Liquid Collection on Welwitschia-Inspired Wavy Surfaces*

The separation of liquids from miscible species (especially those in vapor phase) is of important consequence in myriad processes, notably dehumidification, fog collection, and chemical mist elimination. Most current research incorporates some type of omniphobicity to promote liquid collection, but there exists a lack of universality for surface modifications across a gamut of different working fluids and conditions, including surface tension, supersaturation, and particle size. A difficulty to many existing designs is the struggle to create stable phobicity for low-surface tension liquids and large vapor supersaturations. Here we propose an omniphilic wavy surface design, inspired by Welwitschia mirabilis, that possesses the requisite characteristics for efficient liquid collection: a low energy barrier for nucleation and fast liquid transport.  Utilizing a curvature gradient, liquids on these surfaces experience Laplace-Pressure-driven flow when in the filmwise regime. For both phase-change and isothermal processes, this surface spontaneously refreshes where liquid preferentially deposits by quickly transporting the liquid away to designated locations. We envision that this new surface design can remove the need for stable phobicity, and enable far greater applicability.