Dr Goran Vladisavljevic, of Loughborough University, and a team of researchers have designed and manufactured microcapsules filled with phase change materials (PCMs) that absorb heat by turning from a solid to a liquid at elevated temperatures.
The capsules – which are around 0.2mm wide and do not require an energy source – could be used to absorb heat that would otherwise be transferred to elements in electronic devices.
They can be reused indefinitely without losing their effectiveness because once temperatures drop, they solidify and reset.
In a statement, Dr Vladisavljevic said: “The microcapsules rely on a natural phenomenon of melting and crystallisation caused when the ambient temperature is above or below the melting temperature of the phase change material,”
“Suppose that overheating occurs above 80°C. Once the temperature in a device exceeds 80°C, heat energy will be absorbed by the capsules as the phase change material transitions from solid to liquid.
“When the temperature is reduced below 80°C, the stored energy will be released slowly as the phase change material starts to solidify.
“The objective is to suppress temperature peaks in electronic parts and battery packs during load peaks, for example during short periods of maximum power consumption.”
Previous methods to create PCM-containing microcapsules involved complex, hard-to-repeat chemical processes, resulting in non-uniform microcapsules.
Overcoming this limitation, Dr Vladisavljevic and team have developed a highly reproducible, automatic process that produces uniform microcapsules using UV light and a special microfluidic device, the design of which was inspired by Lego bricks.
Manufactured at Loughborough University using an automated computer process, the device is said to produce uniform droplets of PCMs enclosed within a liquid shell. The shell hardens in several seconds when exposed to UV light, resulting in solid capsules.
Using this process, capsules can be made with different sizes, thicknesses, and types of PCM material, depending on what is needed, said Dr Vladisavljevic. They can even be made magnetic, which means they could be moved around in a device to where they are needed most.
Dr Vladisavljevic said: “There is a global appetite for smaller electronic devices, but a barrier to their development is the heat produced from electric currents flowing through the devices’ integrated circuits. This research presents a solution.
“The capsules could be used for cooling electronic devices, such as smartphones or laptops, and could even be used for cooling batteries or solar energy generators.
“The capsules have been tested for mechanical stability at Birmingham University and for durability at Karlsruhe Institute of Technology in Germany.
“We are excited to develop the capsules further and hope to test them in industry in the near future.”
The team’s findings are detailed in ACS Applied Materials and Interfaces.
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