Composite material and rapid preparation method

Abstract

The invention relates to the technical field of biological conduction, in particular to a composite material and a rapid preparation method. The invention provides a bioelectronics-oriented novel flexible conductive composite material. The bioelectronics-oriented novel flexible conductive composite material is prepared by performing illumination molding on a mixed system. The preparation method comprises the following steps: dissolving polyether F127-diacrylate serving as an elastic network skeleton in a conductive polymer solution and uniformly doping a conductive polymer to prepare semi-interpenetrating double-network hydrogel; afterwards, excessive small molecules are removed through mild glacial acetic acid treatment, and chain segments are induced to be rearranged. The biological flexible conductive material prepared by the invention has excellent conductivity, mechanical property and biocompatibility, and a biological flexible electrode with good performance can be obtained by combining a 3D printing technology. According to the flexible electrode, the bottlenecks that an existing flexible electrode is low in conductivity, complex in packaging and limited in large-size printing are improved from a material system to a manufacturing process, and a universal and efficient new scheme is provided for implantable soft bioelectronics.

Description

[0001] Priority Application This application claims priority to Chinese Patent Application No. 2024116728440, filed November 21, 2024, entitled “A Composite Material and Rapid Preparation Method,” which is incorporated by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of bio-conducting technology, specifically to a composite material and rapid preparation method. BACKGROUND

[0003] The integration of biological technology and information technology is a key research direction for the development of life-nonlife hybrid systems in the future. One of the main obstacles to its development is the lack of an effective information exchange interface. Electrodes, as electronic components, can establish a direct information path between biological entities and external devices, making them a key component in the integration of biological technology and information technology. However, traditional electrodes are mostly rigid with high modulus, which can cause mechanical damage, trigger immune responses, and lead to inflammation of biological tissues, resulting in scar tissue around the electrodes. In addition, rigid electrodes usually have high impedance when in contact with biological tissues, significantly affecting signal transmission quality. The poor mobility of rigid electrodes also makes it difficult for them to adapt to dynamic biological environments, limiting their practical applications.

[0004] Flexible electrodes are increasingly important in the field of biomedical engineering. As a key component in the integration of biological technology and information technology, flexible electrodes can better adapt to the complex shape and dynamic movement of biological tissues, thereby improving the comfort and biocompatibility of biomedical electronic devices. In addition, the application of flexible electrodes in implantable medical devices is of great significance. Traditional rigid electrodes may cause tissue damage during implantation, while flexible electrodes can greatly reduce mechanical damage due to their softness and can make closer contact with biological tissues, thereby improving signal transmission stability and accuracy and enhancing biological safety. For example, in devices such as brain-computer interfaces and cardiac pacemakers, the use of flexible electrodes can significantly reduce surgical risks and postoperative complications. In addition, with the increasing demand for health monitoring, wearable devices have become an indispensable part of daily life, and flexible electrodes also show great potential in wearable devices. Flexible electrodes, due to their light weight, softness, and high conductivity, are ideal sensor materials for wearable devices, which can be used to monitor physiological parameters such as heart rate, blood oxygen saturation, and electromyography signals, thereby achieving real-time health monitoring and management.

[0005] Although flexible electrodes made of conductive polymers, carbon nanomaterials and metal nanomaterials have been widely used in various electronic devices, these devices still face challenges such as limited biocompatibility, poor bioadhesion, unstable electrical performance under dynamic deformation, and complex manufacturing process, which limit the application of flexible electrodes.

[0006] In recent years, 3D printing has become a disruptive manufacturing technology, providing unique advantages in the personalized customization of complex structures. It also provides a reliable tool for the manufacture of flexible electrodes. In the process of 3D printing flexible electrodes, materials are crucial because their performance can significantly affect the electrical performance, mechanical performance and biocompatibility of the electrodes. However, the lack of suitable material systems limits the development of 3D printed flexible electrodes. In addition, flexible electrodes will be repeatedly bent and stretched during use, which can cause material fatigue and performance degradation. Therefore, it is a key challenge to improve the flexibility, stability, durability and conductivity of flexible electrodes while maintaining biocompatibility. SUMMARY

[0007] The purpose of the present application is to provide a composite material (which can also be understood as "a biocompatible flexible conductive material" and "a conductive hydrogel") and a rapid preparation method, which partially solves or alleviates the above-mentioned deficiencies in the prior art, and can comprehensively improve the conductivity and stretchability of the composite material that can be used to print flexible electrodes (such as metal-free flexible electrodes).

[0008] In order to solve the above-mentioned technical problems, the present application specifically adopts the following technical solutions: The first aspect of the present application is to provide a biocompatible flexible conductive material, which is prepared by light molding of a mixed system (which can also be understood as a "composite system") and has a predetermined shape. In some embodiments, the mixed system is prepared by dissolving polyether F127-diacrylate in a conductive polymer solution. In some embodiments, the degree of substitution of the polyether F127-diacrylate is ≥ 95%. In some embodiments, the concentration of the polyether F127-diacrylate (F127DA) in the mixed system is about 5-20% (w / v). See Figure 5 The conductive hydrogel in this range can be well shaped and has a relatively clear outline. Preferably, the mixed system with a concentration of F127DA of about 10-20% (w / v) is used to prepare the conductive hydrogel. Preferably, the mixed system with a concentration of F127DA of about 15-20% (w / v) is used to prepare the conductive hydrogel. The hydrogel in this range has a very clear outline, for example, in some embodiments, when the shape of the conductive hydrogel / flexible electrode is required to be high (such as the need to design customized special-shaped conductive structures), F127DA in this concentration range can be used.

[0009] Alternatively, in other embodiments, different concentration ranges such as about 5-10% (w / v), 10-15% (w / v), 15-20% (w / v), etc. can be used to prepare the bio-flexible conductive material in combination with the actual conductive requirement.

[0010] In some embodiments, the conductive polymer can be poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS). In other embodiments, PEDOT:PSS can be replaced by PBFDO (benzodifuranedione) when applied to scenarios with different conductive or stretch performance requirements. In other embodiments, PEDOT:PSS can be replaced by PPY (poly pyrrole) when applied to scenarios with different conductive or stretch performance requirements. In other embodiments, PEDOT:PSS can be replaced by a polymer system with 3,4-ethylenedioxythiophene (EDOT) as a monomer when applied to scenarios with different conductive or stretch performance requirements. In some embodiments, the solvent of the conductive polymer solution can be water.

[0011] In some embodiments, in the final formed mixed system, the concentration of PEDOT:PSS does not exceed 1.5% (w / v), and preferably, its concentration range is about 0.5%-1.5% (w / v). For example, in different preparation environments, or under different conductive and stretch performance preparation conditions, its concentration range can optionally include one or more of the following ranges or point values: about 0.5% (w / v), 0.6% (w / v), 0.7% (w / v), 0.8% (w / v), 0.9% (w / v), 1.0% (w / v), 1.1% (w / v), 1.2% (w / v), 1.3% (w / v), 1.4% (w / v), 1.5% (w / v), 0.5%-0.7% (w / v), 0.9%-1.1% (w / v), 1.1%-1.3% (w / v), 1.3%-1.5% (w / v). In some embodiments, the concentration ratio of the polyether F127-diacrylate to the conductive polymer in the mixed system is 10:1.

