A contact stress sensor based on strain gauge

In this paper a sensor with flexible strain gauge is proposed. The sensor can monitor the contact stress between two surfaces in some extreme environments such as thin slits. The force sensitive element inside the sensor is made up of film grid, supporting layer with holes and deforming layer for smoothing load. The device with this structure can easily convert the positive pressure into pulling stress of film grid. The sensor performance related to the number of holes, thickness of layers and elastic constant of layers is investigated. The response of the sensor is simulated and analyzed with finite element analysis software. Based on simulation results, several parameters are optimized and the corresponding sensor is manufactured. The whole sensor thickness is less than 300 μm. Based on the load test in 0–4 MPa, the results show that the linearity error is ±1.77% of full-scale output (FSO), the average deviation is ±0.98% FSO and the hysteresis is ±0.92% FSO. The proposed sensor has advantages of simple structure, easy package, excellent performance and great practicality.