Design, development and characterization of MEMS silicon diaphragm force sensor

Abstract

The aim of the paper is to describe the design, development and experimental characterization of a MEMS silicon diaphragm based force sensor. In the presented design, a unique combination of a thin single crystal silicon diaphragm has been used as a mechanical sensing element. The force sensor is based on the principle of conversion of applied force to an electrical quantity (e.g. voltage) consists of four piezoresistors in a Wheatstone-bridge configuration. The sensor has been modeled with the help of modern CAD tools and, after several iterations, the diaphragm size and thickness have been optimized to obtain a high sensitivity against an applied load in the designed range. The finite element analysis (FEA) has been carried out for computational investigations to have an approximate evaluation in regard of mechanical design and features. The important parameters like stress, strain and deflection are found to be within permissible limits. The fabricated sensor has been characterized by its metrological capabilities. The relative error due to repeatability is found to be <1% in the working range of the sensor. The sensitivity has been found to be in order of 0.35–0.40 mV/V/N for 10 N–50 N force range.