Not even geckos and spiders can sit upside down forever. Nanophysics makes sure of that. Mechanics researchers at Linkping University have demonstrated this in an article just published in Physical Review E. Knowledge that can be of great industrial benefit.
Geckos and spiders that seem to be able to sit still forever, and walk around upside down have fascinated researchers worldwide for many years. We will soon be able to buy smart new fasteners that hold the same way as the gecko's foot. But the fact is, sooner or later the grip is lost, no matter how little force is acting on it. Stefan Lindstrm and Lars Johansson, researchers at the Division of Mechanics, Linkping University, together with Nils Karlsson, recent engineering graduate, have demonstrated this in an article just published in Physical Review E.
Still, it's a phenomenon that can have considerable benefits, for instance in the production of graphene. Graphene consists only of one layer of atom, and which must be easily detached from the substrate.
In his graduation project at the Division of Mechanics, Nils Karlsson studied both the mechanics of the gecko's leg as well as the adhesion of its foot to the substrate. The gecko's foot has five toes, all with transverse lamellae. A scanning electron microscope shows that these lamellae consist of a number of small hair-like setae, each with a little film at the end, which resembles a small spatula. These spatulae, roughly 10 nm thick, are what adheres to the substrate.
"At the nano level, conditions are a bit different. The movement of the molecules is negligible in our macroscopic world, but it's not in the nano world. Nils Karlsson's graduation project suggested that heat, and consequently the movement of the molecules, has an effect on the adhesion of these spatulae. We wanted to do further analyses, and calculate what actually happens," explains Stefan Lindstrm.
They refined the calculat
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