Physical unclonable anti-counterfeiting structure based on bionic nanostructure and application

Abstract

The invention relates to the technical field of anti-counterfeiting, in particular to a physical unclonable anti-counterfeiting structure based on a bionic nanostructure and application. Comprising a substrate; a bionic nanostructure layer is arranged on the substrate; the bionic nanostructure layer comprises an anisotropic sheet-shaped nanostructure and an isotropic columnar nanostructure, and the anisotropic sheet-shaped nanostructure and the isotropic columnar nanostructure are arranged on the same plane in a random multi-mode mode. According to the anti-counterfeiting structure, the problems that a traditional anti-counterfeiting technology is single in feature and easy to copy are solved through a collaborative system of an anisotropic sheet-shaped nano structure and an isotropic columnar nano structure.

Description

Technical Field

[0001] The present invention relates to the field of anti-counterfeiting technology, and particularly to a physically unclonable anti-counterfeiting structure based on a bionic nanostructure and its applications. Background Art

[0002] With the development of the commodity economy, anti-counterfeiting technology has become an important means to protect brand value and consumer rights. Although traditional anti-counterfeiting technologies (such as watermarks, holograms, two-dimensional codes, etc.) are widely used, their anti-counterfeiting features are easily replicated or tampered with by high-precision means, and the security is difficult to meet the requirements of high-end fields. Physically unclonable function (PUF) technology has become a research hotspot in the field of anti-counterfeiting because it generates unique and unpredictable identifiers by using the physical properties of materials, significantly improving the anti-counterfeiting security without the need for additional encrypted storage. However, existing PUF technologies mostly rely on complex lithography and nanoimprinting processing techniques, resulting in high preparation costs, long cycles, and difficulty in compatibility with flexible substrates for some structures (such as silicon-based PUFs), which limits their wide application in fields such as packaging and labels. The preparation cost of existing silicon-based PUF structures is as high as $200 - $500 per square centimeter, and they cannot be bent (the structure breaks when the bending radius > 10 cm), severely limiting their application in the field of flexible packaging. Therefore, there is an urgent need to solve this problem. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a physically unclonable anti-counterfeiting structure based on a bionic nanostructure and its applications. This anti-counterfeiting structure solves the problems of single features and easy replication of traditional anti-counterfeiting technologies through a cooperative system of anisotropic flaky nanostructures and isotropic columnar nanostructures. To achieve the above object, the technical solution of the present invention is realized as follows. A physically unclonable anti-counterfeiting structure based on a bionic nanostructure includes a substrate; a bionic nanostructure layer is provided on the substrate; the bionic nanostructure layer is a combination of anisotropic flaky nanostructures and isotropic columnar nanostructures.

[0004] There are various choices for the arrangement of anisotropic flaky nanostructures and isotropic columnar nanostructures, which can be measured according to actual needs and the simplicity of processing.

[0005] Preferably, the thickness of the bionic nanostructure layer is 120 nm - 320 nm. The periods and heights of the anisotropic flaky nanostructures and isotropic columnar nanostructures can vary to obtain various different effects according to anti-counterfeiting needs.

[0006] Preferably, the substrate is PI or quartz glass, and a flexible PI film as the substrate can be compatible with rigid substrates or flexible substrates.

[0007] Preferably, the anisotropic flaky nanostructures and the isotropic columnar nanostructures are arranged in a random multimodal manner on the same plane.

[0008] Preferably, the random multimodal manner includes one or both of adjusting the arrangement manner and the proportional relationship manner.

[0009] The adjustment of the arrangement manner can be determined by changing the polarization characteristics (i.e., the scanning direction) of the laser: when the laser scans unidirectionally, the anisotropic nanosheet structures are always perpendicular to the laser scanning direction, and the scanning direction of the laser can be changed so that the sheet structures are distributed in different directions.

[0010] Preferably, the material used for the bionic nanostructure layer is polyimide.

[0011] Preferably, the anisotropic flaky nanostructures are formed by unidirectional scanning and peeling of ultraviolet laser along the X-axis of the substrate surface, and the column spacing of the sheet structures in the anisotropic flaky nanostructures is 100 - 240 nm, and the height is 120 - 260 nm.

[0012] For unidirectional scanning, the scanning method is that when scanning, it is necessary to ensure that the spot length can completely cover the circular hole pattern in the mask, and a unified laser energy density and laser irradiation times are adopted. When scanning, ensure that the laser scanning is always in the same direction.

[0013] The anisotropic flaky nanostructures formed by peeling after unidirectional scanning exist on both the quartz glass substrate and the PI film surface, and physical backups can be formed.

