Invisible 3D printed labels InfraredTags can store data in physical objects »
What if you could store the same “hidden” metadata in physical objects that you can find in digital products such as music and photos? The concept has been explored in a study by Mustafa Doga Dogan, 4th year PhD student. student at MIT, and his team. While working with colleagues from MIT CSAIL (the Computer Science and Artificial Intelligence Lab) and a Facebook researcher — Dogan came up with a concept he called InfraredTags: instead of the standard barcodes affixed to products, which can be removed or detached or otherwise becoming unreadable over time, these 3D printed labels are unobtrusive (because they are invisible) and much more durable, given that they are embedded inside objects made on standard 3D printers.
The idea, at first, was a bit abstract for Dogan. But his thinking solidified at the end of 2020 when he heard about a new smartphone model with a camera that uses part of the electromagnetic spectrum – the infrared (IR) regime – that the naked eye can’t. can not perceive. Additionally, infrared light has a unique ability to see through certain materials that are opaque to visible light. It occurred to Dogan that this feature, in particular, might be useful.
Last year, Dogan spent a few months trying to find a suitable variety of plastic that infrared light can pass through. It should come in the form of a filament spool specifically designed for 3D printers. After extensive research, he came across custom plastic filaments made by a small German company that looked promising. He then used a spectrophotometer in an MIT materials science lab to analyze a sample, where he discovered that, of course, it was opaque to visible light but transparent or translucent to infrared light – exactly the properties that he was looking for.
The next step was to experiment with techniques for making 3D-printed labels on a desktop printer. One option was to produce the code by carving tiny air gaps – proxies for 0s and 1s – into a layer of plastic. Another option, assuming an available printer can handle it, would be to use two types of plastic, one that transmits infrared light and one – on which the code is written – that is opaque. The two-material approach is preferred, where possible, as it can provide clearer contrast and therefore could be more easily read with an infrared camera.
The 3D-printed labels themselves could consist of familiar barcodes, which present information in a linear, one-dimensional format. Two-dimensional options, such as square QR codes (commonly used, for example, on return labels) and so-called ArUco (fiduciary) markers can potentially pack more information into the same area. The MIT team developed a software “user interface” that specifies exactly what the tag should look like and where it should appear in a particular object. Multiple 3D printed labels could be placed in the same object, making it easier to access information in the event that views from certain angles are obstructed.
“InfraredTags are a really smart, useful, and accessible approach to embedding information into objects,” comments Fraser Anderson, senior principal investigator at the Autodesk Technology Center in Toronto. “I can easily imagine a future where you could point a standard camera at any object and it would give you information about that object – where it was made, the materials used, or repair instructions – and you wouldn’t have not even have to look for a barcode.
Dogan and his collaborators have created several prototypes along these lines, including cups with barcodes etched inside the walls of the container, under a 1-millimeter plastic shell, readable by infrared cameras. They also made a prototype WiFi router with invisible 3D-printed labels that reveal the network name or password, depending on the perspective it’s viewed from. They have created an inexpensive, wheel-shaped video game controller that is completely passive, without any electronic components. There is just a barcode (ArUco marker) inside. A player simply spins the wheel, clockwise or counter-clockwise, and an inexpensive ($20) infrared camera can then determine its orientation in space.
In the future, if 3D-printed labels like these become mainstream, people could use their cellphones to turn lights on and off, control the volume on a speaker, or regulate the temperature on a thermostat. Dogan and his colleagues are investigating the possibility of adding infrared cameras to augmented reality headsets. He imagines walking around a supermarket one day, wearing such helmets and instantly obtaining information about the products around him: how many calories does a single portion contain and what are the recipes for preparing it?
Kaan Akşit, associate professor of computer science at University College London, sees great potential for this technology. “The labeling and tagging industry is a big part of our daily life,” says Akşit. “Everything we buy in grocery stores down to parts that need replacing in our devices (e.g. batteries, circuitry, computers, auto parts) needs to be identified and tracked properly. Doga’s work addresses these issues by providing an invisible tagging system that is mostly protected against the vagaries of time. And as futuristic notions like the metaverse become part of our reality, adds Akşit, “Doga’s tagging and tagging mechanism can help us to bring a digital copy of the items with us as we explore three-dimensional virtual environments”.