Three-dimensional multi-level structure anti-counterfeit label based on surface projection micro-stereolithography and plasma nano chemical surface patterning and preparation method of three-dimensional multi-level structure anti-counterfeit label

Abstract

The invention discloses a three-dimensional multi-level structure anti-counterfeit label based on surface projection micro-stereo lithography and plasma nano chemical surface patterning and a preparation method, and belongs to the technical field of metal material surface treatment in high-end equipment manufacturing. The invention relates to a surface projection micro stereo lithography method, a colloidal microsphere gas-liquid interface assembly method, a mask etching method, a physical vapor deposition method, a wet transfer method, a chemical synthesis method and the like. And multi-stage regulation and control of the three-dimensional resin structure, the gold nanopore array film and the annular silver nanoparticle assembly in the anti-counterfeit label can be realized. The anti-counterfeit label has rich and adjustable multilevel structure morphology and near field enhancement capability, and becomes a double anti-counterfeit label with optical information and molecular information encryption. According to the method, the three-dimensional patterning process is achieved, and the method has wide application prospects in preparation of micro-nano structure templates through metal surface treatment based on stereolithography and chemical synthesis in the future.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material surface treatment, and specifically relates to a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning and a preparation method thereof. Background Art

[0002] To combat the proliferation of counterfeit products, there is an urgent need to develop new anti-counterfeiting materials that are simple to manufacture, have large data storage capacity, and offer high security. Currently, mainstream anti-counterfeiting materials fall into two main categories. The first category includes overt labels such as watermarks, barcodes, and holograms, which can be verified through simple observation. The second category consists of covert labels, including color-tunable fluorescent anti-counterfeiting labels, structural color anti-counterfeiting labels, surface-enhanced Raman scattering anti-counterfeiting labels, and optical unclonable labels, which often require specialized equipment or databases for verification. Each anti-counterfeiting material has its own advantages and limitations, and meeting all of these requirements remains a significant challenge.

[0003] Among these anti-counterfeiting materials, the three-dimensional anti-counterfeiting system has attracted widespread attention due to its advantages in spatial dimensional encryption. Compared with the traditional two-dimensional system, it can increase the coding capacity by at least one order of magnitude, and can significantly enhance the security level by building a multi-dimensional verification mechanism. However, existing three-dimensional structure preparation technologies such as electron beam lithography, laser-induced forward transfer and two-photon polymerization lithography generally have defects such as complex processes, expensive equipment and low preparation efficiency, which makes it difficult to achieve large-scale production of three-dimensional anti-counterfeiting labels. Therefore, breaking through the limitations of existing technologies and developing a new anti-counterfeiting label and preparation method that can achieve efficient construction of three-dimensional multi-level structures and has the advantages of high coding capacity and low-cost manufacturing has important practical significance for improving the anti-counterfeiting level of goods and safeguarding social and economic order. Summary of the Invention

[0004] The purpose of the present invention is to combine surface projection microstereolithography, wet transfer and plasma nanochemistry methods. First, a three-dimensional resin structure substrate is designed and printed by surface projection microstereolithography, and then a layer of pre-prepared gold nanopore array membrane is transferred on the three-dimensional resin structure substrate by wet transfer. Subsequently, a plasma nanochemistry method is used to induce the growth of annular silver nanoparticle assemblies within the gold nanopore array membrane in a specific area on the three-dimensional resin structure substrate, thereby providing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection microstereolithography and plasma nanochemistry surface patterning and a preparation method.

[0005] The method described in the present invention involves a surface projection microstereolithography method, a colloidal microsphere gas-liquid interface assembly method, a mask etching method, a physical vapor deposition method, a wet transfer method, a chemical synthesis method, and the like. The entire process is simple to operate, low-cost, high-throughput, and highly controllable. The present invention uses software to design a three-dimensional model and utilizes surface projection microstereolithography for printing, thereby controlling the micron-scale structure of the single-layer pattern and three-dimensional structure of the anti-counterfeiting label. The present invention precisely controls the size of the gold nanopore array membrane in the three-dimensional multi-level structure anti-counterfeiting label by controlling the etching time. The present invention utilizes the enhanced effect of the resonance region field under light excitation to perform catalytic reduction of silver nitrate, specifically generating annular silver nanoparticle assemblies within the gold nanopores of the gold nanopore array membrane in a specific region on the surface of the three-dimensional resin structure substrate. This structure has rich and adjustable structural morphology and near-field enhancement capabilities, and can become an anti-counterfeiting label that integrates optical information and molecular information encryption. In addition to preparing this controllable assembly structure anti-counterfeiting label, the use of the above method to realize the three-dimensional patterning process will have broad application prospects in the future surface treatment of metal materials based on stereolithography and chemical synthesis to prepare micro-nanostructure pattern templates.

