An AlN MEMS Piezoelectric Microphone for Aeroacoustic Applications

TitleAn AlN MEMS Piezoelectric Microphone for Aeroacoustic Applications
Publication TypeJournal Article
Year of Publication2012
AuthorsWilliams, M. D., B. A. Griffin, T. N. Reagan, J. R. Underbrink, and M. Sheplak
JournalJournal of Microelectromechanical Systems
Start Page270
Date Published04/2012
Type of ArticleJournal


This paper describes the development of a micro-machined microphone for aircraft fuselage arrays that are utilized by aeroacousticians to help identify aircraft noise sources and/or assess the effectiveness of noise-reduction technologies.  The developed microphone utilizes piezoelectric transduction via an integrated aluminum nitride layer in a thin-film composite diaphragm. A theoretical lumped element model and an associated noise model of the complete microphone system are developed and utilized in a formal design-optimization process. Optimal designs were fabricated using a variant of the film bulk acoustic resonator process at Avago Technologies. The experimental characterization of one design is presented here, and measured performance was in line with sponsor specifications, including a sensitivity of −39 μV/Pa, a minimum detectable pressure of 40.4 dB, a confirmed bandwidth up to 20 kHz, a 129.5-kHz resonant frequency, and a 3% distortion limit approaching 172 dB. With this performance—in addition to its small size—this microphone is shown to be a viable enabling technology for low-cost high-resolution fuselage array measurements.
Refereed DesignationRefereed