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

Abstract

The invention provides a technology for taking a surface self-wrinkled texture pattern based on cholesteric liquid crystal core-shell liquid drops as an artificial fingerprint information anti-counterfeiting mark. The artificial fingerprint is formed by a micro-nano three-dimensional microstructure, and the fingerprint feature of each liquid drop has high randomness and unpredictability, so that the artificial fingerprint cannot be cloned and copied, and has high safety. The artificial fingerprint texture on the surface of the liquid drop has detail features (such as end points, bifurcation points, streaks and the like) and overall features (such as bow-shaped grains, annular grains, spiral grains and the like) similar to human fingerprints, and meanwhile, the information density is higher. And verification can be carried out on the basis of existing commercial fingerprint optical identification hardware equipment, so that the application cost is reduced, and the identification accuracy is ensured. Based on different safety application scenes, the liquid crystal liquid drops with the artificial fingerprints can be solidified into particles, the particles are loaded into various materials or objects to serve as identification devices, integration is easy, and wide application prospects are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of anti-counterfeiting materials, and in particular relates to a marker based on self-wrinkle texture on the surface of a liquid crystal droplet, a generation method thereof, and an anti-counterfeiting material. Background Art

[0002] Wrinkled textures 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 have specific functionalities, such as increasing surface area, improving grip, hydrophobicity, defense, and optical effects. Fingerprints are wrinkled texture patterns unique to the epidermis of human fingers. As a biological feature, they are highly unique and stable, and are therefore widely used in the fields of information anti-counterfeiting and identity authentication. Inspired by this, the development of anti-counterfeiting identification devices based on wrinkled textures as artificial fingerprints has important application value.

[0003] Human fingerprints are highly unique and lifelong, and are widely used in anti-counterfeiting, encryption, identity authentication and other fields. However, with the advancement of imitation technologies such as high-precision silicone molds, the risk of fingerprints being copied and forged has increased significantly. At the same time, once fingerprint information is leaked, it will pose a long-term threat to the privacy and security of users due to its immutability. In order to meet these challenges, the development of anti-counterfeiting identification devices based on wrinkle textures as artificial fingerprints has gradually emerged. This emerging anti-counterfeiting technology can effectively solve the risk of biological data leakage while maintaining high security. This type of technology uses some technical methods to form a random and unique wrinkle texture pattern on the surface of the material as an anti-counterfeiting mark. Although some advanced technologies can generate artificial fingerprint textures with randomness and certain characteristics (unique and recognizable), this type of artificial texture generally has problems such as low information density (less complex details than human fingerprints), difficulty in preparation, high cost, and difficulty in ensuring recognition accuracy. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a marker based on the self-wrinkle texture on the surface of a liquid crystal droplet, a generation method, and an anti-counterfeiting material.

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

[0006] The present invention provides a method for generating a marker based on the self-wrinkle texture on the surface of a liquid crystal droplet, comprising:

[0007] Obtaining a mixed solution having at least one liquid crystal droplet; 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 a droplet as a shell and at least one droplet located in the shell and serving as a core, and a cholesteric liquid crystal mixed solution is present between the shell and the core;

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

[0009] The at least one liquid crystal droplet after the texture feature is changed or the mixed solution of the at least one liquid crystal droplet after the texture feature is changed is subjected to an in-situ curing processing to obtain a marker based on the self-wrinkle texture of the liquid crystal droplet surface and having at least one liquid crystal droplet particle; wherein the texture feature of the identification area of ​​the at least one liquid crystal droplet is used as the identification information of the marker, and the texture features of the identification areas of different liquid crystal droplets are different, and the texture of the identification area of ​​each liquid crystal droplet contains the texture features of a human fingerprint.

[0010] The present invention also provides a marker based on the self-wrinkle texture on the surface of a liquid crystal droplet, the marker comprising: at least one liquid crystal droplet particle, the at least one liquid crystal droplet particle is obtained by in-situ curing processing of at least one liquid crystal droplet suspended in a mixed solution and having changed texture features, the central area of ​​the lower surface along the gravity direction of each liquid crystal droplet after the texture features are changed is the identification area of ​​the liquid crystal droplet; the texture features of the identification area of ​​each liquid crystal droplet after the texture features are changed are obtained by adjusting the property information and / or the lighting method of the liquid crystal droplet, wherein the texture features of the identification area of ​​the at least one liquid crystal droplet serve as the anti-counterfeiting identification information of the marker, and the texture features of the identification areas of different liquid crystal droplets are different, and the texture of the identification area of ​​each liquid crystal droplet includes the texture features of human fingerprints.

