@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{kim_zhang_wang_wu_xu_liu_moon_yamashita_ryu_liu_et al._2024, title={Electrical de-poling and re-poling of relaxor-PbTiO<sub>3</sub> piezoelectric single crystals without heat treatment}, volume={15}, ISSN={["2041-1723"]}, url={https://doi.org/10.1038/s41467-024-50847-3}, DOI={10.1038/s41467-024-50847-3}, abstractNote={Re-poling of unexpected partially depoled piezoelectric materials conventionally needs to be first fully depoled through annealing above their Curie temperature to revive piezoelectric performances. Here, we investigated de-poling and re-poling of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals under electric fields at room temperature. We found that alternating current electric fields with amplitudes near the coercive field at low frequencies (<10 Hz) can be employed to successfully depolarize poled crystals at room temperature. We also demonstrated a reversible polarization switching process with a relaxor-PbTiO3 single crystal ultrasound transducer without device performance degradations. This experimental observation is supported by phase-field simulation, showing that alternating current electric fields can readily induce de-poling at room temperature, while direct current electric fields induce a transient depoled state only within an uncontrollable short period of time. The findings suggest new strategies for unprecedented in-device tailoring of the polarization states of ferroelectric materials. The authors find that alternating current electric fields with amplitudes near the coercive field at low frequencies (<10 Hz) can be employed to depolarize poled relaxor-PbTiO3 single crystals at room temperature, without conventional heat treatment.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Kim, Hwang-Pill and Zhang, Mao-Hua and Wang, Bo and Wu, Huaiyu and Xu, Zhengze and Liu, Sipan and Moon, Sunho and Yamashita, Yohachi and Ryu, Jong Eun and Liu, Jun and et al.}, year={2024}, month={Jul} }
 @article{fan_wu_wu_garcia_jiang_zhang_zhao_yu_2025, title={Electro-elastic characteristics of KCsMoP2O9 crystal: Exploiting strong piezoelectricity for guided wave transducer applications}, volume={11}, ISSN={["2352-8478"]}, DOI={10.1016/j.jmat.2024.01.011}, abstractNote={A new piezoelectric crystal, KCsMoP2O9 (KCMP), was successfully grown by the Kyropoulos method. The electro-elastic properties of KCMP crystal were characterized by the impedance method. The full set of elastic constants was determined by solving the Christoffel equation. Remarkably, the crystal exhibits a large face-shear piezoelectric coefficient of d14 = 16.2 pC/N, surpassing that of the extensively studied ordered langasite crystal Ca3TaGa3Si2O14 (d14 = 10.4 pC/N). A fundamental shear horizontal (SH0) wave piezoelectric transducer was developed, leveraging the face-shear-mode of KCMP wafers. Finite element simulations have conclusively demonstrated the KCMP-based transducer's exceptional ability to efficiently excite and capture the pure SH0 wave, independently along two orthogonal main directions (0°/180° and 90°/270°). These results were subsequently corroborated through experimental validation at temperatures up to 300 °C, highlighting the considerable promise of KCMP crystals for utilization in non-destructive testing and structural health monitoring applications.}, number={1}, journal={JOURNAL OF MATERIOMICS}, author={Fan, Mengdi and Wu, Guangda and Wu, Huaiyu and Garcia, Nicholas and Jiang, Xiaoning and Zhang, Shujun and Zhao, Xian and Yu, Fapeng}, year={2025}, month={Jan} }
 @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"]}, url={https://www.mdpi.com/2079-6374/14/2/74}, 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{moon_xue_ganesh_shukla_kreager_cai_wu_zhu_sharma_jiang_2024, title={Ultrasound-Compatible Electrode for Functional Electrical Stimulation}, volume={12}, ISSN={["2227-9059"]}, url={https://doi.org/10.3390/biomedicines12081741}, DOI={10.3390/biomedicines12081741}, abstractNote={Functional electrical stimulation (FES) is a vital method in neurorehabilitation used to reanimate paralyzed muscles, enhance the size and strength of atrophied muscles, and reduce spasticity. FES often leads to increased muscle fatigue, necessitating careful monitoring of the patient's response. Ultrasound (US) imaging has been utilized to provide valuable insights into FES-induced fatigue by assessing changes in muscle thickness, stiffness, and strain. Current commercial FES electrodes lack sufficient US transparency, hindering the observation of muscle activity beneath the skin where the electrodes are placed. US-compatible electrodes are