@article{li_kim_wang_kasoji_lindsey_dayton_jiang_2018, title={A Dual-Frequency Colinear Array for Acoustic Angiography in Prostate Cancer Evaluation}, volume={65}, ISSN={["1525-8955"]}, DOI={10.1109/TUFFC.2018.2872911}, abstractNote={Approximately 80% of men who reach 80 years of age will have some form of prostate cancer. The challenge remains to differentiate benign and malignant lesions. Based on recent research, acoustic angiography, a novel contrast-enhanced ultrasound imaging technique, can provide high-resolution visualization of tissue microvasculature and has demonstrated the ability to differentiate vascular characteristics between healthy and tumor tissue in preclinical studies. We hypothesize that transrectal acoustic angiography may enhance the assessment of prostate cancer. In this paper, we describe the development of a dual frequency, dual-layer colinear array transducer for transrectal acoustic angiography. The probe consists of 64 transmitting (TX) elements with a center frequency of 3 MHz and 128 receiving (RX) elements with a center frequency of 15 MHz. The dimensions of the array are 18 mm in azimuth and 9 mm in elevation. The pitch is  $280~\mu \text{m}$  for TX elements and 140  $\mu \text{m}$  for RX elements. Pulse-echo tests of TX/RX elements and aperture acoustic field measurements were conducted, and both results were compared with the simulation results. Real-time contrast imaging was performed using a Verasonics system and a tissue-mimicking phantom. Nonlinear acoustic responses from microbubble contrast agents at a depth of 35 mm were clearly observed. In vivo imaging in a rodent model demonstrated the ability to detect individual vessels underneath the skin. These results indicate the potential use of the array described herein for acoustic angiography imaging of prostate tumor and identification of regions of neovascularization for the guidance of prostate biopsies.}, number={12}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Li, Sibo and Kim, Jinwook and Wang, Zhuochen and Kasoji, Sandeep and Lindsey, Brooks D. and Dayton, Paul A. and Jiang, Xiaoning}, year={2018}, month={Dec}, pages={2418–2428} }
 @article{wang_martin_dayton_jiang_2018, title={Real-time ultrasound angiography using superharmonic dual-frequency (2.25 MHz/30 MHz) cylindrical array: In vitro study}, volume={82}, ISSN={["1874-9968"]}, DOI={10.1016/j.ultras.2017.09.012}, abstractNote={Recent studies suggest that dual-frequency intravascular ultrasound (IVUS) transducers allow detection of superharmonic bubble signatures, enabling acoustic angiography for microvascular and molecular imaging. In this paper, a dual-frequency IVUS cylindrical array transducer was developed for real-time superharmonic imaging. A reduced form-factor lateral mode transmitter (2.25MHz) was used to excite microbubbles effectively at 782kPa with single-cycle excitation while still maintaining the small size and low profile (5Fr) (3Fr=1mm) for intravascular imaging applications. Superharmonic microbubble responses generated in simulated microvessels were captured by the high frequency receiver (30MHz). The axial and lateral full-width half-maximum of microbubbles in a 200-μm-diameter cellulose tube were measured to be 162μm and 1039μm, respectively, with a contrast-to-noise ratio (CNR) of 16.6dB. Compared to our previously reported single-element IVUS transducers, this IVUS array design achieves a higher CNR (16.6dBvs 11dB) and improved axial resolution (162μmvs 616μm). The results show that this dual-frequency IVUS array transducer with a lateral-mode transmitter can fulfill the native design requirement (∼3-5Fr) for acoustic angiography by generating nonlinear microbubble responses as well as detecting their superharmonic responses in a 5Fr form factor.}, journal={ULTRASONICS}, author={Wang, Zhuochen and Martin, K. Heath and Dayton, Paul A. and Jiang, Xiaoning}, year={2018}, month={Jan}, pages={298–303} }
