@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{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{kim_kasoji_durham_dayton_2022, title={Acoustic Hologram Lens Made of Nanoparticle-Epoxy Composite Molding for Directing Predefined Therapeutic Ultrasound Beams}, ISSN={["1948-5719"]}, DOI={10.1109/IUS54386.2022.9957379}, abstractNote={We present an acoustic hologram lens fabrication method for prototyping nondeformed hologram lenses with a tailored acoustic impedance. A pixelized hologram pattern is typically manufactured by photo-curing 3D printing methods, such as stereolithography (SLA) printing. However, SLA printing has major limitations for lens fabrication: vulnerability to deformation during photo-curing of a thin-plate shape lens structure and limited controllability of acoustic impedance. To overcome these limitations, we adopted a synthesized epoxy composite molding technique in this work. The used alumina nanoparticle (300 nm)-epoxy composite contains 22.5% alumina particles in volume. The characterized acoustic impedance of the composite was 4.68 MRayl whereas the conventional photopolymer exhibited 3.13 MRayl. We used these acoustic properties in lens modeling and acoustic hologram simulations. In simulations, the composite lens generated 145% pressure amplitude of the photopolymer lens due to improved acoustic impedance matching between a piezoelectric ceramic and water medium. We prototyped a composite lens through 1) 3D printing a lens cavity, 2) silicone rubber molding, and 3) epoxy composite lens molding. We observed no deformation of the prototyped composite lens whereas the photopolymer lens showed deformed edges. The beam mapping result using the composite lens showed 17% improved structural similarity with the designed pressure pattern compared to the photopolymer result. Due to the air bubbles trapped in a composite lens, the expected improvement of pressure amplitude over a photopolymer lens was not experimentally demonstrated. The additional degassing procedure will be included for future prototypes and pressure transmission will be evaluated.}, journal={2022 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS)}, author={Kim, Jinwook and Kasoji, Sandeep and Durham, Phillip G. and Dayton, Paul A.}, 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{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{durham_kim_eltz_caskey_dayton_2022, title={POLYVINYL ALCOHOL CRYOGELS FOR ACOUSTIC CHARACTERIZATION OF PHASE-CHANGE CONTRAST AGENTS}, volume={48}, ISSN={["1879-291X"]}, DOI={10.1016/j.ultrasmedbio.2022.01.007}, abstractNote={Phase-change contrast agents (PCCAs) consisting of lipid-encapsulated low-boiling-point perfluorocarbons can be used in conjunction with ultrasound for diagnostic and therapeutic applications. One benefit of PCCAs is site-specific activation, whereby the liquid core is acoustically vaporized into a bubble detectable via ultrasound imaging. For further evaluation of PCCAs in a variety of applications, it is useful to disperse these nanodroplets into an acoustically compatible stationary matrix. However, many traditional phantom preparations require heating, which causes premature thermal activation of low-boiling-point PCCAs. Polyvinyl alcohol (PVA) cryogels do not require heat to set. Here we propose a simple method for the incorporation of the low-boiling-point PCCAs using octafluoropropane (OFP) and decafluorobutane (DFB) into PVA cryogels for a variety of acoustic characterization applications. We determined the utility of the phantoms by activating droplets with a focused transducer, visualizing the lesions with ultrasound imaging. At 1 MHz, droplet activation was consistently observed at 2.0 and 4.0 MPa for OFP and DFB, respectively.}, number={5}, journal={ULTRASOUND IN MEDICINE AND BIOLOGY}, author={Durham, Phillip G. and Kim, Jinwook and Eltz, Katherine M. and Caskey, Charles F. and Dayton, Paul A.}, year={2022}, month={May}, pages={954–960} }
 @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={• Multiple pillar piezoelectric stack design for intravascular sono-thrombolysis. • High (>3MPa) acoustic pressure output and long (>2.2 wavelengths) focal distance. • Fast lysis rate (3.8–5.0 mg/min) through cavitation effect of infused nanodroplets. • In-vitro validation of the therapeutic efficacy through a flow model. 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 mm 3 . 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 V pp , 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{kim_kasoji_durham_dayton_2021, title={Acoustic holograms for directing arbitrary cavitation patterns}, volume={118}, ISSN={["1077-3118"]}, DOI={10.1063/5.0035298}, abstractNote={Cavitation is an important phenomenon in biomedical acoustics. It can produce both desired outcomes (i.e., local therapeutic effects in vivo) and undesired outcomes (i.e., tissue damage), and it is, thus, important to both understand and direct cavitation fields. Through the use of three-dimensional-printed acoustic lenses and cavitation-sensitive acoustic phantoms, we demonstrate the generation of arbitrary shape two-dimensional (2D) microbubble cavitation fields. In this study, we demonstrate shaping a 1 MHz acoustic beam as the character “7” on a target plane that contains a higher mechanical index than the cavitation threshold for encapsulated microbubbles in a gelatin phantom. The lens pattern is first designed by calculating the phase map of the desired field using an angular spectrum approach. After lens implementation, acoustic pulsing through the lens generated the target acoustic field in a phantom and produced a cavitation map following the intended 2D pattern. The cavitation pattern was similar (with the structural similarity of 0.476) to the acoustic pressure map of the excitation beam.}, number={5}, journal={APPLIED PHYSICS LETTERS}, author={Kim, Jinwook and Kasoji, Sandeep and Durham, Phillip G. and Dayton, Paul A.}, year={2021}, month={Feb} }
 @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_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{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 One 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} }
