Design and Fabrication of a Compact p-v Probe for Acoustic Impedance Measurement

A novel p–v probe for the measurement of the acoustic impedance is proposed. The device is fabricated assembling a micromachined acoustic particle velocity sensor, a commercial microphone, and an electronic read-out interface. The velocity sensor consists of two integrated polysilicon heaters placed over suspended dielectric membranes. The sensor has been designed with a commercial CMOS process and fabricated using a simple post-processing technique. The electronic interface is based on a Wheatstone bridge and a low noise instrumentation amplifier. Preliminary tests confirm the functionality of the proposed probe.