Preparation method of curved-surface multilayer encryption device integrating thermochromism and infrared thermal imaging

Abstract

The invention belongs to the technical field of information encryption, and provides a preparation method of a curved-surface multi-layer encryption device integrating thermochromism and infrared thermal imaging, different encryption function layers are stacked on a curved surface and integrated into a curved-surface multi-layer information encryption device in a three-dimensional space, the information storage capacity can be effectively improved without increasing the size of the device, and the cost is reduced. High information density, high function density and multi-level information encryption are realized, and higher-level information security is provided; the self-heating conductive layer is integrated inside, compared with a mode of achieving a thermal stimulation effect through external environment heating, the self-heating conductive layer needs smaller power, energy loss is greatly reduced, the heat conduction efficiency is higher, and the efficiency problem of information encryption and decryption caused by heat conduction delay is effectively solved; meanwhile, the supporting framework is preferentially formed, and the laser in-situ curing technology is combined, so that compared with extrusion type and spraying type curved surface film preparation technologies, the method has the advantages that the dielectric solution is prevented from sliding on the curved surface substrate, and the problem that the curved surface dielectric film is manufactured unevenly is effectively solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of information encryption, and in particular relates to a method for preparing a curved multi-layer encryption device integrating thermochromism and infrared thermal imaging. Background Art

[0002] Thermally responsive encryption devices are widely used in the fields of information encryption and anti-counterfeiting due to their low cost, abundant sources, simple and easy control, and dynamic data encryption and decryption capabilities.

[0003] Due to their unique nature, multi-layer thermal stimulus-responsive encryption devices require separate mold creation, printing, and production processes. Existing curved surface manufacturing technologies suffer from low manufacturing precision and poor multi-layer alignment accuracy, making it difficult to simplify and cost-effectively manufacture these devices. Furthermore, these devices often use external heating to achieve the thermal stimulation effect. However, due to the complex curved surface structure, precise control of the localized heating temperature is difficult, leading to information decryption failures. Furthermore, the transmission of heat from the external environment to the thermally responsive material within the device is delayed, affecting the efficiency of information encryption and decryption. Summary of the Invention

[0004] In order to solve the above problems, the present invention proposes a method for preparing a curved multi-layer encryption device integrating thermochromism and infrared thermal imaging. The present invention is based on single-layer information encryption, stacks different encryption functional layers on a curved surface and integrates them into a curved multi-layer information encryption device in three-dimensional space. The information storage capacity can be effectively improved without increasing the size of the device, achieving high information density, high functional density and multi-level information encryption, and providing a higher level of information security; a self-heating conductive layer is integrated internally. Compared with the method of achieving thermal stimulation effect by heating the external environment, the self-heating conductive layer requires less power, greatly reduces energy loss, and has a faster heat conduction efficiency, effectively solving the efficiency problem of information encryption and decryption caused by heat conduction delay; at the same time, the support skeleton is preferentially formed and combined with laser in-situ curing technology. Compared with the extrusion and spraying curved film preparation technologies, this method avoids the slippage of the dielectric solution on the curved substrate, effectively solving the problem of uneven manufacturing of the curved dielectric film.

[0005] To achieve the above objectives, the present invention provides a method for preparing a curved multi-layer encryption device integrating thermochromism and infrared thermal imaging, which adopts the following technical solutions: A method for preparing a curved multi-layer encryption device integrating thermochromism and infrared thermal imaging, comprising: A sacrificial layer solution is coated on a surface of a predetermined curved substrate to prepare a curved sacrificial layer substrate; and a substrate layer is prepared on the curved sacrificial layer substrate. The preparation of the substrate layer includes: constructing a flexible support skeleton, depositing and simultaneously photocuring the substrate material in the reserved cavity area to complete the preparation of a uniform substrate layer. Printing a self-heating conductive layer on the substrate layer; printing a dielectric isolation layer on the self-heating conductive layer, and printing an infrared information functional layer on the dielectric isolation layer; printing a second dielectric isolation layer on the infrared information functional layer; and printing a thermochromic encryption functional layer on the second dielectric isolation layer; Printing a sealing protective layer on the thermochromic encryption functional layer.

[0006] Furthermore, the preset curved surface substrate is subjected to dust-free treatment, and a sacrificial layer solution having a uniform thickness is coated on the surface of the curved surface substrate and solidified to complete the preparation of the sacrificial layer.

