Marker based on self-pleated texture on surface of liquid crystal droplet and generation method, and anti-counterfeiting material

Abstract

The present application proposes a technology of taking the surface self-pleated texture pattern of cholesteric liquid crystal core-shell droplet as the artificial fingerprint information anti-counterfeiting mark. The artificial fingerprint is formed by micro-nano three-dimensional microstructure, and the fingerprint feature of each droplet has high randomness and unpredictability, so it is unclonable and uncopyable, and has high security. The artificial fingerprint texture on the surface of the droplet has similar detail features (such as end point, bifurcation point, line, etc.) and overall features (such as arch, ring, spiral, etc.) to human fingerprints, and has higher information density. The existing commercial fingerprint optical identification hardware device can be used for verification, so as to reduce the application cost while ensuring the identification accuracy. Based on different security application scenarios, the liquid crystal droplet with artificial fingerprint can be solidified into particles and loaded into various materials or objects as identification devices, which is easy to integrate and has broad application prospect.

Description

Technical Field

[0001] This invention belongs to the field of anti-counterfeiting materials technology, specifically relating to an identifier based on the self-wrinkled texture of liquid crystal droplet surface and its generation method, as well as anti-counterfeiting materials. Background Technology

[0002] Textured patterns are widely found in nature, especially in biological tissues and surface structures, such as human skin, plant leaves, insect wings, and animal skin and scales. These textures are formed through biological and physical mechanisms and possess specific functions, such as increasing surface area, enhancing grip, hydrophobicity, defensive capabilities, and optical effects. Fingerprints, with their unique textured patterns on the epidermis of human fingers, are highly unique and stable biometrics, thus widely used in information anti-counterfeiting and identity verification. Inspired by this, developing anti-counterfeiting identification devices based on textured patterns as artificial fingerprints has significant application value.

[0003] Human fingerprints, with their high uniqueness and lifelong immutability, are widely used in anti-counterfeiting, encryption, and identity verification. However, with advancements in imitation technologies such as high-precision silicone molds, the risk of fingerprint duplication and forgery has significantly increased. Furthermore, once fingerprint information is leaked, its unalterable nature poses a long-term threat to user privacy and security. To address these challenges, anti-counterfeiting devices based on folded textures as artificial fingerprints are emerging. This new anti-counterfeiting technology effectively addresses the risk of biometric data leakage while maintaining high security. This type of technology uses various methods to create random and unique folded texture patterns on material surfaces as anti-counterfeiting markers. Although advanced technologies can generate artificial fingerprint textures with randomness and certain characteristics (uniqueness and identifiability), these textures generally suffer from low information density (lower detail complexity than human fingerprints), high manufacturing difficulty, high cost, and difficulty in guaranteeing accurate identification. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides an identifier based on the self-wrinkled texture of liquid crystal droplet surface, a method for generating such an identifier, and an anti-counterfeiting material.

[0005] The technical problem to be solved by this invention is achieved through the following technical solution:

[0006] This invention provides a method for generating an identifier based on a self-wrinkled texture on the surface of a liquid crystal droplet, comprising:

[0007] A mixed solution having at least one liquid crystal droplet is obtained; the at least one liquid crystal droplet is suspended in the mixed solution, each liquid crystal droplet has a core-shell spherical structure, and each liquid crystal droplet comprises a droplet as a shell and at least one droplet located within the shell as a core, wherein a cholesteric liquid crystal mixed solution is present between the shell and the core.

[0008] By adjusting the attribute information and / or illumination mode of each liquid crystal droplet, the texture features of the central region of the lower surface of the liquid crystal droplet along the direction of gravity are changed; wherein, the central region of the lower surface of each liquid crystal droplet is the identification region of the liquid crystal droplet;

[0009] An in-situ curing process is performed on at least one liquid crystal droplet with altered texture features or a mixed solution containing at least one liquid crystal droplet with altered texture features to obtain an identifier based on the self-wrinkled texture of the liquid crystal droplet surface, having at least one liquid crystal droplet particle; wherein, the texture features of the identifier region of the at least one liquid crystal droplet serve as the identifier information of the identifier, and the texture features of the identifier region of different liquid crystal droplets are different, and the texture of the identifier region of each liquid crystal droplet contains the texture features of a human fingerprint.

[0010] The present invention also provides an identifier based on the self-wrinkled texture of a liquid crystal droplet surface. The identifier comprises: at least one liquid crystal droplet particle, which is obtained by in-situ curing of at least one liquid crystal droplet with altered texture features suspended in a mixed solution. The central region of the lower surface of each liquid crystal droplet with altered texture features along the direction of gravity is the identifier region of the liquid crystal droplet. The texture features of the identifier region of each liquid crystal droplet with altered texture features are obtained by adjusting the attribute information and / or illumination mode of the liquid crystal droplet. The texture features of the identifier region of the at least one liquid crystal droplet serve as anti-counterfeiting identification information of the identifier. Furthermore, the texture features of the identifier region of different liquid crystal droplets are different, and the texture of the identifier region of each liquid crystal droplet contains the texture features of a human fingerprint.

