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 sti↵ness 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.