Anti-counterfeiting holographic liquid crystal gels with color and pattern control

Lee, Kyung Min; Reshetnyak, Victor; Ambulo, Cedric P.; Marsh, Zachary M.; McConney, Michael E.; Godman, Nicholas P.

doi:10.1039/d3ma00041a

Cited by 6 publications

(4 citation statements)

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“…Consequently, we adopt a larger-scale model PaCoNet-T within the texture recognition module. The scale of PaCoBlock in the model is expanded from the original configuration [1, 1, 2, 1] to [2,3,4,3], concurrently augmenting the channel numbers in the intermediate layers of Stage 3 and Stage 4 from 48 to 80 and 96 to 160, respectively, as shown in Table 1. "Conv_K_C" and "DWConv_K_C" refer to the convolutional layer and the depthwise convolutional layer, respectively, each with a kernel size of K and output channels C i .…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…Counterfeiting is a significant global issue affecting industries such as luxury goods, cosmetics, and pharmaceuticals, leading to substantial economic losses and posing serious public health risks. − Effective and affordable anti-counterfeiting labels, along with accurate recognition algorithms, are essential to address these challenges. Various anti-counterfeiting labels have been developed, including hologram, watermarks, graphical barcodes, and security inks . However, their simplistic structures and traditional decoding methods make them vulnerable to counterfeiters, who can easily duplicate them.…”

Section: Introductionmentioning

confidence: 99%

“…1−3 Effective and affordable anti-counterfeiting labels, along with accurate recognition algorithms, are essential to address these challenges. Various anti-counterfeiting labels have been developed, including hologram, 4 watermarks, 5 graphical barcodes, 6 and security inks. 7 However, their simplistic structures and traditional decoding methods make them vulnerable to counterfeiters, who can easily duplicate them.…”

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fast and Accurate Recognition of Perovskite Fluorescent Anti-counterfeiting Labels Based on Lightweight Convolutional Neural Networks

Han,

Bao,

Shi

et al. 2024

ACS Appl. Mater. Interfaces

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Anti-counterfeiting technology has always been a key issue in the field of information security. Physical Unclonable Function (PUF) labels, which are random patterns produced by a stochastic process, emerge as an effective anti-counterfeiting strategy due to the inherent randomness of their physical patterns. In this study, we developed a high-throughput droplet array generation technique based on surface tension confinement to prepare perovskite crystal films with controllable shapes and sizes. We utilized the random distribution of perovskite nanocrystal particles to construct the PUF textures of the labels. Compared to other anti-counterfeiting labels, our labels not only possess fluorescent properties but also feature microscale dimensions (less than 5.3 × 10 −2 mm 2 ), low cost (less than 3 × 10 −4 USD), and high encoding capacity (1.7 × 10 1956 ), providing support for multilevel anti-counterfeiting protection. Additionally, we introduce an innovative PUF recognition method based on a Partial Convolutional Network (PaCoNet), effectively addressing the limitations of previous methods, in terms of recognition accuracy and speed. Experimental validation on a data set of perovskite nanocrystal films with up to 60 different macroscopic shapes and unique microscopic textures demonstrates that our method achieves a recognition accuracy of up to 99.65% and significantly reduces the recognition time per image to just 0.177 s, highlighting the potential application of these labels in the field of anti-counterfeiting.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fast and Accurate Recognition of Perovskite Fluorescent Anti-counterfeiting Labels Based on Lightweight Convolutional Neural Networks

Han,

Bao,

Shi

et al. 2024

ACS Appl. Mater. Interfaces

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“…A HPLCG is a sequence of periodically alternating layers of polymer and nematic LCs with DBR properties. Such holographic gratings are obtained from the polymerization of a photosensitive mixture of monomers and LCs in the interference field of two intersecting coherent laser beams [31][32][33][34][35][36][37][38]. It was shown that HPLCGs can be used in a hybrid structure with a metal film to excite OTSs [39].…”

Section: Introductionmentioning

confidence: 99%

Excitation and Tuning of Optical Tamm States in a Hybrid Structure with a Metal Film Adjacent to a Four-Layer Polymer–Liquid Crystal Stack

Reshetnyak,

Pinkevych,

Bunning

et al. 2024

Photonics

Self Cite

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Absorption, reflection, and transmission coefficients of the hybrid structure formed by a metal film and a holographic polymer–liquid crystal grating (HPLCG) are theoretically studied in the spectral region of the HPLCG band gap. HPLCG cells consist of four alternating layers, two layers of polymer and two layers of the same liquid crystal (LC), but with different orientations of the LC director. The appearance of reflection, transmission, and absorption peaks in the HPLCG band gap due to the excitation of optical Tamm states (OTSs) at the metal film–HPLCG interface is investigated. The dependence of the spectral manifestation of OTSs on the parameters of the hybrid structure is also studied. A comparison is made with the corresponding results for the case when HPLCG cells of a hybrid structure consist of one polymer layer and one LC layer (two-layer HPLCG).

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Wide‐Angled Pragmatic Dielectric Chiral Meta‐Platform for Spin‐ and Wavelength‐Multiplexed Holography in the Ultraviolet and Visible

Asad,

Seong,

Khaliq

et al. 2024

Adv Funct Materials

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A chiral meta‐optics platform that incorporates hologram‐multiplexing with low phase distortion and wide‐incident angle tolerance over the broad spectral range of the ultraviolet‐visible (UV–vis) regimes holds great potential for photonic‐encryption‐based applications, particularly in next‐generation 3D displays, high‐resolution biomedical imaging, holographic anti‐counterfeiting labeling, and multi‐channel optical communication. However, the design incorporating giant chirality from UV–vis wavelengths coupled with wide‐incident‐angle tolerance and cost‐effective fabrication is still challenging. Here, the study introduces a pragmatic multifunctional dielectric chiral meta‐platform designed for simultaneous spin‐ and wavelength‐multiplexing of optical information in the UV–vis spectrum. The unit cell comprises a dimer structure based on wide‐bandgap silicon nitride (SiNx), ensuring substantial dual‐spectrum chiro‐optical effects. The meticulously engineered chiral meta‐platform offers an incident angle tolerance of up to 40 degrees, coupled with significant chiro‐optical transmission. To demonstrate the concept, two distinct phase profiles are embedded in the meta‐platform, utilizing the spin and wavelength of incident light as keys to unlock the specific holographic information. The chiral meta‐platform is experimentally validated for oblique illumination angles, showcasing its adaptability across the UV–vis spectrum. The demonstrated meta‐device with dual‐spectrum visual encryption can be applied in various anti‐counterfeiting and security applications.

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Anti-counterfeiting holographic liquid crystal gels with color and pattern control

Abstract: Reflective gratings based on holographically patterned liquid crystals exhibit electrically switchable color due to changes in the periodic refractive index of the material. Previous work has shown switching behavior between...

Cited by 6 publications

References 50 publications

Fast and Accurate Recognition of Perovskite Fluorescent Anti-counterfeiting Labels Based on Lightweight Convolutional Neural Networks

Fast and Accurate Recognition of Perovskite Fluorescent Anti-counterfeiting Labels Based on Lightweight Convolutional Neural Networks

Excitation and Tuning of Optical Tamm States in a Hybrid Structure with a Metal Film Adjacent to a Four-Layer Polymer–Liquid Crystal Stack

Wide‐Angled Pragmatic Dielectric Chiral Meta‐Platform for Spin‐ and Wavelength‐Multiplexed Holography in the Ultraviolet and Visible

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