Gecko-Inspired 2D Adhesives with Alternating Organogel/Hydrogel Strips Enable Robust and Durable Anisotropic Adhesion

Gecko-inspired surface engineering, from microscale polymer pillars to nanoscale carbon nanotubes, has been scientifically guided by a thorough understanding of the adhesion mechanism of geckos. However, their adhesive performance inevitably deteriorates upon repetitive friction due to the collapse or destruction of 3D micro/nanostructures. Here, inspired by the arc lamellae structures of gecko toes, a 2D organohydrogel adhesive with alternating organogel and hydrogel strips of arc shape (TAS-arc) is demonstrated through a one-step wetting-enabled-transfer (WET) strategy. Independent of any elaborate 3D micro/nanostructures, the gecko-inspired TAS-arc with submillimeter (≈300 µm) adhesive regions realizes excellent anisotropic adhesion performance at optimized friction/peeling directions. Importantly, it can maintain nearly 100% adhesive strength after 1000 friction cycles without apparent structure damage. As a proof of concept, the gecko-inspired 2D TAS-arc is assembled on the tracks of a mobile vehicle, enabling stable climbing on the steep slopes of a PMMA plate. This study offers a unique insight into the development of macroscopic anisotropic adhesives for practical applications.