A research team led by Professor Kim Sang-ouk of the Department of Materials Science and Engineering at the Korea Advanced Institute of Science and Technology (KAIST) has developed a security technology that verifies authenticity using nothing more than ordinary light, working jointly with a team led by Professor Kwon Seok-joon of Sungkyunkwan University.
KAIST said on the 26th that the findings were recently published online in the international journal Nature Communications.
The two teams let round particles measuring several hundred nanometers, or billionths of a meter, assemble on their own on the surface of water. The positions and orientations the particles settle into differ every time, so a distinct pattern forms naturally. The process resembles the way small grains land in a different arrangement each time they are scattered on a floor. The teams used these randomly formed particle arrangements as a unique "nano-fingerprint."
When ordinary light such as a smartphone flashlight is shone on the surface, a unique color and reflection pattern appears depending on how the nanoparticles are arranged. When a laser pointer is used, the light meets the fine particle structure and scatters in multiple directions, producing another distinct light pattern. The researchers registered both light patterns for each product in advance and verified authenticity by comparing them with the patterns observed on the actual item.
Counterfeiting would require reproducing not only the nanoparticle structure itself but also the color and reflection pattern seen under a flashlight and the light pattern seen under a laser. The teams also succeeded in transferring the nanostructure onto a range of surfaces, including flexible plastic, metal, transparent film and hydrogel, a soft gel-like material capable of holding large amounts of water.
"The key to this study is that it creates a random structure that is difficult to replicate while still allowing authenticity to be checked easily with simple tools such as a flashlight or a laser pointer," Kim said. "It will develop into a next-generation security technology that can be used readily in everyday life, including for authenticating electronic devices and for anti-counterfeit labels."
