"Now researchers at Carnegie Mellon University have found a new way to make such an adhesive grip and release as required, using angled microstructures."
By angling the mushroom-shaped tips of polymer fibers by 28 degrees, Professor Metin Sitt's team at Carnegie Mellon were able to support a one kilogram weight in line with the direction of the fibers, while a 300 gram weight pulling in the other direction released the grip. The 28 degree angle is similar to that found between the flattened ends and the hairs found in the pads on gecko feet.
The challenge is to increase the length of time that the adhesive will hold by making it self-clearing. For additional information, see Gecko-Inspired Directional and Controllable Adhesion.
As described in Sticky Tape Inspired by Insect Feet, part of this durability issue was solved in 2007 by a team led by Professor Stanislav Gorb at the Max Plank Institute. By structuring the hairs in a hierarchical pattern, dust would be trapped in gaps between the hairs. The flexible fibers allowed hundreds of adhesion and release cycles before adhesion was affected. Washing in soapy water restored the adhesive properties.