[0012] In some embodiments, the photo-shaping includes photo-shaping techniques based on light curing or photo-shaping techniques based on photolithography. In some embodiments, the method of light curing can be 3D printing, such as DLP-based 3D printing, laser-based 3D printing. In some embodiments, the hybrid system further includes a photo-initiator. In some embodiments, the photo-initiator can be lithium phenyl-2,4,6-trimethylbenzoyl phosphinate. Preferably, the photo-initiator has a concentration of about 0.5%-10% (w / v) in the hybrid system. In some embodiments, the photo-initiator has a concentration of about 0.5%-2% (w / v) in the hybrid system. Of course, in other embodiments, the type of photo-initiator includes but is not limited to the following types: 1173 photo-initiator: 2-hydroxy-2-methyl-1-phenylpropanone; 184 photo-initiator: 1-hydroxycyclohexyl phenyl ketone; 907 photo-initiator: 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]-1-propanone; TPO photo-initiator: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; TPO-L photo-initiator: 2,4,6-trimethylbenzoyl ethyl phenyl phosphinate; IHT-PI910 photo-initiator: 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]-1-butanone; 659 photo-initiator: 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone; photo-initiator MBF: methyl benzoylformate.

[0013] In some embodiments, the bio-flexible conductive material can be a two-dimensional structure (e.g., linear, sheet-like) or a three-dimensional (solid) structure (e.g., block-like (which can be needle-like, tube-like, strip-like)). In some embodiments, the bio-flexible conductive material is further subjected to acid treatment. In some embodiments, the acid used in the acid treatment step is glacial acetic acid. In some embodiments, the acid treatment time is ≥ 4 hours. In some embodiments, the bio-flexible conductive material further includes one or more patch layers. In some embodiments, the bio-flexible conductive material further includes an active functional ingredient, such as a drug, a cytokine.

[0014] In a second aspect, the present application also provides a bio-flexible electrode prepared using the bio-flexible conductive material according to any one of the embodiments.

[0015] In a third aspect, the present application also provides a bio-flexible electrode patch, comprising: a first patch layer and a second patch layer, and a bio-flexible electrode disposed between the first patch layer and the second patch layer, wherein the bio-flexible electrode is prepared using the bio-flexible conductive material according to any one of the embodiments.

[0016] It should be noted that the biocompatible flexible electrode patch provided by the present application can be a double-layer or multi-layer patch layer, for example, it can further sequentially include: a first patch layer, a second patch layer and a third patch layer, and at least one biocompatible flexible electrode (and preferably one or more biocompatible flexible electrodes) can be arranged between adjacent two patch layers, and the number of patch layers is not limited by the present application.

[0017] In some embodiments, the first patch layer and / or the second patch layer is prepared by using a gel. In some embodiments, the gel includes polyether F127-diacrylate. In some embodiments, the concentration of the polyether F127-diacrylate (F127DA) is about 5-20% (w / v).

[0018] In a fourth aspect, the present application further provides a use of the biocompatible flexible conductive material described above in the preparation of a biotic electric interface (BEI).

[0019] In some embodiments, the biotic electric interface includes but is not limited to one or more of the following: a prosthesis, a neural interface (such as a brain-computer interface, such as a brain cortex interface, etc.), a flexible biotic interface electronic product, etc. For example, the biotic electric interface can refer to a heart pacemaker interface, etc. In some embodiments, the biotic electric interface includes one or more of an electroencephalogram interface, an electromyogram interface, and an electrocardiogram interface.

[0020] In a fifth aspect, the present application further provides a use of the biocompatible flexible conductive material described above in the preparation of a biocompatible conductive material. In some embodiments, the biocompatible conductive material can be attached to the skin, wound, organ or tissue of a living being, etc. to complete the collection and transmission of bioelectric signals (such as electrical stimulation). In some embodiments, the biocompatible conductive material is a metal-free flexible electrode. In some embodiments, the biocompatible conductive material is used for electrical stimulation.

[0021] In a sixth aspect, the present application further provides a use of the biocompatible flexible conductive material described above in the preparation of a biocompatible flexible electrode patch. In some embodiments, the biocompatible flexible electrode patch is prepared by DLP-based 3D printing.

[0022] In a seventh aspect, the present application also provides a method for preparing a bioflexible electrode patch, comprising the steps of: S101, providing a layer of liquid hydrogel, and using a light curing device to cure the liquid hydrogel using a first exposure intensity for a first duration of time to form a first patch layer; S102, covering a layer of liquid composite material on the first patch layer, and using a light curing device to segmentally cure the liquid composite material using a second exposure intensity for a second duration of time to form a corresponding printed pattern on the first patch layer, the printed pattern being composed of at least one electrode, and the width of the input end of the electrode being greater than the main body width of the electrode; S103, continuously covering a layer of liquid hydrogel on the printed pattern, and using a light curing device to cure the liquid hydrogel using a third exposure intensity for a third duration of time; wherein the third duration of time is less than the first duration of time.

[0023] In some embodiments, the composite material is the bioflexible conductive material of the first aspect of the present application. In some embodiments, S102 includes the steps of: S1021, obtaining a preset printed pattern; S1022, cutting the printed pattern using the width of the light curing device to obtain a plurality of unit printed patterns, wherein the area of a unit printed pattern is the same as or similar to the area of the width; S1023, obtaining the electrode distribution density of the unit printed pattern, wherein the electrode distribution density = the area of the electrode in the width / the width; S1024, selecting a corresponding curing speed for a plurality of unit printed patterns according to the electrode distribution density; wherein the greater the electrode distribution density, the faster the curing speed of the unit printed pattern; S1025, segmentally curing a plurality of unit printed patterns using the curing speed respectively.

[0024] Compared with the prior art, the present application has at least the following beneficial technical effects: At present, the manufacturing and integration of bioflexible electrodes still face major technical challenges. Many existing flexible electrode manufacturing processes are complex, expensive, and difficult to perform high-resolution patterning and microstructure manufacturing. In addition, flexible electrodes usually need to be closely combined to a flexible substrate (such as polyimide, PDMS, etc.) to ensure their stability during use. However, the interfacial bonding strength between different materials is usually weak, leading to delamination or fracture during repeated bending and stretching, which can adversely affect the performance and life of the flexible electrode.

