Design and Implementation of the Sensing Element of the Capacitive Microaccelerometer with a Sandwich Construction Using the Variable Dielectric Displacement Method

A sensitive element of MEMS capacitive accelerometer with a sandwich construction (X axis) using the variable dielectric displacement method is studied in this article. As a result, there is a change in capacitance in the output measuring circuit. The considered model provides high sensitivity to the effects of acceleration, resistance to temperature changes and low residual mechanical stress in the sensing element. Modeling and calculations are performed using the ANSYS and SOLIDWORKS programs. The magnitude of the displacement of the movable mass along the sensitivity axis (X) is 5 times greater than the displacement of the movable mass along the nonworking axes (Z and Y), and the capacitance changes between the electrodes along the X axis are almost 2500 times greater than the capacitance changes between the electrodes along the nonworking axes (Z and Y). The mechanical stress in the sensitive element is significantly less than the silicon tensile strength of 440 MPa under the acceleration (0-30g). Temperature variations in the range from -40 ° C to + 85 ° C resulted in very insignificant changes in capacitance along the working axis equaled 0.0025 - 0.003pF, which indicates the temperature stability of the sensitive element. The analysis showed that the developed and studied model of the sensitive element’s design provides high MMA sensitivity and the stability of its parameters.