[0014] Preferably, the isotropic columnar nanostructures are prepared by bidirectional scanning of ultraviolet laser along the X-axis and Y-axis cross of the substrate surface, and the column diameter range of the isotropic columnar nanostructures is 40 - 45 nm, the height is 160 - 320 nm, and the period (i.e., the center distance between adjacent columns) is 70 - 130 nm.

[0015] For bidirectional scanning, the scanning method is that after the laser scans once in the X-axis or Y-axis direction, the platform controls the sample to rotate 90° for scanning in the other direction, and then rotates back to the original position for scanning. Alternate like this until the PI film completely bulges and separates from the quartz glass substrate.

[0016] The isotropic columnar nanostructures formed by peeling after bidirectional scanning exist on both the quartz glass substrate and the PI film surface, and physical backups can be formed.

[0017] Preferably, the rigid substrate is one of a quartz glass substrate and a silicon wafer, and the flexible substrate is one of PI, PDMS, and PVA.

[0018] Preferably, the anti-counterfeiting structure is applied to item anti-counterfeiting.

[0019] (1) Deposit a layer of metallic Pt on the surface of the anti-counterfeiting structure. The anti-counterfeiting structure will show a blackish transparency, with an obvious light-transmitting effect compared to the non-light-transmitting silver color of the smooth surface. (2) The anti-counterfeiting structure has different reflectivities under the oblique incidence of s-polarized light at 400 nm with an angle of 60°. This result can be measured by a UV-visible spectrophotometer. (3) Backup cross-verification: Observe the surface nanostructure morphology distribution of the anti-counterfeiting structure through a scanning electron microscope, and compare the similarity between the anti-counterfeiting structure and the backup structure.

[0020] The beneficial effects of the present invention are as follows: (1) The anti-counterfeiting structure provided by the present invention has non-clonability: The random morphology of the bionic nanostructure and the synergistic effect of the hybrid structure make it difficult to precisely replicate the anti-counterfeiting features. PUF (Physical unclonable function) is a physical object with inherent, unique, fingerprint-like characteristics, which is defined as non-clonable according to its definition. Its uniqueness is provided by a random pattern based on the random disorder of the microstructure during the manufacturing process of the object. By definition, it is easy to produce and read, but even the manufacturer cannot clone it, nor can it be predicted. Due to the Gaussian distribution of the light intensity of the ultraviolet nanosecond laser, the bionic nanostructure has a random special morphology distribution, and the height and period are random and unpredictable during the preparation process. The nanostructure prepared by the laser ablation technology cannot be cloned or predicted even by the manufacturer, and has a unique special nanostructure morphology, thus generating low-cost and highly reliable PUF features.

[0021] (2) The preparation of the anti-counterfeiting structure provided by the present invention has low cost and scalability: The laser scanning process (such as completing the preparation of an area of 15×15 mm² within 1 minute) greatly reduces the cost compared to traditional nanomanufacturing.

[0022] (3) The anti-counterfeiting structure provided by the present invention can be compatible with flexible substrates (PI, PDMS, PVA), and is applicable to fields such as wearable devices and packaging, with multi-scenario adaptability.

[0023] (4) In the same nanostructure layer of the anti-counterfeiting structure provided by the present invention, bionic columnar or flaky nanostructures are formed by process regulation and selection, combining randomness and controllability.

[0024] (5)The anti-counterfeiting structure provided by the present invention has a multiple anti-counterfeiting verification system: ① A layer of metal Pt is plated on the surface of the anti-counterfeiting structure, and the anti-counterfeiting structure will show a transparent black color, with an obvious light-transmitting effect compared to the non-light-transmitting silver color on the smooth surface; ② The reflectance of the anti-counterfeiting structure is different under the oblique incidence of s-polarized light at 400 nm at an angle of 60°; this result can be measured by an ultraviolet-visible spectrophotometer; ③ Backup cross-verification: By observing the surface nanostructure morphology distribution of the anti-counterfeiting structure through a scanning electron microscope, the similarity between the anti-counterfeiting structure and the backup structure is compared. Description of the Drawings

