As more and more products are manufactured via 3D printing, the potential for inferior-quality 3D-printed counterfeit versions of those products rises accordingly. With that in mind, scientists have devised a method of ensuring that a printed item is the real thing, by building an "exploded" QR (quick response) code into it.

Developed by scientists at New York University's Tandon School of Engineering, the system instructs manufacturers' 3D printers to include hundreds of tiny elements within objects, as they're being printed. These elements are made up of inert materials, they're located in various layers within the object, and they reportedly don't compromise its structural integrity.

When the inside of that object is imaged using a micro-CT scanner or other device, all of those elements show up at once, creating a two-dimensional pattern. As long as the person operating the scanner knows the correct orientation from which to scan the object (i.e: the correct position of the object relative to the scanner), that pattern will make up a QR code which is distinct to the genuine product and its legitimate manufacturer.

If a counterfeiter were to take a product and try CT-scanning it from various angles in order to obtain its QR code, the elements within would align in various patterns, creating multiple codes – unless the counterfeiter knew the orientation in which the object was supposed to be scanned, they would have no way of knowing which code (if any) was the right one.

"By converting a relatively simple two-dimensional tag into a complex 3D feature comprising hundreds of tiny elements dispersed within the printed component, we are able to create many 'false faces,' which lets us hide the correct QR code from anyone who doesn't know where to look," says associate professor Nikhil Gupta, leader of the study.

The system has so far been successfully tested on items such as cubes, bars and spheres printed from thermoplastics, photopolymers, and metal alloys. It could also be used to create 3D exploded bar codes, or other identifiers.

A paper on the research was recently published in The Journal of the Minerals, Metals and Materials Society.

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