The rise of the machines has begun. Researchers have created artificial skin from electronic materials known as semiconductor nanowires.
A team at the University of California at Berkeley announced today it has developed a pressure-sensitive electronic material that could become the electronic skin of a robot. The artificial skin, dubbed “e-skin” by the UC Berkeley researchers, is described in a paper today in the journal Nature Materials.
This might conjure images of Arnold Schwarzenegger’s cyborg character from The Terminator. But the researchers are thinking about things that could be much more benign. A touch-sensitive artificial skin could overcome a key problem in robotics: adapting the force needed to hold and manipulate a variety of objects.
“The idea is to have a material that functions like the human skin, which means incorporating the ability to feel and touch objects,” said Ali Javey, associate professor of electrical engineering and head of the team.
“Humans generally know how to hold a fragile egg without breaking it,” added Javey. “If we ever wanted a robot that could unload the dishes, for instance, we’d want to make sure it doesn’t break the wine glasses in the process. But we’d also want the robot to be able to grip a stock pot without dropping it.”
In the long-term, another goal would be to use e-skin to restore a sense of touch to patients with prosthetic limbs. That would require a lot of advances in integrating electronic sensors with the human nervous system. Previous attempts to create artificial skin relied on organic materials because they are flexible and easier to process. But those don’t work because they’re poor semiconductors, meaning they can’t start or stop electrical signals easily.
Crystalline silicon is an excellent semiconductor, but it has historically been inflexible and easy to crack. The Berkeley group showed that miniature strips, or wires of inorganic material, can be made to be highly flexible, resulting in bendable electronics and sensors.
The engineers used a fabrication technique that works like a lint roller, only in reverse. Instead of picking up fibers, nanowires (which are fabricated at tiny dimensions) are deposited. The researchers rolled a drum and the nanowires were deposited, or printed, on a substrate. That formed the basis for creating thin, flexible sheets of electronic materials. It required less than 5 volts of power to operate the e-skin, which could detect pressure from 0 to 15 kilopascals, similar to the force used for typing on a keyboard or holding an object.
Kuniharu Takei, a post-doctoral fellow who is lead author on the study, said that the limit to the e-skin now is related to the size of the processing tools the team created.
Other UC Berkeley co-authors of the paper are Ron Fearing, Toshitake Takahashi, Johnny C. Ho, Hyunhyub Ko, Paul Leu, and Andrew G. Gillies.The National Science Foundation and the Defense Advanced Research Projects Agency helped support the research. Perhaps the silent partner here is Skynet, the fictional company in The Terminator that created the cyborg machines that took over the planet.