August 16, 2021

“Thermal switches” dynamically moderate heat of electronic devices

Key research finding: Modern devices that use lithium ion batteries, like smartphones and electric cars, seem pretty robust. But try to use one in extreme heat or cold, and you’ll see how susceptible they are to malfunctions and low performance due to temperature. Purdue University engineers have developed a solution: a “thermal switch” made up of compressible graphene foam, that dynamically adjusts to temperatures both inside and outside the device to maintain consistent thermal management.

As the graphene foam compresses physically (from 1.2 millimeters to 0.2 millimeters), its thermal conductance goes up by a factor of 8. As a result, the amount of heat conducted out can be fully adjustable, according to temperature conditions both inside and outside the device, which improves performance and energy efficiency.

Read more about the study. 

Purdue professors, titles:

Xiulin Ruan, professor of mechanical engineering, who focuses on nanoscale heat transfer and sustainable energy

Amy Marconnet, associate professor of mechanical engineering, who studies the thermal properties of lithium ion batteries and other devices

Journal name: Nature Communications

Funding, patent information: The Purdue Research Foundation Office of Technology Commercialization has filed a patent application based on the thermal switching technology. Contact Dhananjay Sewak for more information.

Brief summary of methods: The Purdue researchers measured the thermal conductance of the foam at Purdue’s Birck Nanotechnology Center. They sandwiched a 1.2-millimeter-thick sample of graphene foam in between a heater and heat sink, and placed the system under an infrared microscope to measure the temperature and heat flow. When fully compressing the foam to a thickness of 0.2 millimeters, the thermal conductance went up by a factor of 8. They then tested an experiment in a chamber at Purdue’s Flex Lab that can create specific environmental conditions, and achieved similar results with ambient temperatures from 0° C (32° F) to 30°C (86° F).

Media contact: Kayla Wiles, 765-494-2432,

Writer: Jared Pike

Sources: Xiulin Ruan, 765-494-5721,

Amy Marconnet, 765-494-5212,

Note to journalists: For a copy of the paper, please contact Kayla Wiles, Purdue News Service, at or 765-494-2432. Journalists visiting campus should follow visitor health guidelines.

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