Doubly-anchored thermal actuator having varying flexural rigidity

Abstract

A doubly-anchored thermal actuator for a micro-electromechanical device such as a liquid drop emitter or a fluid control microvalve is disclosed. The thermal actuator is comprised of a base element formed with a depression having opposing anchor. A deformable element, attached to the base element at the opposing anchor edges, is constructed as a planar lamination including a first layer of a first material having a low coefficient of thermal expansion and a second layer of a second material having a high coefficient of thermal expansion. The deformable element has anchor portions adjacent the anchor edges and a central portion between the anchor portions wherein the flexural rigidity of the anchor portions is substantially less than the flexural rigidity of the central portion. The doubly-anchored thermal actuator further comprises apparatus adapted to apply a heat pulse to the deformable element that causes a sudden rise in the temperature of the deformable element. The deformable element bows outward in a direction toward the second layer, and then relaxes to a residual shape as the temperature decreases. The doubly-anchored thermal actuator is configured with a liquid chamber having a nozzle or a fluid flow port to form a liquid drop emitter or a fluid control microvalve, or to activate an electrical microswitch. Heat pulses are applied to the deformable element by resistive heating or by light energy pulses.