High-Output Force Electrohydraulic Actuator Powered by Induced Interfacial Charges

Abstract

Herein, a novel soft actuator design is presented that simultaneously enables a high-output force at a low operating voltage and an adjustable large normal displacement. The electrohydraulic actuator powered by induced interfacial charge (EPIC) uses the amplified electrostatic force when the surface charge-inducing phenomenon of the polyvinyl chloride (PVC) gel and the geometrical gradient of the actuator are combined to reinforce the zipping motion of the liquid layer. This actuator produces a more than 50-fold higher blocking force than conventional dielectric liquid-coupled electrostatic actuators at 2kV. This implies the possibility of expanding the applicability of soft actuators to high-power transducers. This actuator is modeled as parallel capacitors by considering the interfacial-induced charge; the ratio of the dielectric constant of the polymer film to that of the dielectric liquid is analyzed as the principal design criterion for optimizing the performance characteristics. The actuator prototype exerts a force as high as 16 times its body weight (25.5g) and exhibits a large normal displacement of more than 20% of its height (8.5mm). Furthermore, four actuators can lift a weight of 1.25kg and one actuator can be used as a large-aperture (diameter: 30mm) varifocal lens (374% focal length variation).