Modeling and Experimental Analysis of Low-Cost MEMS Gyroscopes Under PCB Bending Stress

This work is concerned with the examination of one-dimensional stress effects in mode-split, open-loop MEMS gyroscopes with the goal to predict the sensitivity change under printed circuit board (PCB) bending stress. Measurements with ten triaxial gyroscopes are compared to simulation results based on a detailed analytical model. The dependencies of gap distance and overlap of the in- and out-of-plane detection capacitances related to bending stress are formulated. Sensitivity change is predicted with 75% accuracy and the sign of gradient is correct for all measurements. Besides the change in geometry parameters of capacitances the effects of mechanical bending stress on the entire system are discussed. The purpose of the paper is to show the fundamental relationships on which all further considerations regarding MEMS gyroscopes under PCB stress are built.

I. Introduction

Since sensor size and as a result the measured signals are becoming smaller and smaller, environmental influences are having an increasing impact on performance [1]. Further research is necessary to meet demanding specifications in performance stability and robustness [2]. Low-cost MEMS gyroscopes are used in a wide range of applications, for example smartphones, wear- and hearables as well as drones and robotics [3] [4]. It has been demonstrated that low-cost MEMS inertial sensors can be used for inertial navigation with a sensor array reaching position accuracies not too far off from the 1-sigma error prediction due to sensor noise [5].