Finally!!!!!! Scientists have finally discovered the secret of GECKO TOES!!! Yup...that's right...that nagging question that's been keeping us all awake at night is answered. No longer do we need to toss and turn while pondering how those darn lizards can walk upside down.
The answer lies in hairy toes and van der Waals forces. Nope, it's nothing to do with Lord of the Rings and hobbits. It seems that geckos have millions of tiny tiny hairs on the bottom of their feet. Each of these hairs is smaller than a human hair AND each of these teeny weeny hairs splits into 1,000 tips. These tips are so small that they can only be seen by using a electron microscope. Wow...talk about split ends!! These tips are so small that they are affected by the van der Waals force...or that weak attraction between individual molecules. Each molecule of the gecko's toe hairs is attracted to molecules in the surface that it touches. That small attraction multiplied by thousands of split ends on millions of hairs on each foot is what makes it possible for the gecko to stick to walls, ceilings and even glass. What's even cooler is that the shape of the hair tips is such that the gecko can move really fast, sticking to surfaces in less than one eight-thousandth of a second and unsticking in half that time.
So, enquiring minds want to know...How did scientists figure all of this out? Well..I'm going to tell you. This puzzle has been bothering people since way back, back in the fourth century BC when Aristotle observed the sticky lizards. For the past century or so, since Dutch physicist Johann van der Waals won the Nobel Prize in physics 1910 for his research on the gaseous and liquid states of matter, studies have attempted to figure it out. Earlier studies had figured out that the adhesion was either due to the capillary effect of tiny amounts of water that create suction or to something that worked in the absence of water as well, such as van der Waals attraction. Those smart folks at Berkeley and Stanford tested this by manufacturing synthetic gecko hairs and testing them on two types of materials, one that allowed the capillary effect, and one that didn't. The fake hairs stuck to both materials. Water wasn't required it seems, so the solution was in hand. There was much rejoicing.