A method of performance enhancement for piezoresistive pressure sensors through diaphragm size design

Abstract Sensitivity and nonlinearity are two of the most basic and important properties of microelectromechanical systems piezoresistive pressure sensors. In this paper, we proposed a simple method to enhance sensor performance by changing the diaphragm size, which can improve both sensitivity and linearity. To obtain close sensitivity for different diaphragms, we first fixed the ratio of the edge length to the thickness of the diaphragm. Then, the relationship between sensitivity, linearity, and diaphragm size was established by calculation, and the simulation was carried out using ANSYS. We found that both sensitivity and linearity increased with an increase in the diaphragm side length. In addition, we designed and fabricated two pressure sensors with square diaphragms in the range of 30 MPa. They have the same length-to-thickness ratio of 3.33, and the edge lengths of the diaphragms are 346 μ m and 599 μ m, respectively. The test results showed that the device with a larger edge length had higher sensitivity and lower nonlinearity, which is consistent with the conclusion above. Therefore, increasing the diaphragm size may be an easy and practical way to improve the performance of the pressure sensors.