A method for manufacturing a multilayer conductive structure, a conductive structure and an electronic device

Abstract

The present application relates to the field of microelectronics, and particularly relates to a preparation method of a multilayer conductive structure, a conductive structure and an electronic device. The preparation method of the multilayer conductive structure comprises the following steps: providing at least two silk fibroin films; preparing a conductive hole and a metal pattern layer on each of the at least two silk fibroin films to obtain at least two target silk fibroin films; and bonding the at least two target silk fibroin films according to a preset structure level to form a multilayer conductive structure. In the step of preparing the conductive hole on each of the silk fibroin films, a preset through hole is formed on the silk fibroin film, conductive ink is filled into the preset through hole, the conductive ink is a water solution of a polymer formed by silk fibroin and carbon nanotubes, and a first drying treatment is performed to form the conductive hole. In this way, the entire forming process is simple, and the formed conductive structure has better biocompatibility, mechanical properties and degradability.

Description

Technical Field

[0001] This invention relates to the field of microelectronics technology, and in particular to a method for preparing a multilayer conductive structure, the conductive structure, and an electronic device thereof. Background Technology

[0002] With the continuous advancement of materials science, microelectronics, and micro / nano fabrication technologies, the demand for higher-performance, smaller, safer, and environmentally sustainable electronic products is growing. This is particularly true in the fields of biomedicine and wearable devices, where the need for materials that are biocompatible, possess excellent mechanical properties, and are environmentally friendly is especially urgent.

[0003] Traditional conductive materials, such as metals and synthetic polymers, are widely used in electronic devices, but they often lack sufficient biocompatibility and biodegradability, limiting their application in flexible and wearable devices. Silk fibroin, as a natural protein, is considered an ideal candidate material for solving these problems due to its excellent biocompatibility, superior mechanical strength, and biodegradability.

[0004] However, how to achieve the application of silk fibroin in the electronic field while maintaining its biocompatibility and mechanical properties, especially how to prepare silk fibroin-based multilayer structures with excellent conductivity, remains a technical challenge. Summary of the Invention

[0005] To address the aforementioned technical problems, this application discloses a method for preparing a multilayer conductive structure, comprising:

[0006] Provide at least two silk fibroin membranes;

[0007] Conductive holes and metal patterned layers are fabricated on each of the at least two silk fibroin films to obtain at least two target silk fibroin films.

[0008] The at least two target silk fibroin membranes are bonded together according to a preset structural hierarchy to form a multilayer conductive structure;

[0009] The process of fabricating conductive pores on each of the silk fibroin membranes includes:

[0010] Pre-defined pores are formed on the silk fibroin membrane;

[0011] The predetermined through-hole is filled with conductive ink; the conductive ink is an aqueous solution of a polymer formed by silk fibroin and carbon nanotubes.

[0012] The first drying process is then performed to form the conductive holes.

[0013] Furthermore, forming predetermined pores on the silk fibroin membrane includes:

[0014] Two blocking components are provided;

[0015] A blocking element is placed on the upper and lower surfaces of the silk fibroin membrane to form an intermediate structure; the size of the blocking element is greater than or equal to the size of the silk fibroin membrane.

[0016] A pre-set through hole is formed on the intermediate structure using a laser punching process.

[0017] Furthermore, the conditions for the first drying process include:

[0018] The drying temperature is 40-50℃, and the drying time is 1-3 hours.

[0019] Furthermore, the diameter of the preset through hole is 0.05–0.2 mm;

[0020] The material of the blocking element includes polyvinyl alcohol.

[0021] Furthermore, a metal patterned layer is prepared on each of the silk fibroin films, including:

[0022] A mask pattern is formed on the silk fibroin membrane;

[0023] The metal pattern layer is formed by evaporating the mask pattern onto the silk fibroin film using electron beam evaporation technology, and then the mask pattern is removed.

[0024] Furthermore, a metal patterned layer is prepared on each of the silk fibroin films, including:

[0025] The conductive ink is applied to the silk fibroin film using screen printing technology.

[0026] A second drying process is then performed to form the metal pattern layer.

[0027] Furthermore, the step of bonding the at least two target silk fibroin membranes according to a predetermined structural hierarchy to form a multilayer conductive structure includes:

[0028] At least two of the target silk fibroin membranes were subjected to plasma cleaning treatment respectively;

[0029] The surfaces to be bonded in at least two of the target silk fibroin membranes are coated with silk fibroin liquid;

[0030] At least two of the target silk fibroin membranes are stacked and compressed according to a preset structural hierarchy to obtain an initial multilayer conductive structure.

