A novel dynamic pull-in MEMS gyroscope

The present paper analyzes numerically and experimentally the dependence of the dynamic pull-in voltage amplitude on the values of externally-induced accelerations (e.g. Coriolis accelerations in the case of vibratory gyroscopes). We have investigated the nonlinear dynamic behavior on two different device types, a micro-gyroscope (A) and a micro-accelerometer (B), both fabricated in the SOI-MUMPs process (25 μm thick structural layer). Experimental measurements on the MEMS structures have been performed using Polytec MSA-500 equipment for analyzing the mechanical motion. They indicate that the dynamic pull-in voltages reduce from 100 V to 56 V for device A and from 21.77 V to 17.3 V for device B, for an equivalent acceleration of 0.319 ms-2, when the structures are actuated at their resonance frequency. If the induced acceleration is translated into an equivalent angular rate, _ equivalent, modulating the Coriolisinduced motion, the dynamic pull-in voltages vary from 57.612 V to 56.5 V for device A type and from 20.9 V to 10.75 V for device B type, for a change of 1 rad/s to 5 rad/s in _equivalent.