Design and fabrication of a novel three-row dual frequency ultrasound transducer for image-guided drug delivery

In this study, a novel 1-3 composite three-row dual frequency ultrasound transducer was designed and fabricated for image-guided drug delivery. A novel dicing and filling method was used to fabricate 1-3 composite. The electrodes was fabricated by magnetron sputtering method, a NiCr film was sputtered with piezoelectric composite and electrode of Au to improve the adhesion between composite and electrode. Al₂O₃ powder and tungsten powder were used to fabricate matching and backing layers with epoxy. And flexible circuits were used for interconnect. The middle row was a 128-element 1D array and the outer two rows were 64-element 1.5D arrays. The outer rows were assembled at an angle of 8.75° with the middle row in a mold and fixed using epoxy. A prototype transducer was successfully fabricated and tested. The average center frequency estimated from the measured pulse-echo responses of the middle row elements was 5.22 MHz and the -6dB fractional bandwidth was 79.9%. And the average center frequency of the outer rows was 1.4MHz, the -6dB fractional bandwidth was 52.1%.