intimate surface contact?

for you on v-day--geckos!

[article apparently published in the sigma xi newsletter (wha?) and courtesy of ms. d.]

How Gecko Toes Stick
Nanostiff, microsquishy hairs engage tiny forces to create a powerful adhesive.

Geckos can run up walls or cross inverted surfaces with seeming ease. How do they do it? In the March-April American Scientist magazine, Lewis & Clark College biologist Kellar 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. Autumn is currently collaborating with engineers to design legged robots that can run up walls.