60-Second Science

Tiny Toe Tools Ensure Gecko Traction

To activate or loosen their grip on a surface, geckos extend and angle or retract tiny toe hairs that create contact points. Clara Moskowitz reports 


As is well known, geckos sell car insurance. But they’re also famous for their extremely adhesive feet, which can keep them stuck to walls and even ceilings. Archimedes wondered how they do it. Geckos can also easily loosen their grip and break into a dash, which has flummoxed physicists. But scientific stick-to-itiveness finally found the on/off switch.
Geckos’ toes are covered in thousands of tiny hairs called setae. These setae can bend to make contact with all the grooves and crevices in a surface. To adhere, the setae rely on small electromagnetic attractions between molecules called van der Waals forces.
Researchers created mathematical models that revealed that the default for gecko feet is non-sticky. To activate the grip, the lizards extend and angle their setae to create millions of contact points with a surface. The research is in the Journal of Applied Physics. [Congcong Hu and P. Alex Greaney, Role of seta angle and flexibility in the gecko adhesion mechanism]
Scientists would love to create synthetic adhesives based on the gecko trick. Perhaps by harnessing the power of setae, robots could climb walls, and stick or unstick without expending much energy, just as the gecko does.
—Clara Moskowitz
[The above text is a transcript of this podcast.]

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