Prototype jacket proves wearable thermal camouflage

The prototype jacket - made with graphene and incorporating a microcomputer that controls the amount of thermal radiation emitted by it – is the result of work carried out by London-headquartered clothing brand Vollebak, the National Graphene Institute (NGI) and the Graphene Engineering Innovation Centre (GEIC) at Manchester University. 

According to Vollebak, the Thermal Camouflage Jacket incorporates 42 patches of graphene which can be individually controlled via microcomputer to emit different levels of thermal radiation, without any change to their temperature. Programming the patches to have the same level of thermal radiation as their surroundings makes them appear ‘invisible’ to infrared cameras.

“The prototype Thermal Camouflage Jacket proves the viability of wearable thermal camouflage for the first time and I can now confidently say that the concept of an invisibility cloak is no longer science fiction,” said Coskun Kocabas, Professor of 2D Device Materials at Manchester University and NGI. “The reason we’ve used graphene in the jacket is because it’s a highly tuneable material, which means that applying energy to it changes how it appears on both the infrared spectrum and the visible spectrum.”

Kocabas continued: “While the Thermal Camouflage Jacket only operates on the infrared spectrum today, it should ultimately be possible to build a version that also operates on the visible spectrum, and this will be the invisibility cloak that the world’s been waiting for.”

Each graphene patch in the prototype jacket contains hundreds of atom-thick layers of graphene which is grown at the GEIC in a high-temperature furnace that reaches around 1,000^oC. Gold and copper wires printed on a polyimide film run from the graphene patches to a microcontroller on the jacket, which is attached to a computer. Code can be uploaded to this microcontroller, which then delivers voltage to each patch of graphene. The electrical current forces ions between the layers of graphene, which changes its optical properties. The more ions pushed between the graphene layers, the colder it looks, and the less thermal radiation it emits. 

Origins
The collaboration began in 2019 after Vollebak released the world’s first jacket made from graphene. Vollebak co-founders Nick and Steve Tidball were invited to meet with scientists at the NGI and share their experiences of creating clothes from graphene. Here, they met Professor Kocabas who was investigating new applications for a graphene-based patch he had developed that could be applied to an object and then charged with an electrical current to make a hot object appear cool and vice versa. 

“We were already convinced that graphene’s ability to conduct heat and electricity made it an incredibly exciting material to work with – one that could be the basis for clothing we’ll be wearing in 100- or 1,000-years time,” said Steve Tidball. “Professor Kocabas showed us how he’d blended his graphene-based thermal camouflage patch with a small piece of material, and it felt like we were looking into the future – and we wanted to help take it as far as possible towards wearable thermal camouflage.”

Vollebak commissioned the National Graphene Institute to scale up the fledgling technology into a piece of clothing, and over the next three years the Vollebak team worked with Professor Kocabas and his colleagues to develop the prototype Thermal Camouflage Jacket.