Invisibility

Duke researcher Yaroslav Urzhumov and his team created a disc with a non-industrial 3D printer to deflect microwave beams. (Image courtesy of Duke Universiety and the Fayettvill Observer)

Additive manufacturing, more commonly known as 3D printing, is the process of producing solid objects from digital blueprints. 3D printing has proliferated since the start of the twenty-first century, and its technology is currently used in jewelry and footwear manufacturing, industrial design, engineering, aerospace, and the medical and dental industries (1).

At Duke University, researchers say they have developed a way to produce an invisibility cloak from 3D printers. The concept of an invisibility cloak was first introduced seven years ago in a laboratory, but the engineers at Duke have made the technology accessible from off-the-shelf 3D printers (2).

The term ‘invisibility cloak’ is slightly misleading in the context of the current progress of the research. The cloaking technology developed at Duke’s Pratt School of Engineering is more akin to a Frisbee made of Swiss cheese than any wearable invisibility device. Also, at the moment it only disguises an object from microwaves, and is ineffective against light in the visible spectrum (3).

The Frisbee-esque ‘cloak’ has a large hole in the middle, and algorithmically placed holes scattered across the rest of the device. These holes disguise the object placed in the center hole from microwave beams aimed through the side of the disk, making it seem that the object isn’t there (3). More technically, the substance of the cloak is a manmade material composite that refracts microwaves around the object (4). The microwaves are prevented from scattering off the object in the center of the cloak; rather, they are guided through the cloak and reradiated into space on the other side of the device (2).

Current versions of the cloak are constructed from fiberglass and copper, but the team at Duke University, led by Yaroslav Urzhumov, assistant research professor in electrical and computer engineering, is experimenting with a polymer-based cloak. The polymer cloak would eliminate the expected shadow cast by the object (4).

Another novelty of Urzhumov’s work is that this cloak can be produced in just a few hours from non-industry grade 3D printing. Urzhumov said, “I would argue that essentially anyone who can spend a couple thousand dollars on a non-industry grade 3D printer can literally make a plastic cloak overnight” (2).

The cloak is relatively thin, measuring approximately one microwave wavelength thick, and its developers believe the technology could be applied to higher frequency radiation – namely, visible light (4). Urzhumov also stated that he thinks the cloaks themselves could become more invisible one day by forging them from transparent polymers and glass. Further, Urzhumov and colleagues at Duke and University of California at San Diego believe 3D printing will be able to fabricate larger cloaks (2).

Though the invention is still somewhat early in its development, Urzhumov and his team believe it has great potential as a cloaking device for wide frequencies, including the visible spectrum (3). Planes, for example, could be wrapped in a cloak to prevent visible or infrared detection.

References

1. 3D Printing (10 May, 2013). Available at http://mashable.com/category/3d-printing/.

2. Damon Poeter, Researchers use 3D Printer to Craft ‘Invisibility Cloak’ (10 May, 2013). Available at http://www.pcmag.com/article2/0,2817,2418728,00.asp (8 May, 2013).

3. Michelle Starr, 3D-print your own invisibility cloak, kind of. Engineers at Duke University have used 3D printing to create an object that can shield against detection from microwave beams (10 May, 2013). Available at http://news.cnet.com/8301-17938_105-57583250-1/3d-print-your-own-invisibility-cloak-kind-of/ (7 May, 2013).

4. Liat Clark, Study: Engineers 3D-print working ‘invisibility cloak’ (10 May, 2013). Available at http://www.wired.co.uk/news/archive/2013-05/7/3d-printed-invisibility-cloak (7 May, 2013).