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® process, a three layer polysilicon surface micromachining process. An acoustic lumped element circuit model was used to design the system. The results of our computations for the design, including mechanical components, environmental loading, fluid damping, and other acoustic elements are detailed. Theory predicts single element sensitivity of 1 mV/Pa at the gain stage output in the 400–40,000 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 480 kHz for electrostatic excitation, in good 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 single element acoustic sensitivity (as a function of frequency) increasing from 0.01 mV/Pa at 200 Hz to 0.16 mV/Pa at 2 kHz. A more in depth analysis of acoustic sensitivity is ongoing.

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