The method geckos use to switch their sticky feet on and off could open the door to clever new adhesives or even robots that could by turns cling to walls or rocky surfaces but then spring away with minimal exertion. A forest of tiny hairs known as setae cover the lizards' feet, and researchers at Oregon State University have figured out how they can toggle the stickiness of those hairs.
Each hair itself uses van der Waals forces - weak forces, at the atomistic level - to cling to the surface the gecko is standing on, though that detail itself was only figured out in 2000. Now, study co-author Alex Greaney says, we know how those forces are controlled by the animal.
"These seta and their hierarchy can deform to make intimate contact with even very rough surfaces," Greaney explains, "resulting in millions of contact points that each are able to carry a small load."
Naturally, it turns out, gecko feet don't stick. However, with the application of a small shear force - what Greaney describes as "the opposite of friction" - the stickiness can be activated. What's particularly clever is how little energy is expended to actually do that.
As a result, scientists are already envisaging new ways to utilize the findings. For instance, while synthetic dry-adhesives are already being experimented on - and used on search & rescue robots needing to clamber securely over rubble and other treacherous surfaces - by better being able to turn their gecko-feet on and off the energy requirements could be cut.
Meanwhile, the amount of energy that can be absorbed and recovered by the flexible hairs could also open the door to robotic feet that can catch themselves if falling, though more research is needed to understand exactly how that takes place.
SOURCE American Institute of Physics
IMAGE Bjørn Christian Tørrissen