[0006] The method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning according to the present invention comprises the following steps:

[0007] 1) Designing a 3D model of a 3D resin structure substrate using 3D modeling software, the 3D model comprising the substrate and a 3D pattern with a supporting frame on the substrate, wherein the 3D pattern comprises upper and lower layers of different patterns, the lower layer pattern not contacting the supporting frame and having an area larger than that of the upper layer pattern; then slicing the 3D model using slicing software, and then transferring the sliced multi-layer 3D model to a control system of a surface projection micro-stereolithography system;

[0008] 2) using a surface projection micro-stereolithography system to print a photosensitive resin material layer by layer according to the sliced multi-layer three-dimensional model, and then curing it under the action of ultraviolet light to obtain a three-dimensional resin structure substrate;

[0009] 3) Prefabrication of gold nanopore array membranes: First, a tightly packed polystyrene microsphere array is obtained by self-assembly at the water / air interface; then, the tightly packed polystyrene microsphere array is transferred to a glass substrate, and the diameter of the polystyrene microspheres is reduced by reactive ion etching; then, a 20-100 nm thick gold film is deposited on the obtained polystyrene microspheres by vapor phase thermal deposition, and then the polystyrene microspheres are removed by ultrasonic treatment in toluene for 10-50 seconds, thereby obtaining a gold nanopore array membrane on the glass substrate. The gold nanopores have a size of 0.2-2.9 μm and a period of 0.3-3 μm.

[0010] 4) immersing the gold nanopore array membrane on the glass substrate in step 3) in a 10-20% volume fraction hydrofluoric acid aqueous solution at an angle of 10-30 degrees, thereby releasing the gold nanopore array membrane to the liquid / air interface; using another glass substrate A, transferring the obtained gold nanopore array membrane to a clean water surface to remove residual hydrofluoric acid; then, using another glass substrate B, transferring the gold nanopore array membrane to another clean water surface and collecting it on the three-dimensional resin structure substrate obtained in step 2) to obtain a three-dimensional resin structure substrate covered with the gold nanopore array membrane, and finally drying the three-dimensional resin structure substrate covered with the gold nanopore array membrane at room temperature; the gold nanopore array membrane is divided into region 1 and region 2 on the surface of the three-dimensional resin structure substrate, the gold nanopore array membrane in region 1 is in complete contact with the support frame and the upper pattern surface of the three-dimensional resin structure substrate, and the gold nanopore array membrane in region 2 is not in contact with the frame and the upper pattern surface of the three-dimensional resin structure substrate and is in a suspended state;

[0011] 5) preparing a silver nitrate aqueous solution with a concentration of 0.1 to 10 mM and a sodium citrate aqueous solution with a concentration of 0.1 to 3 wt %; placing the three-dimensional resin structure substrate covered with the gold nanopore array membrane obtained in step 4) in a mixed solution of silver nitrate and sodium citrate in a volume ratio of 1:10 to 50, and irradiating the mixed solution with an LED light source (white light source, wavelength of 300 to 800 nm) for 30 minutes to 5 hours to induce a plasma confined nanochemical reaction, thereby preparing annular silver nanoparticle assemblies of different sizes in the gold nanopore array membrane in region 1, while no annular silver nanoparticle assemblies are generated in the gold nanopore array membrane in region 2, thereby obtaining a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning;

[0012] The gold nanopore array membrane in contact with the resin has an underlying resin structure base for particle nucleation, while the gold nanopores of the suspended gold nanopore array membrane lack nucleation sites for nanoparticles to nucleate. As a result, nanoparticles can only be produced in solution and cannot grow within the pores. The three-dimensional multi-level structure anti-counterfeiting label consists of three parts: a three-dimensional resin structure base, a gold nanopore array membrane, and an annular silver nanoparticle assembly distributed in a specific area.

[0013] 6) Add the concentration of 10 -3 ~10 -9 M methylene blue probe molecule aqueous solution (or other probe molecule aqueous solution), after the aqueous solution is evaporated and dried, the Raman signal of the three-dimensional multi-level structure anti-counterfeiting label area 1 is measured and analyzed and calculated at 1627cm -1 The Raman characteristic peak intensity at is used to establish a fitting relationship curve between the logarithm of the Raman characteristic peak intensity of the methylene blue probe molecule and the logarithm of the concentration of the methylene blue aqueous solution;

[0014] 7) Encryption process based on three-dimensional multi-level structure anti-counterfeiting label: in step 1), the pattern information of the three-dimensional model is controlled (examples are "square and cross" and "BELOW+PFICV" patterns, encryption information 1, which can be changed to other patterns according to actual needs); after the gold nanopore array membrane is covered, the complete pattern information of the three-dimensional multi-level structure anti-counterfeiting label cannot be directly obtained from the reflection mode of the microscope and the scanning electron microscope (the observed results are "cross" pattern and "PFICV" pattern. This is because light irradiation and electron radiation to the upper gold nanopore array membrane and the upper pattern will cause reflection), thereby completing the optical information encryption; then, a methylene blue aqueous solution (with unknown concentration, encryption information 2) is selectively added dropwise to the encryption point of the three-dimensional multi-level structure anti-counterfeiting label (the addition position is controllable, encryption information 3, and the number of encryption points can be increased or decreased according to actual needs); there are multiple three-dimensional encryption patterns in one encryption point, and each three-dimensional encryption pattern has area 1 and area 2. As the aqueous solution evaporates, the color of the methylene blue dye is masked by the diffraction color of the substrate structure, thereby completing the encryption of the molecular information;

[0015] 8) Decryption process based on the three-dimensional multi-level structure anti-counterfeiting label: Observe the complete pattern of the three-dimensional resin structure substrate through the transmission mode of the microscope (examples are the "square and cross" pattern and the "BELOW+PFICV" pattern) to complete the optical information decryption (decryption information 1); then measure the Raman spectrum at the encrypted point position (please note that at this time, due to the different structures of area 1 and area 2, the obtained Raman signal intensity has significant differences. Only when the test point is in area 1 can the correct information be obtained). The Raman spectrum intensity at the characteristic peak position is substituted into the fitting relationship curve of "logarithm of Raman characteristic peak intensity of methylene blue probe molecule and logarithm of concentration of methylene blue aqueous solution" established in step 7) to decrypt the molecular information of the concentration of methylene blue droplets (decryption information 2); after completing the testing of multiple encrypted points, the position distribution information of the encrypted points can be obtained (decryption information 3); thus completing the encryption and decryption process of molecular information and pattern / text information.

