Researchers have developed a film that can cloak thermal radiation by cutting down the infrared radiation which surfaces would normally emit.
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Springwise has followed a number of recent innovations that utilise graphene for various purposes. Such examples range from stronger, greener concrete to edible electronics. The world of thermal technology has also benefited from this material; a paint uses graphene for improved insulation and graphene-coated shoes keep feet cool.
Scientists at Bilkent University and the Izmir Institute of Technology, in Turkey, have used graphene themselves as a way to disguise the temperature of objects captured by thermal imaging. The invention makes objects appear to be the same temperature as their surroundings. Furthermore, Coskun Kocabas and his team were inspired by the cuttlefish, which uses sacs of pigment, called chromatophores, to disguise itself. The team developed a thin film consisting of a gold-coated nylon layer, a layer of film soaked in liquid salts, and several layers of graphene. When an electrical current is run through the film, ions are pulled into the graphene layers. This blocks infrared light and hides the source of heat underneath.
Additionally, Kocabas and his team found that they could also change the amount of infrared light emitted. This is done by adjusting the voltage running through the film. This means that as the background temperature changes, the film can adjust and continue to hide whatever is beneath it. The team also found a way to mimic the cuttlefish’s ability to change the patterns on their skin. They created an array made up of small squares of the film. By controlling the voltage for each square separately, they were able to create patterns visible in thermal imaging.
Kocabas, who is now a professor of materials science at the University of Manchester, suggests that one use for the film is to cover radiators on satellites, allowing them to reflect heat when facing the sun and emit excess heat when facing deep space. In what other ways might graphene be useful in improving thermal efficiency?