 @article{wang_martin_huang_dayton_jiang_2017, title={Contrast Enhanced Superharmonic Imaging for Acoustic Angiography Using Reduced Form-Factor Lateral Mode Transmitters for Intravascular and Intracavity Applications}, volume={64}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2016.2619687}, abstractNote={Techniques to image the microvasculature may play an important role in imaging tumor-related angiogenesis and vasa vasorum associated with vulnerable atherosclerotic plaques. However, the microvasculature associated with these pathologies is difficult to detect using traditional B-mode ultrasound or even harmonic imaging due to small vessel size and poor differentiation from surrounding tissue. Acoustic angiography, a microvascular imaging technique that utilizes superharmonic imaging (detection of higher order harmonics of microbubble response), can yield a much higher contrast-to-tissue ratio than second harmonic imaging methods. In this paper, two dual-frequency transducers using lateral mode transmitters were developed for superharmonic detection and acoustic angiography imaging in intracavity applications. A single element dual-frequency intravascular ultrasound transducer was developed for concept validation, which achieved larger signal amplitude, better contrast-to-noise ratio (CNR), and pulselength compared to the previous work. A dual-frequency [Pb(Mg<sub>1/3</sub>Nb<sub>2/3</sub>)O<sub>3</sub>]–x[PbTiO<sub>3</sub>] array transducer was then developed for superharmonic imaging with dynamic focusing. The axial and lateral sizes of the microbubbles in a 200-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> tube were measured to be 269 and <inline-formula> <tex-math notation="LaTeX">$200~\mu \text{m}$ </tex-math></inline-formula>, respectively. The maximum CNR was calculated to be 22 dB. These results show that superharmonic imaging with a low frequency lateral mode transmitter is a feasible alternative to thickness mode transmitters when the final transducer size requirements dictate design choices.}, number={2}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Wang, Zhuochen and Martin, K. Heath and Huang, Wenbin and Dayton, Paul A. and Jiang, Xiaoning}, year={2017}, month={Feb}, pages={311–319} }
 @inproceedings{wang_martin_dayton_jiang_2016, title={A dual frequency ivus transducer with a lateral mode transmitter for contrast enhanced intravascular ultrasound imaging}, DOI={10.1115/imece2015-51131}, abstractNote={Recent studies suggest that dual frequency intravascular ultrasound (IVUS) transducers are promising in contrast ultrasound for molecular imaging or vasa vasorum (VV) assessment to identify vulnerable plaques. Low frequency (1–3 MHz) acoustic waves are widely used for contrast imaging because it can excite microbubbles more effectively. However, conventional thickness mode 1–3 MHz transducers are not suitable for IVUS since bulky transducer size is not permitted in fine IVUS catheters used for coronary interventions (approx. 3-French). In this paper, a dual frequency (2.25 MHz/30 MHz) IVUS transducer with a lateral mode transmitter (2.25 MHz) and a thickness mode high frequency receiver (30 MHz) was designed, fabricated and characterized. In contrast detection tests, superharmonic microbubble responses flown through a 200 μm diameter tube was successfully detected with a contrast to noise ratio (CNR) of 13 dB and an axial resolution (−6 dB) of 0.1 μs (150 μm). The results showed that this dual frequency IVUS transducer with a lateral mode transmitter can be used to detect super-harmonic signal (12th to 15th harmonic) ideal for superharmonic imaging of microvascular structures.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2015, vol 3}, author={Wang, Z. C. and Martin, K. H. and Dayton, P. A. and Jiang, X. N.}, year={2016} }
 @inproceedings{li_kim_wang_jiang_kasoji_lindsey_dayton_2016, title={A dual-frequency co-linear array for prostate acoustic angiography}, DOI={10.1109/ultsym.2016.7728718}, abstractNote={Approximately 80% of men who reach 80-years of age will have some form of prostate cancer. The challenge remains to differentiate indolent from aggressive disease. Based on recent research, acoustic angiography, a novel contrast enhanced ultrasound imaging technique, can provide high-resolution visualization of tissue microvasculature and has demonstrated the ability to differentiate vascular characteristics between healthy and tumor tissue. We hypothesize that transrectal acoustic angiography may enhance assessment of prostate cancer. In this paper, we describe the development of a dual layer co-linear array ultrasound transducer for transrectal acoustic angiography. The KLM model and Field II were used for the element design and acoustic field simulation, respectively. The probe consists of 64 transmit elements with a center frequency of 3 MHz and 128 receive elements with a center frequency of 15 MHz. The dimensions of the array are 18 mm in azimuth and 8 mm in elevation. The pitch is 280 μm for transmitting (TX) elements and 140 μm for receiving (RX) elements. Pulse-echo test of TX/RX elements were conducted and compared with the simulation results. Real-time contrast imaging was tested using a Verasonics system. Non-linear responses from microbubble contrast agents at a depth of 18 mm were clearly observed. The axial beam width (-6 dB) and CTR were calculated from the measured signals to be 400 μm and 20 dB, respectively. These results suggest that the prototype co-linear array is capable of performing dual-frequency superharmonic imaging of microbubbles for prostate cancer assessment.}, booktitle={2016 ieee international ultrasonics symposium (ius)}, author={Li, S. B. and Kim, J. and Wang, Z. C. and Jiang, X. N. and Kasoji, S. and Lindsey, B. and Dayton, P. A.}, year={2016} }
