Geckos have millions of setae, which are microscopic hairs on the bottom of their feet. Each ends with 1,000 even tinier pads. Called spatulae, they’re only 200 billionths of a meter wide - below the wavelength of visible light. During locomotion, the setae split so that billions of spatulae closely contact surfaces and increase surface density, capitalizing on weak but chemically universal van der Waals intermolecular electrodynamic forces for sticking. A million setae, which could easily fit on a dime, could lift a 45-lb child.
Says Dr. Kellar Autumn, assistant professor of biology at Lewis and Clark College, “The van der Waals theory predicts that we can enhance adhesion - just as nature has - simply by subdividing a surface into small protrusions to increase surface density. Basically, Mother Nature is packing a lot of tiny things into a given area. This means we don’t need to mimic biology precisely. These preliminary physical models prove that humans can fabricate synthetic gecko adhesive. The artificial foot-hair tip model opens the door to manufacturing dry, self-cleaning adhesive that works under water and in a vacuum.”
Their mode of locomotion gives geckos one of the best mpg ratings around (moving three times farther per unit of energy than other animals of similar size) so making components with similar surfaces might yield the same effects. The group hopes to use gecko mechanics of locomotion in legged robots that can run and climb.