Wide-band piezoresistive aero-acoustic microphone

Conventional acoustic microphones have limited bandwidth, hence inadequate for measuring aero-acoustic waves that require a wide bandwidth from hundreds of kHz to a few MHz and a large pressure dynamic range from ~10Pa to ~1kPa. A lumped-element model is developed and used to design and estimate the static and dynamic mechanical response of an aeroacoustic microphone. Also reported is the implementation and preliminary characterization of such a microphone with a diaphragm supported at the corners by cantilever springs and integrated with piezoresistive transducers made of metal-induced laterally crystallized polycrystalline silicon. A static sensitivity of ~0.1μV/V/Pa and a resonant frequency of 560kHz have been measured.