, Zhuochen and Martin, K. Heath and Dayton, Paul A. and Jiang, Xiaoning}, year={2018}, month={Jan}, pages={298–303} }
 @misc{zhang_li_yu_jiang_lee_luo_shrout_2018, title={Recent Developments in Piezoelectric Crystals}, volume={55}, ISSN={["2234-0491"]}, DOI={10.4191/kcers.2018.55.5.12}, abstractNote={Piezoelectric materials are essential parts of the electronics and electrical equipment used for consumer and industrial applications, such as ultrasonic piezoelectric transducers, sensors, actuators, transformers, and resonators. In this review, the development of piezoelectric materials and the figures of merit for various electromechanical applications are surveyed, focusing on piezoelectric crystals, i.e., the high-performance relaxor-PbTiO3-based perovskite ferroelectric crystals and nonferroelectric hightemperature piezoelectric crystals. The uniqueness of these crystals is discussed with respect to different usages. Finally, the existing challenges and perspective for the piezoelectric crystals are discussed, with an emphasis on the temperature-dependent properties, from cryogenic temperatures up to the ultrahigh-temperature usage range.}, number={5}, journal={JOURNAL OF THE KOREAN CERAMIC SOCIETY}, author={Zhang, Shujun and Li, Fei and Yu, Fapeng and Jiang, Xiaoning and Lee, Ho-Yong and Luo, Jun and Shrout, T. R.}, year={2018}, month={Sep}, pages={419–439} }
 @article{wang_martin_huang_dayton_jiang_2017, title={Contrast Enhanced Superharmonic Imaging for Acoustic Angiography Using Reduced Form-Factor Lateral Mode Transmitters for Intravascular and Intracavity Applications}, volume={64}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2016.2619687}, abstractNote={Techniques to image the microvasculature may play an important role in imaging tumor-related angiogenesis and vasa vasorum associated with vulnerable atherosclerotic plaques. However, the microvasculature associated with these pathologies is difficult to detect using traditional B-mode ultrasound or even harmonic imaging due to small vessel size and poor differentiation from surrounding tissue. Acoustic angiography, a microvascular imaging technique that utilizes superharmonic imaging (detection of higher order harmonics of microbubble response), can yield a much higher contrast-to-tissue ratio than second harmonic imaging methods. In this paper, two dual-frequency transducers using lateral mode transmitters were developed for superharmonic detection and acoustic angiography imaging in intracavity applications. A single element dual-frequency intravascular ultrasound transducer was developed for concept validation, which achieved larger signal amplitude, better contrast-to-noise ratio (CNR), and pulselength compared to the previous work. A dual-frequency [Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>]–x[PbTiO<sub>3</sub>] array transducer was then developed for superharmonic imaging with dynamic focusing. The axial and lateral sizes of the microbubbles in a 200-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> tube were measured to be 269 and <inline-formula> <tex-math notation="LaTeX">$200~\mu \text{m}$ </tex-math></inline-formula>, respectively. The maximum CNR was calculated to be 22 dB. These results show that superharmonic imaging with a low frequency lateral mode transmitter is a feasible alternative to thickness mode transmitters when the final transducer size requirements dictate design choices.}, number={2}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Wang, Zhuochen and Martin, K. Heath and Huang, Wenbin and Dayton, Paul A. and Jiang, Xiaoning}, year={2017}, month={Feb}, pages={311–319} }
 @article{lindsey_kim_dayton_jiang_2017, title={Dual-Frequency Piezoelectric Endoscopic Transducer for Imaging Vascular Invasion in Pancreatic Cancer}, volume={64}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2017.2702010}, abstractNote={Cancers of the pancreas have the poorest prognosis among all cancers, as many tumors are not detected until surgery is no longer a viable option. Surgical viability is typically determined via endoscopic ultrasound imaging. However, many patients who may be eligible for resection are not offered surgery due to diagnostic challenges in determining vascular or lymphatic invasion. In this paper, we describe the development of a dual-frequency piezoelectric transducer for rotational endoscopic imaging designed to transmit at 4 MHz and receive at 20 MHz in order to image microbubble-specific superharmonic signals. Imaging performance is assessed in a tissue-mimicking phantom at depths from 1 cm [contrast-to-tissue ratio (CTR) = 21.6 dB] to 2.5 cm (CTR = 11.4 dB), in ex vivo porcine vessels, and in vivo in a rodent. The prototyped 1.1-mm aperture transducer demonstrates contrast-specific imaging of microbubbles in a 200- $\mu \text{m}$ -diameter tube through the wall of a 1-cm-diameter porcine artery, suggesting such a device may enable direct visualization of small vessels from within the lumen of larger vessels such as the portal vein or superior mesenteric vein.}, number={7}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Lindsey, Brooks D. and Kim, Jinwook and Dayton, Paul A. and Jiang, Xiaoning}, year={2017}, month={Jul}, pages={1078–1086} }
 @article{kim_lindsey_li_dayton_jiang_2017, title={Dual-Frequency Transducer with a Wideband PVDF Receiver for Contrast-Enhanced, Adjustable Harmonic Imaging}, volume={10170}, ISBN={["978-1-5106-0825-2"]}, ISSN={["0277-786X"]}, DOI={10.1117/12.2258571}, abstractNote={Acoustic angiography is a contrast-enhanced, superharmonic microvascular imaging method. It has shown the capability of high-resolution and high-contrast-to-tissue-ratio (CTR) imaging for vascular structure near tumor. Dual-frequency ultrasound transducers and arrays are usually used for this new imaging technique. Stacked-type dual-frequency transducers have been developed for this vascular imaging method by exciting injected microbubble contrast agent (MCA) in the vessels with low-frequency (1-5 MHz), moderate power ultrasound burst waves and receiving the superharmonic responses from MCA by a high-frequency receiver (>10 MHz). The main challenge of the conventional dual-frequency transducers is a limited penetration depth (<25 mm) due to the insufficient receiving sensitivity for highfrequency harmonic signal detection. A receiver with a high receiving sensitivity spanning a wide superharmonic frequency range (3rd to 6th) enables selectable bubble harmonic detection considering the required penetration depth. Here, we develop a new dual-frequency transducer composed of a 2 MHz 1-3 composite transmitter and a polyvinylidene fluoride (PVDF) receiver with a receiving frequency range of 4-12 MHz for adjustable harmonic imaging. The developed transducer was tested for harmonic responses from a microbubble-injected vessel-mimicking tube positioned 45 mm away. Despite the long imaging distance (45 mm), the prototype transducer detected clear harmonic response with the contrast-to-noise ratio of 6-20 dB and the -6 dB axial resolution of 200-350 μm for imaging a 200 um-diameter cellulose tube filled with microbubbles.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS 2017}, author={Kim, Jinwook and Lindsey, Brooks D. and Li, Sibo and Dayton, Paul A. and Jiang, Xiaoning}, year={2017} }
 @article{li_duan_semenov_kim_2017, title={Electrical switching of antiferromagnets via strongly spin-orbit coupled materials}, volume={121}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.4974027}, DOI={10.1063/1.4974027}, abstractNote={Electrically controlled ultra-fast switching of an antiferromagnet (AFM) is shown to be realizable by interfacing it with a material of strong spin-orbit coupling. The proximity interaction between the sublattice magnetic moments of a layered AFM and the spin-polarized free electrons at the interface offers an efficient way to manipulate antiferromagnetic states. A quantitative analysis, using the combination with a topological insulator as an example, demonstrates highly reliable 90° and 180° rotations of AFM magnetic states under two different mechanisms of effective torque generation at the interface. The estimated switching speed and energy requirement are in the ps and aJ ranges, respectively, which are about two-three orders of magnitude better than the ferromagnetic counterparts. The observed differences in the magnetization dynamics may explain the disparate characteristic responses. Unlike the usual precessional/chiral motions in the ferromagnets, those of the AFMs can essentially be described as a damped oscillator with a more direct path. The impact of random thermal fluctuations is also examined.}, number={2}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Li, Xi-Lai and Duan, Xiaopeng and Semenov, Yuriy G. and Kim, Ki Wook}, year={2017}, month={Jan}, pages={023907} }
 @article{huang_kim_hou_cann_jones_jiang_2017, title={Flexoelectric characterization of BaTiO3-0.08Bi(Zn1/2Ti1/2)O-3}, volume={110}, number={22}, journal={Applied Physics Letters}, author={Huang, S. J. and Kim, T. and Hou, D. and Cann, D. and Jones, J. L. and Jiang, X. N.}, year={2017} }
 @article{huang_kim_hou_cann_jones_jiang_2017, title={Flexoelectric characterization of BaTiO3-0.08Bi(Zn1/2Ti1/2)O3}, volume={110}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4984212}, DOI={10.1063/1.4984212}, abstractNote={Flexoelectricity, the linear coupling between the strain gradient and the induced electric polarization, has been widely studied as a substitution for piezoelectricity among ceramic lead-free materials. Its potential in micro/nano-scale sensing has especially gained attention, outweighing the performance of cutting edge lead-based piezoelectric materials. In this letter, the flexoelectric coefficient of lead-free ceramic BaTiO3-0.08Bi(Zn1/2Ti1/2)O3 (BT-8BZT) was investigated in the transverse mode. The thermal dependence of flexoelectricity in BT-8BZT was investigated at temperatures ranging from 25 °C to 200 °C, and the results were compared with those of BaxSr1-xTiO3 (BST) ceramics. The effective μ12 of BT-8BZT is ∼25 μC/m at room temperature and can remain as high as ∼13 μC/m at 200 °C. This result suggests that BT-8BZT can be effectively used for micro/nano-sensing within a broad range of temperatures.}, number={22}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Huang, Shujin and Kim, Taeyang and Hou, Dong and Cann, David and Jones, Jacob L. and Jiang, Xiaoning}, year={2017}, month={May}, pages={222904} }
 @article{shu_yong_jiang_xie_huang_2017, title={Flexoelectricity in low densification materials and its implication}, volume={695}, DOI={10.1016/j.jallcom.2016.10.298}, abstractNote={Coupling between the strain gradient and the electric polarization, also named flexoelectricity, is a fundamental but often overlooked property in solid dielectrics. The past ten years has witnessed its great potential in sensing and actuating applications, especially in nanomaterials or nanostructures. The recently discovered giant flexoelectricity in barium strontium titanate (BST) perovskite above its Curie temperature has boosted the research interests on flexoelectricity to a new height. The possible interpretation of the enhanced flexoelectricity in BST was initially attributed to the non-crystalline polar-phases or polar nano-regions existing in the perovskites, then to the inner micro strain generated from the material densification process. In this paper, we analyzed the origin of flexoelectricity in this kind of materials by using both analytical mechanics method and finite element simulation method. Our results suggested the inner micro defect generated during the material densification process would weaken the flexoelectricity of the materials. The observed polarization in the studied materials was likely induced by other mechanisms rather than the pure flexoelectricity.}, journal={Journal of Alloys and Compounds}, author={Shu, L. L. and Yong, Z. H. and Jiang, X. N. and Xie, Z. Q. and Huang, W. B.}, year={2017}, pages={1555–1560} }
 @article{shu_wan_jiang_li_zhou_huang_wang_2017, title={Frequency dispersion of flexoelectricity in PMN-PT single crystal}, volume={7}, ISSN={["2158-3226"]}, DOI={10.1063/1.4973684}, abstractNote={The mechanism of the recent discovered enhanced flexoelectricity in perovskites has brought about numerous controversies which still remain unclear. In this paper, we employed relaxor 0.68Pb(Mg2/3Nb1/3)O3 -0.32PbTiO3 (PMN-PT) single crystals for study. The observed flexoelectric coefficient in PMN-PT single crystal reaches up to 100 μC/m, and in a relative low frequency range, exhibits an abnormal frequency dispersion phenomenon with a positive relationship with frequency. Such frequency dispersion regulation is different from the normal relaxation behavior that usually occur a time delay, and hence proves the flexoelectricity acting more like bulk effect rather than surface effect in this kind of materials.}, number={1}, journal={AIP ADVANCES}, author={Shu, Longlong and Wan, Meiqian and Jiang, Xiaoning and Li, Fei and Zhou, Naigen and Huang, Wenbin and Wang, Tong}, year={2017}, month={Jan} }
 @book{jiang_li_kim_ma_2017, title={High frequency piezo-composite micromachined ultrasound transducer array technology for biomedical imaging}, DOI={10.1115/1.860441}, abstractNote={in this monograph, the authors report the current advancement in high frequency piezoelectric crystal micromachined ultrasound transducers and arrays and their biomedical applications. piezoelectric ultrasound transducers operating at high frequencies (>20 mhz) are of increasing demand in recent years for medical imaging and biological particle manipulation involved therapy. The performances of transducers greatly rely on the properties of the piezoelectric materials and transduction structures, including piezoelectric coefficient (d), electromechanical coupling coefficient (k), dielectric permittivity (e) and acoustic impedance (Z). piezo-composite structures are preferred because of their relatively high electromechanical coupling coefficient and low acoustic impedance. a number of piezo-composite techniques have been developed, namely “dice and fill”, “tape-casting”, “stack and bond”, “interdigital phase bonding”, “laser micromachining” and “micro-molding”. however, these techniques are either difficult to achieve fine features or not suitable for manufacturing of high frequency ultrasound transducers (>20 mhz). The piezo-composite micromachined ultrasound transducers (pc-mUT) technique discovered over the last 10 years or so has demonstrated high performance high frequency piezo-composite ultrasound transducers. in this monograph, piezoelectric materials used for high frequency transducers is introduced first. Next, the benefits and theory of piezo composites is presented, followed by the design criteria and fabrication methods. Biomedical applications using pc-mUT and arrays will also be reported, in comparison with other ultrasound transducer techniques. The final part of this monograph describes challenges and future perspectives of this technique for biomedical applications. ASME_Bionano Monograph Jiang_FM.indd vi Manila Typesetting Company 08/29/2017 09:58PM ASME_Bionano Monograph Jiang_FM.indd vii Manila Typesetting Company 08/29/2017 09:58PM Downloaded From: http://asmedigitalcollection.asme.org on 10/21/2018 Terms of Use: http://www.asme.org/about-asme/terms-of-use Downloaded From: http://asmedigitalcollection.asme.org on 10/21/2018 Terms of Use: http://www.asme.org/about-asme/terms-of-use}, publisher={New York, NY, USA: ASME Press}, author={Jiang, X. and Li, S. and Kim, J. and Ma, J.}, year={2017} }
 @article{kim_kim_jiang_2017, title={High temperature transducer using aluminum nitride single crystal for laser ultrasound detection}, volume={10169}, ISBN={["978-1-5106-0824-5"]}, ISSN={["0277-786X"]}, DOI={10.1117/12.2259975}, abstractNote={In this work, a new ultrasound nondestructive testing (NDT) method based on laser-generated Lamb wave detection was proposed for high temperature (HT) NDT. Lamb waves were introduced to a stainless steel plate by the Nd:YAG pulsed laser at one point and detected by aluminum nitride (AlN) transducer at a distant position. The fundamental symmetric (S0) and antisymmetric (A0) mode Lamb waves were successfully propagated in the thin stainless steel plate. The time-of- flight (TOF) of the S0 and A0 mode waves proportionally increased with the distance (D) between the laser source and the sensor, and almost no attenuation of the amplitude was observed. For the HT NDT experiment, AlN single crystal was adopted as the ultrasonic sensor material due to its high thermal resistance of the dielectric and piezoelectric constants at the elevated temperature up to 800 °C. The combination of non-contact, portable laser source as a Lamb wave generator and temperature-robust NDT sensor made of AIN has shown its great capability to detect the Lamb waves at elevated temperatures.}, journal={NONDESTRUCTIVE CHARACTERIZATION AND MONITORING OF ADVANCED MATERIALS, AEROSPACE, AND CIVIL INFRASTRUCTURE 2017}, author={Kim, Taeyang and Kim, Jinwook and Jiang, Xiaoning}, year={2017} }
 @article{kim_lindsey_chang_dai_stavas_dayton_jiang_2017, title={Intravascular forward-looking ultrasound transducers for microbubble-mediated sonothrombolysis}, volume={7}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-017-03492-4}, abstractNote={Abstract}, journal={SCIENTIFIC REPORTS}, author={Kim, Jinwook and Lindsey, Brooks D. and Chang, Wei-Yi and Dai, Xuming and Stavas, Joseph M. and Dayton, Paul A. and Jiang, Xiaoning}, year={2017}, month={Jun} }
 @article{suo_jin_jiang_dayton_jing_2017, title={Microbubble mediated dual-frequency high intensity focused ultrasound thrombolysis: An In vitro study}, volume={110}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4973857}, DOI={10.1063/1.4973857}, abstractNote={High intensity focused ultrasound (HIFU) has recently emerged as a promising alternative approach for thrombolysis. However, the high acoustic energy required by HIFU could elicit thermal damage bioeffects, impeding the clinical translation of this technique. This paper investigates the use of dual-frequency focused ultrasound (DFFU) mediated by microbubbles (MBs) to minimize the acoustic power required for thrombolysis in vitro. It was found that MBs, with sufficient concentration, could significantly lower the power threshold for thrombolysis for both DFFU and single-frequency focused ultrasound (SFFU). In addition, SFFU needs about 96%–156% higher energy to achieve the same thrombolysis efficiency as that of DFFU. The thrombolysis efficiency is also found to increase with the duty cycle. The measured cavitation signals reveal that the enhanced inertial cavitation is likely responsible for the improved thrombolysis under DFFU and MBs.}, number={2}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Suo, Dingjie and Jin, Zhiyang and Jiang, Xiaoning and Dayton, Paul A. and Jing, Yun}, year={2017}, month={Jan}, pages={023703} }
 @inproceedings{chang_zhang_kim_huang_chang_jiang_2017, title={Photoacoustic transduction efficiency evaluation of candle soot nanoparticles/PDMS composites}, DOI={10.1109/nano.2017.8117338}, abstractNote={Carbon-based materials have been considered as an efficient light-absorption component of film-type laser ultrasound transducers. Our previously designed laser ultrasound patch composed of candle soot nanoparticles and polydimethylsiloxane (CS/PDMS) composites showed high photoacoustic transducer efficiency than other carbon-based composites. In this study, we demonstrate that the carbon volume fraction and the thickness of clustered carbon nanoparticles of CS/PDMS composites are highly related to the photoacoustic transduction efficiency. This study builds upon our previous study to characterize optical properties of the CS/PDMS composites in both experimental measurements and finite difference time domain (FDTD) analysis in the visible wavelength range.}, booktitle={2017 ieee 17th international conference on nanotechnology (ieee-nano)}, author={Chang, W. Y. and Zhang, X. A. and Kim, J. and Huang, W. B. and Chang, C. H. and Jiang, X. N.}, year={2017}, pages={439–442} }
 @article{kim_saini_kim_gopalarathnam_zhu_palmieri_wohl_jiang_2017, title={Piezoelectric Floating Element Shear Stress Sensor for the Wind Tunnel Flow Measurement}, volume={64}, ISSN={["1557-9948"]}, DOI={10.1109/tie.2016.2630670}, abstractNote={A piezoelectric (PE) sensor with a floating element was developed for direct measurement of flow induced shear stress. The PE sensor was designed to detect the pure shear stress while suppressing the effect of normal stress generated from the vortex lift up by applying opposite poling vectors to the PE elements. During the calibration stage, the prototyped sensor showed a high sensitivity to shear stress (91.3 ± 2.1 pC/Pa) due to the high PE coefficients (<inline-formula><tex-math notation="LaTeX">$d_{{31}}=- $</tex-math></inline-formula>1330 pC/N) of the constituent 0.67Pb(Mg<inline-formula><tex-math notation="LaTeX">$_{1/3} $</tex-math></inline-formula>Nb<inline-formula> <tex-math notation="LaTeX">$_{2/3} $</tex-math></inline-formula>)O<sub>3</sub>–0.33PbTiO<sub>3</sub> (PMN–33%PT) single crystal. By contrast, the sensor showed almost no sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the sensing structure. The usable frequency range of the sensor is up to 800 Hz. In subsonic wind tunnel tests, an analytical model was proposed based on cantilever beam theory with an end-tip-mass for verifying the resonance frequency shift in static stress measurements. For dynamic stress measurements, the signal-to-noise ratio (SNR) and ambient vibration-filtered pure shear stress sensitivity were obtained through signal processing. The developed PE shear stress sensor was found to have an SNR of 15.8 ± 2.2 dB and a sensitivity of 56.5 ± 4.6 pC/Pa in the turbulent flow.}, number={9}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Kim, Taeyang and Saini, Aditya and Kim, Jinwook and Gopalarathnam, Ashok and Zhu, Yong and Palmieri, Frank L. and Wohl, Christopher J. and Jiang, Xiaoning}, year={2017}, month={Sep}, pages={7304–7312} }
