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 (α) and thickness (t) of the rectangular diaphragm, as well as the distribution, number (n_p) , and length (l_p) 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.