How does ‘Gecko tape’ work?

Abstract

Human-made adhesives lose their tack rapidly after first use, while animals such as geckos can reuse their adhesive feet for a lifetime. Nature's use of fibrillar structures as strong, renewable and self-cleaning adhesives has inspired the development of synthetic adhesives with similarly structured surfaces. More than a decade of research and engineering has culminated in ‘gecko tape’: a re-useable adhesive that has a structured surface similar to that of geckos and that outperforms the usual sticky tape. We report experiments that show that, despite its name, a commercial gecko tape shares few adhesive principles with its eponym. In particular, we find no evidence that the micrometric features that are present on the surface of the gecko tape play a role in its adhesive strength. In addition, we find that contrary to the gecko, the tape leaves behind a layer of adhesive after removal from the surface. The fact that the gecko tape outperforms a conventional adhesive tape is due to the fact that the softness of the backing of the gecko tape allows to create a much larger contact area for a given normal force. The conclusion is that surface features are not necessary to create a superb adhesive; tuning the backing layer elasticity may be enough.