A Silicon Micromachined Microphone for Aeroacoustics Measurements – APS Division of Fluid Dynamics Nov 1998

Advanced diagnostic techniques for the measurement of noise in forward flight aeroacoustic simulation experiments plays an important role in verifying noise suppression methods and guides the development of analytical models. Unfortunately, existing commercial microphone technology cannot meet the requirements of forward-flight wind-tunnel testing. This paper presents the development of a silicon-micromachined, piezoresistive microphone for wind-tunnel testing. The goal of this research program is to develop a scientific measurement tool that exceeds the temporal and spatial resolution capabilities of commercially available microphones. The microphone consists of four dielectrically-isolated, single-crystal silicon piezoresistors on top of a 1500 A-thick, 210 um-diameter silicon-nitride membrane. Preliminary measurements indicate a five-fold increase in sensitivity and a two-order-of-magnitude decrease in power consumption over commercially available silicon microphones. The design and fabrication of this device will be discussed and experimental results presented.

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