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Posted: September 25, 2008

Nanoelectronics to the rescue of overheating computer chips

(Nanowerk News) If you've balanced a laptop computer on your lap lately, you probably noticed a burning sensation. That's because ever-increasing processing speeds are creating more and more heat, which has to go somewhere — in this case, into your lap.
Two researchers at the University of Virginia's School of Engineering and Applied Science aim to lay the scientific groundwork that will solve the problem using nanoelectronics, considered the essential science for powering the next generation of computers.
"Laptops are very hot now, so hot that they are not 'lap' tops anymore," said Avik Ghosh, an assistant professor in the Charles L. Brown Department of Electrical and Computer Engineering. “The prediction is that if we continue at our current pace of miniaturization, these devices will be as hot as the sun in 10 to 20 years."
Avik Ghosh and Mircea Stan
Avik Ghosh and Mircea Stan (Photo: Jane Haley)
To head off this problem, Ghosh and Mircea Stan, also a professor in the department, are re-examining nothing less than the Second Law of Thermodynamics. The law states that, left to itself, heat will transfer from a hotter unit to a cooler one — in this case between electrical computer components — until both have roughly the same temperature, a state called "thermal equilibrium."
The possibility of breaking the law will require Ghosh and Stan to solve a scientifically controversial — and theoretical — conundrum known as "Maxwell's Demon."
Introduced by Scottish physicist James Clerk Maxwell in 1871, the concept theorizes that the energy flow from hot to cold could be disrupted if there were a way to control the transfer of energy between two units. Maxwell's Demon would allow one component to take the heat while the other worked at a lower temperature.
This could be accomplished only if the degree of natural disorder, or entropy, were reduced. And that's the "demon" in Maxwell's Demon. "Device engineering is typically based on operating near thermal equilibrium," Ghosh said.
But, he added, nature has examples of biological cells that operate outside thermal equilibrium.
"Chlorophyll, for example, can convert photons into energy in highly efficient ways that seem to violate traditional thermodynamic expectations," he said.
A closely related concept, Brownian "ratchets," will also be explored. This concept proposes that devices could be engineered to convert non-equilibrium electrical activity into directed motion, allowing energy to be harvested from a heat source.
If computers could be made with components that operate outside thermal equilibrium, it could mean better computer performance. Basically, your laptop wouldn't burst into flames as it processes larger amounts of information at faster speeds. Also, because it would operate at extremely low power levels and would have the ability to harness, or scavenge, power dissipated by other functions, battery life would increase.
Combining Ghosh's command of physics with Stan's expertise in electrical engineering, the two hope to bridge the concept of tackling Maxwell's Demon and Brownian ratchets from theoretical physics to engineered technologies.
"These theories have been looked at from a physics perspective for years, but not from the perspective of electrical engineering," Stan said. "So that's where we are trying to break some ground."
Source: University of Virginia