The Effect of Piezoresistive Film Parameters on High-Pressure Lubricant Film Measurement Performance and Optimization Design

Accurate measurement of high-pressure lubricant film pressure is essential to detect the lubrication condition. Aimed at measuring gauge pressures from 0 to 60 MPa, this study establishes a simulation model of a piezoresistive film to analyze stress and strain distributions. According to the calculation results, it is revealed that the rectangular pressure diaphragm exhibits a more pronounced stress concentration effect compared with the other geometries, which is particularly suitable for high-pressure measurements. Furthermore, the effect of the main design parameters is analyzed, including the length–width ratio ( $\alpha \text {)}$ and thickness ( ${t}\text {)}$ of the rectangular diaphragm, as well as the distribution, number ( ${n}_{p}\text {)}$ , and length ( ${l}_{p}\text {)}$ of the piezoresistors on the measurement performance. Based on the above research, the optimal design parameters are determined, and a significant improvement in the sensor’s sensitivity and linearity is obtained. Then, a piezoresistive pressure sensor is fabricated using MEMS technology, and a series of lubricant film pressure measurement experiments has been conducted. The experimental results show that the sensor achieves a sensitivity of 3.9848 mV/MPa, with a linearity of 0.56%. Furthermore, it exhibits excellent repeatability, with a repeatability coefficient of 0.3088% and a hysteresis coefficient of 0.462%, indicating high-precision and stable measurements of high-pressure lubricant films. This study contributes to the optimization design of high-performance piezoresistive pressure sensors for high-pressure lubricant film measurements, which also helps in the miniaturized design of the sensor device and integration of multiple sensing units in in situ detection systems.