Development of high frequency annular array ultrasound transducers using interdigital bonded composites

The design, fabrication, and testing of 1–3 composite annular array transducers is presented. An interdigital bonded (IB) 1–3 composite was manufactured using two IB operations on a fine-grain piezoelectric ceramic. Unloaded epoxy was used for both the matching and backing layers and a flexible circuit was used for interconnect. The final composite had 19µm wide posts separated by 6µm wide polymer kerfs. One array was tested and the results were found to be in good agreement with KLM modeled results. The average measured pulse-echo response for array elements was 34.3 MHz with 57.5 % −6 dB bandwidth. The maximum crosstalk between neighbor elements was −38.5 dB. A novel fabrication step greatly simplified fabrication process by eliminating the need for electrode patterning and alignment of that pattern between the composite and flex circuit.