[0025] To prepare a bio-flexible conductive material with excellent conductivity, mechanical properties and biocompatibility, the present application creatively mixes polyether F127-diacrylate (abbreviated as: F127DA) and conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (abbreviated as: PEDOT:PSS) solution, and combines with light curing technology to prepare conductive hydrogel PPF. It should be noted that although there are existing technologies for mixing polyether F127-diacrylate and conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) to prepare conductive hydrogel, the technical solutions of these existing technologies are generally to add PEDOT:PSS to polyether F127-diacrylate hydrogel (for example, Chinese patent application CN115957181A, CN111154120A), or to mix PEDOT:PSS solution and other polymers (such as polyethylene glycol dimethacrylate) first, and then add polyether F127-diacrylate as a dopant (for example, Chinese patent application CN118079037A), or to further add dopamine hydrochloride and sodium hydroxide after mixing polyether F127-diacrylate and PEDOT:PSS (for example, Chinese patent application CN115957181A). However, the conductivity of the hydrogel of these existing technologies is generally low (for example, less than 10 S / m, for example, about 2 S / m), so it can only be used as an in-situ injection hydrogel or a patch layer of an electrode, and cannot be prepared into a bio-flexible electrode.

[0026] It should be emphasized that by dissolving a suitable amount and suitable degree of substitution of F127DA in a suitable concentration of PEDOT:PSS aqueous solution, the F127DA polymerizes into a micellar network, and the uniformly dispersed PEDOT:PPS long chains interpenetrate with the micellar network of F127DA, promoting the mutual connection between the PEDOT:PPS long chains and forming a stable organic conductive network. In other words, the components of the conductive hydrogel of the present application (and their order of addition) produce a synergistic effect. On the one hand, the addition of PEDOT:PSS not only does not negatively affect the original tensile properties of the micellar network formed by F127DA, but also further improves its tensile properties and toughness. On the other hand, the conductive network formed by the present application enables smoother transmission of charges between PEDOT:PPS long chains, i.e. the conductive hydrogel of the present application can form a stable conductive path without the need to incorporate other conductive substances / promote conductive substances, effectively improving the conductivity, and the electrical conductivity can reach more than 20 S / m.

[0027] In addition, the conductive hydrogel formed by the acid treatment of the conductive hydrogel, instead of the conventional idea of peeling off the PEDOT and PSS in the prior art, can effectively remove part of the excess PSS short chain to increase the proportion of PEDOT, without causing negative effects on the micellar network formed by F127DA. On the contrary, the conductive network is more uniform, avoiding the aggregation of PEDOT, ensuring high tensile properties and further improving the conductivity, so that the conductivity of the formed conductive hydrogel can exceed 300 S / m without the introduction of other substances. That is, the conductive hydrogel prepared by the present application has excellent conductivity, mechanical properties and biocompatibility, and can be combined with 3D printing technology to obtain a bio-flexible electrode with good conductivity, mechanical properties and biocompatibility. The bio-flexible electrode can exhibit stable electrical properties for a long period of time, showing the prospect of long-term implantable soft bioelectronics and other potential biomedical applications.

[0028] The development of DLP-based 3D printing technology provides new possibilities for the manufacture of bio-flexible electrodes. The inventors of the present application found that the conductive hydrogel with other conductive substances / promoting conductive substances (such as carbon nanotubes, metal nanoparticles) is not suitable for printing bio-flexible electrodes based on DLP-based 3D printing technology, which will affect the light path, and thus lead to low quality of the printed bio-flexible electrodes. Using the bio-flexible conductive material of the present application as printing ink and using DLP-based 3D printing technology with patterned exposure and combining with splicing printing, the shape and structure of the bio-flexible electrode can be accurately controlled at high speed and high precision, so as to realize the rapid customization of high-resolution, multi-channel and larger size flexible electrodes, and broaden the application range of 3D printed flexible electrodes.

[0029] The packaging and protection of bioflexible electrodes are critical considerations. Bioflexible electrodes need to work stably for a long time in biomedical applications, which makes their packaging and protection critical. Bioflexible electrodes need an encapsulation layer to provide non-insulating contacts, prevent short circuits between circuits. The encapsulation layer also reduces the contact between the circuit and the external environment, providing protection and extending the life of the electrode. When the bioflexible electrode is repeatedly bent and stretched during use, the encapsulation layer can provide additional mechanical support to prevent electrode failure. However, using traditional packaging materials and methods, it is challenging to balance flexibility and sealing during packaging. On the basis of the bioflexible conductive material provided by the present application, the present application also provides a DLP-based 3D printing technology to quickly manufacture a flexible bioelectrode (i.e. bioflexible electrode patch) with an encapsulation layer structure (for example, a patch layer prepared from F127DA) to quickly encapsulate the bioflexible electrode. Since the packaging material is the same as the substrate of the bioflexible electrode, the patch layer of the present application can be closely combined with the bioflexible electrode to provide effective protection. It has been verified that the flexible bioelectrode prepared by the present application can transmit physiological electrical signals and has potential application value in the biomedical field. Even, see Figure 6 As shown in the figure, even if it is prepared into an elongated wire shape (or strip shape), it can have good stretchability, so it can better adapt to the biological entity during actual application.

[0030] In summary, the present application provides a new type of flexible conductive composite material for bioelectronics and a rapid photocuring forming method thereof. The present application uses polyether F127-diacrylate as an elastic network skeleton, uniformly dopes a conductive polymer in a conductive polymer solution, and prepares a semi-interpenetrating double network hydrogel; then the excess small molecules are removed by mild glacial acetic acid treatment and the chain segments are induced to rearrange. The flexible conductive composite material provided by the present application is a conductive elastomer material, which has a stretchability of more than 300%, can be freely bent, and also maintains good conductivity, which can exceed 300S / m, and can maintain long-term stability even in repeated stretch and rebound tests.

[0031] The bio-flexible conductive material prepared by the application has excellent conductivity, mechanical property and biocompatibility, can be combined with 3D printing technology to obtain a bio-flexible electrode with good conductivity, mechanical property and biocompatibility, and the bio-flexible electrode can exhibit stable electrical performance for a long period of time. Relying on digital light processing printing and splicing alignment strategy, the application realizes the "integration" rapid manufacturing of the flexible electrode layer and the upper and lower packaging layers and customizes the metal-free multi-channel electrode, significantly improving the forming efficiency and consistency of the large-area and high-resolution flexible electrode. The device prepared based on the application has good biocompatibility and biological adhesion, can stably record the cortical nerve signal and effectively stimulate the peripheral nerve, and is suitable for brain-computer interface, electromyography / electrocardiogram monitoring and implantable bioelectricity regulation scenes. The application improves the bottleneck of the existing flexible electrode, such as low conductivity, complex packaging and large-size printing limitation, from the material system to the manufacturing process, provides a universal and efficient new scheme for implantable soft bioelectronics, and shows the prospect of long-term implantable soft bioelectronics and other potential biomedical applications. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual proportion. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without paying creative labor.

