Anti-counterfeiting Features Research Articles

Novel multi-mode anti-counterfeiting encryption material of CaAl12O19:Eu, Er with multi-color down-conversion luminescence, up-conversion luminescence, dynamic luminescence, and photochromism

Multi-mode dynamic anti-counterfeiting materials can provide complex anti-counterfeiting performance and ensure the anti-counterfeiting strategy becomes more secure. Herein, a new type of multi-mode anti-counterfeiting encryption material of CaAl12O19:Eu, Er with different Er doping concentration was developed by sol–gel method. Interestingly, the CaAl12O19:Eu, Er phosphor and its composite have multi-mode anti-counterfeiting characteristics of multi-color down-conversion luminescence, up-conversion luminescence, dynamic luminescence, and photochromism. Effect of different Er doping concentration on the down-conversion luminescence, up-conversion luminescence, dynamic luminescence, and photochromism of CaAl12O19:Eu, Er was systematically investigated, and the relevant mechanisms were discussed. These anti-counterfeiting features can be simultaneously applied in both bright and dark fields, which can achieve high-level anti-counterfeiting in both spatial and temporal dimensions. The CaAl12O19:Eu, Er phosphors cannot be easily replaced by other materials with the same anti-counterfeiting properties. They display good application foreground in the field of anti-counterfeiting encryption.

Anticounterfeiting Feature of a Writable and Self-Erasable Ni(II)-Metallogel Pad via Fluorescent "Turn-On" Detection of Cyanide.

A Schiff base 5-(2-hydroxy-3-methoxybenzylidieneamino)-1-H-imidazole-4-carboxamide (HL) comprising multibinding sites has been synthesized with the aim of fabricating a supramolecular gel. The gelator HL was characterized by FT-IR, 1H & 13C NMR, and ESI-MS techniques and also formed a [Ni(L)2] complex. The gelation property of HL was investigated with various metal ions, wherein Ni(II) selectively forms a mechanically and thermally stable supramolecular metallogel (MG) in the presence of a triethylamine base in DMF-MeOH media. Characterization of MG was accomplished with different spectro-analytical techniques such as FT-IR, ESI-MS, powder-XRD, SEM, rheological investigations, UV/vis, and fluorescence. The gelator HL displays moderate emission upon addition of Ni2+ and gives "turn-off" fluorescence output by forming the complex [Ni(L)2] (MG) due to the chelation-enhanced quenching of fluorescence (CHEQ). Job plot and ESI-MS data suggested a 2:1 stoichiometry between HL and Ni(II) in MG. Further, MG exhibited highly selective and ultrasensitive "turn-on" fluorescence signaling with CN- in the background presence of several cations and anions. The limit of detection (LoD) of MG was determined to be 6.9 × 10-9 M for CN- using the fluorescence technique. Notably, MG behaves as a fluorescent writable pad material explicitly with CN- under 365 nm UV light but not under ordinary light and the fluorescent text is self-erased after 15 min. Hence, MG can be used as a metallogel pad in the presence of CN- to communicate secret messages. Overall, the present work explores the fabrication of a thermo- and mechanostable Ni(II)-metallogel (MG), which selectively and ultrasensitively detects CN- both in the solution phase and in the gel form, wherein MG behaves as a writable and self-erasable pad with anticounterfeiting features for practical applications.

Resilient photoswitchable metal–organic frameworks for sunlight-induced on-demand photochromism in the solid state

