Li Yuhuan, Mao Yexin, Wang Jiahui, Liu Zhiwei, Jia Pan, Wu Na, Yu Haitao, Wang Jinqiao, Song Yanlin, Zhou Jinming
Key Laboratory of Inorganic Nanomaterials of Hebei Province, College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang, 050024, P. R. China.
National Laboratory of Pattern Recognition, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
Nanoscale. 2022 Jun 23;14(24):8833-8841. doi: 10.1039/d2nr01479c.
Colloidal crystals with iridescent structural coloration have appealing applications in the fields of sensors, displays, anti-counterfeiting, . A serious issue accompanying the facile chemical self-assembly approach to colloidal crystals is the formation of uncontrolled and irregular cracks. In contrast to the previous efforts to avoid cracking, the unfavorable and random micro-cracks in colloidal crystals were utilized here as unclonable codes for tamper-proof anti-counterfeiting. The special structural and optical characteristics of the colloidal crystal patterns assembled with monodisperse poly(styrene-methyl methacrylate-acrylic acid) core-shell nanospheres enabled multi-anti-counterfeiting modes, including angle-dependent structural colors and polarization anisotropy, besides the physically unclonable functions (PUFs) of random micro-cracks. Moreover, by using the random cracks in the colloidal crystals as templates to guide fluorescent silica nanoparticle deposition, an fluorescent anti-counterfeiting mode with PUFs was introduced. To validate the PUFs of the fluorescent micro-cracks in the colloidal crystals, a novel edge-sensitive template matching approach based on a computer vision algorithm with an accuracy of ∼100% was developed, enabling ultimate security immune to forgery. The computer-vision verifiable physically unclonable colloidal crystals with multi-anti-counterfeiting modes are superior to conventional photonic crystal anti-counterfeiting materials that rely on angle-dependent or tunable structural colors, and the conventional PUF labels in the aspect of decorative functions, which will open a new avenue for advanced security materials with multi-functionality.
具有虹彩结构色的胶体晶体在传感器、显示器、防伪等领域有着诱人的应用。伴随胶体晶体简便化学自组装方法的一个严重问题是形成不受控制且不规则的裂纹。与以往避免裂纹的努力不同，这里将胶体晶体中不利且随机的微裂纹用作不可克隆的防篡改防伪编码。由单分散聚（苯乙烯 - 甲基丙烯酸甲酯 - 丙烯酸）核壳纳米球组装而成的胶体晶体图案的特殊结构和光学特性，除了随机微裂纹的物理不可克隆功能（PUF）外，还实现了多种防伪模式，包括角度依赖的结构色和偏振各向异性。此外，通过将胶体晶体中的随机裂纹用作模板来引导荧光二氧化硅纳米颗粒沉积，引入了一种具有PUF的荧光防伪模式。为了验证胶体晶体中荧光微裂纹的PUF，开发了一种基于计算机视觉算法的新型边缘敏感模板匹配方法，准确率约为100%，可实现对伪造免疫的终极安全性。具有多种防伪模式的计算机视觉可验证物理不可克隆胶体晶体在装饰功能方面优于依赖角度依赖或可调结构色的传统光子晶体防伪材料以及传统的PUF标签，这将为具有多功能的先进安全材料开辟一条新途径。
