MEMS Acceleration Sensor With Large Dynamic Range and High Sensitivity

This paper introduces a new ultraminiature acceleration sensor with very large dynamic range and high sensitivity. The sensor is based on the concept of creating a variable ultracapacitor structure that consists of one small droplet of electrolyte that is positioned between two carbon nanotube (CNT) electrodes. At rest, the CNT electrodes remain outside of the electrolyte due to their hydrophobic nature. Under acceleration, however, the inertial forces push the CNT electrodes into the electrolyte, and the typical capacitance of an ultracapacitor is obtained. The prototype described in this paper has shown a capacitance variation of approximately 5 mu F under an acceleration increase from 0 to 2200 g. The sensitivity is therefore 2.27 nF/g.