[0011] The present invention also provides an anti-counterfeiting material, comprising: the above-mentioned identifier based on the self-wrinkling texture of liquid crystal droplet surface and a material for serving as a carrier of the identifier.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] This invention alters the texture features of the self-folded stripes on the surface of liquid crystal droplets by adjusting the attribute information and / or illumination method of each droplet. This results in the texture at the central region of the lower surface of each droplet containing the texture features of a human fingerprint, thus creating an artificial texture similar to a human fingerprint on the droplet surface. This artificial texture possesses detailed features (such as endpoints, bifurcation points, and ridges) and overall features (such as arched patterns, ring patterns, and spiral patterns) similar to human fingerprints, resulting in higher complexity. Furthermore, methods for recognizing human fingerprints can be applied to recognizing artificial textures, and it can be verified using existing commercial fingerprint optical recognition hardware. This not only improves the information density of the artificial texture but also enhances its recognition accuracy. Moreover, since the artificial texture is prepared by adjusting only the attribute information and / or illumination method of the liquid crystal droplets, and the materials involved are already commercially available on a large scale in the information display industry, the preparation is simple and cost-effective. Furthermore, the artificial texture features created on the droplet surface by this invention possess a high degree of randomness and unpredictability, combining randomness and distinctiveness, thus making them unclonable and unreplicable, and providing high security. Moreover, the artificial texture features created on the droplet surface by this invention vary depending on the adjustment of the liquid crystal droplet's properties and / or the intensity of illumination, thus enabling the creation of rich and diverse artificial textures. Furthermore, this invention obtains the identifier through in-situ solidification of the droplet, allowing the identifier to be encapsulated in various materials, thus showing broad application prospects in anti-counterfeiting, encryption, and identification fields.

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating a method for generating an identifier based on a self-wrinkled texture on the surface of a liquid crystal droplet, as provided in an embodiment of the present invention.

[0016] Figure 2 These are schematic diagrams, actual side views, and actual top views of a liquid crystal droplet with a core-shell spherical structure provided in an embodiment of the present invention.

[0017] Figure 3 This is a typical microscopic texture image of the upper surface, side surface, and lower surface of a liquid crystal droplet with a core-shell spherical structure provided in an embodiment of the present invention;

[0018] Figure 4 This is a schematic diagram of different liquid crystal droplets with an overall size of 200 micrometers and core sizes of 168.8 micrometers, 188.1 micrometers, and 194.5 micrometers, respectively, provided in an embodiment of the present invention;

[0019] Figure 5This is a schematic diagram of the microtexture patterns on the lower surface of different liquid crystal droplets with an overall size of 200 micrometers and cholesteric chiral dopants in the cholesteric liquid crystal mixture solution inside the shell at weight ratios of 1%, 2%, and 3%, respectively, provided in an embodiment of the present invention.

[0020] Figure 6 This is a schematic diagram of the microscopic texture pattern on the lower surface of the liquid crystal droplets at different irradiation stages when multiple liquid crystal droplets of the same size are uniformly irradiated using an intermittent illumination method with multiple irradiation cycles, as provided in an embodiment of the present invention.

[0021] Figure 7 This is a schematic diagram of the texture patterns on the lower surface of eight different liquid crystal droplets provided in the embodiments of the present invention when they are in a steady state (or metastable state);

[0022] Figure 8 This is a schematic diagram of the texture patterns on the lower surface of six different liquid crystal droplets provided in the embodiments of the present invention, which are solidified at a certain moment during the evolution process.

[0023] Figure 9 This is an exemplary front view of a thin film obtained by in-situ curing and other treatments of a mixed solution and a large number of liquid crystal droplets with altered texture features suspended in the mixed solution, as provided in an embodiment of the present invention.

[0024] Figure 10 This is a statistical chart of ridge density data from 300 artificial fingerprint images provided in an embodiment of the present invention;

[0025] Figure 11 This is a statistical chart of the non-cloning (Hamming distance) data of 300 artificial fingerprint images provided in an embodiment of the present invention. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0027] Figure 1 This is a flowchart illustrating a method for generating an identifier based on a self-wrinkled texture on the surface of a liquid crystal droplet, as provided in an embodiment of the present invention. Figure 1 As shown, the method includes:

[0028] S101. Obtain a mixed solution having at least one liquid crystal droplet; at least one liquid crystal droplet is suspended in the mixed solution, each liquid crystal droplet has a core-shell spherical structure, and each liquid crystal droplet includes a droplet as a shell and at least one droplet located inside the shell as a core, with a cholesteric liquid crystal mixed solution between the shell and the core.

[0029] Here, liquid crystal droplets are prepared using existing coaxial fluid focusing glass capillary microfluidic technology or laser injection technology.

[0030] For example, Figure 2 The diagram shows the schematic side view, actual side view, and actual top view of a liquid crystal droplet with a core-shell spherical structure. Figure 2 The liquid crystal droplet shown contains a core. Specifically, in Figure 2 In the figure, (a) is a side view of a liquid crystal droplet with a core-shell spherical structure, (b) is a real side view of a liquid crystal droplet with the core-shell spherical structure of (a), and (c) is a real top view of a liquid crystal droplet with the core-shell spherical structure of (a). Figure 2 In the diagram, 1 represents the droplet nucleus (i.e., the core of the liquid crystal droplet), 2 represents the droplet shell (i.e., the outer shell of the liquid crystal droplet), 3 represents the mixed solution surrounding the liquid crystal droplet, 6 represents the upper surface of the liquid crystal droplet along the direction of gravity, and 7 represents the lower surface of the liquid crystal droplet along the direction of gravity.