essential for accurate imaging and optimal FES performance, especially given the spatial constraints of conventional US probes and the need to monitor muscle areas directly beneath the electrodes. This study introduces specially designed body-conforming US-compatible FES (US-FES) electrodes constructed with a silver nanowire/polydimethylsiloxane (AgNW/PDMS) composite. We compared the performance of our body-conforming US-FES electrode with a commercial hydrogel electrode. The findings revealed that our US-FES electrode exhibited comparable conductivity and performance to the commercial one. Furthermore, US compatibility was investigated through phantom and in vivo tests, showing significant compatibility even during FES, unlike the commercial electrode. The results indicated that US-FES electrodes hold significant promise for the real-time monitoring of muscle activity during FES in clinical rehabilitative applications.}, number={8}, journal={BIOMEDICINES}, author={Moon, Sunho and Xue, Xiangming and Ganesh, Vidisha and Shukla, Darpan and Kreager, Benjamin C. and Cai, Qianqian and Wu, Huaiyu and Zhu, Yong and Sharma, Nitin and Jiang, Xiaoning}, year={2024}, month={Aug} }
 @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"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85152207991&partnerID=MN8TOARS}, 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} }
 @article{xue_wu_cai_chen_moon_huang_kim_peng_feng_sharma_et al._2024, title={Flexible Ultrasonic Transducers for Wearable Biomedical Applications: A Review on Advanced Materials, Structural Designs, and Future Prospects}, volume={71}, ISSN={["1525-8955"]}, url={https://doi.org/10.1109/TUFFC.2023.3333318}, DOI={10.1109/TUFFC.2023.3333318}, abstractNote={Due to the rapid developments in materials science and fabrication techniques, wearable devices have recently received increased attention for biomedical applications, particularly in medical ultrasound imaging, sensing, and therapy. Ultrasound is ubiquitous in biomedical applications because of its non-invasive nature, nonionic radiating, high precision, and real-time capabilities. While conventional ultrasound transducers are rigid and bulky, flexible transducers can be conformed to curved body areas for continuous sensing without restricting tissue movement or transducer shifting. This article comprehensively reviews the application of flexible ultrasound transducers in the field of biomedical imaging, sensing, and therapy. First, we review the background of flexible ultrasound transducers. Following that, we discuss advanced materials and fabrication techniques for flexible ultrasound transducers and their enabling technology status. Lastly, we highlight and summarize some promising preliminary data with recent applications of flexible ultrasound transducers in biomedical imaging, sensing, and therapy. We also provide technical barriers, challenges, and future perspectives for further research and development.}, number={7}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Xue, Xiangming and Wu, Huaiyu and Cai, Qianqian and Chen, Mengyue and Moon, Sunho and Huang, Ziping and Kim, Taeyang and Peng, Chang and Feng, Wuwei and Sharma, Nitin and et al.}, year={2024}, month={Jul}, pages={786–810} }
 @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}, volume={2023-July}, ISSN={["1944-9380"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85173598275&partnerID=MN8TOARS}, 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} }
 @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_zhang_wu_yao_shi_jiang_2023, title={Vortex-ultrasound for microbubble-mediated thrombolysis of retracted clots}, volume={123}, ISSN={["1077-3118"]}, url={https://doi.org/10.1063/5.0155223}, 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{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"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85150217532&partnerID=MN8TOARS}, 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} }
