How does the gecko climb walls and walk on the ceilings?
Robert Full and Keller Autum have discovered that gecko lizard’s ability to climb up smooth walls and ceilings can be traced to millions of microscopic hairs (as seen above) on the lizard’s toes called “setae”. But without miniature hooks in the walls or ceiling (like in Velcro), what holds the fibers and attached gecko in place? Something called: Static cling!
The fibers in a gecko’s feet are electrically neutral, but the lizard does not need to shuffle across a shag carpet (to get negative charge) to cling to a wall, because he makes use of fluctuations of charge in his setae. The electrons in the fibers in the gecko’s toes are constantly zipping around. Sometimes a few more electrons are on one side of the fiber, making that side slightly negatively charged, while other times a few less electrons are on that side making it slightly positively charged.
If the side of the fiber closer to the wall is, just for a moment, slightly negatively charged, then it will induce a slight positive charge in the wall (by repelling those electrons in the wall close to the surface, exposing the positive charge ions) and an attractive force between the fiber and the wall will result (like the magnets n the fridge). This force is known as the Van der Waals force, and indeed is very weak, and that is the reason why the gecko has millions of these fibers in each toe, so that the total attractive force can be large enough to support the gecko weight.
Scientists today have developed a material that mimic the gecko feet, and can have a number of applications, including feet for wall-climbing robots, and in outer space, where most adhesives don’t work because of the vacuum.
Truth be said, I enjoy a lot writing this post, it is really fascinating how it works.
Bibliography: Physics of superheroes by James kakalios
