Electrically Modulated Wetting of Drops on Soft Dielectric Films

TL;DR

This paper investigates how the elasticity of dielectric films influences electrowetting behavior, revealing that softer films enable additional control over droplet manipulation, with implications for soft lenses and drug delivery.

Contribution

It introduces the effect of dielectric elasticity on electrowetting, extending the classical paradigm and explaining surface deformation due to electro-elastocapillary interactions.

Findings

Elasticity modifies electrowetting behavior.

Soft dielectric films allow enhanced droplet control.

Deformation profiles are explained by electro-elastocapillary effects.

Abstract

The inter-connection between the elasticity of a dielectric film and the wetting of a sessile drop on the same, under an applied electrical voltage, remains unaddressed. Here, we report the electrowetting-on-dielectric (EWOD) behaviour of sessile drops on dielectric elastomer films of varying elasticities- from an apparently rigid dielectric film to a soft, deformable dielectric film. Our results reveal that the elasticity of the underlying dielectric film provides an additional control over the droplet electrowetting behaviour, which may be best addressed from free energy based consideration, leading to a modification of the classical Lippman-Young paradigm. We also provide an explanation on the displacement profiles for the deformation of the soft dielectric surface, due to the interfacial electro-elastocapillary interaction triggered by the electrowetted sessile droplet. These results can be of profound importance in various emerging applications, ranging from the development of soft liquid lenses to drug delivery.