The Defense Advanced Research Projects Agency is working on technology that could enable soldiers to climb on flat, vertical surfaces, similar to geckos.
The latest development in DARPA's Z-Man program, which aims to develop biologically inspired climbing aids, is a type of adhesive called "Geckskin" that is strong enough to suspend a climbing human.
As with gecko footpads, the secret to the sticking power is van der Waals forces, which are weak attractions between molecules. Creatures such as geckos, spiders and small animals "scale vertical surfaces using unique systems that exhibit strong reversible adhesion via van der Waals forces," according to DARPA.
A gecko's footpad contains thousands of hair-like setae, which become softer in high humidity; this in turn, provides "more surface area for adhesive contact," according to The Journal of Experimental Biology.
Researchers at the University of Massachusetts Amherst used nanofabrication technology to replicate the effect on a human scale. The resulting material can support heavy loads: Researchers hung more than 600 pounds of weight off 16 square inches of Geckskin. It also enabled a 218-pound tester with a pair of Geckskin paddles to climb up and down 25 feet of glass.
DARPA aims to eventually provide the tech to soldiers, so they can climb vertical surfaces built from a variety of materials, all while carrying a full load of combat gear.