[0031] Here, the cholesteric phase liquid crystal mixture solution comprises: liquid crystal, cholesteric phase chiral dopant, UV-curable material, and photoinitiator. For example, the liquid crystal can be E7 liquid crystal, the cholesteric phase chiral dopant can be R811, the photoinitiator can be Irgacure 651, and the UV-curable material can be RM257. The weight ratio of each component can be set according to actual needs. For example, the weight ratios of the cholesteric phase chiral dopant, UV-curable material, and photoinitiator range from 0.1% to 20%, 1% to 25%, and 0.1% to 10%, respectively. Exemplarily, the weight ratios of the cholesteric phase chiral dopant, UV-curable material, and photoinitiator can be 3%, 15%, and 5%, respectively.

[0032] Here, the mixed solution containing the liquid crystal droplets can be an aqueous solution of sodium dodecyl sulfate (SDS), and the weight ratio of the sodium dodecyl sulfate aqueous solution can range from 0.1% to 20%. For example, the mixed solution containing the liquid crystal droplets can be an aqueous solution of sodium dodecyl sulfate with a weight ratio of 2%.

[0033] Here, the droplet core also contains a solution, for example, which can be an aqueous solution of polyvinyl alcohol, with a weight ratio ranging from 0.5% to 80%. For example, the solution in the droplet core can be an aqueous solution of polyvinyl alcohol (PVA) with a weight ratio of 1%.

[0034] Here, the size of each liquid crystal droplet ranges from micrometers to centimeters, and the specific size can be selected according to actual needs.

[0035] In some embodiments, the shell size of at least one liquid crystal droplet described above may be the same or different, and the present invention does not limit this.

[0036] S102. By adjusting the attribute information and / or illumination mode of each liquid crystal droplet, the texture features of the central region of the lower surface of the liquid crystal droplet along the direction of gravity are changed; wherein, the central region of the lower surface of each liquid crystal droplet is the identification region of the liquid crystal droplet.

[0037] S103. Perform in-situ curing processing on at least one liquid crystal droplet with altered texture features or a mixed solution containing at least one liquid crystal droplet with altered texture features to obtain an identifier based on the self-wrinkled texture of the liquid crystal droplet surface with at least one liquid crystal droplet particle; wherein, the texture features of the identifier region of at least one liquid crystal droplet serve as the anti-counterfeiting identification information of the identifier, and the texture features of the identifier regions of different liquid crystal droplets are different, and the texture of the identifier region of each liquid crystal droplet contains the texture features of human fingerprints.

[0038] Here, the texture of the marking area of ​​each liquid crystal droplet contains texture features similar to human fingerprints, that is, it has detailed features and overall features similar to human fingerprints.

[0039] In this invention, liquid crystal droplets are stably suspended in a mixed solution. Both the mixed solution in which the liquid crystal droplets are suspended and the aqueous solution in the droplet core are doped with surfactants to serve two purposes: firstly, to reduce interfacial tension and maintain the structural stability of the liquid crystal droplets; and secondly, to provide specific anchoring conditions and anchoring strength for the liquid crystals within the droplet shell. These anchoring conditions include horizontal and vertical anchoring conditions, which cause the liquid crystal molecules to tend to align parallel or perpendicular to the liquid interface. The anchoring strength determines the degree to which the liquid crystal molecules align along a specific direction of the interface. The mixed solution in which the liquid crystal droplets are suspended and the aqueous solution in the droplet core each possess horizontal or vertical anchoring conditions. When the inner and outer interfaces of the liquid crystal droplet shell have different anchoring conditions, the droplet is said to have mixed anchoring conditions. Mixed anchoring conditions are the typical anchoring conditions for liquid crystal droplets in this invention.

[0040] The inventors of this invention discovered that within the shell of the aforementioned liquid crystal droplet, the arrangement of liquid crystal molecules is influenced by a combination of factors, including the geometric constraints of the inner and outer spherical interfaces, anchoring conditions and anchoring strength, interfacial tension, shell thickness, and the elastic forces and helical twisting forces between liquid crystal molecules in the cholesteric phase liquid crystal. Under the combined effect of these factors, the liquid crystal molecules within the droplet shell adjust their own arrangement to bring the total energy of the liquid crystal droplet system towards a low-energy state, thus driving the liquid crystal droplet system from an unsteady state to a steady state (or metastable state). Based on the arrangement of liquid crystal molecules within the liquid crystal droplet shell, undulating wrinkled stripe textures can spontaneously form at the surface interface of the liquid crystal droplet; along the direction of gravity, the top and bottom interfaces of the liquid crystal droplet are referred to as the upper surface and lower surface, respectively. In particular, the lower interface of the liquid crystal droplet exhibits rich wrinkled stripe texture patterns, displaying obvious regularity and characteristics. For example, Figure 3 Figure (a) shows a typical microstructure of the upper surface of a liquid crystal droplet with a core-shell spherical structure; Figure (b) shows a typical microstructure of the side surface of the same liquid crystal droplet; and Figure (c) shows a typical microstructure of the lower surface of the same liquid crystal droplet. Figure 3 As shown, the edge regions of the texture patterns on the upper and lower surfaces are concentric circular wrinkled stripes, while the side surfaces have parallel circular wrinkled stripes. It can be observed that these concentric circular stripes extend from the top edge of the droplet to the bottom edge. The texture pattern in the central region of the lower surface of the liquid crystal droplet exhibits high randomness; therefore, the texture pattern in the central region of the lower surface of the liquid crystal droplet can be used as the marking region of the generated marker. Furthermore, the process of spontaneous energy minimization in the liquid crystal droplet system, or the process of altering the arrangement of liquid crystal molecules through external intervention, can macroscopically manifest as the dynamic evolution of the wrinkled texture on the droplet surface. Based on this, the present invention uses S102 to change the texture characteristics of the self-wrinkled stripes on the surface of the liquid crystal droplet, thereby controlling the texture characteristics of the self-wrinkled stripes on the lower surface of the liquid crystal droplet, and thus generating a marker based on the self-wrinkled texture of the liquid crystal droplet surface.

