Design and simulation of ultra high sensitive piezoresistive MEMS sensor with structured membrane for low pressure applications

In order to increase the sensitivity of a piezoresistive pressure sensor, the membrane needs to be very thin or very large to achieve good results. But there is a trade-off between stability, linearity and sensitivity. The thinner the membrane, the more instable is the sensor structure. The original sensor developed for wall pressure measurement has a membrane thickness of 4 μm. The herein presented idea is to use partly-structured thicker membranes to improve the sensor performance. In this paper we show the optimization of the new sensor structure by using DoE (Design of Experiment) and FEA with ANSYS software. Due to the optimized membrane structure, the sensor sensitivity could be increased up to 300% in comparison to sensors using unstructured silicon membranes.