10-09 :: September 2010


nanotimes Research


9


cover image: Photo of an artificial skin made of nano- wires. The e-skin was able to accurately sense the shape of the Cal „C“ placed on top. © Ali Javey and Kuniharu Takei, UC Berkeley


left: Design layout of the artificial e-skin, using a mold in the shape of the Cal „C“ to ve- rify that the e-skin could correctly map its pressure profile. © Ali Javey and Kuniharu Takei, UC Berkeley


The UC Berkeley engineers utilized an innovative fabrication technique that works somewhat like a lint roller in reverse. Instead of picking up fibers, nano- wire “hairs” are deposited.


The researchers started by growing the germanium/ silicon nanowires on a cylindrical drum, which was then rolled onto a sticky substrate. The substrate used was a polyimide film, but the researchers said the technique can work with a variety of materials, including other plastics, paper or glass. As the drum rolled, the nanowires were deposited, or ‚printed,‘


onto the substrate in an orderly fashion, forming the basis from which thin, flexible sheets of electronic materials could be built.


In another complementary approach utilized by the researchers, the nanowires were first grown on a flat source substrate, and then transferred to the polyimi- de film by a direction-rubbing process.


For the e-skin, the engineers printed the nanowires onto an 18-by-19 pixel square matrix measuring 7 centimeters on each side. Each pixel contained a


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