[0031] The initial multilayer conductive structure is subjected to water vapor crosslinking and drying treatments in sequence to obtain the multilayer conductive structure.

[0032] Furthermore, the step of fabricating conductive holes and metal patterned layers on each of the at least two silk fibroin films to obtain at least two target silk fibroin films includes:

[0033] Conductive holes are prepared on each of the at least two silk fibroin films, and then a metal pattern layer is prepared on each of the silk fibroin films to obtain at least two target silk fibroin films; or, a metal pattern layer is prepared on each of the at least two silk fibroin films, and then a conductive hole is prepared on each of the silk fibroin films to obtain at least two target silk fibroin films.

[0034] In another aspect, this application also discloses a conductive structure, which is prepared using the above-described preparation method.

[0035] In another aspect, this application also discloses an electronic device comprising the aforementioned conductive structure.

[0036] This application provides a method for preparing a multilayer conductive structure. The method involves providing at least two silk fibroin films; fabricating conductive holes and a metal pattern layer on each of the at least two silk fibroin films to obtain at least two target silk fibroin films; bonding the at least two target silk fibroin films according to a predetermined structural hierarchy to form a multilayer conductive structure; specifically, fabricating conductive holes on each silk fibroin film involves forming predetermined through-holes on the silk fibroin film; filling the predetermined through-holes with conductive ink; the conductive ink is an aqueous solution of a polymer formed from silk fibroin and carbon nanotubes; and then performing a first drying treatment to form the conductive holes. This method simplifies the entire molding process and results in a conductive structure with better biocompatibility, mechanical properties, and biodegradability. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic flowchart illustrating a method for preparing a multilayer conductive structure exemplarily provided in this application.

[0039] Figure 2 This is a schematic diagram of the structure of a silk fibroin membrane with pre-set through holes, which is an example of this application.

[0040] Figure 3 This is a schematic diagram of the structure of a silk fibroin membrane with conductive holes, which is an example of this application.

[0041] Figure 4 This is a schematic diagram of the structure of a target silk fibroin membrane, which is an example of this application.

[0042] The following is supplementary explanation of the attached figures:

[0043] 1-Silk fibroin membrane; 11-First silk fibroin membrane; 12-Second silk fibroin membrane; 2-Preset through-hole; 3-Conductive hole; 4-Metal pattern layer. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0045] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. In the description of this application, it should be understood that the terms "upper," "lower," "top," "bottom," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein.

[0046] For the purposes of the detailed description below, it should be understood that the invention may take various alternative variations and sequences of steps unless expressly stated otherwise. Furthermore, except in any operational instance, or otherwise indicated, all figures representing the amounts of ingredients used, for example, in the specification and claims, should be understood to be modified in all cases by the term “about.” Therefore, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations varying with the desired performance to be obtained according to the invention. It is not at all an attempt to limit the application of the doctrine of equivalents to the scope of the claims; each numerical parameter should be interpreted at least according to the number of significant figures reported and by applying ordinary rounding techniques.

[0047] Although the numerical ranges and parameters illustrating the broad scope of the invention are approximate, the values ​​listed in the specific examples are reported as precisely as possible. However, any numerical value inherently contains some error that is necessarily caused by the standard deviation found in their respective test measurements.

[0048] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included. For example, a specified range from “1 to 10” should be considered to include any and all subranges between the minimum value 1 and the maximum value 10. Exemplary subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0049] Please see Figure 1 The diagram illustrates a process flow of an exemplary method for fabricating a multilayer conductive structure according to this application. Specifically, the method for fabricating this multilayer conductive structure may include:

[0050] S101: Provide at least two silk fibroin membranes.

[0051] In this embodiment, the silk fibroin membrane 1 can be obtained directly or prepared by the following method: first, prepare an aqueous solution of silk fibroin, form a wet silk fibroin membrane based on the aqueous solution, and then place the wet silk fibroin membrane in a vacuum water vapor environment to allow the silk fibroin molecules of the wet silk fibroin membrane to crosslink and form the silk fibroin membrane 1.

[0052] Specifically, the silk fibroin aqueous solution can be prepared through the following steps:

[0053] 1) Weigh out dry and clean silkworm cocoons and place them in a sodium carbonate solution for heating treatment to remove the sericin from the cocoons, thereby completing degumming and forming silk.

