Geckos can run just as easily along a wall or ceiling as they can across a floor. This is due to special pads on their toes, which can even grip glass. No man-made adhesive technology comes even close to functioning as well as gecko feet. And after years of research, the last missing puzzle piece to gecko foot design has apparently been found.
Even though gecko toe pads adhere strongly to almost any surface, they can peel off of those surfaces quickly. That’s because the pads have tiny hair-like projections made from the tough protein keratin that can only be seen at incredibly strong magnification. If the geckos’ feet and tiny keratin fibers got dirty, that sticky interaction wouldn’t work, making them instantly vulnerable to predators.
In an effort to find out how geckos keep their feet clean, researchers based at the University of Akron (UA) found that phospholipids, which are special kinds of thin oils, are manufactured and excreted to keep the keratin hairs clean and serve as the temporary contact adhesive between geckos’ toes and the surface on which they’re walking.
In a study published in Journal of the Royal Society Interface, the team discovered the phospholipids using a technique called “surface-sensitive spectroscopy,” finding the substance as a residue in “the near-invisible gecko footprints.” Before this, phospholipids had not been considered in understanding the self-cleaning and fluid-like ability of gecko feet to adhere and release, according to a UA news release.1 The researchers called the nature of the phospholipids “superhydrophobicity,” which means extremely water-repellent.
An article featured in Nature reported that a separate research group “mimicked pitcher-plant surfaces by making a sponge-like material and filling it with a lubricating liquid to create slippery liquid-infused porous surfaces (SLIPS).”2 The pitcher plant also uses a superhydrophobic lubricant to trap insects that slip on the plant’s surface and fall into its “pitcher.”….
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