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.