Gecko glue may give drivers the brake they’ve been looking for
Posted by Miqe on June 17, 2007
THE gecko is well known for its adhesive acrobatics and wall- and ceiling-scaling techniques.
Now this small, pretty lizard is helping scientists out of a sticky situation of their own.
Recent studies of the gecko’s spatula-tipped toe hairs, called setae, have revealed the secret behind the lizard’s uncanny sticking power – a quick-release mechanism that allows it to stick to surfaces.
Geckos can walk upside down on glass and smooth concrete, for example, without the aid of liquid or surface tension and then detach with minimal effort.
Researchers in the US say they can use this mechanism to manufacture advanced car braking systems that could stop a car travelling at 80kmh in a distance of just five metres, using only a third of a square metre of this reptilian “glue”.
A BBC documentary on this research suggested artificial gecko hairs could revolutionise how tiny things are stuck together and have uses in microsurgery and computer chips.
Robots with synthetic gecko feet could help in search and rescue missions and in space.
Geckos are already evolutionary wonders. They are the only lizard to make chirping sounds in social interactions with other geckos. When cornered, they can expel a nasty-smelling substance and faeces onto their attacker.
Some species are even parthenogenic, meaning the female doesn’t require the services of the male to reproduce.
Gecko stickiness is unlike any conventional adhesives, which often stick with ease but only detach with a great amount of force (as anyone who has tried peeling off those plastic wall hooks will tell you). By contrast, research has proven that gecko foot hairs adhere strongly and detach easily.
The attractive force that holds geckos to surfaces is a product of intermolecular interactions between the extremely fine and numerous setae on its toes (almost 500,000 on each foot) and the surface itself.
But the real trick, it seems, is some clever trigonometry on the part of this extraordinary creature.
Biologist Dr Keller Autumn, of the Lewis and Clark College in Oregon, and his colleagues were the first to look at the actual force that was required to detach gecko hairs from a surface, and how this force changed in relation to the angle at which it was applied.
For example, Autumn and his team found that when the hairs lay at an angle of 30 degrees to the surface, the gecko could resist weights up to 130kilograms, but at angles of more than 90 degrees the hairs would begin to peel off.
Due to the solidity of each seta, not a single one was damaged in this process, allowing the gecko a lifetime of Spider-man-like agility.
Autumn has no doubt the principle of gecko adhesive could solve a number of problems and, potentially, be used in car braking systems.
He told New Scientist magazine: “It’s such a bizarre solution to an engineering problem. No one would have ever thought of it if it hadn’t evolved in geckos.”
But don’t rush to the car parts store just yet. It could be at least 10 years before gecko glue becomes a viable option in automobile safety.
“Scaling things up creates big problems,” Autumn said. “We know it’s a challenge none of the virtual gecko adhesives are capable of doing.”