By Rose Eveleth
Posting in Design
Understanding how geckos stick to trees in the rain might help us design bandages that don't slip off when we get wet.
Bandages work great when they're dry - the sticky coating clings to our skin and keeps our cuts dry and clean. But we've all seen what happens what that bandage gets wet. Suddenly, the adhesive sloughs off and the little strip slips away.
But humans, and their cuts and scrapes, aren't the first things in the world to try and stick on something wet. Geckos do it all the time. Using our knowledge of how geckos climb walls, researchers are hoping to improve the stickiness of our own bandages.
When they watched geckos in the lab, they saw that their feet repel a few drops of water. But if you soak the gecko's toes the stickiness seems to slip away. But in the wild, geckos climb on wet trees all the time. This mystery is what they're hoping to unravel.
“We’re gathering many clues about how geckos interact with wet surfaces and this gives us ideas of how to design adhesives that work under water,” Ali Dhinojwala, the chair of the polymer science department at the University of Akron, said in a press release. "Nature gives us a certain set of rules that point us in the right direction. They help us understand limitations and how to manipulate materials.”
To learn about the properties of their feet, researchers are strapping geckos onto a wet surface and watching how their feet cling on. What they found, published in the Journal of Experimental Biology, is that the geckos have teeny, tiny hairs on their feet. Science explains:
Each of these microscopic bristles can split into hundreds of nano-sized tips called septulae. Septulae create so-called van der Waals interactions between their molecules and the molecules of the surface that a lizard is clinging to. Such interactions are normally weak, but because there are millions of septulae on each of a gecko's toes, each tiny bristle adds a small grip, which together creates a secure hold. A million setae, which would fit neatly on a dime, could support the weight of a child.
Now, after examining the tiny hairs on the gecko's feet that seem to help them cling on, researchers have started developing an adhesive that mimics that technique. These bandages could be strong, durable and reusable even when wet.
Here's a video of the researchers explaining their work:
Via: University of Akron
Image: Alexander Mussard
Aug 9, 2012