for National Geographic News
About 20 square feet (1.9 square meters) of skin covers the average adult. In that epidermis, there are nearly 4 million nerves that detect touch and more than 16,000 that detect temperature.
Robots, by comparison, are pretty numb creatures. Except for small clusters of sensors specifically embedded for certain tasks, the machines don't "feel" the objects around them.
"Most robots today interact with their environment almost entirely through visual cues. But that's often a pretty dumb way to go about it," said Gill Pratt, a specialist in robotic sensor systems at Olin College in Needham, Massachusetts.
As Pratt notes, our own tactile sense is far more sophisticated. "You can feel that you're about to crush something in your hand, but you can't see it."
Now researchers at the University of Tokyo say they have put robots in touch with the world. A team lead by Takao Someya has developed what he calls E-skin.
The meshwork of sensors laced onto a thin plastic film resembles thickly threaded fishnet stockings. When stretched over an object, such as a robotic hand, E-skin can detect pressure and temperature.
What's more, the meshwork can bend with a robot hand or other object, however it moves. Experts say this type of all-encompassing sensor system could be a big step toward developing fully functioning, humanoid robots.
Scientists overcame a major technological hurdle to develop the electronic epidermis: finding a sensor network pliant enough to fold into the jointseven the wrinklesthat might appear on a robot's face.
Silicon-based detectors, which are most commonly used in robots today, would snap under the strain of crow's feet, for example.
The Japanese researchers instead used carbon-based organic transistorssimilar to those being developed for "paper" television screens that can be rolled into a tube.
Organic transistors are basically lightweight, flexible computer circuits made from a chemical ink of organic compounds. The ink can be placed onto a backing material using methods akin to paper printing.
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