[0054] For example, silkworm cocoons can be cut into small pieces and placed in a sodium carbonate solution, then heated and stirred. The silkworm cocoons are those from which the pupae have been removed.

[0055] The concentration of the sodium carbonate solution is 0.1-3 g / L, and the mass ratio of the silkworm cocoon to the volume of the sodium carbonate solution is (5:2), in g / L.

[0056] The sodium carbonate solution can be heated by an electric furnace or a pressure cooker, with a heating temperature of 60-100°C, a heating pressure of 0.5-1 MPa, and a heating time of 1 second to 1000 hours.

[0057] 2) Place the silk in deionized water and wash it multiple times.

[0058] The silkworm silk is washed by stirring or soaking. The stirring method is mechanical stirring or magnetic stirring, and the magnetic stirring speed is 1 to 2000 r / min. In a single washing process, the mass ratio of the silkworm silk to the ultrapure water is 1:20 to 1:50, in g / L, and the time is 60s to 5h. After each washing, the silkworm silk is taken out and squeezed dry, and the washing is repeated 1 to 50 times.

[0059] 3) Dry the washed silk, and mix the dried silk with the lithium salt aqueous solution. Keep it warm for a period of time to obtain the silk fibroin lithium salt aqueous solution.

[0060] An exemplary drying method is natural air drying or heated ventilation drying, wherein the temperature of heated ventilation drying is 50-70°C and the drying time is 1-20 hours.

[0061] The exemplary lithium salt aqueous solution is a lithium thiocyanate solution or a lithium bromide solution, the concentration of the lithium salt aqueous solution is 0.01-2 g / ml, the mass ratio of the dried silk to the volume of the lithium salt aqueous solution is (1-100):100, g / ml; the heat preservation temperature is 30-80℃, and the heat preservation time is 0.5-5h.

[0062] Lithium salt aqueous solution can be used to break the hydrogen bond network in silk fibers, thereby dissolving silk fibroin into a silk fibroin solution to generate new materials.

[0063] 4) Pour the silk fibroin lithium salt aqueous solution into a dialysis bag and dialyze it in ultrapure water.

[0064] For example, the dialysis method is either static dialysis or magnetically stirred dialysis. Optionally, the dialysis bag has a size of 10–1,000,000 Da, and the dialysis method is either static dialysis or magnetically stirred dialysis. The stirring speed for magnetically stirred dialysis is 1–2000 r / min, the time interval for water exchange during dialysis is 0.1–100 h, and the volume of ultrapure water required for each dialysis is 1 mL–1000 L. After dialysis, dissolved lithium bromide can be removed to prevent subsequent ion residues from causing harm to humans.

[0065] For example, the stirring speed is 60-300 r / min, and the time interval for water exchange during dialysis is 1-24 h.

[0066] 5) Centrifuge the dialyzed silk fibroin lithium salt aqueous solution and collect the supernatant after centrifugation to obtain the silk fibroin aqueous solution.

[0067] For example, the centrifugation process is carried out at a speed of 10–20000 r / min, for a time of 6 s–2 h, and at a temperature of -3–5 °C. The concentration of the silk fibroin aqueous solution 1 is 0.05–0.25 g / ml.

[0068] A method for forming a silk fibroin wet film includes: coating the silk fibroin aqueous solution onto a flat mold, and allowing it to stand under preset temperature and humidity conditions to form the silk fibroin wet film. Optionally, the silk fibroin aqueous solution can be transferred into the flat mold using a pipette, then the solution can be spread evenly to achieve a preset thickness, and small air bubbles on the solution surface can be removed with a dropper. The plate coated with the silk fibroin aqueous solution can then be allowed to dry naturally under preset temperature and humidity conditions to form a film. Optionally, the volume of the pipette is 0.1–20 mL; the area of ​​the flat mold is 0.01–100 cm².

[0069] For example, the preset temperature and humidity conditions include: a temperature range of 15 to 25°C; a humidity range of 38 to 39% RH; and a resting time of 1 to 100 hours.

[0070] For example, the thickness of the silk fibroin aqueous solution coated on the flat mold ranges from 0.1 to 10 mm.

[0071] For example, the flat plate mold can be one or a combination of acrylic sheet, polystyrene sheet, polypropylene sheet and metal sheet.