[0016] Furthermore,

[0017] The three-dimensional resin structure base described in step 1) is a rectangular parallelepiped structure with a height of 500 to 2000 μm and a length and width of 1 to 20 cm; the three-dimensional pattern is divided into upper and lower layers, the height of a single layer pattern is 5 to 20 μm, the total height of the two layers pattern is 10 to 40 μm, and the length and width of the single layer pattern are 20 to 50,000 μm; the width of the support frame is 10 to 30 μm, the height of the support frame is equal to the total height of the two layers pattern, and the distance between the support frame and the three-dimensional pattern within the frame is 50 to 100 μm; the slicing software slices the three-dimensional model into a multi-layer three-dimensional model according to a single layer thickness of 5 to 20 μm;

[0018] The photosensitive resin material in step 2) is HTL resin, which is a mixture of two methacrylate oligomers, a photoinitiator, and a diluent, and is a purchased commercial product;

[0019] In step 2), the light source for photopolymerization is a 405 nm UV lamp, and the exposure time for a single layer is 1 to 3 seconds;

[0020] The diameter of the polystyrene microspheres in step 3) is 0.3 to 3 μm and they are commercial products purchased;

[0021] In step 3), the reactive ion etching atmosphere is a mixture of oxygen and argon, the oxygen flow rate is 200-300 sccm, the argon flow rate is 50-80 sccm, the etching pressure is 3-10 mTorr, the etching power is 10-50 W, the etching time is 200-600 seconds, and the etching temperature is 5-25° C.

[0022] The vacuum degree of the vapor phase thermal deposition method in step 3) is 5×10 -4 ~2×10 -4 Pa, the deposition rate is The deposition direction is parallel to the basement normal direction;

[0023] In step 5), the LED light source is a white light source with a wavelength of 300 to 800 nm.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning and its preparation method described in the present invention have simple operation steps and high success rate; the entire process is simple to operate, low-cost, high-throughput, and highly controllable;

[0026] Second, the present invention utilizes surface projection micro-stereolithography technology to accurately design patterns at different heights to form three-dimensional structures, with a high degree of customization, which offers significant advantages over traditional two-dimensional patterns designed using methods such as photolithography.

[0027] Third, the present invention uses a pre-prepared gold nanopore array membrane obtained by a wet transfer method to cover the surface of a three-dimensional resin structure substrate. The gold nanopore array membrane and the three-dimensional resin structure substrate surface maintain their original morphology before and after transfer, avoiding the damage to the resin structure during the etching process of traditional colloidal etching methods. At the same time, the gold nanopore array membrane is divided into two regions on the same three-dimensional resin structure substrate. This regional difference increases the difficulty of decrypting the anti-counterfeiting label.

[0028] 4. The present invention utilizes the plasma resonance generated by the interaction between structured light and matter to enhance the confined occurrence of field chemical reactions, which can precisely control the preparation of nanoparticle assemblies; the prepared three-dimensional multi-level structure anti-counterfeiting label has rich and adjustable structural parameters and near-field coupling enhancement capabilities, giving it multi-level information encryption capabilities and higher coding capacity, and has great application value and practical potential in the field of anti-counterfeiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the preparation process of a three-dimensional multi-level structure anti-counterfeiting label;

[0030] Wherein step A is to prepare a three-dimensional resin structure substrate by surface projection micro-stereolithography technology;

[0031] Step B is the release of the gold nanopore array membrane in a hydrofluoric acid aqueous solution;

[0032] Step C is to move the gold nanopore array membrane from the hydrofluoric acid aqueous solution to another clean water surface;

[0033] Step D is collecting the gold nanopore array membrane on the water surface using a three-dimensional resin structure substrate;

[0034] Step E is drying the three-dimensional resin structure substrate covered with the gold nanopore array membrane at room temperature;

[0035] Step F is to prepare a ring-shaped silver nanoparticle assembly in the upper pattern region of the three-dimensional resin structure substrate covered with the gold nanopore array membrane by using a plasma nanochemical reaction;

[0036] Figure 2 Microscope and scanning electron microscope images of two 3D patterns in a 3D multi-level structure anti-counterfeiting label;

[0037] a is a microscope image of a "square and cross" pattern in a three-dimensional resin structure substrate, wherein the inset in the upper right corner is a schematic diagram of the three-dimensional model;

[0038] b is a scanning electron microscope image of the "square and cross" pattern in the three-dimensional multi-level structure anti-counterfeiting label, where the support frame and the "cross" area within the support frame are area 1, and the remaining area within the support frame is area 2;

[0039] c is a locally enlarged scanning electron microscope image of the boxed area in b;

[0040] d is a locally enlarged scanning electron microscope image of the boxed area in c;

[0041] e is a microscope image of the “BELOW+PFICV” pattern in the three-dimensional resin structure substrate, where the inset in the upper right corner is a schematic diagram of the three-dimensional model;