 @article{wang_li_czernuszewicz_gallippi_liu_geng_jiang_2016, title={Design, Fabrication, and Characterization of a Bifrequency Colinear Array}, volume={63}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2015.2506000}, abstractNote={Ultrasound imaging with high resolution and large penetration depth has been increasingly adopted in medical diagnosis, surgery guidance, and treatment assessment. Conventional ultrasound works at a particular frequency, with a - 6-dB fractional bandwidth of ~ 70% , limiting the imaging resolution or depth of field. In this paper, a bifrequency colinear array with resonant frequencies of 8 and 20 MHz was investigated to meet the requirements of resolution and penetration depth for a broad range of ultrasound imaging applications. Specifically, a 32-element bifrequency colinear array was designed and fabricated, followed by element characterization and real-time sectorial scan (S-scan) phantom imaging using a Verasonics system. The bifrequency colinear array was tested in four different modes by switching between low and high frequencies on transmit and receive. The four modes included the following: 1) transmit low, receive low; 2) transmit low, receive high; 3) transmit high, receive low; and 4) transmit high, receive high. After testing, the axial and lateral resolutions of all modes were calculated and compared. The results of this study suggest that bifrequency colinear arrays are potential aids for wideband fundamental imaging and harmonic/subharmonic imaging.}, number={2}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Wang, Zhuochen and Li, Sibo and Czernuszewicz, Tomasz J. and Gallippi, Caterina M. and Liu, Ruibin and Geng, Xuecang and Jiang, Xiaoning}, year={2016}, month={Feb}, pages={266–274} }
 @inproceedings{an_wang_li_jiang_2016, title={Modeling of harmonic measurement radiated by a plane circular piston in fluids}, DOI={10.1109/spawda.2016.7830007}, abstractNote={In recent years, the use of nonlinear ultrasound in medical and industrial applications has increased rapidly. Harmonic signals, generated from nonlinear distortion of ultrasonic wave propagation in fluid or solid media, play an important role not only in ultrasonic medical imaging to provide higher resolution and higher contrast to tissue ratio, but also in nondestructive testing of fatigue cracks to provide higher sensitivity. We present a finite element model that embodies all the factors (diffraction, attenuation, receiver integration and tone-burst excitation) mentioned previously to describe the nonlinear characteristics of the ultrasonic field radiated by a plane circular piston source in fluids more accurately. A computer controlled ultrasonic system (RAM-5000 SNAP, Ritec Inc.) was used to verify the numerical predictions. The fundamental and the second harmonic versus axial distance are compared, and a reasonable agreement is achieved.}, booktitle={Proceedings of 2016 Symposium on Piezoelectricity, Acoustic Waves, and Device Applications (SPAWDA)}, author={An, Z. W. and Wang, Z. C. and Li, H. Y. and Jiang, X. N.}, year={2016}, pages={288–292} }
 @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} }
 @inproceedings{wang_li_liu_geng_jiang_2015, title={A bi-frequency co-linear array transducer for biomedical ultrasound imaging}, DOI={10.1115/imece2014-38871}, abstractNote={Ultrasound imaging with high resolution and large field of depth has been increasingly adopted in medical diagnosis, surgery guidance and treatment assessment because of its relatively low cost, non-invasive and capability of real-time imaging. There is always a tradeoff between the resolution and depth of field in ultrasound imaging. Conventional ultrasound works at a particular frequency, with −6 dB fractional bandwidth of < 100%, limiting the resolution or field of depth in many ultrasound imaging cases.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2014, vol 3}, author={Wang, Z. C. and Li, S. B. and Liu, R. B. and Geng, X. C. and Jiang, X. N.}, year={2015} }