[0025] Figure 1 is a schematic diagram of the physical unclonable anti-counterfeiting structure based on the bionic nanostructure of the present invention; Figure 2 is a schematic diagram of the preparation process flow of the bionic nanostructure of the present invention; Figure 3 is a schematic diagram of the laser scanning method of the present invention; Figure 4 is a physical picture of the quartz glass and PI with anisotropic flaky nanostructures and the quartz glass and PI with isotropic columnar nanostructures attached to the black adsorption box of the present invention; Figure 5 is an optical photograph of the sample of the area with nanostructures (light-transmitting) and the area without structures (metal color) after depositing metal Pt of the present invention; Figure 6 is a comparison diagram of the visible light band reflectance of the quartz glass with nanostructures and the original quartz glass substrate of the present invention under the incidence of s-polarized light at an angle of 60°; Figure 7 is the SEM morphology diagram and AFM diagram of the anisotropic flaky nanostructures of the present invention; Figure 8 is the SEM morphology diagram and AFM diagram of the isotropic columnar nanostructures of the present invention; Figure 9 is a microscopic morphology comparison diagram of the anisotropic flaky nanostructures and the backup structure of the present invention; Figure 10 is a microscopic morphology comparison diagram of the isotropic columnar nanostructures and the backup structure of the present invention; Figure 11 is a schematic diagram of the structure of the NJUPT anti-counterfeiting label containing two kinds of nanostructures of the present invention.

[0026] Figure 12 is a diagram of the change of the nanostructure morphology with the laser scanning direction of the present invention.

[0027] Reference Signs and Descriptions: 1, substrate; 2, bionic nanostructure layer; 3, anisotropic flaky nanostructures; 4, isotropic columnar nanostructures. Detailed implementation mode

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0029] As Figures 1 - 12 shown, the present invention provides a physically unclonable anti-counterfeiting structure based on a bionic nanostructure. In the present invention, the substrate 1 used for the anti-counterfeiting structure can be rigid quartz glass or flexible PI film. When the substrate 1 of the anti-counterfeiting structure is made of flexible PI film, it can be compatible with rigid substrates and flexible substrates.

[0030] The preparation method of the bionic nanostructure layer in the present invention is as follows: spin-coat and cure a PI film on a glass substrate to make its thickness about 20 µm; use ultraviolet laser to scan the side of the glass substrate without the attached PI film, and control the process parameters during scanning as: energy density 80-98 mJ / cm², the number of scanning times is 100-460 times for unidirectional APN, and for bidirectional it is cross-scanning (the number of scanning times for the X-axis and Y-axis is 37-62 times each), so that nanoscale cavitation occurs at the interface of the PI film in the laser scanning area, making the interface reach the sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate; a thermal release tape is flatly pasted on the PI film; with the assistance of the external force of the thermal release tape, the PI film can be peeled off from the glass substrate.

[0031] Example 1 As Figure 4 shown, an optical photograph of a quartz glass with an anisotropic sheet-like nanostructure 3 in this embodiment, including a substrate 1 composed of quartz glass and the anisotropic sheet-like nanostructure 3 on the substrate 1. The anisotropic sheet-like nanostructure 3 refers to a material structure with a sheet-like shape and different physical properties in different directions at the nanoscale. Through a specific preparation method, the material is precisely controlled at the nanoscale size and forms a columnar morphology.

[0032] The area of the substrate 1 composed of quartz glass is 2 cm * 2 cm, the thickness is 0.5 mm, the thickness of the anisotropic sheet-like nanostructure 3 is 120 nm - 150 nm, and the material for making the anisotropic sheet-like nanostructure 3 is polyimide.

[0033] The preparation process of the anisotropic sheet-like nanostructure 3 in this embodiment is as follows, see Figure 2 (a): Spin-coat and cure a PI film on a glass substrate to a thickness of approximately 20 µm. The specific operations and experimental parameters are as follows: 1. Fix the glass substrate on the vacuum chuck of a spin coater, and drop an appropriate amount of PI solution with a viscosity of 5000 cp in the middle. 2. The spin-coating parameters are 400 r / min * 10 s (acceleration 300) + 1000 r / min * 30 s (acceleration 800). 3. Leveling: Let the wafer stand for 60 - 90 s. 4. Soft bake: Place the wafer on a hot plate and heat at 120 °C for 3 minutes. 5. PI curing: Heat and cure the PI by gradient temperature. The temperature and time settings are 140 °C * 30 minutes + 200 °C * 30 minutes + 300 °C * 90 minutes. Use an ultraviolet laser to scan the side of the glass substrate without the attached PI film. Control the process parameters during scanning as follows: the laser energy density is 89 mj / cm 2 , the number of laser scans is 100 times, the laser scanning direction is unidirectional (along the X-axis), so that cavitation occurs at the interface of the PI film in the laser scanning area, making the interface reach the sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate.

[0034] Flatly attach a thermal release tape on the PI film. Here, the thermal release tape is used as an external force assistance to peel the PI film from the glass substrate.

[0035] Heat the thermal release tape at 110 °C to complete the thermal release process of the PI film, thereby preparing quartz glass and a PI film with an anisotropic flaky nanostructure 3 on the surface.