[0042] f is a scanning electron microscope image of the "BELOW+PFICV" pattern in the three-dimensional multi-level structure anti-counterfeiting label, where the support frame and the "PFICV" area within the support frame are area 1, and the remaining area within the support frame is area 2;

[0043] Figure 3 Schematic diagram of optical information encryption and decryption of three-dimensional multi-level structure anti-counterfeiting labels;

[0044] Wherein a is a schematic diagram of a three-dimensional multi-level structure anti-counterfeiting label;

[0045] b is a partial enlarged schematic diagram of the pattern within a single encrypted point in a;

[0046] c is an optical photograph of a three-dimensional multi-level structure anti-counterfeiting label;

[0047] d is a microscope reflection mode photograph of the “square and cross” pattern in the three-dimensional multi-level anti-counterfeiting label;

[0048] e is a microscope reflection mode photograph of the “BELOW+PFICV” pattern in the three-dimensional multi-level anti-counterfeiting label;

[0049] f is a microscope transmission mode photograph of the “square and cross” pattern in the three-dimensional multi-level anti-counterfeiting label;

[0050] g is a microscope transmission mode photograph of the “BELOW+PFICV” pattern in the three-dimensional multi-level anti-counterfeiting label;

[0051] Figure 4 Schematic diagram of molecular information encryption and decryption of three-dimensional multi-level structure anti-counterfeiting labels;

[0052] Where a is the detection of analyte methylene blue solution (concentration 10 -3 ~10 -9 M) surface enhanced Raman scattering spectrum;

[0053] b is methylene blue solution at 1627 cm -1 The relationship curve between the logarithm of the intensity of the Raman characteristic peak and the logarithm of the concentration of the methylene blue probe molecule;

[0054] c is a photo of methylene blue solutions with different concentrations added dropwise at different encryption points;

[0055] d is a photo of the encryption process completed after the droplet dries;

[0056] e is a schematic diagram of decrypting the molecular information of region 1 within the encrypted point;

[0057] f is a schematic diagram of decrypting the molecular information of region 2 within the encrypted point;

[0058] g is the concentration and distribution diagram of methylene blue probe molecules at the encrypted point (correct molecular information);

[0059] h is the concentration and distribution diagram of methylene blue probe molecules at the encrypted points (error molecular information). DETAILED DESCRIPTION

[0060] Example 1: Preparation of a three-dimensional resin structure substrate

[0061] 1) Design of 3D model:

[0062] Computer-aided design software (3Ds Max 2024) was used to design a three-dimensional model of a three-dimensional resin structure substrate. The three-dimensional model consists of a substrate and a three-dimensional pattern array with a border on the substrate. The substrate is a rectangular structure with a height of 1000 μm and a length and width of 1.2 cm. The three-dimensional pattern array consists of two layers of patterns, upper and lower. There are 16 encryption points on the substrate (4×4 array), each of which consists of two patterns: four "square and cross" patterns arranged in four rows and one column (where the "square" is the lower pattern and the "cross" is the upper pattern, both with a height of 20 μm, the length and width of the "square" are 230 μm, and the length of the vertical and horizontal bars of the "cross" are both 230 μm and the width is 80 μm) and 12 "BELOW+PFICV" patterns arranged in six rows and two columns (where "BELOW" is the lower pattern and "PFICV" is the upper pattern, both with a height of 20 μm, and the length of "BELOW" and "PFICV" is 90 μm and the width is 50 μm). The patterns are surrounded by a supporting frame (20 μm high and 15 μm wide). The images are then exported to the STL file format.

[0063] 2) Preparation of 3D resin structure substrate based on surface projection micro-stereolithography printing:

[0064] The 3D model was then sliced using the corresponding slicing software (VoxelDance Additive 4.0) and imported into the control system of a surface projection micro-stereolithography system (MicroArch S230, Shenzhen BMDF New Materials Technology Co., Ltd.). The printing platform and stretch film were leveled, and the light source was focused. A photosensitive resin (HTL resin, purchased from Shenzhen BMDF New Materials Technology Co., Ltd.) was printed layer by layer between the printing platform and the stretch film and then exposed and cured to obtain a 3D resin structure substrate. The thickness of the printed layer was set to 10 μm, the light source wavelength was 405 nm, and the exposure time was set to 2 seconds.

[0065] Example 2: Preparation of a three-dimensional multi-level structure anti-counterfeiting label

[0066] 1) Preparation of monolayer polystyrene colloidal crystals on glass substrate:

[0067] Use a disposable syringe to draw 0.2mL of ethanol and deionized water dispersion of polystyrene microspheres with a diameter of 700nm (purchased from Wuhan Huawei Micro-Technology Co., Ltd.), and use a syringe pump to slowly inject it onto the surface of deionized water pre-added to the culture dish. Let it stand for a while, and then add a 10wt% aqueous solution of sodium dodecyl sulfate along one side of the culture dish to make the polystyrene microspheres form a hexagonal tightly packed monolayer of microspheres. The polystyrene microsphere dispersion remaining in the syringe is recovered for later use. The glass substrate is immersed below the water surface, the tightly packed monolayer microspheres at the air-liquid interface are picked up, and placed on a slope to dry naturally to obtain a multi-scale patterned monolayer polystyrene colloidal crystal substrate;

[0068] 2) Preparation of gold nanopore array membrane:

