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TitleA resonant pressure sensor based on a squeezed film of gas
Publication TypeJournal Article
Year of Publication1993
AuthorsAndrews, M.K., Turner G.C., Harris P.D., and Harris I.M.
JournalSensors and Actuators: A. Physical
Pagination219 - 226
Date Published1993
ISSN09244247 (ISSN)
KeywordsCavity resonators, Gas dynamics, Gas spring constant, Gases, Instruments, Oscillators (mechanical), Pressure effects, PRESSURE MEASUREMENT, Pressure transducers, Resonate pressure sensors, Resonators, Squeeze film effect, Squeezed gas films
AbstractA new resonating sensor for gas pressure is described. The device measures the resonance frequency of a silicon microstructure that contains a thin film of gas trapped in the structure by the squeeze-film effect. The gas is confined in the structure during an oscillation cycle only by its viscosity. It exerts a measurable influence on the resonance frequency at a pressure of 10-2 mbar, and provides the dominant spring force at pressures near one atmosphere, where the short-term stability of the sensor is of the order 1/30 mbar. We present data showing that the resonance frequency is species independent, which implies that the compressions are isothermal. Damping, however, depends on the gas viscosity, and the measurement of the oscillator Q value allows species to be identified. In the device, the oscillating diaphragm is not under a pressure load so that long-term creep is not a consideration. Further, at higher pressures, the device directly measures the spring constant of a defined volume of gas with only a small contribution from the silicon spring constant. It therefore has potential as a long-term reference of pressure. © 1993.

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