 @inproceedings{ma_li_wang_jiang_2015, title={Anti-matching design for wave isolation in dual frequency transducer for intravascular super-harmonic imaging}, DOI={10.1115/imece2014-38844}, abstractNote={Intravascular super-harmonic imaging of microvessels is expected to assist understanding of atherosclerotic cardiovascular disease. A dual frequency intravascular (IVUS) ultrasound transducer is a core component transmitting at low frequency and receiving high order harmonics. A significant challenge in developing high performance dual frequency IVUS transducers is the isolation of the high frequency ultrasound echoes from the low frequency element while keeping the low frequency transmission pressure. An anti-matching layer with low impedance and quarter wavelength thickness was designed based on wave propagation theory. In both KLM modeling and prototype validation, the anti-matching layer successfully suppressed the aliasing echo to less than −20 dB. Transmission pressure of the prototype transducer was still high enough for microbubble nonlinear responses. High resolution (<0.2 mm) and high CTR (>12 dB) image was generated from super-harmonic imaging, which elucidated the capability of the transducer for intravascular microvessel detection.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2014, vol 3}, author={Ma, J. G. and Li, S. B. and Wang, Z. C. and Jiang, X. N.}, year={2015} }
 @article{wang_huang_jiang_martin_dayton_2015, title={Dual-frequency IVUS array for contrast enhanced intravascular ultrasound imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0545}, abstractNote={Recent studies suggest that contrast enhanced intravascular ultrasound (CE-IVUS) may be used for identifying vulnerable plaques through molecular imaging or detecting neovascularizations within a growing atherosclerotic lesion. However, typical intravascular ultrasound (IVUS) transducers operate at a high frequency band (20-60 MHz) which makes them not ideal for imaging microbubble contrast agents due to the less effective microbubble excitation at high frequencies. In this paper, a prototyped dual-frequency array for CE-IVUS was developed and tested. The prototype flat transducer array consists of a receiving array (32 elements, 30 MHz) built on the top of a transmitting array (8 sub-elements, 2.25 MHz) to achieve real-time superharmonic contrast enhanced imaging. The size of the receiving aperture was varied, tested and resultant images were compared. Images of a contrast-filled microtube can be observed clearly with only 4 receiving elements at an excitation voltage of 55 V, which indicates feasibility of CE-IVUS imaging after circularly wrapping the array for catheter integration.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Huang, Wenbin and Jiang, Xiaoning and Martin, K. Heath and Dayton, Paul A.}, year={2015} }
 @article{wang_jiang_czernuszewicz_gallippi_2015, title={Dual-frequency IVUS transducer for acoustic radiation force impulse (ARFI) imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0119}, abstractNote={Coronary atherosclerotic disease is the major cause of mortality in the United States. Elasticity imaging techniques such as acoustic radiation force impulse (ARFI) imaging using intravascular ultrasound (IVUS) transducers can be used to characterize coronary plaque. Conventional IVUS transducers with frequencies of 20 MHz - 60 MHz are not optimized for high-voltage, long-duration pulses required for ARFI imaging. In this work, a dual-frequency IVUS transducer, consisting of a 6.5 MHz “pushing” element and a 26 MHz “tracking” element, was designed and fabricated for ARFI application. In ARFI testing with a 160 V, 1000-cycle burst excitation, a displacement of 12.3 μm was detected in a phantom with a Young's modulus of 10 kPa at an axial depth of 3.5 mm. The result of this study suggests great potential of this dual-frequency IVUS transducer for intravascular ARFI imaging.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Jiang, Xiaoning and Czernuszewicz, Tomasz J. and Gallippi, Caterina M.}, year={2015} }
