Artificial Skin

Is it important to know if you’re holding an egg versus a stockpot? How about feeling the weight of a fly on your skin?

UC Berkeley and Stanford researchers think so. In two separate papers published this week in Nature Materials, they each reveal their ideas for artificial skin.

UC Berkeley engineers created their “e-skin” out of nanowires, utilizing an innovative fabrication technique that works somewhat like a lint roller in reverse. Instead of picking up fibers, nanowire “hairs” are deposited. Pressure-sensitive rubber integrated with nanowire transitors provides sensing functionality.

Stanford scientists created their artificial skin by sandwiching a precisely molded, highly elastic rubber layer between two parallel electrodes, creating an electronic sensor that can detect the slightest touch. The film of rubber is molded into a grid of tiny pyramids—allowing the rubber to bounce back quickly. The speed of compression and rebound of the rubber is critical for the sensor to be able to detect—and distinguish between—separate touches in quick succession.

(You can see a video showing this process and an image of UC Berkeley’s e-skin on Popular Science’s website.)

Stanford’s skin is able to feel the light touch of a butterfly or other insect—or maybe not so light (Bad Astronomy has a recent blog post about the haunting touch of a preying mantis).

UC Berkeley’s researchers hope the e-skin will be able to monitor the amount of force needed to hold and manipulate a wide range of objects.

“Humans generally know how to hold a fragile egg without breaking it,” said Ali Javey, part of the UC Berkeley team. “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.”

But this isn’t just about a robot unloading your dishes. Researchers on both sides of the Bay hope that, once developed, these artificial skins will help people with prosthetic limbs.

Image credit: Ali Javey and Kuniharu Takei