Fabrication and performance of high-frequency composite transducers with triangular-pillar geometry

Abstract

A single-element, 40-MHz, 3-mm diameter transducer was fabricated with a geometric focus at 9 mm. The transducer was based on a piezo-composite substrate with triangular-shaped composite pillars. The 2-way bandwidth of 50% and impedance magnitude were in agreement with that predicted using finite-element modeling. A one-way radiation pattern was collected using a needle hydrophone. The one-way -3 dB beamwidth at the geometric focus was measured to be 120 microm and the -3 dB depth of field was 2.5 mm. This is in good agreement with the theoretical predictions of 112.5 microm and 2.4 mm. The triangular-pillar composite transducer was then compared with a transducer with square composite pillars with similar volume fraction of active ceramic. A 9.5 dB reduction in the amplitude of the secondary resonance was found for the triangular-pillar composite as well as a 30% gain in the 2-way pulse bandwidth. A 256-element 30-MHz linear array was fabricated as a preliminary investigation into the use of the triangular pillar as the substrate in a high-frequency linear array transducer. In vivo images were generated with both the single-element and linear-array transducers.

Crosstalk reduction for high-frequency linear-array ultrasound transducers using 1-3 piezocomposites with pseudo-random pillars

“…Compared with the SQ array subaperture, the TR array subaperture reduced its combined crosstalk by 4.3 dB to −29.6 dB. This observation also validated Brown and Yin’s results [18], [19]. Notably, the PR array subaperture had the lowest measured crosstalk of −31.8 dB, which was 6.5 and 2.2 dB lower than that of the SQ and the TR array subapertures at the same frequency, respectively.…”

“…In 2007, Brown et al . developed a 1–3 piezocomposite with mechanically diced triangular pillars (MPAR > 0.8) to reduce the influence of the lateral-mode resonances on the thickness-mode resonance within the composite by spreading the energy over a broad frequency range [18]. Compared with the square pillar composites, the triangular pillar composites showed a 9.5 dB reduction in spurious signals and a 30% gain in the 2-way pulse bandwidth.…”

Dual-Frequency Piezoelectric Transducers for Contrast Enhanced Ultrasound Imaging

“…Many of these focused single-element transducers have been possible due to the use of flexible piezoelectric composites rather than inflexible piezoelectric ceramics [ 60 , 61 ]. An important advancement for high-frequency arrays has been the development of composites with large triangular pillars to suppress lateral modes while maintaining high sensitivity [ 62 , 63 ].…”

Influence of 1-3 piezocomposite fabrications on lateral modes

“…The contribution of different pillar geometries on the electromechanical coupling factor of the composite was studied. More practically, the design of a piezocomposite with triangular pillars was manufactured and the measurements showed that this geometry improves some essential characteristics, in particular for high frequency imaging applications [4].…”