Darpa technology lets people climb walls like geckos

Researchers used the technology from Darpa’s Z-Man project to have a man weighing just under 100 kilograms climb a 7.5-meter glass wall. During the ascent, the man only made use of panels inspired by the legs of geckos.

It is known from previous research that the legs of geckos have a stiff, yet flexible, hair-like structure called seta. The hairs on geckos’ feet are said to be about 0.1mm long and 0.002mm thick, giving the critters the ability to stick to surfaces that normally wouldn’t stick. Van der Waals forces are used for this. In areas with high humidity, the hair-like structure softens, providing a larger adhesive surface.

The researchers managed to replicate this structure with existing raw materials and incorporated it into what they call ‘geckskin’. For this they have used rigid materials such as carbon fiber and Kevlar in combination with flexible materials such as polyurethane and polydimethylsiloxane. According to the researchers, the combination of these materials allows the geckskin to spread out optimally over a surface, resulting in a larger adhesive surface. A piece of geckskin measuring 16 square inches, converted about 103cm², has previously proven to be able to carry almost 300kg.

The researchers attached this technology to special panels that allowed a man weighing just under 100 kilograms to climb a 7.5-meter vertical glass wall. One of the challenges for the team of researchers with these panels was that the whole thing had to stick to the wall enough, but not so much that it would then be difficult to peel off. In the test with static weights this problem was not an issue. It would have been overcome with the panels, indicating that the composition of geckskin is not adapted for the climb.

The technology is designed for soldiers who until now have used ladders and ropes to climb on or over a high object. Disadvantages of this include that soldiers can only venture up a climb one at a time and the first climber usually takes the greatest risk.

The project aims to overcome these drawbacks and therefore aims to provide maximum security and flexibility for soldiers working in a cramped, urban environment. The ultimate goal of the project is to give fully-packed soldiers the ability to climb vertical walls made of standard building materials.