Organic photoswitchable molecules have struggled in solid-state form to fulfill their remarkable potential, in terms of photoswitching performance and long-term stability when compared to their inorganic counterparts. We report the concept of non-electron deficient host’s surface with optimal porosity and hydrophobicity, as a priori strategy to design photoefficient organic solid-state photochromic materials with outstanding mechanical robustness. It is realized by the nanoconfinement of photochromes in a host matrix possessing optimal porosity and hydrophobicity. The resulting photochromic nanocomposites can be prepared in multigram scale employing a one-pot reaction under ambient conditions. When exposed to a light stimulus including natural sunlight, the photoswitchable nanocomposite powder changes color promptly and reversibly, in a matter of seconds (5 s and 30 s under UV irradiation and sunlight, respectively) along with excellent photo-fatigue resistance, which are on a par with inorganic photochromes. Exemplars of commercially viable prototypes that are optically clear, comprising smart windows, complex photochromic sculptures, and self-erasing rewritable devices, were engineered by direct blending with resilient polymers. Notably, the use of high-stiffness polymers (Young’s modulus > 2 GPa) is no longer considered an insurmountable challenge. Finally, photochromic films with anticounterfeiting features could be manufactured through precision printing of nanocrystals by drop-on-demand inkjet printing technology.

COMPONENT COMPOSITION OF INKS, PAINTS AND DYES AS AN IMPORTANT COMPONENT OF DOCUMENT PROTECTION AGAINST COUNTERFEITING

This article analyzes the component composition of inks, paints and dyes, and also gives a general description of one or another type of ink or dye and a classification of some of them. The historical aspect of the manufacture of inks and their components is highlighted. Writing ink was first made in ancient Egypt and China around 2500 BC. The features of paints depending on the type of printing (high, gravure, flat offset, screen) are studied and examples of their application are given. Flat offset inks used in newspapers are usually simple in composition. As for letterpress, although this type is gradually being replaced by other printing processes, it is still used in the production of money, most paper-based forms in printing serial numbers, etc. Gravure inks are similar to flexographic inks, except that ketones and aromatic hydrocarbons can be used as solvents, allowing much greater freedom in the choice of binders. This type of ink for inkjet printing, such as solvent ink, is considered in detail. Solvent ink is a complex physical and chemical system for inkjet printing, consisting of pigment, polymer, film former, solvent and special additives. The structural composition of solvents is characterized, which, getting on paper, undergoes a number of changes over a fixed period of time, as a result of which the dye dries on paper. Ethanol, benzyl alcohol and many other solvents can also be used as carriers. The choice of solvent or solvents often depends on the properties of the writing instrument. The so-called «invisible» ink (UV ink, thermosetting ink, etc.) was studied separately as a kind of protective element. This type of ink is mainly used in steganography, anti-counterfeiting and currency security features, packaging authenticity indicators, brand protection, and secret messages. Conclusions are drawn, emphasizing that understanding the principle of operation of one or another element of protection allows forensic experts of forensic technical examination of documents to effectively identify forgery.

A mango biological fingerprint anti-counterfeiting method based on Fuzzy C-means clustering

The anti-counterfeiting of agricultural products plays an important role in protecting the rights and interests of consumers and maintaining the healthy development of the food market. Traditional anti-counterfeiting technology mainly relies on anti-counterfeiting features of packaging or labeling, which has the risk of being copied and reused. Biological fingerprint anti-counterfeiting is a method of anti-counterfeiting that takes the biological fingerprint of agricultural products as the anti-counterfeiting feature. This paper aims to take the distribution of lenticels on the surface of mango as a biological fingerprint, and propose a mango biological fingerprint anti-counterfeiting method. As the mango ripens, the peel color of mango will change significantly, which will affect the accuracy of anti-counterfeiting identification. In this paper, the images of ripe mangoes are classified by Fuzzy C-means clustering, and appropriate image enhancement technology is used to highlight the features. The results show that the mango biological fingerprint anti-counterfeiting method based on Fuzzy C-means clustering has good accuracy and robustness, and effectively reduces the impact of peel color change on anti-counterfeiting identification during mango ripening. These results support that it is feasible to use the lenticels distribution of mango as a biological fingerprint. In this paper, a computer vision anti-counterfeiting method based on lenticels distribution is proposed.

Multi-dimensional dynamic fluorescence readout from laser engineered In2O3 nanowire micropatterns

A laser-irradiated array of In2O3 nanowires presents yellow and blue fluorescence states that can be dynamically altered under UV light for anti-counterfeiting features based upon microscale patterning, color evolution and time-domain encoding.

