Sticking Around

Microscopic foot hairs keep geckos on their toes

Microscopic foot hairs keep geckos on their toes, to the point where the small lizard can hang on a sheer surface using just one digit. Case Western Reserve University researcher Shihao Hu, PhD, is part of a project looking to replicate properties of those sticky gecko toes to create a stronger, highly reusable adhesive.

As a graduate student at the University of Akron, Hu and colleagues discovered how microscopic foot hairs called setae helped the lizards scale walls and other surfaces. The mechanics of the geckos’ stride, which involved the animals hyperextending their toes, kept the tiny hairs clean, allowing the footpads to retain their adhesiveness.

“Self-cleaning properties let the gecko stick to surfaces with everyday contaminants and debris,” says Hu, now a postdoctoral macromolecular science and engineering researcher at Case Western Reserve.

Each microscopic foot hair is split into hundreds of even tinier nanobranches. This gives gecko footpads numerous real contact points that collectively generate a formidable force when the creatures flatten their feet and place them onto a surface. Humans don’t have those special hair structures, hence less contact points—and no ability to clamber up walls like Spider-Man.

Even so, Hu’s research has multiple practical applications. He is developing gecko-inspired carbon nanotubes, a strong material that could function as an adhesive in the extreme conditions of outer space.

“It can be used as a glue and won’t leave residue,” says Hu. “You can stick it on a surface then peel it off numerous times.”