Low Cross-talk Kerfless Annular Array Ultrasound Transducers using 1-3 Piezocomposites with Pseudo-Random Pillars

This paper describes the design and fabrication of a high-frequency kerfless annular array transducer utilizing a novel 1-3 piezocomposite which was designed to reduce inter-element cross-talk. 1-3 piezocomposites have significant advantages over bulk piezoelectric materials and other types of piezocomposites; however, their benefits come at the expense of introducing more undesired interpillar resonances. At high frequencies, this is especially detrimental to kerfless annular array transducers. We have previously shown that this unwanted coupling effect (high inter-element crosstalk), can be further reduced by employing a pseudo-random pillar geometry. Utilizing the 1-3 composites with the pseudo-random pillars, a 40 MHz annular array transducer was fabricated. Each annular array was designed to have six equal-area elements and a center frequency of 40 MHz. The average center frequency estimated from the measured pulse-echo responses of array elements was 38.7 MHz and the -6 dB bandwidth was 51 %. The average insertion loss recorded was 23.1 dB, and the maximum combined crosstalk between the adjacent elements was less than -31 dB. These results demonstrate that the 1-3 piezocomposite with the pseudo-random pillars may be a better choice for fabricating enhanced high frequency linear array ultrasound transducers; especially when mechanical dicing is used.