Fundamental performance characterisation of high frequency piezocomposites made with net-shape viscous polymer processing for medical ultrasound transducers

MacLennan, D.; Button, Tim W.; Elgoyhen, J.; Hughes, H.; Meggs, C.; Corner, George; Démoré, Christine; Cochran, Sandy; Zhang, D.

doi:10.1109/ultsym.2008.0015

Cited by 5 publications

(5 citation statements)

References 7 publications

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“…The effective coupling coefficient, k eff , was calculated from the electrical impedance spectrum and was found to be 0.51. This compares with similar values of 1-3 PZT/polymer composites resonating at lower frequencies [34][35][36][37].…”

Section: Characterization Of the Pillar Arrays And 1-3 Compositessupporting

confidence: 83%

Application of gel-casting to the fabrication of 1–3 piezoelectric ceramic–polymer composites for high-frequency ultrasound devices

Garcia‐Gancedo¹,

Olhero²,

Alves³

et al. 2012

J. Micromech. Microeng.

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A modified gel-casting technique was used to fabricate a 1-3 piezoelectric ceramic/polymer composite substrate formed by irregular-shaped pillar arrays of small dimensions and kerfs. This technique involves the polymerization of aqueous piezoelectric (PZT) suspensions with added water-soluble epoxy resin and polyamine-based hardener that lead to high strength, high density and resilient ceramic bodies. Soft micromoulding was used to shape the ceramic segments, and micropillars with lateral features down to 4 μm and height-to-width aspect ratios of ∼10 were achieved. The composite exhibited a clear thickness resonance mode at approximately 70 MHz and a k eff ∼ 0.51, demonstrating that the ceramic micropillars possess good electrical properties. Furthermore, gel-casting allows the fabrication of ceramic structures with non-conventional shapes; hence, device design is not limited by the standard fabrication methods. This is of particular benefit for high-frequency transducers where the critical design dimensions are reduced.

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Section: Characterization Of the Pillar Arrays And 1-3 Compositessupporting

confidence: 83%

Application of gel-casting to the fabrication of 1–3 piezoelectric ceramic–polymer composites for high-frequency ultrasound devices

Garcia‐Gancedo¹,

Olhero²,

Alves³

et al. 2012

J. Micromech. Microeng.

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“…The -6 dB axial resolution is 69 μm for the Random 1 transducer and 31 μm for Random 2. These are reasonable figures when compared with the values reported for regular piezocomposite transducers made by other fabrication methods [9]. D. Tissue imaging A scanning system with automatic scanning stages with a SHOT-602 stage controller (Sigma Koki, Tokyo, Japan) in conjunction with the pulser-receiver mentioned earlier and LabView control software (National Instruments, Newbury, UK) were used for tissue imaging.…”

Section: Pulse-echo Measurementsupporting

confidence: 72%

Micro-moulded randomised piezocomposites for high frequency ultrasound imaging

Jiang

Démoré

Meggs

et al. 2012

2012 IEEE International Ultrasonics Symposium

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1-3 piezocomposites that can operate at over 30 MHz are in demand to improve spatial resolution on a sub-millimetre level for biomedical ultrasound imaging applications. However, the fabrication of such materials remains a challenge as ultrafine dimensions are required in conventional composite designs. We have previously reported the design of randomised composites to eliminate coupling to lateral modes and to relax overall dimensional constraints. In this work, practical fabrication of composites based on these designs has been realised by using a novel micro-moulding approach combining gel casting with soft lithography. Impedance spectra of randomised composites confirm their advantage for suppressing spurious modes. Pulse-echo responses of two completed transducers operating at 30 and 70 MHz have demonstrated their functional performance.

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“…The tape-casting method [12] was used to produce 18-MHz and 25-MHz 2–2 piezoceramic composite (22-μm-wide pillars and 4.5-μmwide kerfs) with a measured k t of 0.52 and 0.62, respectively. Finally, a 36-MHz 1–3 composite fabricated using micromolding techniques (15-μm-pillar widths with a 50% piezoceramic volume fraction) recorded a k t value of approximately 0.5 [21]. Unfortunately, these composite manufacturing studies did not report other critical material properties, such as tan( δ S e ), Q m , and α ; therefore, further research is warranted to determine if there is a preferred method.…”

Section: Materials Methods and Resultsmentioning

confidence: 99%

“…All of these parameters could be evaluated in the future to determine ways to reduce performance degradation caused by mechanical dicing. It was also noted that other piezoceramic composite manufacturing techniques [3], [12], [21] were capable of achieving k t values comparable to what was recorded for composites manufactured using the IB method; however, further studies are needed to make definitive comparisons. Laser-dicing [5] and/or dry-etching [10] should also be evaluated extensively to determine if they are more- or less-effective techniques for producing fine-scale piezoceramic composites for high-frequency ultrasound arrays.…”

Section: Discussionmentioning

confidence: 99%

A high-frequency linear ultrasonic array utilizing an interdigitally bonded 2-2 piezo-composite

Cannata

Williams

Zhang

et al. 2011

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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This paper describes the development of a high-frequency 256-element linear ultrasonic array utilizing an interdigitally bonded (IB) piezo-composite. Several IB composites were fabricated with different commercial and experimental piezoelectric ceramics and evaluated to determine a suitable formulation for use in high-frequency linear arrays. It was found that the fabricated fine-scale 2–2 IB composites outperformed 1–3 IB composites with identical pillar- and kerf-widths. This result was not expected and lead to the conclusion that dicing damage was likely the cause of the discrepancy. Ultimately, a 2–2 composite fabricated using a fine-grain piezoelectric ceramic was chosen for the array. The composite was manufactured using one IB operation in the azimuth direction to produce approximately 19-μm-wide pillars separated by 6-μm-wide kerfs. The array had a 50 μm (one wavelength in water) azimuth pitch, two matching layers, and 2 mm elevation length focused to 7.3 mm using a polymethylpentene (TPX) lens. The measured pulse-echo center frequency for a representative array element was 28 MHz and −6-dB band-width was 61%. The measured single-element transmit −6-dB directivity was estimated to be 50°. The measured insertion loss was 19 dB after compensating for the effects of attenuation and diffraction in the water bath. A fine-wire phantom was used to assess the lateral and axial resolution of the array when paired with a prototype system utilizing a 64-channel analog beamformer. The −6-dB lateral and axial resolutions were estimated to be 125 and 68 μm, respectively. An anechoic cyst phantom was also imaged to determine the minimum detectable spherical inclusion, and thus the 3-D resolution of the array and beamformer. The minimum anechoic cyst detected was approximately 300 μm in diameter.

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Fundamental performance characterisation of high frequency piezocomposites made with net-shape viscous polymer processing for medical ultrasound transducers

Cited by 5 publications

References 7 publications

Application of gel-casting to the fabrication of 1–3 piezoelectric ceramic–polymer composites for high-frequency ultrasound devices

Application of gel-casting to the fabrication of 1–3 piezoelectric ceramic–polymer composites for high-frequency ultrasound devices

Micro-moulded randomised piezocomposites for high frequency ultrasound imaging

A high-frequency linear ultrasonic array utilizing an interdigitally bonded 2-2 piezo-composite

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