On the role of the van der Waals interaction in gecko adhesion: A DFT perspective

Abstract

The significance of the van der Waals (vdW) interaction in the adhesion mechanism of geckos to surfaces is estimated quantitatively using dispersion-corrected density functional theory (DFT). A complete survey of the pairwise energies for the elements present in gecko epithelia, soda lime glass and polytetrafluoroethylene (PTFE) shows that the van der Waals interaction plays a minor role in the binding between the atoms in the epithelia and the glass and PTFE substrates. Using a simplified microscopic model for the geckos epithelium, DFT predicts strong (weak) binding between the gecko and glass (PTFE) surfaces, both with and without the vdW interaction. This is in agreement with experimental observations, and is highly suggestive that dispersive interactions only play a minor role in gecko adhesion to glass and PTFE surfaces.