[0036] After completing the peeling of the PI film, samples (quartz glass and PI film with anisotropic flaky nanostructure 3) with the following process parameters: laser energy density of 89 mj / cm 2 , the number of laser scans is 100 times, and the laser scanning direction is unidirectional (along the X-axis) are attached to a black adsorption box (as Figure 4 shown, a is the quartz glass substrate, b is the PI film substrate).

[0037] Example 2 As Figure 4 shown, an optical photograph of a quartz glass with an anisotropic flaky nanostructure 3 in this example, including a substrate 1 made of quartz glass and the anisotropic flaky nanostructure 3 on the substrate 1. The area of the substrate 1 made of quartz glass is 2 cm * 2 cm, the thickness is 0.5 mm, the thickness of the anisotropic flaky nanostructure 3 is 190 nm - 210 nm, and the material for making the anisotropic flaky nanostructure 3 is polyimide.

[0038] The anisotropic flaky nanostructure 3 of this embodiment is prepared by the following process. See Figure 2 (a): Spin-coat and cure a PI film on a glass substrate to make its thickness about 20 µm. The specific operations and experimental parameters are as follows: 1. Fix the glass substrate on the vacuum chuck of a spin coater, and drop an appropriate amount of PI solution with a viscosity of 5000 cp in the middle. 2. The spin-coating parameters are 400 r / min * 10 s (acceleration 300) + 1000 r / min * 30 s (acceleration 800). 3. Leveling: Let the wafer stand for 60 - 90 s. 4. Soft baking: Place the wafer on a hot plate and heat it at 120 °C for 3 minutes. 5. PI curing: Heat and cure the PI by a gradient temperature. The temperature and time settings are 140 °C * 30 minutes + 200 °C * 30 minutes + 300 °C * 90 minutes. Use an ultraviolet laser to scan the side of the glass substrate without the attached PI film. When scanning, control the process parameters as follows: the laser energy density is 89 mj / cm 2 , the number of laser scans is 340 times, the laser scanning direction is unidirectional (along the X-axis), so that nanoscale cavitation occurs at the interface of the PI film in the laser scanning area, making the interface reach the sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate. Flatly paste a thermal release tape on the PI film. Here, the thermal release tape is used as an external force to assist in peeling the PI film from the glass substrate. Heat the thermal release tape at 110 °C to complete the thermal release process of the PI film, thereby preparing a quartz glass and a PI film with an anisotropic flaky nanostructure 3 on the surface.

[0039] Example 3 As Figure 4 shown, an optical photograph of a quartz glass with an anisotropic flaky nanostructure 3 in this embodiment includes a substrate 1 made of quartz glass and the anisotropic flaky nanostructure 3 on the substrate 1. The area of the substrate 1 made of quartz glass is 2 cm * 2 cm, the thickness is 0.5 mm, the thickness of the anisotropic flaky nanostructure 3 is 140 nm - 280 nm, and the material for making the anisotropic flaky nanostructure 3 is polyimide.

[0040] The anisotropic flaky nanostructure 3 of this embodiment is prepared by the following process. See Figure 2 (a): Spin-coat and cure a PI film on a glass substrate to make its thickness about 20 µm. The specific operations and experimental parameters are as follows: 1. Fix the glass substrate on the vacuum chuck of the spin coater, and drop an appropriate amount of PI solution with a viscosity of 5000 cp in the middle; 2. The spin coating parameters are 400 r / min * 10 s (acceleration 300) + 1000 r / min * 30 s (acceleration 800); 3. Leveling: Let the wafer stand for 60 - 90 s; 4. Soft baking: Place the wafer on a hot plate and heat it at 120 °C for 3 minutes; 5. PI curing: Heat and cure the PI by adopting a gradient temperature, and the temperature and time are set as 140 °C * 30 minutes + 200 °C * 30 minutes + 300 °C * 90 minutes; Use an ultraviolet laser to scan the side of the glass substrate without the attached PI film. When scanning, control the process parameters as follows: the laser energy density is 89 mj / cm 2 , the number of laser scans is 460 times, the laser scanning direction is unidirectional (along the X-axis), so that nanoscale cavitation occurs at the interface of the PI film in the laser scanning area, and the interface reaches the sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate; Flatly paste a thermal release tape on the PI film; here, the thermal release tape is used as an external force assistance to peel the PI film from the glass substrate; Heat the thermal release tape at 110 °C to complete the thermal release process of the PI film, thereby preparing quartz glass and PI film with an anisotropic flaky nanostructure 3 on the surface.

