A groundbreaking discovery has emerged from the research group at Nagoya University, revolutionizing the battle against counterfeit products. Their pioneering method bolsters the security of cholesteric liquid crystals (CLCs) by introducing fluorescent dyes, resulting in the creation of fluorescent CLCs (FCLCs).
This cutting-edge technology has led to the development of exclusive labels featuring nearly impossible-to-replicate security elements. These state-of-the-art labels are meticulously crafted to safeguard high-value goods, important documents, and sensitive products, using distinct visual patterns that defy replication without specialized techniques and expertise.
By combining fluorescent dyes with CLCs, scientists have developed specialized tags that exhibit a remarkable property known as chirality, causing the crystals to twist in a specific direction and reflect light in a unique way. This distinct “light signature” provides an unparalleled level of security, making these labels extremely difficult to replicate.
Under normal lighting conditions, the FCLCs display solid colors without revealing any discernible information. However, when observed through a circular polarizer, hidden features come to light, unveiling intricate details that serve as a crucial security measure. Furthermore, these tags can incorporate elements that exclusively respond to ultraviolet light, offering an additional layer of verification.
“The correct information is revealed only when both decoding tools – left circularly polarized light (CPL) and ultraviolet light – are employed. This dual-layer security significantly enhances the protection offered by existing CLC-based anti-counterfeiting tags,” explained Professor Yukikazu Takeoka from Nagoya University.
The FCLCs’ stunning iridescent hues defy replication, with colors shifting based on chiral dopant concentration and light polarization. This complexity stymies counterfeiters attempting to mimic the labels.
Through precise adjustment of chiral dopant concentration, researchers have achieved the remarkable feat of reversing circular polarization direction. This groundbreaking capability enables FCLCs to reflect right-handed CPL while absorbing left-handed CPL, thwarting counterfeit attempts with heightened sophistication.
The fusion of circularly polarized structural color and circularly polarized luminescence in FCLC particles represents a remarkable advancement in anti-counterfeiting technology. This innovative approach harbors immense potential in safeguarding high-value products and shielding sensitive items from forgery.
In the near future, this groundbreaking technology is poised to revolutionize security measures. Imagine QR codes that are only visible under polarized light, or passwords that appear under UV light. This dual-verification system, as described by Jialei He, a key member of the research team, offers two robust layers of protection: the structural color visible under polarized light and the fluorescent emission visible under UV light.
“This dual-verification system would provide two layers of protection: the structural color visible under polarized light and the fluorescent emission visible under UV light,” said Jialei He, a member of the research team.
These advancements signify a major step forward, positioning FCLCs as an essential component of security protocols across diverse industries. Their unmatched ability to combat counterfeiting and uphold the integrity of high-value products makes them an indispensable asset in the ongoing battle against fraud.
Journal reference:
- Jialei He, Mitsuo Hara, Ryosuke Ohnuki, Shinya Yoshioka, Tomoyuki Ikai, and Yukikazu Takeoka. Circularly Polarized Luminescence Chirality Inversion and Dual Anticounterfeiting Labels Based on Fluorescent Cholesteric Liquid Crystal Particles. ACS Applied Materials & Interfaces, 2024; DOI: 10.1021/acsami.4c08331