[0041] In some embodiments, S102 above can be implemented as step S1021:

[0042] S1021. By adjusting the first attribute information of each liquid crystal droplet, the area of ​​the marking region of the liquid crystal droplet is increased; wherein, when the area of ​​the marking region increases, the information capacity of the marking region increases.

[0043] Specifically, the area of ​​the identification region of the liquid crystal droplet is increased by increasing the first attribute information of each liquid crystal droplet.

[0044] Specifically, the first attribute information can be the size of the nucleus of each liquid crystal droplet, the number of nuclei of each liquid crystal droplet, or both the size and number of nuclei of each liquid crystal droplet. When the size and / or number of nuclei of a liquid crystal droplet increases, the area of ​​the self-wrinkled stripe pattern on the surface of the liquid crystal droplet that can serve as the identifying region of the liquid crystal droplet increases, that is, the area of ​​the texture pattern at the center of the lower surface of the liquid crystal droplet increases.

[0045] For example, Figure 4 The diagram shows different liquid crystal droplets with an overall size of 200 micrometers and core sizes of 168.8 micrometers, 188.1 micrometers, and 194.5 micrometers, respectively. The material composition of the cholesteric liquid crystal mixture between the shell and the core of the liquid crystal droplet is: E7, 3% by weight of R811, 15% by weight of RM257, and 5% by weight of Irgacure651; the core of the droplet contains 1% by weight of PVA aqueous solution, and the mixture containing the liquid crystal droplet contains 2% by weight of SDS aqueous solution.

[0046] Specifically, in Figure 4 In the figures, (a) the upper image is a side view of a liquid crystal droplet with a core size of 168.8 micrometers, and (b) the lower image shows region 11, which is the microtexture pattern at the center of the lower surface of the liquid crystal droplet with a core size of 168.8 micrometers; (c) the upper image is a side view of a liquid crystal droplet with a core size of 188.1 micrometers, and (c) the lower image shows region 15, which is the microtexture pattern at the center of the lower surface of the liquid crystal droplet with a core size of 194.5 micrometers. Due to the density difference between the droplet core and the shell, the droplet core is in close contact with the inner wall of the upper interface of the liquid crystal droplet. The lower interface of the liquid crystal droplet, i.e., the interface downward along the direction of gravity, is the characteristic identification area (identification area) of the liquid crystal droplet. Obviously, by increasing the size of the droplet nucleus in the liquid crystal droplet, the area of ​​the texture image at the center of the lower surface of the liquid crystal droplet can be increased, thereby increasing the area of ​​the feature recognition region of the liquid crystal droplet.

[0047] In some embodiments, the above-mentioned S102 can be implemented as step S1022:

[0048] S1022. By adjusting the second attribute information of each liquid crystal droplet, the texture richness of the marking area of ​​the liquid crystal droplet is increased; wherein, when the texture richness of the marking area increases, the information density per unit area of ​​the marking area increases.

[0049] Specifically, by increasing the second attribute information of each liquid crystal droplet, the texture richness of the identification area of ​​the liquid crystal droplet is increased.

[0050] Specifically, the second attribute information can be the doping concentration (weight ratio) of the cholesteric chiral dopant in the cholesteric liquid crystal mixed solution, the helical twisting force of the cholesteric chiral dopant, the enantiomeric excess value of the cholesteric chiral dopant, or any combination of these three parameters. Among them, the helical twisting force of different types of cholesteric chiral dopant is different.

[0051] For example, when increasing the texture richness of the marking region of a liquid crystal droplet by increasing the weight ratio of the cholesteric chiral dopant, the upper limit of the weight ratio of the cholesteric chiral dopant is in the range of 13% to 25%. For example, the upper limit of the weight ratio of the cholesteric chiral dopant in a cholesteric liquid crystal mixture is 15%.

[0052] For example, Figure 5 This is a schematic diagram of the microtexture patterns on the lower surface of different liquid crystal droplets with an overall size of 200 micrometers and cholesteric chiral dopants in the cholesteric liquid crystal mixture solution within the shell at weight ratios of 1%, 2%, 3%, and 4%. The composition of other materials in the cholesteric liquid crystal mixture solution is: E7, 15% RM257 by weight, and 5% Irgacure 651 by weight; the droplet core contains 1% PVA aqueous solution by weight, and the mixture solution containing the liquid crystal droplets contains 2% SDS aqueous solution by weight. Specifically, in... Figure 5 In Figure (a), region 17 shows the texture pattern of the central region of the lower surface of a liquid crystal droplet with a cholesteric chiral dopant concentration of 1% by weight; region 18 shows the texture pattern of the central region of the lower surface of a liquid crystal droplet with a cholesteric chiral dopant concentration of 2% by weight; and region 19 shows the texture pattern of the central region of the lower surface of a liquid crystal droplet with a cholesteric chiral dopant concentration of 3% by weight. Comparison reveals that although randomly formed wrinkled texture patterns are observed in the central region of the lower surface of all three droplets, it is evident that as the concentration of the cholesteric chiral dopant increases, the spacing of the wrinkled stripes in regions 17, 18, and 19 narrows, and the texture patterns become more detailed and complex. The change in the concentration of the cholesteric chiral dopant essentially alters the pitch formed by the helical twisting arrangement between liquid crystal molecules, thereby controlling the texture characteristics of the central region of the lower surface of the liquid crystal droplet.

