High Overload Pressure Sensor Construct With Polysilicon Nanofilm

A high overload pressure sensor is prepared by surface micromachined technology, and its full scale pressure is 2.5 MPa. The structure of the proposed sensor is based on a seal cavity made by sacrificial layer, a deposition of polysilicon nanofilm acts as piezoresistors on the diaphragm. The stress distribution of the diaphragm of the sensor is simulated by the large displacement static analysis and the nonlinear contact analysis. Due to polysilicon high tensile strength and appropriate cavity height, the sensor full scale output voltage and overload capacity is greatly improved. The measured results indicate that the overpressure of the sensor sample is seven times higher than its full-scale pressure, and its full scale output voltage is 362 mV with a supply voltage of 5 V.