Electrostatically balanced comb drive for controlled levitation

An experimental study of the levitation force, normal to the substrate, associated with interdigital capacitor electrostatic comb lateral actuators is reported. For compliant suspensions, normal displacements of over 2 mu m for a comb bias of 30 V were observed. This phenomenon is due to electrostatic repulsion by image charges mirrored in the ground plane beneath the suspended structure. By electrically isolating alternating drive-comb fingers and applying voltages of equal magnitude and opposite sign, levitation can be reduced by an order of magnitude while reducing the lateral drive force by less than a factor of two.<
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