Composite membrane, preparation method therefor and use thereof, and biosensor

Abstract

The embodiments of the present application relate to the technical field of hydrogels, and specifically provide a composite membrane, a preparation method therefor and the use thereof, and a biosensor. The composite membrane comprises a hydrogel base membrane; and a reinforcing rib layer is embedded in the hydrogel base membrane, and the reinforcing rib layer is arranged in the extension direction of the hydrogel base membrane. The reinforcing rib layer comprises several fibers, and the fibers are made of an elastic high-molecular polymer. The thickness of the reinforcing rib layer is 0.1-4.0 μm. By means of a mechanical strengthening effect between the reinforcing rib layer and the hydrogel base membrane, the tensile property, toughness, strength and other mechanical properties of the composite membrane are greatly improved. In addition, the thickness and the mechanical properties of the composite membrane are both taken into consideration, such that the composite membrane has an ultra-thin structure and good mechanical properties and air permeability, and thus long-term continuous monitoring of the composite membrane electronic skin biosensor on human health is achieved.

Description

Composite membrane, preparation method thereof, application and biosensor Technical Field

[0001] The present application belongs to the field of hydrogel technology, and specifically relates to a composite membrane, a preparation method thereof, an application thereof, and a biosensor. Background Art

[0002] Long-term, continuous monitoring of human electrophysiological signals, such as electrocardiogram (ECG), electromyography (EMG), and electroencephalogram (EEG), is crucial for disease prevention, early detection, diagnosis, and treatment. Most instruments and devices that monitor these signals require a connection between biological tissue and electronic systems. However, the inherent differences between soft biological tissue and rigid electronic components significantly impact the compatibility, effectiveness, and stability of these interfaces.

[0003] Hydrogels, due to their similarities to biological tissues and their electrical, mechanical, and biological properties, are among the most ideal materials for next-generation bioelectronic interfaces, providing an effective interface between biological tissues and electronic systems. In recent years, hydrogels have made significant progress in the development of flexible wearable sensors. However, hydrogels still face challenges in achieving both thinness and mechanical properties, as well as susceptibility to dehydration and poor gas diffusion. These issues severely restrict their application in long-term, continuous monitoring of human physiological health.

[0004] To reduce the thickness of hydrogel films, researchers in one prior art method used a template casting method to produce hydrogel films with a thickness of 150 μm. However, the hydrogel films produced by this method had poor air permeability and mechanical properties, were easily torn during transfer, and could not adapt to the dynamic environment of human skin for a long time. In another prior art method, researchers used a simple double-roller coater to extrude a hydrogel coated between two layers of hydrophobic film, resulting in an ultra-thin hydrogel with adjustable thickness and a removable film layer. However, the hydrogel films produced by this method also suffered from poor mechanical properties.

[0005] Summary of the Invention

[0006] The purpose of this application is to provide a composite membrane and its preparation method and application to solve the technical problem of poor mechanical properties of existing ultrathin hydrogel films. At the same time, this application also provides a biosensor that can be used for long-term and continuous monitoring of human health.

[0007] In a first aspect, embodiments of the present application provide a composite membrane comprising a hydrogel base membrane, wherein a reinforcing rib layer is embedded in the hydrogel base membrane, and the reinforcing rib layer is arranged along the extension direction of the hydrogel base membrane;

[0008] The reinforcing rib layer includes a plurality of fibers, and the material of the fibers includes an elastic high molecular polymer;

[0009] The thickness of the reinforcement layer is 0.1 to 4.0 μm.

[0010] The composite membrane of the present application embodiment includes a reinforcing rib layer arranged along the direction in which the hydrogel basement membrane extends. The interaction between the reinforcing rib layer and the hydrogel basement membrane significantly enhances the mechanical properties of the composite membrane, including tensile strength, toughness, and strength. Simultaneously, the fiber material and thickness of the reinforcing rib layer are controlled, allowing the reinforcing rib layer and the hydrogel basement membrane to interact with each other, thereby strengthening the mechanical properties and imparting an ultra-thin structure to the composite membrane while also providing excellent mechanical properties. Furthermore, the thinness of the hydrogel basement membrane contributes to the composite membrane's excellent air permeability.

[0011] In a second aspect, the present invention provides a method for preparing a composite membrane. The method comprises the following steps:

[0012] providing a hydrogel solution and reinforcing ribs;

[0013] Performing a film-forming treatment on the hydrogel solution and the reinforcing ribs to obtain a liquid hydrogel composite film, wherein the reinforcing ribs form a reinforcing rib layer in the hydrogel composite film;

[0014] Performing gelation treatment on the hydrogel composite film to obtain a composite film;

[0015] The reinforcing rib layer includes a plurality of fibers, and the material of the fibers includes an elastic high molecular polymer;

[0016] The thickness of the reinforcement layer is 0.1 to 4.0 μm.

