On this bright morning, I am very pleased to draw your attention to the remarkable adhesive qualities of gecko feet:
In 2002, biologist Kellar Autumn at Lewis & Clark University in Oregon discovered that the adhesion came from van der Waals Forces, minute molecular-scale attraction (spider feet work in a similar, albeit simpler, manner). Each gecko foot is covered with millions of tiny hairs, or setae, which branch in to nanoscale tips, or spatulae; each seta is strong enough to lift 20mg. The combined adhesive power of a gecko's four feet is over 90 lbs.Duly impressed, Autumn set out to create a biomimetic structure with similar adhesive capabilities:
In 2003, they managed to create artificial setae with adhesion on the order of 0.5 Newton per square centimeter; their eventual goal is adhesion force equivalent to gecko setae, 10 Newton per square centimeter.
One feature of systems of millions of tiny attraction points is that they can be both incredibly strong and readily detached. A gecko is able to peel its feet up and run at a good clip, or stand still and be nearly impossible to pull from a window or wall. As Autumn suggests, geckomimetic adhesive could be of enormous value in object construction, as the adhesion force could be quite strong. At the same time, being able to simply peel apart components -- with no chemical residue -- would enhance our ability to design for disassembly, an important part of cradle-to-cradle thinking.