Integrated ultrasonic imaging systems based on CMUT arrays: recent progress

The paper describes the development of an ultrasonic imaging system based on a two-dimensional capacitive micromachined ultrasonic transducer (CMUT) array. The transducer array and front-end electronics are designed to fit in a 5-mm endoscopic channel. A custom-designed integrated circuit, which comprises the front-end electronics, is connected with the transducer elements via through-wafer interconnects and flip-chip bonding. FPGA-based signal-processing hardware provides real-time three-dimensional imaging. The imaging system is being developed to demonstrate a means of integrating the front-end electronics with the transducer array and to provide a clinically useful technology. Integration of the electronics can improve signal-to-noise ratio, reduce the number of cables connecting the imaging probe to a separate processing unit, and provide a means of connecting electronics to large two-dimensional transducer arrays. The paper describes the imaging system architecture and the progress we have made on implementing each of its components: a 16×16 CMUT array; custom-designed integrated circuits; a flip-chip bonding technique; signal-processing hardware.