Whether you’re a mercenary who wishes to remain undetected as part of a covert war in Yemen or just a pimply teenager who wishes to remain undetected in high school, everybody wants to be invisible at some point. And every year, researchers at Duke University come closer to making those wishes come true. This time, through the U.S. Army Research Office and a Multidisciplinary University Research Initiative grant, assistant professor of electrical and computer engineering at Duke, Yaroslav Urzhumov, has 3D printed an early prototype for a true invisibility cloak.
In the past, attempts to create some sort of device to deflect radiation, whether it be microwaves or visible light, have relied on metamaterials made from fiber glass and copper, but Urzhumov has printed a polymer-based shield that refracts light simply due to the geometry of the shield itself. The printed object, a plastic donut-shaped disc has an array of algorithmicaly precise holes that deflect microwaves in just such a way that an object placed in the center of the ring is rendered invisible. Urzhumov explains the process in this way: “The design of the cloak eliminates the ‘shadow’ that would be cast, and suppresses the scattering from the object that would be expected. In effect, the bright, highly reflective object, like a metal cylinder, is made invisible. The microwaves are carefully guided by a thin dielectric shell and then re-radiated back into free space on the shadow side of the cloak.”
Urzhumov believes that the future for such shields is looking bright. Based off of computer simulations, he thinks that “a similar polymer-based cloaking layer as thin as one inch wrapped around a massive object several meters in diameter” is quite feasible. Additionally, printing such a shield from glass or transparent polymers using nanotechnology is a definite possibility. Finally, and most importantly to moviegoers and dreamers, Urzhumov doesn’t see how it won’t be possible to, one day soon, create shields to deflect visible light.
The US Army funded research, part of a larger subsidy given by the Department of Defense to Duke University, has obvious military applications. Dr. Jim Siedow, the vice provost for research at Duke explained that, “It’s one thing to have a stealth fighter that’s hard to see. It’s another thing to have an aircraft that literally can’t be seen — by radar or the naked eye, depending on how you align it — even though it’s there.” In fact, it’s a bit hard to imagine non-military applications for such technology. But, if it is possible to create such a shield on a standard 3D printer, as Urzhumov suggests it would be, then be on the lookout for mischievous 13 year olds in locker rooms the world over!