[0007] Furthermore, the hemispherical object was placed in an isopropyl alcohol solution for ultrasonic cleaning for 6 minutes, then placed in deionized water for ultrasonic cleaning for 5 minutes to remove the residual isopropyl alcohol solution, and finally blown dry with nitrogen; a thin and uniform layer of cellulose solution was coated on its surface using the pull-up coating method, and the sample was placed in a heating box and heated at 85°C for 15 minutes to complete the curing of the sacrificial layer.

[0008] Furthermore, the coating methods used to prepare the sacrificial layer substrate include but are not limited to spraying, spin coating, pull-up coating and 3D printing.

[0009] Furthermore, preparing the substrate layer includes: selecting biodegradable plastic as a flexible substrate material, using a multi-material conformal 3D printer, forming a support skeleton and combining it with in-situ curing technology to complete the preparation of the biodegradable plastic substrate layer on the surface of the sacrificial layer.

[0010] Furthermore, the elastomeric polymer used to prepare the substrate layer includes but is not limited to polydimethylsiloxane, degradable plastics and thermoplastic polyurethane rubber; the laser heater used for photocuring includes but is not limited to ultraviolet laser, fiber laser and carbon dioxide laser.

[0011] Furthermore, printing the self-heating conductive layer includes: based on the substrate layer, printing the conductive heating layer with a stretchable conductive paste according to a preset conductive pattern, and performing sintering and conductive treatment to complete the preparation of the conductive heating layer.

[0012] Furthermore, the printing material is selected as a thermochromic material with a mass ratio of polydimethylsiloxane, cross-linking agent and thermochromic microcapsules of 10g:1g:0.5g respectively; using a multi-material conformal 3D printer, the thermotropic functional material is deposited on the substrate by preferentially forming the support skeleton and combining it with in-situ curing technology. After the program is completed, the preparation of the first layer of thermochromic information encryption layer is completed.

[0013] Furthermore, printing the infrared information functional layer includes: using a stretchable conductive paste to print an infrared information pattern on the surface of the dielectric layer according to a preset pattern, and sintering and conducting the pattern after printing is completed.

[0014] Furthermore, printing the packaging protective layer includes: using degradable plastic as a packaging material to print the packaging layer, heating the entire sample to 125° C. for 40 minutes, curing the entire device, and completing the preparation of the encryption device after curing.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention coats a layer of sacrificial layer solution on a preset curved surface substrate to prepare a curved surface sacrificial layer substrate; prepares an underlayer on the curved surface sacrificial layer substrate; prints a self-heating conductive layer on the underlayer; prints a dielectric isolation layer on the self-heating conductive layer, and prints an infrared information functional layer on the dielectric isolation layer; prints a second dielectric isolation layer on the infrared information functional layer; prints a thermochromic encryption functional layer on the second dielectric isolation layer; and prints an encapsulation protection layer on the printed thermochromic encryption functional layer; wherein, preparing the underlayer includes: constructing a flexible support skeleton, depositing and simultaneously photocuring the substrate material in the reserved cavity area to complete the preparation of a uniform underlayer; the present invention is based on single-layer information encryption, stacking different encryption functional layers on the curved surface and integrating them The curved multi-layer information encryption device in three-dimensional space can effectively improve the information storage capacity without increasing the size of the device, achieve high information density, high functional density and multi-level information encryption, and provide a higher level of information security; a self-heating conductive layer is integrated inside. Compared with the method of achieving thermal stimulation effect by heating the external environment, the self-heating conductive layer requires less power, greatly reduces energy loss, and has a faster heat conduction efficiency, which effectively solves the efficiency problem of information encryption and decryption caused by heat conduction delay; at the same time, the support skeleton is preferentially formed and combined with laser in-situ curing technology. Compared with the extrusion and spraying curved thin film preparation technology, this method avoids the slippage of the dielectric solution on the curved substrate, effectively solving the problem of uneven manufacturing of curved dielectric films.

[0016] 2. The present invention can realize the manufacture of a curved multi-layer flexible encryption system that integrates self-heating thermochromic encryption and infrared thermal imaging encryption functions, and has the advantages of low manufacturing cost, simple process and large-scale manufacturing.

[0017] 3. Through structural design, the present invention achieves high-density information storage and multi-level dynamic encryption functions compared to traditional single-layer thermochromic devices, significantly improving the complexity of anti-counterfeiting identification and the system's anti-cracking capabilities, providing a new solution for the field of information security.

