We’ve heard a lot of stories recently describing awesome bio-inspired materials, from superhydrophobic surfaces to 3D printed shark skin. Now DARPA has gone and topped the biomimetics chart by showcasing their gecko-inspired climbing paddles that allow humans to climb vertical glass walls. The technology may be a little less glamorous than a spidey suit, but who cares, this is an amazing achievement.
The devices form part of DARPA’s Z-Man program which aims to develop bio-inspired climbing equipment for use in warfare that will do away with conventional tools that have not advanced much over the years.
The demonstration involved a 218-pound (99 kilogram) man using two hand-held paddles to ascend a 25 foot (7.5 meter) glass wall, without needing a safety belay. And just to show off, they conducted another trial where the man was carrying a further 50 pounds of weight (22.5 kg).
In order to produce this impressive technology, DARPA first had to understand how geckos achieve their incredible climbing abilities. Geckos can climb on numerous different surfaces, even slippery surfaces like glass, thanks to microscopic ridges on their toes called setae. These structures are then decorated with hundreds of branching tips called spatulae which reach a maximum diameter of 200 nanometers.
These spatulae then form specific intermolecular interactions, called van der Waals forces, with the surface that allow reversible attachment to the material. Although van der Waals forces are relatively weak, the toes are covered with so many spatulae that the resulting adhesion is incredibly strong.
DARPA scientists had two main hurdles to overcome whilst attempting to mimic the gecko toe. First off, they were challenged with the issue of scaling. While a 200 gram gecko might be able to dangle from a surface by just one toe, humans are significantly heavier. Second, engineers had to develop sophisticated fabrication technologies that allowed accurate replication of the microscopic setae and spatulae.
DARPA has come a long way with this climbing technology and scientists have been trialing the innovative gear with humans for the last two years, but tests are still ongoing. DARPA also hope that the adhesives developed may have applications beyond the military in both industry and the biomedical field.