When electronics cool themselves off

Not only is graphene cheap, easy-to-make, and compact, it also manages to cool itself down when it's part of a transistor.

Graphene is a thin sheet of carbon atoms that bond to their neighbors to form a chicken-wire-type lattice precisely one atom thick. That doesn't sound too spectacular, but it has scientists in a tizzy. It has been considered for everything from DNA sequencing, to water sterilization systems, to electronics. Although each possible use requires more testing, the electronic applications give the material the most hurdles to jump before it can be declared practically useful. A little while ago, it sailed over one more bar.

As anyone who has left their electronics in a car on a sunny day knows, heat is the bane of electronic systems. As the systems gained more power, the menacing heat didn't just come from careless people and warm cars, it came from within. As electricity was pumped through transistors crammed together in an enclosed area, the devices gained the power to melt themselves - or light themselves on fire. They needed some kind of internal cooling system. That system itself used more electricity. It was a vicious cycle.

Since graphene is one atom thick, not much heat would be required to damage a graphene transistor. And since graphene is only an atom thick, it's hard to take its temperature. Scientists recently modified a microscope in order to take the temperature of a graphene transistor. They found that parts of the transistor cool themselves down as electricity moves through them.

Back in the 1800s, a physicist named Jean Charles Athanase Peltier linked together two different kinds of wire. He hooked a copper wire up to one side of a battery, hooked the other end to a length of bismuth wire, and then hooked another piece of copper wire from the end of the bismuth wire to the other end of the battery, making a full circuit. When the power flowed from copper to bismuth, the junction got very hot. When it flowed from bismuth to copper, it got very cold. Copper is more of a conductor than bismuth, and so when the electricity suddenly hit a wall of resistance, it caused the wire to heat up. When it moved from high resistance to low resistance, it caused the wire to cool.

This always happens when electricity flows between two conductors. Usually, though, the flow of electricity is powerful enough to dispel any cooling effects that the difference in resistivity might cause. Not so with graphene. The point at which the metal touched graphene cooled down dramatically, even with the heat electricity moving through it. This means that, properly made, graphene electronics might actually be able to help cool themselves down. Cheap, easy to make, compact, and self-cooling. Another piece of proof that graphene is god's chosen substance.

Image: Alex Jerez, Beckman Institute for Advanced Science and Technology

Via Nature Nanotechnology and The Physics of Refrigerators.