Pull-in MEMS Inclinometer

Abstract

A novel MEMS inclinometer is presented in this paper. The sensor uses the pull-in voltages of microfabricated structures as the transduction mechanism enabling a high-resolution, auto-calibrated inclinometer. Pull-in is characterized by the sudden loss of stability in electrostatically actuated parallel-plate actuators and since pull-in voltage is stable and easy to measure, it enables an interesting transduction mechanism. The microstructures have differential actuation electrodes (with a common electrode) resulting in two pull-in voltages that change differentially with applied acceleration. The sensor resolution is defined by the resolution of the measured pull-in, i.e., resolution of the actuation voltage. Experimental results show a sensitivity of 50 mV/º with the resolution of the actuation voltage set below 1 μV using a 24 bits Digital-to-Analog Converter (DAC).