Vollebak believes its thermal camouflage jacket with graphene proves that invisibility could happen in the future.
The dream of tech that grants us invisibility has long been an obsession. But it has, for now, remained in the realm of science fiction. As recently as 2016, researchers had concluded that the fundamental laws of physics meant a true invisibility cloak wasn’t possible.
That may no longer be the case. A 2019 patent, filed by a Canadian company called Hyperstealth Technology, suggested that it’s possible to bend light around an object using a “quantum stealth” cloak to make it disappear—albeit not perfectly. And militaries around the world continue to try to make the technology work. In 2020, the Israeli Ministry of Defense and tech company Polaris Solutions announced a 500-gram thermal visual concealment sheet that uses polymers to conceal anyone or anything underneath it.
However, a new method, developed by an apparel company best known for a metal jacket made from bulletproof material, a copper-infused garment designed to kill viruses, and an algae-based T-shirt that composts in 12 weeks—in collaboration with a UK academic—suggests that what was once thought of as a closed-off direction in technology could once more be open. That company, UK-based Vollebak, has developed a prototype of a thermal camouflage jacket that it says signals a critical first step towards an invisibility cloak.
“We’ve been thinking about invisibility ever since we started the company,” says Steve Tidball, cofounder of Vollebak. “We came out with some bold claims when we first started that we’re going to make clothes for the future. And many, many customers have written to us and said, ‘How about an invisibility cloak?’” But it wasn’t until Tidball saw a photograph of a graphene-based material that can fool an infrared camera into thinking there wasn’t anything there that he first felt it could become reality. “I thought that’s got to be a first step towards invisibility,” says Tidball.
The material had been developed by Coskun Kocabas, a professor of 2D device materials at the University of Manchester and the National Graphene Center. 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.
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.”
Despite the bold claims linking the jacket to invisibility cloaks, Tidball and Vollebak are up-front about the fact that this is little more than a proof of concept. Unlike some other innovations the clothing company has developed, the thermal camouflage jacket is not yet for sale—and may not be for some considerable time. Wearers of the jacket are, for the time being, umbilically connected to a computer with wires. “Even though it’s got wires sticking out of it, and even though it’s attached to a computer, it’s still really exciting for me,” says Tidball. “Because the first iterations of clothing and technology merging are going to look like the Delorean from Back to the Future. It’s going to have wires sticking out of it, and it’s going to look like it’s come out of a lab.”
Naturally, having thought that developing a working thermal invisibility cloak would take three months, only for it to take 12 times that, Tidball is more realistic about estimations of when the clunky-looking prototype jacket can become something fully wearable for all. “Ultimately, you’re still a good five or 10 years away from actual invisibility,” he says, and this is before even figuring out how to miniaturize it in a way that would enable it to be sold on the high street. “This is just a step on the journey, to trick infrared cameras,” he says.
By Chris Stokel-Walker.
Full article available here.
