In the movie Predator, Arnold Schwarzenegger hid from an alien's night vision system by covering himself in mud. He might have found things much easier, however, if he'd had access to a newly-developed thermal camouflage material.
Developed by an international team led by the University of Manchester's Coskun Kocabas, the thin, light, flexible material is made up of three layers.
The top layer is in turn composed of multiple sub-layers of graphene (a one-atom-thick sheet of linked carbon atoms), and it serves as an electrode. The bottom layer, which is also an electrode – but of the opposite polarity – is made of heat-resistant nylon coated with gold. Between these two electrode layers is a membrane which is soaked in an ionic liquid (salt in a liquid state) that contains both positively- and negatively-charged ions.
When a small electrical current is applied to the material, the ions temporarily travel from the membrane and into the graphene. Within a matter of seconds, this drastically reduces the amount of infrared radiation (IR) emitted through the surface of the material. Most night vision cameras utilize a thermal imaging system, which detects such radiation – the amount of IR that's emitted by an object (such as a human body) is directly proportional to how warm that object is.
In lab tests, the electronically-tuneable material was successfully used to mask the thermal signature of a person's hand. It was also able to automatically adapt to the temperature of its environment, allowing it to thermally blend in with its surroundings. The researchers now hope that the technology could be used not only for hiding objects from thermal imaging systems, but possibly also in applications such as adaptive heat shields for satellites.
A paper on the project – which also involved scientists from Bilkent University and the Izmir Institute of Technology (both in Turkey) along with MIT – was published this Wednesday in the journal Nano Letters.
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