Tri-channel tubular lanthanide nanocomposites for multimodal anti-counterfeiting

Integrating multiple signals with different excitation wavelength dependence and temperature response properties into a single nanomaterial to construct multimodal anti-counterfeiting materials is still challenging. In this research, an exciting lanthanide hybrid tri-channel tubular anti-counterfeiting nanomaterial was fabricated by fixing NaYF4:Yb3+/Tm3+ up-conversion nanoparticles and Cit-Eu-TC complex on the surface of YHF:Ce/11.4%Tb nanotubes, which can be further used to make anti-counterfeiting fluorescent ink and hydrogel. The hidden three-mode anti-counterfeiting patterns showed bright green, red, and blue-violet fluorescence under 254 nm, 365, and 980 nm excitation, respectively. More importantly, under the co-irradiation of 254 and 365 nm light, the patterns prepared by the anti-counterfeiting ink showed mesmerizing dynamic anti-counterfeiting performance under the stimulation of developer and temperature. With the developer's dosage increase or temperature change, the color of anti-counterfeiting patterns changed obviously. The combination of this dynamic stimulus-responsive anti-counterfeiting feature and the above three-channel static anti-counterfeiting feature might bring about multi-mode static-dynamic anti-counterfeiting performance, significantly improving the difficulty of forgery and was expected to be widely used in the field of confidential information and file anti-counterfeiting.

Deep-blue emissive Cs3Cu2I5 perovskites nanocrystals with 96.6% quantum yield via InI3-assisted synthesis for light-emitting device and fluorescent ink applications

Lead-free metal halide perovskites are promising materials for future optoelectronic application, which have recently attracted great attention for their environmental-friendliness and excellent light emission properties. However, the development of deep-blue emission lead-free halide perovskite nanocrystal is still far behind in performance in comparison with its red/green counterparts. Herein, the lead-free Cs3Cu2I5 nanocrystals are prepared via a modified hot-injection strategy. By adding InI3 as precursor, the synthesized Cs3Cu2I5 single-phase nanocrystals show a bright deep-blue emission peaked at ~440 nm, with a record high photoluminescence quantum yield (PL QY) up to 96.6% at an optimized InI3 content of 0.15 mmol. The InI3 additive contributes to the high PL QY through both iodide vacancy reparation of I- ions and size-controlled growth of In3+ ions. First principle calculations reveal that the broadband blue emission originates from self-trapped excitons in Cs3Cu2I5, which are formed due to the excited-state lattice expansion and Cu-I bond lengthening of [Cu2I5]3- cluster under light excitation. The good stabilities of these Cs3Cu2I5 nanocrystals against heat, water, UV irradiation and environmental storage are also investigated experimentally and theoretically in detail. For application demonstration, light-emitting devices are manufactured by using these Cs3Cu2I5 nanocrystals powder as phosphor, which exhibit good working stability with a half-lifetime over 300 h. Besides, the Cs3Cu2I5 nanocrystals solution is also utilized as fluorescent ink, and the printed patterns can maintain anti-counterfeiting features even after treatment by heating and long-term environmental storage, indicating the robustness of these Cs3Cu2I5 nanocrystals for potential anti-counterfeiting application.

Dual-color dynamic anti-counterfeiting labels with persistent emission after visible excitation allowing smartphone authentication

A significant impediment to the deployment of anti-counterfeiting technologies is the reliance on specialized hardware. Here, anti-counterfeiting labels are developed that are both excited and detected using a smartphone. The persistent luminescence pattern and color changes on the timescale of hundreds of milliseconds to seconds. The labels can be authenticated by comparing still images from the red and green channels of video acquired at known times after flashlight excitation against expected reference patterns. The labels are based on a green-emitting SrAl2O4: Eu2+,Dy3+ (SAED), and red-emitting CaS:Eu2+ phosphors whose lifetimes are varied: (i) for SAED from 0.5 to 11.7 s by annealing the commercial material in air; and (ii) CaS:Eu2+ from 0.1 to 0.6 s by varying the dopant concentration. Examples of anti-counterfeiting labels exhibiting changing emission patterns and colors on a seven-segment display, barcode, and emoji are demonstrated. These results demonstrate that phosphors with visible absorption and tunable persistent luminescence lifetimes on the order of hundreds of milliseconds to seconds are attractive for anti-counterfeiting applications as they allow authentication to be performed using only a smartphone. Further development should allow richer color shifts and enhancement of security by embedding further covert anti-counterfeiting features.

