31st March 2025 (31 Topics)

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Doubly secure ink to thwart counterfeiting

Context

Scientists from the Institute of Nano Science and Technology in Mohali and the Bhabha Atomic Research Centre in Mumbai have developed a new security ink using nanoparticles of strontium bismuth fluoride doped with lanthanide ions to prevent counterfeiting.

The new Nanoparticle-Based Ink

Scientists used a process called the coprecipitation technique.
Metal salts were dissolved in a solvent.
A precipitation agent was added while stirring.
The solution was centrifuged to extract the nanoparticles.
The material was blended with polyvinyl chloride ink.
Screen printing was used to apply the ink to paper.
The Two-Light Trick: Unlike conventional fluorescent inks, which glow under either ultraviolet or infrared light, this ink fluoresces under both.
Under 365 nanometer ultraviolet light, it emits a blue glow
Under 395 nanometer ultraviolet light, it emits a magenta glow
Under 980 nanometer infrared light, it emits an orange-red glow
This multi-wavelength fluorescence makes it more difficult to counterfeit.

Understanding Security Printing

Security printing includes features that help authenticate documents and prevent counterfeiting. These features can be
Visible to the Human Eye
- Optically variable ink, which changes color when viewed at different angles
- Watermarks, which are embedded patterns visible when held against the light
- Holograms, which are three-dimensional images that are difficult to duplicate
- Security threads, which are embedded strips visible under certain conditions
- Textured features, which are raised prints detectable by touch
Detectable by Machines
- Ultraviolet fluorescent ink, which becomes visible under ultraviolet light
- Invisible barcodes and digital watermarks, which are scannable security markers
- RFID chips in passports, which allow machine-readable verification

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