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The second stage of the design, fabrication, and characterization of a surface micromachined, front-vented, 64 channel (8×8), capacitively sensed pressure sensor array is described. The array was fabricated using the MEMSCAP PolyMUMPs R process, a three layer polysilicon surface micromachining process with an additional fabrication step using Parylene-C. An acoustic lumped element model was used ... read moreto model an individual microphone and then applied to the array as a whole. The computational results for the design, including mechanical components, environmental loading, fluid damping, and other acoustic elements are detailed. Theory predicts single element sensitivity of 0.65 mV/Pa at the gain stage output in the 100-40,000 Hz band. A laser Doppler velocimetry (LDV) system has been used to map the spatial motion of the elements in response to electrostatic excitation. A strong resonance appears at 410 kHz for electrostatic excitation, in agreement with mathematical models. Static stiffness measured electrostatically using an interferometer is 0.1 nm/V2, similar to the expected stiffness. Preliminary acoustic sensitivity studies show average single element acoustic sensitivity of 0.6 mV/Pa from 200 to 20 kHz. A more in depth analysis of acoustic sensitivity is ongoing as well as element-to-element variability.read less
- Krause, Joshua, Robert White, Mark Moeller, Judith Gallman, Gerard Holup, and Richard DeJong. "MEMS Pressure Sensor Array for Aeroacoustic Analysis of the Turbulent Boundary Layer." 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition (January 4, 2010). doi:10.2514/6.2010-306.