Scientists are gaining a new idea of ​​the secret of how sticky gecko feet remain

Zoom / Close-up of Tokai gecko toe pads. They have many small hairs on each foot called hairs, each of which is divided into hundreds of smaller hairs called spatulas. These help increase contact with the surface.

Yi Sung

The gecko is famous for being an expert and capable climber sticks to any surface Thanks to the tiny hair-like structures on the bottom of their feet. Along with colleagues in Oregon, Denmark and Germany, researchers at the National Institute of Standards and Technology (NIST) took a closer look at those structures using a high-energy synchrotron, revealing that they are covered in a very thin layer of lipid molecules. Upright, according to a last paper Published in Biology Letters.

These tiny microscopic hairs are called hairs, each of which is divided into hundreds of smaller hairs called spatulas. It has long been known that in microscopic size scales, the so-called Van der Waals forcesThe forces of attraction and repulsion between two dipole molecules become important.

Essentially, the tiny tufts of hair on the feet of the gecko get close to lines in walls and ceilings so that the electrons from the particles of the gecko’s hair and the electrons from the wall particles interact with each other and create electromagnetic attraction. This enables geckos to effortlessly climb smooth surfaces such as glass. Spiders, crickets, beetles, bats, tree frogs, and lizards all have sticky footpads of varying sizes that use these same forces.

Geckos and their unusual feet have long been of interest to scientists. In 2013, for example, scientists at the University of California, Santa Barbara, designed a file Reusable dry adhesive Inspired by the feet of a gecko that sticks easily to smooth surfaces, sticks firmly when pushed forward and glides when pulled back. The secret to this trend was the angle and shape of the semi-cylindrical fibers fabricated in the silicone-based adhesive. Pushing the flat side down produced more surface area for adhesion to a glass surface. Pulling the fibers with the round side down reduced the surface area so the adhesive could slide off easily.

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In 2020, Berkeley Scholars investigate why The toes of a soft-haired gecko only “stick” in one direction. Pull one foot in one direction and the gecko’s toes will stick to the surface. Release the foot and it will “peel” the toes in the opposite direction, although this does not prevent the graceful gecko from moving in any way it chooses. Scientists I found it Geckos can run laterally at the same speed they climb up, thanks to the ability to realign their toes. Having multiple fingers helps geckos adapt to stick to slippery or irregular surfaces. The toes that kept in contact with the surface were able to change direction and distribute the load better. And because the toes are soft, animals can adapt more easily to rough surfaces.

Despite all we’ve learned, little is known about the detailed surface chemistry of gecko toe pads, particularly the patches. So the authors of this latest research paper set out to find out more, with particular interest in the potentially prominent role that water may play in surface adhesion. “A lot was already known about how gels work mechanically,” The physicist said NIST and co-author of Cherno Jaye. “Now we have a better understanding of how it works in terms of molecular structure.”

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According to the authors, recent studies have indicated the presence of water-repellent lipid particles in gecko footprints and gecko matrices (they can also be found in the cuticle of reptiles, arranged in a brick-and-mortar pattern). The National Institute of Standards and Technology (NIST) synchrotron microscope is well suited for taking a close look at molecular structure because it can not only identify molecules on the surface of 3D objects, but also reveal precisely where they are and how they are directed.

This thin film of lipid (only a nanometer thick) may push any water away under spoons, the authors speculate, allowing spoons to make close contact with the surface, helping geckos maintain a grip on wet surfaces. Furthermore, spoons and spoons are made up of the protein keratin, much like the proteins found in human hair and fingernails. The analysis revealed that the keratin fibers align in the direction of the hair, which may be the cause of the abrasion resistance.

Gecko feet have inspired many interesting applications in the past, including the aforementioned sticky tape and adhesive and “sticky“Climbing robot with a prosthetic anchor, and even (I’m not kidding with you) a Strapless bra design. Jay and others. Imagine “gecko shoes” that can stick to wet surfaces, or “gecko gloves” to get a better grip on wet tools as potential applications of their latest research.

“The most exciting thing to me about this biological system is that everything is optimized perfectly on every scale, from the macro to the micro to the molecular,” Co-author Stanislav Sock said, a biologist at Kiel University in Germany. “This can help biomimetic engineers know what to do next.”

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