 @article{berik_chang_jiang_2017, title={Piezoelectric d(36) in-plane shear-mode of lead-free BZT-BCT single crystals for torsion actuation}, volume={110}, ISSN={["1077-3118"]}, DOI={10.1063/1.4975587}, abstractNote={We report the study of piezoelectric direct torsion actuation mechanism using lead-free piezoelectric d36 in-plane shear-mode BZT-BCT single crystals. The generated angle of twist of the piezoelectric torsion actuator was obtained from the transverse deflection measurement using a laser vibrometer. The bi-morph torsional actuator, consisting of two lead-free piezoelectric BZT-BCT in-plane shear-mode single crystals with a giant piezoelectric d36 shear strain coefficient of 1590 pC/N, provided a rate of twist of 34.12 mm/m under a quasi-static 15 V drive. The experimental benchmark was further modelled and verified by the ANSYS software using three dimensional (3D) piezoelectric finite elements. The experimental results revealed that lead-free piezoelectric BZT-BCT d36-mode single crystal is a superior candidate for piezoelectric torsion actuation. This lead-free piezoelectric BZT-BCT d36-mode torsion actuator can be effectively applied in torsional deformation control by taking into account the environmental considerations.}, number={5}, journal={APPLIED PHYSICS LETTERS}, author={Berik, P. and Chang, W. -Y. and Jiang, X.}, year={2017}, month={Jan} }
 @article{sang_yuan_zheng_sun_qi_zhang_jiang_li_du_2017, title={Raman spectra of (K, Na)(Nb,Ta)O-3 single crystal}, volume={704}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2016.12.166}, abstractNote={The Raman scattering spectra for lead-free piezoelectric single crystal (K,Na)(Nb,Ta)O3 (KNNT) were intensively investigated to explore its crystallographic structure. For the [011]C oriented sample, 12 Raman peaks were identified from the room temperature Raman spectrum. The υ3, υ4 and υ6 modes which should be Raman silent in normal perovskites were observed due to the low symmetry (Pm) of KNNT single crystal. The temperature dependent Raman spectra indicated that the orthorhombic-tetragonal phase transition happened at about 68 °C, and the Curie temperature (TC) is about 225 °C. The merging of 2 υ5 modes at TC was ascribed to the vanishing of polarization. The backscattering polarized Raman spectra of KNNT single crystals with different orientations were analyzed. The Raman modes were identified using polarized selection rules based on group theory.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Sang, Shijing and Yuan, Zhongyuan and Zheng, Limei and Sun, Enwei and Qi, Xudong and Zhang, Rui and Jiang, Xiaoning and Li, Shiyang and Du, Juan}, year={2017}, month={May}, pages={804–808} }
 @article{kim_kim_jiang_2017, title={Transit Time Difference Flowmeter for Intravenous Flow Rate Measurement Using 1-3 Piezoelectric Composite Transducers}, volume={17}, ISSN={["1558-1748"]}, DOI={10.1109/jsen.2017.2727340}, abstractNote={The flow rate of injected medication implemented by intravenous (IV) systems must be accurately monitored and meticulously controlled to prevent medical accidents. In this paper, an ultrasonic flowmeter (UF) with 1–3 piezoelectric composite transducers was designed, fabricated, and tested on a variety of flow rates of mimic medical injections. The transducer wedge for the angled beam propagation and an acoustic impedance matching layer were included in the design for transmission enhancement. To ensure an accurate measurement of flow rate, the effect of the flow distributions inside the IV tube was taken into account. The developed UF exhibited the capability of detecting low flow rates (<0.005 m/s), with 1%–2% discrepancy compared with the reference rate of infusion.}, number={17}, journal={IEEE SENSORS JOURNAL}, author={Kim, Taeyang and Kim, Jinwook and Jiang, Xiaoning}, year={2017}, month={Sep}, pages={5741–5748} }
 @inproceedings{li_huang_chang_jiang_2016, title={40-MHz micromachined PMN-PT composite ultrasound array for medical imaging}, DOI={10.1115/imece2015-52540}, abstractNote={Ultrasonography is well known as a relatively low cost and non-invasive modality for real-time imaging. In recent years, various high frequency array transducers have been developed and used for ophthalmology, dermatology, and small animal studies. This paper reports the development of a 48-element 40-MHz ultrasonic array using micromachined lead magnesium niobate-lead titanate (PMN-PT) single crystal 1–3 composite material. Array elements with a pitch of 100-micron were interconnected via a customized flexible circuit. Pulse-echo test showed an average center frequency of 40 MHz and a −6 dB fractional bandwidth of 52%. The −20 dB pulse length was evaluated as 120 ns. The electrical and acoustical separation showed the crosstalk less than - 24 dB. An image of a steel wire target phantom was acquired by stacking multiple A-lines. The results demonstrate resolutions exceeding 70 μm axially and 800 μm laterally. Those results imply the great potential of the developed array transducer for the high frequency medical imaging.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2015, vol 3}, author={Li, S. B. and Huang, W. B. and Chang, W. Y. and Jiang, X. N.}, year={2016} }
 @article{huang_chang_kim_li_huang_jiang_2016, title={A Novel Laser Ultrasound Transducer Using Candle Soot Carbon Nanoparticles}, volume={15}, ISSN={["1941-0085"]}, DOI={10.1109/tnano.2016.2536739}, abstractNote={As a novel composite material for laser ultrasound transducer, candle soot nanoparticles polydimethylsiloxane (CSPs-PDMS) has been demonstrated to generate high frequency, broadband, and high-amplitude ultrasound waves. In this study, we investigated the mechanism of the high-optoacoustic conversion efficiency exhibited by the composite. A thermal-acoustic coupling model was proposed for analyzing the performance of the composite. The theoretical result matches well with the experimental observation. The acoustic beam profile was compared with Field II simulation results. The 4.41 × 10-3 energy conversion coefficient and 21 MHz--6 dB frequency bandwidth of the composite suggest that CSPs-PDMS composites is promising for a broad range of ultrasound therapy and non-destructive testing applications.}, number={3}, journal={IEEE TRANSACTIONS ON NANOTECHNOLOGY}, author={Huang, Wenbin and Chang, Wei-Yi and Kim, Jinwook and Li, Sibo and Huang, Shujin and Jiang, Xiaoning}, year={2016}, month={May}, pages={395–401} }
 @article{huang_kim_kim_bakshi_williams_matthieu_loboa_shung_zhou_jiang_2016, title={A Novel Ultrasound Technique for Non-Invasive Assessment of Cell Differentiation}, volume={16}, ISSN={["1558-1748"]}, DOI={10.1109/jsen.2015.2477340}, abstractNote={A novel technique for the characterization of mammalian cells during cell culture was studied using a lead magnesium niobate-lead titanate single crystal piezoelectric resonator. Tests were conducted to observe changes in material properties of human adipose derived stem cells during both proliferation and osteogenic differentiation. The resonator electrical impedance was recorded as a function of the cell acoustic impedance, an indicator of cell viscoelasticity. Observed electrical impedance change (in percentage) from day 1 to day 14 for human adipose derived stem cells undergoing chemical-induced osteogenic differentiation was ~1.7× that observed for proliferating stem cells maintained in complete growth medium.}, number={1}, journal={IEEE SENSORS JOURNAL}, author={Huang, Wenbin and Kim, Jinwook and Kim, Kyngrim and Bakshi, Saurabh and Williams, John and Matthieu, Pattie and Loboa, Elizabeth and Shung, Koping Kirk and Zhou, Qifa and Jiang, Xiaoning}, year={2016}, month={Jan}, pages={61–68} }
 @inproceedings{wang_martin_dayton_jiang_2016, title={A dual frequency ivus transducer with a lateral mode transmitter for contrast enhanced intravascular ultrasound imaging}, DOI={10.1115/imece2015-51131}, abstractNote={Recent studies suggest that dual frequency intravascular ultrasound (IVUS) transducers are promising in contrast ultrasound for molecular imaging or vasa vasorum (VV) assessment to identify vulnerable plaques. Low frequency (1–3 MHz) acoustic waves are widely used for contrast imaging because it can excite microbubbles more effectively. However, conventional thickness mode 1–3 MHz transducers are not suitable for IVUS since bulky transducer size is not permitted in fine IVUS catheters used for coronary interventions (approx. 3-French). In this paper, a dual frequency (2.25 MHz/30 MHz) IVUS transducer with a lateral mode transmitter (2.25 MHz) and a thickness mode high frequency receiver (30 MHz) was designed, fabricated and characterized. In contrast detection tests, superharmonic microbubble responses flown through a 200 μm diameter tube was successfully detected with a contrast to noise ratio (CNR) of 13 dB and an axial resolution (−6 dB) of 0.1 μs (150 μm). The results showed that this dual frequency IVUS transducer with a lateral mode transmitter can be used to detect super-harmonic signal (12th to 15th harmonic) ideal for superharmonic imaging of microvascular structures.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2015, vol 3}, author={Wang, Z. C. and Martin, K. H. and Dayton, P. A. and Jiang, X. N.}, year={2016} }
 @inproceedings{li_kim_wang_jiang_kasoji_lindsey_dayton_2016, title={A dual-frequency co-linear array for prostate acoustic angiography}, DOI={10.1109/ultsym.2016.7728718}, abstractNote={Approximately 80% of men who reach 80-years of age will have some form of prostate cancer. The challenge remains to differentiate indolent from aggressive disease. Based on recent research, acoustic angiography, a novel contrast enhanced ultrasound imaging technique, can provide high-resolution visualization of tissue microvasculature and has demonstrated the ability to differentiate vascular characteristics between healthy and tumor tissue. We hypothesize that transrectal acoustic angiography may enhance assessment of prostate cancer. In this paper, we describe the development of a dual layer co-linear array ultrasound transducer for transrectal acoustic angiography. The KLM model and Field II were used for the element design and acoustic field simulation, respectively. The probe consists of 64 transmit elements with a center frequency of 3 MHz and 128 receive elements with a center frequency of 15 MHz. The dimensions of the array are 18 mm in azimuth and 8 mm in elevation. The pitch is 280 μm for transmitting (TX) elements and 140 μm for receiving (RX) elements. Pulse-echo test of TX/RX elements were conducted and compared with the simulation results. Real-time contrast imaging was tested using a Verasonics system. Non-linear responses from microbubble contrast agents at a depth of 18 mm were clearly observed. The axial beam width (-6 dB) and CTR were calculated from the measured signals to be 400 μm and 20 dB, respectively. These results suggest that the prototype co-linear array is capable of performing dual-frequency superharmonic imaging of microbubbles for prostate cancer assessment.}, booktitle={2016 ieee international ultrasonics symposium (ius)}, author={Li, S. B. and Kim, J. and Wang, Z. C. and Jiang, X. N. and Kasoji, S. and Lindsey, B. and Dayton, P. A.}, year={2016} }
 @inproceedings{lindsey_dayton_kim_jiang_2016, title={A dual-frequency endoscopic transducer for imaging vascular invasion in pancreatic cancer}, DOI={10.1109/ultsym.2016.7728435}, abstractNote={Pancreatic adenocarcinoma is among the most deadly of cancers, with surgery being typically the only curative option. Tumor resectability is typically determined via endoscopic ultrasound imaging, however, many patients who may be eligible for resection are not offered surgery due to the difficulty in determining vascular or lymphatic invasion. Contrast-enhanced ultrasound imaging may address this problem. We describe the development of a single element dual-frequency transducer for rotational endoscopic imaging designed to operate at 4/20 MHz to image microbubble superharmonics. The ability of the developed transducer to image in a tissue mimicking phantom at depths from 1.0 cm (CTR = 21.6 dB) to 2.5 cm (CTR = 11.4 dB) is demonstrated. The completed 4-Fr transducer is also capable of imaging microbubbles in a 200 μm-diameter tube through the wall of a ~1 cm-diameter porcine artery, suggesting such a device may be suitable for direct visualization of small vessels from within the lumen of larger vessels such as the portal vein.}, booktitle={2016 ieee international ultrasonics symposium (ius)}, author={Lindsey, B. D. and Dayton, P. A. and Kim, J. and Jiang, X. N.}, year={2016} }
 @article{kim_saini_kim_gopalarathnam_zhu_palmieri_wohl_jiang_2016, title={A piezoelectric shear stress sensor}, volume={9803}, ISSN={["1996-756X"]}, DOI={10.1117/12.2219185}, abstractNote={In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress, suppressing effects of normal stress components, by applying opposite poling vectors to the piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces where it demonstrated high sensitivity to shear stress (91.3 ± 2.1 pC/Pa) due to the high piezoelectric coefficients of 0.67Pb(Mg1∕3Nb2∕3)O3-0.33PbTiO3 (PMN-33%PT, d31=-1330 pC/N). The sensor also exhibited negligible sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is up to 800 Hz.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2016}, author={Kim, Taeyang and Saini, Aditya and Kim, Jinwook and Gopalarathnam, Ashok and Zhu, Yong and Palmieri, Frank L. and Wohl, Christopher J. and Jiang, Xiaoning}, year={2016} }
 @article{lindsey_martin_jiang_dayton_2016, title={Adaptive windowing in contrast-enhanced intravascular ultrasound imaging}, volume={70}, ISSN={["1874-9968"]}, DOI={10.1016/j.ultras.2016.04.022}, abstractNote={Intravascular ultrasound (IVUS) is one of the most commonly-used interventional imaging techniques and has seen recent innovations which attempt to characterize the risk posed by atherosclerotic plaques. One such development is the use of microbubble contrast agents to image vasa vasorum, fine vessels which supply oxygen and nutrients to the walls of coronary arteries and typically have diameters less than 200μm. The degree of vasa vasorum neovascularization within plaques is positively correlated with plaque vulnerability. Having recently presented a prototype dual-frequency transducer for contrast agent-specific intravascular imaging, here we describe signal processing approaches based on minimum variance (MV) beamforming and the phase coherence factor (PCF) for improving the spatial resolution and contrast-to-tissue ratio (CTR) in IVUS imaging. These approaches are examined through simulations, phantom studies, ex vivo studies in porcine arteries, and in vivo studies in chicken embryos. In phantom studies, PCF processing improved CTR by a mean of 4.2dB, while combined MV and PCF processing improved spatial resolution by 41.7%. Improvements of 2.2dB in CTR and 37.2% in resolution were observed in vivo. Applying these processing strategies can enhance image quality in conventional B-mode IVUS or in contrast-enhanced IVUS, where signal-to-noise ratio is relatively low and resolution is at a premium.}, journal={ULTRASONICS}, author={Lindsey, Brooks D. and Martin, K. Heath and Jiang, Xiaoning and Dayton, Paul A.}, year={2016}, month={Aug}, pages={123–135} }
 @inproceedings{lindsey_dayton_jiang_2016, title={Adaptive windowing in mechanically-steered intravascular ultrasound imaging: Ex vivo and in vivo studies with contrast enhancement}, DOI={10.1109/ultsym.2016.7728433}, abstractNote={Intravascular ultrasound (IVUS) is utilized frequently in vascular diseases such as coronary artery disease and peripheral vascular disease. Many techniques-including but not limited to IVUS-seek to characterize plaques in coronary artery disease in order to determine which are likely to rupture. Biologists have recently identified the development of intra-plaque vasa vasorum, small vessels which supply the coronaries with oxygen and nutrients, as a potential indicator of plaque vulnerability. By imaging plaques with penetrating vasa vasorum, high resolution contrast-enhanced ultrasound imaging may allow identification of vulnerable plaques prior to rupture. Here we present processing techniques for improving spatial resolution and image contrast in mechanically steered ultrasound imaging based on minimum variance (MV) beamforming and the phase coherence factor (PCF). In tissue-mimicking phantom studies, PCF processing improved CTR by a mean of 4.2 dB, while combined MV and PCF processing improved spatial resolution by 41.7%. These processing strategies may improve image quality in both conventional B-mode IVUS and contrast-enhanced IVUS.}, booktitle={2016 ieee international ultrasonics symposium (ius)}, author={Lindsey, B. D. and Dayton, P. A. and Jiang, X. N.}, year={2016} }
 @article{li_ma_martin_yu_ma_dayton_jiang_shung_zhou_2016, title={An Integrated System for Superharmonic Contrast-Enhanced Ultrasound Imaging: Design and Intravascular Phantom Imaging Study}, volume={63}, ISSN={["1558-2531"]}, DOI={10.1109/tbme.2015.2506639}, abstractNote={Objective: Superharmonic contrast-enhanced ultrasound imaging, also called acoustic angiography, has previously been used for the imaging of microvasculature. This approach excites microbubble contrast agents near their resonance frequency and receives echoes at nonoverlapping superharmonic bandwidths. No integrated system currently exists could fully support this application. To fulfill this need, an integrated dual-channel transmit/receive system for superharmonic imaging was designed, built, and characterized experimentally. Method: The system was uniquely designed for superharmonic imaging and high-resolution B-mode imaging. A complete ultrasound system including a pulse generator, a data acquisition unit, and a signal processing unit were integrated into a single package. The system was controlled by a field-programmable gate array, on which multiple user-defined modes were implemented. A 6-, 35-MHz dual-frequency dual-element intravascular ultrasound transducer was designed and used for imaging. Result: The system successfully obtained high-resolution B-mode images of coronary artery ex vivo with 45-dB dynamic range. The system was capable of acquiring in vitro superharmonic images of a vasa vasorum mimicking phantom with 30-dB contrast. It could detect a contrast agent filled tissue mimicking tube of 200 μm diameter. Conclusion: For the first time, high-resolution B-mode images and superharmonic images were obtained in an intravascular phantom, made possible by the dedicated integrated system proposed. The system greatly reduced the cost and complexity of the superharmonic imaging intended for preclinical study. Significant: The system showed promise for high-contrast intravascular microvascular imaging, which may have significant importance in assessment of the vasa vasorum associated with atherosclerotic plaques.}, number={9}, journal={IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING}, author={Li, Yang and Ma, Jianguo and Martin, K. Heath and Yu, Mingyue and Ma, Teng and Dayton, Paul A. and Jiang, Xiaoning and Shung, K. Kirk and Zhou, Qifa}, year={2016}, month={Sep}, pages={1933–1943} }
 @article{shi_huang_li_li_xu_jiang_wei_2016, title={Analysis on the anisotropic electromechanical properties of lead magnoniobate titanate single crystal for ring type ultrasonic motors}, volume={6}, ISSN={["2158-3226"]}, DOI={10.1063/1.4967823}, abstractNote={This work discussed the optimized cut of single crystal lead magnoniobate titanate (PMNT) for use of ring type travelling wave ultrasonic motors (USMs), according to anisotropic analysis on electromechanical properties. The selection criterion of crystal orientation relies on the circular uniformity of the induced travelling wave amplitude on the stator surface. By calculating the equivalent elastic coefficient c11 and lateral piezoelectric constant d31, the optimal crystal orientations were proposed for PMNT single crystals poled along different directions. For single crystal poled along <001>c directions, the optimal orientation lies along [001]c with d31=-1335pC/N and k31=0.87. The crystallographic orientation [025]c is the optimized orientation for single crystals poled along <011>c direction with d31=199pC/N and k31=0.55. The optimal orientation of 1R configuration is [332¯]c with a large enhancement of d31 = 1201 and k31=0.92.}, number={11}, journal={AIP ADVANCES}, author={Shi, Xiang and Huang, Wenbin and Li, Fei and Li, Zhenrong and Xu, Zhuo and Jiang, Xiaoning and Wei, Xiaoyong}, year={2016}, month={Nov} }
