A Novel High-temperature Pressure Sensor Based on Graphene Coated by Si3N4

The high-temperature pressure sensors have wide applications in aerospace, petroleum, geothermal exploration, automotive electronics and other fields. However, the traditional silicon pressure sensors are restricted to pressure measurement under 120 °C and cannot be satisfied to measure the pressure of various gases or liquids in high temperature and other harsh environments. This paper proposes a novel high temperature pressure sensor based on graphene, in which a rectangular cavity is applied to improve the piezoresistive characteristics of the sensor. The unique of this sensor is that the graphene is coated by the silicon nitride (Si 3 N 4 ) membrane, which could avoid the oxidation of graphene in high-temperature and increase the temperature tolerance range. The sensor was placed at various temperatures (50-420 °C) to explore the temperature characteristics, achieving a maximal temperature coefficient of resistance (TCR) of 0.322% °C -1 . Moreover, the sensor with a 64×9 μm 2 cavity has a high pressure sensitivity of 5.32×10 -4 kPa -1 , enabling a wide range from 100 kPa to 10 Pa. Experimental results indicate that the proposed sensor possesses superior pressure sensitivity, a wide pressure detection range and high-temperature tolerance of 420 °C, which provides new insight into fabricating high-temperature pressure sensors based on graphene and creates more applications in different fields.