[0072] Next, the uneven edges of the silk fibroin wet film need to be trimmed before placing it on a flat mold.

[0073] A specific embodiment of placing the silk fibroin wet film in a vacuum steam environment to crosslink the silk fibroin molecules and form silk fibroin film 1 may include: placing the silk fibroin wet film in a vacuum vessel containing water and turning on the vacuum vessel; the pressure of the vacuum vessel is -0.01 to -0.1 MPa. Optionally, the silk fibroin wet film is placed in the vacuum vessel 4 for crosslinking for 1 to 50 hours, and after crosslinking is completed, insoluble silk fibroin film 1 can be obtained.

[0074] S103: Conductive holes and metal pattern layers are prepared on each of the at least two silk fibroin films to obtain at least two target silk fibroin films.

[0075] In this embodiment of the application, the target silk fibroin membrane 1 can specifically be as follows: Figure 3 The structures of the two silk fibroin films 1 shown are assumed to be two silk fibroin films 1 provided in step S101 of this application embodiment, referred to as the first silk fibroin film 11 and the second silk fibroin film 12, respectively. By sequentially fabricating conductive holes 3 and metal pattern layers 4 in the first silk fibroin film 11 and the second silk fibroin film 12, the following can be obtained: Figure 3 To achieve electrical connection between the metal pattern layer 4 on the two target silk fibroin films 1, the positions of the conductive holes 3 on the two silk fibroin films 1 must correspond to form a conductive path. Specifically, the target silk fibroin film 1 corresponding to the first silk fibroin film 11 can be used as the bottom layer, and the second silk fibroin film 12 can be used as the top layer. Then, after subsequent stacking, the second silk fibroin film 12 is located on the first silk fibroin film 11.

[0076] In one feasible embodiment, step S102 may specifically include: preparing conductive holes 3 on each of the at least two silk fibroin membranes 1, to obtain... Figure 4 The structure shown is followed by the fabrication of a metal pattern layer 4 on each of the silk fibroin films 1, resulting in at least two target silk fibroin films 1. This means that conductive holes 3 can be formed on the silk fibroin films 1 first, followed by the formation of the metal pattern layer 4. In another feasible embodiment, step S102 may specifically include fabricating a metal pattern layer 4 on each of the at least two silk fibroin films 1, and then forming conductive holes 3 on each silk fibroin film 1, resulting in at least two target silk fibroin films 1. That is, the metal pattern layer 4 can be formed on the silk fibroin films 1 first, followed by the formation of the conductive holes 3. No limitations are imposed here.

[0077] The process of preparing conductive holes 3 on each of the silk fibroin membranes 1 includes: forming a pre-set through hole 2 on the silk fibroin membrane 1; filling the pre-set through hole 2 with conductive ink; the conductive ink being an aqueous solution of a polymer formed from silk fibroin and carbon nanotubes; and then performing a first drying treatment to form the conductive holes 3.

[0078] In this embodiment of the application, the method for preparing conductive ink may specifically include:

[0079] A silk fibroin aqueous solution and a carbon nanotube aqueous solution are mixed in a preset ratio, wherein the mass ratio of silk fibroin to carbon nanotubes is 0.5 to 0.9. The solution after mixing the silk fibroin aqueous solution and the carbon nanotube aqueous solution is heated to a preset temperature and subjected to low-speed stirring to obtain conductive ink.

[0080] The silk fibroin aqueous solution can be prepared based on steps 1)-5) above. Optionally, the mass fraction of the silk fibroin aqueous solution is 1.5% to 3.5%. For example, the mass fraction of the silk fibroin aqueous solution can be 1.5%, 2%, 2.5%, 3%, or 3.5%.

[0081] The carbon nanotube aqueous solution can be obtained through the following steps: providing a predetermined amount of carbon nanotubes; adding the carbon nanotubes to deionized water to obtain a carbon nanotube mixture; subjecting the carbon nanotube mixture to ultrasonic treatment, stirring treatment and centrifugation treatment in sequence to obtain an initial carbon nanotube aqueous solution; and diluting the initial carbon nanotube aqueous solution to obtain a carbon nanotube aqueous solution.