[0018] 4. The present invention adopts multi-material conformal 3D printing technology, which can realize macro-micro cross-scale manufacturing, and can realize both small-scale miniaturization and macro-large-area manufacturing; the materials used are clean, green, environmentally friendly, pollution-free and recyclable, and the manufacturing process does not produce waste gas, wastewater and other pollutants, which is environmentally friendly; the manufacturing process is simple, and can achieve low-cost, batch, customized and integrated manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the specification of this embodiment are used to provide a further understanding of this embodiment. The schematic embodiments and descriptions of this embodiment are used to explain this embodiment and do not constitute an improper limitation on this embodiment.

[0020] Figure 1 This is a design principle diagram of the curved multi-layer flexible encryption system of the present invention; Figure 2 The preparation process of the thermochromic functional material of the present invention; Figure 3 This is a physical diagram of the preparation of the thermochromic functional material of the present invention; Figure 4 The preparation process of the infrared thermal imaging curved multi-layer flexible encryption device of the present invention; Figure 5 The invention relates to the manufacture of the infrared thermal imaging and thermochromic composite curved surface multi-layer encryption device; Figure 6 The invention discloses a process flow for preparing a curved dielectric film by preferentially shaping a support skeleton and combining it with an in-situ curing technology. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0023] Thermally responsive encryption devices are widely used in information encryption and anti-counterfeiting due to their low cost, abundant availability, ease of control, and dynamic data encryption and decryption capabilities. Two materials are commonly used in the fabrication of thermally responsive encryption devices: thermochromic and thermofluorescent materials. Thermochromic materials change color with temperature and offer advantages such as being pollution-free, vivid, and environmentally friendly. However, current thermochromic materials can only achieve a dual-mode color change triggered by thermal stimulation. Thermofluorescent materials offer low thermal stimulation costs but require complex molecular design and synthesis processes. Furthermore, most thermochromic fluorescent materials can only achieve a dual-mode color change, resulting in single-channel decryption and low security levels, posing security risks. Furthermore, most current thermally responsive encryption devices have only a single encryption layer and can only achieve a dual-mode response triggered by thermal stimulation. This limits their information storage capacity, making them difficult to meet the demand for high-information-density encryption devices. Furthermore, they require external heating and involve complex manufacturing processes, significantly hindering the further development of these devices.

[0024] To meet the growing demand for high-density information storage and higher-level encryption security, researchers have conducted in-depth research on highly integrated information encryption technologies. These efforts have focused on the following: first, synthesizing novel thermosensitive materials capable of multimodal changes; and second, integrating stimuli-responsive materials such as thermochromic fluorescent and thermochromic materials into a single two-dimensional surface through structural design to achieve multi-level information encryption. While these approaches can achieve high-density storage, multi-level information exchange, and encryption in a two-dimensional plane, the synthesis of these novel thermoresponsive materials requires complex molecular synthesis processes. Furthermore, as information encryption devices evolve toward miniaturization, high functional density, and curved applications, the limited storage capacity of a single two-dimensional encryption layer is no longer sufficient. Further research has revealed that vertically stacking different encryption functional layers and integrating them into a three-dimensional space can effectively increase information storage capacity without increasing device size, enabling more complex and advanced functionality and higher levels of information security. However, the large-scale application of these multi-layered, thermo-responsive encryption devices still faces two key challenges. First, due to the uniqueness of encryption devices, they require separate mold opening, printing, and production. Existing curved surface manufacturing technologies suffer from low manufacturing precision and poor multi-layer alignment accuracy, making it difficult to simplify and cost-effectively manufacture curved multi-layer thermal stimulus-responsive encryption devices. Second, thermal stimulus-responsive encryption devices often use external environmental heating to achieve thermal stimulation effects. Due to the complex curved surface structure, it is difficult to accurately control the local heating temperature, resulting in information decryption failures. Furthermore, there is a delay in the transmission of the external environment to the thermally responsive material inside the encryption device, which affects the efficiency of information encryption and decryption.

