Magazine " NewScientist" 21 November 2009

NewScientist 21 November 2009

TECHNOLOGY

Built-in circuits turn contact lenses into graphics displays.

PERSONAL electronic devices tend to get ever smaller, which is great until they become so small that their screens are impossible to read. That problem could be solved by doing away with the screen, and instead projecting information into the user's eye.
That's the goal of Babak Parviz and colleagues at the University of Washington in Seattle, who hit on the idea of generating images from within a contact lens. Parviz's research involves embedding nanoscale and microscale electronic devices in materials like paper or plastic. He also happens to wear contact lenses. "It was a matter of putting the two together," he says. The polymer used in lenses cannot withstand the chemicals or temperatures typically used to manufacture microchips, but Parviz has nevertheless previously managed to embed nanoscale electronic circuits into contact lenses. Now he has managed to power those circuits by harvesting radio waves.
Parviz and his team first embedded the circuitry for a micro light-emitting diode (LED) into a contact lens by encasing it in a biocompatible material and then placing it into crevices carved into the lens. The 330 micro-LED is then fed in via a loop antenna that picks up power beamed from a nearby radio source.
The team has successfully tested the lens by fitting it to a rabbit, to demonstrate that it can be worn without damaging the wearer's eye or the circuitry- although the lens was not powered up in the test. Th components can be integrated into the lens without obscuring the wearer's view, the researchers claim.
Parviz says that future versions will be able to harvest power from a user's cellphone as it beams information to the lens. The will also have more pixels and an array of microlenses to focus the images so that they appear suspended half a metre in front of the wearer's eyes.
The device could be used to display many kinds of images, Parviz says, including subtitles when conversing with a foreign-language speaker, directions traveling in unfamiliar territory and captioned photographs. The lens could also serve as a head-updisplay for pilots or gamers, he adds.
"A contact lens that allows virtual graphics to be seamlessly overlaid on the real world could provide a compelling augmented reality experience," says Mark Billinghurst, director of the Human Interface Technology Laboratory in Christchurch, New Zealand. He sees this prototype as an important first step, though he warns that it may be years before the lens becomes commercially available.
The team will present their prototype at the Biomedical Circuits and Systems conference at Beijing, China, this month.