[0033] Figure 1 The preparation and application process of the bio-flexible conductive material (i.e. conductive hydrogel); Figure 2a The XPS result graph of PPF hydrogel before and after acid treatment; Figure 2b The twisting and stretching result graph of PPF (H+) hydrogel; Figure 2c The stretching result graph of PPF (H+) hydrogel; Figure 2d The tensile stress-strain curve of F127DA hydrogel, PPF hydrogel and PPF (H+) hydrogel; Figure 2e The tensile strain result graph of F127DA hydrogel, PPF hydrogel and PPF (H+) hydrogel; Figure 2f The tensile strength result graph of F127DA hydrogel, PPF hydrogel and PPF (H+) hydrogel under 250% strain; Figure 2g Tensile modulus results for F127DA, PPF and PPF (H+) hydrogels; Figure 2h Conductivity results for F127DA hydrogel, PPF hydrogel and PPF (h+) hydrogel; Figure 2i Resistance change results for PPF (H+) hydrogel after 300 stretching cycles; Figure 2j Live / dead staining results for NIH / 3T3 cells at 24 hours, 48 hours and 72 hours (live cells are green and dead cells are red); Figure 2k Survival rate results for NIH / 3T3 cells at 24 hours, 48 hours and 72 hours; Figure 2l OD value results for CCK-8 cell proliferation assay; Figure 3 Preparation and characterization results for PPF (H+) electrode; Figure 4 Schematic diagram of sciatic nerve stimulation by PPF (H+) electrode; Figure 5 Results of conductive hydrogel of OA prepared by different concentrations of F127DA; Figure 6 Stretching effect comparison results of conductive hydrogels prepared by different gel raw materials; Figure 7 Results of strip-shaped conductive hydrogel prepared by the present application; Figure 8 Characterization results of PPF hydrogel; Figure 9 Structure diagram of a bioflexible electrode patch in an exemplary embodiment of the present application; Figure 10 Results of PPF hydrogel soaked in saline for different lengths of time; Figure 11 Five-organ staining results after implanting PPF (H+) hydrogel subcutaneously on the back of a rat for two weeks; Figure 12 Schematic diagram of cutting scheme of printed pattern; Figure 13 Results of recording cortical electrical signals of a rat using PPF (H+) electrode. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application. In this document, using suffixes such as "module", "component" or "unit" for elements is only for the convenience of describing the present application, and it does not have a specific meaning. Therefore, "module", "component" or "unit" can be mixedly used. In this document, the terms "upper", "lower", "inner", "outer", "front", "back", "one end" and "the other end" indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In this document, unless otherwise clearly specified and limited, the terms "mount", "provided with", "connected" and the like should be understood in a broad sense, for example, "connected" can be fixed connection, can be detachable connection, or integral connection; can be mechanical connection, can be direct connection, or indirect connection through an intermediate medium, can be the communication inside two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] In this document, "and / or" includes any and all combinations of one or more of the associated items. In this document, "plurality" means two or more, that is, it includes two, three, four, five, etc. In this specification, the term "about" typically means + / - 5% of the stated value, more typically + / - 4% of the stated value, more typically + / - 3% of the stated value, more typically + / - 2% of the stated value, even more typically + / - 1% of the stated value, even more typically + / - 0.5% of the stated value. In this specification, certain embodiments can be disclosed in a format that is a range of values. It is to be understood that such a "range of values" format is simply used to simplify the description and is not to be construed as limiting the scope of the disclosed range. Therefore, the description of the range should be considered to have specifically disclosed all possible sub-ranges and individual numerical values within the range. For example, a description of a range 1-6 should be considered to have specifically disclosed sub-ranges like from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within the range, such as 1, 2, 3, 4, 5, and 6. The above rule applies regardless of the breadth of the range.

[0036] Detailed description of the attached figures Figure 3 The fabrication and characterization of the PPF (H+) electrode are shown. a) Printed pattern of the electrode. b) Individually printed pattern of the electrode. c) 3D printed PPF electrode. d) Schematic diagram of the PPF electrode fabricated with an encapsulation layer. e) Image of the PPF (H+) electrode. f) Resistance of the PPF (H+) electrode after 28 days. g) Stretched image of the PPF (H+) electrode attached to the back of a mouse. Figure 4 The diagram illustrates the use of PPF (H+) electrodes for sciatic nerve stimulation. a) Schematic diagram of sciatic nerve stimulation using PPF (H+) electrodes. b) Image of a flexible electrode wrapped around the sciatic nerve in a rat. c) Comparative images of foot movement amplitude under different electrical stimulations. d) Conduction velocity of the sciatic nerve after stimulation with different flexible electrodes. e) Latency of the sciatic nerve after stimulation with different flexible electrodes. f) Amplitude of waves generated by different flexible electrodes. Figure 8 a) Synthesis route of F127DA. b) Rheological properties of PPF material system before and after photocuring. c) Contact angle measurement images of F127DA hydrogel, PPF hydrogel, and PPF(H⁺) hydrogel. d) Statistical analysis of contact angle measurements of F127DA hydrogel, PPF hydrogel, and PPF(H⁺) hydrogel. Data are expressed as p < 0.001 (n = 6). Figure 13 a) Schematic diagram of rat EEG signal acquisition using PPF(H⁺) electrodes. b) Representative image of rat cerebral cortex EEG signals acquired using PPF(H⁺) electrodes. c) Multichannel recording of rat cerebral cortex electrical activity using PPF(H+) electrodes. d) Recording results of the rat brain (low-pass filtered at 300 Hz). e) Single unit spike extracted from high-frequency data by waveform classification. f) PSD of neural signals showing the frequency components of recorded brain activity. g) Average signal amplitude and noise level for each channel (values ​​below the red line indicate a signal-to-noise ratio greater than 10 dB).

[0037] Example 1: Preparation of conductive hydrogels: Polyether F127 diacrylate (F127DA) can be prepared using existing commercial materials, or it can be prepared using polyethylene oxide-polypropylene oxide (F127) (see [link to documentation]). Figure 8 a), so that the substitution degree of F127DA is maintained at 95%~100%.

[0038] The conductive hydrogel printing ink was obtained by mixing F127DA and LAP in a PEDOT:PSS aqueous solution (CLEVIOS PH1000, 1.5% w / v). F127DA (its final concentration in the composite system was about 5%, 10%, 15% and 20% w / v) and the photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP, 1% w / v) were dissolved in the PEDOT:PSS aqueous solution to prepare the 3D printing ink of the conductive hydrogel (i.e. the composite system). The conductive hydrogel printing ink was photopolymerized under 365 nm ultraviolet light to form the conductive hydrogel PPF.

[0039] Further, the crosslinked conductive hydrogel PPF was soaked in glacial acetic acid overnight, and then washed with water to remove the residual acid solution to obtain the PPF(H+) hydrogel.

[0040] Characterization of the conductive hydrogel: The PPF hydrogel and the PPF(H+) hydrogel were respectively soaked in 30%, 45%, 60%, 75%, 90% and anhydrous ethanol solution for gradient dehydration, and then subjected to critical point drying. The dried samples were ground into powder and analyzed using X-ray photoelectron spectroscopy (XPS).

[0041] To test the stretchability of the conductive hydrogel, a tensile test was performed on the strip-shaped hydrogel using a universal mechanical testing machine. The hydrogel samples in the shape of a cube were prepared, and their resistance was measured using a four-probe tester. The measured values were converted to obtain the conductivity of the hydrogel samples.

