Water-Compatible Nanoink Enables Covert QR Printing
The new ink uses upconversion particles to allow for secure, near-infrared authentication via standard inkjet printers.
Updated on Oct. 27, 2026 in Materials Science
Researchers have developed a water-compatible nanoink using lanthanide-doped upconversion nanoparticles for near-infrared covert printing. This research-stage development enables secure document and product authentication through patterns that remain invisible to the naked eye.
Why it matters
This development advances anticounterfeiting technology by enabling covert information encoding that is easily verified via standard imaging. It provides a stable, printable medium for authentication that leverages infrared optics for increased security.
The researchers achieved a 28-fold increase in background-corrected green peak intensity across tested concentrations of 1 to 20 mg mL-1. The ink uses a 65:35 volume ratio of aqueous ethanol to glycerol to maintain printability.
The players
Canon PIXMA MG5320
A consumer-grade inkjet printer used as the deposition platform to demonstrate the viability of the nanoink.
The details
The ink utilizes LiYF4:Yb, Er@LiYF4 core-shell nanoparticles, where an outer protective layer suppresses surface defects to improve optical efficiency. These particles are coated with poly(acrylic acid) to ensure stability in water-based solvents, allowing for deposition via a standard Canon PIXMA MG5320 printer. Verification occurs when the printed QR code is illuminated by near-infrared light, which the nanoparticles convert into visible green light for smartphone-based decoding.
Timeline
October 27, 2026: Research findings were published online.
The Tech Race
This work directly addresses the challenge of transitioning upconversion nanoparticles from specialized laboratory setups to practical, high-throughput manufacturing. It positions water-compatible nanoinks as a scalable alternative to volatile, organic-solvent-based security inks.
This technology is currently in the research stage and not yet available for commercial use. Future deployment will likely target manufacturers of secure documents or high-value goods who can use existing inkjet infrastructure for covert authentication.
The takeaway
The research establishes a new benchmark for water-based, infrared-responsive inks in security applications. Future developments will likely focus on optimizing the ink's durability on non-paper substrates and expanding the available emission spectrum for multi-layered encoding.
Further reading
Learn more about the latest innovations in Materials Science.
Source note: This article includes information reported by Nature.
