A fully-populated 32×32 CMUT-in-CMOS array

As ultrasound imagers become increasingly portable and lower cost, breakthroughs in transducer technology will be needed in order to provide excellent imaging (ideally 3D/4D) while maintaining the affordability needed for portable systems. This paper presents a 32×32 ultrasound array prototype, manufactured using a CMUT-in-CMOS approach whereby transducer elements and circuit components are integrated on a single chip using a straightforward and cost-effective manufacturing approach. The array contains 1,024 elements arranged on a hexagonal grid with half-wavelength pitch (target of 2-4 MHz). On chip CMOS buffers and multiplexers are used to maintain signal integrity and to reduce the number of output leads. For testing and imaging studies, the array has been interfaced to a commercial imager as well as a set of custom transmit and receive electronics. This work sets the stage for full-scale 2D arrays that will provide unprecedented image quality at a very low cost.