Detection of Anti-Counterfeiting Markers through Permittivity Maps Using a Micrometer Scale near Field Scanning Microwave Microscope.

This paper describes the use of microwave technology to identify anti-counterfeiting markers on banknotes. The proposed method is based on a robust near-field scanning microwave microscope specially developed to measure permittivity maps of heterogeneous paper specimens at the micrometer scale. The equipment has a built-in vector network analyzer to measure the reflection response of a near-field coaxial probe, which makes it a standalone and portable device. A new approach employing the information of a displacement laser and the cavity perturbation technique was used to determine the relationship between the dielectric properties of the specimens and the resonance response of the probe, avoiding the use of distance-following techniques. The accuracy of the dielectric measurements was evaluated through a comparative study with other well-established cavity methods, revealing uncertainties lower than 5%, very similar to the accuracy reported by other more sophisticated setups. The device was employed to determine the dielectric map of a watermark on a 20 EUR banknote. In addition, the penetration capabilities of microwave energy allowed for the detection of the watermark when concealed behind dielectric or metallic layers. This work demonstrates the benefits of this microwave technique as a novel method for identifying anti-counterfeiting features, which opens new perspectives with which to develop optically opaque markers only traceable through this microwave technique.

Effects of Dot Configuration on Color Reproduction and Anti-counterfeiting Features

Abstract This study represents an attempt to solve the problem of color reproduction and identification for the prevention of stamp forgery. Generally, printed images are converted to halftone dot patterns by using a raster image processor. The amplitude-modulated dots of each separated color plane have a consistent shape such as conventional round, square, ellipse, or diamond shape; error diffusion occurs in frequency-modulated dots. To achieve anti-counterfeiting properties for stamp reproduction, two methods are proposed to obtain difficult-to-replicate dot structures and to provide corresponding color management methods. The first method involves arranging different dot shapes in different areas of an image. Color consistency is achieved using a virtual gray balance method. However, color differences are visible when two dot types are assigned to adjacent areas with similar colors. The second method is a two-stage screening method. The first screening stage defines different micro-regions in the image, which are then combined with the continuous-tone image again in the second screening step to assign different dot patterns to different micro-regions. This approach not only provides anti-counterfeiting ability but also ensures color consistency and allows controlling color quality using one ICC profile.

Security printing methods from a digital printing perspective

The paper discussed the secured prints by digital printing method, the paper has reviewed some new programs features provided in the field. paper problem stated to study the lack of using the new anti-counterfeiting design features in addition to future using of digital printing method as a new method in preventing prints or goods anti-counterfeiting. paper methodology followed the analytical experimental approach and theoretical one’ to solve paper problem. the objectives were to find the influence of those new innovations in doing the experimental, continue with the tests and its analysis to identify a fair and clear solution to the paper problem. in order to do that, the paper has to study the first part of paper research which focuses on one of security new programs, courtesy of agfa ... etc, and types of inks which is considered one of the most important elements in securing materials especially the UV inks, IR inks and taggant inks. The designs include covert elements used the invisible UV inks. semi-covert design elements include microtext, authenticate secure barcode, line in line special screen and other elements used visible Electro-inks. The overt elements include Guilloche, latent image, random pattern and other elements solution have also been used visible Electro-inks. Whereas, The second part focused on the analytical of the digital printing experimental which has been printed for the packages field, discussing the printed secured prints designs with a wide range of several substrates, the tests analysis were all about ink resistant to several agents, tests analysis has been implemented according to ISO Standards, the evaluation of the tests and the paper results showed that the prepared secured documents printed with UV inks on the selected digital printing corporation innovation machine (courtesy of Hewlett-Packard) have a very good performance in durability even with the hard tests which carried out on the printed samples. Recommendation included that the security digital printing and the new digital program features, both of them have an excellent opportunity in securing a very large sectors of low valued documents in addition to some of the valued documents except the forensic features which are not available by the digital printing yet.

