OPTICAL DETECTION OF A PRESSURE MICROSENSOR

Abstract

Microelectromechanical systems technology consists of manufacturing sensors and actuators on a micrometric scale, offering low response time, reproducibility, high sensitivity, and low manufacturing costs. Pressure microsensors have a wide range of applications in various areas, such as the automotive industry, production processes, medical equipment, and as an absolute pressure and vacuum sensor. The pressure microsensor developed is based on piezoresistors diffused on a silicon membrane, obtained by the anisotropic corrosion process. The standard response of the microsensor is electrical, obtained through a Wheatstone bridge circuit, in which the potential difference is a function of the resistance variation of the piezoresistors subjected to pressure. This work focused on the direct determination of the deflection of the membrane under pressure through optical measurements using a Michelson interferometer, thus obtaining a calibration curve (membrane deformation × pressure) providing a potential application as an absolute pressure and vacuum sensor. The experimental results were compared with theoretical and simulated values using the COMSOL Multiphysics simulator. The optical results indicated a linear relationship between membrane deformation and measured pressure, resulting in 3.61 μm/bar. Theoretical and simulated models suggest that the sensor's mounting is between free clamping and fully clamped.