Analytical models for low pressure square diaphragm piezoresistive MEMS sensor

Abstract

Pressure micro sensors are designed to operate in linear range and presently the most widely used devices are MEMS sensors and have gained popularity in biomedical, automotive and avionics Industries. In the present work modeling of low pressure square diaphragm piezoresistive MEMS sensor has been done using the available analytical models through their best fitting to match with FEM (Finite Element Method) simulation results. This is done for different aspect (thickness (h) / length (L)) ratios of the diaphragm after discovering that the h/L ratio is the prime design parameter. Further, an analytical model for the stress value at diaphragm centre has been proposed whose inevitability is based on the investigation that stress at centre exceeds the stress near the edge of diaphragm with increasing aspect ratios and these values are an important factor for sensor design considering the fact that the level of stress generated in the diaphragm region should be within fracture limit at burst pressure. This work presents analytical models for designing pressure micro sensors applicable to different aspect ratios of diaphragm and thus simplifying the designing of senor without experiencing the limitation of the available models. © 2012 IEEE.