[0041] Characterize the anisotropic flaky nanostructure 3 in the above-mentioned Examples 1, 2, and 3; See Figure 8 , use a scanning electron microscope and an atomic force microscope to characterize the anisotropic flaky nanostructure 3 in the above-mentioned Examples 1, 2, and 3. It can be seen that the anisotropic flaky nanostructure 3 on the surface of the substrate 1 shows a columnar distribution, and the distance between each columnar structure is clearly visible. The distribution of the period and height of the entire structure is random and can be used to construct physically unclonable anti-counterfeiting units.

[0042] Apply the processed anisotropic flaky nanostructure 3 to item anti-counterfeiting, including the following steps: (1) Conduct the first anti-counterfeiting verification as shown in Figure 5 : Deposit a layer of metal Pt on the surface of the quartz glass and PI film with (flaky / columnar) nanostructures. The area with nanostructures will show a transparent black color, with an obvious light-transmitting effect compared to the opaque silver color on the smooth surface. If this phenomenon appears, continue to step (2); if there is no such effect, it is judged as fake; (2) As shown in Figure 6As shown in (d) (the naming rule of the curve legend in the figure: s - polarization light oblique incidence angle - glass placement angle), the second anti - counterfeiting verification is carried out using an ultraviolet - visible spectrophotometer. For the glass with anisotropic flaky nanostructures 3, the reflectivity difference is large under the oblique incidence of s - polarized light in different orientations; it shows obvious differences from the original quartz glass substrate ( Figure 6 (b)). If such results appear when tested with an ultraviolet - visible spectrophotometer, then proceed to step (3). (3) The third anti - counterfeiting verification: As Figure 7 shown in the results, SEM and AFM are used for observation. And information such as morphology height, diameter (width), and spacing is extracted from them. As Figure 9 shown, the morphology data of the sample and the backup structure surface are processed, and data matching is carried out. If the matching result is consistent, it is genuine; if the result does not match, it is fake.

[0043] In the specific verification, if the anti - counterfeiting is genuine, the above three steps are required for verification. If the anti - counterfeiting is fake, it can be terminated according to the steps during verification when a false situation appears.

[0044] Example 4 As Figure 4 shown, an optical photograph of a quartz glass with isotropic columnar nanostructures 4 in this example, including a substrate 1 composed of quartz glass and isotropic columnar nanostructures 4 on the substrate 1. The isotropic columnar nanostructures 4 refer to a material structure that has a columnar shape and exhibits the same physical properties in different directions at the nanoscale. Usually, through specific preparation methods, the material is precisely controlled to the nanoscale size and forms a columnar morphology.

[0045] The area of the quartz glass substrate is 2 cm * 2 cm, the thickness is 0.5 mm, the thickness of the isotropic columnar nanostructures 4 is 200 - 220 nm, and the material is polyimide.

[0046] The preparation process of the isotropic columnar nanostructures 4 in this example is as follows. Refer to Figure 2 (b): Spin - coat and cure a PI film on the glass substrate to make its thickness about 20 µm; the specific operations and experimental parameters are as follows: 1. Fix the glass substrate on the vacuum chuck of the spin coater, and drop an appropriate amount of PI solution with a viscosity of 5000 cp in the middle. 2. The spin - coating parameters are 400 r / min * 10 s (acceleration 300) + 1000 r / min * 30 s (acceleration 800). 3. Leveling: Let the wafer stand for 60 - 90 s. 4. Soft baking: Place the wafer on a hot plate and heat it at 120 °C for 3 minutes. 5. PI curing: Heat and cure PI by adopting gradient temperature. The temperature and time are set as 140°C * 30 minutes + 200°C * 30 minutes + 300°C * 90 minutes; Use ultraviolet laser to scan one side of the glass substrate without the attached PI film, and control the process parameters as follows: Laser energy density is 89 mj / cm 2 , the number of laser scans is 37 times for cross-scanning along the X-axis - Y-axis, and the laser scanning direction is two-way (X-axis - Y-axis cross), so that nanoscale cavitation occurs at the PI interface in the laser scanning area, making the interface reach the sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate; Flatly paste a thermal release tape on the PI film; here, the thermal release tape is used as an external force assistance to peel the PI film from the glass substrate; Heat the thermal release tape at 110 °C to complete the thermal release process of the PI film, thereby preparing quartz glass with an isotropic columnar nanostructure 4 on the surface and the PI film.

[0047] Example 5 As Figure 4 shown, an optical photograph of a quartz glass with an isotropic columnar nanostructure 4 in this example includes a substrate 1 made of quartz glass and the isotropic columnar nanostructure 4 on the substrate 1. The area of the quartz glass substrate is 2 cm * 2 cm, the thickness is 0.5 mm, the thickness of the isotropic columnar nanostructure 4 is 280 - 320 nm, and the material is polyimide.

