Geckos are known to virtually stick to anything, especially vertical walls and even hang upside down. But for the first time, researchers study the molecular details of the surface chemistry of gecko adhesion that remain largely unknown.
They identified protein and lipid molecules on the surface of microscopic structures in gecko feet responsible for their extraordinary grip. They used a synchrotron microscope powered by a particle accelerator to see these nanometer-thin structures, which can pave the way for better biomimicry and provide new insights into biological evolution.
Scientists Zoom in Gecko Feet to Study Lipid Structures
Researchers from the National Institute of Standards and Technology (NIST) zoomed in for a closer look at the structures in gecko feet called setae that are coated with an ultrathin nanometer-size film of water-repelling lipid molecules, Science Daily reported. They used the high-energy X-rays from the synchrotron to analyze the lipids, showing that they line the surface of the setae in dense, orderly arrays.
Lipids repel water or also known as hydrophobic. Physicist and co-author Tobias Weidner from Aarhus University in Denmark and the team hypothesize that it pushes away any water beneath the spatulae to allow more contact with the surface. This might explain how geckos maintain their grip on wet surfaces.
The setae and spatulae are made up of keratin protein similar to hear and fingernails and are extremely delicate. Researchers showed that these proteins are aligned in the direction of setae which may also help resist abrasion.
Stanislaw Gorb, a biologist and study co-author, from Kiel University in Germany, said that it is fascinating to know that everything in gecko feet is perfectly optimized on every scale, from the macro to micro and the molecular structures. Engineers could use this knowledge to build new technologies, such as gecko gloves that can hold tools even when wet or a vehicle that can run up walls.
The NIST synchrotron microscope analyzed the unique ability of setae to identify the molecules on the surface of a 3D object to measure their orientation and map their position. It is typically used to understand the physics of industrial materials, like batteries, semiconductors, solar panels, and medical devices.
They discussed their findings in full in the study titled "Evidence That Gecko Setae Are Coated With an Ordered Nanometer-Thin Lipid Film," published in Biology Letters.
Gecko-Inspired Adhesives
Geckos have inspired many products today, such as adhesive tapes with setae-like structures. These gecko-inspired adhesives stick to surfaces better than conventional adhesives and also have a mechanism like geckos to easily unstick them.
Using these molecular structures to inspire technologies is called biomimicry. Setae provide sticking power due to their flexible and microscopic contours, while these similar structures also end with the spatulae that make close contact with the climbing surface that create van der Waals forces. To easily remove it, geckos just change the angle of setae to interrupt forces.
Live Science reported that his technology could allow humans to climb walls and glasses by sticking to them. Gecko-inspired adhesives are also used by soldiers and spies to climb walls. Soon, it can be used to make boots for astronauts with better grip when they conduct spacewalks, and also for mechanical grippers that snag debris in orbit.
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