Author(s)

K. Takahashi

Abstract

Creatures such as geckos have a multi-hair structure on their foot surfaces to adhere to roof surfaces without any slimy secretion. The effect of the surface roughness on the adhesion force is analysed theoretically based on contact mechanics considering observations. The foot hair has some compliance and is derived to be suitable to grip rough surfaces quantitatively. The surface roughness decreases the adhesion force, however the compliance recovers it. The effect of the roughness and the compliance on the adhesion force is analysed theoretically and discussed quantitatively. We have clarified a mechanism of the geckos to release surfaces to take a quick step with such adhesive feet. The analysis gives a lot of significant knowledge to design or mimic the function of the creatures such as geckos. Keywords: adhesion, detachment, surface roughness, JKR contact, gecko, grip and release, attach and detach, manipulation, roof-hanging, wall-climbing. 1 Introduction The climbing ability of geckos attracts the interest of scientists [1,2]. The geckos have about a hundred billion setae per square meters on their foot finger surfaces. Plenty of nano-scaled spatulas at the top of the setae generates adhesion force, so that they can grip the roof surfaces to hang their weight. The compliant setaspatula structure is believed to be for the purpose of gripping rough surfaces. However, the effect of the roughness and the compliance on the adhesion force has not been expressed clearly. Micro-fabricated adhesives mimicking the gecko foot hair are reported [3, 4]. They are just like tape, so sometimes they are called \“gecko tape”. We cannot simulate the gecko’s quick step using these adhesives. There must exist some

Keywords

adhesion, detachment, surface roughness, JKR contact, gecko, gripand release, attach and detach, manipulation, roof-hanging, wall-climbing.