Smartwatches worn on millions of wrists today pack vastly more processing power than the computers that helped Apollo astronauts land on the moon. But the scientific drive to go tiny has come at a cost: It means heat, electricity and energy now have much less room to flow through devices.
"We will eventually reach a bottleneck to design the next generation of electronic and photonic devices," said Longji Cui, an assistant professor in the Paul M. Rady Department of Mechanical Engineering at CU Boulder. "Thermal management inside electronic devices is extremely important, but to do it more effectively, we need to understand how heat is flowing through these nanoscale devices."
Building devices at the tiny nanoscale level will require engineers to better understand how the materials inside them, like glass, behave when they are shrunk to such a small size.
In a new paper, published in the journal Nature Nanotechnology, Cui and his team discovered that at that extremely small atomic scale, heat easily flows through glass. It's counterintuitive because glass is known for being a poor thermal conductor. In fact, the heat flowed in discrete steps, each equal to 40% of the maximum amount a single channel can carry under the laws of quantum physics—the first time such "quantized" heat flow carried by atomic vibrations has been observed.
"Glass is what we put in windows to keep heat in," said Guilherme de Vilhena, a researcher at the Materials Science Institute of Madrid and a co-author of the study. "But stretch it into a thread one atom wide and it does the opposite: It lets heat through with an efficiency we had never seen in an insulator."
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