New e-skin lights up when touched, could make robots and walls more touch-friendly

The explosion in mobile devices has given us the opportunity to perfect touch interaction on screens. It’s now trivial to engineer interactive touch-sensitive surfaces into all manner of devices, but what if you need something a bit more versatile? A group of engineers at the University of California, Berkeley have created a new flexible material capable of responding to touch which can be applied to any surface. The so-called e-skin could give robots a better sense of touch, or make your living room wall into a giant touchscreen.
Led by UC Berkeley associate professor of electrical engineering Ali Javey, the team has successfully created a scrap of e-skin that responds to touch by lighting up a series of pixels. The samples of e-skin are only 16×16 pixels, but show incredible promise — this is the first time scientists have fabricated a user-interactive sensor network on flexible plastic. Each and every pixel contains a transistor, an organic light-emitting diode (OLED), and a pressure sensor.

The more pressure that is applied to the e-skin, the brighter the pixels light up. This particular application is only possible because of the OLED pixels. Regular LCDs need a backlight, which would make a flexible film impossible, but OLEDs produce light from the pixels themselves.

Researchers used a backing of silicon to act as a support for a thin layer of polymer. The wafer was run through a machine that prints integrated circuits on standard computer boards. This allowed the team to layer the necessary sensor network composed of thin-film transistors made from semiconductor-enriched carbon nanotubes onto the rigid wafer. Once the circuitry was stacked on the polymer, it was simply peeled off the silicon backing, leaving a flexible film with all the electronics built in.

The team believes that a larger, and probably more advanced version of e-skin could be used to bring touch interaction to larger areas. This plastic film could be affixed to a wall, thus bringing the sci-fi video wall to fruition at long last. E-skin is a potential game changer because the material could be applied to almost any surface, in any shape without negatively affecting its operation.
The OLED pixels are, in some way, a proof of concept — it’s a handy way to visualize the technology in action. This same kind of flexible film could be used to graft touch-sensitivity onto robots, or even prosthetic limbs. It could do away with the bulky pressure-sensors currently used in such applications and provide a more natural surface.
Pressure-sensitivity is only the beginning. With only minor changes to the production process, Javey believes e-skin can be manufactured that detects temperature and light as well. These additional capability open the door to flexible bandages that monitor pulse and blood pressure in real time. A lot of things are possible if you can get an advanced sensor laminated onto almost anything.

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