[0053] In some embodiments, S102 above can be implemented as step S1023:

[0054] S1023. By adjusting the illumination process (light intensity, frequency, total energy) of each liquid crystal droplet, the overall texture pattern complexity of the marking area of ​​the liquid crystal droplet is increased.

[0055] Specifically, by making the illumination mode of each liquid crystal droplet an intermittent illumination mode containing multiple illumination cycles, the number of arc-shaped patterns in the marking area of ​​the liquid crystal droplet is reduced, while the number of annular and spiral patterns is generated and increased; wherein, the annular and spiral patterns are evolved from the arc-shaped patterns; wherein, each illumination cycle consists of illumination time and pause time.

[0056] Here, the irradiation time or pause time in different irradiation cycles can be the same or different.

[0057] In some embodiments, when the material system of the liquid crystal droplet belongs to a first preset material system, that is, when the type of liquid crystal in the cholesteric phase liquid crystal mixture solution of the liquid crystal droplet belongs to a first preset liquid crystal type, and the type of cholesteric chiral dopant in the cholesteric phase liquid crystal mixture solution of the liquid crystal droplet belongs to a first preset dopant type, the number of repetitions of the irradiation cycle is negatively correlated with the number of arc-shaped patterns in the marking region of the liquid crystal droplet, and positively correlated with the number of annular and spiral patterns in the marking region of the liquid crystal droplet. Both the light intensity and the light frequency are positively correlated with the evolution rate of the arc-shaped patterns towards the annular or spiral patterns.

[0058] In some embodiments, when the material system of the liquid crystal droplet belongs to a second preset material system, that is, when the type of liquid crystal in the cholesteric liquid crystal mixture solution of the liquid crystal droplet belongs to a second preset liquid crystal type, and the type of cholesteric chiral dopant in the cholesteric liquid crystal mixture solution of the liquid crystal droplet belongs to a second preset dopant type, the number of repetitions of the irradiation cycle is positively correlated with the number of arc-shaped patterns in the marking region of the liquid crystal droplet, and negatively correlated with the number of annular and spiral patterns in the marking region of the liquid crystal droplet.

[0059] Here, the first preset liquid crystal type and the first preset dopant type, as well as the second preset liquid crystal type and the second preset dopant type, can all be obtained through actual testing. For example, when the liquid crystal in the cholesteric phase liquid crystal mixture of a liquid crystal droplet is E7 liquid crystal, and the cholesteric chiral dopant in the cholesteric phase liquid crystal mixture of the liquid crystal droplet is R811, the number of repetitions of the irradiation cycle is negatively correlated with the number of arc-shaped patterns in the marking region of the liquid crystal droplet, and positively correlated with the number of annular and spiral patterns in the marking region of the liquid crystal droplet.

[0060] For example, Figure 6This diagram illustrates the microscopic texture patterns on the lower surface of multiple identical liquid crystal droplets during different irradiation stages, using an intermittent illumination method comprising multiple irradiation cycles. The overall size of the liquid crystal droplets is 200 micrometers. The weight percentage of R811 in the cholesteric liquid crystal mixture within the droplet shell is 3%. The other components in the cholesteric liquid crystal mixture are: E7, 15% RM257, and 5% Irgacure 651. The droplet core contains a 1% PVA aqueous solution, and the mixture containing the liquid crystal droplets contains a 2% SDS aqueous solution. The intermittent illumination method includes a first irradiation cycle, a second irradiation cycle, and a third irradiation cycle, for a total of three irradiation cycles, with each cycle consisting of three repetitions. The first irradiation cycle involves 0.5 minutes of UV irradiation followed by a 1-minute pause; the second irradiation cycle involves 5 minutes of UV irradiation followed by a 5-minute pause; and the third irradiation cycle involves 0.5 minutes of UV irradiation followed by a 10-minute pause.

[0061] Specifically, in Figure 6 In the figures, (a) shows the microscopic texture patterns on the lower surfaces of multiple liquid crystal droplets of the same size that have not been exposed to ultraviolet light; (b) shows the microscopic texture patterns on the lower surfaces of multiple liquid crystal droplets of the same size that have undergone the first illumination cycle; (c) shows the microscopic texture patterns on the lower surfaces of multiple liquid crystal droplets of the same size that have undergone the first and second illumination cycles; and (d) shows the microscopic texture patterns on the lower surfaces of multiple liquid crystal droplets of the same size that have undergone the first, second, and third illumination cycles. After three illumination cycles, the texture pattern in the central region of the lower surface of the liquid crystal droplets solidifies, and the shell of the liquid crystal droplets changes from a liquid state to a solid state. Figure 6 As shown, during ultraviolet (UV) irradiation, the texture pattern at the center of the lower surface of the liquid crystal droplet undergoes dynamic evolution. Specifically, the texture pattern at the center of the lower surface of the liquid crystal droplet, after being treated sequentially through the first, second, and third irradiation cycles, continuously rotates clockwise in a spiral motion. This is consistent with the chirality of the cholesteric chiral dopant in the droplet's shell (R811 is a dextrorotatory cholesteric chiral dopant). Because this texture pattern has similar overall characteristics to human fingerprints, based on the classification method of primary features of human fingerprints (arch, ring, and spiral patterns), it can be concluded that the texture features after UV irradiation change from predominantly arch-shaped patterns to predominantly ring and spiral patterns. The evolution of arch-shaped patterns into ring or spiral patterns in the texture pattern can be referred to as the evolution of the texture pattern.