[0042] In addition, to measure the resistance change of the conductive hydrogel under cyclic stretching, the prepared strip-shaped conductive hydrogel was connected to a conductive silver paste and a platinum wire, and the resistance was measured at a strain of 50% during the stretching process using a universal mechanical testing machine.

[0043] Cell viability and proliferation test: The prepared conductive hydrogel was soaked and washed in DMEM complete medium, and the hydrogel extract was used for NIH / 3T3 cell culture. The survival rate and proliferation of NIH / 3T3 cells were detected using a live / dead test kit and CCK-8.

[0044] Splicing printing of flexible electrodes: By connecting the motor to move the 3D printing light path along the X and Y axes, the image was divided into 5x5 small images, and the flexible electrode was printed by 25 displacement and exposure.

[0045] Preparation of flexible electrode with encapsulation layer: using the layer-by-layer printing method, first print the lower encapsulation layer (or called patch layer) with F127DA solution (15% w / v). After removing the uncured solution, correct the printing position, and add PPF 3D printing ink to print the conductive layer. After removing the uncured printing ink, correct the position again. Add F127DA solution (15% w / v) to print the upper encapsulation layer (or called patch layer) to obtain the PPF electrode. After removing the uncured solution, immerse the electrode in glacial acetic acid and wash to obtain the PPF (H+) electrode.

[0046] Long-term electrical stability of the electrode: measure the conductivity of the PPF (H+) hydrogel at 0, 7, 14, and 28 days to evaluate its long-term stability.

[0047] Epidermal adhesion: place and adhere the prepared flexible PPF (H+) electrode on the skin of the back of a rat. Subsequently, stretch the rat's back skin and observe whether the flexible electrode deforms with the stretching.

[0048] Animal experiments: 8-week-old rats were purchased from Beijing Huafukang Bioscience Co., Ltd. Electromyography was used for sciatic nerve stimulation testing using flexible electrodes. Physiological signal system was used to detect the electrocardiogram of rats using flexible electrodes.

[0049] Statistical analysis: All statistical analyses were performed using Origin 2021. One-way ANOVA was used to determine the statistical significance between different experimental groups, P<0.05 was considered statistically significant (*P<0.05, **P<0.01, ***P<0.001, ****P<0.0001), P>0.05 was considered not statistically significant (NS).

[0050] Example 2: In order to obtain high-quality hydrogel-based flexible electrodes, the present application designs a light-curable conductive elastic hydrogel material system, i.e. mixing F127DA with PEDOT:PSS aqueous solution and preparing a conductive hydrogel PPF by photopolymerization. The preparation and application process of the conductive hydrogel is as shown in Figure 1 .

[0051] In order to evaluate the light-controllability of this above-mentioned hydrogel material system, this embodiment carries out rheological experiment to systematically analyze the light crosslinking behavior of PPF precursor solution. As shown in Figure 8 b, before 405 nm light irradiation, the storage modulus (G') is significantly lower than the loss modulus (G''), which indicates that the hydrogel is in a flowable liquid state. After 405 nm light irradiation, the storage modulus (G') is significantly higher than the loss modulus (G''), which proves that the sol-gel transition is successfully achieved, providing a material basis for 3D printing based on digital light processing (DLP).

[0052] The screening results show that the conductive hydrogel fabricated using the DLP-based 3D printing device has a clearer edge profile when the concentration of F127DA exceeds 15% (w / v) Figure 5 ). The printing operation becomes difficult as the concentration of F127DA increases.

[0053] In the present exemplary embodiment, the conductive hydrogel PPF prepared using the 3D printing ink with a F127DA concentration of 15% (w / v) (i.e., the composite system prepared above) exhibits long-term chemical stability in physiological saline. Figure 10 In the photograph on day 0, the left tube shows the PEDOT:PSS solution with the same concentration as the PPF hydrogel prepared, which is darkish black. In the other photographs, the left tube contains physiological saline, while the right tube shows the PPF hydrogel immersed in physiological saline. After continuous immersion, the PEDOT:PSS in the PPF hydrogel does not leach out, and the immersed saline solution remains colorless and transparent. During the continuous immersion in saline for 28 days, the solution remains clear, indicating that the PEDOT S in the PPF hydrogel does not leach out Figure 10 ).

[0054] Example Three: The PEDOT:PSS solution generally contains some long-chain insulating PSS monomers that are not combined with PEDOT. This embodiment can remove the PSS monomers to obtain a PPF (H+) hydrogel by immersing the PPF hydrogel in an acidic solution, thereby increasing the proportion of the conductive polymer PEDOT in the hydrogel and enhancing the conductivity of the PPF hydrogel.

[0055] Since both PEDOT and PSS contain sulfur elements, while F127DA does not, the energy level orbit of the sulfur element can be selected to examine and analyze the conductive hydrogel before and after acid treatment by using X-ray photoelectron spectroscopy (XPS). Scanning the S2p characteristic orbit of the two hydrogels shows that the ion flow intensity in the range of the electron binding energy of the PEDOT molecule is similar, while the ion flow intensity in the range of the electron binding energy of the PSS molecule in the PPF (H+) hydrogel group is significantly lower than that in the PPF hydrogel group Figure 2a ). The results show that the acid treatment successfully removes the unbound PSS molecules from the PPF hydrogel.

[0056] Contact angle measurements (Cobb's test) Figure 8 c、 Figure 8 d) show that the hydrophobicity increases after acid treatment, which reflects that the removal of PSS leads to a decrease in hydrophilicity and an enhancement of PEDOT surface enrichment, thereby adjusting the surface energy and wettability, which to some extent contributes to the improvement of the conductivity of the PPF hydrogel (especially the PPF (H+) hydrogel).

[0057] Example Four Characterization of the conductive hydrogel: By using DLP-based 3D printing technology, the strip-shaped PPF(H+) hydrogel was prepared, which could be twisted and stretched without breaking Figure 2b .

[0058] To further explore its stretchability, the present embodiment uses a universal mechanical testing machine to conduct a tensile test Figure 2c . The results show that, like F127DA hydrogel, PPF hydrogel and PPF(H+) hydrogel can both reach a tensile strain rate of about 300% Figure 2d . The tensile strain of F127DA hydrogel is (432.82±66.71)%, and the tensile strains of PPF and PPF(H+) hydrogel are (390.27±37.37)% and (293.60±33.63)% respectively Figure 2e . At a tensile strain of 250%, the tensile strength of F127DA hydrogel is (69.43±5.35) kPa, which is significantly lower than that of PPF hydrogel (175.57±22.30) kPa and PPF(H+) hydrogel (167.60±21.88) kPa Figure 2f . The above results show that, compared with F127DA hydrogel, the tensile strength of the conductive hydrogel PPF prepared by the present application is actually improved. As shown in Figure 2g , the tensile modulus calculation results of the three kinds of hydrogels are as follows: F127DA hydrogel (23.91±1.27) kPa, PPF hydrogel (73.64±7.40) kPa, and PPF(H+) hydrogel (64.97±7.64) kPa.

