Hybrid electromagnetic and electrostatic micromachined suspension with adjustable dynamics

This paper introduces a novel design for a hybrid micromachined contactless suspension, whose operation is based on combining electromagnetic inductive and electrostatic actuation. Wirebonded microcoils provide the electromagnetic inductive actuation, while electrodes patterned on a Si wafer provide electrostatic control. The coil structure and the electrode structure are independently designed and fabricated, and are finally assembled into one device by flip-chip bonding. We demonstrate vertical linear positioning of an aluminium disk-shaped proof mass in a range from 30 to 200 μm based on the coil structure. The electrode structure is employed to dynamically adjust the stiffness components during the operation of the suspension, to control the tilting in a range from ±1° to ±4°, as well as to control the oscillation about the vertical axis with a displacement of 37° at about 1.5 Hz frequency.