[0048] The isotropic columnar nanostructure 4 in this example is prepared by the following process. See Figure 2 (b): Spin-coat and cure a PI film on the glass substrate to make its thickness about 20 µm; the specific operations and experimental parameters are as follows: 1. Fix the glass substrate on the vacuum chuck of the spin coater, and drop an appropriate amount of PI solution with a viscosity of 5000 cp in the middle; 2. The spin-coating parameters are 400 r / min * 10 s (acceleration 300) + 1000 r / min * 30 s (acceleration 800); 3. Leveling: Let the wafer stand for 60 - 90 s; 4. Soft baking: Place the wafer on a hot plate and heat it at 120°C for 3 minutes; 5. PI curing: Heat and cure PI by adopting gradient temperature. The temperature and time are set as 140°C * 30 minutes + 200°C * 30 minutes + 300°C * 90 minutes; Use ultraviolet laser to scan one side of the glass substrate without the attached PI film, and control the process parameters as follows: Laser energy density is 89 mj / cm2 The number of laser scans is 51 times for cross-scanning along the X-axis and Y-axis, and the laser scanning direction is bidirectional (X-axis - Y-axis cross), causing nanoscale cavitation at the PI interface in the laser scanning area, bringing the interface to a sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate; A thermal release tape is smoothly pasted on the PI film; here, the thermal release tape is used as an external force assistance to peel the PI film from the glass substrate; The thermal release tape is heated at 110 °C to complete the thermal release process of the PI film, thereby preparing quartz glass with an isotropic columnar nanostructure 4 on its surface and the PI film.

[0049] After the PI film is peeled off, the process parameters are: the laser energy density is 89 mj / cm 2 The number of laser scans is 51 times in the X direction and 51 times in the Y direction, and the laser scanning direction is bidirectional (X-axis - Y-axis cross). The quartz glass with an isotropic columnar nanostructure 4 and the PI film are attached to a black adsorption box (as Figure 4 shown, c is the quartz glass substrate, and d is the PI film substrate).

[0050] Example 6 As Figure 4 shown, an optical photograph of a quartz glass with an isotropic columnar nanostructure 4 in this example includes a substrate 1 composed of quartz glass and the isotropic columnar nanostructure 4 on the substrate 1. The area of the quartz glass substrate is 2 cm * 2 cm, the thickness is 0.5 mm, and the thickness of the isotropic columnar nanostructure 4 is 160 - 220 nm, and the material is polyimide.

[0051] The preparation process of the isotropic columnar nanostructure 4 in this example is as follows. Refer to Figure 2 (b): A PI film is spin-coated and cured on a glass substrate to make its thickness about 20 µm; the specific operations and experimental parameters are as follows: 1. Fix the glass substrate on the vacuum chuck of the spin coater, and drop an appropriate amount of PI solution with a viscosity of 5000 cp in the middle; 2. The spin coating parameters are 400 r / min * 10 s (acceleration 300) + 1000 r / min * 30 s (acceleration 800); 3. Leveling: Let the wafer stand for 60 - 90 s; 4. Soft baking: Place the wafer on a hot plate and heat it at 120 °C for 3 minutes; 5. PI curing: Gradient temperature is used to heat and cure the PI, and the temperature and time settings are 140 °C * 30 minutes + 200 °C * 30 minutes + 300 °C * 90 minutes; The side of the glass substrate without the attached PI film is scanned with an ultraviolet laser, and the process parameters are controlled as follows: the laser energy density is 89 mj / cm 2 , the number of laser scans is 62 times for cross-scanning along the X-axis - Y-axis, and the laser scanning direction is two-way (X-axis - Y-axis cross), so that nanoscale cavitation occurs at the PI interface in the laser scanning area, making the interface reach the sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate.

[0052] A thermal release tape is flatly pasted on the PI film; here, the thermal release tape is used as an external force assistance to peel the PI film from the glass substrate.

[0053] The thermal release tape is heated at 110 °C to complete the thermal release process of the PI film, thereby preparing quartz glass and PI film with an isotropic columnar nanostructure 4 on the surface.

[0054] Characterize the isotropic columnar nanostructures 4 of Examples 4, 5, and 6, Characterize the isotropic columnar nanostructures 4 of Examples 4, 5, and 6 by scanning electron microscopy and atomic force microscopy ( Figure 9 ), and it can be observed that the period and height distribution of this structure are random, thus fully demonstrating the non-clonability of the structure.

[0055] Apply the isotropic columnar nanostructures 4 processed in Specific Examples 4, 5, and 6 to item anti-counterfeiting, including the following steps: (1) As Figure 5 shown, conduct the first-level anti-counterfeiting verification: Coat a layer of metal Pt on the surface of the quartz glass and PI film with (sheet / columnar) nanostructures. The area with nanostructures will show a transparent black color, with an obvious light-transmitting effect compared to the non-light-transmitting silver color on the smooth surface. If this phenomenon appears, continue to step (2); if not, it is judged as fake.