[0025] In order to solve at least one of the above problems, the present invention provides a method for preparing a curved multi-layer encryption device integrating thermochromism and infrared thermal imaging, which adopts an internally integrated self-heating conductive layer to realize programmable selective heating, low-pressure rapid heating, and precise adjustment of temperature gradient changes, effectively solving the decryption failure caused by the difficulty in accurately controlling the local heating temperature and the efficiency problem of information encryption and decryption caused by heat conduction delay; constructing a support skeleton according to precise path design, utilizing a multi-material conformal 3D printing manufacturing process, combined with laser original curing technology, to achieve uniform manufacturing of curved dielectric films; finally, through laser precise alignment and multi-nozzle linkage, low-cost and customized manufacturing of high-alignment accuracy and high-stability curved multi-layer flexible encryption equipment is achieved; the manufacture of a curved multi-layer flexible encryption system integrating self-heating thermochromic encryption and infrared thermal imaging encryption functions can be realized, with the advantages of low manufacturing cost, simple process and large-scale manufacturing.

[0026] The materials used in the preparation method of this embodiment mainly include thermochromic materials, flexible / stretchable conductive pastes, and elastomeric polymers. The preparation method includes: S1. Preparation of curved sacrificial layer substrate: After dust-free preparation of the pre-designed curved substrate, a thin, uniform layer of sacrificial layer solution is applied to the surface and cured, completing the preparation of the sacrificial layer. This sacrificial layer ensures that curved, multi-layered flexible, and densely packed devices can be peeled off without damage after fabrication, allowing them to be transferred to specialized applications where direct molding is not feasible, thus expanding their scope of application.

[0027] Optionally, the coating method used to prepare the sacrificial layer substrate includes but is not limited to spray coating, spin coating, pull-up coating, and 3D printing. The sacrificial layer solution includes but is not limited to water-soluble sacrificial materials.

[0028] S2. Preparation of substrate layer: Based on multi-material conformal 3D printing, according to the preset precise design path, assisted by laser in-situ curing, the flexible support skeleton is first constructed, and then the substrate material is selectively deposited in the reserved cavity area and the synchronous light curing technology is used to complete the preparation of the uniform substrate layer.

[0029] Optionally, the elastomeric polymer used to prepare the substrate layer includes but is not limited to polydimethylsiloxane (PDMS), Ecoflex, and TPU. Laser heaters used for photocuring include but are not limited to UV lasers, fiber lasers, and carbon dioxide lasers.

[0030] S3. Printing self-heating conductive layer: Based on the substrate layer, according to the preset conductive pattern, the conductive heating layer is printed with a stretchable conductive paste and sintered to perform conductive treatment to complete the preparation of the conductive heating layer.

[0031] Optionally, the flexible / stretchable conductive paste used includes but is not limited to stretchable conductive silver paste, stretchable conductive copper paste, and stretchable conductive polymer, etc. Printing the self-heating conductive layer requires producing interlayer interconnecting wires so that the heating function layer and the infrared information function layer form an electrical connection.

[0032] S4. Printing a dielectric isolation layer: According to the preset design path, the dielectric isolation layer is prepared as described in step S2 to isolate the self-heating conductive layer from the infrared digital functional layer to be printed below.

[0033] S5. Printing infrared information functional layer: Printing infrared information pattern on the surface of dielectric layer according to preset pattern using stretchable conductive paste, and sintering and conducting treatment after printing.

[0034] Optionally, the infrared information functional layer printing process should ensure that the preset path passes through the interlayer interconnection wires to form a stable electrical connection. Infrared information patterns include but are not limited to various QR codes and graphics.

[0035] S6. Printing the second dielectric isolation layer: According to the precise path design, the second dielectric isolation layer is prepared as described in step S4. It isolates its infrared information functional layer from the thermochromic encryption functional layer.

[0036] S7. Printing thermochromic encryption functional layer: forming a specific encryption pattern through multi-material conformal 3D printing of thermochromic materials.

[0037] Optionally, the thermochromic material includes but is not limited to conventionally printed thermochromic materials, or materials prepared by mixing thermochromic microcapsules and elastomeric polymers in a certain proportion.

[0038] S8. Printing a packaging protection layer: Printing an elastomeric polymer on the top layer to encapsulate and protect the system.

[0039] Example 1: This embodiment provides a method for preparing a curved multi-layer encryption device integrating thermochromism and infrared thermal imaging, comprising: S1. Preparation of sacrificial layer substrate: S1.1. Select a high-quality, smooth hemispherical object as the curved surface substrate. First, ultrasonically clean the hemispherical object in an isopropyl alcohol solution for 6 minutes. Then, ultrasonically clean the object in deionized water for 5 minutes to remove any residual isopropyl alcohol. Finally, blow dry the object with nitrogen.