[0059] The present embodiment also measures the conductivity of the prepared hydrogel using a four-probe tester. The results show that the conductivity of PPF hydrogel is (24.09±0.85) S / m, while the conductivity of PPF(H+) hydrogel obtained after acid treatment increases by more than ten times, reaching (329.54±7.70) S / m Figure 2h . Removing excess PSS molecules through acid treatment significantly improves the conductivity of the hydrogel.

[0060] In addition, the present embodiment studies the change in the conductivity of PPF(H+) hydrogel after cyclic stretching. The present embodiment measures and records the resistance Rs of PPF(H+) hydrogel at a fixed strain of 50% for 300 cycles, and plots the curve compared with the initial resistance R0 before stretching Figure 2i . The test results show that the resistance of PPF(H+) hydrogel does not change significantly during repeated stretching and recovery, indicating that it has good electrical stability.

[0061] Referring to Figure 6The present embodiment also tests the conductive hydrogel prepared by mixing different types of hydrogel with PEDOT. The results show that the conductive material prepared based on methacrylated gelatin (GelMA) has poor tensile properties and the conductivity is only half of PPF. The conductive material prepared based on polyethylene glycol diacrylate (PEGDA) is almost not stretchable. In contrast, the conductive material prepared by F127DA has excellent tensile properties and conductivity. The above results show that not any hydrogel and PEDOT:PSS aqueous solution can obtain a conductive hydrogel with excellent tensile properties and conductivity.

[0062] Through analysis, the reason for the above experimental results may be that the components of the conductive hydrogel prepared by the present application have a synergistic effect. PEDOT:PSS is a long-chain polymer. After dissolving a suitable amount and suitable degree of substitution of F127DA in a suitable concentration of PEDOT:PSS aqueous solution, the F127DA polymerizes into a micellar network, and the uniformly dispersed PEDOT:PPS long chain and the micellar network of F127DA interpenetrate each other, promoting the mutual connection between the PEDOT:PPS long chain, and forming a stable organic conductive network. On the one hand, the addition of PEDOT:PSS does not negatively affect the original tensile properties of the micellar network formed by F127DA, but further improves its tensile properties and toughness. On the other hand, the conductive network formed by the present application makes the transmission of electric charges between the PEDOT:PPS long chain more smooth, that is, the conductive hydrogel of the present application can form a stable conductive path without adding other conductive substances / promoting conductive substances, thereby effectively improving the conductivity. And the present application can remove part of the excess PSS short chain to increase the PEDOT proportion by acid treatment of the conductive hydrogel, which does not negatively affect the micellar network formed by F127DA, but makes the conductive network more uniform, ensures high tensile properties, and further improves the conductivity, so that the conductivity of the formed conductive hydrogel can exceed 300 S / m without additional introduction of other substances.

[0063] Biocompatibility of electrode material: In order to evaluate the cell compatibility of the material for manufacturing flexible electrodes, NIH / 3T3 cells were cultured in DMEM complete medium, DMEM complete medium extract of F127DA hydrogel and DMEM complete medium extract of PPF (H+) hydrogel. The cell viability and proliferation at 24 hours, 48 hours and 72 hours were evaluated. The live / dead staining results show that there is no significant difference in cell viability of the three groups at 24 hours, 48h and 72 hours, and the cell viability is >95% (Fig. 6). Figure 2j and Figure 2k). In addition, the cell proliferation test results show that PPF hydrogel and PPF (H+) hydrogel have no significant effect on the proliferation of NIH / 3T3 cells (Fig. 2b), showing good cell compatibility. Figure 2l

[0064] To study the in vivo biological safety of PPF (H+) hydrogel, PPF (H+) hydrogel was implanted subcutaneously in the back of rats. Another group of rats without implanted hydrogel served as the control group. Two weeks later, histological evaluation was performed on the heart, liver, spleen, lung and kidney of the two groups. The results show that the implanted hydrogel material has no obvious toxic side effects on the major organs of rats (Fig. 3b), indicating good biological safety. Figure 11

[0065] Specifically, Figure 11 It is shown that after two weeks of subcutaneous implantation of PPF (H+) hydrogel in the back of rats, the organs of rats in the experimental and control groups were collected and subjected to H&E staining. There is no significant difference between the organs of the two groups.

[0066] Example Five: Preparation of PPF (H+) electrode with encapsulation layer: In order to manufacture large-scale, high-precision flexible electrodes, this embodiment designs a splicing printing system. By dividing the printed pattern (or, printed pattern) (see Fig. 4a) into 5x5 small patterns (Fig. 4b), and moving the sample using a displacement stage, block-by-block printing is performed. By this method, PPF (H+) electrodes with a line width of about 10 μm and a length of up to 30 mm can be manufactured (Fig. 4c). Figure 3 Figure 3 Figure 3

[0067] A flexible electrode with upper and lower encapsulation layers is manufactured using a layer-by-layer printing method, and a camera-assisted alignment printing mode is used to avoid misalignment between different layer structures (Fig. 5b). The printing process is shown in Fig. 5d. After three printing cycles, a flexible electrode with encapsulation layers is obtained, and finally a PPF (H+) electrode is obtained after acid treatment (Fig. 5e and Fig. 5f), realizing the fixation of hydrogel flexible electrode with anisotropic conductive adhesive and soft wire. Figure 5 Figure 3 Figure 3 Figure 7 To evaluate the long-term electrical stability of PPF (H+) electrode, this embodiment stores it in PBS buffer and measures its electrical conductivity at 7, 14 and 28 days. The results show that PPF (H+) electrode maintains a relatively stable electrical conductivity in water environment for a long time. The electrical conductivity remains above 300 S / m after 28 days (Fig. 6f), indicating its potential for long-term use in vivo.

[0068] Figure 3 f), indicating its potential for long-term use in vivo. ​​​​​​​​​

[0069] After the PPF (H+) electrodes were placed on the shaved skin of the rats, they adhered well to the skin. The electrodes did not separate when the skin on the rat's back was stretched. Figure 3 g), indicating good bioadhesion.

[0070] Sciatic nerve stimulation using PPF (H+) electrodes: The sciatic nerve of rats was stimulated using PPF (H+) electrodes, and the electromyography generated by the sciatic nerve was recorded to obtain the corresponding conduction velocity, latency, and amplitude. Figure 4 a). Take two PPF (H+) electrodes, wrap the exposed conductive layer end (top packaging layer facing up) around the rat sciatic nerve, and connect the other end to the positive and negative poles of the electrical stimulation signal output. The PPF (H+) electrodes adhere well to the surrounding nerve, requiring no additional adhesion or sutures. Figure 4 b). After connection, currents of 50mA and 100mA were output respectively, and the foot movements of the rats were observed. As the output current increased, the amplitude of the foot movements increased significantly. Figure 4 c). Then, the output current was fixed at 100mA, and the untreated PPF electrode was used as a control group. The conduction velocity, latency, and amplitude generated by the flexible electrode were recorded. Statistical analysis of the results showed that there was no significant difference in conduction velocity and latency of the rat sciatic nerve among different electrodes. Figure 4 d and Figure 4 e). However, the amplitude of the sciatic nerve produced by the PPF (H+) electrode group in rats was significantly higher ( Figure 4 f), indicating that PPF(H+) electrodes have better conductivity and potential applications in the detection, transmission and neural modulation of physiological electrical signals.

