The research group at Nagoya University has made a groundbreaking discovery that revolutionizes the fight against product counterfeiting. Their groundbreaking method increases the safety of cholesteric liquid crystals (CLCs) by introducing fluorescent dyes, creating fluorescent CLCs (FCLCs).
This cutting-edge technology has led to the development of exclusive labels with security features that are almost impossible to copy. These state-of-the-art labels are carefully manufactured to protect high-value goods, important documents and sensitive products. They use distinctive visual patterns that cannot be copied without special techniques and expertise.
By combining fluorescent dyes with CLCs, scientists have developed special labels that exhibit a remarkable property known as chirality, which causes the crystals to rotate in a specific direction and reflect light in a unique way. This special “light signature” provides an unprecedented level of security and makes these labels extremely difficult to reproduce.
Under normal lighting conditions, FCLCs display full color without revealing any discernible information. However, when viewed through a circular polarizer, hidden features are revealed, revealing intricate details that serve as an important security measure. In addition, these tags can contain elements that respond exclusively to ultraviolet light, providing an additional layer of verification.
“The correct information is only displayed when both decoding tools – left circularly polarized light (CPL) and ultraviolet light – are used. This two-layer security significantly improves the protection offered by existing CLC-based anti-counterfeiting labels,” explained Professor Yukikazu Takeoka from Nagoya University.
The stunning iridescent hues of FCLCs are not reproducible because the colors change depending on the concentration of the chiral dopant and light polarization. This complexity makes it difficult for counterfeiters trying to imitate the labels.
By precisely adjusting the concentration of chiral dopants, researchers have managed to reverse the direction of circular polarization. This groundbreaking ability allows FCLCs to reflect right-handed CPL and absorb left-handed CPL, thwarting counterfeiting attempts with the utmost sophistication.
The fusion of circularly polarized structural color and circularly polarized luminescence in FCLC particles represents a remarkable advance in anti-counterfeiting technology. This innovative approach holds enormous potential for protecting high-value products and protecting sensitive items from counterfeiting.
This breakthrough technology will revolutionize security measures in the near future. Imagine QR codes that are only visible under polarized light, or passwords that become visible under UV light. This dual verification system, as described by Jialei He, a key member of the research team, provides two robust layers of protection: structural color visible under polarized light and fluorescence emission visible under UV light.
“This dual verification system would provide two levels of protection: the structural color visible under polarized light and the fluorescence emission visible under UV light,” said Jialei He, a member of the research team.
These advancements represent a major step forward and make FCLCs an essential part of security protocols across various industries. Their unmatched ability to combat counterfeiting and maintain the integrity of high-quality products makes them an indispensable asset in the ongoing fight against fraud.
Journal reference:
- Jialei He, Mitsuo Hara, Ryosuke Ohnuki, Shinya Yoshioka, Tomoyuki Ikai, and Yukikazu Takeoka. Circularly polarized luminescence chirality inversion and dual anti-counterfeiting labels based on fluorescent cholesteric liquid crystal particles. ACS Applied Materials & Interfaces, 2024; DOI: 10.1021/acsami.4c08331
