This summer, the United States Defense Advanced Research Projects Agency (DARPA) announced that its Z-Man program had, for the first time, made a gecko-adhesive-based climbing system that enabled a person to scale a wall. Although DARPA didn’t provide details on how this was accomplished, the Stanford group, which participated in the Z-Man work, has made a similar demonstration using its own adhesive system. The work is described in research published today in the Journal of the Royal Society Interface.
To make the climbing system, the researchers started with an existing adhesive based on molded microwedges made from a polymer material called PDMS. They attached tiles of this material to a flat, hexagonal, hand-sized gripper. Each gripper was backed with a spring that distributed weight across the pad, and absorbed some of the force involved in climbing. To make climbing easier, the researchers also linked the grippers to platform for a person’s feet, thereby transferring the work of climbing to the legs.
Jeffrey Karp, a bioengineer at Brigham and Women’s Hospital in Boston, notes that the test situation involved a very smooth, clean, flat surface. Karp, who cofounded a company called Gecko Biomedical to commercialize a bioinspired surgical adhesive, says the Stanford researchers will need to show that their system works in less ideal environments. In the real world, a climbing system is liable to be exposed to humidity, rain, pollen, dust, and other contaminants, he notes.
The Stanford group hopes to test the adhesive in especially extreme conditions. This month they tested it in a zero-gravity airplane with NASA and found that it still worked.
Harvard Univ. Gecko Mimicking Adhesives:Karp JM, Mahdavi A, Ferreira L, Carter D, Zumbuehl A, Borenstein J, Bettinger C, Langer R. Gecko Mimicking Adhesives. 2007.
Renewable energy-storage battery hits the market
A startup has started selling a battery that helps solar and wind power operate in remote locations.
Ask for more info: email@example.com
The batteries cost about as much as lead-acid ones, which are sometimes used now, but they last twice as long, effectively cutting the long-term costs in half (see “Demo: Storing the Sun”). Other long-lived batteries exist, but they cost far more than lead-acid batteries.
The new energy storage technology could be crucial to making renewable energy more viable, especially in remote locations. By making solar power cheaper than diesel fuel in many places, it could help bring clean power to some of the more than one billion people in the world without reliable electricity (see “A Billion People in the Dark”).