[0056] (2) As Figure 6 (c) shown (the naming rule for the curve legend in the figure: s light oblique incidence angle - glass placement angle), use an ultraviolet-visible spectrophotometer to conduct the third-level anti-counterfeiting verification: For the glass with an isotropic columnar nanostructure 4, the difference in reflectivity is large under the oblique incidence of s-polarized light in different orientations; it shows an obvious difference from the original quartz glass substrate ( Figure 6 (b)). If such results are obtained by testing with an ultraviolet-visible spectrophotometer, continue to step (3).

[0057] (3) Fourth-level anti-counterfeiting verification: As Figure 8 the results shown, use SEM and AFM for observation, and extract information such as morphology height and spacing from it. As Figure 10Perform topography data processing on the surfaces of the sample and the backup structure, and perform data matching. If the matching result is consistent, it is true; if the result does not match, it is false.

[0058] During specific verification, if the anti-counterfeiting is true, the above three steps are required for verification. If the anti-counterfeiting is false, the verification can be terminated when a false situation occurs according to the steps during verification.

[0059] Example 7 As Figure 11 shown, a schematic structural diagram of a quartz glass with a bionic nanostructure layer 2 in the shape of NJUPT in this example includes a quartz glass substrate and the bionic nanostructure layer 2 on the substrate, which includes anisotropic flaky nanostructures 3 in the shape of NJ and isotropic columnar nanostructures 4 in the shape of UPT. The area of the quartz glass substrate is 2 cm * 2 cm, the thickness is 0.5 mm, the thickness of the anisotropic flaky nanostructures 3 is 190 - 210 nm, the thickness of the isotropic columnar nanostructures 4 is 280 - 320 nm, and the material is polyimide.

[0060] The isotropic columnar nanostructures 4 in this example are prepared through the following process. See Figure 2 : Spin-coat and cure a PI film on a glass substrate to make its thickness about 20 µm. The specific operations and experimental parameters are as follows: 1. Fix the glass substrate on the vacuum chuck of a spin coater, and drop an appropriate amount of PI solution with a viscosity of 5000 cp in the middle. 2. The spin-coating parameters are 400 r / min * 10 s (acceleration 300) + 1000 r / min * 30 s (acceleration 800). 3. Leveling: Let the wafer stand for 60 - 90 s. 4. Soft baking: Place the wafer on a hot plate and heat it at 120 °C for 3 minutes. 5. PI curing: Gradually heat the PI for curing, and the temperature and time settings are 140 °C * 30 minutes + 200 °C * 30 minutes + 300 °C * 90 minutes. An opaque aluminum alloy mask plate with a hollowed-out NJUPT logo is pasted on the side of the glass substrate without the attached PI film. First, cover the UPT pattern with another mask plate, and use ultraviolet laser to unidirectionally scan the area of the NJ pattern. Then, cover the NJ pattern with a mask plate and use ultraviolet laser to bidirectionally scan the area of the UPT pattern. The specific operations and experimental parameters are as follows: Align the ultraviolet laser to scan the side of the glass substrate without the attached PI film, control the area as the NJ pattern, and the laser process parameters are: the laser energy density is 89 mj / cm 2, the number of laser scans is 340 times, and the laser scanning direction is unidirectional (along the X-axis), causing nano-scale cavitation at the interface of the PI film in the laser scanning area, bringing the interface to a sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate; adjust the laser irradiation position, and use ultraviolet laser to scan the area aligned with the UPT pattern, and control the laser process parameters as: the laser energy density is 89 mj / cm 2 , the number of laser scans is 62 times for cross-scanning along the X-axis - Y-axis, and the laser scanning direction is bidirectional (X-axis - Y-axis cross), causing nano-scale cavitation at the PI interface in the laser scanning area, bringing the interface to a sub-peeling state. At this time, nanofiber connections are generated at the interface between the PI film and the glass substrate; cut along the peripheral edge of the NJUPT letters, and evenly paste a thermal release tape on the PI film area with the NJUPT pattern; here, the thermal release tape is used as an external force assistance to peel the PI film from the glass substrate; Heat the thermal release tape at 110 °C to complete the thermal release process of the PI film, thereby preparing a quartz glass and a PI film with a biomimetic nanostructure layer 2.

