# Behaviour of flexible superhydrophobic striped surfaces during (electro-)wetting of a sessile drop

## TL;DR

This study investigates how elastic superhydrophobic striped surfaces deform under different wetting conditions, revealing the importance of non-linear modeling for accurate predictions of lamellae deformation during electrowetting.

## Contribution

It provides experimental measurements and a theoretical framework showing the dominant role of capillary forces and the necessity of non-linear analysis for elastic lamella deformation.

## Key findings

- Deformation profiles are mainly controlled by horizontal capillary forces.
- Electrowetting indirectly influences lamella deformation.
- Non-linear models are essential for accurate deformation predictions.

## Abstract

We study here the microscopic deformations of elastic lamellae constituting a superhydrophobic substrate under different wetting conditions of a sessile droplet using electrowetting. The deformation profiles of the lamellae are experimentally evaluated using confocal microscopy. These experimental results are then explained using a variational principle formalism within the framework of linear elasticity. We show that the local deformation profile of a lamella is mainly controlled by the net horizontal component of the capillary forces acting on its top due to the pinned droplet contact line. We also discuss the indirect role of electrowetting in dictating the deformation characteristics of the elastic lamellae. One important conclusion is that the small deflection assumption, which is frequently used in the literature, fails to provide a quantitative description of the experimental results; a full solution of the non-linear governing equation is necessary to describe the experimentally obtained deflection profiles.