Thin-film repulsive-force electrostatic actuators

Abstract We demonstrate thin-film repulsive-force electrostatic actuators that employ a new electrode pattern and are useful for low-force actuation applications. Compared to prior patterns, the new electrode geometry increases electrostatic force production by an order of magnitude (at equal voltages) and eliminates the most common shorting failure modes. These electrostatic actuators have stable open-loop operation with no pull-in instability, low mechanical hysteresis, and peak force in rest configurations. The actuators are fabricated with a planar, flex-circuit manufacturing process, allowing production at scale and over large areas. Two-layer out-of-plane linear actuators (25 × 10 mm electrode area) were characterized: with 0–1000 V inputs (40 × 10 6  V/m), blocked normal forces of 9.03 mN (36.1 Pa) were generated, and controllable linear displacements up to 511 μm were measured across an open loop bandwidth of 43 Hz. Finally, we present a 290 mg 1-DoF micro-mirror system for laser beam steering that employs a two-layer out-of-plane rotational actuator for open-loop stable operation with controlled angular displacements up to 5.1° at 1000 V/16 Hz.