Adhesive Acrobats: Gecko’s Sticky Feet

Gecko face
Gecko face

One thing I like about visiting the Southwest is getting glimpses of geckos and their reptilian acrobatics on trees and buildings. They can cling to just about anything and support many times their body weight.   How do they do it and what may we learn from it? Most gecko species can defy gravity due to their brilliantly adapted feet. A vertical pane of glass or even a ceiling is no challenge for them. Those little lizards really stick to it!

Scientists and biomedical engineers have been combing through hairy lizard feet for clues to their stickiness since 2000 when University of California researchers pointed to the role of tiny hair-like structures there called setae. How do geckos gain a grip on glass? The cumulative forces of microscopic “flowing locks” put a lock on it. The setae and their little spatula pads form bonds with whatever surface they touch. The firm yet flexible tendons in geckos’ feet help maintain that bond. Contact is broken when the lizards curl their toes to take another step. That rolling motion also helps keep the foot pads clean.

According to the fossil record, geckos have been around for at least 100 million years. They adapted to their environments, on every continent except Antarctica, in unique ways. They are the only lizards with vocal cords and can chirp, click, and send messages to their fellow geckos. In fact, their name derives from gekoq, an Indonesian-Malay imitation of the noise they make. Their eyes are covered with a transparent layer that they lick to keep clean and are exquisitely sensitive to color, even at night.

But it’s their feet that get the most press lately. Who doesn’t want to have gecko powers? We wouldn’t need ladders to wash windows or change a light bulb on the ceiling. What about special gloves for rock climbing or catching balls?  More importantly, we could learn from the geckos how to make products to help injured people, such as a tape that could be used in place of sutures.

Scientists at University of Massachusetts created adhesive Geckskin, named one of CNN’s top five scientific breakthroughs of 2012. At Northwestern University, Professor Phillip Messersmith and graduate student Haeshin Lee created another adhesive material, called Geckel, that can be used wet or dry and has a super strong hold–until you release it. Like a sticky note, it can be used over and over, in this case through 1,000 contact/release cycles.

In addition to applying the principles of gecko feet, the researchers copied the adhesive proteins of mussels that help them anchor themselves underwater. Gecko power plus mussel power made for one mighty strong, reusable adhesive. More inventions inspired by nature, i.e., biomimicry, are sure to come.

Gecko foot
Gecko foot

 

This has been another installment of Ms. Tree’s Nature Mysteries: Adventures in Biomimicry by Barbara Terao.

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