[0040] S1.2. Select a cellulose solution as the sacrificial layer solution. Apply a thin, uniform layer of cellulose solution to the surface using the pull-up coating method. Heat the sample in a heating oven at 85°C for 15 minutes to cure the sacrificial layer.

[0041] S2. Preparation of substrate layer: Optionally, a biodegradable plastic (Ecoflex) is selected as the flexible substrate material, and a multi-material conformal 3D printer is used to prepare the Ecoflex substrate layer on the surface of the sacrificial layer by preferentially molding the support skeleton and combining it with in-situ curing technology.

[0042] S3. Preparing a thermochromic information encryption layer: S3.1. In this embodiment, the information pattern uses a QR code as an example. The printing material is a thermochromic material prepared independently, with a mass ratio of PDMS, a crosslinker, and thermochromic microcapsules of 10g:1g:0.5g, respectively. These materials are named PTM (PTM-31 (blue-to-white transition at 31°C), PTM-35 (white-to-blue transition at 35°C), and PTM-60 (white-to-blue transition at 60°C).

[0043] S3.2. After setting the printing parameters, run the printing program and use a multi-material conformal 3D printer to deposit the thermotropic functional material PTM-31 on the substrate by preferentially forming the support skeleton and combining it with in-situ curing technology. After the program is completed, the preparation of the first layer of thermochromic information encryption layer is completed.

[0044] S4. Preparing a dielectric isolation layer: Optionally, Ecoflex is selected as the dielectric isolation material, and an Ecoflex dielectric isolation layer is prepared according to the technology described in step S2 (in preparation for the preparation of the curved multi-layer thermochromic information encryption layer). After the program is completed, the preparation of the dielectric layer is completed.

[0045] S5. Preparing a second thermochromic information encryption layer: Optionally, according to the process described in step 3, a second layer of encrypted information is printed using the thermochromic functional material PTM-35 according to the pattern set in the QR code.

[0046] S6. Preparing a second dielectric isolation layer: As described in step S4, a second dielectric isolation layer is printed.

[0047] S7. Preparing a third thermochromic information encryption layer: Optionally, according to the process described in step S5, the third layer of encrypted information is printed using the thermochromic functional material PTM-60 according to the pattern set in the QR code.

[0048] S8. Prepare encapsulation layer: Optionally, Ecoflex is used as the packaging material to print the packaging layer. After the program is completed, the entire sample is placed in a drying oven and the heating temperature is set to 125°C and the time is set to 40 minutes. The entire device is thoroughly cured. After the curing is completed, the preparation of the encryption device is completed.

[0049] This embodiment develops a thermochromic functional material with reversible and dynamic conversion properties by using PDMS, a crosslinking agent and thermochromic microcapsules. The preparation process of the thermochromic functional material is as follows: Figure 2 As shown in Figure 3, the material combines the advantages of PDMS and thermochromic microcapsules.

[0050] Example 2: This embodiment provides a method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging. Figure 4 shown.

[0051] S1. Preparation of sacrificial layer substrate: S1.1. Select a high-quality smooth hemispherical object as the curved surface substrate and a cellulose solution as the sacrificial layer solution.

[0052] S1.2. After dust-free treatment, blow dry the substrate with nitrogen. Spin coat the float glass with a thin and uniform layer of cellulose solution. Heat the sample in a drying oven at 70°C for 10 minutes until the sacrificial layer is cured.

[0053] S2. Preparation of substrate layer: PDMS was selected as the flexible substrate material, and a multi-material conformal 3D printer was used to prepare the PDMS substrate layer on the surface of the sacrificial layer by preferentially molding the support skeleton and combining it with in-situ curing technology.

[0054] S3. Preparing an infrared information encryption layer: S3.1. The conductive circuit patterns in this embodiment are the "□" pattern, the "○" pattern, and the "△" pattern. The printing paste is a stretchable silver paste independently prepared by the laboratory.

[0055] S3.2. After setting the printing parameters, run the printing program to print the first layer of encrypted graphics “□”.

[0056] S4. Preparation of dielectric layer: PDMS is selected as the dielectric layer material, and a PDMS dielectric layer is prepared according to step S2 (isolating the two information encryption layers and preparing for the subsequent preparation of the infrared information encryption layer). After the program is completed, the preparation of the dielectric layer is completed.

[0057] S5. Prepare the second infrared information encryption layer: According to the preset route, the pattern is accurately printed so that its path passes through the interlayer interconnection wires to form an electrical connection, and the second layer of encrypted pattern "○" is printed according to the process described in step S3.