 @article{wang_li_czernuszewicz_gallippi_liu_geng_jiang_2016, title={Design, Fabrication, and Characterization of a Bifrequency Colinear Array}, volume={63}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2015.2506000}, abstractNote={Ultrasound imaging with high resolution and large penetration depth has been increasingly adopted in medical diagnosis, surgery guidance, and treatment assessment. Conventional ultrasound works at a particular frequency, with a - 6-dB fractional bandwidth of ~ 70% , limiting the imaging resolution or depth of field. In this paper, a bifrequency colinear array with resonant frequencies of 8 and 20 MHz was investigated to meet the requirements of resolution and penetration depth for a broad range of ultrasound imaging applications. Specifically, a 32-element bifrequency colinear array was designed and fabricated, followed by element characterization and real-time sectorial scan (S-scan) phantom imaging using a Verasonics system. The bifrequency colinear array was tested in four different modes by switching between low and high frequencies on transmit and receive. The four modes included the following: 1) transmit low, receive low; 2) transmit low, receive high; 3) transmit high, receive low; and 4) transmit high, receive high. After testing, the axial and lateral resolutions of all modes were calculated and compared. The results of this study suggest that bifrequency colinear arrays are potential aids for wideband fundamental imaging and harmonic/subharmonic imaging.}, number={2}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Wang, Zhuochen and Li, Sibo and Czernuszewicz, Tomasz J. and Gallippi, Caterina M. and Liu, Ruibin and Geng, Xuecang and Jiang, Xiaoning}, year={2016}, month={Feb}, pages={266–274} }
 @article{martin_lindsey_ma_nichols_jiang_dayton_2016, title={EX VIVO PORCINE ARTERIAL AND CHORIOALLANTOIC MEMBRANE ACOUSTIC ANGIOGRAPHY USING DUAL-FREQUENCY INTRAVASCULAR ULTRASOUND PROBES}, volume={42}, ISSN={["1879-291X"]}, DOI={10.1016/j.ultrasmedbio.2016.04.008}, abstractNote={The presence of blood vessels within a developing atherosclerotic plaque has been found to be correlated with increased plaque vulnerability and ensuing cardiac events, however, detection of coronary intraplaque neovascularization poses a significant challenge in the clinic. We describe here a new in vivo intravascular ultrasound imaging method using a dual-frequency transducer to visualize contrast flow in microvessels with high specificity. This method uses a specialized transducer capable of exciting contrast agents at a low frequency (5.5 MHz) while detecting their nonlinear superhamonics at a much higher frequency (37 MHz). In vitro evaluation of the approach was performed in a microvascular phantom to produce 3-D renderings of simulated vessel patterns and to determine image quality metrics as a function of depth. Furthermore, we describe the ability of the system to detect microvessels both ex vivo using porcine arteries and in vivo using the chorioallantoic membrane of a developing chicken embryo with optical confirmation. Dual-frequency contrast-specific imaging was able to resolve vessels similar in size to those found in vulnerable atherosclerotic plaques at clinically relevant depths. The results of this study add to the support for further evaluation and translation of contrast-specific imaging in intravascular ultrasound for the detection of vulnerable plaques in atherosclerosis.}, number={9}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Martin, K. Heath and Lindsey, Brooks D. and Ma, Jianguo and Nichols, Timothy C. and Jiang, Xiaoning and Dayton, Paul A.}, year={2016}, month={Sep}, pages={2294–2307} }
 @inproceedings{kim_chang_lindsey_dayton_dai_stavas_jiang_2016, title={Laser-generated-focused ultrasound transducers for microbubble-mediated, dual-excitation sonothrombolysis}, DOI={10.1109/ultsym.2016.7728473}, abstractNote={A laser-generated-focused ultrasound (LGFU) transducer generates high-pressure (up to 20 MPa), high-frequency (>10 MHz) shock waves with a tight focal spot. In this work, we aim to demonstrate the feasibility of using LGFU transducers for sonothrombolysis in vitro. A carbon black LGFU transducer was designed, fabricated and characterized. The prototyped LGFU was applied with in-vitro thrombolysis tests involving microbubble contrast agent (MCA). A conventional piezo ultrasound transducer was used as a secondary excitation source to enhance the cavitation effect by dual-frequency excitation. The in vitro test results showed that microbubble-mediated LGFU treatment can yield the lytic rate of approximately 2 mg/min, suggesting that LGFU transducers may be useful in precision high lytic rate sonothrombolysis.}, booktitle={2016 ieee international ultrasonics symposium (ius)}, author={Kim, J. and Chang, W. Y. and Lindsey, B. D. and Dayton, P. A. and Dai, X. M. and Stavas, J. M. and Jiang, X. N.}, year={2016} }
 @inproceedings{an_wang_li_jiang_2016, title={Modeling of harmonic measurement radiated by a plane circular piston in fluids}, DOI={10.1109/spawda.2016.7830007}, abstractNote={In recent years, the use of nonlinear ultrasound in medical and industrial applications has increased rapidly. Harmonic signals, generated from nonlinear distortion of ultrasonic wave propagation in fluid or solid media, play an important role not only in ultrasonic medical imaging to provide higher resolution and higher contrast to tissue ratio, but also in nondestructive testing of fatigue cracks to provide higher sensitivity. We present a finite element model that embodies all the factors (diffraction, attenuation, receiver integration and tone-burst excitation) mentioned previously to describe the nonlinear characteristics of the ultrasonic field radiated by a plane circular piston source in fluids more accurately. A computer controlled ultrasonic system (RAM-5000 SNAP, Ritec Inc.) was used to verify the numerical predictions. The fundamental and the second harmonic versus axial distance are compared, and a reasonable agreement is achieved.}, booktitle={Proceedings of 2016 Symposium on Piezoelectricity, Acoustic Waves, and Device Applications (SPAWDA)}, author={An, Z. W. and Wang, Z. C. and Li, H. Y. and Jiang, X. N.}, year={2016}, pages={288–292} }
 @inproceedings{kim_chang_huang_jiang_2016, title={Nanocomposite transducer with a laser ultarsound transmitter and a piezoelectric receiver}, DOI={10.1109/nano.2016.7751440}, abstractNote={Laser ultrasound transducers, converting the laser pulses into acoustic waves with high frequency, broadband and high pressure amplitude, is attractive to many biomedical and industrial applications. In this paper, nanocomposites consisting of carbon nanomaterials, PDMS and PVDF were incorporated into a transducer structure for ultrasound transmitting and receiving. The prototyped nanocomposite transducers were characterized by conducting pulse-echo tests. The obtained center frequency is 12 MHz, -6 dB fractional bandwidth is 138%, and the signal-to-noise ratio of 42 dB with an excitation of ~5 mJ of 532 nm, 6 ns pulsed laser. These initial findings strongly suggest that laser ultrasound transducers are promising for advanced ultrasound imaging applications.}, booktitle={2016 IEEE 16th International Conference on Nanotechnology (IEEE-nano)}, author={Kim, J. and Chang, W. Y. and Huang, S. J. and Jiang, X. N.}, year={2016}, pages={191–192} }
 @article{kwon_huang_zhang_yuan_jiang_2016, title={Study on a flexoelectric microphone using barium strontium titanate}, volume={26}, ISSN={["1361-6439"]}, DOI={10.1088/0960-1317/26/4/045001}, abstractNote={In this study, a flexoelectric microphone was, for the first time, designed and fabricated in a bridge structure using barium strontium titanate (Ba0.65Sr0.35TiO3) ceramic and tested afterwards. The prototyped flexoelectric microphone consists of a 1.5 mm  ×  768 μm  ×  50 μm BST bridge structure and a silicon substrate with a cavity. The sensitivity and resonance frequency were designed to be 0.92 pC/Pa and 98.67 kHz, respectively. The signal to noise ratio was measured to be 74 dB. The results demonstrate that the flexoelectric microphone possesses high sensitivity and a wide working frequency range simultaneously, suggesting that flexoelectricity could be an excellent alternative sensing mechanism for microphone applications.}, number={4}, journal={JOURNAL OF MICROMECHANICS AND MICROENGINEERING}, author={Kwon, S. R. and Huang, W. B. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N.}, year={2016}, month={Apr} }
 @article{kim_huang_huang_jiang_2016, title={Thermal gradient induced flexoelectric effects in bulk Ba0.67Sr0.33TiO3}, volume={108}, ISSN={["1077-3118"]}, DOI={10.1063/1.4949358}, abstractNote={Flexoelectric effect, denoting electric field gradient induced mechanical strain or mechanical strain gradient induced electric polarization, is a universal phenomenon in all dielectrics. Although research on the topic of flexoelectricity under stress fields and electric fields has advanced significantly, information regarding the phenomenon under thermal fields is rather limited. In this letter, the flexoelectricity field of Ba0.67Sr0.33TiO3 (BST) was investigated by generating temperature gradients along the lengths of samples with symmetric geometry. An electric field gradient induced by a thermal gradient was analyzed based on the temperature-dependent dielectric property of BST. The strain was then experimentally verified due to the electric field gradient. Experimental results suggest converse flexoelectric effect of BST samples with symmetric geometry in a thermal field. This result was not only consistent with the theoretical prediction, but it also followed the scaling effect of flexoelectricity.}, number={19}, journal={APPLIED PHYSICS LETTERS}, author={Kim, Taeyang and Huang, Wenbin and Huang, Shujin and Jiang, Xiaoning}, year={2016}, month={May} }
 @article{shu_wang_jiang_huang_2016, title={Verification of the flexoelectricity in barium strontium titanate through d33 meter}, volume={6}, ISSN={2158-3226}, url={http://dx.doi.org/10.1063/1.4968524}, DOI={10.1063/1.4968524}, abstractNote={Flexoelectricity is a newly arising electromechanical property that couples strain gradient to polarization. This physical property widely exists in most of the solid dielectrics but has quite weak response that often overlooked. Recently, barium strontium titanate (BST), a well-known ferroelectrics, has been reported to be a promising flexoelectric material, and thus triggered the associated studies on flexoelectricity to a new height. However, part of the researchers argued the observed flexoelectricity in BST is either by residual piezoelectricity or centric symmetry breaking during the densification process. In this paper, we would verify the flexoelectricity in BST ceramics by many comparison experiments. Our experimental result suggested the observed polarization in BST material is likely to be induced by strain gradient through flexoelectricity.}, number={12}, journal={AIP Advances}, publisher={AIP Publishing}, author={Shu, Longlong and Wang, Tong and Jiang, Xiaoning and Huang, Wenbin}, year={2016}, month={Dec}, pages={125003} }
 @article{li_kim_wang_jiang_kasoji_lindsey_dayton_2015, title={A 3 MHz/18 MHz Dual-layer Co-Linear Array for Transrectal Acoustic Angiography}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0030}, abstractNote={In this paper, a novel dual layer co-linear array ultrasound transducer was developed for transrectal dual-frequency superharmonic imaging. The KLM model and Field II were used for the acoustic stack design and simulation of the acoustic field of the array, respectively. The newly designed and fabricated probe consists of 50 transmit elements with a center frequency of 3 MHz and 100 receive elements with a center frequency of 18 MHz. The dimensions of the array are 15 mm in azimuth and 9 mm in elevation. The pitch is 270 μm for the transmitting elements and 135 μm for the receiving element. Pulse-echo testing of TX/RX elements corresponded with the simulation results. Real-time contrast imaging was tested using a multi-channel imaging system. The non-linear responses from microbubble contrast agents flowing through a 200 μm cellulose tube at a distance of 30 mm from the probe were clearly observed and displayed in the image. The axial beam width and CNR were calculated to be 200 μm and 18 dB, respectively. These results suggest that the prototyped co-linear array is capable of performing dual-frequency superharmonic imaging of microbubbles (“acoustic angiography”) for prostate cancer assessment.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Li, Sibo and Kim, Jinwook and Wang, Zhuochen and Jiang, Xiaoning and Kasoji, Sunny and Lindsey, Brooks and Dayton, Paul A.}, year={2015} }
 @article{li_jiang_tian_han_zhang_2015, title={A PMN- PT Micromachined 1-3 Composite Circular Array for IVUS}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0117}, abstractNote={In this paper, a single crystal PMN-PT micromachined 1-3 composite circular array (50 element, ~2.2 mm in diameter) was developed for intravascular ultrasound (IVUS) imaging. Micromachined 1-3 composites with frequency of XX MHz were first fabricated and tested. Array elements with a pitch of 140-micron were interconnected via a customized flexible circuit. Pulse-echo tests showed the average center frequency of 40 MHz and the -6 dB fractional bandwidth of 62% for array elements. The -20 dB pulse length was evaluated as 118 ns. The measured crosstalk is less than - 24 dB between adjacent elements. An image of 50 μm steel wire targets was acquired by stacking multiple A-lines. The results demonstrated beam widths exceeding 70 μm axially. Those results imply the great potential of the developed array transducer for the high frequency medical imaging.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Li, Sibo and Jiang, Xiaoning and Tian, Jian and Han, Pengdi and Zhang, Chao}, year={2015} }
 @inproceedings{wang_li_liu_geng_jiang_2015, title={A bi-frequency co-linear array transducer for biomedical ultrasound imaging}, DOI={10.1115/imece2014-38871}, abstractNote={Ultrasound imaging with high resolution and large field of depth has been increasingly adopted in medical diagnosis, surgery guidance and treatment assessment because of its relatively low cost, non-invasive and capability of real-time imaging. There is always a tradeoff between the resolution and depth of field in ultrasound imaging. Conventional ultrasound works at a particular frequency, with −6 dB fractional bandwidth of < 100%, limiting the resolution or field of depth in many ultrasound imaging cases.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2014, vol 3}, author={Wang, Z. C. and Li, S. B. and Liu, R. B. and Geng, X. C. and Jiang, X. N.}, year={2015} }
 @article{hsieh_kim_zhu_li_zhang_jiang_2015, title={A laser ultrasound transducer using carbon nanofibers-polydimethylsiloxane composite thin film}, volume={106}, ISSN={["1077-3118"]}, url={https://publons.com/publon/2826301/}, DOI={10.1063/1.4905659}, abstractNote={The photoacoustic effect has been broadly applied to generate high frequency and broadband acoustic waves using lasers. However, the efficient conversion from laser energy to acoustic power is required to generate acoustic waves with high intensity acoustic pressure (>10 MPa). In this study, we demonstrated laser generated high intensity acoustic waves using carbon nanofibers–polydimethylsiloxane (CNFs-PDMS) thin films. The average diameter of the CNFs is 132.7 ± 11.2 nm. The thickness of the CNFs film and the CNFs-PDMS composite film is 24.4 ± 1.43 μm and 57.9 ± 2.80 μm, respectively. The maximum acoustic pressure is 12.15 ± 1.35 MPa using a 4.2 mJ, 532 nm Nd:YAG pulsed laser. The maximum acoustic pressure using the CNFs-PDMS composite was found to be 7.6-fold (17.62 dB) higher than using carbon black PDMS films. Furthermore, the calculated optoacoustic energy conversion efficiency K of the prepared CNFs-PDMS composite thin films is 15.6 × 10−3 Pa/(W/m2), which is significantly higher than carbon black-PDMS thin films and other reported carbon nanomaterials, carbon nanostructures, and metal thin films. The demonstrated laser generated high intensity ultrasound source can be useful in ultrasound imaging and therapy.}, number={2}, journal={APPLIED PHYSICS LETTERS}, publisher={AIP Publishing}, author={Hsieh, Bao-Yu and Kim, Jinwook and Zhu, Jiadeng and Li, Sibo and Zhang, Xiangwu and Jiang, Xiaoning}, year={2015}, month={Jan} }
 @inproceedings{chang_kim_li_huang_jiang_2015, title={A novel laser ultrasound transducer using candle soot carbon nanoparticles}, DOI={10.1109/nano.2015.7388855}, abstractNote={Laser ultrasound provides a useful method to generate high frequency, broadband and high intensity acoustic waves. In this study, we demonstrated a novel optoacoustic transducer with high-energy conversion efficiency by using candle soot nanoparticles polydimethylsiloxane (CSPs-PDMS) composite. Carbon nanoparticles are used because of their excellent properties of light absorption and heat transfer. The mean diameter of collected candle soot carbon nanoparticles is about 40 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSPs-PDMS composite laser ultrasound transducer was excited by laser pulses, and the acoustic beam profile was measured and compared with Field II simulation results. Energy conversion coefficient and -6 dB frequency bandwidth of CSPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10-3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy and non-destructively testing applications.}, booktitle={2015 IEEE 15th International Conference on Nanotechnology (IEEE-NANO)}, author={Chang, W. Y. and Kim, J. and Li, S. B. and Huang, W. B. and Jiang, X. N.}, year={2015}, pages={1243–1246} }
 @article{zhang_li_jiang_kim_luo_geng_2015, title={Advantages and challenges of relaxor-PbTiO3 ferroelectric crystals for electroacoustic transducers – A review}, volume={68}, ISSN={0079-6425}, url={http://dx.doi.org/10.1016/J.PMATSCI.2014.10.002}, DOI={10.1016/J.PMATSCI.2014.10.002}, abstractNote={Relaxor-PbTiO3 (PT) based ferroelectric crystals with the perovskite structure have been investigated over the last few decades due to their ultrahigh piezoelectric coefficients (d33 > 1500 pC/N) and electromechanical coupling factors (k33 > 90%), far outperforming state-of-the-art ferroelectric polycrystalline Pb(Zr,Ti)O3 ceramics, and are at the forefront of advanced electroacoustic applications. In this review, the performance merits of relaxor-PT crystals in various electroacoustic devices are presented from a piezoelectric material viewpoint. Opportunities come from not only the ultrahigh properties, specifically coupling and piezoelectric coefficients, but through novel vibration modes and crystallographic/domain engineering. Figure of merits (FOMs) of crystals with various compositions and phases were established for various applications, including medical ultrasonic transducers, underwater transducers, acoustic sensors and tweezers. For each device application, recent developments in relaxor-PT ferroelectric crystals were surveyed and compared with state-of-the-art polycrystalline piezoelectrics, with an emphasis on their strong anisotropic features and crystallographic uniqueness, including engineered domain–property relationships. This review starts with an introduction on electroacoustic transducers and the history of piezoelectric materials. The development of the high performance relaxor-PT single crystals, with a focus on their uniqueness in transducer applications, is then discussed. In the third part, various FOMs of piezoelectric materials for a wide range of ultrasound applications, including diagnostic ultrasound, therapeutic ultrasound, underwater acoustic and passive sensors, tactile sensors, acoustic tweezers and ultrasonic motors, are evaluated to provide a thorough understanding of the materials’ behavior under operational conditions. Structure–property–performance relationships are then established. Finally, the impacts and challenges of relaxor-PT crystals are summarized to guide on-going and future research in the development of relaxor-PT crystals for the next generation electroacoustic transducers.}, journal={Progress in Materials Science}, publisher={Elsevier BV}, author={Zhang, Shujun and Li, Fei and Jiang, Xiaoning and Kim, Jinwook and Luo, Jun and Geng, Xuecang}, year={2015}, month={Mar}, pages={1–66} }
 @article{ma_steer_jiang_2015, title={An acoustic filter based on layered structure}, volume={106}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4915100}, DOI={10.1063/1.4915100}, abstractNote={Acoustic filters (AFs) are key components to control wave propagation in multi-frequency systems. We present a design which selectively achieves acoustic filtering with a stop band and passive amplification at the high- and low-frequencies, respectively. Measurement results from the prototypes closely match the design predictions. The AF suppresses the high frequency aliasing echo by 14.5 dB and amplifies the low frequency transmission by 8.0 dB, increasing an axial resolution from 416 to 86 μm in imaging. The AF design approach is proved to be effective in multi-frequency systems.}, number={11}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Ma, Jianguo and Steer, Michael B. and Jiang, Xiaoning}, year={2015}, month={Mar}, pages={111903} }
