Characterization of 0.18-μm CMOS MEMS Capacitive Ultrasonic Sensors for Fast Photoacoustic Imaging

This work presents a 4 4 capacitive ultrasonic sensor array fabricated in a 0.18-mu m CMOS process. Compared to prior CMOS MEMS ultrasonic sensors, the smaller electrode separation in the new platform significantly improves the capacitive sensitivity. The sensor has a measured center frequency at 3.8 MHz with a fractional bandwidth of 74%. The measured sensitivity is 499 mV(pp)/MPa/V. With the advance in technology, individual readout circuit can be placed directly beneath each sensor to allow unlimited scalability. Feasibility for fast 3D photoacoustic imaging is demonstrated with the sensing array presented in this work. (C) 2016 Published by Elsevier Ltd.