Those of us who are not scientists may not give too much thought when they see a gecko scampering up a wall, but the adhesive forces between that wall and the gecko’s feet have long fascinated scientists. These forces are known as van der waals forces and you may remember learning them in biology class.
Van der waals forces are distance dependent reactions which essentially means that they require the two objects involved in the attraction to be in close proximity to actually work. That is why a gecko must actually touch a wall to climb it. These forces are also pretty weak which is why researchers have seldom had success in giving humans the power of van der waals forces. In order to create apparel that works the same as gecko’s feet do, researchers would have to scale up the magnitude of van der waals forces to accommodate the weight of a human.
On the surface of a gecko’s foot, there are microscopic hairs which are pressed onto a surface thus allowing the lizards to be able to hang on to a wall with only one toe. The forces are strong enough to allow geckos to climb walls but weak enough to allow them to be able to run along walls and let go of surfaces with ease.
The possible applications of these forces range from creating a real spiderman to applying them to robot arms for use in industrial production.
"There are numerous ways that gecko adhesion could be used in an industrial setting, especially in handling delicate materials like the silicon wafers used in manufacturing computer processors," says Michael Varenberg, an assistant professor at GIT.
All of these possible applications sund great, but researchers first need to figure out how to translate a force found in nature, to a human-made, stronger version. Varenberg is currently studying the range of angles that one object could attach to another to maximize the strength of the adhesive force binding the two objects together.
Varenberg’s team found that the optimum range of attachment angles is approximately 60 through 90 degrees. The forces, moreover, do not function (meaning it takes 0 newtons of force to detach) at a range of 140 through 160 degrees.
"That relatively wide range to control the attachment and pulling away for these wall-shaped microstructures will make it easier to build a mechanical process around that tolerance," told Varenberg.
These breakthroughs in the understanding of van der waals forces could hold promise when it comes to the application of these forces in industry. New robotic arms that utilize van der waals forces could make easy the processing and inspection of silicon wafers in computer chip production. Currently, robotic arms use ceramic chunks that use electrostatic grippers in order to pick things up. This is inefficient since, soon after installation, the ceramic posts of contact begin to wear down due to the sheer amount of cyclic overload.
"This reality is inconsistent with the cleanliness standards required in the semiconductor industry," Varenberg claimed. "Using gecko adhesion microstructures instead would be better because they do not generate any damage to wafers and do not wear over time."