[0071] This embodiment also features a groove designed on the bottom encapsulation layer for fixing and placing the brain organoid, such as... Figure 9 As shown. To evaluate the practical effect of flexible electrodes in capturing electrical signals in a biological environment, this embodiment used a rat model to conduct a cortical signal recording experiment (…). Figure 13 a, Figure 13 b). The PPF(H⁺) flexible electrode successfully recorded multi-channel cortical electrical signals with high fidelity. Figure 13 c). For example Figure 13 As shown in d, after a 300 Hz low-pass filter, the recorded signal exhibits a clear, stable, and high-quality waveform, indicating that the flexible electrode has excellent low-noise characteristics and signal reliability, and can be used for cortical activity monitoring.

[0072] To describe the characteristics of the recorded signal in more detail, power spectral density (PSD) analysis was performed in this embodiment. The results show that there is significant oscillatory activity in multiple high-frequency bands. Figure 13f), which indicates that the flexible electrode can accurately detect the subtle dynamics of neurons. In addition, spike sorting analysis can also extract neuron firing events from high-frequency signal components and classify them, thereby identifying single neuron action potentials (flexible electrode e). This highlights the high spatial resolution and accurate spike detection capability of the electrode.

[0073] To comprehensively evaluate the electrode performance, the average signal amplitude and background noise of all recording channels were quantified, and the signal-to-noise ratio (SNR) of each channel was calculated. As shown in Fig. Figure 13 g, the signal-to-noise ratio of most channels exceeds 10 dB (red line), demonstrating the high sensitivity, stability and robustness of the PPF(H⁺) electrode in neural recording applications. These results highlight the great potential of this electrode in future biomedical applications.

[0074] The PPF(H⁺) electrode with a packaging layer in this embodiment is prepared using a layered and segmented printing technology, and the specific preparation process is shown in Example 6.

[0075] Further, the present application also provides a method for preparing a biological flexible electrode patch, which comprises a first patch layer and a second patch layer (equivalent to a packaging layer), and a biological flexible electrode is arranged between the first patch layer and the second patch layer, and the biological flexible electrode is prepared by using the composite material provided by the present application. In order to realize the high-quality preparation of this multi-layer electrode patch, the present application actually provides a layered and segmented multi-layer patch curing method (or printing method), which comprises the following steps: S101, providing a layer of liquid hydrogel, and using a light curing device to cure the liquid hydrogel using a first exposure intensity for a first duration to form a first patch layer; preferably, a guide groove is also provided on the first patch layer, which is recessed inward along the surface of the first patch layer, which can be used to accommodate the electrode to enhance the adhesion stability between the electrode and the first patch layer.

[0076] S102, covering a layer of liquid composite material on the first patch layer, and using a light curing device to segmentally cure the liquid composite material using a second exposure intensity for a second duration to form a corresponding printing pattern on the first patch layer, the printing pattern is composed of at least one electrode, and the width of the input end of the electrode is greater than the width of the main body of the electrode (such as the width of the first connecting segment and the second connecting segment); As shown in Fig. Figure 3 (a) of Fig. Figure 3 shows an exemplary printing pattern, i.e. the distribution relationship of the electrode on the first patch layer. Referring to Fig. Figure 12As shown, along its axial direction, the electrode includes: an output segment 10 arranged along a first distribution density; a first connecting segment 11 arranged along a second distribution density, with the first end of the output segment 10 continuing to connect to the second end of the first connecting segment 11; a second connecting segment 12 arranged along a third distribution density, with its second end connected to the first end of the first connecting segment 11; and a third connecting segment 13 arranged along a fourth distribution density, with its second end connected to the first end of the second connecting segment 12. Preferably, the first, second, and third distribution densities gradually decrease; preferably, the fourth distribution density is greater than the third distribution density.

[0077] In this embodiment, the output segment 10 is used to connect to the conductive interface of an external device, and its width is greater than that of the first connection segment 11. Furthermore, the second connection segment 12 can be configured with a higher distribution density, i.e., it can be configured using a dense cabling method, to reduce the volume of the electrode patch's tip, thereby facilitating limited contact with the biological wound. It is understood that by reducing the size of the electrode patch's tip, the impact of the electrode patch on biological activities can be minimized.

[0078] The first connection segment 11 can be arranged in a radial shape away from the second connection segment 12 to facilitate connection with the interface of external devices. The third connection segment 13 is formed by extending from the first end of the second connection segment 12, and the electrode distribution density at the input end is less than that of the second connection segment 12.

[0079] Preferably, the width of the second end electrode in the third connecting segment 13 gradually increases, such as... Figure 12 As shown, a circular contact area 131 is formed at the second end, which is used to attach to the surface of a biological wound (or biological skin). It is understood that the shape of the contact area can also be set to any other arbitrary shape, such as square, ellipse, etc. It can be seen that, in order to achieve coupling and connection between the multi-electrode patch and the external device and the biological wound, this invention has segmented and optimized its electrode layout, and this complex segmented electrode pattern also places higher demands on the fabrication process.

[0080] S103, a layer of liquid hydrogel is further coated on the printed pattern, and the liquid hydrogel is cured using a photocuring device with a third exposure intensity for a third duration; preferably, the third duration is shorter than the first duration.

[0081] In some embodiments, the hydrogel used in S101 and S103 is F127DA hydrogel. In some embodiments, the light curing device can be a light curing device based on DLP (Digital Light Processing) technology. In some embodiments, the exposure intensity and duration can be pre-set by the user. In some embodiments, during the interval between the two curing processes, the residual uncured liquid needs to be flushed. In some embodiments, the first exposure intensity is greater than the third exposure intensity.

[0082] In some embodiments, S102 includes the following steps: S1021, obtaining a preset printing pattern; wherein the printing pattern refers to the distribution form of the electrodes on the first layer of the patch; S1022, cutting the printing pattern using the width of the light curing device, thereby obtaining a plurality of unit printing patterns, wherein the area of a unit printing pattern is the same as or similar to the area of the width; for example, the area of a unit printing pattern is similar to the area of the width, which means that the difference between the two areas does not exceed a preset difference value, such as not more than 5%, or even not more than 10%; S1023, obtaining the electrode distribution density of the unit printing pattern, wherein the electrode distribution density = the area of the electrodes in the width / the width; S1024, selecting a corresponding curing speed for the plurality of unit printing patterns according to the electrode distribution density; wherein the greater the electrode distribution density, the faster the curing speed of the unit printing pattern; S1025, using the curing speed to segmentally cure the plurality of unit printing patterns.