 @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{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{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_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={AbstractBackgroundLow‐intensity transcranial focused ultrasound (tFUS) has gained considerable attention as a promising noninvasive neuromodulatory technique for human brains. However, the complex morphology of the skull hinders scholars from precisely predicting the acoustic energy transmitted and the region of the brain impacted during the sonication. This is due to the fact that different ultrasound frequencies and skull morphology variations greatly affect wave propagation through the skull.PurposeAlthough the acoustic properties of human skull have been studied for tFUS applications, such as tumor ablation using a multielement phased array, there is no consensus about how to choose a single‐element focused ultrasound (FUS) transducer with a suitable frequency for neuromodulation. There are interests in exploring the magnitude and dimension of tFUS beam through human parietal bone for modulating specific brain lobes. Herein, we aim to investigate the wave propagation of tFUS on human skulls to understand and address the concerns above.MethodsBoth experimental measurements and numerical modeling were conducted to investigate the transmission efficiency and beam pattern of tFUS on five human skulls (C3 and C4 regions) using single‐element FUS transducers with six different frequencies (150–1500 kHz). The degassed skull was placed in a water tank, and a calibrated hydrophone was utilized to measure acoustic pressure past it. The cranial computed tomography scan data of each skull were obtained to derive a high‐resolution acoustic model (grid point spacing: 0.25 mm) in simulations. Meanwhile, we modified the power‐law exponent of acoustic attenuation coefficient to validate numerical modeling and enabled it to be served as a prediction tool, based on the experimental measurements.ResultsThe transmission efficiency and −6 dB beamwidth were evaluated and compared for various frequencies. An exponential decrease in transmission efficiency and a logarithmic decrease of −6 dB beamwidth with an increase in ultrasound frequency were observed. It is found that a >750 kHz ultrasound leads to a relatively lower tFUS transmission efficiency (<5%), whereas a <350 kHz ultrasound contributes to a relatively broader beamwidth (>5 mm). Based on these observations, we further analyzed the dependence of tFUS wave propagation on FUS transducer aperture size.ConclusionsWe successfully studied tFUS wave propagation through human skulls at different frequencies experimentally and numerically. The findings have important implications to predict tFUS wave propagation for ultrasound neuromodulation in clinical applications, and guide researchers to develop advanced ultrasound transducers as neural interfaces.}, 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} }
 @article{zhang_wu_jiang_2022, title={Ultrasound and magnetic dual-mode stacked transducer for sonothrombolysis with a combination of nanodroplets and magnetic nanoparticles}, volume={2022-July}, ISSN={["1944-9380"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85142937501&partnerID=MN8TOARS}, 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{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{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{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{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={AbstractOne major challenge in current microbubble (MB) and tissue plasminogen activator (tPA)-mediated sonothrombolysis techniques is effectively treating retracted blood clots, owing to the high density and low porosity of retracted clots. Nanodroplets (NDs) have the potential to enhance retracted clot lysis owing to their small size and ability to penetrate into retracted clots to enhance drug delivery. For the first time, we demonstrate that a sub-megahertz, forward-viewing intravascular (FVI) transducer can be used for ND-mediated sonothrombolysis, in vitro. In this study, we determined the minimum peak negative pressure to induce cavitation with low-boiling point phase change nanodroplets and clot lysis. We then compared nanodroplet mediated sonothrombolysis to MB and tPA mediate techniques. The clot lysis as a percent mass decrease in retracted clots was 9 ± 8%, 9 ± 5%, 16 ± 5%, 14 ± 9%, 17 ± 9%, 30 ± 8%, and 40 ± 9% for the control group, tPA alone, tPA + US, MB + US, MB + tPA + US, ND + US, and ND + tPA + US groups, respectively. In retracted blood clots, combined ND- and tPA-mediated sonothrombolysis was able to significantly enhance retracted clot lysis compared with traditional MB and tPA-mediated sonothrombolysis techniques. Combined nanodroplet with tPA-mediated sonothrombolysis may provide a feasible strategy for safely treating retracted clots.}, 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} }
 @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} }
 @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{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{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{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_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} }