US Patent 7342346 Microfabricated vertical comb actuator using plastic deformation

A microfabricated actuator of the vertical comb-drive (AVC) type or staggered vertical comb-drive type for torsional or linear applications includes torsion springs which permit self-aligned deformation of the device (micromirror) structure of the actuator through the heating of the torsional springs to plasticity. The torsional springs can include perpendicular-beam springs or double folded beams which allow axial movement of the spring when heated. Heating of the springs can be by bulk heating of the actuator structure or by Joule heating to the torsional springs by passing an electrical current therethrough.