[0062] Here, by adjusting the light intensity and / or light frequency, the rate at which the texture pattern evolves on the lower surface of the liquid crystal droplet can be altered. Simultaneously, when the total light energy meets the requirements of the liquid crystal droplet's material system, the texture pattern on the lower surface of the liquid crystal droplet can be solidified, thus forming a solidified texture. For example, Figure 7 and Figure 8 The image shows typical texture patterns on the lower surface of different solidified liquid crystal droplets, for comparison. Figure 6 The dynamic evolution process of the same set of liquid crystal droplet textures shown can be seen. Figure 7 and Figure 8 Liquid crystal droplets are in different evolutionary stages, and the texture patterns they exhibit have different types of characteristic information. The essence of liquid crystal droplet texture evolution is the dynamic evolution of the arrangement order of liquid crystal molecules within the droplet. From the perspective of the liquid crystal droplet system's energy, this process can be divided into transient, metastable, and steady states. Figure 7 This is a schematic diagram of the texture patterns on the lower surfaces of eight different liquid crystal droplets in a steady state (or metastable state). Figure 8 This is a schematic diagram showing the solidification of the texture patterns on the lower surfaces of six different liquid crystal droplets at a certain moment during their evolution. At this point, the liquid crystal droplets are in a transient (or transient) state. In other words, Figure 8 This is a schematic diagram showing the texture patterns on the lower surfaces of six different liquid crystal droplets in an unstable state. (By comparison...) Figure 7 and Figure 8 It can be observed that when the liquid crystal molecules in the liquid crystal droplet shell are arranged to make the system energy reach a minimum value, the texture features of the texture pattern in the central region of the lower surface of the liquid crystal droplet after solidification are richer and more regular.

[0063] In some embodiments, S102 can also be implemented as any two of the steps S1021 to S1023.

[0064] In some embodiments, S102 can also be implemented as steps S1021 to S1023.

[0065] Obviously, the present invention can adjust the detailed and overall features of the texture on the surface of liquid crystal droplets by means of structural size, material composition and ultraviolet light treatment scheme.

[0066] The modified texture features of the liquid crystal droplets, even within the same batch processed under identical conditions (with the same core-shell size, number of cores, material composition, etc.), result in distinct texture patterns in the central region of the lower surface of each droplet. This physical non-cloning (PUF) characteristic allows them to function as artificial fingerprint identifiers. Based on the needs of practical applications, the liquid crystal droplet shell, core, and solution can be separately solidified and incorporated into various packaging formats as anti-counterfeiting markers.

[0067] In some embodiments, for the above-mentioned S103, when at least one liquid crystal droplet with altered texture features in the mixed solution has been solidified in situ after step S102, the mixed solution can be further solidified by light irradiation to solidify the mixed solution and the liquid crystal droplet with altered texture features into a whole. Then, this whole is further processed to obtain an identifier, or the whole is directly used as an identifier.

[0068] In-situ curing can solidify the arrangement of liquid crystal molecules within the shell of a liquid crystal droplet at a specific time, thereby creating a long-term stable artificial fingerprint pattern in the central region of the droplet's lower surface. This pattern can then serve as a feature recognition area for the droplet. Liquid crystal droplets cured in situ are easy to integrate and can be encapsulated in various forms, showing broad application prospects in anti-counterfeiting, encryption, and identification fields.

[0069] In some embodiments, for the above-mentioned S103, when at least one liquid crystal droplet with altered texture features in the mixed solution has been solidified in situ after step S102, the obtained solidified liquid crystal droplet particles can be further processed to obtain an identifier, or the obtained solidified liquid crystal droplet particles can be directly used as an identifier.

[0070] In some embodiments, for the above-mentioned S103, if at least one liquid crystal droplet with altered texture features in the mixed solution has not been solidified after step S102, the mixed solution and the liquid crystal droplet can be solidified in situ together by light irradiation to solidify the mixed solution and the liquid crystal droplet with altered texture features into a whole. Then, this whole is further processed to obtain the identifier, or the whole is directly used as the identifier.

[0071] In some embodiments, for the above S103, if at least one liquid crystal droplet with altered texture features in the mixed solution has not solidified after step S102, only the liquid crystal droplets can be solidified in situ. Afterward, the obtained solidified liquid crystal droplet particles can be further processed to obtain an identifier. Alternatively, the obtained solidified liquid crystal droplet particles can be directly used as identifiers.

[0072] The above-mentioned curing processing methods can be selected according to the actual situation. For example, when performing in-situ curing, the total energy required for the material systems in the aforementioned examples of this invention is 420mW±5μW×6min.