[0017] The liquid hydrogel composite membrane prepared by the composite membrane preparation method of the embodiment of the present application includes a liquid hydrogel membrane layer, and the reinforcing rib layer is arranged along the extension direction of the liquid hydrogel membrane layer. The liquid hydrogel composite membrane is subjected to a gelation treatment, so that the hydrogel solution in the liquid hydrogel membrane layer is gelated and converted from liquid to gel, forming a hydrogel basement membrane, thereby forming a composite membrane structure in which the reinforcing rib layer is embedded in the hydrogel basement membrane. The hydrogel basement membrane and the reinforcing rib layer in the composite membrane prepared by the preparation method play a role in strengthening the membrane layer mechanics, so that the composite membrane has good mechanical properties while having an ultra-thin structure. At the same time, since the preparation method of the present application reduces the film thickness of the composite membrane on the basis of ensuring mechanical properties, the air permeability of the composite membrane is also improved. In addition, since the reinforcing rib layer is easy to be arranged in the hydrogel solution membrane layer, the preparation method has fewer steps, the process conditions are easy to control, the quality of the products produced in batches is similar, and the quality repeatability and stability are good.

[0018] In a third aspect, the embodiments of the present application provide applications of the composite film of the embodiments of the present application in biosensors, electronic skin, and flexible electronic devices.

[0019] Based on the embodiments of the present application, the composite membrane can simultaneously possess the advantages of thin membrane layer, good mechanical properties and good air permeability, so that when the composite membrane is used in biosensors, electronic skin, and flexible electronic devices, it has good stability, high comfort, and can be used continuously for a long time.

[0020] In a fourth aspect, embodiments of the present application provide a biosensor comprising the composite membrane of the embodiments of the present application.

[0021] The biosensor in the present embodiment connects the electronic system and biological tissue via the composite membrane described above. The composite membrane's excellent mechanical properties, such as flexibility and tensile strength, enhance its compatibility with biological tissue, thereby improving the stability of the biosensor-tissue interface. Furthermore, the composite membrane's thinness and good air permeability enhance the comfort of the biosensor during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] FIG1 is a schematic diagram of the composite membrane structure provided in an embodiment of the present application;

[0024] FIG2 is a process flow chart of a composite membrane preparation method provided in an embodiment of the present application;

[0025] FIG3 is a process flow chart for preparing the composite membrane provided in Example 1;

[0026] FIG4 is a SEM image of the nanomesh of Example 3;

[0027] FIG5 is a SEM image of the composite film of Example 1 after freeze drying;

[0028] FIG6 is a schematic diagram of the skin compliance test results of the composite film of Example 1;

[0029] FIG7 is an SEM image of the thickness of the composite films of Examples 1 to 3;

[0030] FIG8 is a schematic diagram showing the thickness test results of the composite films of Examples 1 to 3 and the hydrogel basement membrane of Comparative Example 1;

[0031] FIG9 is a schematic diagram showing the tensile properties test results of the composite films of Examples 1 to 3, the hydrogel-based film of Comparative Example 1, and the reinforcing ribs of Example 1;

[0032] FIG10 is a schematic diagram showing the anti-drying performance test results of the composite films of Example 1 and Example 12;

[0033] FIG11 is a schematic diagram showing the gas permeability test results of the composite membrane of Example 1;

[0034] FIG12 is a schematic diagram showing the adhesion energy per unit area test results of the composite films of Examples 1 to 3;

[0035] Figure 13 is a schematic diagram of ECG signal monitoring using the composite membrane and commercial gel in Example 1, wherein A is a schematic diagram of skin contact impedance results, B is a schematic diagram of monitoring sites, C is a schematic diagram of ECG signal monitoring results using the commercial electrode and composite membrane; D is a schematic diagram of ECG signal monitoring results using the composite membrane at different times of continuous monitoring, and E is a schematic diagram of the signal-to-noise ratio of ECG monitoring using the commercial electrode and composite membrane;

[0036] Figure 14 is a schematic diagram of myoelectric signal monitoring of the composite membrane and commercial gel in Example 1, wherein A is a schematic diagram of the monitoring site, and B is a schematic diagram of the monitoring results of the myoelectric signal;

[0037] FIG15 is a schematic diagram of monitoring myoelectric signals generated by stimulation, wherein A is a schematic diagram of the stimulation site and the monitoring site, and B is a schematic diagram of the monitoring results of the myoelectric signals generated by stimulation;

[0038] FIG16 is a schematic diagram of electrooculogram signal monitoring, wherein A is a schematic diagram of the monitoring site, and B is a schematic diagram of the electrooculogram signal monitoring results;

[0039] FIG17 is a schematic diagram of EEG signal monitoring, wherein A is a schematic diagram of the monitoring site, and B and C are schematic diagrams of the EEG signal monitoring results. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0041] In this application, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0042] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0043] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0044] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0045] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass described in the examples of this application may be a mass unit known in the chemical industry, such as μg, mg, g, kg, etc.