[0061] Example 8 In this example, the influence of the scanning direction on the nanocolumn clusters was tested, as Figure 12 shown. When exploring the effect of the laser scanning direction, a PI sample was divided into four regions. The laser scanning direction in region I is vertically upward, the scanning direction in region II is 45° obliquely upward, the laser scanning direction in region III is two directions, horizontally to the right and vertically upward, and the number of laser irradiations in both directions is half of the total number of irradiations. The scanning direction in region IV is horizontally to the right. The same laser parameters were used for all region scans, with a laser energy density of 105 mJ / cm 2 , and the number of laser irradiations is 40 times.

[0062] The surface of the peeled PI film was observed under an electron microscope, as Figure 12 shown in (a). Four different scanning directions are divided within an area of approximately 2×2 mm, Figure 12 and each region in (a) corresponds to Figure 12 each region with the scanning direction marked in (b), Figure 12(c) are the detailed images of each region under high magnification in the electron microscope. The surface morphologies of the four regions as a whole are nanocolumn structures randomly distributed at the same density. Many nanocolumns form clusters to form a long strip, and these clusters seem to have a directionality. In the figure, some nanocolumn clusters are marked with a dotted box. Most of the nanocolumn clusters in region I are adhered together horizontally, the clusters in region II are in an oblique direction, the clusters in region III are often shorter, and the cluster directions are very random, and most of the cluster directions in region IV are vertical. It is thus found that when the laser scans unidirectionally, the cluster direction of the nanocolumns is perpendicular to the scanning direction of the laser. When the laser scans crosswise, the nanocolumns do not have a fixed cluster direction, and the clusters are shorter, and the nanocolumns tend to be independently distributed.

[0063] The bionic nanostructure layer of this embodiment can achieve nanoscale optical resolution. Its unique nanoscale optical resolution ability stems from the bionic reconstruction of biological micro-nano structures. The randomness of the structure can be used to construct physically unclonable anti-counterfeiting functional units, showing significant technical advantages in the fields of micro-nano scale anti-counterfeiting identification, high-security information encryption, etc. This innovative research provides an important theoretical basis and technical path for the development of a new generation of intelligent anti-counterfeiting materials.

[0064] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A physically unclonable anti-counterfeiting structure based on bionic nanostructures, characterized in that: The invention comprises a substrate (1); a bionic nanostructure layer (2) is arranged on the substrate (1); the bionic nanostructure layer (2) comprises anisotropic sheet-like nanostructures (3) and isotropic columnar nanostructures (4), and the anisotropic sheet-like nanostructures (3) and the isotropic columnar nanostructures (4) are arranged in a random multimodal manner on the same plane.

2. The physical non-clonable anti-counterfeiting structure based on bionic nanostructure according to claim 1 is characterized in that: The thickness of the bionic nanostructure layer (2) is 120 nm-320 nm.

3. The physical non-clonable anti-counterfeiting structure based on bionic nanostructure according to claim 1 is characterized in that: The substrate (1) is a flexible PI film or a rigid quartz glass, and the substrate (1) using a flexible PI film is compatible with a rigid substrate or a flexible substrate.

4. The physical non-clonable anti-counterfeiting structure based on bionic nanostructure according to claim 1, characterized in that: The random multi-modal method includes one or both of an adjustment arrangement method and a proportional relationship method.

5. The physical non-clonable anti-counterfeiting structure based on bionic nanostructure according to claim 1, characterized in that: The material used for the bionic nanostructure layer (2) is polyimide.

6. The physical non-clonable anti-counterfeiting structure based on bionic nanostructure according to claim 1, characterized in that: The anisotropic flaky nanostructure (3) is formed by peeling off after unidirectional scanning of the substrate (1) surface along the X-axis with an ultraviolet laser, and the column spacing of the flaky structure in the anisotropic flaky nanostructure (3) is 100-240nm and the height is 120-260nm.

7. The physical non-clonable anti-counterfeiting structure based on bionic nanostructure according to claim 1 is characterized in that: The isotropic columnar nanostructure (4) is prepared by bidirectionally scanning the surface of the substrate (1) along the X-axis and the Y-axis with an ultraviolet laser, and the columnar diameter of the isotropic columnar nanostructure (4) is in the range of 40-45 nm, the height is 160-320 nm, and the period is 70-130 nm.

8. The physical non-clonable anti-counterfeiting structure based on bionic nanostructure according to claim 3 is characterized in that: The rigid substrate is one of a quartz glass substrate and a silicon wafer, and the flexible substrate is one of PI, PDMS, and PVA.

9. The use of the physical non-clonable anti-counterfeiting structure based on bionic nanostructure according to any one of claims 1 to 8, characterized in that: The anti-counterfeiting structure is applied to the anti-counterfeiting of articles, and the physical non-clonable anti-counterfeiting structure on the PI substrate is attached to the surface of the article as an anti-counterfeiting label.

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