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

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention changes the texture characteristics of the self-wrinkling stripes on the surface of the liquid crystal droplet by adjusting the property information and / or the illumination mode of each liquid crystal droplet, so that the texture at the central area of ​​the lower surface of each liquid crystal droplet contains the texture characteristics of human fingerprints, thereby producing an artificial texture similar to a human fingerprint on the droplet surface, so that the artificial texture has detail features (such as endpoints, bifurcation points, lines, etc.) and overall features (such as arch patterns, ring patterns, spiral patterns, etc.) similar to human fingerprints, thereby making the artificial texture more complex, and making the human fingerprint recognition method applicable to the artificial texture recognition method, and can be verified based on existing commercial fingerprint optical recognition hardware equipment, which not only improves the information density of the artificial texture, but also improves the recognition accuracy of the artificial texture; and, because only the property information and / or illumination mode of the liquid crystal droplet are adjusted when preparing the artificial texture, the materials involved have been commercially used on a large scale in the information display industry, and thus the preparation difficulty is low and the cost is low. In addition, the artificial texture features produced on the surface of the droplet of the present invention are highly random and unpredictable, that is, they are both random and characteristic, and therefore cannot be cloned or copied, and have a high degree of security. In addition, the artificial texture features produced on the surface of the droplet of the present invention vary according to the intensity of the adjustment of the attribute information of the liquid crystal droplet and / or the illumination mode, so that artificial textures with rich and diverse texture patterns can be produced by the present invention. In addition, the present invention obtains a marker by in-situ solidification of the droplet, so that the marker can be encapsulated in various materials, and has broad application prospects in the fields of anti-counterfeiting, encryption and identification.

[0014] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a flow chart of a method for generating a marker based on the self-wrinkle texture on the surface of a liquid crystal droplet provided by an embodiment of the present invention;

[0016] Figure 2 It is a side view structural principle diagram, a real side view and a real top view of a liquid crystal droplet with a core-shell sphere structure provided by an embodiment of the present invention;

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

[0018] Figure 4 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 by an embodiment of the present invention;

[0019] Figure 5It is a schematic diagram of micro texture patterns on the lower surface of different liquid crystal droplets with an overall size of 200 microns and a cholesteric chiral dopant weight ratio of 1%, 2%, and 3% in the cholesteric liquid crystal mixed solution in the shell provided by an embodiment of the present invention;

[0020] Figure 6 It is a schematic diagram of microscopic texture patterns on the lower surface of a liquid crystal droplet at different irradiation stages when a plurality of liquid crystal droplets of the same size are uniformly irradiated by an intermittent irradiation method including a plurality of irradiation cycles provided by an embodiment of the present invention;

[0021] Figure 7 is a schematic diagram of the texture patterns on the lower surfaces of eight different liquid crystal droplets provided by an embodiment of the present invention when they are in a steady state (or a transient steady state);

[0022] Figure 8 is a schematic diagram of texture patterns of six different liquid crystal droplets on the bottom surface of which the texture patterns are solidified at a certain moment during the evolution process provided by an embodiment of the present invention;

[0023] Fig. 9 It is a front schematic diagram of a film obtained by in-situ curing and other treatments of a mixed solution and a large number of liquid crystal droplets with changed texture characteristics suspended in the mixed solution, provided by an exemplary embodiment of the present invention;

[0024] Fig.10 It is a statistical graph of ridge density data of 300 artificial fingerprint images provided by an embodiment of the present invention;

[0025] Fig.11 It is a statistical graph of artificial fingerprint unclonability (Hamming distance) data of 300 artificial fingerprint images provided by an embodiment of the present invention. DETAILED DESCRIPTION

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

[0027] Figure 1 is a flow chart of a method for generating a marker based on a self-wrinkle texture on the surface of a liquid crystal droplet provided by an embodiment of the present invention, such as Figure 1 As shown, the method includes:

[0028] S101. Obtain a mixed solution having at least one liquid crystal droplet; 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 includes a droplet as a shell and at least one droplet located in the shell and serving as a core, and a cholesteric liquid crystal mixed solution is present between the shell and the core.

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

[0030] For example, Figure 2 It is a side view structural principle diagram, real side view and real top view of a liquid crystal droplet with a core-shell sphere structure, and, Figure 2 The liquid crystal droplet shown includes a core body. Figure 2 In the figure, (a) is a side view of a liquid crystal droplet with a core-shell sphere structure, (b) is a real side view of a liquid crystal droplet with the core-shell sphere structure of (a), and (c) is a real top view of a liquid crystal droplet with the core-shell sphere structure of (a). Figure 2 Here, 1 represents the droplet core (i.e., the core of the liquid crystal droplet), 2 represents the droplet shell (i.e., the shell of the liquid crystal droplet), 3 represents the mixed solution around 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 liquid crystal mixed solution contains: liquid crystal, cholesteric chiral dopant, ultraviolet light curing material and photoinitiator. For example, the liquid crystal can be E7 liquid crystal, the type of cholesteric chiral dopant can be R811, the type of photoinitiator can be Irgacure 651, and the type of ultraviolet light curing material can be RM257. The weight ratio of each component can be set according to actual needs. For example, the weight ratio of cholesteric chiral dopant, ultraviolet light curing material and photoinitiator ranges from 0.1% to 20%, 1% to 25% and 0.1% to 10%, respectively. Exemplarily, the weight ratio of cholesteric chiral dopant, ultraviolet light curing material and photoinitiator can be 3%, 15% and 5%, respectively.