 @inproceedings{ma_li_wang_jiang_2015, title={Anti-matching design for wave isolation in dual frequency transducer for intravascular super-harmonic imaging}, DOI={10.1115/imece2014-38844}, abstractNote={Intravascular super-harmonic imaging of microvessels is expected to assist understanding of atherosclerotic cardiovascular disease. A dual frequency intravascular (IVUS) ultrasound transducer is a core component transmitting at low frequency and receiving high order harmonics. A significant challenge in developing high performance dual frequency IVUS transducers is the isolation of the high frequency ultrasound echoes from the low frequency element while keeping the low frequency transmission pressure. An anti-matching layer with low impedance and quarter wavelength thickness was designed based on wave propagation theory. In both KLM modeling and prototype validation, the anti-matching layer successfully suppressed the aliasing echo to less than −20 dB. Transmission pressure of the prototype transducer was still high enough for microbubble nonlinear responses. High resolution (<0.2 mm) and high CTR (>12 dB) image was generated from super-harmonic imaging, which elucidated the capability of the transducer for intravascular microvessel detection.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2014, vol 3}, author={Ma, J. G. and Li, S. B. and Wang, Z. C. and Jiang, X. N.}, year={2015} }
 @article{chang_huang_kim_li_jiang_2015, title={Candle soot nanoparticles-polydimethylsiloxane composites for laser ultrasound transducers}, volume={107}, ISSN={["1077-3118"]}, DOI={10.1063/1.4934587}, abstractNote={Generation of high power laser ultrasound strongly demands the advanced materials with efficient laser energy absorption, fast thermal diffusion, and large thermoelastic expansion capabilities. In this study, candle soot nanoparticles-polydimethylsiloxane (CSNPs-PDMS) composite was investigated as the functional layer for an optoacoustic transducer with high-energy conversion efficiency. The mean diameter of the collected candle soot carbon nanoparticles is about 45 nm, and the light absorption ratio at 532 nm wavelength is up to 96.24%. The prototyped CSNPs-PDMS nano-composite laser ultrasound transducer was characterized and compared with transducers using Cr-PDMS, carbon black (CB)-PDMS, and carbon nano-fiber (CNFs)-PDMS composites, respectively. Energy conversion coefficient and −6 dB frequency bandwidth of the CSNPs-PDMS composite laser ultrasound transducer were measured to be 4.41 × 10−3 and 21 MHz, respectively. The unprecedented laser ultrasound transduction performance using CSNPs-PDMS nano-composites is promising for a broad range of ultrasound therapy applications.}, number={16}, journal={APPLIED PHYSICS LETTERS}, author={Chang, Wei-Yi and Huang, Wenbin and Kim, Jinwook and Li, Sibo and Jiang, Xiaoning}, year={2015}, month={Oct} }
 @article{cui_poblete_cheng_yao_jiang_zhu_2015, title={Design and operation of silver nanowire based flexible and stretchable touch sensors}, volume={30}, ISSN={["2044-5326"]}, DOI={10.1557/jmr.2014.347}, abstractNote={Abstract}, number={1}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Cui, Zheng and Poblete, Felipe R. and Cheng, Guangming and Yao, Shanshan and Jiang, Xiaoning and Zhu, Yong}, year={2015}, month={Jan}, pages={79–85} }
 @article{ma_martin_li_dayton_shung_zhou_jiang_2015, title={Design factors of intravascular dual frequency transducers for super-harmonic contrast imaging and acoustic angiography}, volume={60}, ISSN={["1361-6560"]}, DOI={10.1088/0031-9155/60/9/3441}, abstractNote={Imaging of coronary vasa vasorum may lead to assessment of the vulnerable plaque development in diagnosis of atherosclerosis diseases. Dual frequency transducers capable of detection of microbubble super-harmonics have shown promise as a new contrast-enhanced intravascular ultrasound (CE-IVUS) platform with the capability of vasa vasorum imaging. Contrast-to-tissue ratio (CTR) in CE-IVUS imaging can be closely associated with low frequency transmitter performance. In this paper, transducer designs encompassing different transducer layouts, transmitting frequencies, and transducer materials are compared for optimization of imaging performance. In the layout selection, the stacked configuration showed superior super-harmonic imaging compared with the interleaved configuration. In the transmitter frequency selection, a decrease in frequency from 6.5 MHz to 5 MHz resulted in an increase of CTR from 15 dB to 22 dB when receiving frequency was kept constant at 30 MHz. In the material selection, the dual frequency transducer with the lead magnesium niobate-lead titanate (PMN-PT) 1–3 composite transmitter yielded higher axial resolution compared to single crystal transmitters (70 μm compared to 150 μm pulse length). These comparisons provide guidelines for the design of intravascular acoustic angiography transducers.}, number={9}, journal={PHYSICS IN MEDICINE AND BIOLOGY}, author={Ma, Jianguo and Martin, K. Heath and Li, Yang and Dayton, Paul A. and Shung, K. Kirk and Zhou, Qifa and Jiang, Xiaoning}, year={2015}, month={May}, pages={3441–3457} }
 @article{huang_yang_zhang_yuan_jiang_2015, title={Direct Measurement of Opening Mode Stress Intensity Factors Using Flexoelectric Strain Gradient Sensors}, volume={55}, ISSN={["1741-2765"]}, DOI={10.1007/s11340-014-9914-y}, number={2}, journal={EXPERIMENTAL MECHANICS}, author={Huang, Wenbin and Yang, Shaorui and Zhang, Ningyi and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2015}, month={Feb}, pages={313–320} }
 @article{wang_huang_jiang_martin_dayton_2015, title={Dual-frequency IVUS array for contrast enhanced intravascular ultrasound imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0545}, abstractNote={Recent studies suggest that contrast enhanced intravascular ultrasound (CE-IVUS) may be used for identifying vulnerable plaques through molecular imaging or detecting neovascularizations within a growing atherosclerotic lesion. However, typical intravascular ultrasound (IVUS) transducers operate at a high frequency band (20-60 MHz) which makes them not ideal for imaging microbubble contrast agents due to the less effective microbubble excitation at high frequencies. In this paper, a prototyped dual-frequency array for CE-IVUS was developed and tested. The prototype flat transducer array consists of a receiving array (32 elements, 30 MHz) built on the top of a transmitting array (8 sub-elements, 2.25 MHz) to achieve real-time superharmonic contrast enhanced imaging. The size of the receiving aperture was varied, tested and resultant images were compared. Images of a contrast-filled microtube can be observed clearly with only 4 receiving elements at an excitation voltage of 55 V, which indicates feasibility of CE-IVUS imaging after circularly wrapping the array for catheter integration.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Huang, Wenbin and Jiang, Xiaoning and Martin, K. Heath and Dayton, Paul A.}, year={2015} }
 @article{wang_jiang_czernuszewicz_gallippi_2015, title={Dual-frequency IVUS transducer for acoustic radiation force impulse (ARFI) imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0119}, abstractNote={Coronary atherosclerotic disease is the major cause of mortality in the United States. Elasticity imaging techniques such as acoustic radiation force impulse (ARFI) imaging using intravascular ultrasound (IVUS) transducers can be used to characterize coronary plaque. Conventional IVUS transducers with frequencies of 20 MHz - 60 MHz are not optimized for high-voltage, long-duration pulses required for ARFI imaging. In this work, a dual-frequency IVUS transducer, consisting of a 6.5 MHz “pushing” element and a 26 MHz “tracking” element, was designed and fabricated for ARFI application. In ARFI testing with a 160 V, 1000-cycle burst excitation, a displacement of 12.3 μm was detected in a phantom with a Young's modulus of 10 kPa at an axial depth of 3.5 mm. The result of this study suggests great potential of this dual-frequency IVUS transducer for intravascular ARFI imaging.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Jiang, Xiaoning and Czernuszewicz, Tomasz J. and Gallippi, Caterina M.}, year={2015} }
 @article{kim_li_kasoji_dayton_jiang_2015, title={Dual-frequency Super Harmonic Imaging Piezoelectric Transducers for Transrectal Ultrasound}, volume={9438}, ISSN={["0277-786X"]}, DOI={10.1117/12.2084459}, abstractNote={In this paper, a 2/14 MHz dual-frequency single-element transducer and a 2/22 MHz sub-array (16/48-elements linear array) transducer were developed for contrast enhanced super-harmonic ultrasound imaging of prostate cancer with the low frequency ultrasound transducer as a transmitter for contrast agent (microbubble) excitation and the high frequency transducer as a receiver for detection of nonlinear responses from microbubbles. The 1-3 piezoelectric composite was used as active materials of the single-element transducers due to its low acoustic impedance and high coupling factor. A high dielectric constant PZT ceramic was used for the sub-array transducer due to its high dielectric property induced relatively low electrical impedance. The possible resonance modes of the active elements were estimated using finite element analysis (FEA). The pulse-echo response, peak-negative pressure and bubble response were tested, followed by in vitro contrast imaging tests using a graphite-gelatin tissue-mimicking phantom. The single-element dual frequency transducer (8 × 4 × 2 mm3) showed a -6 dB fractional bandwidth of 56.5% for the transmitter, and 41.8% for the receiver. A 2 MHz-transmitter (730 μm pitch and 6.5 mm elevation aperture) and a 22 MHz-receiver (240 μm pitch and 1.5 mm aperture) of the sub-array transducer exhibited -6 dB fractional bandwidth of 51.0% and 40.2%, respectively. The peak negative pressure at the far field was about -1.3 MPa with 200 Vpp, 1-cycle 2 MHz burst, which is high enough to excite microbubbles for nonlinear responses. The 7th harmonic responses from micro bubbles were successfully detected in the phantom imaging test showing a contrast-to-tissue ratio (CTR) of 16 dB.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS 2015}, author={Kim, Jinwook and Li, Sibo and Kasoji, Sandeep and Dayton, Paul A. and Jiang, Xiaoning}, year={2015} }
 @article{lindsey_martin_dayton_ma_wang_jiang_2015, title={Dual-frequency intravascular ultrasound imaging of microbubble contrast agents: Ex vivo and in vivo demonstration}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0044}, abstractNote={Development of atherosclerotic plaques and related cardiac events are correlated with increased development of vasa vasorum, however, no currently-available diagnostic imaging method has been demonstrated effective at identifying vulnerable plaques. We present a new intravascular ultrasound (IVUS) imaging method using a dual-frequency transducer to visualize contrast flow in microvessels with high specificity. This method uses a specialized transducer capable of exciting contrast agents at a low frequency (5.5 MHz) and receiving superharmonic echoes at a much higher frequency (37 MHz). This dual-frequency transducer was used to image a cellulose micro-tube external to an ex vivo porcine artery and also using the chorioallantoic membrane of a developing chicken embryo. Using dual-frequency contrast-specific imaging, we were able to resolve vessels of a similar size to those found in vulnerable atherosclerotic plaques with clinically-relevant attenuation. The results of this study suggest contrast-specific intravascular ultrasound imaging for the detection of vulnerable plaques in atherosclerosis may provide additional diagnostic information.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Lindsey, Brooks D. and Martin, K. Heath and Dayton, Paul A. and Ma, Jianguo and Wang, Zhuochen and Jiang, Xiaoning}, year={2015} }
 @article{jian_li_huang_cui_jiang_2015, title={Electromechanical response of micromachined 1-3 piezoelectric composites: Effect of etched piezo-pillar slope}, volume={26}, ISSN={["1530-8138"]}, DOI={10.1177/1045389x14546657}, abstractNote={ Micromachined single-crystal piezoelectric 1-3 composites are known for high electromechanical coupling coefficients, low acoustic impedance, high processing precision and uniformity, which are desired for high-frequency ultrasound transducers. In this article, based on Smith and Auld’s 1-3 composite thickness-mode oscillation model, the effect of etched side wall slope on the electromechanical characteristics of micromachined piezoelectric 1-3 composites was studied. In specific, strain constant, stiffness, dielectric constant, electromechanical coupling coefficient, acoustic impedance, longitudinal velocity, and frequency of micromachined 1-3 composites were deduced using the developed model. The analytical model was then verified by a COMSOL simulation and experimental measurements of a micromachined composite sample with pitch of 15.9 µm, thickness of 42.8 µm, and etched pillar slope angle of 83.8°. The measured center frequency was 49.05 MHz, electromechanical coupling coefficient was 0.66, dielectric constant was 1178, and strain constant was 26.90 C/m2, which all agreed well with the analytical calculations. These results will be helpful in design and fabrication of high-frequency micromachined ultrasound transducers. }, number={15}, journal={JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES}, author={Jian, Xiaohua and Li, Sibo and Huang, Wenbin and Cui, Yaoyao and Jiang, Xiaoning}, year={2015}, month={Oct}, pages={2011–2019} }
 @inproceedings{guo_jiang_2015, title={Enhancement of ultrasonic cavitation yield by dual frequency sonication}, DOI={10.1115/imece2014-39641}, abstractNote={This paper reports the experimental study on the enhanced cavitation yield via dual-frequency ultrasonic sonication and the multi-frequency single-bubble cavitation bubble modeling. The cavitation yield was characterized using the PCD (passive cavitation detection) method. A dual-frequency (1.5 MHz/3 MHz) pulse ultrasound was used in the tests. It was found that the sonication of dual-frequency ultrasound can produce a significant increase in cavitation yield compared with single-frequency irradiation. The possible mechanisms of the enhanced effect were explained by the single-bubble cavitation model, where the calculated radiated pressure generated by acoustic bubble cavitation was found greater in dual-frequency cases. The findings from this paper are promising for the design of multi-frequency ultrasound system with enhanced cavitation for a number of biomedical, biological and chemical processing applications.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2014, vol 3}, author={Guo, S. J. and Jiang, X. N.}, year={2015} }
 @article{kim_kim_dalmau_schlesser_preble_jiang_2015, title={High-Temperature Electromechanical Characterization of AlN Single Crystals}, volume={62}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2015.007252}, abstractNote={Hexagonal AlN is a non-ferroelectric material and does not have any phase transition up to its melting point (>2000°C), which indicates the potential use of AlN for high-temperature sensing. In this work, the elastic, dielectric, and piezoelectric constants of AlN single crystals were investigated at elevated temperatures up to 1000°C by the resonance method. We used resonators of five different modes to obtain a complete set of material constants of AlN single crystals. The electrical resistivity of AlN at elevated temperature (1000°C) was found to be greater than 5 × 1010 Ω · cm. The resonance cm. frequency of the resonators, which was mainly determined by the elastic compliances, decreased linearly with increasing temperature, and was characterized by a relatively low temperature coefficient of frequency, in the range of -20 to -36 ppm/°C. For all the investigated resonator modes, the elastic constants and the electromechanical coupling factors exhibited excellent temperature stability, with small variations over the full temperature range, <;11.2% and <;17%, respectively. Of particular significance is that due to the pyroelectricity of AlN, both the dielectric and the piezoelectric constants had high thermal resistivity even at extreme high temperature (1000°C). Therefore, high electrical resistivity, temperature independence of electromechanical properties, as well as high thermal resistivity of the elastic, dielectric, and piezoelectric properties, suggest that AlN single crystals are a promising candidate for high-temperature piezoelectric sensing applications.}, number={10}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Kim, Taeyang and Kim, Jinwook and Dalmau, Rafael and Schlesser, Raoul and Preble, Edward and Jiang, Xiaoning}, year={2015}, month={Oct}, pages={1880–1887} }
 @article{kim_li_kasoji_dayton_jiang_2015, title={Phantom evaluation of stacked-type dual-frequency 1-3 composite transducers: A feasibility study on intracavitary acoustic angiography}, volume={63}, ISSN={["1874-9968"]}, DOI={10.1016/j.ultras.2015.06.009}, abstractNote={In this paper, we present phantom evaluation results of a stacked-type dual-frequency 1-3 piezoelectric composite transducer as a feasibility study for intracavitary acoustic angiography. Our previous design (6.5/30 MHz PMN-PT single crystal transducer) for intravascular contrast ultrasound imaging exhibited a contrast-to-tissue ratio (CTR) of 12 dB with a penetration depth of 2.5 mm. For improved penetration depth (>3 mm) and comparable contrast-to-tissue ratio (>12 dB), we evaluated a lower frequency 2/14 MHz PZT 1-3 composite transducer. Superharmonic imaging performance of this transducer and a detailed characterization of key parameters for acoustic angiography are presented. The 2/14 MHz arrangement demonstrated a -6 dB fractional bandwidth of 56.5% for the transmitter and 41.8% for the receiver, and produced sufficient peak-negative pressures (>1.5 MPa) at 2 MHz to induce a strong nonlinear harmonic response from microbubble contrast agents. In an in-vitro contrast ultrasound study using a tissue mimicking phantom and 200 μm cellulose microvessels, higher harmonic microbubble responses, from the 5th through the 7th harmonics, were detected with a signal-to-noise ratio of 16 dB. The microvessels were resolved in a two-dimensional image with a -6dB axial resolution of 615 μm (5.5 times the wavelength of 14 MHz waves) and a contrast-to-tissue ratio of 16 dB. This feasibility study, including detailed explanation of phantom evaluation and characterization procedures for key parameters, will be useful for the development of future dual-frequency array transducers for intracavitary acoustic angiography.}, journal={ULTRASONICS}, author={Kim, Jinwook and Li, Sibo and Kasoji, Sandeep and Dayton, Paul A. and Jiang, Xiaoning}, year={2015}, month={Dec}, pages={7–15} }
 @article{di_kim_hu_jiang_gu_2015, title={Spatiotemporal drug delivery using laser-generated-focused ultrasound system}, volume={220}, ISSN={["1873-4995"]}, DOI={10.1016/j.jconrel.2015.08.033}, abstractNote={Laser-generated-focused ultrasound (LGFU) holds promise for the high-precision ultrasound therapy owing to its tight focal spot, broad frequency band, and stable excitation with minimal ultrasound-induced heating. We here report the development of the LGFU as a stimulus for promoted drug release from microgels integrated with drug-loaded polymeric nanoparticles. The pulsed waves of ultrasound, generated by a carbon black/polydimethylsiloxane (PDMS)-photoacoustic lens, were introduced to trigger the drug release from alginate microgels encapsulated with drug-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles. We demonstrated the antibacterial capability of this drug delivery system against Escherichia coli by the disk diffusion method, and antitumor efficacy toward the HeLa cell-derived tumor spheroids in vitro. This novel LGFU-responsive drug delivery system provides a simple and remote approach to precisely control the release of therapeutics in a spatiotemporal manner and potentially suppress detrimental effects to the surrounding tissue, such as thermal ablation.}, journal={JOURNAL OF CONTROLLED RELEASE}, author={Di, Jin and Kim, Jinwook and Hu, Quanyin and Jiang, Xiaoning and Gu, Zhen}, year={2015}, month={Dec}, pages={592–599} }
 @article{suo_guo_lin_jiang_jing_2015, title={Thrombolysis using multi-frequency high intensity focused ultrasound at MHz range: an in vitro study}, volume={60}, ISSN={["1361-6560"]}, DOI={10.1088/0031-9155/60/18/7403}, abstractNote={High intensity focused ultrasound (HIFU) based thrombolysis has emerged as a promising drug-free treatment approach for ischemic stroke. The large amount of acoustic power required by this approach, however, poses a critical challenge to the future clinical translation. In this study, multi-frequency acoustic waves at MHz range (near 1.5 MHz) were introduced as HIFU excitations to reduce the required power for treatment as well as the treatment time. In vitro bovine blood clots weighing around 150 mg were treated by single-frequency and multi-frequency HIFU. The pulse length was 2 ms for all experiments except the ones where the duty cycle was changed. It was found that dual-frequency thrombolysis efficiency was statistically better than single-frequency under the same acoustic power and excitation condition. When varying the acoustic power but fixing the duty cycle at 5%, it was found that dual-frequency ultrasound can save almost 30% power in order to achieve the same thrombolysis efficiency. In the experiment where the duty cycle was increased from 0.5% to 10%, it was shown that dual-frequency ultrasound can achieve the same thrombolysis efficiency with only half of the duty cycle of single-frequency. Dual-frequency ultrasound could also accelerate the thrombolysis by a factor of 2–4 as demonstrated in this study. No significant differences were found between dual-frequencies with different frequency differences (0.025, 0.05, and 0.1 MHz) and between dual-frequency and triple-frequency. The measured cavitation doses of dual-frequency and triple-frequency excitations were at about the same level but both were significantly higher than that of single-frequency.}, number={18}, journal={PHYSICS IN MEDICINE AND BIOLOGY}, author={Suo, Dingjie and Guo, Sijia and Lin, Weili and Jiang, Xiaoning and Jing, Yun}, year={2015}, month={Sep}, pages={7403–7418} }