 @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{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} }
 @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. Because of the integrated device architecture, the resulting p-OLED features a high acousto-optic conversion efficiency at the resonance 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{kim_roh_2020, title={Modeling and Design of a Rear-Mounted Underwater Projector Using Equivalent Circuits}, volume={20}, ISBN={1424-8220}, DOI={10.3390/s20247085}, abstractNote={Tonpilz is a popular transducer for underwater projector arrays for sonar systems. For low-frequency transmission, a larger axial dimension of the conventional Tonpilz transducer is required. However, a bulky and heavy Tonpilz element is not suitable due to limitations in terms of the space and payload of the array platform. To address this problem, we developed a rear-mounted Tonpilz transducer to generate a sub-fundamental resonance in addition to the common longitudinal resonance. For this purpose, we developed a new equivalent circuit model that can reflect all the effects of the key design parameters of the transducer, such as suspension thickness (stiffness), tail mass thickness, and head mass thickness. The impedance and transmitting voltage response were evaluated as performance factors at both resonance frequencies. The validity of the circuit was verified by comparing the analysis results with those from the finite element analysis of the same transducer. Based on the results, the transducer structure was designed to have comparable transmitting performance at both resonance frequencies by employing relatively high suspension stiffness, light tail mass, and heavy head mass. The novel design can permit the dual-band operation of the transducer so that the transducer can operate as a wideband projector.}, number={24}, journal={SENSORS}, author={Kim, Jinwook and Roh, Yongrae}, year={2020}, month={Dec} }
 @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_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 [Formula: see text] for TX elements and 140 [Formula: see text] 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{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{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- [Formula: see text]-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} }
 @book{jiang_li_kim_ma_2017, title={High frequency piezo-composite micromachined ultrasound transducer array technology for biomedical imaging}, DOI={10.1115/1.860441}, 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 (S<sub>0</sub>) and antisymmetric (A<sub>0</sub>) mode Lamb waves were successfully propagated in the thin stainless steel plate. The time-of- flight (TOF) of the S<sub>0</sub> and A<sub>0</sub> 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 &deg;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 Effective removal or dissolution of large blood clots remains a challenge in clinical treatment of acute thrombo-occlusive diseases. Here we report the development of an intravascular microbubble-mediated sonothrombolysis device for improving thrombolytic rate and thus minimizing the required dose of thrombolytic drugs. We hypothesize that a sub-megahertz, forward-looking ultrasound transducer with an integrated microbubble injection tube is more advantageous for efficient thrombolysis by enhancing cavitation-induced microstreaming than the conventional high-frequency, side-looking, catheter-mounted transducers. We developed custom miniaturized transducers and demonstrated that these transducers are able to generate sufficient pressure to induce cavitation of lipid-shelled microbubble contrast agents. Our technology demonstrates a thrombolysis rate of 0.7 ± 0.15 percent mass loss/min in vitro without any use of thrombolytic drugs.}, 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{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 (d31 = -1330 pC/N) of the constituent 0.67Pb(Mg <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/3</sub> Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sub> )O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> - 0.33PbTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">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{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} }
 @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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> 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 $\sim 1.7\times $ 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{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 generated from the vortex lift-up by applying opposite poling vectors to the: piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces and it showed high sensitivity to shear stress (=91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of PMN-33%PT (d31=-1330 pC/N). The sensor also showed almost no 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 0-800 Hz. Keywords: Piezoelectric sensor, shear stress, floating element, electromechanical symmetry}, 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} }
 @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{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{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{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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> 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{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{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 mm<sup>3</sup>) showed a -6 dB fractional bandwidth of 56.5% for the transmitter, and 41.8% for the receiver. A 2 MHz-transmitter (730 &mu;m pitch and 6.5 mm elevation aperture) and a 22 MHz-receiver (240 &mu;m 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 V<sub>pp</sub>, 1-cycle 2 MHz burst, which is high enough to excite microbubbles for nonlinear responses. The 7<sup>th</sup> 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{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 × 10(10) Ω · cm. The resonance 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{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} }
 @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} }