Adaptive Wettability of a Programmable Metasurface. Issue 2 (28th October 2020) - Specht, Marius
Abstract : Metasurfaces with specific wettability have recently been gaining relevance in numerous areas of science and industry. This hasled to the technical requirements of these functional metasurfaces increasing in cost and complexity. Examples can be found in adjustable filters and membranes, as well as in lab‐on‐chip systems. For a large number of these applications, surfaces with adaptive properties offer unique advantages compared with traditionally engineered systems. Such surfaces with adaptable surface energies, and thus wetting properties, can be realized by either a change in the surface chemistry or structure. Due to novel additive manufacturing methods such as two‐photon lithography, high‐resolution 3D microstructures can be prototypically fabricated and highly specific adjustments of the surface structure can be realized. These advances have enabled a field with particularly broad development possibilities in the area of metamaterials. Herein, a novel mechanoadaptive surface with strain‐dependent wettability states is detailed. The surface was designed, fabricated, and experimentally characterized with a custom test setup that combines the capabilities of contact angle measurements and mechanical straining in one. The results demonstrate a mechanically induced, topologically driven modification of the surface's wetting properties from the hydrophobic to the super‐hydrophobic regime. Abstract : In this article programmable metasurfaces which show an adaptive wettability change as a function of external strain are described. Novel metamaterial unit cells are designed and manufactured on a flexible substrate on micrometer scale. A mechanical deformation of the substrate induces a transformation of the unit cells, which directly leads to a change of the water contact angle from hydrophobic to super‐hydrophobic.