 @article{li_ma_martin_choi_dayton_jiang_shung_zhou_2014, title={A Configurable Dual-Frequency Transmit/Receive System for Acoustic Angiography Imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0180}, abstractNote={Acoustic angiography is a high-resolution imaging modality for small vascular structure. It utilizes the nonlinear backscatter of microbubble contrast agents (MCAs) to delineate blood vessels. In acoustic angiography, where MCAs are insonified with high rarefractional pressures at resonance frequency (6.5MHz), high-order harmonics (30 MHz) become more evident and can be utilized to produce high-resolution images for detecting small vascular structures. We developed a configurable dual-frequency system platform dedicated to acoustic angiography. The system consists of pulse generation, data acquisition and signal processing blocks. It is controlled by a field programmable gate array (FPGA), which enables flexible programming, and many on-board processing and stimulation modes. The system was shown to be capable of acoustic angiography as well as traditional B-mode imaging.}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Li, Yang and Ma, Jianguo and Martin, K. Heath and Choi, Hojong and Dayton, Paul A. and Jiang, Xiaoning and Shung, K. Kirk and Zhou, Qifa}, year={2014}, pages={731–733} }
 @article{kwon_huang_zhang_yuan_jiang_2014, title={A new type of microphone using flexoelectric barium strontium titnate}, volume={9062}, ISSN={["1996-756X"]}, DOI={10.1117/12.2045072}, abstractNote={A flexoelectric bridge-structured microphone using bulk barium strontium titanate (Ba0.65Sr0.35TiO3 or BST) ceramic was investigated in this study. The flexoelectric microphone was installed in an anechoic box and exposed to the sound pressure emitted from a loud speaker. Charge sensitivity of the flexoelectric microphone was measured and calibrated using a reference microphone. The 1.5 mm×768 μm×50 μm micro-machined bridge-structured flexoelectric microphone has a sensitivity of 0.92 pC/Pa, while its resonance frequency was calculated to be 98.67 kHz. The analytical and experimental results show that the flexoelectric microphone has both high sensitivity and broad bandwidth, indicating that flexoelectric microphones are potential candidates for many applications.}, journal={SMART SENSOR PHENOMENA, TECHNOLOGY, NETWORKS, AND SYSTEMS INTEGRATION 2014}, author={Kwon, Seol Ryung and Huang, Wenbin and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014} }
 @article{ma_martin_dayton_jiang_2014, title={A preliminary engineering design of intravascular dual-frequency transducers for contrast-enhanced acoustic angiography and molecular imaging}, volume={61}, DOI={10.1109/tuffc.2014.6805699}, abstractNote={Current intravascular ultrasound (IVUS) probes are not optimized for contrast detection because of their design for high-frequency fundamental-mode imaging. However, data from transcutaneous contrast imaging suggests the possibility of utilizing contrast ultrasound for molecular imaging or vasa vasorum assessment to further elucidate atherosclerotic plaque deposition. This paper presents the design, fabrication, and characterization of a small-aperture (0.6 × 3 mm) IVUS probe optimized for high-frequency contrast imaging. The design utilizes a dual-frequency (6.5 MHz/30 MHz) transducer arrangement for exciting microbubbles at low frequencies (near their resonance) and detecting their broadband harmonics at high frequencies, minimizing detected tissue backscatter. The prototype probe is able to generate nonlinear microbubble response with more than 1.2 MPa of rarefractional pressure (mechanical index: 0.48) at 6.5 MHz, and is also able to detect microbubble response with a broadband receiving element (center frequency: 30 MHz, -6-dB fractional bandwidth: 58.6%). Nonlinear super-harmonics from microbubbles flowing through a 200-μm-diameter micro-tube were clearly detected with a signal-to-noise ratio higher than 12 dB. Preliminary phantom imaging at the fundamental frequency (30 MHz) and dual-frequency super-harmonic imaging results suggest the promise of small aperture, dual-frequency IVUS transducers for contrast-enhanced IVUS imaging.}, number={5}, journal={IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control}, author={Ma, J. G. and Martin, K. H. and Dayton, P. A. and Jiang, X. N.}, year={2014}, pages={870–880} }
 @article{huang_kwon_zhang_yuan_jiang_2014, title={A trapezoidal flexoelectric accelerometer}, volume={25}, ISSN={["1530-8138"]}, DOI={10.1177/1045389x13491021}, abstractNote={ In this article a new acceleration sensor using flexoelectric barium strontium titanate cantilever was designed, fabricated, and tested for vibration monitoring. The flexoelectric sensors were configured as a trapezoidal unimorph with a barium strontium titanate layer bonded onto a steel substrate. Seismic mass was attached to the unimorph tip to amplify the transverse flexoelectric response of the barium strontium titanate layer. The theoretical model was developed and validated by vibration tests using the prototyped flexoelectric unimorph. The prototyped accelerometer with thickness of 0.1 mm and length and width in millimeters showed a stable sensitivity of 0.84 pC/g over the frequency range of 100 Hz–1.6 kHz. The aging property of the flexoelectric material was demonstrated to be much better than that of the reported piezoelectric materials right after poling. Scaling effect analysis was also performed for flexoelectric unimorphs. The test results and initial scaling effect analysis indicate that micro/nano flexoelectric sensing holds promise for a broad range of applications. }, number={3}, journal={JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES}, author={Huang, Wenbin and Kwon, Seol-Ryung and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014}, month={Feb}, pages={271–277} }
 @article{czernuszcwicz_gallippi_wang_ma_jiang_2014, title={Acoustic radiation force (ARF) generation with a novel dual-frequency intravascular transducer.}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0569}, abstractNote={Atherosclerosis and coronary artery disease remain the leading cause of death in the US. Coronary plaque is visualized with intravascular ultrasound (IVUS) and is typically implemented with high center frequencies (>20 MHz) for superior spatial resolution. Coronary plaque characterization may be improved by implementing elasticity imaging techniques such as acoustic radiation force impulse (ARFI) imaging using IVUS transducers. In this work we propose to extend ARFI imaging to a novel, dual-frequency small-aperture transducer design that includes a low-frequency “pushing” element and a high-frequency “tracking” element. A 40 MHz element (0.6 mm × 0.6 mm) was integrated onto a 5 MHz element (0.6 mm × 3 mm). Both elements of the transducer were fabricated from single crystal PMN-PT and the whole transducer was mounted on a 20 gauge needle tip. ARF-induced motion from the low-frequency element was quantified using optical tracking methods in a translucent phantom (~8 kPa) containing embedded graphite microparticles. Displacements induced by ARF excitations with 300, 600, 900, and 1200 cycles (5 MHz, 190 V) were captured and compared to baseline. Median (inter-quartile range) peak displacements for 300, 600, 900, and 1200 cycles were 0.33 (0.27 - 0.39) μm, 0.72 (0.62 - 0.87) μm, 1.1 (1.0 - 1.3) μm, and 1.6 (1.43 - 1.75) μm, respectively. In another phantom, 40 MHz pulse/echo RF lines were captured to demonstrate backscatter sensitivity. The results of this study show that ARF generation and high-resolution tracking is feasible on a small-aperture transducer fit for IVUS implementation.}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Czernuszcwicz, Tomasz J. and Gallippi, Caterina M. and Wang, Zhuochen and Ma, Jianguo and Jiang, Xiaoning}, year={2014}, pages={2284–2287} }
 @inproceedings{kim_jiang_2014, title={Acoustic wave microsensor array for tactile sensing}, DOI={10.1115/imece2013-66098}, abstractNote={Tactile perception is a critical requirement for surgery procedures such as minimally invasive surgery (MIS). In this study, an acoustic wave tactile sensor array for force and shear modulus sensing was investigated. This device can sense the magnitude of the applied force change and the tissue’s shear modulus change by means of detecting an electrical impedance change. The 6×6 array with a pitch of 1.3 mm was fabricated using a face-shear mode PMN-PT piezoelectric resonator which is highly sensitive to acoustic impedance load. External forces (0–5 N) were applied to the sensor and the electric impedance shift was measured. The sensitivity was found to be 56.87 Ohm/N. Imaging test results for different force and load stiffnesses were also obtained. The proposed tactile sensing technique is also favorable for a number of other biomedical applications including haptic sensors for the robotic surgery and artificial skin or fingers.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2013, vol 3B}, author={Kim, K. and Jiang, X. N.}, year={2014} }
 @article{wang_ma_jiang_martin_dayton_2014, title={An array transmitter for dual-frequency contrast enhanced intravascular ultrasound imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0524}, abstractNote={Recent studies suggests that contrast ultrasound for molecular imaging or vasa vasorum (VV) assessment may be promising in identification of vulnerable plaques. However, conventional intravascular ultrasound (IVUS) transducers with frequency of 15 MHz - 60 MHz are not optimized for imaging with micro bubble contrast agents due to the ineffective micro bubble excitation at high frequencies and poor signal separation from tissue. This paper presents design and fabrication of a lateral mode transducer array with center frequency of 2 MHz for contrast enhanced IVUS (CE-IVUS) imaging, which can generate sufficient pressure to excite microbubbles more effectively and therefore could be used for dual-frequency microbubble superharmonic imaging, or `acoustic angiography'. Several commercial transducers with central frequency of 15 MHz, 20 MHz and 25 MHz were used as receivers to receive the contrast signal. In the contrast testing, the high frequency echo of the nonlinear response from microbubbles in a micro-tube with diameter of 0.2 mm was detected. The maximum contrast to noise ratio was 12.2 dB. The results show that superharmonic signals (over 9th harmonic) can be received; suggesting good resolution and signal separation in contrast enhanced IVUS imaging.}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Ma, Jianguo and Jiang, Xiaoning and Martin, Karl Heath and Dayton, Paul A.}, year={2014}, pages={2104–2107} }
 @article{shu_huang_kwon_wang_li_wei_zhang_lanagan_yao_jiang_2014, title={Converse flexoelectric coefficient f(1212) in bulk Ba0.67Sr0.33TiO3}, volume={104}, ISSN={["1077-3118"]}, DOI={10.1063/1.4882060}, abstractNote={The converse flexoelectric effect, referred as the electric field gradient induced strain, widely exists in dielectric materials, but its experimental studies have been reported by few research groups so far. In this Letter, we report our studies on the converse flexoelectric behavior of (Ba0.67Sr0.33)TiO3 ceramics and present the measured value of its flexoelectric coefficient f1212. In the experiments, the electric field gradient was generated by applying an electric field across the two lateral sides of trapezoid (Ba0.67Sr0.33)TiO3 samples. The shear displacement was measured using a laser vibrometer. The converse flexoelectric coefficient f1212 was found to be 124 ± 14 μC/m at room temperature. This result was in good agreement with the theoretical prediction of the flexoelectricity of the (Ba, Sr)TiO3 ceramics.}, number={23}, journal={APPLIED PHYSICS LETTERS}, author={Shu, Longlong and Huang, Wenbin and Kwon, Seol Ryung and Wang, Zhao and Li, Fei and Wei, Xiaoyong and Zhang, Shujun and Lanagan, Michael and Yao, Xi and Jiang, Xiaoning}, year={2014}, month={Jun} }
 @inproceedings{johnson_kim_zhang_jiang_2014, title={Crack propagation testing using a YCOB acoustic emission sensor}, volume={9063}, DOI={10.1117/12.2045091}, abstractNote={Piezoelectric crystals are popular for passive sensors, such as accelerometers and acoustic emission sensors, due to their robustness and high sensitivity. These sensors are widespread in structural health monitoring among civil and industrial structures, but there is little application in high temperature environments (e.g. > 1000°C) due to the few materials that are capable of operating at elevated temperatures. Most piezoelectric materials suffer from a loss of electric properties above temperatures in the 500-700°C range, but rare earth oxyborate crystals, such as Yttrium calcium oxyborate (YCOB), retain their piezoelectric properties above 1000 °C. Our previous research demonstrated that YCOB can be used to detect transient lamb waves via Hsu-Nielsen tests, which replicate acoustic emission waves, up to 1000°C. In this paper, YCOB piezoelectric acoustic emission sensors were tested for their ability to detect crack progression at elevated temperatures. The sensor was fabricated using a YCOB single crystal and Inconel electrodes and wires. The sensor was mounted onto a stainless steel bar substrate, which was machined to include a pre-crack notch. A dynamic load was induced on the bar with a shaker in order to force the crack to advance along the thickness of the substrate. The obtained raw data was processed and analyzed in the frequency domain and compared to the Lamb wave modes that were evaluated in previous Hsu-Nielsen testing for the substrate.}, booktitle={Nondestructive characterization for composite materials, aerospace engineering, civil infrastructure, and homeland security 2014}, author={Johnson, J. A. and Kim, K. and Zhang, S. J. and Jiang, X. N.}, year={2014} }
 @article{huang_yang_zhang_yuan_jiang_2014, title={Cracks Monitoring and Characterization Using Ba0.64Sr0.36TiO3 Flexoelectric Strain Gradient Sensors}, volume={9061}, ISSN={["0277-786X"]}, DOI={10.1117/12.2045166}, abstractNote={This paper presents a new method for monitoring and characterizing cracks using Ba0.64Sr0.36TiO3 flexoelectric strain gradient sensors. Firstly, strain gradient field around the mixed mode asymptotic crack tip was analyzed, followed by the derivation of induced flexoelectric polarization in the strain gradient sensors attached in the vicinity of a crack tip. It was found that the flexoelectric polarization of the sensor can be expressed as a function of the stress intensity factors of crack and relative coordinates between the sensor and crack. Given the information of the crack size, further analysis demonstrates that the location of the crack can be traced through the calculation based on flexoelectric outputs of the distributed sensors. A specimen with Mode-I crack was then prepared with two strain gradient sensors (4.7 mm × 0.9 mm × 0.3 mm) attached close to the crack tip to verify the analytical model for detection of cracks. The experimental results yield accurate location of the crack, confirming that flexoelectric strain gradient sensing can be a good avenue for monitoring cracks.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2014}, author={Huang, Wenbin and Yang, Shaorui and Zhang, Ningyi and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014} }
 @article{li_jiang_tian_han_2014, title={Development of Dual-layer Micromachined Composite Transducers for Broadband Ultrasound Imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0164}, abstractNote={We presented in this paper the development of micromachined 1-3 composite dual layer transducers for multifrequency imaging. The effective electromechanical coupling coefficient and acoustic impedance of the micromachined PMN-PT 1-3 composite material was measured to be 0.73 and 18 MRayl, respectively. Based on the material, a dual-layer transducer prototype was developed. The probe was operated at both 15 MHz and 48 MHz. To characterize the transducer, pulse echo test was conducted, achieved a 73% and 70% bandwidth at low and high resonance, respectively. At fundamental mode, it showed transmitting sensitivity of 26 KPa/V, These results suggested great potential for medical broadband imaging applications.}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Li, Sibo and Jiang, Xiaoning and Tian, Jian and Han, Pengdi}, year={2014}, pages={667–670} }
 @article{kim_li_jiang_kasoji_dayton_2014, title={Development of Transmitters in Dual-Frequency Transducers for Interventional Contrast Enhanced Imaging and Acoustic Angiography}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0167}, abstractNote={Spatial limitation can be a challenge to interventional ultrasound transducers for dual-frequency contrast-enhanced ultrasound imaging, or acoustic angiography. A low frequency (<; 3 MHz) transmission with moderate peak negative pressure (PNP) and short pulse length is not easily attainable within limited dimensions. In this paper, a new design of the low frequency transmitter of dual-frequency transducers is presented. 1-3 composites for interventional transmitter design were analyzed by the Krimholtz-Leedom-Matthaei (KLM) model and finite element analysis (FEA). The dual frequency transducer prototype with a 2 MHz 1-3 composite transmitter and a 14 MHz receiver was fabricated and characterized, followed by microbubble detection tests. The transmitter showed the peak negative pressure (PNP) of -1.5 MPa. The -6 dB pulse echo fractional bandwidth for the transmitter and receiver were 61 % and 45 %, respectively. The prototyped dual frequency transducer was used to successfully excite microbubbles and to detect super harmonic responses from microbubbles. The measured harmonic signal showed a 12 dB contrast-to-noise ratio (CNR).}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Kim, Jinwook and Li, Sibo and Jiang, Xiaoning and Kasoji, Sandeep and Dayton, Paul A.}, year={2014}, pages={679–682} }
 @article{wang_yuan_jiang_jing_wang_2014, title={Disruption of microalgal cells using high-frequency focused ultrasound}, volume={153}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2013.11.054}, abstractNote={The objective of this study was to evaluate the effectiveness of high-frequency focused ultrasound (HFFU) in microalgal cell disruption. Two microalgal species including Scenedesmus dimorphus and Nannochloropsis oculata were treated by a 3.2-MHz, 40-W focused ultrasound and a 100-W, low-frequency (20kHz) non-focused ultrasound (LFNFU). The results demonstrated that HFFU was effective in the disruption of microalgal cells, indicated by significantly increased lipid fluorescence density, the decrease of cell sizes, and the increase of chlorophyll a fluorescence density after treatments. Compared with LFNFU, HFFU treatment was more energy efficient. The combination of high and low frequency treatments was found to be even more effective than single frequency treatment at the same processing time, indicating that frequency played a critical role in cell disruption. In both HFFU and LFNFU treatments, the effectiveness of cell disruption was found to be dependent on the cell treated.}, journal={BIORESOURCE TECHNOLOGY}, author={Wang, Meng and Yuan, Wenqiao and Jiang, Xiaoning and Jing, Yun and Wang, Zhuochen}, year={2014}, month={Feb}, pages={315–321} }
 @article{di_price_gu_jiang_jing_gu_2014, title={Drug Delivery: Ultrasound-Triggered Regulation of Blood Glucose Levels Using Injectable Nano-Network (Adv. Healthcare Mater. 6/2014)}, volume={3}, ISSN={2192-2640}, url={http://dx.doi.org/10.1002/ADHM.201470027}, DOI={10.1002/ADHM.201470027}, abstractNote={On page 811, Y. Jing, Z. Gu and co-workers present the integration of an injectable nano-network with a focused ultrasound system (FUS) which can remotely regulate insulin release both in vitro and in vivo. Serving as a synthetic insulin reservoir, the nano-network consisting of adhesive biodegradable nanoparticles promotes insulin release upon FUS triggers in a pulsatile, remote and non-invasive control manner. Image courtesy of Dwayne Martin.}, number={6}, journal={Advanced Healthcare Materials}, publisher={Wiley}, author={Di, Jin and Price, Jennifer and Gu, Xiao and Jiang, Xiaoning and Jing, Yun and Gu, Zhen}, year={2014}, month={Jun}, pages={789–789} }
