A bulk micromachined silicon angular rate sensor

We describe an angular rate sensor based on bulk micro-machining of silicon. A silicon beam suspended on two sets of torsion springs has two orthogonal degrees of freedom for angular motion. The Coriolis force induced by external rotation modulates the coupling between the two modes which is then converted to a voltage output by an electro mechanical system operating at the mechanical resonance frequency. The sensor has unique silicon-glass sandwich structures for contacting the electrodes used for electrostatic excitation and capacitive detection within a hermetically enclosed space. The mechanical resonance frequencies are matched by adjusting the effective spring rate with an electrostatic field. The sensor is intended to be used in an automotive control system.