Gripping Gecko Secrets Unveiled
Scientists at the University of California Berkeley, have found out how geckos run across walls and ceilings defying gravity. They may have also discovered a novel idea for a new synthetic adhesive in the process.
The speedy geckos, or house lizards, have two million microscopic hairs on their toes and hundreds of thousands of tiny pads called spatulae on the tip of each hair that allow them to dangle effortlessly from a ceiling by just one toe.
"These billion spatulae, which look like broccoli on the tips of the hairs, are outstanding adhesives," Berkeley biologist Robert Full said in a statement Wednesday.
"Geckos have developed an amazing way of walking that rolls these hairs onto the surface, and then peels them off again, just like tape. But it's better than tape."
Talk about walk and go!
Full and Kellar Autumn of Lewis and Clark College in Portland, Oregon and two engineers devised a method to measure the force exerted by the tiny hairs while attached to a surface.
To determine the power when the hairs detached, they used a thin aluminum wire. Their findings are reported in the science journal Nature.
The scientists showed that a single hair could bend the wire or lift an ant. A million hairs covering an area the size of a small coin could lift a child weighing about 45 pounds.
But the researchers said suction alone could not fully explain the adhesive power. They think intermolecular forces that are created when unbalanced electrical charges attract one another to create the powerful adhesion.
Unbalanced electrical charges around molecules attract one another. The charges fluctuate and even reverse, but the net effect is to draw molecules together, such as molecules on a gecko foot and molecules in a smooth wall or ceiling.
The researchers are using their findings to develop a strong, dry adhesive based on artificial hairs similar to those of geckos. They are also looking at a way of studying the force of individual spatulae.
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