 @article{ma_jiang_martin_dayton_li_zhou_2014, title={Dual Frequency Transducers for Intravascular Ultrasound Super-harmonic Imaging and Acoustic Angiography}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0166}, abstractNote={Imaging of coronary vasa vasorum may lead to assessment of the vulnerable plaque development in diagnosis of atherosclerosis diseases. Intravascular ultrasound (IVUS) imaging transducers capable of detecting microvessels via nonlinear contrast imaging could provide valuable diagnostic information, however such transducers are not yet produced commercially. Dual-frequency transducers capable of detection of microbubble super-harmonics have shown promise as a new contrast-enhanced IVUS (CE-IVUS) platform. Contrast-to-tissue ratio (CTR) in CE-IVUS imaging can be closely associated with the low frequency transmitter performance. In this paper, multiple dual frequency IVUS transducers with different transmission frequencies (6.5 and 5 MHz) and different materials (PMN-PT single crystals and 1-3 composite) were developed and evaluated. All transducer structures were constructed with the 30 MHz high frequency reception element in front of the low frequency transmission element. Super-harmonic imaging was carried out using a tissue mimicking phantom. With similar peak negative pressures, the lower transmission frequency transducers generated higher CTR (23 dB for 5 MHz transmission). With similar input excitations, the PMN-PT 1-3 composite produced higher resolution (70 μm for 1-cycle burst excitation) than single crystal ones (> 150 μm). Dual frequency transducers with 5 MHz transmitters made of PMN-PT 1-3 composite are preferable in the CE-IVUS imaging.}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Ma, Jianguo and Jiang, Xiaoning and Martin, Karl H. and Dayton, Paul A. and Li, Yang and Zhou, Qifa}, year={2014}, pages={675–678} }
 @misc{martin_lindsey_ma_lee_li_foster_jiang_dayton_2014, title={Dual-Frequency Piezoelectric Transducers for Contrast Enhanced Ultrasound Imaging}, volume={14}, ISSN={["1424-8220"]}, DOI={10.3390/s141120825}, abstractNote={For many years, ultrasound has provided clinicians with an affordable and effective imaging tool for applications ranging from cardiology to obstetrics. Development of microbubble contrast agents over the past several decades has enabled ultrasound to distinguish between blood flow and surrounding tissue. Current clinical practices using microbubble contrast agents rely heavily on user training to evaluate degree of localized perfusion. Advances in separating the signals produced from contrast agents versus surrounding tissue backscatter provide unique opportunities for specialized sensors designed to image microbubbles with higher signal to noise and resolution than previously possible. In this review article, we describe the background principles and recent developments of ultrasound transducer technology for receiving signals produced by contrast agents while rejecting signals arising from soft tissue. This approach relies on transmitting at a low-frequency and receiving microbubble harmonic signals at frequencies many times higher than the transmitted frequency. Design and fabrication of dual-frequency transducers and the extension of recent developments in transducer technology for dual-frequency harmonic imaging are discussed.}, number={11}, journal={SENSORS}, author={Martin, K. Heath and Lindsey, Brooks D. and Ma, Jianguo and Lee, Mike and Li, Sibo and Foster, F. Stuart and Jiang, Xiaoning and Dayton, Paul A.}, year={2014}, month={Nov}, pages={20825–20842} }
 @article{huang_shu_kwon_zhang_yuan_jiang_2014, title={Fabrication and measurement of a flexoelectric micro-pyramid composite}, volume={4}, ISSN={["2158-3226"]}, DOI={10.1063/1.4904024}, abstractNote={A fabrication method by combining precision mechanical dicing and wet etching was developed to prepare micro-pyramid structures based on (Ba0.67Sr0.33)TiO3 ceramics. The effective piezoelectric properties of flexoelectric pyramid structures in ten micrometers scale were investigated and measured through converse flexoelectric effect. The scaling effect of the flexoelectric response was demonstrated as the structure size shrinks down. The results do suggest the great potential of flexoelectric micro pyramids as an alternative to lead-free piezoelectric material.}, number={12}, journal={AIP ADVANCES}, author={Huang, Wenbin and Shu, Longlong and Kwon, Seol Ryung and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2014}, month={Dec} }
 @article{kwon_huang_shu_yuan_maria_jiang_2014, title={Flexoelectricity in barium strontium titanate thin film}, volume={105}, ISSN={["1077-3118"]}, DOI={10.1063/1.4898139}, abstractNote={Flexoelectricity, the linear coupling between the strain gradient and the induced electric polarization, has been intensively studied as an alternative to piezoelectricity. Especially, it is of interest to develop flexoelectric devices on micro/nano scales due to the inherent scaling effect of flexoelectric effect. Ba0.7Sr0.3TiO3 thin film with a thickness of 130 nm was fabricated on a silicon wafer using a RF magnetron sputtering process. The flexoelectric coefficients of the prepared thin films were determined experimentally. It was revealed that the thin films possessed a transverse flexoelectric coefficient of 24.5 μC/m at Curie temperature (∼28 °C) and 17.44 μC/m at 41 °C. The measured flexoelectric coefficients are comparable to that of bulk BST ceramics, which are reported to be 10–100 μC/m. This result suggests that the flexoelectric thin film structures can be effectively used for micro/nano-sensing devices.}, number={14}, journal={APPLIED PHYSICS LETTERS}, author={Kwon, Seol Ryung and Huang, Wenbin and Shu, Longlong and Yuan, Fuh-Gwo and Maria, Jon-Paul and Jiang, Xiaoning}, year={2014}, month={Oct} }
 @article{li_shu_huang_jiang_wang_2014, title={Giant flexoelectricity in Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite}, volume={105}, ISSN={["1077-3118"]}, DOI={10.1063/1.4899060}, abstractNote={Enhanced flexoelectricity in perovskite ceramics and single crystals has been reported before. In this letter, 3-3 ceramic-ceramic Ba0.6Sr0.4TiO3/Ni0.8Zn0.2Fe2O4 composite with a colossal permittivity was employed in the conventional pure bending experiment in order to examine the transverse flexoelectric response. The measured flexoelectric coefficient at 30 Hz is 128 μC/m and varies to 16 μC/m with the frequency increasing from 30 Hz to 120 Hz, mainly due to the inverse correlation between the permittivity and the frequency. This result reveals the permittivity dependence of flexoelectric coefficient in the frequency dispersion materials, suggesting that the giant permittivity composites can be good flexoelectric materials.}, number={16}, journal={APPLIED PHYSICS LETTERS}, author={Li, Yong and Shu, Longlong and Huang, Wenbin and Jiang, Xiaoning and Wang, Hong}, year={2014}, month={Oct} }
 @misc{jiang_kim_zhang_johnson_salazar_2014, title={High-Temperature Piezoelectric Sensing}, volume={14}, ISSN={["1424-8220"]}, DOI={10.3390/s140100144}, abstractNote={Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented.}, number={1}, journal={SENSORS}, author={Jiang, Xiaoning and Kim, Kyungrim and Zhang, Shujun and Johnson, Joseph and Salazar, Giovanni}, year={2014}, month={Jan}, pages={144–169} }
 @article{johnson_kim_zhang_wu_jiang_2014, title={High-temperature acoustic emission sensing tests using a yttrium calcium oxyborate sensor}, volume={61}, DOI={10.1109/tuffc.2014.6805694}, abstractNote={Piezoelectric materials have been broadly utilized in acoustic emission sensors, but are often hindered by the loss of piezoelectric properties at temperatures in the 500°C to 700°C range or higher. In this paper, a piezoelectric acoustic emission sensor was designed and fabricated using yttrium calcium oxyborate (YCOB) single crystals, followed by Hsu-Nielsen tests for high-temperature (>700°C) applications. The sensitivity of the YCOB sensor was found to have minimal degradation with increasing temperature up to 1000°C. During Hsu-Nielsen tests with a steel bar, this YCOB acoustic sensor showed the ability to detect zero-order symmetric and antisymmetric modes at 30 and 120 kHz, respectively, as well as distinguish a first-order antisymmetric mode at 240 kHz at elevated temperatures up to 1000°C. The frequency characteristics of the signal were verified using a finite-element model and wavelet transformation analysis.}, number={5}, journal={IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control}, author={Johnson, J. A. and Kim, K. and Zhang, S. J. and Wu, D. and Jiang, X. N.}, year={2014}, pages={805–814} }
 @inproceedings{tolliver_jiang_xu_2014, title={Piezoelectric actuators with active and passive frames}, DOI={10.1115/smasis2013-3064}, abstractNote={Electromechanical actuators that generate large displacements, have large load capabilities, and demonstrate strong resonance characteristics are in great demand in the areas of precision positioning, active vibration control, and energy harvesting. Piezoelectric materials have been widely investigated for these applications because of their high energy density, quick response time, and relatively low driving voltages, but they demonstrate very small strain, typically about 0.1%. We present experimental and finite element results for two designs that use active and passive frames, respectively, to enhance the small strain in piezoelectric multilayer stacks. The first design, stacked-HYBATS, employs the synergetic contribution of d33 and d31 mode piezoelectric material. Finite element results show that this structure can generate over 50 microns of displacement and nearly 40 N of blocking force in a 36 mm × 22 mm × 10 mm footprint. The second design employs frames made from passive materials to form two stages of strain amplification in a 42 mm × 30 mm × 20 mm footprint. This two-stage design can produce over 600 microns of displacement and has a blocking force of 27 N. The active and passive materials of both designs can be varied to maximize displacement and/or blocking force. The stacked-HYBATS and the two-stage amplification system display favorable force-displacement capabilities and are promising for a variety of manufacturing and space technology applications.}, booktitle={Proceedings of the ASME Conference on Smart Materials, Adaptive Structures and Intelligent Systems - 2013, vol 1}, author={Tolliver, L. and Jiang, X. N. and Xu, T. B.}, year={2014} }
 @article{shu_li_huang_wei_yao_jiang_2014, title={Relationship between direct and converse flexoelectric coefficients}, volume={116}, ISSN={["1089-7550"]}, DOI={10.1063/1.4897647}, abstractNote={Flexoelectric effect, as a universal electromechanical coupling, has drawn lots of interests in dielectric materials. However, due to the restrictions of present measurement techniques, only part of coefficients has been experimentally examined. In this study, we derived the coordinate-dependent Gibbs free energy density function in the inhomogeneous spatial field to investigate the relationship between the direct and converse flexoelectric coefficients. In crystalline mediums and systems, the direct and converse flexoelectric coefficients are proved to equivalent according to the Maxwell relation. These results will broaden the application of the Maxwell relation into non-linear spatial field, and provide the guideline for experimental measurement and prediction of flexoelectric coefficients.}, number={14}, journal={JOURNAL OF APPLIED PHYSICS}, author={Shu, Longlong and Li, Fei and Huang, Wenbin and Wei, Xiaoyong and Yao, Xi and Jiang, Xiaoning}, year={2014}, month={Oct} }
 @article{guo_suo_jing_jiang_frank_lin_2014, title={Thrombolysis enhanced by dual-frequency high-intensity focused ultrasound}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0541}, abstractNote={It has been demonstrated that high-intensity focused ultrasound can be an efficient method to induce thrombolysis. Excessive thermal effect on neighboring tissue is however a concern. The goal of this work is to test the efficacy of dual-frequency ultrasound-induced thrombolysis, with the aim to reduce the acoustic power required to achieve the same lysis rate (mass loss of blood clots over time) as single-frequency ultrasound. In vitro clots of mouse blood were prepared and placed at the focus of two piezoelectric ultrasound transducers (center frequencies were 0.95 MHz and 1.5 MHz, respectively). 0.65 W ultrasound waves with 10% duty cycle were employed in both single- and dual-frequency ultrasound exposures. The mass losses of the clots were recorded to obtain the lysis rate after each test. It was found that dual-frequency results in more efficient thrombolysis. Cavitation bubble modeling was also conducted for both single- and dual-frequency ultrasound to explain the experimental founding.}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Guo, Sijia and Suo, Dingjie and Jing, Yun and Jiang, Xiaoning and Frank, Jonathan and Lin, Weili}, year={2014}, pages={2173–2176} }
 @article{di_price_gu_jiang_jing_gu_2014, title={Ultrasound-Triggered Regulation of Blood Glucose Levels Using Injectable Nano-Network}, volume={3}, ISSN={2192-2640}, url={http://dx.doi.org/10.1002/ADHM.201300490}, DOI={10.1002/ADHM.201300490}, abstractNote={The integration of an injectable insulin-encapsulated nano-network with a focused ultrasound system (FUS) can remotely regulate insulin release both in vitro and in vivo. A single subcutaneous injection of the nano-network with intermittent FUS administration facilitates reduction of the blood glucose levels in type 1 diabetic mice for up to 10 d.}, number={6}, journal={Advanced Healthcare Materials}, publisher={Wiley}, author={Di, Jin and Price, Jennifer and Gu, Xiao and Jiang, Xiaoning and Jing, Yun and Gu, Zhen}, year={2014}, month={Jun}, pages={811–816} }
 @article{yan_huang_kwon_yang_jiang_yuan_2013, title={A sensor for the direct measurement of curvature based on flexoelectricity}, volume={22}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/22/8/085016}, abstractNote={A direct curvature sensing measurement based on the flexoelectricity of Ba0.64Sr0.36TiO3 (BST) material through electromechanical coupling is proposed and developed in this paper. The curvature sensing was demonstrated in four point bending tests of a beam with bonded BST curvature sensors under different applied loads with low time-harmonic frequencies from 0.5 to 3 Hz. A shear lag concept which describes the efficiency of the loading transfer from the epoxy bonding layer was taken into account in extracting the actual curvature from the sensor measurement. A finite element analysis has been performed to estimate the curvature transfer efficiency and the bonding layer thickness is found to be a critical parameter in determining the curvature transfer. Experimental results showed a good linearity of charge output dependence on curvature inputs in a limited frequency range and showed a curvature sensitivity of 30.78 pC m, in comparison with 32.48 pC m from theoretical predictions. Using the measured curvature, the bending stiffness of the beam was then obtained from the experimentally obtained moment–curvature curve. This work demonstrated that the flexoelectric BST sensor provides a direct curvature measurement instead of using a traditional strain gage sensor through interpolation, and thus offers an important avenue for on-line and in situ structural health monitoring.}, number={8}, journal={SMART MATERIALS AND STRUCTURES}, author={Yan, Xiang and Huang, Wenbin and Kwon, Seol Ryung and Yang, Shaorui and Jiang, Xiaoning and Yuan, Fuh-Gwo}, year={2013}, month={Aug} }
 @article{xu_tolliver_jiang_su_2013, title={A single crystal lead magnesium niobate-lead titanate multilayer-stacked cryogenic flextensional actuator}, volume={102}, ISSN={["0003-6951"]}, DOI={10.1063/1.4790142}, abstractNote={A “33” mode single crystal lead magnesium niobate-lead titanate flextensional actuator with large displacement, high load capability, and broad bandwidth was designed, prototyped, and evaluated at temperatures ranging from room temperature to cryogenic temperatures. Measuring 27.4 × 10 × 13.6 mm (height) overall and weighing 9.2 g, the actuator generates a 96.5 μm displacement in the Z-direction at 170 Vrms. The level of displacement remained constant under compressive loads up to 5 kg force. The actuator maintains 66% of its room temperature displacement at −196 °C. The measured displacements matched well with those modeled using ANSYS finite element analysis.}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={Xu, Tian-Bing and Tolliver, Laura and Jiang, Xiaoning and Su, Ji}, year={2013}, month={Jan} }
 @article{yan_huang_kwon_yang_jiang_yuan_2013, title={Design of a curvature sensor using a flexoelectric material}, volume={8692}, ISSN={["1996-756X"]}, DOI={10.1117/12.2009941}, abstractNote={A curvature sensor based on flexoelectricity using Ba0.64Sr0.36TiO3 (BST) material is proposed and developed in this paper. The working principle of the sensor is based on the flexoelectricity, exhibiting coupling between mechanical strain gradient and electric polarization. A BST curvature sensor is lab prepared using a conventional solid state processing method. The curvature sensing is demonstrated in four point bending tests of the beam under harmonic loads. BST sensors are attached on both side surfaces of an aluminum beam, located symmetrically with respect to its neutral axis. Analyses have shown that the epoxy bonding layer plays a critical role for curvature transfer. Consequently a shear lag effect is taken into account for extracting actual curvature from the sensor measurement. Experimental results demonstrated good linearity from the charge outputs under the frequencies tests and showed a sensor sensitivity of 30.78pC•m in comparison with 32.48pC•m from theoretical prediction. The BST sensor provides a direct curvature measure instead of using traditional strain gage through interpolation and may offer an optional avenue for on-line and in-situ structural health monitoring.}, journal={SENSORS AND SMART STRUCTURES TECHNOLOGIES FOR CIVIL, MECHANICAL, AND AEROSPACE SYSTEMS 2013}, author={Yan, X. and Huang, W. B. and Kwon, S. R. and Yang, S. R. and Jiang, X. N. and Yuan, F. G.}, year={2013} }
 @article{ma_guo_wu_geng_jiang_2013, title={Design, Fabrication, and Characterization of a Single-Aperture 1.5-MHz/3-MHz Dual-Frequency HIFU Transducer}, volume={60}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2013.2724}, abstractNote={High-intensity focused ultrasound (HIFU) treatment efficiency is critical in maximizing the hyperthermia and reducing the surgery time. In this paper, a single-aperture, 1.5 MHz/3 MHz dual-frequency HIFU transducer was designed, fabricated, and characterized for tissue ablation enhancement. Double PZT-2 layers were configured in serial and dual-frequency ultrasound waves can be concurrently generated by exciting one of the PZT-2 layers. Impulse responses from the prototype showed that the wave amplitudes at 1.5 and 3 MHz were about the same, and both are more than 12 dB larger than those of higher orders of harmonics. Tissue ablation tests demonstrated that higher temperature rise can be achieved with dual-frequency ultrasound than with single-frequency ablation at the same acoustic power.}, number={7}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Ma, Jianguo and Guo, Sijia and Wu, Di and Geng, Xuecang and Jiang, Xiaoning}, year={2013}, month={Jul}, pages={1519–1529} }
 @article{wang_li_jiang_liu_geng_2013, title={Design, fabrication and characterization of a bi-frequency co-linear array (7.5MHz/15MHz)}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2013.0131}, abstractNote={Ultrasound imaging with high resolution and large field of depth is important in disease diagnosis, surgery guidance and post-surgery assessment. Conventional ultrasound imaging arrays work at a particular frequency, with -6dB fractional bandwidth of <; 100%, limiting the resolution or field of depth in many ultrasound imaging cases. This paper presented design of a 7.5 MHz / 15 MHz bi-frequency co-linear array prototype with a wide bandwidth of 5MHz-20 MHz, which can be significant in a broad range of biomedical ultrasound imaging applications. To demonstrate the concept, a 32-element 1-D linear sub-array was fabricated, followed by element characterization and beamforming tests using a Verasonics system. Beam steering at +/- 40 degree was achieved without obvious side lobes. The initial results suggest great potential of this bi-frequency co-linear array for medical imaging with high resolution and large field of depth.}, journal={2013 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Li, Sibo and Jiang, Xiaoning and Liu, Ruibin and Geng, Xuecang}, year={2013}, pages={504–507} }
 @article{ma_wang_jiang_2013, title={Design, fabrication and test of a small aperture, dual frequency ultrasound transducer}, volume={8695}, ISSN={["1996-756X"]}, DOI={10.1117/12.2009716}, abstractNote={High resolution ultrasound medical imaging requires high frequency transducers, which usually are known with decreased penetration depth because of high loss in two-way-loop at high frequencies. To obtain high resolution imaging at large depth, a dual frequency transducer was designed for contrast imaging. Specifically, a 35 MHz receiving transducer with aperture of 0.6 mm x 0.6 mm was integrated into a 6.5 MHz transmitting transducer with aperture of 0.6 mm x 3 mm. High pressure ultrasound at low frequency was generated by the transducer to excited microbubbles in tissue. High frequency component of the nonlinear response from microbubbles were received by the 35 MHz transducer for high resolution imaging at a relatively large depth. The prototyped transducer showed the ability of transmitting about 2 MPa pressure at 6.5 MHz, under an input of 5-cycle burst at 250 Vpp, which is high enough to generate nonlinear oscillation of microbubbles. The pulse-echo test showed that the -6 dB bandwidth of the 35 MHz transducer is 34.4% and the loop sensitivity is -38.3 dB. The small aperture, dual frequency ultrasound transducers developed in this paper are promising for high resolution ultrasound medical imaging.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS 2013}, author={Ma, Jianguo and Wang, Zhuochen and Jiang, Xiaoning}, year={2013} }
