A method for producing millions of polymer microparticles that can be used as unique labels in a wide variety of industrial processes is reported in a study published online this week in Nature Materials. This method increases the number of codes that can be practically used for anti-counterfeiting applications or pharmaceutical packaging, for example.
Polymer microparticles can be barcoded for use as information carriers. However, their widespread incorporation into industrial processes is limited by the ability to easily produce a large number of particles with unique codes and to robustly decode them in harsh processing conditions.
Patrick Doyle and colleagues used flow lithography to synthesize polymer microparticles patterned with rare-earth nanocrystals that shine with specific colours when excited with a near-infrared laser. The researchers show that the microparticles can be embedded stealthily in pharmaceutical blister packaging, currency paper, credit cards, high-temperature-cast ceramics and plastic objects. The information can then be retrieved easily with a mobile phone when the embedded objects are illuminated with laser light of a specific wavelength.