Title :
A Micromachined Dual-Backplate Capacitive Microphone for Aeroacoustic Measurements
Author :
Martin, David T. ; Liu, Jian ; Kadirvel, Karthik ; Fox, Robert M. ; Sheplak, Mark ; Nishida, Toshikazu
Author_Institution :
Florida Univ., Gainesville
Abstract :
This paper presents the development of a micro-machined dual-backplate capacitive microphone for aeroacoustic measurements. The device theory, fabrication, and characterization are discussed. The microphone is fabricated using the five-layer planarized-polysilicon SUMMiT V process at Sandia National Laboratories. The microphone consists of a 0.46-mm-diameter 2.25-mum-thick circular diaphragm and two circular backplates. The diaphragm is separated from each backplate by a 2-mum air gap. Experimental characterization of the microphone shows a sensitivity of 390 muV/Pa. The dynamic range of the microphone interfaced with a charge amplifier extends from the noise floor of 41 dB/ radicHz up to 164 dB and the resonant frequency is 178 kHz.
Keywords :
acoustic measurement; aeroacoustics; aerodynamics; aircraft; capacitive sensors; diaphragms; micromachining; microphones; noise abatement; silicon; Sandia National Laboratories; aeroacoustic measurements; charge amplifier; circular backplates; circular diaphragm; distance 2 mum; five-layer planarized-polysilicon SUMMiT V process; frequency 178 kHz; micromachined dual-backplate capacitive microphone; microphone characterization; microphone fabrication; noise floor; size 0.46 mm; size 2.25 mum; Acoustic noise; Aerospace engineering; Aircraft propulsion; Bandwidth; Dynamic range; FAA; Frequency; Laboratories; Microphones; Noise reduction; Capacitive transducers; microphones; silicon micromachining;
Journal_Title :
Microelectromechanical Systems, Journal of
DOI :
10.1109/JMEMS.2007.909234
