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

Abstract

The high-temperature pressure sensors have wide applications in aerospace, petroleum, geothermal exploration, automotive electronics, and other fields. However, the traditional silicon-based pressure sensors are restricted to pressure measurement under <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$120~^{\circ }\text{C}$ </tex-math></inline-formula> and cannot be satisfied to measure the pressure of various gases or liquids in high temperature and other harsh environments. This article 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 (Si3N4) membrane, which could avoid the oxidation of graphene in high temperature and increase the temperature tolerance range. The sensor was placed at various temperatures ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~^{\circ }\text{C}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$420~^{\circ }\text{C}$ </tex-math></inline-formula> ) to explore the temperature characteristics, achieving a maximal temperature coefficient of resistance (TCR) of 0.322% <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ }\text{C}^{-{1}}$ </tex-math></inline-formula> . Moreover, the sensor with a 64 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 9\,\,\mu \text{m}^{{2}}$ </tex-math></inline-formula> cavity has a high pressure sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.32\times 10^{-{4}}$ </tex-math></inline-formula> kPa <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}$ </tex-math></inline-formula> , 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 a high-temperature tolerance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$420~^{\circ }\text{C}$ </tex-math></inline-formula> , which provides new insight into fabricating high-temperature pressure sensors based on graphene and creates more applications in different fields.