Design and Characterization of Capacitively Sensed Squeeze-Film Pressure Sensors

Compressed thin-film gas between the plates produces the squeeze-film damping force that comprises both dissipative and elastic effects. The latter is used in this paper as the mechanism to modify the structural resonance with respect to the change of ambient pressure. Capacitively sensed squeeze-film pressure sensors are implemented in a silicon-based fabrication platform. Nine designs with resonant plate sizes from 200 × 200 to 800 × 800 μm
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, and different natural frequencies for the same size are comprehensively studied. Measured sensitivities range from 94 to 762 Hz/kPa. Both simulations and measurements show the design tradeoff between sensitivity and quality factor. Required critical dimensions such as gap spacing and structural thickness to increase the squeeze-film elastic effect are also analyzed.