Revolutionary Dual-Fluorescent Security Ink Developed by Indian Scientists

Revolutionary Dual-Fluorescent Security Ink Developed by Indian Scientists

Sub: Sci

Sec: Msc 

Why in News

• Scientists from the Institute of Nano Science and Technology (INST), Mohali, and the Bhabha Atomic Research Centre (BARC), Mumbai, have developed a novel security ink using strontium bismuth fluoride (Sr2BiF7) nanoparticles. This new ink fluoresces under both, enhancing security against counterfeiting.

Security Printing:

• Security printing is a critical measure to prevent counterfeiting in banknotes, passports, cheques, and branded consumer goods.

Security Features in Printing:

• Optically Variable Ink: Changes colour when viewed from different angles.
• Watermarks and Holograms: Provide authentication layers.
• Security Threads: Embedded in currency notes to enhance protection.
• Raised Textures and Shapes: Allow tactile verification.
• Digital Watermarks and Barcodes: Require electronic scanning for verification.
• RFID Chips in Passports: Enable machine-readable authentication.

Nanoparticle-Based Fluorescent Ink:

• A major security feature in Indian banknotes is the number panel printed with fluorescent ink, visible only under UV light.
• The newly developed ink by INST and BARC scientists offers an advanced level of security due to its dual fluorescence.
• Properties of Nanoparticles:
• Size Below 100 nm: Allows unique interactions with light and magnetic fields.
• High Reactivity: Enhances chemical stability and durability.
• Improved Optical Properties: Alters fluorescence behaviour under different wavelengths.
• Composition: The ink is formulated using strontium bismuth fluoride (Sr2BiF7) nanoparticles doped with lanthanide ions (erbium and ytterbium).
• The coprecipitation technique was employed for synthesis, wherein metal salts were dissolved in a solvent and precipitated using a chemical agent under stirring.
• The synthesized nanoparticles were blended with polyvinyl chloride (PVC) ink and used in screen printing to produce security markings.
• Under 395-nm UV light, it fluoresced magenta, while 980-nm near-IR light triggered an orange-red emission.
• This dual fluorescence makes it highly secure against forgery attempts.
• INST-BARC Ink: Uses Sr2BiF7 doped with lanthanides, exhibiting dual fluorescence.
• CSIR-NPL Ink: Uses gadolinium vanadate (GdVO4) doped with europium, emitting red and green fluorescence.
• Researchers noted that extremely high quantum yield is not essential for security applications, as the ink exhibits sufficient brightness under different lighting conditions.

About Quantum Yield:

• Quantum yield quantifies the efficiency of a photophysical or photochemical process.
• It is defined as the ratio of the number of specific events (e.g., photon emission, chemical reactions) to the number of photons absorbed by the system.

Applications:

• Fluorescence Spectroscopy: Measures the efficiency of the fluorescence process. Crucial in designing fluorescent probes and dyes for biological imaging and analytical applications.
• Photochemical Reactions: Determines the number of molecules undergoing a photochemical transformation per absorbed photon.
• Photosynthesis Research: Quantum yield is used to model the efficiency of photosynthetic organisms in converting light energy into chemical energy.
• Material Science and Nanotechnology: Quantum yield is essential in evaluating the performance of materials like quantum dots and nanoparticles, especially in applications involving light emission, such as display technologies and photovoltaic cells.

About Counterfeiting:

• Counterfeiting refers to the act of imitating, reproducing, or fabricating goods, currency, documents, or trademarks without authorization, with the intent to deceive consumers or gain illicit financial benefits.
• Currency Counterfeiting: Producing fake banknotes, coins, or digital currencies to circulate them as genuine money.
• Product Counterfeiting: Manufacturing fake versions of branded goods, including luxury items, electronics, pharmaceuticals, and consumer products.
• Document Counterfeiting: Forging passports, identity cards, educational certificates, and legal documents.
• Intellectual Property (IP) Counterfeiting: Copying patented designs, trademarks, or copyrighted content without authorization.