A pendulous oscillating gyroscopic accelerometer fabricated using deep-reactive ion etching

A silicon pendulous oscillating gyroscopic accelerometer (POGA) was fabricated using deep-reactive ion etching (DRIE) and silicon wafer bonding technologies. A POGA is the micromachining-compatible analog of the pendulous integrating gyroscopic accelerometer (PIGA), which is the basis of the most sensitive accelerometers demonstrated to date. Gyroscopic accelerometers rely on the principle of rebalancing an acceleration-sensing pendulous mass by means of an induced gyroscopic torque. The accelerometer is composed of three individual layers that are assembled into the final instrument. The top layer uses wafer bonding of an oxidized wafer to a handling wafer to create a silicon-on-oxide wafer pair, in which the oxide layer provides electrical isolation between the mechanical members and the handling layer. The middle layer is a two-gimbal torsionally-supported silicon structure and is in turn supported by an underlying drive/sense layer. The micromachined POGA operated according to gyroscopic accelerometer principles, having better than milligram resolution and dynamic ranges in excess of 1 g (open loop) and approximately 12 mg (closed loop).