Lifetime-tunable organic persistent room-temperature phosphorescent salts for large-area security printing

Organic persistent room-temperature phosphorescent (RTP) materials are promising for applications requiring the secure recording and anti-counterfeiting features owing to their appealing optical properties. Several critical challenges, such as the difficulty to obtain high-quality patterns over large areas and low security levels, need to be addressed to meet the requirements for commercial purpose. Here, we prepared a series of quaternary phosphonium salts with different alkyl chains, which showed interesting organic persistent RTP. The ionic characteristics and the alkyl chains of these molecules impart abundant weak intermolecular interactions. This confers the molecules a high crystallinity, which helps to preserve the persistent RTP properties and cover large areas. Moreover, the RTP lifetime of these organic salts varies over a wide range (1.27 to 884.71 ms) and can be tuned by simply changing the alkyl chain length and counterions, which opens new possibilities in multi-level information encryption applications. It is believed that the engineering of organic salts with tunable persistent RTP lifetimes and large-area printing can promote early-stage demonstrations of security applications into mature commercialization.

Multiple Anti-Counterfeiting Composite Film Based on Cholesteric Liquid Crystal and QD Materials.

A composite film with multiple anti-counterfeiting features was demonstrated by superposing quantum dots (QDs) polymer matrix (film A) and cholesteric liquid crystal film (film B) together. The first-line and second-line anti-counterfeiting characteristics were successfully implemented by employing thermochromic, angular photochromic, and circularly polarized discoloration of film B, respectively. By initiatively utilizing the different relative positions between the fluorescence emission peak (λem) of film A and the central selective reflection wavelength (λm) of film B at different temperatures, which resulted in changes in the fluorescence spectra or the different presence of latent patterns, the most important third-line anti-counterfeiting feature was successfully achieved.

Additive printing of recyclable anti-counterfeiting patterns with sol-gel cellulose nanocrystal inks.

The assembly of cellulose nanocrystals (CNCs) that produce attractive structural color shows great potential in anti-counterfeiting application, but their processability and recyclability remain unsatisfactory due to the strong hydrogen bonds between CNCs. For the first time, optical anti-counterfeiting patterns are obtained by additive printing of surface-functionalized CNC inks (CNC-DC5700-NPES). The surface-functionalized CNC inks are prepared by sequential modification of CNCs with organosilane (DC5700) and polyoxyethylene ether (NPES), which show good flowability under shearing force and transform into a gel-like phase rapidly after printing, making possible ink-jet printing without additives. The printed patterns are transparent under natural light but show vivid interference color, showing anti-counterfeiting features between crossed polarizers. The texture and optical properties of the printed patterns can be facilely controlled by tuning the printing parameters, such as nozzle diameter, writing angle, and filling width. Moreover, the CNC-DC5700-NPES patterns with a core-shell structure could be collected in various solvents and reprinted after removing solvents. This work provided a new pathway for the preparation of optical anti-counterfeiting patterns from biomass resources.

Vegetable oils based UV-luminescent ink for screen printed anti-counterfeiting marking

In this work, a new anti-counterfeiting feature relying on invisible fluorescent pattern printed with vegetable-oil-based inks were reported. Soybean oil (SBO) and tung oil (TO) were used as all the vehicle materials with low-cost, VOC-free and renewable characteristics, and grinding with ultraviolet luminescent pigment and specific additives to obtain the synthesized ink. A series of physical properties of the inks with different mixing ratios were investigated. It was found that the formulations of 75 wt.% vehicles, 15 wt.% fluorescent pigments, 3 wt.% fluorescent whitening agents, 2 wt.% ink driers, 2 wt.% defoaming agents, 2 wt.% dispersing agents, and 1 wt.% antioxidants (BHT) showed highly performance on the stability, dryness, acid and alkali resistance. More importantly, the desired-viscosity (3000 ∼ 4000 mPa·s) inks were applied on the coated paper to obtain invisible geometric designs by screen printing technology, which showed bright blue fluorescence under 365 nm UV-light irradiation. Therefore, by applying the vegetable-oil-based ink in fluorescent security marking, the information in images could be protected in such a simple and green way that was convenient to observe and verify. It exhibited the wide potentials on the anti-counterfeiting printing and commodity packaging.

