A piezoresistive pressure sensor with centralized piezoresistors and a diamond-shape composite diaphragm

Abstract

In this paper, a piezoresistive pressure sensor with centralized piezoresistors and a diamond-shape composite diaphragm was presented, which was mainly composed of a silicon on insulator (SOI) layer for pressure sensing and a glass layer for hermetic packaging. Different from conventional counterparts, in this study, among four piezoresistors of the Wheatstone bridge, two were positioned at the center while the other two were positioned at the edge of the pressure-sensitive diaphragm, producing a higher sensitivity and a lower nonlinearity when the thickness of piezoresistors was taken into consideration. Based on finite element simulations, the structure of the pressure-sensitive diaphragm was optimized by an evolutionary method with maximum degrees of freedom, producing a unique diamond-shape composite diaphragm where the corresponding maximum stress was 74% higher than the flat counterpart under the same deformation. From the experimental results, the fabricated pressure sensor reported a high sensitivity of 87.5 mV·V−1·MPa−1 and a low nonlinearity of 0.03% FS at 20 °C, and an accuracy of better than 0.04%FS from − 40 to 140 °C, which may function as an enabling tool in pressure measurements.