Bidirectional, Thin-Film Repulsive-/Attractive-Force Electrostatic Actuators for a Crawling Milli-Robot

We demonstrate a new thin-film electrostatic actuator (RAFA) capable of generating bidirectional repulsive- and attractive-forces. The two-layer actuator controllably produces measured electrostatic pressures up to 156 Pa (38.9 mN, for 2.5 cm
²
electrode area) in repulsion and 352 Pa (88.0 mN) in attraction when operating at 0-1.2 kV. The four patterned electrodes (two per layer) have a cross-section geometry optimized in simulation for maximum blocked force over a 25-500 μm stroke length. RAFAR, a 132 mg milli-robot, uses a 1.45 cm
²
RAFA to crawl at 0.32 mm/s with anisotropic friction feet.