Anti-fouling characteristics of super-wicking surfaces inspired by cornea

Super-wicking surfaces have been highlighted owing to their excellent water-spreading properties that enable anti-fouling features for various potential applications. The animal corneal surfaces consist of the open-type microchannels, on which nanostructures are uniformly covered, generating effective tear spreading characteristics. Herein, we demonstrate facile fabrication of the super-wicking surfaces on the stainless steel surfaces, inspired by the corneal surface. Specifically, the open-type microchannel networks are formed by selectively etching the grain boundary of the metal surfaces through an electropolishing process. Then, the uniform chromium oxide crystalline layer, including chromium manganese spinel, is generated by out-diffusing chromium and manganese ions from the stainless steel substrates through the thermal oxidation optimized to suppress ferrite breakaway oxidation and chromium carbide formation. The resulting outcomes not only include the excellent water spreading properties of the fabricated surfaces but also decrease the scale formation of bare surfaces by -78 % in channel-flow, scale-precipitating experiments.