New non-slip material
Gecko feet served researchers at the University of California in Berkeley led by Ronald Fearing as a model for a new, very non-slip material. Applied to the surface of a coin, it prevents it from sliding off a nearly right-angled glass plate without sticking it. Unlike gecko feet, however, the effect is not based on adhesion but on friction.
The new material consists of vertical, microscopic plastic fibers made of polypropylene, of which there are 42 million per square centimetre. The individual fibers are only a hundredth the thickness of a human hair and are 0.02 millimeters long.
The diameter of the synthetic fibers roughly corresponds to that of the finest structures at the end of the hairs under the feet of geckos. With the help of these structures, the reptiles are also able to cling to smooth surfaces upside down – whereby the tiny hairs do not get caught in small bumps, but enter into the weakest known type of molecular interaction, the van der Waals interaction. The van der Waals forces only come into play when there is very close and sufficient surface contact. The artificially produced fibers do not adhere because they are too rigid to be able to make the necessary surface contact.
Soft, elastic materials such as rubber are usually used as non-slip materials. However, they tend to be sticky - unlike the propylene fibers. The researchers want to further develop the fibers in such a way that, in addition to friction, they stick like gecko feet and can be detached again without leaving any residue.