[0032] Here, the mixed solution in which the liquid crystal droplets are located can be a sodium dodecyl sulfate (SDS) aqueous solution, and the weight ratio of the sodium dodecyl sulfate aqueous solution can range from 0.1% to 20%. Exemplarily, the mixed solution in which the liquid crystal droplets are located can be a sodium dodecyl sulfate aqueous solution with a weight ratio of 2%.

[0033] Here, the droplet core also contains a solution, for example, a polyvinyl alcohol aqueous solution, the weight ratio of which can range from 0.5% to 80%. Exemplarily, the solution in the droplet core can be a polyvinyl alcohol (PVA) aqueous solution 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 the at least one liquid crystal droplet may be the same or different, and the present invention is not limited to this.

[0036] S102. Change the texture characteristics of the central area of ​​the lower surface of each liquid crystal droplet along the gravity direction by adjusting the property information and / or lighting method of each liquid crystal droplet; wherein the central area of ​​the lower surface of each liquid crystal droplet is the identification area of ​​the liquid crystal droplet.

[0037] S103. Perform in-situ curing processing on at least one liquid crystal droplet after the texture feature is changed or a mixed solution of at least one liquid crystal droplet after the texture feature is changed, so as to obtain a marker based on the self-wrinkle texture of the liquid crystal droplet surface and having at least one liquid crystal droplet particle; wherein the texture feature of the identification area of ​​at least one liquid crystal droplet serves as the anti-counterfeiting identification information of the marker, and the texture features of the identification areas of different liquid crystal droplets are different, and the texture of the identification area of ​​each liquid crystal droplet contains the texture features of human fingerprints.

[0038] Here, the texture of the identification area of ​​each liquid crystal droplet contains texture features similar to those of a human fingerprint, that is, it has detail features and overall features similar to those of a human fingerprint.

[0039] In the present invention, the liquid crystal droplets are stably suspended in the mixed solution, and the mixed solution in which the liquid crystal droplets are suspended and the aqueous solution in the droplet core are doped with surfactants to play two roles: one is to reduce the interfacial tension to maintain the stability of the liquid crystal droplet structure, and the other is to provide specific anchoring conditions and anchoring strength for the liquid crystal in the liquid crystal droplet shell. The anchoring conditions include horizontal anchoring conditions and vertical anchoring conditions, which make the liquid crystal molecules tend to be arranged parallel or perpendicular to the liquid interface; wherein the anchoring strength determines the degree to which the liquid crystal molecules are arranged 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 have horizontal or vertical anchoring conditions respectively, and 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, and the mixed anchoring conditions are typical anchoring conditions of the liquid crystal droplets in the present invention.

[0040] The inventors of the present invention have discovered that within the shell of the above-mentioned liquid crystal droplet, the arrangement of the liquid crystal molecules is subject to the combined influence of multiple factors such as the geometric constraints of the inner and outer spherical interfaces, anchoring conditions and anchoring strength, interfacial tension, shell thickness, and the elastic force between liquid crystal molecules in the cholesteric phase liquid crystal, and helical twisting force. Under the combined effect of these factors, the liquid crystal molecules in the droplet shell adjust their own arrangement so that the total energy of the liquid crystal droplet system tends to a low energy state, thereby promoting the transition of the liquid crystal droplet system from an unsteady state to a steady state (or a temporary steady state). Based on the arrangement of the liquid crystal molecules in the shell of the liquid crystal droplet, an undulating wrinkled stripe texture can be spontaneously formed 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 respectively called the upper surface and the lower surface. In particular, the lower interface of the liquid crystal droplet has a rich wrinkled stripe texture pattern, showing obvious regularity and characteristic features. Exemplary, Figure 3 Figure (a) shows a typical microscopic texture of the upper surface of a core-shell sphere structured liquid crystal droplet, Figure (b) shows a typical microscopic texture of the side surface of the core-shell sphere structured liquid crystal droplet, and Figure (c) shows a typical microscopic texture of the lower surface of the core-shell sphere structured liquid crystal droplet. Figure 3 As shown, the edge areas of the texture pattern at the upper and lower surfaces are concentric circular wrinkle stripes, and the side surface has parallel circular wrinkle stripes. It can be observed that the above concentric circular wrinkle stripes extend from the top edge of the droplet to the bottom edge. The texture pattern in the central area of ​​the lower surface of the liquid crystal droplet has a high degree of randomness. Therefore, the texture pattern in the central area of ​​the lower surface of the liquid crystal droplet can be used as the identification area of ​​the generated marker. In addition, the process of spontaneous minimization of the energy of the above liquid crystal droplet system, or the process of changing the arrangement of liquid crystal molecules by external means, can be manifested as the dynamic evolution of the wrinkle texture on the surface of the droplet on a macroscopic scale. Based on this, the present invention adopts the above S102 to change the texture characteristics of the self-wrinkle stripes on the surface of the liquid crystal droplet, so as to realize the regulation of the texture characteristics of the self-wrinkle stripes on the lower surface of the liquid crystal droplet, and then generate a marker based on the self-wrinkle texture of the liquid crystal droplet surface.

