Bio‐Inspired Instability‐Induced Hierarchical Patterns Having Tunable Anisotropic Wetting Properties

Abstract

This paper introduces a method for the bottom‐up fabrication of bio‐inspired hierarchical patterns having tunable anisotropic wetting properties. The method exploits the surface instability of bilayers comprising a gold nanofilm attached to a substantially prestretched elastomer substrate. Upon film formation, highly aligned wrinkles spontaneously form on the surface owing to the surface instability driven by the compressive residual stress in the film. Thereafter, uniaxial compressive strain is applied to the film by prestretch relaxation of the substrate, which generates an array of high‐aspect‐ratio ridges on the surface. Consequently, hierarchical patterns comprising unidirectionally aligned ridges covered with wrinkles are obtained. Water droplets placed on surfaces having the aforementioned hierarchical patterns show direction‐dependent contact angles, resulting in elongated shapes, which indicates the presence of anisotropic wetting properties. The magnitude of wetting anisotropy can be tuned by simple control of the applied compressive strain and film thickness.

Fabrication of micro/submicron hierarchical structures on ceramic sheet surfaces combining 2-step imprinting and in-plane compression processes

“…[1][2][3][4][5][6][7] Some studies have also been conducted on the fabrication of lotus leaves-like hierarchical structures. [8][9][10] For ceramics, fabrication of microstructures using self-assembly has been studied, [11][12][13] but it is difficult to freely control the periods and shapes of the micropatterns. And a low-cost fabrication process for ceramics with dualscale micro/nano scale hierarchical structures has not been developed.…”