[0069] The multi-scale patterned monolayer polystyrene colloidal crystal substrate prepared in step 1) was placed in an anisotropic plasma cleaning machine and etched for 300 seconds under the conditions of oxygen and argon atmosphere, gas flow rates of 300 sccm and 50 sccm respectively, etching pressure of 5 mTorr, etching power of 30 W, and etching temperature of 20°C. In this process, the polystyrene microspheres were etched to reduce their volume, and a non-hexagonal tightly packed polystyrene microsphere array on the glass substrate was obtained. The above substrate was placed on the sample stage of the vacuum evaporation coating equipment, with the substrate normal direction parallel to the deposition direction, at 5×10 -4 Pa vacuum, the gold film was deposited by vapor phase thermal evaporation at a deposition rate of The deposition thickness was 50 nm. Finally, the sample was immersed in toluene and sonicated for 30 seconds to remove the polystyrene microspheres, resulting in a gold nanopore array membrane on a glass substrate. The gold nanopores had a size of 530 ± 20 nm and a period of 700 nm.

[0070] 3) Preparation of a three-dimensional resin structure substrate covered with a gold nanopore array membrane:

[0071] The sample prepared in step 2) was immersed in a 10% hydrofluoric acid aqueous solution at a 20° tilt, thereby releasing the gold nanopore array membrane to the liquid / air interface. Another glass substrate A was used to transfer the gold nanopore array membrane to the water surface to remove residual hydrofluoric acid. Then, another glass substrate B was used again to transfer the gold nanopore array membrane to another clean water surface and collected from the three-dimensional resin structure substrate of step 2) of Example 1 to obtain a three-dimensional resin structure substrate covered with a gold nanopore array membrane. The prepared three-dimensional resin structure substrate covered with the gold nanopore array membrane was dried at room temperature for further use. As a membrane material, the gold nanopore array membrane has high mechanical stability and flexibility. When the membrane is fixed by the support structure, the support point will provide a vertical reaction force, directly offsetting the gravity of the membrane itself, while making the stress distribution of the membrane uniform. Therefore, the gold nanopore array membrane is divided into two regions on the surface of the three-dimensional resin structure substrate. Region 1 is the gold nanopore array membrane that is in complete contact with the support frame and central pattern portion of the three-dimensional resin structure substrate, that is, the gold nanopore array membrane that is in complete contact with the three-dimensional resin structure substrate. Region 2 is a suspended gold nanopore array membrane supported by the support frame and central pattern of the three-dimensional resin structure substrate;

[0072] 4) Preparation of three-dimensional multi-level structure anti-counterfeiting labels:

[0073] The sample prepared in step 3) is immersed face-up in 50 mL of a 1 mM silver nitrate aqueous solution and 5 mL of a 1 wt% sodium citrate aqueous solution. An LED light source (white light, wavelength 300-800 nm) is then applied directly above the sample to irradiate the sample for 2 hours to generate a plasma-confined nanochemical reaction. Ring-shaped silver nanoparticle assemblies of varying sizes are thereby prepared within the gold nanopore array membrane in region 1, while no ring-shaped silver nanoparticle assemblies are generated within the gold nanopore array membrane in region 2. The gold nanopore array membrane in contact with the resin has a lower resin structure substrate for particle nucleation, while the gold nanopores of the suspended gold nanopore array membrane lack nucleation sites for nanoparticle nucleation. This results in nanoparticles being generated only in the solution and not growing within the pores, ultimately yielding a three-dimensional multi-level structure anti-counterfeiting label. The three-dimensional multi-level structure anti-counterfeiting label consists of three parts: a three-dimensional resin structure substrate, a gold nanopore array membrane, and ring-shaped silver nanoparticle assemblies distributed in specific regions.

[0074] Example 3: Testing of improving Raman signal detection sensitivity based on a three-dimensional multi-level structure anti-counterfeiting label

[0075] Take the substrate sample in step 4) of Example 2, and add 2 μL of methylene blue aqueous solution (10 -3 ~10 -9 M concentration gradient, the concentration is 10 -3 M, 10 -4 M, 10-5 M, 10 -6 M, 10 -7 M, 10 -8 M and 10 -9 M), after the droplets evaporated and dried naturally, a high-resolution Raman laser spectrometer was used to measure the Raman signals of region 1 at different methylene blue concentrations. The Raman signals at 1627 cm -1 The Raman characteristic peak intensity at is fitted to obtain the relationship curve between the logarithm of the Raman characteristic peak intensity and the logarithm of the probe molecule concentration, which is used as the working curve for subsequent anti-counterfeiting encryption.

[0076] Example 4: Encryption and decryption method based on three-dimensional multi-level structure anti-counterfeiting label

[0077] 1) Encryption process:

[0078] In step 1) of Example 1, the pattern information of the three-dimensional model is controlled (the "square and cross" and "BELOW and PEICV" patterns, encryption information 1, which can be changed to other patterns according to actual needs). After the gold nanopore array membrane is covered, the complete pattern information of the three-dimensional multi-level structure anti-counterfeiting label cannot be directly obtained from the reflection mode of the microscope (the light source and the objective lens are located on the same side of the sample, and the light is reflected back to the objective lens after irradiating the sample surface) and the scanning electron microscope. This is because light irradiation and electron radiation will reflect when they reach the upper gold nanopore array membrane and the upper pattern (the observation results are "cross" pattern and "PFICV" pattern, and the "square" and "BELOW" of the lower layer are not visible), thereby completing the optical information encryption. Then, a methylene blue aqueous solution (unknown concentration, encryption information 2) is selectively added dropwise to the encryption points of the three-dimensional multi-level structure anti-counterfeiting label (4×4 total 16, the addition position is random, encryption information 3, the number of encryption points can be increased or decreased according to actual needs). As the solvent evaporates, the dye color is masked by the structural diffraction color, completing the molecular information encryption;

