Scientists from Turkey, the US and the UK have developed a material that might provide the first practical thermal camouflage.
Coskun Kocabas and his team from Bilkent University in Turkey, the Massachusetts Institute of Technology, and the University of Manchester reveal their research in the journal Nano Letters.
Thermal camouflage might be the last word in tactical concealment. You’ve seen it in a hundred military thrillers and action movies – the tense chase or battle scene shown entirely in the distinct green night-time vision of infrared goggles. Sometimes the same effect is achieved with something more like the product of magnetic resonance imaging (MRI) – all cool blues and greens, with globs of dramatic yellows and reds to show the enemy just waiting to step into your crosshairs.
But where nature gives us plenty of guidance about how to hide in the visible spectrum – think of the grey, brown and green of army fatigues – there’s a dead giveaway when it comes to seeing in a different light. Warm-blooded bodies like ours give off heat that lights us up like a proverbial Christmas tree on thermal imagining.
Scientists have long tried to develop thermal camouflage – the military and law enforcement applications are obvious – but so far there have been too many practical stumbling blocks.
Any system needs to adapt to whatever background temperature it’s trying to match. It needs the ability to be built into or attached to tough materials like Kevlar. But most of all it has to be quick acting – showing up against the background for even a few seconds can be too much.
Kocabas and colleagues created a film comprising multiple ultra-thin layers of graphene and a bottom layer of gold, with non-volatile ionic liquid in between them. When a small current is applied, the ions move up into the graphene layer, cutting down the infrared radiation the surface would normally emit.
Because it’s thin, light and flexible the film can be applied to any number of surfaces, including clothing.
Tests have successfully camouflaged a hand owned by a subject wearing a covering of the material, and others have shown it to be indistinguishable from its surroundings in a variety of ambient temperatures.