Skip to: Content
Skip to: Site Navigation
Skip to: Search

Small is big: a cellphone chip that allows monthly battery charge

When small is big: Tinier chips demand less energy and could produce a cellphone that needs a battery charge only once a month.

By Correspondent / April 12, 2011

A Massachusetts Institute of Tehcnology student tweezes a silicon wafer that, under high heat, will grow carbon nanotubes.

Ann Hermes/Staff


San Francisco

Gaming fans rushed last November to purchase a new gadget that would let them communicate with computers through body language. The device, called Kinect, "reads" players' gestures through video and infrared sensors. Players can control street-fighting or soccer-playing video game avatars just by moving their arms and shifting their stance.

Skip to next paragraph

This kind of communication blows away the joysticks used to play PacMan 30 years ago. You might say that Kinect has achieved a kind of fragmentary approximation of what brains do.

"I see that kind of technology becoming more pervasive and requiring huge amounts of computing power," says Stephen Furber, a computer chip engineer at the University of Manchester, in England.

If less energy-hungry chips are developed, cellphones could fully replace laptop computers. It could allow users to charge those cellphones once a month on a saucer-sized solar panel.

But if Professor Furber is right, the most profound result of more-efficient computers will be increasingly intelligent devices that the average person can afford.

Imagine a computer with a tiny camera mounted on your eyeglasses so that it sees what you see: As you look down the street it reads the name of every restaurant and store; it pulls up information on menus, sales, and specials, and displays it on a tiny liquid-crystal display in your eyeglasses. The computer-vision technology that Kinect uses could, in theory, be used in this kind of augmented reality – or it could allow a bipedal robot to navigate a cluttered house and do chores. But that comes at a price.

"It takes a formidable amount of computing power to process visual scenes," says Furber. Kinect's party trick costs 12 watts. But something smart enough to get around on its own – say, as smart as a squirrel – might need 10,000 watts.

Squirrel-bot's power bill makes him impractical – not to mention the hefty power cord he'd have to drag around. But people are working on more efficient computers that could nudge technology in that direction.

"Reducing the power by a factor of 100 to 1,000 is not impossible," says Eric Pop, a nanotechnologist at the University of Illinois in Urbana-Champaign. "We don't know how to do it today, but it's not impossible."

Professor Pop is working on one possible approach: Fabricate chips with new materials that conduct electricity more effectively. Better conductivity means less electricity is converted into heat – so less is needed to power the chip.

One material, called graphene, consists of a sheet of carbon atoms connected in a hexagonal, chicken-wire pattern. Graphene transistors might consume a tenth to a hundredth the power that current transistors use.

Pop is also investigating a second option for building transistors, called carbon nanotubes, in which the carbon sheet is rolled into a tube a thousandth as wide as a red blood cell. He has built simple chips containing 100 to 1,000 graphene or nanotube transistors. He can induce the nanotubes to emit different wavelengths of light – suggesting that they could also form low-power computer screens or electronic billboards.


Read Comments

View reader comments | Comment on this story