Analysis on edge effect of MEMS capacitance diaphragm gauge with square pressure-sensing diaphragm

For high-accuracy MEMS capacitance sensors, the edge effect of capacitance cannot be ignored. This paper introduces a MEMS capacitance diaphragm gauge with a square pressure-sensing diaphragm for 1–1000 Pa measurement. The edge effect is analyzed using integrated method and conformal transformation theory. FEM software is used to calculate the capacitance and sensitivity of the MEMS capacitance diaphragm gauge. The results show that the edge effect is weakened with the increase of 2a/d (the ratio of the length 2a of the diaphragm and the depth d of vacuum gap). And the thickness t of the diaphragm also has a positive contribution to the edge effect. With optimization of the diaphragm and vacuum gap design, the capacitance error caused by the edge effect is 2.2%, meanwhile, high sensitivity and good linearity can be kept.