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

[0042] S1021. Increase the area of ​​the identification region of each liquid crystal droplet by adjusting the first attribute information of the liquid crystal droplet; wherein, when the area of ​​the identification region increases, the information capacity of the identification region increases.

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

[0044] Specifically, the first attribute information may be the size of the nucleus of each liquid crystal droplet, the number of nuclei of each liquid crystal droplet, or 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-wrinkle stripe pattern on the surface of the liquid crystal droplet that can be used as the identification area of ​​the liquid crystal droplet increases, that is, the area of ​​the texture pattern at the center area of ​​the lower surface of the liquid crystal droplet increases.

[0045] For example, Figure 4 It is a schematic diagram of different liquid crystal droplets with an overall size of 200 microns and core sizes of 168.8 microns, 188.1 microns, and 194.5 microns, respectively. In addition, the material components of the cholesteric liquid crystal mixed solution between the shell and the core of the liquid crystal droplet are: E7, 3% by weight R811, 15% by weight RM257, and 5% by weight Irgacure651; the droplet core contains 1% by weight PVA aqueous solution, and the mixed solution in which the liquid crystal droplet is located is 2% by weight SDS aqueous solution.

[0046] Specifically, in Figure 4 In the figure, the upper figure in (a) is a side view of a liquid crystal droplet with a core size of 168.8 microns, and area 11 in the lower figure in (a) is a microscopic texture pattern at the center area of ​​the lower surface of the liquid crystal droplet with a core size of 168.8 microns; the upper figure in (b) is a side view of a liquid crystal droplet with a core size of 188.1 microns, and area 13 in the lower figure in (b) is a microscopic texture pattern at the center area of ​​the lower surface of the liquid crystal droplet with a core size of 188.1 microns; the upper figure in (c) is a side view of a liquid crystal droplet with a core size of 194.5 microns, and area 15 in the lower figure in (c) is a microscopic texture pattern at the center area of ​​the lower surface of the liquid crystal droplet with a core size of 194.5 microns. Affected by the density difference between the droplet core and the material in the shell, the droplet core is in close contact with the inner wall of the upper interface of the liquid crystal droplet, and the lower interface of the liquid crystal droplet, that is, the interface downward along the gravity direction, is the characteristic recognition area (marking area) of the liquid crystal droplet. Obviously, by increasing the size of the droplet core in the liquid crystal droplet, the area of ​​the texture image at the central area 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 S102 may be implemented as step S1022:

[0048] S1022. Increase the texture richness of the identification area of ​​each liquid crystal droplet by adjusting the second attribute information of the liquid crystal droplet; wherein, when the texture richness of the identification area increases, the information density per unit area of ​​the identification 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, or the helical twisting force of the cholesteric chiral dopant, or the enantiomeric excess value of the cholesteric chiral dopant, or any combination of these three parameters, wherein different types of cholesteric chiral dopants have different helical twisting forces.

[0051] Exemplarily, when the texture richness of the marking area of ​​the liquid crystal droplet is increased 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 the cholesteric liquid crystal mixed solution is 15%.

[0052] For example, Figure 5 The figure is a schematic diagram of the micro texture pattern of the lower surface of different liquid crystal droplets with an overall size of 200 microns and a cholesteric chiral dopant weight ratio of 1%, 2%, and 3% in the cholesteric liquid crystal mixed solution in the shell, and the components of other materials in the cholesteric liquid crystal mixed solution are: E7, 15% by weight of RM257, 5% by weight of Irgacure 651; the droplet core is a 1% by weight PVA aqueous solution, and the mixed solution where the liquid crystal droplet is located is a 2% by weight SDS aqueous solution. Specifically, in Figure 5 In the figure, region 17 in (a) is the texture pattern of the central region of the lower surface of a liquid crystal droplet with a cholesteric chiral dopant weight ratio of 1%, region 18 in (b) is the texture pattern of the central region of the lower surface of a liquid crystal droplet with a cholesteric chiral dopant weight ratio of 2%, and region 19 in (c) is the texture pattern of the central region of the lower surface of a liquid crystal droplet with a cholesteric chiral dopant weight ratio of 3%. By comparison, it is found that although a wrinkle texture pattern is randomly formed in the central region of the lower surface of the above three droplets, it can be clearly observed that with the increase of the doping concentration of the cholesteric chiral agent, the interval width of the wrinkle stripes from 17, 18 to 19 becomes narrower, and the details of the texture pattern are more numerous and more complex. The change in the concentration of the cholesteric chiral dopant essentially changes the pitch formed by the helical twisted arrangement between the liquid crystal molecules, thereby achieving the regulation of the texture characteristics of the texture pattern in the central region of the lower surface of the liquid crystal droplet.

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

[0054] S1023. Increase the complexity of the overall texture pattern of the marking area of ​​the liquid crystal droplet by adjusting the lighting process method (light intensity, frequency, total energy) of each liquid crystal droplet.

