Self-contained hybrid electrostatic-pneumatic actuator for portable haptic applications

Abstract

In this study, we present a millimeter-scale hybrid electrostatic-pneumatic (HEP) actuator that combines electrostatic and pneumatic actuation mechanisms within a concentric coplanar structure. The HEP actuator operates by electrostatically driving an elastomeric membrane, which in turn inflates a pneumatic chamber without requiring any external pneumatic components such as pumps, valves, or tubing. A fabricated device with a 1.7 mm radius demonstrated an out-of-plane displacement of approximately 62 mu m at 300 V. Under a 5 g load and driven at 350 V, 1 Hz, the HEP actuator achieved a displacement of 40 mu m, which is well above the 11.2 mu m human tactile perception threshold, and delivered 7.4 mJ/kg of output energy density and 28.1 W/kg of output power density. These values are sufficient for human tactile perception and demonstrate its strong potential for applications to electronic Braille, portable haptic interfaces, and high-resolution tactile displays.