FEATURE ARTICLE
How Gecko Toes Stick
The powerful, fantastic adhesive used by geckos is made of nanoscale hairs that engage tiny forces, inspiring envy among human imitators
Kellar Autumn
Geckos can run up smooth walls or cross inverted surfaces with
seeming ease. How do they do it? Author Autumn describes recent
research in his lab and others that tells the tale. It turns out
that gecko toe pads are sticky because they contain extraordinary
structures that act together as a smart adhesive. But gecko toes
work nothing like pressure-sensitive adhesives (found on adhesive
tape), which are soft enough to flow and make intimate, continuous
surface contact. Instead, gecko toes bear ridges covered with arrays
of stiff, hairlike setae. Each seta branches into hundreds of tiny
endings that touch the surface and engage intermolecular van der
Waals forces. Together, the 6.5 million setae on a 50-gram gecko
generate enough force to support the weight of two people.
Furthermore, gecko toes detach within milliseconds, stick to nearly
every material, and neither stay dirty nor self-adhere.
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