[0082] In this embodiment, a predetermined amount of carbon nanotubes is slowly added to deionized water to obtain a carbon nanotube mixture. The carbon nanotube mixture is then subjected to ultrasonic treatment, stirring, and centrifugation sequentially to obtain an initial aqueous solution with uniformly dispersed carbon nanotubes. To obtain the initial aqueous solution, the carbon nanotube mixture is first ultrasonically treated using an ultrasonic processor to break up carbon nanotube aggregates and improve their dispersibility; then, a magnetic stirrer is used to stir the mixture to enhance the dispersion effect; finally, the mixture is centrifuged at high speed to remove undispersed large particles or aggregates. The supernatant of the centrifuged solution is the initial aqueous solution with carbon nanotubes.

[0083] Optionally, the ultrasonic treatment time is 15 to 45 minutes. For example, the ultrasonic treatment time can be 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, or 45 minutes.

[0084] Optionally, the stirring treatment time is 10 to 14 hours. For example, the stirring treatment time can be 10 hours, 11 hours, 12 hours, 13 hours, or 14 hours.

[0085] Optionally, the centrifugation time is 15 to 30 minutes. For example, the centrifugation time can be 15 minutes, 20 minutes, 25 minutes, or 30 minutes.

[0086] In this embodiment, the ultrasonic treatment time is 15 minutes. The stirring treatment time is 12 hours. The centrifugation treatment time is 22 minutes.

[0087] In this embodiment, the initial carbon nanotube aqueous solution is diluted to obtain a carbon nanotube aqueous solution. The mass fraction of the carbon nanotube aqueous solution needs to be controlled within a certain range so that the carbon nanotube aqueous solution can be fully mixed with the silk fibroin aqueous solution, while fully utilizing the conductivity of the carbon nanotubes. If the mass fraction of the carbon nanotube aqueous solution is too high, there will be insufficient solvent to promote the recombination of carbon nanotubes in the silk fibroin molecular network. If the mass fraction of the carbon nanotube aqueous solution is too low, the carbon nanotube content in the mixed solution formed by the mixture of silk fibroin aqueous solution and carbon nanotube aqueous solution will be too low, resulting in poor conductivity of the mixed solution.

[0088] In this embodiment, the mass fraction of the carbon nanotube aqueous solution needs to be precisely controlled. The mass fraction of the initial carbon nanotube aqueous solution and the mass fraction of the carbon nanotube mixture used to prepare the initial carbon nanotube aqueous solution need to be controlled within a certain range. However, it is necessary to ensure that the mass fractions of both the initial carbon nanotube aqueous solution and the carbon nanotube mixture are greater than the mass fraction of the carbon nanotube aqueous solution, so as not to affect the preparation of the carbon nanotube aqueous solution. Since centrifugation discards some carbon nanotubes during the preparation of the initial carbon nanotube aqueous solution using the carbon nanotube mixture, the mass fraction of the initial carbon nanotube aqueous solution cannot be equated to the mass fraction of the carbon nanotube mixture. Therefore, a moisture balance can be used to determine the mass fraction of the initial carbon nanotube aqueous solution and prepare the carbon nanotube aqueous solution with the required mass fraction.

[0089] Optionally, the mass fraction of the carbon nanotube mixture is 2.5% to 7.5%. For example, the mass fraction of the carbon nanotube mixture can be 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, or 7.5%.

[0090] Optionally, the mass fraction of the carbon nanotube aqueous solution is 1% to 3%. For example, the mass fraction of the carbon nanotube aqueous solution can be 1%, 1.5%, 2%, 2.5%, or 3%.

[0091] Optionally, the mass fraction of the carbon nanotube aqueous solution is 1%. Optionally, the mass fraction of the carbon nanotube aqueous solution is 2%. Optionally, the mass fraction of the carbon nanotube aqueous solution is 3%.

[0092] In this embodiment, the carbon nanotubes are multi-walled carbon nanotubes. Multi-walled carbon nanotubes are simple to prepare, low in cost, and suitable for mass production. Moreover, multi-walled carbon nanotubes have a relatively large diameter, making it easier to form a stable conductive network during the dispersion process.

[0093] In one feasible implementation, carbon nanotubes can also be single-walled carbon nanotubes. Single-walled carbon nanotubes can provide higher conductivity, but their preparation cost is higher and the dispersion is more difficult to prepare.

[0094] In one feasible implementation, taking into account both conductivity and manufacturing cost, carbon nanotubes can be a mixture of single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0095] In this embodiment, a silk fibroin aqueous solution and a carbon nanotube aqueous solution are first mixed in a preset ratio. The resulting solution is then heated to a preset temperature and subjected to low-speed stirring to obtain conductive ink. This process uses low-speed stirring to ensure thorough mixing of the silk fibroin and carbon nanotube aqueous solutions. Vigorous stirring should be avoided to prevent the silk fibroin from cross-linking and forming a gel.

