A Single-Chip CMOS-MEMS CMUT Array Transceiver With Low Bias

This study presents a novel single-chip CMOS-MEMS capacitive micromachined ultrasonic transducer (CMUT) 1D array with a 125nm capacitive transduction gap, fabricated in a conventional CMOS platform. The CMUT transceiver array (transmitter and receiver) functionality is verified via pulse-echo measurements. Remarkably, the tiny gap provides significant electromechanical coupling, resulting in a minimal operating DC bias of only 12V with a 5 V pulse as driving signals. The proposed CMOS-MEMS CMUT transceiver, encapsulated with polymer, yields satisfactory signal-to-noise ratio (SNR) under water as well as ultrasound gel environment.The 1D ultrasonic array demonstrates controllable directivity of emitting acoustic pressure, exhibiting immense promise for future beam forming and imaging applications. Utilizing the conventional CMOS platform, the array's integration of transducer and readout electronics on a single chip provides a highly compact and cost-effective solution for ultrasonic imaging. Furthermore, we proposed a dual-gap CMUT with two different dedicated transduction gaps for ultrasonic wave transmission and reception, respectively. This design further improves the ultrasonic transmission capability while retaining high receiving sensitivity with circuit integration abilities.