New capacitive low-g triaxial accelerometer with low cross-axis sensitivity

This work describes a compact accelerometer, which integrates three spring-proof mass systems into a single structure to sense triaxial motion. It has a size of 1.3 x 1.28 mm(2) and an operating range of +/- 1 g. Silicon-on-glass (SOG) micromachining and deep reactive-ion etching (DRIE)-based process are adopted to fabricate this accelerometer with a high-aspect-ratio sensing structure. The accelerometer has an excellent z-axis output sensitivity of 1.434 V g(-1) and a high resolution of 49 mu g Hz(-1/2). The sensitivity and minimum cross-axis sensitivity of the x-axis in-plane accelerometer are 1.442 V g(-1) and 0.03% and those of the y-axis accelerometer are 1.241 V g(-1) and 0.21%, respectively. The new in-plane and out-of-plane accelerometer design exhibits high cross-axis sensitivity immunity, high sensitivity and high linearity suggesting that the triaxial accelerometer has the potential for use in future applications in consumer goods and the cellular phone market.