Monday, February 11, 2008

Look out, Spider-Man! Gecko inspires new glue

As reported earlier today, science may have finally caught up with Peter Parker's webbing...

(Link to original article @

It could make you want to climb the walls.

Inspired by the gravity-defying, rapid attach-and-release movement of geckos scampering up vertical surfaces, scientists have invented a non-sticky adhesive that mimics the reptiles’ padded feet and actually gets stronger with use.

The strange material could become the basis for legions of high-speed search and rescue gecko-bots, Band-Aids that finally leave your leg hairs alone, and yes, perhaps even oversized climbing gloves to help you live out your Spiderman fantasy.

The adhesive is fashioned after the foot pad of a diminutive reptile that can go seemingly anywhere.

“For a gecko to move around in the world, it can’t just have Scotch tape on its feet,” said Ron Fearing, director of the Biomimetic Millisystems Lab at the University of California at Berkeley and the co-author of two new studies describing how it all works. “Simultaneously, it’s got to be easy to attach, easy to release, as well as providing enough force to keep the animal from slipping off the surface,” he said.

Meeting all of those requirements without leaving any residue behind is “a completely revolutionary approach to sticking things together,” said Kellar Autumn, a biology professor at Lewis & Clark College in Portland, Ore., and a longtime Fearing collaborator who led the effort to reveal the animal’s unique ability. “We could have the next Mars rover crawling around with gecko feet.”

Inspired by nature
Other groups have found similar inspiration from geckos. Last year, a research team at Northwestern University announced that it had produced a gecko-mussel hybrid adhesive, dubbed “geckel” and deemed suitable for underwater use.

The secret to the gecko’s success is the collective power of tiny forces exerted by millions of odd bristles that extend out from each footpad and then branch into a forest of forked tips. “This is such a bizarre solution that I don’t think engineers would have thought of it if geckos hadn’t evolved it,” said Autumn.

At a microscopic scale, nearly everything in nature is attracted to everything else, and the branching bristles are equipped to take full advantage. The van der Waals forces of attraction, as they’re known, may seem unremarkable to casual observers. “If you put your hand down on a flat surface, there are van der Waals forces holding your hand to that surface,” Autumn said, “but they’re not strong enough to help you climb the walls like Spiderman.”

Ah, but that dynamic would change considerably if your hand was covered in tiny gecko bristles, each brushing up against the wall and helping to build up a considerable attraction.

“Think of Velcro or tape that doesn’t stick until it’s pulled parallel to a surface. But if you relax it, it just lets go,” Autumn said. “That works really, really differently from anything you can find in the store right now.”

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