[0073] For example, Figure 9This is a front view of the film obtained by in-situ curing and other treatments of a mixed solution and a large number of liquid crystal droplets with altered texture features suspended in the mixed solution. The front view of the film is the side where the lower surface of all liquid crystal droplets is located along the direction of gravity. Figure 9 The liquid crystal droplets shown are all 100 micrometers in size. The weight percentage of R811 in the cholesteric phase liquid crystal mixture within the shell is 3%. Other materials in the cholesteric phase liquid crystal mixture consist of E7, 15% RM257 by weight, and 5% Irgacure 651 by weight. The droplet core contains 1% PVA aqueous solution by weight, and the mixture containing the liquid crystal droplets contains 2% SDS aqueous solution by weight. The curing process is as follows: after treatment with 365nm ultraviolet light (420mW±5μW) for 6 minutes, the liquid crystal droplets are cured into particles with a stable texture pattern. These cured liquid crystal droplet particles are then added to a PDMS mixture (polydimethylsiloxane) and allowed to stand for 30 minutes. Finally, the PDMS mixture containing the cured liquid crystal droplet particles is placed in a vacuum oven at 50°C for 3 hours to obtain a polymer film containing a large number of cured liquid crystal droplet particles. The lower surfaces of the cured liquid crystal droplet particles face the same direction, which is the front side of the film.

[0074] This invention also provides an identifier based on the self-wrinkled texture of a liquid crystal droplet surface. This identifier is generated using the aforementioned method for generating an identifier based on the self-wrinkled texture of a liquid crystal droplet surface. The identifier comprises at least one liquid crystal droplet particle, obtained by in-situ solidification processing of at least one liquid crystal droplet with altered texture features suspended in a mixed solution. The central region of the lower surface of each texture-altered liquid crystal droplet along the direction of gravity is the identifier region of that droplet. The texture features of each texture-altered liquid crystal droplet are obtained by adjusting the attribute information and / or illumination method of the liquid crystal droplet. The texture features of the identifier region of at least one liquid crystal droplet serve as anti-counterfeiting information for the identifier. Furthermore, the texture features of the identifier regions of different liquid crystal droplets are different, and the texture of the identifier region of each liquid crystal droplet includes the texture features of a human fingerprint. For example, this identifier can be... Figure 9 The thin film shown, or Figure 9 The liquid crystal droplets are solidified into particles as shown.

[0075] In this invention, the security of the identifier is positively correlated with the number of liquid crystal droplets in the identifier. That is, by increasing the number of liquid crystal droplets in the identifier, the encryption level (security) of the identifier can be flexibly improved.

[0076] The present invention also provides an anti-counterfeiting material comprising: the above-mentioned identifier based on the self-wrinkling texture of liquid crystal droplet surface, and a material for serving as a carrier of the identifier.

[0077] For example, the anti-counterfeiting material can be a spray, paint, ink, film, fiber, adhesive, tape, etc., carrying the identifier. Any material carrying the identifier of this invention belongs to the anti-counterfeiting material described in this invention.

[0078] To verify the characteristics of the artificial fingerprint (i.e., the texture at the center region of the lower surface) of the liquid crystal droplet of the present invention, the following experiments were conducted:

[0079] Experiment 1: From Figure 9 Microscopic texture images of artificial fingerprints with different liquid crystal particles were captured in the polymer film shown, establishing an artificial fingerprint database of liquid crystal particles with a sample size of 300. Because this artificial fingerprint has similar overall features to human fingerprints, image processing analysis was performed on the texture patterns in the artificial fingerprint database based on the classification method of secondary features of human fingerprints (fingerprint minutiae, such as intersections and endpoints). The secondary feature minutiae endpoints were extracted, resulting in an average ridge density of 5.8 × 10⁻⁶ in the 300 artificial fingerprint images. 5 (Details per 25 square millimeters), specifically as follows Figure 10 As shown. In comparison, the ridge density of human fingerprints ranges from approximately 30 to 80 (minimum details per 25 square millimeters). The detail density (information density) of the artificial fingerprint from the liquid crystal droplets in this invention is four orders of magnitude higher than that of human fingerprints. The ridge density data for human fingerprints are from the document "Naser Zaeri, Minutiae-based Fingerprint Extraction and Recognition, Biometrics, 2011".

[0080] Experiment 2: A hash algorithm was used to calculate the Hamming distance between 300 images in the aforementioned artificial fingerprint database. This Hamming distance is used to measure the similarity between two images. The Hamming distance ranges from 0 to 1; a value greater than a threshold of 0.75 indicates that the two images are similar, while a value lower than the threshold of 0.75 indicates that the two images are dissimilar. (Reference) Figure 11 The Hamming distance grayscale image shown shows that the similarity of all 300 images in the database is below the threshold, thus proving that the artificial fingerprints of all liquid crystal particles in the database are unique.

[0081] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0083] In this specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. While different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce a good effect.

