The gecko's self-cleaning footpads stay tacky.
A sticky situation with geckos has been resolved. The nimble little reptile's toes are so adherent that it can suspend itself by a single digit, yet its feet never get fouled up with dust. Now, using microscopic silica-alumina spheres, a physicist and a biologist at Lewis and Clark College in Portland, Oregon, have figured out why.
They dusted geckos' feet with the spheres and found that as the reptiles walked, their feet shed the spheres and quickly returned to peak stickiness. The spheres stuck to the surface more readily than they did to the feet because the electrostatic attraction of the surface is greater than the collective attraction of the tiny hairs on the toe pads, explain the scientists, Wendy Hansen and Kellar Autumn. So the pads naturally cleaned themselves as the lizards ambled about.
"It opens up the question, 'Can we repeat this with manmade materials?'" says Daniel Fletcher, a bioengineer at the University of California, Berkeley. A self-cleaning adhesive would obviously be useful, he says. This sort of research, Fletcher adds, might also help people figure out how to thwart infectious diseases by foiling microbial adhesives, such as the one that allows the diarrhea-causing parasite Giardia lamblia to stick to the walls of the intestine.
CREDIT: W. HANSEN AND K. AUTUMN |