 @article{lindsey_martin_dayton_ma_wang_jiang_2015, title={Dual-frequency intravascular ultrasound imaging of microbubble contrast agents: Ex vivo and in vivo demonstration}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2015.0044}, abstractNote={Development of atherosclerotic plaques and related cardiac events are correlated with increased development of vasa vasorum, however, no currently-available diagnostic imaging method has been demonstrated effective at identifying vulnerable plaques. We present a new intravascular ultrasound (IVUS) imaging method using a dual-frequency transducer to visualize contrast flow in microvessels with high specificity. This method uses a specialized transducer capable of exciting contrast agents at a low frequency (5.5 MHz) and receiving superharmonic echoes at a much higher frequency (37 MHz). This dual-frequency transducer was used to image a cellulose micro-tube external to an ex vivo porcine artery and also using the chorioallantoic membrane of a developing chicken embryo. Using dual-frequency contrast-specific imaging, we were able to resolve vessels of a similar size to those found in vulnerable atherosclerotic plaques with clinically-relevant attenuation. The results of this study suggest contrast-specific intravascular ultrasound imaging for the detection of vulnerable plaques in atherosclerosis may provide additional diagnostic information.}, journal={2015 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Lindsey, Brooks D. and Martin, K. Heath and Dayton, Paul A. and Ma, Jianguo and Wang, Zhuochen and Jiang, Xiaoning}, year={2015} }
 @article{czernuszcwicz_gallippi_wang_ma_jiang_2014, title={Acoustic radiation force (ARF) generation with a novel dual-frequency intravascular transducer.}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0569}, abstractNote={Atherosclerosis and coronary artery disease remain the leading cause of death in the US. Coronary plaque is visualized with intravascular ultrasound (IVUS) and is typically implemented with high center frequencies (>20 MHz) for superior spatial resolution. Coronary plaque characterization may be improved by implementing elasticity imaging techniques such as acoustic radiation force impulse (ARFI) imaging using IVUS transducers. In this work we propose to extend ARFI imaging to a novel, dual-frequency small-aperture transducer design that includes a low-frequency “pushing” element and a high-frequency “tracking” element. A 40 MHz element (0.6 mm × 0.6 mm) was integrated onto a 5 MHz element (0.6 mm × 3 mm). Both elements of the transducer were fabricated from single crystal PMN-PT and the whole transducer was mounted on a 20 gauge needle tip. ARF-induced motion from the low-frequency element was quantified using optical tracking methods in a translucent phantom (~8 kPa) containing embedded graphite microparticles. Displacements induced by ARF excitations with 300, 600, 900, and 1200 cycles (5 MHz, 190 V) were captured and compared to baseline. Median (inter-quartile range) peak displacements for 300, 600, 900, and 1200 cycles were 0.33 (0.27 - 0.39) μm, 0.72 (0.62 - 0.87) μm, 1.1 (1.0 - 1.3) μm, and 1.6 (1.43 - 1.75) μm, respectively. In another phantom, 40 MHz pulse/echo RF lines were captured to demonstrate backscatter sensitivity. The results of this study show that ARF generation and high-resolution tracking is feasible on a small-aperture transducer fit for IVUS implementation.}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Czernuszcwicz, Tomasz J. and Gallippi, Caterina M. and Wang, Zhuochen and Ma, Jianguo and Jiang, Xiaoning}, year={2014}, pages={2284–2287} }
 @article{wang_ma_jiang_martin_dayton_2014, title={An array transmitter for dual-frequency contrast enhanced intravascular ultrasound imaging}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2014.0524}, abstractNote={Recent studies suggests that contrast ultrasound for molecular imaging or vasa vasorum (VV) assessment may be promising in identification of vulnerable plaques. However, conventional intravascular ultrasound (IVUS) transducers with frequency of 15 MHz - 60 MHz are not optimized for imaging with micro bubble contrast agents due to the ineffective micro bubble excitation at high frequencies and poor signal separation from tissue. This paper presents design and fabrication of a lateral mode transducer array with center frequency of 2 MHz for contrast enhanced IVUS (CE-IVUS) imaging, which can generate sufficient pressure to excite microbubbles more effectively and therefore could be used for dual-frequency microbubble superharmonic imaging, or `acoustic angiography'. Several commercial transducers with central frequency of 15 MHz, 20 MHz and 25 MHz were used as receivers to receive the contrast signal. In the contrast testing, the high frequency echo of the nonlinear response from microbubbles in a micro-tube with diameter of 0.2 mm was detected. The maximum contrast to noise ratio was 12.2 dB. The results show that superharmonic signals (over 9th harmonic) can be received; suggesting good resolution and signal separation in contrast enhanced IVUS imaging.}, journal={2014 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Ma, Jianguo and Jiang, Xiaoning and Martin, Karl Heath and Dayton, Paul A.}, year={2014}, pages={2104–2107} }