 @article{xu_siochi_kang_zuo_zhou_tang_jiang_2013, title={Energy harvesting using a PZT ceramic multilayer stack}, volume={22}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/22/6/065015}, abstractNote={In this paper, the interdisciplinary energy harvesting issues on piezoelectric energy harvesting were investigated using a ‘33’ mode (mechanical stress and/or electric field are in parallel to the polarization direction) lead zirconate titanate multilayer piezoelectric stack (PZT-Stack). Key energy harvesting characteristics including the generated electrical energy/power in the PZT-Stack, the mechanical to electrical energy conversion efficiency, the power delivered from the PZT-Stack to a resistive load, the electrical charge/energy transferred from the PZT-Stack to a super-capacitor were systematically addressed. Theoretical models for power generation and delivery to a resistive load were proposed and experimentally affirmed. In a quasi-static regime, 70% generated electrical powers were delivered to matched resistive loads. A 35% mechanical to electrical energy conversion efficiency, which is more than 4 times higher than other reports, for the PZT-Stack had been obtained. The generated electrical power and power density were significantly higher than those from a similar weight and size cantilever-type piezoelectric harvester in both resonance and off-resonance modes. In addition, our study indicated that the capacitance and piezoelectric coefficient of the PZT-Stack were strongly dependent on the dynamic stress.}, number={6}, journal={SMART MATERIALS AND STRUCTURES}, author={Xu, Tian-Bing and Siochi, Emilie J. and Kang, Jin Ho and Zuo, Lei and Zhou, Wanlu and Tang, Xiudong and Jiang, Xiaoning}, year={2013}, month={Jun} }
 @article{tolliver_xu_jiang_2013, title={Finite element analysis of the piezoelectric stacked-HYBATS transducer}, volume={22}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/22/3/035015}, abstractNote={Finite element modeling (FEM) of a piezoelectric multilayer-stacked hybrid actuation/transduction system (stacked-HYBATS) is investigated in this paper using ANSYS software. This transducer consists of two positive strain components operating in d33 mode and one negative strain component operating in d31 mode to generate large displacements. FEM results are compared with experimental and analytical results to provide insight into the actuation mechanisms, verify the device’s three displacement components, and estimate its blocking force. FEM calculations found the effective piezoelectric coefficient to be exceptional, about 3.11 × 106 pm V−1 at resonance. Stacked-HYBATS was quantitatively compared to commercially available flextensional actuators using finite element analysis. It was found that under the same electric field the yielded displacement of a stacked-HYBATS is about 200% and 15% larger than that of a same-sized d31 and d33 flextensional actuator, respectively. These findings suggest that stacked-HYBATS is promising for precision positioning, vibration control, and acoustic applications.}, number={3}, journal={SMART MATERIALS AND STRUCTURES}, author={Tolliver, Laura and Xu, Tian-Bing and Jiang, Xiaoning}, year={2013}, month={Mar} }
 @misc{jiang_huang_zhang_2013, title={Flexoelectric nano-generator: Materials, structures and devices}, volume={2}, ISSN={["2211-3282"]}, DOI={10.1016/j.nanoen.2013.09.001}, abstractNote={Flexoelectricity, as a fundamental electromechanical coupling effect between electric polarization and mechanical strain gradient, or vice versa between electric polarization gradient and mechanical gradient, exists in various categories of materials including solid materials, liquid crystals, polymers, and biomembranes. Dependence of electric or mechanical gradients on geometry requires the adoption of specific structures for different flexoelectric mode applications. Scaling effect associated with gradient suggests that flexoelectric effect can be more significant in micro/nano systems, comparable to or even exceed piezoelectricity. In this review, flexoelectricity in those studied materials will be summarized and compared. Applications in sensors, actuators, capability of tuning the ferroelectric thin film properties, and roles in bio-system mechanosensitivity and mechanotranduction of flexoelectricity will be introduced respectively. Especially, flexoelectricity nano-generator enlightens a new technique for energy harvesting. Comparison with piezoelectric nano-generator suggests that flexoelectric counterpart can yield enhanced performance with specific nanostructures and provide a wider materials choice.}, number={6}, journal={NANO ENERGY}, author={Jiang, Xiaoning and Huang, Wenbin and Zhang, Shujun}, year={2013}, month={Nov}, pages={1079–1092} }
 @article{kwon_huang_zhang_yuan_jiang_2013, title={Flexoelectric sensing using a multilayered barium strontium titanate structure}, volume={22}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/22/11/115017}, abstractNote={The flexoelectric effect has been recently explored for its promise in electromechanical sensing. However, the relatively low flexoelectric coefficients of ferroelectrics inhibit the potential to develop flexoelectric sensing devices. In this paper, a multilayered structure using flexoelectric barium strontium titanate (Ba0.65Sr0.35TiO3 or BST) ceramic was fabricated in an attempt to enhance the effective flexoelectric coefficients using its inherent scale effect, and hence to improve the flexoelectric sensitivity. The performances of piezoelectric and flexoelectric cantilevers with the same dimensions and under the same conditions were compared. Owing to the flexoelectric scaling effect, under the same force input, the BST flexoelectric structure generated a higher charge output than its piezoelectric P(VDF-TrFE) and PMN-30PT counterparts when its thickness was less than 73.1 μm and 1.43 μm, respectively. Also, amplification of the charge output using the multilayered structure was then experimentally verified. The prototyped structure consisted of three layers of 350 μm-thick BST plates with a parallel electric connection. The charge output was approximately 287% of that obtained using a single-layer structure with the same total thickness of the multilayered structure under the same end deflection input, which suggests high sensitivity sensing can be achieved using multilayer flexoelectric structures.}, number={11}, journal={SMART MATERIALS AND STRUCTURES}, author={Kwon, S. R. and Huang, W. B. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N.}, year={2013}, month={Nov} }
 @article{johnson_kim_zhang_wu_jiang_2013, title={High-temperature (> 1000 degrees C) acoustic emission sensor}, volume={8694}, ISSN={["1996-756X"]}, DOI={10.1117/12.2009301}, abstractNote={Piezoelectric crystals have shown promising results as acoustic emission sensors, but are often hindered by the loss of electric properties above temperatures in the 500-700°C range. Yttrium calcium oxyborate, (YCOB), however, is a promising high temperature piezoelectric material due to its high resistivity at high temperatures and its relatively stable electromechanical and piezoelectric properties across a broad temperature range. In this paper, a piezoelectric acoustic emission sensor was designed, fabricated, and tested for use in high temperature applications using a YCOB single crystal. An acoustic wave was generated by a Hsu-Nielsen source on a stainless steel bar, which then propagated through the substrate into a furnace where the YCOB acoustic emission sensor is located. Charge output of the YCOB sensor was collected using a lock-in charge amplifier. The sensitivity of the YCOB sensor was found to have small to no degradation with increasing temperature up to 1000 °C. This oxyborate crystal showed the ability to detect zero order symmetric and antisymmetric modes, as well as distinguishable first order antisymmetric modes at elevated temperatures up to 1000 °C.}, journal={NONDESTRUCTIVE CHARACTERIZATION FOR COMPOSITE MATERIALS, AEROSPACE ENGINEERING, CIVIL INFRASTRUCTURE, AND HOMELAND SECURITY 2013}, author={Johnson, Joseph A. and Kim, Kyungrim and Zhang, Shujun and Wu, Di and Jiang, Xiaoning}, year={2013} }
 @article{chang_huang_bagal_chang_tian_han_jiang_2013, title={Study on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O-3-0.3 PbTiO3 single crystal with nano-patterned composite electrode}, volume={114}, ISSN={["1089-7550"]}, DOI={10.1063/1.4821517}, abstractNote={Effect of nano-patterned composite electrode and backswitching poling technique on dielectric and piezoelectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 was studied in this paper. Composite electrode consists of Mn nano-patterns with pitch size of 200 nm, and a blanket layer of Ti/Au was fabricated using a nanolithography based lift-off process, heat treatment, and metal film sputtering. Composite electrode and backswitching poling resulted in 27% increase of d33 and 25% increase of dielectric constant, and we believe that this is attributed to regularly defined nano-domains and irreversible rhombohedral to monoclinic phase transition in crystal. The results indicate that nano-patterned composite electrode and backswitching poling has a great potential in domain engineering of relaxor single crystals for advanced devices.}, number={11}, journal={JOURNAL OF APPLIED PHYSICS}, author={Chang, Wei-Yi and Huang, Wenbin and Bagal, Abhijeet and Chang, Chih-Hao and Tian, Jian and Han, Pengdi and Jiang, Xiaoning}, year={2013}, month={Sep} }
 @article{guo_jing_jiang_2013, title={Temperature Rise in Tissue Ablation Using Multi-Frequency Ultrasound}, volume={60}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2013.2751}, abstractNote={High-intensity focused ultrasound (HIFU) is becoming an increasingly important noninvasive surgical tool, despite the challenges in temperature rise control and unwanted heating problems. In this study, experiments and simulations on tissue ablation effectiveness were performed using multi-frequency HIFU with frequency differences of more than 500 kHz (center frequencies are 950 kHz, 1.5 MHz, and 3.3 MHz). In the experiments, the temperature was recorded as chicken breast tissue was heated by single-frequency, dual-frequency, and tri-frequency HIFU configurations at controlled acoustic power and exposure time. 5% to 10% temperature rise differences were observed between single- and multi-frequency modes, indicating that multi-frequency HIFU is more effective at producing faster temperature rises. Cavitation detection tests were conducted to compare the cavitation pressure fields between single- and multi-frequency ultrasound. Moreover, simulations on single-frequency and multi-frequency acoustic fields as well as bio-heating-induced temperature fields were performed. With the comparison between experimental and simulation results, we believe that the more effective tissue ablation using multi-frequency ultrasound is likely attributed to the enhanced cavitation, a promising result for HIFU applications.}, number={8}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Guo, Sijia and Jing, Yun and Jiang, Xiaoning}, year={2013}, month={Aug}, pages={1699–1707} }
 @article{kim_jiang_2013, title={Tissue characterization using an acoustic wave tactile sensor array}, volume={8695}, ISSN={["1996-756X"]}, DOI={10.1117/12.2009518}, abstractNote={Tactile perception of different types of tissue is important in order for surgeons to perform procedures correctly and safely. This is especially true in minimally invasive surgery (MIS) where the surgeon must be able to locate the target tissue without a direct line of sight or direct finger touch. In this study, tissue characterization using an acoustic wave tactile sensor array was investigated. This type of tactile sensor array can detect the acoustic impedance change of target materials. Abnormal tissues can have different Young’s moduli and shear moduli caused by composition change compared to those of healthy tissues. This also leads to a difference in acoustic impedance which can be detected using our sensor array. The array was fabricated using a face-shear mode PMN-PT piezoelectric resonator which is highly sensitive to acoustic impedance load. Gelatin and water mixtures with weight concentration of 5 wt % - 30 wt % were prepared as tissue phantoms. The shear modulus of each phantom was measured using bulk face-shear mode crystal resonators, and it was found that shear modulus change from 120 kPa to 430 kPa resulted on 30 % electrical impedance shift from the resonator. Imaging display of elastic properties of prepared phantoms was also tested using the fabricated sensor array. The proposed tissue characterization technique is promising for the development of effective surgical procedures in minimally invasive surgery.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS 2013}, author={Kim, Kyungrim and Jiang, Xiaoning}, year={2013} }
 @article{kim_zhang_salazar_jiang_2012, title={Design, fabrication and characterization of high temperature piezoelectric vibration sensor using YCOB crystals}, volume={178}, ISSN={["0924-4247"]}, DOI={10.1016/j.sna.2012.02.003}, abstractNote={A shear-mode piezoelectric accelerometer using YCa4O(BO3)3 single crystals (YCOB) was designed, fabricated and successfully tested for high temperature vibration sensing applications. Dynamic modeling of the accelerometer was presented first, followed by YCOB single crystal sample preparation, sensor assembly and experimental setup establishment. The prototyped accelerometer was tested at temperatures ranging from room temperature to 1000 °C and at frequencies ranging from 50 Hz to 350 Hz. The sensitivity of the prototype was found to be 5.9 ± 0.06 pC/g throughout the tested frequency, temperature and acceleration ranges. In addition, YCOB piezoelectric accelerometers retained the same sensitivity at 1000 °C for a dwell time of 9 h, exhibiting a high stability and reliability.}, journal={SENSORS AND ACTUATORS A-PHYSICAL}, author={Kim, Kyungrim and Zhang, Shujun and Salazar, Giovanni and Jiang, Xiaoning}, year={2012}, month={May}, pages={40–48} }
 @article{kim_zhang_tian_han_jiang_2012, title={Face-shear Mode Ultrasonic Tactile Sensor Array}, ISBN={["978-1-4673-4561-3"]}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2012.0265}, abstractNote={Ultrasonic sensors using piezoelectric resonators are widely used for the chemical and biomedical applications because of their high sensitivity to applied loads, simple structures, and relatively low cost. In this study, we investigated an ultrasonic tactile sensing array using face-shear mode PMN-PT single crystal resonators, based on the sensing mechanism that electric impedance of a piezoelectric resonator is dependent on its surface acoustic load. An 8 × 8 sensing array was designed, fabricated and characterized. The electrical impedance changes induced by the applied surface loads including acoustic loads and surface forces were measured, and then, the contact shape of applied object was mapped by recording electric impedances of 64 elements.}, journal={2012 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Kim, Kyungrim and Zhang, Shujun and Tian, Jian and Han, Pengdi and Jiang, Xiaoning}, year={2012}, pages={1059–1062} }
 @inproceedings{huang_kim_zhang_yuan_jiang_2012, title={Flexoelectric materials and structures for M/NEMS}, DOI={10.1115/imece2011-64520}, abstractNote={Recent research progress on flexoelectricity suggests that dramatic enhancement of effective piezoelectric properties desirable for advanced M/NEMS, in principle, is attainable through flexoelectric (FE) effect and scale effect. In this paper, the transverse flexoelectric coefficient μ12 of barium strontium titanate (BST) microcantilevers with thicknesses ranging from 1.4 mm down to 30 μm was measured at room temperature. It was found that μ12 remains to be constant (8.5 μC/m) for all fabricated microcantilevers. Effective piezoelectric coefficients of these microcantilevers were also calculated, indicating that significantly increased effective piezoelectric coefficients can be obtained from microcantilevers with thickness of microns and nanometers, which is promising for micro/nano electromechanical systems (M/NEMS).}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2011, vol 11}, author={Huang, W. B. and Kim, K. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N.}, year={2012}, pages={761–766} }
 @article{huang_yan_kwon_zhang_yuan_jiang_2012, title={Flexoelectric strain gradient detection using Ba0.64Sr0.36TiO3 for sensing}, volume={101}, ISSN={["0003-6951"]}, DOI={10.1063/1.4772803}, abstractNote={Strain gradient sensing offers an alternative avenue for in-situ monitoring of onset and growth of cracks in structural health monitoring, where the strain gradient is the most sensitive measurand. In this study, flexoelectric strain gradient sensing structures using Ba0.64Sr0.36TiO3 (BST) were attached on the proximity of an open hole in an aluminum plate, to monitor strain gradient variations of the specimen under a uniaxial dynamic load. Charge outputs of the BST micro-bars showed good linearity with the average strain gradients, with a sensitivity of 88 pC m, which is in good agreement with the theoretical estimation by assuming a 30 μm bonding thickness.}, number={25}, journal={APPLIED PHYSICS LETTERS}, author={Huang, Wenbin and Yan, Xiang and Kwon, Seol Ryung and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2012}, month={Dec} }
 @inproceedings{bakshi_guo_jiang_2012, title={Multi-frequency focused ultrasound for tissue ablation}, DOI={10.1115/imece2011-64076}, abstractNote={In this study, the effectiveness of tissue ablation was investigated using multi-frequency high intensity focused ultrasound (HIFU) transducers (950 kHz, 1.5 MHz). Temperature rise and lesion volume were recorded when chicken tissue was ablated by focused ultrasound (FUS) with controlled ultrasound power and exposure time using single frequency and multi-frequency modes. It was found that multi-frequency tissue ablation gives a higher maximum temperature accompanied by a faster rise, and a larger ablation lesion volume, compared with single frequency ablation, under the same input conditions of electrical power, exposure time and depth of focus. Also, it was concluded that the same desired tissue temperature and ablation lesion conditions can be attained by using less power for the multi-frequency ablation. These findings are promising because the multi-frequency ultrasound ablation using FUS with a greater frequency difference could result in promising imaging guided effective therapy using one multi-frequency probe.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, vol 2}, author={Bakshi, S. and Guo, S. J. and Jiang, X. N.}, year={2012}, pages={665–670} }
 @article{kim_zhang_jiang_2012, title={Surface Acoustic Load Sensing Using a Face-Shear PIN-PMN-PT Single-Crystal Resonator}, volume={59}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2012.2488}, abstractNote={Pb(In0.5Nb0.5)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) resonators for surface acoustic load sensing are presented in this paper. Different acoustic loads are applied to thickness mode, thickness-shear mode, and face-shear mode resonators, and the electrical impedances at resonance and anti-resonance frequencies are recorded. More than one order of magnitude higher sensitivity (ratio of electrical impedance change to surface acoustic impedance change) at the resonance is achieved for the face-shear-mode resonator compared with other resonators with the same dimensions. The Krimholtz, Leedom, and Matthaei (KLM) model is used to verify the surface acoustic loading effect on the electrical impedance spectrum of face-shear PIN-PMN-PT single-crystal resonators. The demonstrated high sensitivity of face-shear mode resonators to surface loads is promising for a broad range of applications, including artificial skin, biological and chemical sensors, touch screens, and other touch-based sensors.}, number={11}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Kim, Kyungrim and Zhang, Shujun and Jiang, Xiaoning}, year={2012}, month={Nov}, pages={2548–2554} }
 @article{kim_zhang_jiang_2012, title={Surface load induced electrical impedance shift in relaxor-PbTiO3 crystal piezoelectric resonators}, volume={100}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4729766}, DOI={10.1063/1.4729766}, abstractNote={The effect of surface loads on Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal piezoelectric resonators was studied. Electrical impedance shifts at both resonance and anti-resonance frequencies due to surface loads were recorded for comparison among face-shear mode, thickness-shear mode, and thickness mode resonators. It was observed that electrical impedances of face shear mode resonators exhibited significantly higher sensitivity to surface load changes comparing with other resonators with similar dimensions, because of enhanced energy dissipation in face shear mode resonators, indicating a promising innovative face-shear mode single crystal piezoelectric sensing mechanism.}, number={25}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Kim, Kyungrim and Zhang, Shujun and Jiang, Xiaoning}, year={2012}, month={Jun}, pages={253501} }
