Enhanced Directional Adhesion Behavior of Mushroom-Shaped Microline Arrays

We report directional switchable adhesion behavior inspired by the locomotion mechanism of gecko lizard. The robust mushroom-like polydimethylsiloxane microline arrays are fabricated by using silicon based over-etching process and replica molding. The line gecko patterns attached to the glass substrate exhibit strong shear adhesion forces in parallel and perpendicular directions with respect to the line direction and high adhesion hysteresis property only in the parallel direction. We have explained the directional adhesion behavior of the line gecko pattern by comparing peeling propagation and normal adhesion phenomenon. Then, we have successfully demonstrated silicon wafer transportation with the line gecko pattern by using directional adhesion behavior of the pattern, which is high shear adhesion force and low peeling force in the parallel direction with respect to the line direction.