[0058] S6. Preparing a second dielectric layer: As described in step S4, a second dielectric layer is printed.

[0059] S7. Prepare the third infrared information encryption layer According to the process described in step S5, the third layer of encrypted pattern "△" is printed.

[0060] S8. Prepare encapsulation layer: The encapsulation layer was printed using PDMS as the encapsulation material. After the program was completed, the entire sample was placed in a drying oven and heated to 125°C for 40 minutes to thoroughly cure the entire device. After this treatment, the entire device was peeled off from the cellulose-hemispherical substrate, completing the fabrication of a curved, multi-layered, flexible infrared thermal imaging encryption device.

[0061] This embodiment is to achieve graphical infrared thermal imaging encryption to avoid simple deciphering under conventional logic. By adjusting the printing speed and printing pressure, the extrusion amount of stretchable silver paste during printing is controlled. By controlling the change of the deposition cross-section without changing the line width, the resistance and heat generation of the wire are controlled, and an unconventional light and dark sequence under infrared thermal imaging is achieved. The logical combination of graphics and numbers is completed, and the final answer to the decryption is obtained, that is, the brightness and darkness of the infrared imaging are sorted from high to low as "○", "△", and "□", rather than the "□", "○", and "△" obtained according to the isotropy principle of the wire material (that is, the wire resistance is proportional to the length, combined with the graphical nested design and circumference size).

[0062] Example 3: This embodiment provides a method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging. Figure 5 shown.

[0063] S1. Preparation of sacrificial layer substrate: S1.1. Select a high-quality, smooth hemispherical object as the curved surface substrate. First, ultrasonically clean the hemispherical object in an isopropyl alcohol solution for 6 minutes. Then, ultrasonically clean the object in deionized water for 5 minutes to remove any residual isopropyl alcohol. Finally, blow dry the object with nitrogen.

[0064] S1.2. Select polyvinyl alcohol solution as the sacrificial layer solution. Spray a thin, even layer of polyvinyl alcohol solution onto the surface. Place the sample in a drying oven at 70°C for 20 minutes to cure the sacrificial layer.

[0065] S2. Preparation of substrate layer: PDMS was selected as the flexible substrate material, and a multi-material conformal 3D printer was used to prepare the PDMS substrate layer on the surface of the sacrificial layer by preferentially molding the support skeleton and combining it with in-situ curing technology.

[0066] S3. Preparation of self-heating conductive functional layer: S3.1. Based on the PDMS substrate layer, select the laboratory-prepared flexible / stretchable conductive silver paste and call up the preset conductive pattern program.

[0067] S3.2. After setting the printing parameters, run the printing program and complete the preparation of the self-heating conductive functional layer by combining the in-situ curing technology.

[0068] S4. Preparation of dielectric layer: Select PDMS as the dielectric layer material and prepare the PDMS dielectric layer according to the technology described in step S2 (to isolate the conductive heating layer from the information encryption layer and prepare for the subsequent preparation of the infrared information encryption layer). After the program is completed, the preparation of this layer is completed.

[0069] S5. Preparation of infrared information encryption layer S5.1. Call up the infrared information encryption pattern and select the stretchable silver paste independently configured by the laboratory as the printing paste.

[0070] S5.2. After setting the printing parameters, run the printing program to print the infrared information encryption layer. At the vertical interconnection, use climbing interlayer interconnection wires to achieve electrical connection between the self-heating conductive functional layer and the wire circuit infrared information functional layer.

[0071] S6. Preparing a second dielectric layer: Print the second dielectric isolation layer according to step S4.

[0072] S7. Preparing the first thermochromic encryption functional layer: S7.1. The information pattern used in the thermochromic encryption layer is a QR code. The printing materials used are thermochromic materials independently prepared by the laboratory: PTM-31 (transforms from blue to white at 31°C), PTM-35 (transforms from white to blue at 35°C), and PTM-60 (transforms from white to blue at 60°C).

[0073] S7.2. After setting the printing parameters, run the printing program and deposit the thermotropic functional material PTM-60 on the substrate through the multi-material conformal 3D printer. Combined with the in-situ curing technology, the preparation of the first layer of thermochromic encryption functional layer is completed.

[0074] S8. Prepare the second thermochromic encryption functional layer According to the process parameters described in step S7, the second layer of encrypted information is printed using the thermochromic functional material PTM-35 according to the pattern set in the QR code.

