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Current Affairs

Differential water-wetting behaviour used for anti-counterfeiting measure

Date: 05 January 2020 Tags: Nanotechnology


Researchers at the Indian Institute of Technology (IIT) Guwahati have developed a new approach to anti-counterfeiting measures. 



Researchers have developed a smart interface embedded with two different water wettabilities, extremely water repelling (superhydrophobic) and extremely water loving (superhydrophilic), which can hide information or make it visible under certain definite conditions.



  • Adding a layer of complexity, the researchers used a molecular printer to imprint a pattern of micron size that will become visible only when dipped in water or when moist air is blown.

  • The coating is not only hydrophobic but is also reactive. Taking advantage of the reactive surface of the coating, the researchers used a chemical (glucamine) to write letters on the coated surface.

  • The glucamine-treated region becomes selectively and extremely water-loving (superhydrophilic) and hence becomes visible to the naked eyes when dipped in water or when moist air is blown.

  • Since the rest of the hydrophobic region of the coated surface is still chemically reactive, they modified it using another chemical (octadecylamine) to make the surface chemically inert.

  • The pattern which is highly water-loving allows water to get in thus allowing light to pass through without much scattering. This makes the pattern visible when it is wet.

  • The rest of the region is highly water-repelling so there is trapped air that scatters light and hence remains opaque.

  • The team found the patterned coating to be physically durable even when exposed to a very high (100 degree C) and very low temperature (10 degree C).