[0055] Specifically, by making the illumination mode of each liquid crystal droplet an intermittent illumination mode including multiple illumination cycles, the number of arch patterns in the marking area of ​​the liquid crystal droplet is reduced, and at the same time, the number of ring patterns and spiral patterns is generated and increased; wherein the ring patterns and spiral patterns are evolved from the arch patterns; wherein each illumination cycle consists of illumination time and pause time.

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

[0057] In some embodiments, when the material system of the liquid crystal droplet belongs to the first preset material system, that is, when the type of liquid crystal in the cholesteric liquid crystal mixed solution of the liquid crystal droplet belongs to the first preset liquid crystal type, and the type of cholesteric chiral dopant in the cholesteric liquid crystal mixed solution of the liquid crystal droplet belongs to the first preset dopant type, the number of repetitions of the irradiation cycle is negatively correlated with the number of arched lines in the identification area of ​​the liquid crystal droplet, and positively correlated with the number of ring lines and spiral lines in the identification area of ​​the liquid crystal droplet. Both the illumination intensity and the illumination frequency are positively correlated with the evolution speed of the arched lines to ring lines or spiral lines.

[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 mixed solution of the liquid crystal droplet belongs to the second preset liquid crystal type, and the type of cholesteric chiral dopant in the cholesteric liquid crystal mixed solution of the liquid crystal droplet belongs to the second preset dopant type, the number of repetitions of the irradiation cycle is positively correlated with the number of arch patterns in the identification area of ​​the liquid crystal droplet, and negatively correlated with the number of ring patterns and spiral patterns in the identification area 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. Exemplarily, when the liquid crystal in the cholesteric liquid crystal mixed solution of a liquid crystal droplet is E7 liquid crystal, and the cholesteric chiral dopant in the cholesteric liquid crystal mixed solution of the liquid crystal droplet is R811, the number of repetitions of the irradiation cycle is negatively correlated with the number of arched lines in the identification area of ​​the liquid crystal droplet, and positively correlated with the number of annular lines and spiral lines in the identification area of ​​the liquid crystal droplet.

[0060] For example, Figure 6A schematic diagram of the microscopic texture pattern of the lower surface of a liquid crystal droplet at different irradiation stages when a plurality of liquid crystal droplets of the same size are uniformly irradiated by an intermittent irradiation method including multiple irradiation cycles, and the overall size of the liquid crystal droplets is 200 microns, the weight ratio of R811 in the cholesteric liquid crystal mixed solution in the shell is 3%, and the components of other materials in the cholesteric liquid crystal mixed solution are: E7, 15% by weight of RM257, 5% by weight of Irgacure 651; the droplet core is a 1% by weight PVA aqueous solution, and the mixed solution in which the liquid crystal droplets are located is a 2% by weight SDS aqueous solution. The intermittent irradiation method includes a first irradiation cycle, a second irradiation cycle, and a third irradiation cycle, a total of 3 irradiation cycles, and the number of cycles of each irradiation cycle is 3 times; in the first irradiation cycle, the ultraviolet irradiation is 0.5 minutes and paused for 1 minute, in the second irradiation cycle, the ultraviolet irradiation is 5 minutes and paused for 5 minutes, and in the third irradiation cycle, the ultraviolet irradiation is 0.5 minutes and paused for 10 minutes.

[0061] Specifically, in Figure 6 In the figure, (a) shows the microtexture pattern on the lower surface of multiple liquid crystal droplets of the same size that have not been exposed to ultraviolet light, (b) shows the microtexture pattern on the lower surface of multiple liquid crystal droplets of the same size that have undergone the first illumination cycle, (c) shows the microtexture pattern on the lower surface of multiple liquid crystal droplets of the same size that have undergone the first and second illumination cycles, and (d) shows the microtexture pattern on the lower surface 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 at the center area of ​​the lower surface of the liquid crystal droplet solidifies, and the shell of the liquid crystal droplet changes from liquid to solid. Figure 6 As shown in the figure, during the ultraviolet light treatment, the texture pattern at the center area of ​​the lower surface of the liquid crystal droplet undergoes a dynamic evolution. Specifically, the texture pattern at the center area of ​​the lower surface of the liquid crystal droplet treated with the first, second, and third light cycles rotates continuously in a clockwise spiral, which is consistent with the chirality of the cholesteric chiral dopant in the shell of the liquid crystal droplet (R811 is a right-handed cholesteric chiral dopant). Because the texture pattern has similar overall characteristics to human fingerprints, based on the classification method of the primary features of human fingerprints (arch patterns, ring patterns, spiral patterns), it can be concluded that the texture features after ultraviolet light treatment change from being dominated by arch patterns to being dominated by ring patterns and spiral patterns. The evolution of the arch patterns in the texture pattern into ring patterns or spiral patterns can be called the evolution of the texture pattern.

