Multiscale Synergistic Gecko-Inspired Adhesive for Stable Adhesion under Varying Preload and Surface Roughness.

Inspired by geckos, fibrillar microstructures hold great promise as controllable and reversible adhesives in the engineering field. However, enhancing the adhesion strength and stability of gecko-inspired adhesives (GIAs) under complex real-world contact conditions, such as rough surfaces and varying force fields, is crucial for its commercialization, yet further research is lacking. Here, we propose a hierarchically designed GIA, which features a silicone foam (SF) backing layer and a film-terminated fibrillar microstructure under a subtle multiscale design. This structure has been proven to have a "multiscale synergistic effect", allowing the material to maintain strong and stable adhesion to surfaces with changing normal pressures and roughness. Specifically, under a high load, the adhesive strength is 2 times more than that of conventional GIA, and it is 1.5 times stronger on rough surfaces compared to conventional GIA. Under high pressure and high surface roughness simultaneously, the adhesive strength is 3.3 times higher compared to conventional GIA. Our research demonstrates that the synergistic effect of multiscale biomimetic adhesion structures is highly effective in enhancing the adhesive strength of GIA under some harsh contact conditions.