Focused high frequency needle transducer for ultrasonic imaging and trapping

Hsu, Hui-Tsung; Fan, Zheng; Li, Ying; Lee, Changyang; Zhou, Qifa; Shung, K. Kirk

doi:10.1063/1.4736731

Cited by 38 publications

(29 citation statements)

References 10 publications

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“…Although the LiNbO 3 single crystal is the dominant piezoelectric material for SSAW and single beam tweezers, the superior piezoelectric and dielectric properties of relaxor-PT single crystals have also been studied for particle manipulations using microfluidic devices [508,509] and needle transducers [510]. The common motivation to use PMN-PT single crystals is the miniaturization of the ultrasound transducer with an acceptable radiation force.…”

Section: Figure Of Merits (Fom) Of Piezoelectric Materials For Vmentioning

confidence: 99%

Advantages and challenges of relaxor-PbTiO3 ferroelectric crystals for electroacoustic transducers – A review

Zhang

Jiang

et al. 2015

Progress in Materials Science

675

339

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Relaxor-PbTiO3 (PT) based ferroelectric crystals with the perovskite structure have been investigated over the last few decades due to their ultrahigh piezoelectric coefficients (d33 > 1500 pC/N) and electromechanical coupling factors (k33 > 90%), far outperforming state-of-the-art ferroelectric polycrystalline Pb(Zr,Ti)O3 ceramics, and are at the forefront of advanced electroacoustic applications. In this review, the performance merits of relaxor-PT crystals in various electroacoustic devices are presented from a piezoelectric material viewpoint. Opportunities come from not only the ultrahigh properties, specifically coupling and piezoelectric coefficients, but through novel vibration modes and crystallographic/domain engineering. Figure of merits (FOMs) of crystals with various compositions and phases were established for various applications, including medical ultrasonic transducers, underwater transducers, acoustic sensors and tweezers. For each device application, recent developments in relaxor-PT ferroelectric crystals were surveyed and compared with state-of-the-art polycrystalline piezoelectrics, with an emphasis on their strong anisotropic features and crystallographic uniqueness, including engineered domain - property relationships. This review starts with an introduction on electroacoustic transducers and the history of piezoelectric materials. The development of the high performance relaxor-PT single crystals, with a focus on their uniqueness in transducer applications, is then discussed. In the third part, various FOMs of piezoelectric materials for a wide range of ultrasound applications, including diagnostic ultrasound, therapeutic ultrasound, underwater acoustic and passive sensors, tactile sensors and acoustic tweezers, are evaluated to provide a thorough understanding of the materials’ behavior under operational conditions. Structure-property-performance relationships are then established. Finally, the impacts and challenges of relaxor-PT crystals are summarized to guide on-going and future research in the development of relaxor-PT crystals for the next generation electroacoustic transducers.

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Section: Figure Of Merits (Fom) Of Piezoelectric Materials For Vmentioning

confidence: 99%

Advantages and challenges of relaxor-PbTiO3 ferroelectric crystals for electroacoustic transducers – A review

Zhang

Jiang

et al. 2015

Progress in Materials Science

675

339

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“…In these approaches, in order to move a trapped microparticle, a mechanical scanning stage has to be utilized to move the transducer and its focus. [7][8][9] In this paper, we present results showing that it is possible to trap and move microparticles with a high frequency ultrasonic linear phased array without mechanical movement of the transducer.An ultrasonic linear phased array transducer (or simply called phased array) is a transducer consisting of multiple small transducer elements, which usually are rectangular in shape and arranged on a straight line. Ultrasonic phased arrays have been widely used in biomedical imaging 10 and industrial nondestructive testing.…”

