The Self-cleaning Of Gecko Setae And Their Bio-Mimics

Gecko lizards have a remarkable climbing capability that enables them to adapt to a variety of environments.Although the hierarchical structures and adhesion mechanism of gecko feet have been studied extensively,there lacks a fundamental understanding of adhesion at relatively low temperature,in particular below icing point.Here,we study the adhesion forces of nanoscale gecko spatulae and setae on multiple surfaces in a broad range of temperature from 40 to-10?.Results demonstrate that the adhesion force of a single gecko spatula on a mica substrate at-10?increased by¹00%compared with that at room temperature.The adhesion and friction forces of a single seta also display similar trends.It is found that hydrogen bonds play a key role in the temperature-induced tunable adhesion.Emulating gecko feet,we have fabricated fibrillary adhesive surfaces and tested them under different environments.Like their biological counterparts,regulating temperature can tune their adhesion and self-cleaning capacity.However,the poor fatigue resistance of the artificial surface was exposed during the test.The robustness of the bionic surface is improved by gradient doping of Fe₃O₄ nano-powders.This study shed lights on the adhesion mechanism of gecko at low temperature,and provides a base for the design of new generations of smart tires,climbing robots and/or biomedical devices that would perform robustly under extreme environments.