Effect of residual stress on the performance of self-packaging piezoresistive pressure sensor in wireless capsule

Piezoresistive pressure sensors with excellent performance are widely used in the field of biomedical engineering for measuring pressure, however, residual stress will be introduced in the process of repackaging and effect the performance of the sensor. The effect of residual stress on the repackaged pressure sensor is often neglected, but it will cause errors in measuring physiological signals. In this paper, effect of residual stress on the performance of a self-packaging pressure sensor (SPS) is analyzed by finite element analysis (FEA) and experiments. Through analysis of simulation results and experimental data, the material and structure of SPS are optimized. A reinforced plate is used in the self-packaging structure, which can solve the problem of stress induced by the self-packaging structure. Compared with the ordinary SPS, the effect of the self-packaging structure proposed in this paper is reduced by more than 80%; measurement accuracy of SPS in weak signal detection is significantly improved.