[0062] Here, by adjusting the light intensity and / or light frequency, the speed at which the texture pattern on the lower surface of the liquid crystal droplet evolves can be changed. At the same time, when the total light energy meets the requirements of the material system of the liquid crystal droplet, the texture pattern on the lower surface of the liquid crystal droplet can be solidified to form a solidified texture. For example, Figure 7 and Figure 8 The following are typical texture patterns on the bottom surface of different liquid crystal droplets that have been cured. Figure 6 The dynamic evolution of the texture of the same group of liquid crystal droplets is shown in Figure 2. Figure 7 and Figure 8 The liquid crystal droplets are in different stages of evolution, and the texture patterns below have different types of characteristic information. The essence of the liquid crystal droplet texture evolution is the dynamic evolution of the arrangement order of liquid crystal molecules in the liquid crystal droplet. From the perspective of the energy of the liquid crystal droplet system, this process can be divided into transient, temporary steady state and steady state. Figure 7 It is a schematic diagram of the texture patterns on the lower surfaces of eight different liquid crystal droplets when they are in a steady state (or a transient steady state). Figure 8 Schematic diagram of the texture patterns of the lower surfaces of six different liquid crystal droplets being solidified at a certain moment in the evolution process, when the liquid crystal droplets are in a transient state (or transient state). Figure 8 This is a schematic diagram of the texture patterns on the bottom surface of six different liquid crystal droplets in an unstable state. Figure 7 and Figure 8 It can be found that when the liquid crystal molecules in the liquid crystal droplet shell are arranged in a steady state (or temporary steady state) so that the system energy reaches a minimum or a minimum value, the texture features of the texture pattern in the central area of ​​the lower surface of the liquid crystal droplet after the liquid crystal droplet solidifies are richer in details and more regular.

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

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

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

[0066] The liquid crystal droplets with the above-mentioned texture features changed have different texture patterns in the center area of ​​the lower surface of each droplet, even if they are from the same batch of liquid crystal droplets processed under the same process conditions (having the same core-shell size, number of cores, material composition, etc.), and have a physically unclonable feature (PUF), which can be used as an artificial fingerprint marker. Based on the needs of actual application scenarios, the liquid crystal droplet shell, droplet core, and solution containing the droplet can be solidified separately and loaded into various packaging forms as anti-counterfeiting marks.

[0067] In some embodiments, for the above S103, after step S102, when at least one liquid crystal droplet with changed texture features in the mixed solution has been solidified in situ, the mixed solution can be further solidified by irradiation with light to solidify the mixed solution and the liquid crystal droplets with changed texture features into a whole, and then the whole is subjected to other processing to obtain a marker, or the whole is directly used as a marker.

[0068] The in-situ curing method can be used to in-situ cure the arrangement of the liquid crystal molecules in the shell of the liquid crystal droplet at a specific moment, and then a long-term stable artificial fingerprint pattern can be obtained in the central area of ​​the lower surface of the liquid crystal droplet, which can be used as the characteristic recognition area of ​​the liquid crystal droplet. After in-situ curing, the liquid crystal droplet is easy to integrate and can be packaged in various forms, which has broad application prospects in the fields of anti-counterfeiting, encryption and identification.

[0069] In some embodiments, for the above S103, after step S102, when the liquid crystal droplets after at least one texture feature in the mixed solution has been solidified in situ, the obtained liquid crystal droplet solidified particles can continue to be processed by other methods to obtain a marker, or the obtained liquid crystal droplet solidified particles can be directly used as a marker.

[0070] In some embodiments, for the above S103, after step S102, if at least one of the liquid crystal droplets in the mixed solution with changed texture features has not solidified, the mixed solution and the liquid crystal droplets can also be solidified in situ by irradiation with light, so as to solidify the mixed solution and the liquid crystal droplets with changed texture features into a whole, and then perform other processing on the whole to obtain a marker, or directly use the whole as a marker.

[0071] In some embodiments, for the above S103, after step S102, if the liquid crystal droplets after at least one texture feature in the mixed solution is changed have not solidified, the liquid crystal droplets can be solidified in situ, and then the obtained liquid crystal droplet solidified particles can be further processed to obtain a marker, or the obtained liquid crystal droplet solidified particles can be directly used as a marker.

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

[0073] For example, Fig. 9It is a front schematic diagram of a film obtained after in-situ curing and other treatments of a mixed solution and a large number of liquid crystal droplets with changed texture characteristics suspended in the mixed solution, and the front of the film is the side where the lower surfaces of all the liquid crystal droplets along the direction of gravity are located. Fig. 9 The size of the liquid crystal droplets shown is 100 microns, the weight ratio of R811 in the cholesteric liquid crystal mixed solution in the shell is 3%, and the components of other materials in the cholesteric liquid crystal mixed solution are: E7, 15% by weight of RM257, 5% by weight of Irgacure 651; the droplet core is a 1% by weight PVA aqueous solution, and the mixed solution where the liquid crystal droplets are located is a 2% by weight SDS aqueous solution. The curing process is: after being treated with 365nm ultraviolet light (light intensity 420mW±5μW) for 6 minutes, it is cured into particles with a stable texture pattern, and the batch of liquid crystal droplet solidified particles is added to the PDMS mixture (polydimethylsiloxane), and allowed to stand for 30 minutes. Then, the PDMS mixture with the liquid crystal droplet solidified particles is placed in a vacuum oven at 50 degrees Celsius for 3 hours to obtain a polymer film, which contains a large number of liquid crystal droplet solidified particles, and the lower surface of the liquid crystal droplet solidified particles faces the same direction, which is the front side of the film.