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confidence: 99%

Acoustic trapping with a high frequency linear phased array

et al. 2012

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A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 lm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array. Similar to the trapping mechanism of optical tweezers, 1,2 when acoustic gradient force (from refraction) exceeds scattering force (from reflection), an object can be attracted and trapped by a tightly focused ultrasound beam. 3,4 The direct exposure of cells to the optical trapping laser beam may induce photodamage, 5 however, it was demonstrated that the thermal and mechanical effects in acoustic trapping are negligible when the energy is maintained in the diagnostic range. 6 Recently, high frequency single element ultrasonic transducers have been used to carry out single beam acoustic trapping. In these approaches, in order to move a trapped microparticle, a mechanical scanning stage has to be utilized to move the transducer and its focus. [7][8][9] In this paper, we present results showing that it is possible to trap and move microparticles with a high frequency ultrasonic linear phased array without mechanical movement of the transducer.An ultrasonic linear phased array transducer (or simply called phased array) is a transducer consisting of multiple small transducer elements, which usually are rectangular in shape and arranged on a straight line. Ultrasonic phased arrays have been widely used in biomedical imaging 10 and industrial nondestructive testing. 11 The advantages of phased array transducers over conventional single element transducers are their capabilities of steering the ultrasound beam into different directions and/or changing the focus at different depths, not by mechanically moving transducers but by applying electronic phase shift/time delays on the transmitting pulses to the elements of the phased array. Eliminating the mechanical movement of the transducer increases the system reliability and the speed of the experiment.A customized lead zirconate titanate (PZT-5 H) 2-2 composite linear phased array transducer was fabricated with traditional array technology. 12 The center frequency of the phased array is 26.3 MHz. The array has 64 small elements arranged on a straight line in the azimuthal direction. The elevation length and lateral width of one element are 2 mm and 24 lm, respectively. The kerf between two adjacent elements is 6 lm. The F-number of the phased array is 2.6.A field programmable gate array (FPGA) based 64-channel transmit beamformer and a 64-channel pulser were also developed to drive the phased array. The transmit beamformer could send out 128 (64 pairs) delayed trigger signals, 13 with whic...

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“…The trapping performance of both types of SBAT was demonstrated previously. 11,12 Needle type transducers may be positioned closer to the particles to be trapped or cells inside of blood vessels transcutaneously after piercing through skin and tissues. The acoustic beam generated by phased array transducers could be dynamically focused at different depths and angles; therefore, no mechanical movement of transducer is required.…”

mentioning

confidence: 99%

A feasibility study of in vivo applications of single beam acoustic tweezers

Liu

Lee

Chen

et al. 2014

Applied Physics Letters

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Tools that are capable of manipulating micro-sized objects have been widely used in such fields as physics, chemistry, biology, and medicine. Several devices, including optical tweezers, atomic force microscope, micro-pipette aspirator, and standing surface wave type acoustic tweezers have been studied to satisfy this need. However, none of them has been demonstrated to be suitable for in vivo and clinical studies. Single beam acoustic tweezers (SBAT) is a technology that uses highly focused acoustic beam to trap particles toward the beam focus. Its feasibility was first theoretically and experimentally demonstrated by Lee and Shung several years ago. Since then, much effort has been devoted to improving this technology. At present, the tool is capable of trapping a microparticle as small as 1 lm, as well as a single red blood cell. Although in comparing to other microparticles manipulating technologies, SBAT has advantages of providing stronger trapping force and deeper penetration depth in tissues, and producing less tissue damage, its potential for in vivo applications has yet been explored. It is worth noting that ultrasound has been used as a diagnostic tool for over 50 years and no known major adverse effects have been observed at the diagnostic energy level. This paper reports the results of an initial attempt to assess the feasibility of single beam acoustic tweezers to trap microparticles in vivo inside of a blood vessel. The acoustic intensity of SBAT under the trapping conditions that were utilized was measured. The mechanical index and thermal index at the focus of acoustic beam were found to be 0.48 and 0.044, respectively, which meet the standard of commercial diagnostic ultrasound system. V C 2014 AIP Publishing LLC.[http://dx.doi.org/10.1063/1.4900716] Similar to physics involved in optical trapping, 1 a steep intensity gradient of the acoustic microbeam coupled with a minimal difference in acoustic impendence between microparticles and the surrounding medium results in a net acoustic radiation force (gradient force) on the particle in moving it towards the beam axis. It was first theoretically and experimentally demonstrated by Lee and Shung. 2 Several in vitro applications of single beam acoustic tweezers (SBAT) have been explored. It has been demonstrated to be capable of manipulating a single cell and estimating the deformability of red blood cells and assaying the invasion potential of breast cancer cells. 3,4 However, its enormous potentials for in vivo applications have not been explored.Obviously, technologies like micro-pipette aspiration and atomic force microscopy, which have very short working distance or requires direct contact with the objects to be controlled, are not suitable for the in vivo study. Technologies for noncontact manipulation of microparticles also are available, i.e., laser beam 1 and electron beam, 5 but they suffer from poor penetration in skin and other human tissues. Additionally, heat generated by the highly focused laser and electron beams may cause tissue dama...

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Focused high frequency needle transducer for ultrasonic imaging and trapping

Cited by 38 publications

References 10 publications

Advantages and challenges of relaxor-PbTiO3 ferroelectric crystals for electroacoustic transducers – A review

Advantages and challenges of relaxor-PbTiO3 ferroelectric crystals for electroacoustic transducers – A review

Acoustic trapping with a high frequency linear phased array

A feasibility study of in vivo applications of single beam acoustic tweezers

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