Bioinspired, peg-studded hexagonal patterns for wetting and friction

Inspired by peg-studded hexagonal epidermal cells found in biological pad interfaces, biomimic hierarchical surface patterns with different degrees of wettability were fabricated using a new method involving photolithography and wet etching. In order to understand the effects of the peg-studded structures on wettability and frictional properties, varying patterns were studied and compared. Experimental results show that the hierarchical patterns led to a significant increase in wettability and sliding friction forces on hydrophilic surfaces, whereas they resulted in higher apparent static contact angles and lower sliding friction forces on hydrophobic surfaces. This indicates that the hydrophilic hierarchical structure on smooth toe-pads is favorable for keeping the surface moist and increasing the interfacial friction force when climbing in wet conditions.