Performance Optimization of a Capacitive Pressure Sensor

Abstract

In this paper, the thermo-mechanical modelling of an entire sensor structure, under hydrostatic pressure, is carried out using commercial FEM software COMSOL multiphysics. A comparison of the obtained results with those found in the literature, allows us to corroborate the well-known models. Furthermore, the design of high performance conventional silicon-based pressure sensors for low-pressure biomedical applications has been achieved by optimizing the influencing parameters on the two features mentioned above.For a specific biomedical application, a complete analysis, considering the impact of the device thickness, embedding type and diaphragm material, has shown that the highest performances are reached for a silicon diaphragm thickness of 65μm, a circular shape having a radius of 1750μm and a cavity thickness of 4.6μm. Simulation results show that the sensor under investigation yields a quasi linear response with pressure values lying in the range [0 ÷70kPa]. The pressure sensitivity is about 2 pF/bar, and the thermal drift is about 16 ppm/°C for a temperature range [-20°C÷ 150°C]. The obtained results may well contribute to the optimization of the device’s performances and can provide to the designer several chosen criteria for a given application.