[0079] 2) Decryption process:

[0080] Using the microscope's transmission mode (where the light source is located below the sample and light passes through the sample and is received by the objective lens above), the complete pattern of the three-dimensional model in step 1)—namely, the "square and cross" pattern and the "BELOW+PEICV" pattern—can be obtained, completing the optical information decryption (decrypted information 1). The Raman spectrum is measured at the encrypted point position of the three-dimensional multi-level structure anti-counterfeiting label during the molecular encryption process. During the test, the position to be tested is observed using a microscope equipped with a Raman spectrum. This not only locates the encrypted point, but also precisely locates Areas 1 and 2 of the three-dimensional encrypted pattern within the encrypted point, completing the test process. The Raman spectrum intensity is substituted into the fitting relationship curve of "the logarithm of the Raman characteristic peak intensity of the methylene blue probe molecule and the logarithm of the concentration of the methylene blue aqueous solution" established in step 7) to decrypt the molecular information, namely, the concentration of the methylene blue droplet (decrypted information 2). Please note that due to the structural differences between Regions 1 and 2, the Raman signal intensities obtained are significantly different. Only when the test point is in Region 1 (e.g., Point 1) can correct information be obtained. However, when the test point is in Region 2 (e.g., Point 2), the structural differences will result in a lower Raman signal intensity, resulting in erroneous information. After testing multiple encrypted points, the positional distribution of the encrypted points (decrypted information 3) can be obtained, thus completing the encryption and decryption process of molecular information and pattern / text information.

[0081] like Figure 1 As shown, the names of the various parts are: surface projection micro-stereolithography system 1, three-dimensional resin structure substrate 2, gold nanopore array membrane 3, glass substrate 4, hydrofluoric acid aqueous solution 5, and ring-shaped silver nanoparticle assembly 6; after steps A to F, the preparation of the three-dimensional multi-level structure anti-counterfeiting label is completed.

[0082] like Figure 2 As shown in (a), the microscope pattern consists of a "square and cross" pattern in a three-dimensional resin structure base, corresponding to the three-dimensional model in the upper right corner illustration; Figure 2 As shown in (b) in the figure, the support frame and the "cross" area within the support frame are area 1, and the rest of the area within the support frame is area 2. Point 1 is located in area 1, and point 2 is located in area 2. Figure 2 As shown in (b), (c) and (d), in region 1, there is an upper pattern support of the three-dimensional resin structure substrate for particle nucleation, resulting in the formation of annular silver nanoparticle assemblies only in region 1; while in region 2, there are no nucleation sites for nanoparticles to nucleate, resulting in nanoparticles that can only be produced in the solution and will not grow in the gold nanopores, so no annular silver nanoparticle assemblies are generated; Figure 2 As shown in (e), the microscope pattern consists of "BELOW and PFICV" patterns in the three-dimensional resin structure base, corresponding to the three-dimensional model in the upper right corner illustration; Figure 2As shown in (f), the support frame and the "PFICV" area within the support frame are area 1, the remaining area within the support frame is area 2, and the ring-shaped silver nanoparticle assembly is only generated in area 1.

[0083] like Figure 3 As shown in (a) and (b), the three-dimensional multi-level structure anti-counterfeiting label consists of an array of 16 encryption points, and the center distance between adjacent encryption points is 2000μm; each encryption point consists of two patterns, namely 4 "square and cross" patterns arranged in four rows and one column (wherein, "square" is the lower layer pattern, "cross" is the upper layer pattern, both are 20μm in height, "square" has a length and width of 230μm, and "cross" has a vertical bar and horizontal bar with a length of 230μm and a width of 80μm) and 12 "BELOW+PFICV" patterns arranged in six rows and two columns (wherein, "BELOW" is the lower layer pattern, "PFICV" is the upper layer pattern, both are 20μm in height, and "BELOW" and "PFICV" have a length of 90μm and a width of 50μm), and a supporting frame (with a height of 20μm and a width of 15μm) is provided around the pattern; each encryption pattern is further divided into area 1 and area 2; as shown in FIG. Figure 3 As shown in (c) in the figure, the encryption points in the three-dimensional multi-level structure anti-counterfeiting label are visible to the naked eye. In addition, during the test, the microscope supporting the Raman spectroscopy is used to observe the position to be tested, which can not only locate the encryption point, but also accurately locate the area 1 and area 2 of the three-dimensional encryption pattern within the encryption point, completing the test process; Figure 3 As shown in (d) in the reflection mode of the microscope, the light source will be reflected back after it hits the uppermost gold nanopore array membrane, and only the pattern information of the upper "cross" can be obtained, but the pattern information of the lower "lower square" cannot be obtained; Figure 3 As shown in (e) in the reflection mode of the microscope, the light source will be reflected back after it hits the uppermost gold nanopore array membrane, and only the pattern information of the upper layer "PFICV" can be obtained, but the pattern information of the lower layer "BELOW" cannot be obtained, thus completing the encryption of optical information; Figure 3 As shown in (f) in the transmission mode of the microscope, the light source is located below the sample. After the light penetrates the sample, it is received by the objective lens above, and the complete pattern information of the upper "cross" and the lower "square" can be obtained. Figure 3 As shown in (g), in the transmission mode of the microscope, the light source is located below the sample. After the light penetrates the sample, it is received by the objective lens above. The complete pattern information of the upper layer "PFICV" and the lower layer "BELOW" can be obtained, thereby completing the decryption of the optical information.

