How does a spider stick to the ceiling? According to scientists at the Institute for Technical Zoology and Bionics in Germany, along with a colleague in Switzerland, the spider's secret is all about the van der Waals force, a kind of interaction between individual molecules within a nanometer of each other. Using this simple molecular interaction, spiders can hold up to 170 times their own weight. But there's nothing unique to spiders about this form of adhesion; humans could design objects which take advantage of this molecular-scale force. And it's the potential for biomimicry that makes this discovery particularly compelling.
While the news headlines regarding this research refer to making better sticky notes, the implications are much greater. Van der Waals-based adhesion is not affected by changes in the surrounding environment -- get it wet, expose it to sunlight, get it greasy, and it remains tightly bound. One application that immediately comes to mind for me is remote sensor placement: being able to attach sensing devices to walls, fences, even trees without worry about rain or heat adversely affecting the adhesion seems clearly valuable. More prosaic applications, such as "tape" that can adhere nearly anywhere and doesn't leave residue when removed, also come to mind.
The Eurekalert article gives a good explanation of how this all works, and includes links to six different very high resolution scanning electron microscope images of the foot of the jumping spider species used in the research. The actual article, in the journal Smart Materials and Structures, is also available for the next month.