 @article{guo_wang_allbritton_jiang_2012, title={Ultrasound-induced release of micropallets with cells}, volume={101}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4757648}, DOI={10.1063/1.4757648}, abstractNote={Separation of selected adherent live cells attached on an array of microelements, termed micropallets, from a mixed population is an important process in biomedical research. We demonstrated that adherent cells can be safely, selectively, and rapidly released from the glass substrate together with micropallets using an ultrasound wave. A 3.3-MHz ultrasound transducer was used to release micropallets (500 μm × 500 μm × 300 μm) with attached HeLa cells, and a cell viability of 92% was obtained after ultrasound release. The ultrasound-induced release process was recorded by a high-speed camera, revealing a proximate velocity of ∼0.5 m/s.}, number={16}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Guo, Sijia and Wang, Yuli and Allbritton, Nancy and Jiang, Xiaoning}, year={2012}, month={Oct}, pages={163703} }
 @article{kim_jiang_zhang_2011, title={A High Temperature Piezoelectric Sensor for Structure Health Monitoring}, volume={7983}, ISSN={["1996-756X"]}, DOI={10.1117/12.880163}, abstractNote={High temperature sensors play a significant role in aerospace, automotive and energy industries. In this paper, a shearmode piezoelectric accelerometer using YCa4O(BO3)3 single crystals (YCOB) was designed and fabricated for high temperature sensing applications. The prototype sensor was tested at the temperature ranging from room temperature to 1000°C. The sensitivity of the sensor was found to be 1.9±04 pC/g throughout the tested frequency and temperature range. Moreover, YCOB piezoelectric accelerometers remained stable performance at 1000°C for a dwell time of three hours.}, journal={NONDESTRUCTIVE CHARACTERIZATION FOR COMPOSITE MATERIALS, AEROSPACE ENGINEERING, CIVIL INFRASTRUCTURE, AND HOMELAND SECURITY 2011}, author={Kim, Kyungrim and Jiang, Xiaoning and Zhang, Shujun}, year={2011} }
 @article{xu_jiang_su_2011, title={A piezoelectric multilayer-stacked hybrid actuation/transduction system}, volume={98}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3600057}, DOI={10.1063/1.3600057}, abstractNote={A piezoelectric multilayer-stacked hybrid actuation/transduction system (stacked-HYBATS) is reported in this letter. It uses synergetic contributions from positive-strain and negative-strain piezoelectric multilayer-stacks to give displacements of about 3.5 times those of the same-sized piezoelectric flextensional actuator/transducer. The resonance of a stacked-HYBATS is enhanced comparing with that of actuators with either stack alone. The effective piezoelectric coefficient of the stacked-HYBATS is 2.5×106 pm/V at the resonance frequency and 1.5×105 pm/V at off-resonance frequencies. The stacked-HYBATS provides an approach for high performance electromechanical devices.}, number={24}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Xu, Tian-Bing and Jiang, Xiaoning and Su, Ji}, year={2011}, month={Jun}, pages={243503} }
 @article{huang_kim_zhang_yuan_jiang_2011, title={Scaling effect of flexoelectric (Ba,Sr)TiO3 microcantilevers}, volume={5}, ISSN={["1862-6254"]}, DOI={10.1002/pssr.201105326}, abstractNote={Abstract}, number={9}, journal={PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS}, author={Huang, Wenbin and Kim, Kyungrim and Zhang, Shujun and Yuan, Fuh-Gwo and Jiang, Xiaoning}, year={2011}, month={Sep}, pages={350–352} }
 @article{thein_cheng_khanna_zhang_park_ahmed_goodrich_asphahani_wu_smith_et al._2011, title={Site-specific sonoporation of human melanoma cells at the cellular level using high lateral-resolution ultrasonic micro-transducer arrays}, volume={27}, ISSN={["0956-5663"]}, DOI={10.1016/j.bios.2011.05.026}, abstractNote={We developed a new instrumental method by which human melanoma cells (LU1205) are sonoporated via radiation pressures exerted by highly-confined ultrasonic waves produced by high lateral-resolution ultrasonic micro-transducer arrays (UMTAs). The method enables cellular-level site-specific sonoporation within the cell monolayer due to UMTAs and can be applicable in the delivery of drugs and gene products in cellular assays. In this method, cells are seeded on the biochip that employs UMTAs for high spatial resolution and specificity. UMTAs are driven by 30-MHz sinusoidal signals and the resulting radiation pressures induce sonoporation in the targeted cells. The sonoporation degree and the effective lateral resolution of UMTAs are determined by performing fluorescent microscopy and analysis of carboxylic-acid-derivatized CdSe/ZnS quantum dots passively transported into the cells. Models representing the transducer-generated ultrasound radiation pressure, the ultrasound-inflicted cell membrane wound, and the transmembrane transport through the wound are developed to determine the ultrasound-pressure-dependent wound size and enhanced cellular uptake of nanoparticles. Model-based calculations show that the effective wound size and cellular uptake of nanoparticles increase linearly with increasing ultrasound pressure (i.e., at applied radiation pressures of 0.21, 0.29, and 0.40 MPa, the ultrasound-induced initial effective wound radii are 150, 460, and 650 nm, respectively, and the post-sonoporation intracellular quantum-dot concentrations are 7.8, 22.8, and 29.9 nM, respectively) and the threshold pressure required to induce sonoporation in LU1205 cells is ∼0.12 MPa.}, number={1}, journal={BIOSENSORS & BIOELECTRONICS}, author={Thein, Myo and Cheng, An and Khanna, Payal and Zhang, Chunfeng and Park, Eun-Joo and Ahmed, Daniel and Goodrich, Christopher J. and Asphahani, Fareid and Wu, Fengbing and Smith, Nadine B. and et al.}, year={2011}, month={Sep}, pages={25–33} }
 @article{ting-feng_chao_xiao-ning_guan-ping_2011, title={Thickness shear mode quartz crystal resonators with optimized elliptical electrodes}, volume={20}, ISSN={["1674-1056"]}, DOI={10.1088/1674-1056/20/4/047701}, abstractNote={Quartz crystal resonators (QCRs) with circular electrodes have been widely used for various liquid and gas sensing applications. In this work, quartz crystal resonators with elliptical electrodes were studied and tested for liquid property measurement. Mindlin's theory was used to optimize the dimension and geometry of the electrodes and a 5-MHz QCR with minimum series resistance and without any spurious modes was obtained. A series of AT-cut QCRs with elliptical electrodes of different sizes were fabricated and their sensing performances were compared to devices with circular electrodes. The experimental result shows that the device with elliptical electrodes can obtain lower resonance impedance and a higher Q factor, which results in a better loading capability. Even though the sensitivities of devices with elliptical and circular electrodes are found to be similar, the sensor with elliptical electrodes has much higher resolution due to a better frequency stability. The study indicates that the performance of QCRs with elliptical electrodes is superior to that of traditional QCRs with circular electrodes.}, number={4}, journal={CHINESE PHYSICS B}, author={Ting-Feng, Ma and Chao, Zhang and Xiao-Ning, Jiang and Guan-Ping, Feng}, year={2011}, month={Apr} }
 @article{kim_zhang_huang_yu_jiang_2011, title={YCa4O(BO3)(3) (YCOB) high temperature vibration sensor}, volume={109}, ISSN={["1089-7550"]}, DOI={10.1063/1.3598115}, abstractNote={A shear-mode piezoelectric accelerometer using YCa4O(BO3)3 (YCOB) single crystal was designed, fabricated and successfully tested for high temperature vibration sensing applications. The prototyped sensor was tested at temperatures ranging from room temperature to 1000 °C and at frequencies ranging from 80 Hz to 1 kHz. The sensitivity of the sensor was found to be 5.7 pC/g throughout the tested frequency and temperature range. In addition, YCOB piezoelectric accelerometers remained the same sensitivity at 1000 °C for a dwell time of four hours, exhibiting high stability and reliability.}, number={12}, journal={JOURNAL OF APPLIED PHYSICS}, author={Kim, Kyungrim and Zhang, Shujun and Huang, Wenbin and Yu, Fapeng and Jiang, Xiaoning}, year={2011}, month={Jun} }
 @article{jiang_snook_liu_geng_hackenberger_2010, title={Fabrication and Characterization of High Frequency Phased Arrays for NDE Imaging}, volume={7649}, ISSN={["1996-756X"]}, DOI={10.1117/12.847624}, abstractNote={PMN-PT single crystal 1-3 composite high frequency phased arrays with center frequency of 35 MHz were fabricated and characterized for silicon carbide (SiC) NDE imaging applications. The 35 MHz 64-element array was successfully prototyped using PMN-PT single crystal and PC-MUT technology. The broad bandwidth > 90% and high sensitivity (echo amplitude > 500 mV from the impulse response with 0 gain) was observed with reasonably high uniformity. These high frequency phased arrays are promising for ceramic NDE imaging.}, journal={NONDESTRUCTIVE CHARACTERIZATION FOR COMPOSITE MATERIALS, AEROSPACE ENGINEERING, CIVIL INFRASTRUCTURE, AND HOMELAND SECURITY 2010}, author={Jiang, Xiaoning and Snook, Kevin and Liu, Ruibin and Geng, Xuecang and Hackenberger, Wesley S.}, year={2010} }
 @article{ma_zhang_feng_jiang_2010, title={Lateral field excitation properties of langasite single crystal}, volume={19}, DOI={10.1088/1674-1056/19/8/087701}, abstractNote={In this work, bulk acoustic wave propagation properties of langasite single crystal excited by lateral electric field have been investigated. Three important crystal cuts have been identified for different operational modes of lateral field excitation (LFE) on langasite substrate, namely the (yxl)65° (pure-LFE mode), (yxl)45° (quasi-LFE mode), and (yxl)0° (pseudo-LFE mode). Devices on langasite substrate with the above cuts were fabricated and tested, and the experimental results agree well with the theoretical analysis. It is found that a pure thickness shear mode exists in the (yxl)65° langasite LFE device with the bare side facing liquid, and no spurious mode is found due to its moderately large piezoelectric coupling factor. In addition, (yxl)0° langasite LFE device is also found suitable for liquid phase sensing applications.}, number={8}, journal={Chinese Physics. B, (Beijing, China)}, author={Ma, T. F. and Zhang, C. and Feng, G. P. and Jiang, X. N.}, year={2010} }
 @article{zhang_jiang_lapsley_moses_shrout_2010, title={Piezoelectric accelerometers for ultrahigh temperature application}, volume={96}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3290251}, DOI={10.1063/1.3290251}, abstractNote={High temperature sensors are of major importance to aerospace and energy related industries. In this letter, a high temperature monolithic compression-mode piezoelectric accelerometer was fabricated using YCa4O(BO3)3 (YCOB) single crystals. The performance of the sensor was tested as function of temperature up to 1000 °C and over a frequency range of 100–600 Hz. The accelerometer prototype was found to possess sensitivity of 2.4±0.4 pC/g, across the measured temperature and frequency range, indicating a low temperature coefficient. Furthermore, the sensor exhibited good stability over an extended dwell time at 900 °C, demonstrating that YCOB piezoelectric accelerometers are promising candidates for high temperature sensing applications.}, number={1}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Zhang, Shujun and Jiang, Xiaoning and Lapsley, Michael and Moses, Paul and Shrout, Thomas R.}, year={2010}, month={Jan}, pages={013506} }
 @article{dong_yan_viehland_jiang_hackenberger_2008, title={A piezoelectric single crystal traveling wave step motor for low-temperature application}, volume={92}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2908963}, DOI={10.1063/1.2908963}, abstractNote={A piezoelectric Pb(Mg1∕3Nb2∕3)O3-PbTiO3 single crystal traveling wave rotary motor operated in a stepping motion for cryogenic actuations was developed and characterized. This single crystal stepping motor had a torque of ⩾1.5kgcm, an excess of 1800 steps per revolution about its axis, and a power consumption of ≦2W by using a step motion with 25% duty cycle. We then show that this single crystal motor can successfully operate at 77K (liquid nitrogen) under a load.}, number={15}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Dong, Shuxiang and Yan, Li and Viehland, D. and Jiang, Xiaoning and Hackenberger, Wesley S.}, year={2008}, month={Apr}, pages={153504} }
 @article{zhang_fei_chai_frantz_snyder_jiang_shrout_2008, title={Characterization of piezoelectric single crystal YCa4O(BO3)3 for high temperature applications}, volume={92}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2936276}, DOI={10.1063/1.2936276}, abstractNote={Operation at temperatures well above ambient is desired for applications such as smart structures integrated within aircraft and space vehicles. Piezoelectric yttrium calcium oxyborate single crystal YCa4O(BO3)3 (YCOB) was found to exhibit no phase transition until its melting temperature around ∼1500°C. The temperature characteristics of the resonance frequency, electromechanical coupling, and dielectric permittivity were studied in the temperature range of 30–950°C for different orientations. The electrical resistivity at 800°C was found to be greater than 2×108Ωcm. Together with its temperature independent electromechanical coupling factor (∼12%) and engineered resonance frequency behavior, these make YCOB crystals excellent candidates for sensing applications at ultra high temperatures.}, number={20}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Zhang, Shujun and Fei, Yiting and Chai, Bruce H. T. and Frantz, Eric and Snyder, David W. and Jiang, Xiaoning and Shrout, Thomas R.}, year={2008}, month={May}, pages={202905} }
 @article{shcheglov_jiang_toda_chang_yang_2008, title={Hybrid linear microactuators and their control models for mirror shape correction}, volume={4}, ISSN={1865-3928 1865-3936}, url={http://dx.doi.org/10.1007/S12213-009-0017-2}, DOI={10.1007/S12213-009-0017-2}, abstractNote={Future space-based imaging systems demand ultra-lightweight mirrors, which would involve a large number of actuators to provide the needed surface correction. These lightweight actuators are required to be integrated with the mirrors to avoid a significant increase in overall areal mass density. This paper presents the fabrication and testing of a linear microactuator and the modeling of an actuated mirror composed of such lightweight actuators. The linear microactuator is driven by a combination of a piezoelectric actuator block and electrostatic comb drive units. A full nonlinear optimization model of a mirror lattice was developed to simulate a lightweight primary with embedded microactuators, which allows for an arbitrarily connected lattice with connector elements having an arbitrary stiffness and actuation response. The modeling yielded a high precision estimation of the mirror shape correction.}, number={4}, journal={Journal of Micro-Nano Mechatronics}, publisher={Springer Science and Business Media LLC}, author={Shcheglov, Kirill and Jiang, Xiaoning and Toda, Risaku and Chang, Zensheu and Yang, Eui-Hyeok}, year={2008}, month={Dec}, pages={159–167} }
 @article{dong_yan_wang_viehland_jiang_rehrig_hackenberger_2005, title={A small, linear, piezoelectric ultrasonic cryomotor}, volume={86}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1855424}, DOI={10.1063/1.1855424}, abstractNote={A small, linear-type, piezoelectric ultrasonic cryomotor has been developed for precision positioning at extremely low temperatures (⩾−200°C). This cryomotor consists of a pair of Pb(Mg1∕3Nb2∕3)O3−PbTiO3 single crystal stacks, which are piezoelectrically excited into the rotating third-bending mode of the cryomotor stator’s center, which in turn drives a contacted slider into linear motion via frictional forces. The performance characteristics achieved by the cryomotor are: (i) a maximum linear speed of >50mm∕s; (ii) a stroke of >10mm; (iii) a driving force of >0.2N; (iv) a response time of ∼29ms; and (v) a step resolution of ∼20nm.}, number={5}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Dong, Shuxiang and Yan, Li and Wang, Naigang and Viehland, Dwight and Jiang, Xiaoning and Rehrig, Paul and Hackenberger, Wes}, year={2005}, month={Jan}, pages={053501} }
 @article{woody_smith_jiang_rehrig_2005, title={Performance of single-crystal Pb(Mg1∕3Nb2∕3)-32%PbTiO3 stacked actuators with application to adaptive structures}, volume={76}, ISSN={0034-6748 1089-7623}, url={http://dx.doi.org/10.1063/1.1984974}, DOI={10.1063/1.1984974}, abstractNote={This article presents the performance of ultra-high-strain single-crystal piezoelectric stacked actuators using the composition Pb(Mg1∕3Nb2∕3)-32%PbTiO3 (PMN-32%PT)for adaptive structures (in particular for space-based applications). Generally, dimensionally adaptive or smart structures often utilize piezoelectric actuators [in particular lead zirconate titanate (PZT) elements] to provide high-frequency response motion. However, most commercial stacks are limited in range (often <0.1% strain) and the motion is further reduced at low or cryogenic temperatures for satellite-based and many other applications. Comparatively, single-crystal actuators such as the ultra-high-strain PMN-32%PT provide greater than a factor of 4 displacement, factor of 2 strain energy density, and cryogenic displacements are comparable to room-temperature conditions for PZT actuators. Nonetheless, there are some technological and fundamental limitations, such as plate thickness, which is generally greater than 0.5mm, low elastic modulus, and low strain at each end of the stacks. Three stack configurations with 3, 5, and 40 active layers are tested and discussed. This report discusses each configuration type as a function of lost motion, obtainable strain rates, preload designs, applied stiffness, stress gradients, electric fields, and bandwidth performances. The results obtained in this study aim to show performance and discuss the relative merits and limitations of using this actuator material for adaptive structures. A case study is presented for a high bandwidth steering mirror using ultra-high-strain single crystals. Closed loop control results from the platform’s response are briefly discussed.}, number={7}, journal={Review of Scientific Instruments}, publisher={AIP Publishing}, author={Woody, Shane C. and Smith, Stuart T. and Jiang, Xiaoning and Rehrig, Paul W.}, year={2005}, month={Jul}, pages={075112} }
 @article{zhan_wu_yin_jiang_2005, title={Strong, high-frequency, ac electric-field-induced rhombohedra-tetragonal phase transition in Pb(Mg1∕3Nb2∕3)O3–PbTiO3 single crystal}, volume={97}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.1881794}, DOI={10.1063/1.1881794}, abstractNote={Dielectric properties of Pb(Mg1∕3Nb2∕3)O3–PbTiO3 single crystals grown by a modified Bridgman method are investigated under strong, high-frequency (>100kHz) ac field. It is found that there is a phase transition due to the applied ac field, which may be due to the following reasons: (1) strong ac field periodically moves domains at fast speed that heats up the crystal due to the friction of domain change; and (2) phase transition happens because of the increase of the temperature. Compared with conventional heating techniques, ac field-induced phase transition is a quicker and more effective way. In addition, it is also found that continuous ac excitation can make the phase transition easier that may be due to the deaging effect caused by continuous ac excitation. Experimental results confirm the increase of d33 and the change of transmittance under strong ac field, which further verifies that phase transition indeed happens.}, number={7}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Zhan, Chun and Wu, Juntao and Yin, Shizhuo and Jiang, Xiaoning}, year={2005}, month={Apr}, pages={074107} }
 @inproceedings{li_huang_jiang_jian_cui, title={A dual-layer micromachined PMN-PT 1-3 composite transducer for broadband ultrasound imaging}, booktitle={2013 ieee international ultrasonics symposium (ius)}, author={Li, S. B. and Huang, W. B. and Jiang, X. N. and Jian, X. H. and Cui, Y. Y.}, pages={773–776} }
 @article{xu_jiang_su, title={A piezoelectric multilayer-stacked hybrid actuation/transduction system}, volume={98}, number={24}, journal={Applied Physics Letters}, author={Xu, T. B. and Jiang, X. N. and Su, J.} }
 @misc{jiang_kim_kim, title={Relaxor-PT single crystal piezoelectric sensors}, volume={4}, number={3}, journal={Crystals}, author={Jiang, X. N. and Kim, J. and Kim, K.}, pages={351–376} }
 @inproceedings{ma_jiang_martin_dayton, title={Small aperture, dual frequency ultrasound transducers for intravascular contrast imaging}, booktitle={2013 ieee international ultrasonics symposium (ius)}, author={Ma, J. G. and Jiang, X. N. and Martin, K. H. and Dayton, P. A.}, pages={761–764} }