MEMS Gyroscopes

MEMS gyroscopes can be easily miniaturized and integrated in the silicon technologies unlike other kinds of these sensors. The integration ease and their low power consumption make them attractive for inertial grade navigation for space application.

The gyroscopes have a tuning fork architecture: two proof masses are forced to vibrate at their resonant frequency,and thanks to the Coriolis force a part of this motion is coupled in the orthogonal axis. This motion can be measured and is proportional to the angular speed of the applied rotation.

The gyroscopes are fabricated on SOI substrates with a thickness of 20 or 60 microns. The devices are patterned on the device layer and released by etching the handle layer. Both the etchings are performed with a Bosch-like process by DRIE (Deep Reactive Ion Etch).

The giroscopes are elettrostatically actuated and measured. The drive and sense motion resonant frequencies are measured, in order to find the dc potential at which the two frequencies are the same. The Q-factor is in the order of few tens of thousands for drive and few thousands for sense.

The gyroscopes exhibit an Allan variance of 7 deg/hr and an angle random walk of 0.018 deg/s1/2.