[0074] The present invention also provides a marker based on the self-wrinkle texture on the surface of a liquid crystal droplet, the marker is generated by the above-mentioned method for generating a marker based on the self-wrinkle texture on the surface of a liquid crystal droplet, and the marker comprises: at least one liquid crystal droplet particle, the at least one liquid crystal droplet particle is obtained by in-situ curing processing of at least one liquid crystal droplet suspended in a mixed solution and having changed texture features, the center area of ​​the lower surface along the gravity direction of each liquid crystal droplet after the texture features have changed is the identification area of ​​the liquid crystal droplet; the texture features of each liquid crystal droplet after the texture features have changed are obtained by adjusting the property information and / or the lighting method of the liquid crystal droplet, wherein the texture features of the identification area of ​​at least one liquid crystal droplet are used as the anti-counterfeiting identification information of the marker, and the texture features of the identification areas of different liquid crystal droplets are different, and the texture of the identification area of ​​each liquid crystal droplet contains the texture features of a human fingerprint. Exemplarily, the marker can be Fig. 9 The film shown, or Fig. 9 The liquid crystal droplets shown are solidified particles.

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

[0076] The present invention also provides an anti-counterfeiting material, which comprises: the above-mentioned marker based on the self-wrinkle texture on the surface of the liquid crystal droplet, and a material used as a carrier of the marker.

[0077] Exemplarily, the anti-counterfeiting material may be a spray, coating, ink, film, fiber, adhesive, tape, etc. carrying a marker. As long as the material carries the marker of the present invention, it belongs to the anti-counterfeiting material described in the present invention.

[0078] In order to verify the characteristics of the artificial fingerprint (i.e., the texture at the center area of ​​the lower surface) of the liquid crystal droplet of the present invention, the present invention conducts the following experiments:

[0079] Experiment 1: From Fig. 9 The artificial fingerprints of different liquid crystal particles in the polymer film shown in the figure are taken by microscopic texture images, and the artificial fingerprint database of liquid crystal particles is established. The sample capacity of liquid crystal particles in the database is 300. Because the artificial fingerprint has similar overall characteristics to human fingerprints, based on the classification method of human fingerprint secondary features (fingerprint detail points, such as intersections and endpoints), the texture patterns in the artificial fingerprint database are processed and analyzed by image processing, and the secondary feature detail endpoints are extracted. It can be concluded that the average ridge density in the 300 artificial fingerprint images is 5.8×10 5 (Details per 25 square millimeters), as follows Fig.10 As shown. In comparison, the ridge density of human fingerprints is about 30 to 80 (minutiae points per 25 square millimeters). In contrast, the detail density (information density) of the artificial fingerprint of the liquid crystal droplets in the present invention is 4 orders of magnitude higher than that of human fingerprints. The data on the ridge density of human fingerprints comes from the record of "Naser Zaeri, Minutiae-based Fingerprint Extraction and Recognition, Biometrics, 2011".

[0080] Experiment 2: The hash algorithm is used to calculate the Hamming distance between the 300 images in the artificial fingerprint database. The Hamming distance is used to measure the similarity between two images. The Hamming distance ranges from 0 to 1. When the value is greater than the threshold of 0.75, it means that the two images are similar, and when it is lower than the threshold of 0.75, it means that the two images are not similar. Fig.11 As shown in the Hamming distance grayscale image, the similarities of the 300 images in the above database are all below the threshold, which proves that the artificial fingerprints of all liquid crystal particles in the above database are unique.

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

[0082] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0083] In the specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality of components. Certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good effects.

[0084] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for generating a marker based on the self-wrinkle texture of a liquid crystal droplet surface, characterized in that: include: obtaining a mixed solution having at least one liquid crystal droplet; 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 includes a droplet as a shell and at least one droplet located in the shell and serving as a core, and a cholesteric liquid crystal mixed solution is provided between the shell and the core; By adjusting the property information and / or the illumination mode of each liquid crystal droplet, the texture characteristics of the central area of ​​the lower surface of the liquid crystal droplet along the gravity direction are changed; wherein the central area of ​​the lower surface of each liquid crystal droplet is the identification area of ​​the liquid crystal droplet; The at least one liquid crystal droplet after the texture feature is changed or the mixed solution of the at least one liquid crystal droplet after the texture feature is changed is subjected to an in-situ curing processing to obtain a marker based on the self-wrinkle texture of the liquid crystal droplet surface and having at least one liquid crystal droplet particle; wherein the texture feature of the identification area of ​​the at least one liquid crystal droplet serves as the anti-counterfeiting identification information of the marker, and the texture features of the identification areas of different liquid crystal droplets are different, and the texture of the identification area of ​​each liquid crystal droplet contains the texture features of human fingerprints.

