The Hindu: Published on 10th March 2025:
Why in News?
Scientists from INST Mohali and BARC Mumbai have developed a new doubly secure fluorescent ink using strontium bismuth fluoride nanoparticles.
This ink offers enhanced security as it fluoresces under both ultraviolet (UV) and infrared (IR) light, unlike traditional inks that are visible under only one of these.
This breakthrough aims to strengthen anti-counterfeiting measures in banknotes, cheques, passports, and other critical documents.
Background:
Counterfeiting poses a serious threat to economies, businesses, and public safety.
Various security printing techniques such as watermarks, holograms, and optically variable inks have been employed to deter forgery.
Despite these measures, counterfeiters constantly find ways to imitate these security features, creating the need for improved solutions.
Key Innovation:
- The newly developed ink is made using Sr₂BiF₇ (strontium bismuth fluoride) nanoparticles, doped with erbium and ytterbium ions.
- The ink was combined with polyvinyl chloride (PVC) and applied using the screen printing technique.
- This ink produces different fluorescent colors under different wavelengths:
- 365-nm UV light: Emits a cool blue glow
- 395-nm UV light: Emits a magenta glow
- 980-nm near-infrared light: Emits an orange-red glow
Unique Features:
Dual-spectrum visibility: Fluoresces under both UV and IR light, making it harder for counterfeiters to replicate.
Durability: The ink remains effective under varied conditions such as brightness, temperature, and humidity.
Cost-effective production: The ink was created using a simple coprecipitation method at room temperature, making it scalable for large-scale production.
Potential Applications:
Though currently tested via screen printing, the team is working on adapting the ink for offset printing, which is widely used for printing currency notes.
Beyond banknotes, the ink can also be applied to passports, cheques, certificates, and other high-security documents.
Future Implications:
- The ink’s dual-spectrum fluorescence provides an additional layer of security in preventing forgery.
- While quantum yield (a measure of fluorescence efficiency) was not reported, experts believe that its brightness under varied conditions makes it practical for real-world use.
Conclusion:
This innovative ink has the potential to revolutionize security printing in India by offering enhanced protection against counterfeiting. Further advancements in adapting the ink for offset printing will pave the way for its integration into critical security systems.
