Micromachined Arrayed Capacitive Ultrasonic Sensor/Transmitter with Parylene Diaphragms

Abstract

An arrayed device comprising 5×5 ultrasonic sensors/transmitters featuring polymer Parylene diaphragms was fabricated, and its performance was characterized. In addition to the durability and high sensitivity due to polymer nonbrittleness and flexibility, merits attributable to Parylene, such as biocompatibility, chemical resistivity, CMOS compatibility, and conformal deposition, are expected to be achieved in the future. The contents of this study are briefly summarized as follows. 1) An ultrasonic sensor with Parylene diaphragm was developed. The sensor was found to be able to receive an impulsive ultrasonic pulse transmitted by a spark discharge. The open-circuit sensitivity was 0.4 mV/Pa. 2) A well-damped waveform was obtained by setting appropriate acoustic