Enhanced electro-actuation in dielectric elastomers: the non-linear effect of free ions

TL;DR

This paper introduces a model explaining the non-linear electro-actuation behavior of PVC gels, highlighting the influence of free ions and electro-wetting effects on their deformation, which could lead to advanced soft robotic actuators.

Contribution

It presents a new theoretical model for PVC gel electro-activity, emphasizing the role of free ions and deriving analytical expressions for surface tension and dielectric constant.

Findings

Free ion size critically affects electro-induced deformation.

Electro-wetting influences the deformation behavior.

Analytical expressions for surface tension and dielectric constant are derived.

Abstract

Plasticized poly(vinyl chloride) (PVC) is a jelly-like soft dielectric material that attracted substantial interest recently as a new type of electro-active polymers. Under electric fields of several hundred Volt/mm, PVC gels undergo large deformations. These gels can be used as artificial muscles and other soft robotic devices, with striking deformation behavior that is quite different from conventional dielectric elastomers. Here, we present a simple model for the electro-activity of PVC gels, and show a non-linear effect of free ions on its dielectric behaviors. It is found that their particular deformation behavior is due to an electro-wetting effect and to a change in their interfacial tension. In addition, we derive analytical expressions for the surface tension as well as for the apparent dielectric constant of the gel. The theory indicates that the size of the mobile free ions has a crucial role in determining the electro-induced deformation, opening up the way to novel and innovative designs of electro-active gel actuators.