[0084] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for generating an identifier based on self-pleated texture of liquid crystal droplet surface, characterized by, The method comprises the following steps: obtaining a mixed solution with at least one liquid crystal droplet; each of the at least one liquid crystal droplet is suspended in the mixed solution, each liquid crystal droplet is a core-shell spherical structure, and each liquid crystal droplet comprises one liquid droplet as a shell and at least one liquid droplet as a core in the shell, and there is a cholesteric phase liquid crystal mixed solution between the shell and the core; by adjusting the attribute information and / or illumination method of each liquid crystal droplet, the texture characteristics of the lower surface center area of the liquid crystal droplet along the gravity direction are changed; wherein the lower surface center area of each liquid crystal droplet is the identification area of the liquid crystal droplet; the at least one liquid crystal droplet after the texture characteristics are changed or the mixed solution with the at least one liquid crystal droplet after the texture characteristics are changed is subjected to in-situ solidification processing to obtain a liquid crystal droplet surface self-crease texture-based identifier with at least one liquid crystal droplet particle; wherein the texture characteristics of the identification area of the at least one liquid crystal droplet serve as the anti-counterfeiting identification information of the identifier, and the texture characteristics of the identification area of different liquid crystal droplets are different, and the texture of the identification area of each liquid crystal droplet contains the texture characteristics of a human fingerprint; wherein the step of changing the texture characteristics of the lower surface center area of each liquid crystal droplet along the gravity direction by adjusting the attribute information and / or illumination method of each liquid crystal droplet comprises at least one of the following adjustment steps: a first attribute adjustment step: by adjusting the first attribute information of each liquid crystal droplet, the area of the identification area of the liquid crystal droplet is increased; wherein when the area of the identification area is increased, the information capacity of the identification area is increased; a second attribute adjustment step: by adjusting the second attribute information of each liquid crystal droplet, the texture richness of the identification area of the liquid crystal droplet is increased; wherein when the texture richness of the identification area is increased, the information density per unit area of the identification area is increased; an illumination method adjustment step: by adjusting the illumination process method of each liquid crystal droplet, the complexity of the overall texture pattern of the identification area of the liquid crystal droplet is increased; wherein when the complexity of the overall texture pattern of the identification area is increased, the types of feature information of the texture pattern of the identification area are increased.

2. The method of claim 1, wherein the liquid crystal droplet surface self- corrugation based texture is generated by a method comprising: the step of increasing the area of the identification area of the liquid crystal droplet by increasing the first attribute information of each liquid crystal droplet. the first attribute information comprises at least one of the following attribute information: the size of the core and the number of the core.

3. The method for generating a marker based on self-pleated texture of liquid crystal droplets according to claim 1 or 2, characterized in that, the step of increasing the texture richness of the identification area of the liquid crystal droplet by increasing the second attribute information of each liquid crystal droplet.

4. The method of claim 1, wherein the liquid crystal droplet surface self- corrugation based texture is generated by a method comprising: the second attribute information comprises at least one of the following attribute information: ​ 5. The method of claim 1 or 4, wherein the liquid crystal droplet surface self- corrugation based texturing is generated by a method comprising: ​ The doping concentration of the cholesteric dopant in the cholesteric liquid crystal mixed solution, the enantiomeric excess value of the cholesteric dopant, and the helical twisting power of the cholesteric dopant; wherein the helical twisting powers of different types of cholesteric dopants are different.

6. The method of claim 1, wherein the liquid crystal droplet surface self- corrugation based texture is generated by a method comprising: The method for increasing the complexity of the overall texture pattern of the identification area of the liquid crystal droplet by adjusting the light irradiation process of each liquid crystal droplet comprises: By making the light irradiation mode of each liquid crystal droplet an intermittent irradiation mode comprising a plurality of irradiation cycles, the number of arc-shaped lines in the identification area of the liquid crystal droplet is reduced, while the number of ring-shaped lines and spiral lines is generated and increased; wherein the ring-shaped lines and the spiral lines evolve from the arc-shaped lines; wherein each irradiation cycle can be repeated, and each irradiation cycle consists of an irradiation time and a pause time.

7. The method of claim 6, wherein the liquid crystal droplet surface self- corrugation based texture is generated by a method comprising: The cholesteric liquid crystal mixed solution comprises liquid crystals and cholesteric dopants; when the type of the liquid crystals belongs to a first preset liquid crystal type, and the type of the cholesteric dopants belongs to a first preset dopant type, the number of repetitions of the irradiation cycle is negatively correlated with the number of arc-shaped lines in the identification area of the liquid crystal droplet, while positively correlated with the number of ring-shaped lines and spiral lines in the identification area of the liquid crystal droplet, and the irradiation intensity and the irradiation frequency are positively correlated with the evolution speed of the arc-shaped lines to the ring-shaped lines or the spiral lines.

8. An identifier based on self-pleated surface texture of liquid crystal droplets, characterized by, The identifier is generated by the method of any one of claims 1-7, and the identifier comprises: at least one liquid crystal droplet particle obtained by in-situ solidification processing of at least one liquid crystal droplet with changed texture characteristics suspended in a mixed solution, the central area of the lower surface of each liquid crystal droplet with changed texture characteristics in the direction of gravity is the identification area of the liquid crystal droplet; the texture characteristics of the identification area of each liquid crystal droplet with changed texture characteristics are obtained by adjusting the attribute information of the liquid crystal droplet and / or the light irradiation mode, wherein the texture characteristics of the identification area of the at least one liquid crystal droplet serve as the anti-counterfeiting identification information of the identifier, and the texture characteristics of the identification area of different liquid crystal droplets are different, and the texture of the identification area of each liquid crystal droplet comprises the texture characteristics of a human fingerprint.

9. A security material, characterized in that It comprises the liquid crystal droplet surface self-pleated texture-based identifier of claim 8 and a material used as a carrier of the identifier.

Images