This Company Says It’s One Step Closer to an Invisibility Cloak

The material had been developed by Coskun Kocabas, a professor of 2D device materials at the University of Manchester and the National Graphene Center. In 2019, Vollebak approached Kocabas and proposed a collaboration to try and develop the technology further into something that could eventually resemble an invisibility cloak. “When we first started the project, we thought we might have it done in three months,” says Tidball.

It took a little longer than that to develop a first prototype. “I underestimated the material challenges,” says Kocabas, “and the challenges of working with textiles.” Three years on, Vollebak and Kocabas are finally ready to unveil their thermal camouflage jacket.

Unlike the physically impossible approach discounted in 2016, this technology is based on graphene layers. “That’s the unique material that enables us to create these tunable optical surfaces,” says Kocabas. The jacket—made up of 42 panels of graphene around 5 centimeters square that are attached to the outside of a jacket—is controlled by the electron density of the material.

“We have a multilayer graphene coating on the surface, and we intercollate ions between the graphene layers, similar to a lithium-ion battery,” says Kocabas. A voltage is passed through the layers by a computer program that charges the ions within a liquid that sits between more than 100 layers of graphene that accumulate electrons. “We basically control the electron on the graphene,” says Kocabas. That converts the graphene—an absorbing material—into a reflective material when it comes to infrared thermal radiation. Graphene’s near-unparalleled conductivity allows it to control the optics of any garment covered in it by applying voltage across it.

Video: Vollebak

Each of those 42 panels can be thought of as a pixel on a display that can be controlled individually, suggests Tidball. “A simplistic way of thinking about it is, we can turn it on and off,” he says. “A slightly more complicated way is rather than on and off, we can control how much thermal radiation each one of those patches emits.” Doing that can enable the panels to fool an infrared camera into thinking hot panels look cold, or cold panels look hot.

Of course, each panel needs to be programmed and passed to a microcontroller set within the jacket. That microcontroller then controls the voltage passed through each panel on the jacket at a different rate, depending on the pattern the wearer is trying to attain. “The critical thing is it does it with no change of temperature on the jacket itself,” says Tidball. “It’s just the thermal radiation that changes.”

Andrea Alù, Einstein professor of physics at City University of New York, and one of the researchers who in 2016 said an invisibility cloak was theoretically impossible, declined to comment on Vollebak’s claims because it lacked a supporting scientific peer-reviewed paper, making it hard to understand what the scientific progress was. Mario Pelaez-Fernandez, a postdoctoral researcher at the University of Lille specializing in graphene-related materials, says that tuning ionic liquids electrically to inform graphene patches what temperature they should display is “ingenious, and probably very expensive for the time being.” The use of the technology, she adds, is “certainly feasible.”

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