For a true cybernetic limb to work well, the wearer has to be able to feel objects when they touch them. And if robots are going to learn how to grab an egg without crushing it, for instance, they need a more sophisticated way of figuring out how much pressure they’re exerting.
Both feats may soon be achieved, thanks to a new artificial skin that senses pressure. The artificial skin, created by a Stanford University team led by chemist Zhenan Bao and physicist Gregor Schwartz, works the same way that real skin does. "We tried to mimic the function of human skin," Bao said.
One immediate practical application for the artificial skin is cardiac monitoring, Bao said. Because the sensor can be made quite thin and only uses a small amount of power, a heart monitor would be a lot less cumbersome and could even be wearable.
A touch-sensitive artificial skin would also be a good addition to prosthetics, although scientists still haven’t figured out how to connect the touch sensor to the brain. [Read also: 'Bulletproof Human Skin' Made from Spider Silk ]
The skin is essentially a large transistor. To replicate organic skin’s sense capabilities, the team used stacked layers made up of different polymers that convert pressure to an electric current that can be measured.
The artificial skin can currently sense pressures of less than 10 kilopascals, or less than a pound per square inch. That is much less pressure than a gentle touch, Bao said. Because it’s made of softer polymers, the "skin" is also flexible, unlike pressure sensors that use more conventional semiconducting materials.
Other methods have been used to make pressure sensors with that much sensitivity and resolution. For instance, a Georgia Institute of Technology team recently reported creating a similar flexible pressure sensor out of a material that is piezoelectric, meaning that pressure or twisting makes it generate a current.
Meanwhile, at the University of California, Berkeley, Ali Javey, an associate professor of computer sciences, has built devices that use a matrix of germanium and silicon nanowires rolled onto a polyimide film.
Bao said the sensor built with piezoelectric materials was a simple design, and easy to build. But she feels her method created a device that is more sensitivite to light pressures.
In addition to monitoring heartbeats and possibly improving prosthetics, there may be uses for the artificial skin that no one has even thought of yet. "Once we have such devices, we try to think what kind of application we can use it in," Bao told TechNewsDaily.
Schwartz and Bao's work appears in the May 15 issue of Nature Communications.
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