[0096] In this embodiment, when the silk fibroin aqueous solution and the carbon nanotube aqueous solution are first mixed together, the carbon nanotubes are not well dispersed in the silk fibroin solution, and the mixed solution exhibits obvious stratification. After low-speed stirring, the carbon nanotubes gradually disperse in the silk fibroin solution and eventually form a uniform conductive ink. In the conductive ink, amino acid residues in the silk fibroin (such as hydroxyl, carboxyl, and amino groups) can form hydrogen bonds with functional groups (such as carboxyl and hydroxyl groups) on the surface of the carbon nanotubes. Moreover, the functional groups of the silk fibroin may undergo cross-linking reactions with the functional groups in the carbon nanotubes.

[0097] In this embodiment, silk fibroin aqueous solution and carbon nanotube aqueous solution are mixed according to a preset ratio, requiring the mass ratio of silk fibroin to carbon nanotubes in the conductive ink to be within a certain range. Different mass ratios of silk fibroin and carbon nanotubes will result in different conductivity and biocompatibility of the conductive ink. If the mass ratio of silk fibroin to carbon nanotubes is lower than the preset ratio, the content of silk fibroin is too low and the content of carbon nanotubes is too high, resulting in poor biocompatibility of the conductive ink. If the mass ratio of silk fibroin to carbon nanotubes is higher than the preset ratio, the content of silk fibroin is too high and the content of carbon nanotubes is too low, making it difficult for the silk fibroin aqueous solution and carbon nanotube aqueous solution to mix fully, and easily causing them to mix and form a gel-like substance, resulting in poor conductivity of the conductive ink formed by the silk fibroin aqueous solution and carbon nanotube aqueous solution.

[0098] In one feasible implementation, the preset ratio satisfies that the mass ratio of silk fibroin to carbon nanotubes is 0.5 to 0.9, that is, the mass ratio of silk fibroin to carbon nanotubes in the silk fibroin aqueous solution and the carbon nanotube aqueous solution used to prepare the conductive ink needs to be 0.5 to 0.9. For example, the mass ratio of silk fibroin to carbon nanotubes can be 0.5, 0.6, 0.7, 0.8, or 0.9.

[0099] In one feasible implementation, the preset temperature is 32-42°C. For example, the preset temperature can be 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, or 42°C.

[0100] In one feasible implementation, the low-speed stirring treatment time is 10 to 20 minutes. For example, the low-speed stirring treatment time can be 10 minutes, 15 minutes, or 20 minutes.

[0101] In one feasible implementation, the pH value of the solution obtained by mixing the silk fibroin aqueous solution and the carbon nanotube aqueous solution can also be adjusted to meet different application requirements. The charge state of silk fibroin depends on the pH value of the solution. Near the isoelectric point (pH approximately 4.5), the net charge of silk fibroin is zero, and its solubility is at its lowest. Under acidic conditions, silk fibroin is positively charged; under alkaline conditions, it is negatively charged. These charge changes affect the electrostatic interaction between silk fibroin and carbon nanotubes, thereby affecting the stability and conductivity of the mixed solution.

[0102] In this embodiment, a 2.5% (w / w) aqueous solution of silk fibroin and a 2% (w / w) aqueous solution of carbon nanotubes were selected. Following a standard mass ratio of 0.7 for silk fibroin and carbon nanotubes, appropriate amounts of the two aqueous solutions were mixed. The mixture was heated to 37°C and stirred at low speed for 20 minutes to obtain the conductive ink. Notably, the pH of the mixture was not adjusted; the mixture of silk fibroin and carbon nanotube aqueous solutions was a neutral solution.

[0103] In one feasible embodiment, forming a predetermined through-hole 2 on the silk fibroin membrane 1 includes: providing two blocking members; placing one blocking member on the upper and lower surfaces of the silk fibroin membrane 1 respectively to form an intermediate structure; the size of the blocking member is greater than or equal to the size of the silk fibroin membrane 1; and forming the predetermined through-hole 2 on the intermediate structure using a laser punching process to obtain the desired result. Figure 2 The structure shown.

