Shape memory alloy microactuator having an electrostatic force and heating means

摘要

A microactuator and method of operation is disclosed for use in actuating valves, electrical contacts, light beams, sensors and other elements between different actuation modes. An actuator member comprised of a shape memory alloy layer is mounted on an elastic substrate, and the proximal end of the actuator member is carried by a base. The shape memory alloy material is heated through its phase change transition temperature so that it deforms by changing volume to bend the distal end of the actuator member in a first direction relative to the base. Stress forces in the substrate oppose the bending movement, and when the shape change layer is cooled below the transition temperature the stress forces move the distal in a second direction which returns the shape change layer to its low temperature shape. Electrostatic forces are selectively applied between the actuator member and base for clamping the actuator member in one of its positions. In another embodiment a bistable actuator is provided in which the actuator member can be operated between two stable positions.