Physics behind geckos.

Geckos are reptiles from Gekkonidae Family, generally they are small animals. From all the lizards (Squamata) Gekkos are the most specialized taxa. There are some studies argue that geckos are even more diverse and successful than true Lizards.

Geckos has been developed one of the most effectives and versatile form of adherence to the surface of all the animal kingdom, their feet contains millions of tiny, tiny microfibrils kwon as a setae.
This setae are only  a tenth of a millimeter long. (Half the size of a typical paramecium). each one of this branches into thousands of different endings called spatulae, this spatulae are so small that they can't be seen with visible light, the unique way to see it is under UV light. The average length of this spatulae is 0,2 um.



So, in average,  each of one of a gecko's four feet has almost four billions of. When all of this spatulae are in contact with any surface, they create millions of weak molecular attractions called Van der Walls forces, The way these work is pretty simple, and it works similarly to how you can rub an inflated balloon on your cotton shirt, stick it to the wall (or your hair), and have it stay, held up by static electricity. 

The edges of the spatulae get a random charge, either + or - on the tip. When they come near a surface, it causes a charge separation on the surface, and this makes a small, close-range, temporary attraction, like so:

When you get many of these together, they can form a lattice, and result in an extremely large force. The charges will change over time, but as long as they all change together, the attractive force will remain strong, and thus the gecko will remain stuck to the wall.

This amazing capacity of geckos has been studied and reproduced by scientists and biomechanists.  they build artificially setae in order to create new adhesives, (without toxic materials) and even robots that can climb in a lot of surfaces.