[0083] In some embodiments, the width refers to the area that can be covered by the laser emitted by the light curing device at the same time, or in other words, the width refers to the area that can be cured by the light curing device at the same time. It can be understood that the size of the width can be determined according to the hardware configuration or software configuration of the light curing device. In actual application, the user can adjust the width of the light curing device according to different printing schemes. In this embodiment, the same unit printing pattern uses the same light curing speed, such as the same exposure intensity.

[0084] In this embodiment, the entire printing pattern is segmented and formed according to the electrode distribution density of the width, which can alleviate the problem of uneven printing and improve the conductivity of the non-metal electrodes. For example, the segmented formation based on different curing speeds can avoid the problem of overexposure in local areas.

[0085] Further, in some embodiments, S1022 comprises: S10221, cutting the printing pattern with a surface to obtain a plurality of unit printing patterns; S10221, calculating a distribution difference of at least one unit printing pattern; wherein S10221 comprises: calculating at least two sub-electrode distribution densities of at least two sub-patterns in the unit printing pattern; calculating at least two difference values between the at least two sub-electrode distribution densities and the electrode distribution density; calculating an average value of the at least two difference values as the distribution difference; S10222, judging whether the current cutting scheme meets the cutting rule; wherein the cutting rule requires that the distribution difference is less than a first set difference value, and an average value of a plurality of the distribution differences is less than a second set difference value, the first set difference value being greater than the second set difference value; if yes, executing S1023-S1025. In this embodiment, the distribution difference is used to evaluate the uniformity of the electrode arrangement.

[0086] It is worth noting that the present application actually provides a preparation method suitable for complex multi-layer electrode patches. The method improves the printing uniformity of complex printing patterns through layered and segmented preparation technology, avoiding the problem of local overexposure.

[0087] Specifically, the present application provides a segmented multi-density distribution design for the printing pattern, and based on the segmented multi-density distribution design, a distribution difference based on the density of the sub-regions is used to comprehensively evaluate the local uniformity and overall uniformity of the printing pattern, so as to provide an optimal cutting means for complex printing patterns, thereby relieving or avoiding the problems of local overexposure and unclear edges.

[0088] In order to explain the preparation method adopted by the present application, the preparation method will be introduced again in another description manner. The method comprises: S1: mixing polyether F127-diacrylate and a photoinitiator with a conductive polymer solution to prepare a composite material; S2: obtaining a printing pattern of a biological flexible electrode; S3: inputting the printing pattern into a light curing device, the light curing device corresponding to output projection light, the projection light irradiating on the composite material to print the corresponding printing pattern thereon, obtaining the biological flexible electrode. In some embodiments, the conductive polymer can be poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid). In some embodiments, S2 comprises: cutting the printing pattern to correspondingly obtain a plurality of unit printing patterns. In some embodiments, S3 comprises: using a hydrogel as a substrate and printing the biological flexible electrode thereon. In some embodiments, S3 comprises: the substrate is prepared from polyether F127-diacrylate.

[0089] It should be noted that, in this text, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent in such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus including the element. Through the description of the above embodiments, those skilled in the art can clearly understand that the above example method can be realized by software plus a general hardware platform, of course, it can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes a plurality of instructions for making a computer terminal (which can be a mobile phone, computer, server, or network device, etc.) execute the method described in each embodiment of the present application. The embodiments of the present application are described above in conjunction with the drawings, but the present application is not limited to the above specific embodiments, and the above specific embodiments are only illustrative, not limiting, and those skilled in the art can make many forms under the inspiration of the present application without departing from the scope of the present application and the scope of protection of the claims.

Claims

1. A bio-flexible conductive material, characterized in that, The bio-flexible conductive material is prepared by photoforming a mixed system and has a predetermined shape. The mixed system is prepared by dissolving polyether F127-diacrylate in a conductive polymer solution, wherein the concentration of polyether F127-diacrylate in the mixed system is 10-20% (w / v); the concentration of the conductive polymer in the mixed system does not exceed 1.5% (w / v); the degree of substitution of polyether F127-diacrylate is ≥95%, and the conductive polymer optionally includes: poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid).

2. The bio-flexible conductive material according to claim 1, characterized in that, The bio-flexible conductive material is also subjected to acid treatment.

3. The bio-flexible conductive material according to claim 1, characterized in that, The photoforming includes photoforming technology based on photocuring or photolithography.

4. The bio-flexible conductive material according to claim 1, characterized in that, The shape includes one or more of the following: linear, sheet-like, and block-like.

5. The bio-flexible conductive material according to claim 1, characterized in that, The bio-flexible conductive material also includes one or more patch layers.

6. The bio-flexible conductive material according to claim 1, characterized in that, The bio-flexible conductive material also includes active functional components.

7. Use of the bio-flexible conductive material according to any one of claims 1-6 in the preparation of bioelectrical interfaces, wherein the bioelectrical interface may optionally include one or more of electroencephalogram (EEG) interfaces, electromyogram (EMG) interfaces, and electrocardiogram (ECG) interfaces.

8. Use of the bio-flexible conductive material according to any one of claims 1-6 in the preparation of bio-conductive materials, wherein the bio-conductive material optionally includes a metal-free flexible electrode.

9. A method for preparing a flexible biological electrode patch, characterized in that, Including the following steps: S101, a layer of liquid hydrogel is provided, and the liquid hydrogel is cured using a photocuring device with a first exposure intensity for a first duration to form a first patch layer; S102, a liquid mixture is coated onto the first patch layer, and the liquid mixture is cured in stages using a photocuring device with a second exposure intensity for a second duration to form a corresponding printed pattern on the first patch layer. The printed pattern consists of at least one electrode, and the width of the input end of the electrode is greater than the width of the electrode body. The mixture is prepared by dissolving polyether F127-diacrylate in a conductive polymer solution, wherein the concentration of polyether F127-diacrylate in the mixture is 10-20% (w / v); the concentration of the conductive polymer in the mixture does not exceed 1.5% (w / v); and the conductive polymer includes: poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid). S103, a layer of liquid hydrogel is further coated on the printed pattern, and the liquid hydrogel is cured using a photocuring device with a third exposure intensity for a third duration; wherein the third duration is shorter than the first duration.

10. The method according to claim 9, characterized in that, S102 includes the following steps: S1021, Obtain the preset printing pattern; S1022, the printing pattern is cut using the area of ​​the photocuring device to obtain multiple unit printing patterns, wherein the area of ​​one unit printing pattern is the same as or similar to the area of ​​the printing area. S1023, Obtain the electrode distribution density of the unit printed pattern, wherein the electrode distribution density = area of ​​electrodes in the area / area; S1024, Select a corresponding curing speed for the multiple unit printing patterns according to the electrode distribution density; wherein, the greater the electrode distribution density, the faster the curing speed of the unit printing pattern; S1025, the multiple unit printed patterns are cured in segments using the corresponding curing speeds.

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