A directional adhesion model with hierarchical hair structure for Tokay gecko

Abstract

This paper proposes a hierarchical model of the Tokay gecko's (Gekko gecko) setal system. Based on Euler's elastica theory, the inextensible fibrillar model of the seta is established, taking the thousands of terminating spatulae into account. The directional adhesion of the seta with different slanted angle of the adhesive pad and spatula pad is studied. The elastic energy and the binding energy at the detachment point are also calculated to draw the influence of the adhesive pad's rotation. Compared with experimental results, the model proves to be effective in dealing with directional adhesion problem of the G. gecko, with potential application to help design high-performance synthetic directional adhesives. Some preliminary conclusions about the G. gecko's locomotion in detachment are made based on the model as a complement to previous models.