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For years scientists have been trying to figure out the gecko's amazing ability to climb walls. Geckos can climb vertically up a shiny steel surface. They can even walk upside down on a Teflon surface, which is supposed to be a material that nothing sticks to. How do these lizards do it? Scientists still do not agree, even though they have studied gecko feet for years.

In 1934 a German scientist wondered if the adhesion was caused by electrostatic forces. He performed an experiment that seemed to indicate that was not the explanation. He used X-rays to attempt to neutralize static charges of a gecko climbing a metal wall. The gecko continued to stick to the wall.

Back in 2000 a pair of studies seemed to indicate the geckos use van der Waals forces for their grip. Van der Waals are weak forces between the molecules of surfaces that touch each other. Geckos have very tiny toe hairs called “setae” that allow this super-gripping power. The idea was that molecules in those hairs grip the surface molecules of the material the gecko is climbing.

A 2014 study by Hadi Izadi, a chemical engineer at Yale University, suggests that it may be an electrostatic force after all. Testing the gecko on two different surface materials indicated that geckos have twice the gripping power on Teflon as on silicone rubber. If the grip were from van der Waals forces, it should have been the same on both surfaces. Since the grip was not the same, the researchers believe that van der Waals does not explain it. Then they found that when the gecko's toe pads came in contact with the surfaces, electrons jumped from the gecko's setae to the surface. This created a positive charge on the gecko's foot and a negative charge on the surface. Since opposite charges attract, the researchers concluded that electrostatic force must be how the gecko sticks to the surface.

But wait a minute! Other scientists pointed out that a gecko can stick to bare steel where an electrical charge would not accumulate. So perhaps geckos use more than one method to perform their apparent magic. Brilliant scientists have spent years trying to figure out the amazing ability of these fascinating creatures. Maybe some day they will be able to fully explain what God did in this “dandy design.” Source: Science News, August 9, 2014, page 19.

Picture credits:
Top: http://commons.wikimedia.org/wiki/File:Gecko_on_My_Window_2_(17729540).jpg.
Bottom: http://commons.wikimedia.org/wiki/File:Gecko_Leaftail_1.jpg