Researchers develop new technique to keep smartphones cool by sweating

Researchers have developed a technique to keep smartphones cool. A new thermal management method has been developed that aims to prevent smartphones and laptops from heating up, by releasing water vapor. As described in the journal Joule, this new method could keep electronics cooler, unlike existing strategies, by dissipating excess heat.

"The development of microelectronics puts great demands on efficient thermal management techniques because all the components are tightly packed, and chips can get really hot," said Ruzhu Wang, from Shanghai Jiao Tong University in China.

"For example, without an effective cooling system, our phones could have a system breakdown, and burn our hands if we run them for a long time, or load a big application," Wang said in a statement.

The research notes that larger devices such as computers use fans to regulate temperature. Given the bulkiness, noise and energy consumption of fans, they are not suitable for smaller devices like mobile phones, researchers said.

Although manufacturers have been using phase change materials (PCMs) like waxes and fatty acids for cooling phones by absorbing heat produced by devices when the materials melt, the total amount of energy exchanged during the solid-liquid transition is relatively low.

In comparison, the liquid-vapor transition of water can exchange 10-times the energy compared to that of PCM solid-liquid transition. Researchers also studied a group of porous materials that can absorb moisture from the air, and release water vapor when heated.

Researchers found the Metal-organic frameworks (MOFs) the most promising because they could store a large amount of water and take away more heat when heated. Previously, researchers have tried to use MOFs to extract water from the desert air.

"Our study shows electronics cooling is a good real-life application of MOFs. We used less than 0.3 grams of material in our experiment, and the cooling effect it produced was significant," Wang said.

The researchers selected a type of MOFs called MIL-101(Cr) for the experiment because of its good water-absorbing capacity, and high sensitivity to temperature changes. They coated three 16-square-centimeter aluminum sheets with MIL-101(Cr) of different thicknesses -- 198, 313, and 516 micrometers, respectively -- and heated them on a hot plate.

The team found that MIL-101Cr coating was able to delay the temperature rise of the sheets, and the effect increased with coating thickness. While an uncoated sheet reached 60 degrees Celsius after 5.2 minutes, the thinnest coating doubled the time, and didn't reach the same temperature until 11.7 minutes, the researchers said.

Researchers said that the sheet with the thickest coating reached 60 degrees Celsius after 19.35 minutes of heating.

(With inputs from PTI)