Functional Comparison of Acoustic Admittance Measurements with a CMOS-Compatible p–v Microprobe and a Reference One

Abstract

Recent developments in MEMS technology made available a new class of thermo-resistive sensors to be used as functional devices for acoustic particle velocity, v, measurements (Bruschi and Piotto, IEEE Sensors Proceedings 1405–1408, 2011). A very interesting feature of this new generation of v-sensors—distinguishing them from the Microflown^® ones (de Bree et al., Sens Actuators A Phys 54:552–557, 1996)—is their compatibility with standard CMOS industrial processes, so allowing to integrate in the same chip both the sensors and read-out electronic circuits. This added flexibility of v-sensors, combined with miniature or MEMS microphones, allows of setting up pressure–velocity (p–v) microprobes for specific applications, in particular when the reduction of production costs is decisive for marketing strategies. In many applications, in fact, carefully designed functional devices can be safely used, without prejudice to the reliability and the robustness of the required measurement process. In other words, the required measurement precision can be achieved despite the low signal-to-noise ratio or limited band frequency response of the used p–v microprobes. This article shows a first comparison between the two kinds of sensors.