[0104] In this embodiment, the material of the blocking member includes polyvinyl alcohol, which can also be a material with similar properties to the silk fibroin membrane 1, that is, it can soften when it comes into contact with water, has a certain degree of stretchability, but does not stick to the silk fibroin membrane 1, so that the blocking member can be removed from the target silk fibroin membrane 1 after the filling is completed.

[0105] In one feasible embodiment, the conditions for the first drying process include: a drying temperature of 40-50°C and a drying time of 1-3 hours. Room temperature drying can also be used, but the time is longer, requiring at least one day.

[0106] In one feasible embodiment, the diameter of the preset through hole 2 is 0.05 to 0.2 mm.

[0107] In the embodiments of this application, the process parameters of the laser punching process may include: punching speed of 600-750 mm / s; frequency of 45-55 kHz; pulse width of 0.5-1.5 μs; and laser scanning density of 0.015-0.03 mm.

[0108] In this embodiment, the method for preparing the metal pattern layer 4 on the silk fibroin film 1 can include two approaches. One approach is to use an electron beam evaporation process, specifically, forming a mask pattern on the silk fibroin film 1; then using electron beam evaporation technology to evaporate the metal pattern onto the silk fibroin film 1 through the mask pattern to form the metal pattern layer 4, and finally removing the mask pattern. The other approach is to use a screen printing process, specifically, using screen printing technology to apply the conductive ink onto the silk fibroin film 1; followed by a second drying process to form the metal pattern layer 4. Optionally, the conditions for the second drying process include: a drying temperature of 40–50°C and a drying time of 1–3 hours.

[0109] In this embodiment, the conductive material filling the pre-set through-hole 2 is conductive ink. Since the conductive ink is prepared from a silk fibroin aqueous solution and carbon nanotubes, the amino acid residues (such as hydroxyl, carboxyl, and amino groups) in the silk fibroin film can form hydrogen bonds with the functional groups (such as carboxyl and hydroxyl groups) on the surface of the carbon nanotubes. As a result, the black conductive layer formed by the conductive ink and the base layer formed by the silk fibroin film have good adhesion reliability and will not detach. Similarly, when the metal pattern layer 4 is formed by conductive ink, it also has the above-mentioned effect, enabling the entire multilayer conductive structure to not only realize the design of complex circuits, but also to have better biocompatibility, mechanical properties, and biodegradability.

[0110] S105: The at least two target silk fibroin membranes are bonded together according to a preset structural hierarchy to form a multilayer conductive structure;

[0111] In a feasible embodiment, step S103 may specifically include: performing plasma cleaning treatment on at least two of the target silk fibroin membranes 1 respectively; coating the surfaces to be bonded in at least two of the target silk fibroin membranes 1 with silk fibroin liquid respectively; stacking and pressing at least two of the target silk fibroin membranes 1 according to a preset structural hierarchy to obtain an initial multilayer conductive structure; and sequentially performing water vapor crosslinking and drying treatment on the initial multilayer conductive structure to obtain the multilayer conductive structure.

[0112] Optionally, the parameters for the above plasma cleaning treatment are: power of 35–45 W; time of 25–35 s. Optionally, for N target silk fibroin membranes 1, silk fibroin solution can be coated only on the upper / lower surfaces of N-1 membranes, where N is an integer greater than or equal to 2. Continuing with the above example, for such... Figure 3 The two target silk fibroin membranes 1 shown can be prepared by coating only the upper surface of the first silk fibroin membrane 11 with silk fibroin liquid, and then covering the upper surface of the first silk fibroin membrane 11 with the lower surface of the second silk fibroin membrane 12. The two target silk fibroin membranes 1 can be pressed together using a silicone pad, and then placed in a vacuum vessel containing water for water vapor crosslinking treatment. The specific parameters for water vapor crosslinking treatment can be found in the above description of the preparation of silk fibroin membranes 1.

[0113] This application provides a method for preparing a multilayer conductive structure. By drilling holes and filling conductive ink on each of the multiple silk fibroin films 1, conductive holes 3 are formed and a metal pattern layer 4 is formed, resulting in multiple target silk fibroin films 1. Then, according to a preset stacking order and the alignment reference of the conductive holes 3 of the upper and lower target silk fibroin films 1, the multiple target silk fibroin films 1 are bonded together to obtain a multilayer conductive structure.

[0114] Silk fibroin is a natural protein with good biocompatibility and biodegradability. In the medical and bioelectronic fields, silk fibroin can be used as a substrate material to fabricate conductive structures compatible with human tissues, which can be used in biosensors, implantable medical devices, and other applications.

