Capturing Bubbles using Aerophilic Surfaces*

When a rising bubble approaches a surface the thin film separating the bubble and the surface drains. If the surface is sufficiently non-wetting, this film will break at a critical thickness and the surface will capture the bubble. In this presentation, we explore the dependency between the ability of a hydrophobic surface to catch bubbles and its texture parameters. We focus on aerophilic surfaces that can entrap a gaseous layer between their textures when submerged, and show how texture parameters affect the dynamics of film drainage. We show how this process can be driven by either bubble deceleration or buoyancy and propose simple guidelines, based on the surface slip length and liquid properties, to determine when the film would drain. We use these findings to design a hierarchical surface with three levels of textures that enable a reduction of two order of magnitude in capture time relative to a flat hydrophobic surface. Finally, we leverage these principles to create an easily scalable device that prevents foam in a passive, and additive-free manner by capturing bubbles as they rise through the bulk of a foaming solution.