Vacuum-gap electrostatic multilayer actuators for space robotics

Abstract

Actuation of space robots poses significant challenges in ensuring operation in vacuum. Conventional electromagnetic technologies face inherent limitations due to heat dissipation and difficulties in lubrication, whereas recent electrostatic alternatives, such as dielectric elastomer actuators struggle to reach their potential due to low reliability and lack of space compatible materials. Here, we introduce a class of electrostatic actuators that leverage the dielectric properties of the vacuum environment and turn it from a limiting factor into a key enabler. These devices rely on dielectric/conductive multilayer thin-film polymeric structures that enclose vacuum gaps, which unimpededly change in volume upon electrical activation, enabling zipping-like motions and generating actuation. Specifically, we demonstrate 0.7 g actuators delivering millimeter-range strokes, forces over 4 N, > 100 Hz bandwidth, and peak power-to-mass ratios of 1.4 kW kg⁻¹. Made from standard space polymers, they enable stackable, power-dense direct-drive actuation in vacuum environments, offering a promising solution for future space applications. The authors report electrostatic actuators that use vacuum to produce strong, fast, millimeter-scale motion by employing space-compatible polymers, representing a promising, compact, and energy-dense actuation alternative for future space robots.