Governments and financial institutions have made hard efforts to merge banknotes, checks and passports with various security features to protect them from forgery. However, every once in a while, forgers can recreate these features and pass the forged files as real files. In response, institutions are constantly developing newer and better components that are even harder to forge.
Now, scientists from India have come up with what they say ink, which they can make the criminals work harder.
Safe printing
Forgetting is a serious threat to various companies. False drugs packaged as real things can delay proper treatment or even kill. Today, branded consumer products have tamper-resistant packaging to prevent cheating from selling low-quality replicas.
Printing of items printed through safeguards is called safe printing. It has the capability that humans can detect or use simple tools themselves. Examples include optically variable ink (the color seems to change when viewed from different angles), watermarks, holograms, and secure threads. Features such as elevated shapes and texture changes are safe printing features that people can use to check for touch.
Secure printing can also include more complex features that can only be detected by the machine. Some modern passports include small RFID chips that can only be read by scanners. Other examples include invisible barcodes, digital watermarks, and holograms.
Nanoparticle solution
An important safe printing feature on Indian banknotes is the digital panel of fluorescent ink located in the lower left corner. The numbers here are visible only in UV light.
Scientists at the Institute of Nanoscience and Technology (Inst), Mohali and Bhabha Atomic Research Centre (BARC) in Mumbai are now reporting on their new ink made using nanoparticles. Nanoparticles are objects less than 100 nanometers (NM) wide. Because of their small size, their properties do not appear in larger objects: they interact with light, react differently to magnetic fields, and are chemically more reactive.
The method of discovering semiconductor nanoparticles with unusual properties has won three scientists, and the 2023 Nobel Prize in Chemistry shows the transformational effect of nanoparticles on the world.
An easy recipe
In new research, nanoparticles are made of SR2BIF7 (Strontium Fluoride Fibrogen) Doped with lantern ions. Doping is a process of intentionally adding impurities to existing crystals to impart properties that they have not previously had.
Scientists use co-precipitation technology to make particles. To do this, all metal salts in the required amount are dissolved in a suitable solvent. Once a clear solution is obtained, the required precipitant is added when stirring. They then used centrifuge to separate the deposited material.
Boddu added: “The proposed compound is a new composition and is the first time we have synthesized it by a simple reprecipitation method above room temperature, which is very easy to amplify.”
The team then got SR2BIF7 The nanocrystals contain Erbium and Ytterbium ions, both of which are lantern elements and are mixed with easy-to-use polychlorinated binary (PVC) ink. Finally, they used screen printing techniques to print some letters and numbers. Screen printing uses templates and extruders to transfer images to paper.
Tips for two lamps
When the researchers glowed 365 nm wavelength UV light on these symbols, they emitted a cool blue glow. This process is called fluorescence: when an object absorbs one wavelength and emits longer wavelengths of light. In the 395 nm light, the letters glowed in magenta. When the researchers directed near the 980 nm infrared light of the letter, they fluorescent with an orange color.
According to the team, the currently available fluorescent inks are only visible in UV or infrared light, but not both, adding that their ink stands out because it fluoresces both in the UV and near-infrared exterior positions of the spectrum. This makes their ink safer, they argue in the paper.
This low-cost ink also remains effective under brightness, temperature and humidity conditions.
Research Published In ACS Applied materials and interfaces September 2024.
Towards actual use
The paper does not report quantum yields for the system, said Bipin Kumar Gupta, a senior scientist and professor at the CSIR National Physics Laboratory in New Delhi, who was not involved in the study. Quantum yield specifies the extent to which the system converts incident light into fluorescence.
“Quantum yields are crucial for applications such as light emitting diodes and display devices. However, security applications are not very high quantum yields. … From our report, it is obvious that the material displays very good brightness at different excitation wavelengths, which is enough to achieve practical applications,” Boddu said.
Gupta obtained an Indian patent on January 30, 2022, which was patented for the same object on January 30, 2022.4) Under two wavelengths of ultraviolet light, doped with European protein and emits red and green light.
When asked about the suitability of the ink developed by Inst, Gupta said: “To print security features on currency notes, such as currency notes, usually offset printing without using screen printing.”
Offset printing uses three rollers system. The image of a cylinder from the metal plate to the rubber blanket is “offset”. The image is then transferred to the printing surface. The offset printed image is sharper and can print smaller letters.
“I agree that screen printing is not used for currency notes. However, there are many other places where screen printing can be used…we are [also] Efforts to offset the print. “There are also steps that can be used to guide practical applications, and we are working on these steps.” ”
Unnati Ashar is a free science journalist.
publishing – March 10, 2025 at 05:30 am
