Bouncing or sticky droplets: impalement transitions on superhydrophobic micropatterned surfaces

TL;DR

This paper investigates the transition between bouncing and sticking of droplets on superhydrophobic micropatterned surfaces, analyzing forces involved and proposing design guidelines for robust non-wetting states.

Contribution

It introduces a semi-quantitative model linking surface topography to impalement resistance and offers practical guidelines for designing durable superhydrophobic surfaces.

Findings

Identified forces preventing droplet impalement.

Developed a model relating surface features to droplet behavior.

Proposed design principles for robust superhydrophobic surfaces.

Abstract

When a liquid drops impinges a hydrophobic rough surface it can either bounce off the surface (fakir droplets) or be impaled and strongly stuck on it (Wenzel droplets). The analysis of drop impact and quasi static ''loading'' experiments on model microfabricated surfaces allows to clearly identify the forces hindering the impalement transitions. A simple semi-quantitative model is proposed to account for the observed relation between the surface topography and the robustness of fakir non-wetting states. Motivated by potential applications in microfluidics and in the fabrication of self cleaning surfaces, we finally propose some guidelines to design robust superhydrophobic surfaces.