Shiv Nadar University researchers develop ‘invisible’ security ink

LUCKNOW : Shiv Nadar University on Sunday announced that its research team has created a unique ‘security ink’. This ink is not visible under normal lighting conditions, but the inked data can be seen when placed under ultraviolet (UV) light sources.

The research team comprising Debdas Ray, associate professor, and his doctoral student, Harsh Bhatia, from the department of chemistry has used organic compounds, which are environment friendly, low in toxicity and not harmful to the human body, to develop this ink.

“An intriguing result observed in our chemistry research laboratory has led to this useful, quality invention, and I would like to congratulate our research team for their work. Security ink market is expected to grow at roughly 8.3% over the next five years owing to rise in forgery and counterfeiting activities, to reach US$ 1.3 billion in 2024, up from US$ 941.8 million in 2019. This indigenous research may give us an edge,” said Rupamanjari Ghosh, V-C, Shiv Nadar University, UP.

The ink is made with the help of a commercially available polymer known as polyvinyl alcohol, dissolved in an organic solvent, either tetrahydrofuran or ethanol. After writing the characters with this ink, the paper is allowed to dry in ambient conditions for four hours, and afterwards it can be used for intended applications, Ghosh said.

This security ink phenomenon incorporates the elements of both fluorescence (emission of light immediately after light exposure) and phosphorescence (in which the absorbed radiation is re-emitted on a slightly longer timescale). When the UV light is switched on, the characters become visible in a white background due to the involvement of both fluorescence and phosphorescence and as soon as the light is switched off, the characters remain visible in a different colour only for a fraction of a second, due to phosphorescence, vice chancellor added.

The ink by virtue of its chemical composition can alter its emission abilities under specific light conditions, thereby giving it the ability to provide additional layers of security to enhance its anticounterfeit capabilities.