Running LEDs in reverse could cool computers

The miniaturization of electronics is reaching its limits in part because of heat management. Many are now aggressively trying to solve the problem. A kind of reverse-running LED is one avenue being explored.

Running LEDs in reverse could cool computers
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The quest to find more efficient methods for cooling computers is almost as high on scientists’ agendas as the desire to discover better battery chemistries.

More cooling is crucial for reducing costs. It would also allow for more powerful processing to take place in smaller spaces, where limited processing should be crunching numbers instead of making wasteful heat. It would stop heat-caused breakdowns, thereby creating longevity in components, and it would promote eco-friendly data centers — less heat means less impact on the environment.

Removing heat from microprocessors is one angle scientists have been exploring, and they think they have come up with a simple, but unusual and counter-intuitive solution. They say that running a variant of a Light Emitting Diode (LED) with its electrodes reversed forces the component to act as if it were at an unusually low temperature. Placing it next to warmer electronics, then, with a nanoscale gap introduced, causes the LED to suck out the heat.

“Once the LED is reverse biased, it began acting as a very low temperature object, absorbing photons,” says Edgar Meyhofer, professor of mechanical engineering at University of Michigan, in a press release announcing the breakthrough. “At the same time, the gap prevents heat from traveling back, resulting in a cooling effect.”

The researchers say the LED and the adjacent electrical device (in this case a calorimeter, usually used for measuring heat energy) have to be extremely close. They say they’ve been able to demonstrate cooling of six watts per meter-squared. That’s about the power of sunshine on the earth’s surface, they explain.

Internet of things (IoT) devices and smartphones could be among those electronics that would ultimately benefit from the LED modification. Both kinds of devices require increasing computing power to be squashed into smaller spaces.

“Removing the heat from the microprocessor is beginning to limit how much power can be squeezed into a given space,” the University of Michigan announcement says.

Materials Science and cooling computers

I’ve written before about new forms of computer cooling. Exotic materials, derived from Materials Science, are among ideas being explored. Sodium bismuthide (Na3Bi) could be used in transistor design, the U.S. Department of Energy’s Lawrence Berkeley National Laboratory says. The new substance carries a charge and is importantly tunable; however, it doesn’t need to be chilled as superconductors currently do.

In fact, that’s a problem with superconductors. They unfortunately need more cooling than most electronics — electrical resistance with the technology is expelled through extreme cooling.

Separately, researchers in Germany at the University of Konstanz say they soon will have superconductor-driven computers without waste heat. They plan to use electron spin — a new physical dimension in electrons that could create efficiency gains. The method “significantly reduces the energy consumption of computing centers,” the university said in a press release last year.

Another way to reduce heat could be to replace traditional heatsinks with spirals and mazes embedded on microprocessors. Miniscule channels printed on the chip itself could provide paths for coolant to travel, again separately, scientists from Binghamton University say.

“The miniaturization of the semiconductor technology is approaching its physical limits,” the University of Konstanz says. Heat management is very much on scientists’ agenda now. It’s “one of the big challenges in miniaturization."

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