Close-up of a gecko's legs clinging to a glass surface.
The gecko lizard defies gravity by “sticking” to the surface thanks, in part, to a super-thin layer of fat covering the tips of its legs, shows a study published Wednesday.
Scientists have long been intrigued by the near-supernatural ability of this little lizard, whose secret they have sought to unlock.
They have known for several years that the tips of the legs of geckos are endowed with millions of setules, elastic microscopic hairs, arranged in a certain order and ending in the shape of spatulas.
This microstructure allows it to conform to the shape of the surface on which the gecko is moving. This phenomenon is explained by the so-called van der Waals forces.
We already knew a lot about the mechanical behavior of setules. Now we have a better understanding of how they work at the molecular level, said physicist Cherno Jaye, of the US National Institute of Standards and Technology (NIST), co-author of the study published in the journal Biology letters.
NIST researchers found, using an X-ray microscope, that the setulae and their spatulas were covered with a greasy film one nanometer thick, one billionth of a meter.
These lipids, which protect tissues against dehydration, could also play a key role thanks to their hydrophobic nature. By repelling any water molecules, they would provide the spatulas with closer contact with the surface, said Tobias Weidne, a chemist at the Danish University of Aarhus and co-author of the study, quoted in a statement from NIST. The whole thing would help geckos cling to moist surfaces, he says.
The researchers envisage very concrete applications, via biomimetics, to research concerning the abilities of the gecko .
You can imagine gecko boots not slipping on wet surfaces, or gecko gloves to hold wet tools, said NIST physicist Dan Fischer. And why not, a vehicle capable of traversing a wall, according to him.
Until then, the study concludes that further work is needed to determine exactly usefulness of this lipid film.