A high-frequency annular-array transducer using an interdigital bonded 1-3 composite

Self Cite

This paper describes the design and fabrication of a miniature ultrasonic phased array transducer used for intervention guidance. Currently ultrasound probes are often placed at the body surface of the patients, leading to several drawbacks including the limitation of penetration and image quality. In order to improve the reliability of the guiding process, we propose a miniature phased array transducer that can be placed adjacent to the intervention device during the interventional procedure. In this paper, we report the work that has been carried out on the development of this miniature phased array transducer. It comprised 48 elements housed in a 3-mm-diameter needle. A specially designed flexible circuit was used in accommodating the transducer array in the long, thin needle housing. The center frequency and the fractional bandwidth were approximately 20 MHz and 42% respectively, with an average crosstalk lower than −30 dB. The axial and azimuth resolutions were approximately 80 µm and 210 µm respectively. The imaging capability of the transducer was further evaluated by acquiring the B-mode images of a needle in a cow liver. The performance of the proposed phased array transducer demonstrates the feasibility of such an approach for interventional guidance.

Section: Transducer Fabricationmentioning

confidence: 99%

Fabrication and Characterization of a 20-MHz Microlinear Phased-Array Transducer for Intervention Guidance

Chiu

Kang

Eliahoo

et al. 2017

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“…The maximum crosstalk between the adjacent elements in the transducer was less than −37 dB [30]. A 5-cycle sinusoidal 50-MHz signal was generated by a function generator and was fed to the different channels of the platform to test hardware crosstalk.…”

Section: Resultsmentioning

confidence: 99%

“…It was fixed onto a motor connector. It was designed with an interdigital bonded 1–3 composite material consisting of 8 elements [30]. The final composite had 19-μm-wide posts separated by 6-μm-wide polymer kerfs.…”

Section: Methodsmentioning

confidence: 99%

A flexible annular-array imaging platform for micro-ultrasound

Qiu

Yan

Chabok

et al. 2013

Micro-ultrasound is an invaluable imaging tool for many clinical and preclinical applications requiring high resolution (approximately several tens of micrometers). Imaging systems for micro-ultrasound, including single-element imaging systems and linear-array imaging systems, have been developed extensively in recent years. Single-element systems are cheaper, but linear-array systems give much better image quality at a higher expense. Annular-array-based systems provide a third alternative, striking a balance between image quality and expense. This paper presents the development of a novel programmable and real-time annular-array imaging platform for micro-ultrasound. It supports multi-channel dynamic beamforming techniques for large-depth-of-field imaging. The major image processing algorithms were achieved by a novel field-programmable gate array technology for high speed and flexibility. Real-time imaging was achieved by fast processing algorithms and high-speed data transfer interface. The platform utilizes a printed circuit board scheme incorporating state-of-the-art electronics for compactness and cost effectiveness. Extensive tests including hardware, algorithms, wire phantom, and tissue mimicking phantom measurements were conducted to demonstrate good performance of the platform. The calculated contrast-to-noise ratio (CNR) of the tissue phantom measurements were higher than 1.2 in the range of 3.8 to 8.7 mm imaging depth. The platform supported more than 25 images per second for real-time image acquisition. The depth-of-field had about 2.5-fold improvement compared to single-element transducer imaging.

“…Selectively patterning the signal electrodes on the composite pillars was accomplished by sputtering a continuous electrode (approx. 2000 Å Au on top of 500 Å Cr) over the entire composite and then removing the electrode covering the exposed epoxy kerfs only using mechanical abrasion with a cotton swab and reagent alcohol [24]. …”

Section: Materials Methods and Resultsmentioning

confidence: 99%

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

Cannata

Williams

Zhang

et al. 2011

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.