[0115] Silk fibroin possesses excellent mechanical strength and elasticity. This enables silk fibroin-based multilayer conductive structures to not only withstand certain physical pressures but also maintain their function when bent and stretched, making them suitable for wearable devices and flexible electronics.

[0116] This method not only features a simple preparation process, but also, because the multilayer conductive structure prepared based on the aforementioned silk fibroin membrane 1 possesses advantages such as good biocompatibility, good mechanical properties, and biodegradability, the conductive ink filled within the conductive pores 3 is an aqueous solution of a polymer formed from silk fibroin and carbon nanotubes, resulting in high overall conductivity reliability. This demonstrates significant application potential in the fields of biomedicine, environmental protection, and wearable devices. The development of this technology will help drive traditional electronics manufacturing towards a greener and more sustainable direction.

[0117] In another aspect, this application also discloses a conductive structure, which is prepared using the above-described preparation method.

[0118] This application also discloses an electronic device that includes the aforementioned conductive structure. Specifically, this electronic device can be an electronic device used in the fields of biomedicine and wearable devices, such as a biosensor or implantable device.

[0119] The above description is only an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method of making a multilayer conductive structure, characterized by, include: Provide at least two silk fibroin membranes; Conductive holes and metal patterned layers are fabricated on each of the at least two silk fibroin films to obtain at least two target silk fibroin films. The at least two target silk fibroin membranes are bonded together according to a preset structural hierarchy to form a multilayer conductive structure; The process of fabricating conductive pores on each of the silk fibroin membranes includes: Pre-defined pores are formed on the silk fibroin membrane; The predetermined through-hole is filled with conductive ink; the conductive ink is an aqueous solution of a polymer formed by silk fibroin and carbon nanotubes. The first drying process is then performed to form the conductive holes.

2. The production method according to claim 1, characterized by, The process of forming predetermined pores on the silk fibroin membrane includes: Two blocking components are provided; A blocking element is placed on the upper and lower surfaces of the silk fibroin membrane to form an intermediate structure; the size of the blocking element is greater than or equal to the size of the silk fibroin membrane. A pre-set through hole is formed on the intermediate structure using a laser punching process.

3. The preparation method according to claim 1, characterized in that, The conditions for the first drying process include: The drying temperature is 40-50℃, and the drying time is 1-3 hours.

4. The preparation method according to claim 2, characterized in that, The diameter of the preset through hole is 0.05 to 0.2 mm; The material of the blocking element includes polyvinyl alcohol.

5. The preparation method according to claim 1, characterized in that, Fabricating a metal patterned layer on each of the silk fibroin films includes: A mask pattern is formed on the silk fibroin membrane; The metal pattern layer is formed by evaporating the mask pattern onto the silk fibroin film using electron beam evaporation technology, and then the mask pattern is removed.

6. The preparation method according to claim 1, characterized in that, Fabricating a metal patterned layer on each of the silk fibroin films includes: The conductive ink is applied to the silk fibroin film using screen printing technology. A second drying process is then performed to form the metal pattern layer.

7. The preparation method according to claim 1, characterized in that, The step of bonding the at least two target silk fibroin membranes according to a preset structural hierarchy to form a multilayer conductive structure includes: At least two of the target silk fibroin membranes were subjected to plasma cleaning treatment respectively; The surfaces to be bonded in at least two of the target silk fibroin membranes are coated with silk fibroin liquid; At least two of the target silk fibroin membranes are stacked and compressed according to a preset structural hierarchy to obtain an initial multilayer conductive structure. The initial multilayer conductive structure is subjected to water vapor crosslinking and drying treatments in sequence to obtain the multilayer conductive structure.

8. The preparation method according to claim 1, characterized in that, The process involves fabricating conductive holes and metal patterned layers on each of the at least two silk fibroin films to obtain at least two target silk fibroin films, including: Conductive holes are prepared on each of the at least two silk fibroin films, and then a metal pattern layer is prepared on each of the silk fibroin films to obtain at least two target silk fibroin films; or, a metal pattern layer is prepared on each of the at least two silk fibroin films, and then a conductive hole is prepared on each of the silk fibroin films to obtain at least two target silk fibroin films.

9. A conductive structure, characterized in that, It is prepared using the preparation method described in any one of claims 1-8.

10. An electronic device, characterized in that, Includes the conductive structure as described in claim 9.

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