Differential MEMS capacitance diaphragm vacuum gauge with high sensitivity and wide range

Abstract

MEMS vacuum gauges have received a great deal of attention in recent years. In this paper, a MEMS capacitance diaphragm vacuum gauge with high sensitivity and wide range is designed for differential pressure measurement. A novel circular silicon diaphragm is used as the pressure-sensing diaphragm of the gauge. The diaphragm has a large radius-to-thickness ratio of 283 and works in touch mode. The design principle of the gauge is introduced in detail, and the finite element software is used for simulation analysis. Based on the techniques of microfabrication, a prototype of the gauge was fabricated, and its performances were investigated using a differential vacuum system. The results show that the MEMS capacitance diaphragm vacuum gauge, having good stability and repeatability, is capable to measure differential pressure from 0 Pa to atmospheric pressure. The capacitance-pressure curve is piecewise linear, with the maximum sensitivity of 26 fF/Pa in the low range and the minimum sensitivity of 0.8 fF/Pa in the high range.