Researchers at South Korea’s Daegu Gyeongbuk Institute of Science and Technology report that a thin, moisture-absorbing film lowered the temperature of a laboratory device model by as much as 18.2°C. The study, published in Small Structures, describes a cooling layer that draws water from the air and releases it as vapor when heated.
The evaporation carries heat away from the surface without a pump or a supplied water reservoir. The film still depends on ambient moisture, however, and the headline result came from controlled tests rather than commercial electronics.
How the film cools
The hydrogel combines two cellulose-derived materials with 1-ethyl-3-methylimidazolium acetate, an organic ionic liquid that attracts water. The cellulose network gives the film structure, while the ionic liquid helps it remain flexible and stick to a surface. As a device heats up, stored moisture evaporates and absorbs heat. When the device cools, the film can take up water from the air again.
The researchers placed 40-millimeter-square layers of the film on an alumina ceramic heater used to simulate an electronic device. Tests were conducted in a chamber at 25°C and 75% relative humidity. During one-hour heating runs, the coated model reached temperatures up to 15.2°C lower than an uncovered control at 1.30 watts and up to 18.2°C lower at 2.30 watts.
