MIT Team Develops Invisible Labels to Track and Identify Objects

A research team with MIT is bringing metadata to real-world objects. You may be familiar with the types of accompanying information embedded into digital files — the name of the song on an .mp3; the time, date, and location attached to a photo. Mustafa Doga Dogan, a fourth-year Ph.D. student in the MIT Department of Electrical Engineering, began to wonder if similar accompanying information could be attached to items encountered as you walk around, say, a store or a museum. This line of thinking solidified into a real possibility at the end of 2020 when a new smartphone model was introduced with a camera utilizing the infrared range of the electromagnetic spectrum. Now, Dogan and his colleagues have come up with a concept they refer to as InfraredTags — unobtrusive, durable tags embedded within the interior of objects fabricated on 3D printers.

Part of the design challenge was finding a suitable plastic that IR light can pass through and available as a filament spool for 3D printers. Eventually, custom plastic filaments produced by a small German company came through, showing an opacity to visible light as well as transparency to IR light on a spectrometer test. To actually produce the tags, there are a few possibilities. Either the code is carved out of tiny air gaps within a layer of the plastic, or it is imprinted in a layer of the IR-transmitting material that is backed by an opaque material, providing a contrast that makes it easier to read.

The tags themselves could look like a traditional barcode, or 2D options like QR codes and ArUco markers could be utilized to pack more information in a small tag. The MIT team has also developed a software UI that specifies what the tag should look like and where it should appear within the object. The clever invention could eventually lead to a future wherein pointing your phone camera at an object yields useful information without the need to even search for a barcode.

So far, the researchers have created several prototypes, including mugs with barcodes within the container walls, a Wi-Fi router prototype with invisible tags that reveal the network name or password, and a cheap video game controller which is just plastic with an embedded ArUco marker — turn or move the controller, and an inexpensive IR camera can be used to determine its position and orientation. Labeling and tagging systems are large parts of our everyday lives, and Dogan and his colleagues continue to imagine new possibilities for the technology in both VR and everyday life. Their paper describing methods, data, and future work is being presented at the ACM CHI Conference in New Orleans this spring and is currently available here.