[0084] like Figure 4 As shown in (a), when the analyte concentration is as low as 10 -9Its characteristic Raman peak can still be observed when M is used, proving that the three-dimensional multi-level structure anti-counterfeiting label has the ability to detect trace amounts; Figure 4 As shown in (b), the good linear relationship proves that the three-dimensional multi-level structure anti-counterfeiting label has sensitive quantitative detection capabilities;

[0085] like Figure 4 As shown in (c), by selectively adding different concentrations (e.g., a1 is 10 -6 M and a2 are 10 -8 M and a3 are 10 -4 M and b4 are 10 -4 M and c1 are 10 -4 M and c1 are 10 -7 M and c1 are 10 -8 M and d1 are 10 -3 M and d2 are 10 -8 M and d3 are 10 -6 M, d4 is 10 -5 M, while no methylene blue solution was added at a4, b1, b2, b3 and c4; Figure 4 As shown in (d), after the droplet of methylene blue solution dries, the color of the dye solution at the encryption point is masked by the diffraction color of the base structure, thus completing the molecular information encryption; Figure 4 As shown in (e), the 16 encrypted points in area 1 will be tested (as Figure 2 (b) and Figure 3 Substitute the Raman signal intensity of point 1) in (d) into Figure 4 In the fitting curve of (b), read the logarithm of the reagent concentration corresponding to the signal intensity. Figure 4 As shown in (g) in the figure, the correct logarithm of the concentration of methylene blue solution and the information of the distribution of methylene blue at the encrypted points are obtained (a1 is -6, a2 is -8, a3 is -4, b4 is -4, c1 is -4, c2 is -7, c3 is -8, d1 is -3, d2 is -8, d3 is -6, d4 is -5, a4, b1, b2, b3 and c4 are "-", that is, there is no methylene blue solution), thereby completing the molecular information decryption, where "-8", "-6", "-4" and so on represent the logarithm of the methylene blue concentration (such as points a2, a1, a3), and "-" represents that there is no methylene blue solution at this encrypted point (such as point a4); Figure 4 As shown in (f), the 16 encrypted points in area 2 will be tested (as Figure 2 (b) and Figure 3 Substitute the Raman signal intensity of point 2) in (d) into Figure 4In the fitting curve of (b), the logarithm of the reagent concentration corresponding to the signal intensity is read. Since the Raman enhancement effect of the silver nanoparticle assembly and the gold nanopore array membrane (region 1) is several times that of the gold nanopore array membrane (region 2), the Raman signal at each encrypted point is lower than that in region 1. When the concentration is lower than 10 -6 When M, the Raman signal can be detected in area 1, but not in area 2, that is, points a2, c2, c3, and d2 are “-”. Figure 4 As shown in (h), incorrect information on the concentration of methylene blue solution and the distribution of methylene blue at the encrypted points was obtained (a1 is -8, a3 is -6, b4 is -6, c1 is -6, d1 is -5, d3 is -8, d4 is -7, a2, a4, b1, b2, b3, c2, c3, c4 and d2 are "-").

