Effect of microstructure on sensitivity of flexible capacitive pressure sensor

Abstract

Flexible pressure sensors have garnered enormous attention in recent years. The sensitivity is the primary requirement for flexible sensors. For flexible capacitive pressure sensor (FCPS), the compressibility of dielectric layer is crucial to sensor performance. In this paper, to investigate the effect of microstructure on sensor sensitivity, several models of FCPS with different types and different sizes of microstructures were constructed. The pressure response and sensitivity were simulated using COMSOL Multiphysics. The results showed that sensors with different types of dielectric layer exhibited linear responses in the pressure range of 0-100 kPa. Among the five different types of microstructures, the pyramid type had better sensitivity (1.47×10 ^-5 kPa ^-1 ). When investigating the effect of micro-pyramid of different heights on sensor performance, five micro-pyramid structures of different heights were constructed. In ensuring that the distance between the two electrodes and the applied pressure are the same for the different height microstructure sensors, the compressibility of the intermediate layer and the effective relative permittivity simultaneously affect the sensitivity, resulting in the sensitivity of sensors with relatively large deformation is lower than that of sensors with small deformation. For double-sided micro-pyramids, the sensitivity of the sensor decreases as the thickness between the upper and lower microstructures increases but the thickness not have much effect on the sensitivity. The simulation results in this paper are a guidance to the design of microstructure capacitive sensors.