If imitation is the best form of flattery, then geckos should feel honored. Taking inspiration from what it claims are the world’s best climbers, DARPA‘s Z-Man project demonstrated how a human of rather heavy constitution can scale up a vertical wall using nothing other than a pair of paddles.
This equipment isn’t meant just for showing off or for the occasional daredevil stunt. Instead, it is primarily being developed with an eye towards warfare. With the Z-Man project, DARPA is taking cues from mother nature herself in order to learn and improve the tools that, in some cases like this, have not considerably evolved in centuries. Climbers still make use of ropes, ladders, and other tools that do not lend themselves quite easily in stealth or safety.
Gecko’s are great climbers especially on smooth vertical surfaces like glass. So great is their climbing prowess that such a lizard can literally hang for its life with only just a finger adhering to the surface. Inspired by this feat, DARPA began to study the scientific intricacies behind the gecko’s sticky power. It all boils down to microscopic, and even smaller, structures found on the lizard’s toes. In the end, it is really all about physics, particularly van der Waals intermolecular forces, and the shape and size of those tips and not the chemistry between the surface and the tips.
Armed with this knowledge, DARPA set out to manufacture tools that would mimic the gecko’s climbing abilities. However, they naturally ran into an obvious stumbling block. The average human weighs exponentially more than a gecko, 75 kilograms versus 200 grams. And that’s not considering the amount of clothing and equipment that a warfighter would have to carry around. Since minuscule strands cannot simply be embedded into human hands and feet, not that those would do any good anyway, DARPA settled for the next best thing, paddles that are large enough to match the increase in weight of the subject but still adhesive enough to handle both vertical and horizontal forces, so that the climber remains securely stuck even while he removes and reattaches paddles in a climbing motion.
The result is a noteworthy feat of a 218 pound man, around 98 kilograms, plus, at one point, a 50 pound or 23 kilo load, climbing up and down a 25-foot vertical glass wall. And he does so with no help other than from the paddles. Of course, the paddles are hardly finished and don’t exactly look that portable, much less comfortable to use. University of Massachusetts’ Draper Laboratory, which created the paddles for DARPA, are also working on the fabrication technology that will produce similar adhesive for biomedical and consumer uses as well.