[0086] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation on the method of the present invention. Any simple modification, equivalent change, and modification of the above embodiment based on the essence of the method of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning, characterized by: The steps are as follows: 1) Designing a 3D model of a 3D resin structure substrate using 3D modeling software, the 3D model comprising the substrate and a 3D pattern with a supporting frame on the substrate, wherein the 3D pattern comprises upper and lower layers of different patterns, the lower layer pattern not contacting the supporting frame and having an area larger than that of the upper layer pattern; then slicing the 3D model using slicing software, and then transferring the sliced multi-layer 3D model to a control system of a surface projection micro-stereolithography system; 2) using a surface projection micro-stereolithography system to print a photosensitive resin material layer by layer according to the sliced multi-layer three-dimensional model, and then curing it under the action of ultraviolet light to obtain a three-dimensional resin structure substrate; 3) Prefabrication of gold nanopore array membranes: First, a tightly packed polystyrene microsphere array is obtained by self-assembly at the water / air interface; then, the tightly packed polystyrene microsphere array is transferred to a glass substrate, and the diameter of the polystyrene microspheres is reduced by reactive ion etching; then, a 20-100 nm thick gold film is deposited on the obtained polystyrene microspheres by vapor phase thermal deposition, and then the polystyrene microspheres are removed by ultrasonic treatment in toluene for 10-50 seconds, thereby obtaining a gold nanopore array membrane on the glass substrate. The gold nanopores have a size of 0.2-2.9 μm and a period of 0.3-3 μm. 4) immersing the gold nanopore array membrane on the glass substrate in step 3) in a 10-20% volume fraction hydrofluoric acid aqueous solution at an angle of 10-30 degrees, thereby releasing the gold nanopore array membrane to the liquid / air interface; Use another glass substrate A to transfer the obtained gold nanopore array membrane to a clean water surface to remove residual hydrofluoric acid; Then, another glass substrate B is used to transfer the gold nanopore array membrane to another clean water surface and collect the three-dimensional resin structure substrate obtained in step 2) to obtain a three-dimensional resin structure substrate covered with the gold nanopore array membrane. Finally, the three-dimensional resin structure substrate covered with the gold nanopore array membrane is dried at room temperature; The gold nanopore array membrane is divided into region 1 and region 2 on the surface of the three-dimensional resin structure substrate. The gold nanopore array membrane in region 1 is in complete contact with the support frame and upper pattern surface of the three-dimensional resin structure substrate, while the gold nanopore array membrane in region 2 is not in contact with the frame and upper pattern surface of the three-dimensional resin structure substrate and is in a suspended state. 5) preparing a silver nitrate aqueous solution with a concentration of 0.1 to 10 mM and a sodium citrate aqueous solution with a concentration of 0.1 to 3 wt %; placing the three-dimensional resin structure substrate covered with the gold nanopore array membrane obtained in step 4) in a mixed solution of silver nitrate and sodium citrate in a volume ratio of 1:10 to 50, and irradiating the mixed solution with an LED light source for 30 minutes to 5 hours to induce a plasma-confined nanochemical reaction, thereby preparing annular silver nanoparticle assemblies of different sizes in the gold nanopore array membrane in region 1, while no annular silver nanoparticle assemblies are generated in the gold nanopore array membrane in region 2; thereby obtaining a three-dimensional multi-level structure anti-counterfeiting label based on surface projection microstereolithography and plasma nanochemical surface patterning; 6) Add the concentration of 10 -3 ~10 -9 M methylene blue probe molecule aqueous solution, after the aqueous solution is evaporated and dried, the Raman signal of the three-dimensional multi-level structure anti-counterfeiting label area 1 is measured, and the analysis and calculation are at 1627cm -1 The Raman characteristic peak intensity at is used to establish a fitting curve of "the logarithm of the Raman characteristic peak intensity of the methylene blue probe molecule and the logarithm of the concentration of the methylene blue aqueous solution"; The encryption process of the three-dimensional multi-level structure anti-counterfeiting label is as follows: in step 1), the pattern information of the three-dimensional model is controlled. After the gold nanopore array membrane is covered, the complete pattern information of the three-dimensional multi-level structure anti-counterfeiting label cannot be directly obtained from the reflection mode of the microscope and the scanning electron microscope, thereby completing the optical information encryption; then, a methylene blue aqueous solution is selectively dripped onto the encryption points of the three-dimensional multi-level structure anti-counterfeiting label. As the aqueous solution evaporates, the color of the methylene blue dye is masked by the diffraction color of the base structure, thereby completing the encryption of the molecular information; The decryption process of the anti-counterfeiting label based on the three-dimensional multi-level structure is as follows: the complete pattern of the three-dimensional resin structure substrate is observed through the transmission mode of a microscope; the Raman spectrum is then measured at the encrypted point position, and the Raman spectrum intensity at the characteristic peak position is substituted into the established "logarithm of the Raman characteristic peak intensity of the methylene blue probe molecule and the logarithm of the concentration of the methylene blue aqueous solution" fitting relationship curve to decrypt the molecular information of the methylene blue droplet concentration; after the complete testing of multiple encrypted points, the position distribution information of the encrypted points can be obtained, thereby completing the encryption and decryption process of molecular information and pattern / text information.

2. The method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning according to claim 1, characterized in that: The three-dimensional resin structure substrate described in step 1) is a rectangular parallelepiped structure with a height of 500 to 2000 μm and a length and width of 1 to 20 cm; the three-dimensional pattern is divided into upper and lower layers, the height of a single layer pattern is 5 to 20 μm, the total height of the two layers of pattern is 10 to 40 μm, and the length and width of the single layer pattern are 20 to 50,000 μm; the width of the support frame is 10 to 30 μm, the height of the support frame is equal to the total height of the two layers of pattern, and the distance between the support frame and the three-dimensional pattern within the frame is 50 to 100 μm; The slicing software slices the three-dimensional model into single-layer slices with a thickness of 5 to 20 μm to form a multi-layer three-dimensional model.

3. The method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning according to claim 1, characterized in that: The photosensitive resin material in step 2) is HTL resin, which is a mixture of two methacrylate oligomers, a photoinitiator and a diluent.

4. The method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning according to claim 1, characterized in that: In step 2), the light source for photopolymerization is a 405 nm ultraviolet lamp, and the exposure time for a single layer is 1 to 3 seconds.

5. The method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning according to claim 1, characterized in that: The diameter of the polystyrene microspheres in step 3) is 0.3 to 3 μm.

6. The method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning according to claim 1, characterized in that: In step 3), the reactive ion etching atmosphere is a mixture of oxygen and argon, the oxygen flow rate is 200-300 sccm, the argon flow rate is 50-80 sccm, the etching pressure is 3-10 mTorr, the etching power is 10-50 W, the etching time is 200-600 seconds, and the etching temperature is 5-25°C.

7. The method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning according to claim 1, characterized in that: The vacuum degree of the vapor phase thermal deposition method in step 3) is 5×10 -4 ~2×10 -4 Pa, the deposition rate is The deposition direction is parallel to the substrate normal.

8. The method for preparing a three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning according to claim 1, characterized in that: In step 5), the LED light source is a white light source with a wavelength of 300 to 800 nm.

9. A three-dimensional multi-level structure anti-counterfeiting label based on surface projection micro-stereolithography and plasma nanochemical surface patterning, characterized by: The invention is prepared by the preparation method according to any one of claims 1 to 8.

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