[0075] S9, preparing the third isolation layer: As described in step S6, a third isolation layer is printed using PDMS material.

[0076] S10, preparing a third thermochromic information encryption layer: According to the process described in step S7, the third layer of encrypted information is printed using the thermochromic functional material PTM-31 according to the pattern set in the QR code.

[0077] S11, preparing the encapsulation layer: The encapsulation layer was printed using PDMS as the encapsulation material. After the program was completed, the entire sample was placed in a drying oven and heated to 125°C for 40 minutes. After processing, the entire device was peeled off from the polyvinyl alcohol-hemispherical substrate, completing the fabrication of a curved multilayer flexible device with integrated thermochromic and infrared thermal imaging encryption.

[0078] The above description is merely a preferred embodiment of this embodiment and is not intended to limit this embodiment. Those skilled in the art will readily appreciate that this embodiment may be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this embodiment shall be within the scope of protection of this embodiment.

Claims

1. A method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging, characterized in that: include: Coating a layer of sacrificial layer solution on the surface of a preset curved substrate to prepare a curved sacrificial layer substrate; Preparing a substrate layer on the curved sacrificial layer substrate; wherein preparing the substrate layer includes: constructing a flexible support skeleton, depositing and simultaneously photocuring the substrate material in the reserved cavity area to complete the preparation of a uniform substrate layer; Printing a self-heating conductive layer on the substrate layer; printing a dielectric isolation layer on the self-heating conductive layer, and printing an infrared information functional layer on the dielectric isolation layer; printing a second dielectric isolation layer on the infrared information functional layer; and printing a thermochromic encryption functional layer on the second dielectric isolation layer; Printing a sealing protective layer on the thermochromic encryption functional layer.

2. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 1, wherein: The preset curved surface substrate is subjected to dust-free treatment, and a thin and uniform layer of sacrificial layer solution is coated on the surface of the curved surface substrate and solidified to complete the preparation of the sacrificial layer.

3. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 2, wherein: The hemispherical object was ultrasonically cleaned in isopropyl alcohol solution for 6 minutes, then ultrasonically cleaned in deionized water for 5 minutes to remove the residual isopropyl alcohol solution, and finally blown dry with nitrogen. A thin and uniform layer of cellulose solution was coated on its surface using the pull-up coating method. The sample was placed in a heating box and heated at 85°C for 15 minutes to complete the curing of the sacrificial layer.

4. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 2, wherein: The coating methods used to prepare the sacrificial layer substrate include but are not limited to spray coating, spin coating, pull-up coating and 3D printing.

5. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 1, wherein: The preparation of the substrate layer includes: selecting biodegradable plastic as a flexible substrate material, using a multi-material conformal 3D printer, forming a support skeleton and combining it with in-situ curing technology to complete the preparation of the biodegradable plastic substrate layer on the surface of the sacrificial layer.

6. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 5, wherein: The elastomeric polymer used to prepare the substrate layer includes but is not limited to polydimethylsiloxane, degradable plastics and thermoplastic polyurethane rubber; the laser heater used for photocuring includes but is not limited to ultraviolet laser, fiber laser and carbon dioxide laser.

7. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 1, wherein: Printing a self-heating conductive layer includes: based on the substrate layer, printing a conductive heating layer with a stretchable conductive paste according to a preset conductive pattern, and performing sintering and conductive treatment to complete the preparation of the conductive heating layer.

8. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 7, wherein: The printing material is a thermochromic material with a mass ratio of polydimethylsiloxane, cross-linking agent and thermochromic microcapsules of 10g:1g:0.5g respectively; using a multi-material conformal 3D printer, the thermotropic functional material is deposited on the substrate by preferentially forming the support skeleton and combining it with in-situ curing technology. After the program is completed, the preparation of the first layer of thermochromic information encryption layer is completed.

9. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 1, wherein: Printing the infrared information functional layer includes: using a stretchable conductive paste to print an infrared information pattern on the surface of the dielectric layer according to a preset pattern, and sintering and conducting the pattern after printing is completed.

10. The method for preparing a curved multi-layer encryption device integrating thermochromic and infrared thermal imaging according to claim 1, wherein: Printing the packaging protective layer includes: using degradable plastic as the packaging material to print the packaging layer, heating the entire sample to 125° C. for 40 minutes, curing the entire device, and completing the preparation of the encryption device after curing is completed.

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