Research Highlight

Glowing mats to protect currency, passport

doi:10.1038/nindia.2018.80 Published online 26 June 2018

The mats appear white in daylight. When exposed to ultraviolet and near-infrared laser light, they emit red and green light, respectively. 
Researchers have synthesised glowing nanofibre-based mats, using composite nanocrystals and a polymer solution that can act as nanotags1.

Such tiny tags, when embedded in white security papers, emit a specific light. The tags can be detected with a hand-held device. The tags could be useful in detecting fake currency or imitation of vital documents such as passports — crimes that lead to huge financial losses. 

Current techniques mainly use pigment-based security ink to print security patterns, images and bar codes on security papers. However, such inks fail to stop fraudulent imitation.

In search of a better anti-counterfeiting method, scientists from the CSIR-National Physical Laboratory in New Delhi, India, led by Bipin Kumar Gupta, prepared the nanofibre-based mats using rare-earth-material-based light-emitting nanocrystals and a polymer solution.

The mats appear white in daylight. When exposed to ultraviolet and near-infrared laser light, they emitted red and green light, respectively. Such mats can be easily embedded as nanotags in confidential documents.

The light-emitting mats could help create creating next-generation high-end unique security features in currency and confidential documents, says Gupta.

References

1. Gangwar, A. K. et al. Highly luminescent dual mode polymeric nanofibers-based flexible mat for white security paper and encrypted nanotaggants applications. Chem.  Euro. J. (2018) doi: 10.1002/chem.201800715