A research team has introduced a groundbreaking method for creating anti-counterfeiting labels for valuable items. Their research improves the security of current cholesteric liquid crystals (CLCs) by incorporating fluorescent dyes, resulting in fluorescent CLCs (FCLCs). This innovative technology allows the team to design highly secure labels that are nearly impossible to forge. These sophisticated labels aim to safeguard important items, critical documents, and sensitive products by producing unique visual patterns that are challenging to duplicate without the right tools and expertise.
A research team from Nagoya University has unveiled a cutting-edge technique for developing anti-counterfeiting labels meant for high-value items. Their findings, detailed in ACS Applied Materials & Interfaces, improve the security of existing cholesteric liquid crystals (CLCs) by blending them with fluorescent dyes, which leads to the creation of fluorescent CLCs (FCLCs).
Leveraging this innovative technology, the team has crafted labels with security features that are nearly impossible to counterfeit. These advanced labels are specifically designed to secure valuable goods, crucial documents, and sensitive items through the creation of unique visual patterns that cannot be easily reproduced without specialized equipment and expertise.
To make these specialized tags, scientists mix fluorescent dyes with CLCs, which causes the crystals’ helical structure to either twist left or right—this characteristic is referred to as chirality. This twisting action influences how the crystals reflect light, generating a particular “light signature.” The ability to precisely control this twisting and the consequent light patterns renders these labels nearly impossible to forge.
In regular lighting conditions, FCLCs present as solid colors with no visible details. However, when viewed through a circular polarizer, concealed features come to light, showcasing intricate designs that serve as a primary layer of security. Furthermore, these FCLCs can incorporate elements that activate solely under ultraviolet light, providing an additional verification method.
According to Professor Yukikazu Takeoka from Nagoya University: “Correct information is only revealed when both decoding methods—left circularly polarized light (CPL) and ultraviolet light—are utilized. This dual-layer security greatly enhances the safeguarding capabilities of existing CLC-based anti-counterfeiting tags.”
The distinct iridescent hues of the FCLCs change based on the concentration of chiral dopant and the light source’s polarization, adding yet another layer of difficulty for counterfeiters trying to reproduce the labels.
By meticulously adjusting the concentration of the chiral dopant, the researchers have refined the material to invert the direction of circular polarization. This modification allows the FCLCs to reflect right-handed CPL while absorbing left-handed CPL, complicating any efforts to counterfeit.
The creation of FCLC particles that exhibit both circularly polarized structural color and circularly polarized luminescence signifies a major advancement in anti-counterfeiting technology. This innovative technique has significant potential for safeguarding high-value goods and preventing forgery of sensitive products.
Looking ahead, this technology could develop to incorporate more security features, including QR codes that only become visible under polarized light or passwords that reveal themselves under ultraviolet light. As team member Jialei He noted, “This dual-verification system would deliver two layers of protection: the structural color visible under polarized light along with the fluorescent emission visible when exposed to UV light.”
With these advancements, FCLCs are poised to become a crucial component of security measures across various industries, offering unmatched protection against counterfeiting and ensuring the safety of high-value products.
