Wet, Hydrophobic Surfaces Give Geckos Secure Grip Too

Scientists found that wet surfaces provide as much of a strong grip for geckos as dry surfaces.

Scientists have often wondered how geckos manage to climb wet surfaces and not slip off. They have finally been able to resolve the prolonged mystery through a study that was conducted recently. A group of University of Akron researchers found that wet, water-repellent surfaces like those of tree trunks and leaves secure a gecko's grip similar to the way dry surfaces do.

This discovery could help UA integrated bioscience doctoral candidate Alyssa Stark and her research colleagues in developing an adhesive that sticks when wet.

Geckos have small, clingy hairs on their paws that stick like glue to dry surfaces. In 2012, a study was conducted that provided evidence that geckos lose their grip on wet glass which made scientists wonder how they climbed leaves and tree trunks that were wet.

For the study, six geckos which had harnesses around them were analyzed for their gripping power. The harnesses were gently tugged at as the lizards clung to surfaces in wet and dry conditions. Researchers found that a geckos grip was influenced by the surfaces wettability, which is the ability of a liquid to maintain contact with a solid surface. Glass has high wettability and the film of water that forms on the glass comes between the gecko's feet, decreasing adhesion.

"The geckos stuck just as well under water as they did on a dry surface, as long as the surface was hydrophobic," Stark explains. "We believe this is how geckos stick to wet leaves and tree trunks in their natural environment."

The study titled "Surface Wettability Plays a Significant Role in Gecko Adhesion Underwater," was published by the Proceedings of the National Academy of Sciences Monday.

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