A New Anti-counterfeiting Feature Relying on Invisible Non-toxic Fluorescent Carbon Dots

Fluorescent patterning has attracted a great deal of attention owing to its potential applications in different areas in particular anti-counterfeiting technology. Fluorescent carbon dots (CDs) as a type of fluorescent dyes can be used in invisible patterning due to their remarkable optical properties. This study attempts to introduce green fluorescent CDs as a promising factor in textile coding. Accordingly, a new green source opted to prepare CDs using the hydrothermal approach. Moreover, toxicity assays were performed to prove the safety of these carbon-based nanoparticles for humanity. They were also conjugated with cotton fiber successfully. Therefore, these green prepared CDs are promising for security labeling in the textile industry.

A Lightweight RFID Mutual Authentication Protocol with PUF.

Radio frequency identification is one of the key techniques for Internet of Things, which has been widely adopted in many applications for identification. However, there exist various security and privacy issues in radio frequency identification (RFID) systems. Particularly, one of the most serious threats is to clone tags for the goal of counterfeiting goods, which causes great loss and danger to customers. To solve these issues, lots of authentication protocols are proposed based on physical unclonable functions that can ensure an anti-counterfeiting feature. However, most of the existing schemes require secret parameters to be stored in tags, which are vulnerable to physical attacks that can further lead to the breach of forward secrecy. Furthermore, as far as we know, none of the existing schemes are able to solve the security and privacy problems with good scalability. Since many existing schemes rely on exhaustive searches of the backend server to validate a tag and they are not scalable for applications with a large scale database. Hence, in this paper, we propose a lightweight RFID mutual authentication protocol with physically unclonable functions (PUFs). The performance analysis shows that our proposed scheme can ensure security and privacy efficiently in a scalable way.

Dynamic anti-counterfeiting security features using multicolor dianthryl sulfoxides.

A new concept for difficult-to-replicate security inks for use in advanced anti-counterfeiting applications is presented. Inks fabricated from a mixture of photoactive dyes result in a unique fluorescent color upon irradiation that differs from the starting fluorescence. The dyes are substituted 9,9'-dianthryl sulfoxides that undergo photochemical extrusion of a sulfoxide moiety (SO) to produce emissive red, blue, and green emitters. The resulting emissive feature has specific Commission international de l'éclairage (CIE) coordinates that are used for authentication. Additionally, the temporal evolution of the fluorescence can be monitored, introducing a dynamic nature to these security features. The three compounds show different rates of photoconversion dependent on the irradiation wavelength, allowing selective wavelengths for activation to be used for additional security. CIE coordinates can be extracted from patches containing the three compounds using an inexpensive, commercially available smartphone application (app) and compared against a known value to confirm the validity of the method.

Embedding anti-counterfeiting features in metallic components via multiple material additive manufacturing

The aerospace, automotive and medical industries are suffering from significant number of counterfeited metallic products that not only have caused financial losses but also endanger lives. The rapid development of additive manufacturing technologies makes such a situation even worse. In this investigation, we successfully applied a novel hybrid powder delivery selective laser melting (SLM) approach to embed dissimilar tagging material (Cu10Sn copper alloy) safety features (e.g. QR code) into metallic components made of 316 L stainless steel. X-ray imaging was found to be a suitable method for the identification of the embedded safety features up to 15 mm in depth. X-ray fluorescence was used for the chemical composition identification of the imbedded security tagging material. A criterion for the selection of tagging material, its dimensions and imbedding depth is proposed. The multiple material SLM technology was shown to offer the potential to be integrated into metallic component production for embedding anti-counterfeiting features.