Finite Element Modeling of the Sensing Element of a Capacitive Differential Accelerometer

In this paper presents the single-axis capacitive differential accelerometer sensing element design calculation using the ANSYS software package. The sensing element spring suspensions have been optimized to ensure a sensitivity of 2 fF/g and a resonant frequency of 9 kHz. The sensing element structure first natural frequency is 9 kHz, which corresponds to the value most in demand in the application. The second natural frequency is 23 kHz higher than the first, which indicates a high stability of the structure to accelerations that do not coincide with the main axis of sensitivity. The paper describes the calculation of the comb-finger structure capacity. The sizes and parameters of the comb-finger structure selection have been made. The calculation is performed for the practical implementation of the sensing element and model settings. The comb-finger structure electrodes pull-in voltage calculation is given. The single-axis design of the accelerometer allows to measure accelerations in only one dimension, which can be a great advantage in applications where high resistance to accelerations with an orthogonal orientation to the main axis of sensitivity is required. In addition, this sensing element can be used for both an accelerometer and an inclinometer. Potentially, this design can be used as part of an accelerometer to control linear accelerations in the range from 0.1 g to 50 g.