2. The method for generating a marker based on the self-wrinkle texture of a liquid crystal droplet surface according to claim 1, characterized in that: The method of changing the texture characteristics of the central area of ​​the lower surface of each liquid crystal droplet along the gravity direction by adjusting the property information and / or the illumination mode of each liquid crystal droplet comprises at least one of the following adjustment steps: A first property adjustment step: increasing the area of ​​the identification region of the liquid crystal droplet by adjusting the first property information of each liquid crystal droplet; wherein, when the area of ​​the identification region increases, the information capacity of the identification region increases; A second property adjustment step: increasing the texture richness of the identification area of ​​the liquid crystal droplet by adjusting the second property information of each liquid crystal droplet; wherein, when the texture richness of the identification area increases, the information density per unit area of ​​the identification area increases; Lighting method adjustment step: by adjusting the lighting 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 increases, the type of characteristic information of the texture pattern of the identification area increases.

3. The method for generating a marker based on the self-wrinkle texture of a liquid crystal droplet surface according to claim 2, characterized in that: The step of increasing the area of ​​the identification region of each liquid crystal droplet by adjusting the first property information of each liquid crystal droplet comprises: By increasing the first property information of each liquid crystal droplet, the area of ​​the identification region of the liquid crystal droplet is increased.

4. The method for generating a marker based on the self-wrinkle texture of a liquid crystal droplet surface according to claim 2 or 3, characterized in that: The first attribute information includes at least one of the following attribute information: the size of the core body and the number of the core bodies.

5. The method for generating a marker based on the self-wrinkle texture of a liquid crystal droplet surface according to claim 2, characterized in that: The step of increasing the texture richness of the marked area of ​​the liquid crystal droplet by adjusting the second property information of each liquid crystal droplet comprises: By increasing the second property information of each liquid crystal droplet, the texture richness of the identification area of ​​the liquid crystal droplet is increased.

6. The method for generating a marker based on the self-wrinkle texture of a liquid crystal droplet surface according to claim 2 or 5, characterized in that: The second attribute information includes at least one of the following attribute information: The doping concentration of the cholesteric chiral dopant in the cholesteric liquid crystal mixed solution, the enantiomeric excess value of the cholesteric chiral dopant, and the helical twisting force of the cholesteric chiral dopant; wherein different types of cholesteric chiral dopants have different helical twisting forces.

7. The method for generating a marker based on the self-wrinkle texture of a liquid crystal droplet surface according to claim 2, characterized in that: The method of adjusting the illumination process of each liquid crystal droplet to increase the complexity of the overall texture pattern of the identification area of ​​the liquid crystal droplet includes: By making the illumination mode of each liquid crystal droplet an intermittent illumination mode including a plurality of illumination cycles, the number of arch patterns in the marking area of ​​the liquid crystal droplet is reduced, and the number of ring patterns and spiral patterns is generated and increased; wherein the ring patterns and the spiral patterns are evolved from the arch patterns; wherein each illumination cycle can be repeated, and each illumination cycle consists of an illumination time and a pause time.

8. The method for generating a marker based on the self-wrinkle texture of a liquid crystal droplet surface according to claim 7, characterized in that: The cholesteric liquid crystal mixed solution contains liquid crystal and cholesteric chiral dopant; when the type of the liquid crystal belongs to the first preset liquid crystal type, and the type of the cholesteric chiral dopant belongs to the first preset dopant type, the number of repetitions of the irradiation cycle is negatively correlated with the number of the arch patterns in the identification area of ​​the liquid crystal droplet, and positively correlated with the number of the ring patterns and the spiral patterns in the identification area of ​​the liquid crystal droplet, and the illumination intensity and illumination frequency are both positively correlated with the evolution speed of the arch patterns to the ring patterns or the spiral patterns.

9. A marker based on the self-wrinkling texture of a liquid crystal droplet surface, characterized in that: The marker comprises: at least one liquid crystal droplet particle, wherein the at least one liquid crystal droplet particle is obtained by in-situ curing processing of at least one liquid crystal droplet suspended in a mixed solution and having changed texture features, wherein the central area of ​​the lower surface along the gravity direction of each liquid crystal droplet after the texture features are changed is the identification area of ​​the liquid crystal droplet; the texture features of the identification area of ​​each liquid crystal droplet after the texture features are changed are obtained by adjusting the property information and / or the lighting method of the liquid crystal droplet, wherein the texture features of the identification area of ​​the at least one liquid crystal droplet serve as the anti-counterfeiting identification information of the marker, and the texture features of the identification areas of different liquid crystal droplets are different, and the texture of the identification area of ​​each liquid crystal droplet includes the texture features of human fingerprints.

10. An anti-counterfeiting material, characterized in that: It comprises: a marker based on the self-wrinkle texture on the surface of a liquid crystal droplet as claimed in claim 9 and a material used as a carrier of the marker.

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