 @inproceedings{wang_li_jiang_liu_geng_2014, title={Design and phantom testing of a bi-frequency co-linear array}, booktitle={2014 IEEE International Ultrasonics Symposium (IUS)}, author={Wang, Z. C. and Li, S. B. and Jiang, X. N. and Liu, R. B. and Geng, X. C.}, year={2014}, pages={2108–2111} }
 @article{wang_yuan_jiang_jing_wang_2014, title={Disruption of microalgal cells using high-frequency focused ultrasound}, volume={153}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2013.11.054}, abstractNote={The objective of this study was to evaluate the effectiveness of high-frequency focused ultrasound (HFFU) in microalgal cell disruption. Two microalgal species including Scenedesmus dimorphus and Nannochloropsis oculata were treated by a 3.2-MHz, 40-W focused ultrasound and a 100-W, low-frequency (20kHz) non-focused ultrasound (LFNFU). The results demonstrated that HFFU was effective in the disruption of microalgal cells, indicated by significantly increased lipid fluorescence density, the decrease of cell sizes, and the increase of chlorophyll a fluorescence density after treatments. Compared with LFNFU, HFFU treatment was more energy efficient. The combination of high and low frequency treatments was found to be even more effective than single frequency treatment at the same processing time, indicating that frequency played a critical role in cell disruption. In both HFFU and LFNFU treatments, the effectiveness of cell disruption was found to be dependent on the cell treated.}, journal={BIORESOURCE TECHNOLOGY}, author={Wang, Meng and Yuan, Wenqiao and Jiang, Xiaoning and Jing, Yun and Wang, Zhuochen}, year={2014}, month={Feb}, pages={315–321} }
 @article{wang_li_jiang_liu_geng_2013, title={Design, fabrication and characterization of a bi-frequency co-linear array (7.5MHz/15MHz)}, ISSN={["1948-5719"]}, DOI={10.1109/ultsym.2013.0131}, abstractNote={Ultrasound imaging with high resolution and large field of depth is important in disease diagnosis, surgery guidance and post-surgery assessment. Conventional ultrasound imaging arrays work at a particular frequency, with -6dB fractional bandwidth of <; 100%, limiting the resolution or field of depth in many ultrasound imaging cases. This paper presented design of a 7.5 MHz / 15 MHz bi-frequency co-linear array prototype with a wide bandwidth of 5MHz-20 MHz, which can be significant in a broad range of biomedical ultrasound imaging applications. To demonstrate the concept, a 32-element 1-D linear sub-array was fabricated, followed by element characterization and beamforming tests using a Verasonics system. Beam steering at +/- 40 degree was achieved without obvious side lobes. The initial results suggest great potential of this bi-frequency co-linear array for medical imaging with high resolution and large field of depth.}, journal={2013 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS)}, author={Wang, Zhuochen and Li, Sibo and Jiang, Xiaoning and Liu, Ruibin and Geng, Xuecang}, year={2013}, pages={504–507} }
 @article{ma_wang_jiang_2013, title={Design, fabrication and test of a small aperture, dual frequency ultrasound transducer}, volume={8695}, ISSN={["1996-756X"]}, DOI={10.1117/12.2009716}, abstractNote={High resolution ultrasound medical imaging requires high frequency transducers, which usually are known with decreased penetration depth because of high loss in two-way-loop at high frequencies. To obtain high resolution imaging at large depth, a dual frequency transducer was designed for contrast imaging. Specifically, a 35 MHz receiving transducer with aperture of 0.6 mm x 0.6 mm was integrated into a 6.5 MHz transmitting transducer with aperture of 0.6 mm x 3 mm. High pressure ultrasound at low frequency was generated by the transducer to excited microbubbles in tissue. High frequency component of the nonlinear response from microbubbles were received by the 35 MHz transducer for high resolution imaging at a relatively large depth. The prototyped transducer showed the ability of transmitting about 2 MPa pressure at 6.5 MHz, under an input of 5-cycle burst at 250 Vpp, which is high enough to generate nonlinear oscillation of microbubbles. The pulse-echo test showed that the -6 dB bandwidth of the 35 MHz transducer is 34.4% and the loop sensitivity is -38.3 dB. The small aperture, dual frequency ultrasound transducers developed in this paper are promising for high resolution ultrasound medical imaging.}, journal={HEALTH MONITORING OF STRUCTURAL AND BIOLOGICAL SYSTEMS 2013}, author={Ma, Jianguo and Wang, Zhuochen and Jiang, Xiaoning}, year={2013} }