A system for embedding invisible digital information in printed documents.

A team of researchers from the University of Madrid (UC3M), Massachusetts Institute of Technology (MIT), and Adobe Research have published Infrinto and Adobe Research. The technology introduces a new generation of hybrid interfaces between paper and augmented reality.

The tool was recently presented at a conference on human factors regarding computing systems (CHI 2025) held in Yokohama, Japan, and was developed with the aim of enabling sophisticated interactions with physical documents without changing their visual appearance. This study is published in the minutes of the 2025 CHI Conference on Human Factors in Computing Systems.

“Imprinto uses infrared ink that is invisible to the human eye, but can be detected by near-infrared cameras. One of the Raúl García Martín, an electronics department at UC3M, explains, for example, something that can be integrated into mobile devices by simply changing the photo sensor.

This technique opens the door to new ways of product traceability, document authentication, education or enriching professional content. Plus, everything can be done without relying on visible code such as QR codes or adding external devices.

Impprinto is part of a broader ecosystem of tools UC3M and MIT researchers are investigating based on the possibilities of infrared technology. The author also develops and processes portable cameras that can be connected to any mobile device via USB-C. This facilitates medical procedures by observing blood vessels under the skin. Furthermore, artificial intelligence algorithms allow for biorecognition based on the vascular patterns of the palm.

“The system called Veingoone aims to analyze real-time captured images, allowing not only 2D visualization, but also 3D reconstruction of vein depth using techniques such as stereoscopic and flight,” says García Martín.

Another development presented by the UC3M team is Brightmarker. This is a system that allows the use of fluorescent polymers to embed invisible code into 3D objects. This innovation allows you to print objects that contain hidden digital labels that can help industrial traceability, advanced logistics, or personalized interactions in an augmented reality environment without changing the appearance of the object.

These advancements are part of a more ambitious vision. Researchers say replacing phones with augmented reality glasses or contact lenses, which can use integrated infrared cameras to recognize and interpret the environment.

“In the near future, technologies like Impprinto, Brightmarker and Veingoone will allow users to interact with physical objects and documents in a digital, intuitive and personalized way,” concludes García Martín.