E-Skin Lights Up at a Touch
BERKELEY, Calif., July 22, 2013 — A user-interactive sensor network on flexible plastic could help robots become more touchy-feely, literally, enabling a new form of human-machine interaction.
The electronic skin, or e-skin, developed at the University of California, Berkeley, responds to touch by instantly lighting up. The more intense the pressure, the brighter the light it emits.
“We are not just making devices; we are building systems,” said lead researcher Ali Javey, an associate professor of electrical engineering and computer sciences at UC Berkeley and a faculty scientist at the Lawrence Berkeley National Laboratory. “With the interactive e-skin, we have demonstrated an elegant system on plastic that can be wrapped around different objects to enable a new form of human-machine interfacing.”
In this artistic illustration of an interactive e-skin developed at the University of California, Berkeley, OLEDs are turned on locally where the surface is touched. The intensity of the emitted light quantifies the magnitude of the applied pressure. Images courtesy of Ali Javey and Chuan Wang.
The latest e-skin builds on Javey’s earlier work using semiconductor nanowire transistors layered on top of thin rubber sheets. (See: Coated Nanowires Boost Photosensitivity)
To create the pliable e-skin, the engineers cured a thin layer of polymer on top of a silicon wafer. Once the plastic hardened, the material was run through fabrication tools already in use in the semiconductor industry to layer on the electronic components. After the electronics were stacked, the plastic was peeled off from the silicon base, leaving a freestanding film with a sensor network embedded in it.
“The electronic components are all vertically integrated, which is a fairly sophisticated system to put onto a relatively cheap piece of plastic,” Javey said. “What makes this technology potentially easy to commercialize is that the process meshes well with existing semiconductor machinery.”
The experimental samples measured 16 × 16 pixels; each pixel consists of a transistor, an OLED and a pressure sensor.
“Integrating sensors into a network is not new, but converting the data obtained into something interactive is the breakthrough,” said Chuan Wang, an assistant professor of electrical and computer engineering at Michigan State University who conducted the work as a postdoctoral researcher in Javey’s lab at UC Berkeley. “And unlike the stiff touch screens on iPhones, computer monitors and ATMs, the e-skin is flexible and can be easily laminated on any surface.”
A fully fabricated 16 × 16-pixel e-skin that lights up when touched.
In addition to giving robots a finer sense of touch, the engineers believe the new e-skin technology could also be used to create things like wallpapers that double as touch-screen displays and dashboard laminates that allow drivers to adjust electronic controls with the wave of a hand.
“I could also imagine an e-skin bandage applied to an arm as a health monitor that continuously checks blood pressure and pulse rates,” Wang said.
The researchers are now working to engineer e-skin sensors that respond to temperature and light as well as pressure.
The research — supported by DARPA and the Department of Energy — appeared in Nature Materials (doi: 10.1038/nmat3711).
For more information, visit: www.berkeley.edu
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