Materials

Twisted material conducts and insulates heat at the same time

Twisted material conducts and ...
A visualization of the new material, which uses stacks of thin films rotated slightly to prevent heat from passing between layers, while still flowing along the film
A visualization of the new material, which uses stacks of thin films rotated slightly to prevent heat from passing between layers, while still flowing along the film
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A visualization of the new material, which uses stacks of thin films rotated slightly to prevent heat from passing between layers, while still flowing along the film
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A visualization of the new material, which uses stacks of thin films rotated slightly to prevent heat from passing between layers, while still flowing along the film

Managing heat is a major challenge in electronics and engineering, and it’s controlled using materials that either conduct or insulate heat. A new material blurs that line by blocking heat in one direction but conducting it in another.

Electronic devices heat up – it’s an annoying byproduct that influences the design of systems, lest they get fried whenever they’re running. But as electronics continue to shrink, there’s less room for cooling or venting systems, and it becomes a greater challenge to keep sensitive components away from those that run hot.

In the new study, researchers at the University of Chicago found a way to make materials that are particularly well-suited to the job. Rather than being either insulators or conductors, these new materials can kind of be both at the same time, preventing heat from moving through in one direction but allowing it to freely move in another.

“One of the biggest challenges in electronics is to take care of heat at that scale, because some components of electronics are very unstable at high temperatures,” says Shi En Kim, first author of the study. “But if we can use a material that can both conduct heat and insulate heat at the same time in different directions, we can siphon heat away from the heat source – such as the battery – while avoiding the more fragile parts of the device.”

The key is a thin film of molybdenum disulfide. Normally it’s a great conductor of heat, but the team found that by stacking sheets of the material and then rotating each one slightly, the heat was completely unable to pass between layers vertically. It could still, however, move horizontally through the sheet itself.

In practice, this technique could be used to make thermal shields that don’t just block heat but transport it away. That could not only prevent components like batteries from heating up sensitive nearby electronics, but also keep them from damaging themselves with their own trapped heat.

The technique could also improve electronics in other ways, such as by making more effective thermoelectric generators – devices that produce an electric current through a temperature differential between a hot side and a cold side.

Importantly, the researchers say that it might not just be molybdenum disulfide that enables this effect – they suspect that other materials in the same arrangement could pull it off too.

The research was published in the journal Nature.

Source: University of Chicago

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