Novel full range vacuum pressure sensing technique using free decay of trapezoid micro-cantilever beam deflected by electrostatic force

摘要

This paper reports a novel full-range vacuum pressure sensing device, capable of exceeding the sensing range of most gauges and reducing the volume by a factor of 10. The proposed device gauges the free decay rate of a micro-cantilever beam deflected using electrostatic force and measurements of capacitance are used to determine the free decay rate of the sensing beam with respect to deflection force and vacuum pressure. This novel design enables the full-range measurement of vacuum pressure from 0.2 to 1 × 10~(-8) torr. The trapezoidal micro-cantilever beam provides uniform in-plane stress across the surface of the beam, while a thick square plate connected to the trapezoid beam serves as a proof mass and receiver of electrostatic force. Results demonstrate that the free decay rate of the deflected beam is linearly proportional to vacuum pressure. The decay time constant was 0.69 s under low vacuum and 42.56 s under high vacuum. In addition, a change in vacuum pressure of one torr resulted in a change of 47.6 (1/s) in the decay rate. This rapid response to changes in pressure demonstrates the high degree of sensitivity demonstrated by the device. The proposed device represents a considerable advancement in the development of miniature full-range pressure gauges as well as the applicability of micro-electromechanical systems.