[0046] Hydrogels are widely used in medical devices as interfaces connecting electronic systems to biological tissues due to their tissue-like softness, natural biocompatibility, flexibility, and ionic conductivity. Existing hydrogel films suffer from technical issues such as inability to balance thickness and mechanical properties, as well as poor air permeability, resulting in poor hydrogel interface stability, which severely limits their application in long-term biosignal monitoring. To overcome these limitations of existing hydrogels, this application proposes the following embodiments.

[0047] In a first aspect, embodiments of the present application provide a composite membrane. In some embodiments, the structure of the composite membrane of the present application is shown in FIG1 , which includes a hydrogel basement membrane 1, and a reinforcing rib layer 2 embedded in the hydrogel basement membrane 1, and the reinforcing rib layer 2 is arranged along the extension direction of the hydrogel basement membrane 1;

[0048] The reinforcing rib layer 2 includes a plurality of fibers, and the material of the fibers includes an elastic high molecular polymer;

[0049] The thickness of the rib layer 2 is 0.1 to 4.0 μm.

[0050] The composite membrane of the present invention is provided with a reinforcing rib layer 2 extending in the direction of the hydrogel basement membrane 1. The mechanical strength of the composite membrane is enhanced through interaction between the hydrogel basement membrane 1 and the reinforcing rib layer 2. Furthermore, by controlling the fiber material of the reinforcing rib layer 2 and the thickness of the reinforcing rib layer 2 within specific ranges, the composite membrane of the present invention has an ultra-thin structure while exhibiting excellent mechanical properties.

[0051] It should be noted that the thickness of the reinforcing rib layer 2 refers to the thickness of the reinforcing rib layer 2 along the thickness direction of the composite membrane.

[0052] In some embodiments, the thickness of the reinforcing rib layer 2 can be typical but non-limiting thicknesses such as 0.2 μm, 0.6 μm, 1.1 μm, 1.5 μm, 1.8 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, and 4.0 μm. By controlling the thickness of the reinforcing rib layer 2 within this range, the composite film can be formed into an ultra-thin structure while also having good mechanical properties.

[0053] In some embodiments, the fibers in the reinforcing rib layer 2 may be interwoven to form a network structure. In other embodiments, the fibers in the reinforcing rib layer 2 may be parallel to each other and not in contact with each other. For example, the fibers in the reinforcing rib layer 2 may be parallel to each other or arranged in a spiral in the same plane.

[0054] In some embodiments, the morphology of the network structure formed by the interwoven fibers can be regular or irregular. For example, in some embodiments, the network structure can be a regular fishnet-like structure, a honeycomb structure, or an irregular non-woven fabric structure. The reinforcing rib layer 2 is arranged into a network structure and embedded in the hydrogel basement membrane 1. The interaction between the reinforcing rib layer 2 and the hydrogel basement membrane 1 improves the tensile strength and tensile properties of the composite membrane, effectively reducing the tendency of the hydrogel basement membrane 1 to break when stretched alone.

[0055] In some embodiments, the network structure of the reinforcing rib layer 2 can be a single layer or multiple layers. In further embodiments, when the network structure of the reinforcing rib layer 2 is multiple layers, the multiple layers can be independent of each other and not connected to each other, or can be connected to each other or interwoven with each other.

[0056] In some embodiments, the diameter of a single fiber can be 180 to 1600 nm, and further, the diameter of a single fiber can be 200 to 1500 nm. In specific examples, the diameter of the fiber can be 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, 1500 nm, and other typical but non-limiting diameters. Controlling the diameter of the fiber within this range reduces the thickness of the reinforcing rib layer 2, thereby further reducing the thickness of the composite membrane. At the same time, controlling the diameter of the fiber can also make the reinforcing rib layer 2 have better mechanical properties such as toughness and elasticity, thereby further improving the mechanical properties such as flexibility and tensile properties of the composite membrane. It should be noted that the diameter of the fiber in the embodiment of the present application refers to the average diameter of the fiber. For example, the diameter of the fiber is 800nm~1000nm, which means that the average diameter of the fiber in the reinforcing rib layer 2 is in the range of 800nm~1000nm, but not all fiber diameters in the reinforcing rib layer 2 need to be in the range of 800nm~1000nm.

[0057] In some embodiments, the density of the reinforcement layer 2 can be 0.1 to 3.6 mg / cm 2 In a further embodiment, the density of the reinforcing rib layer 2 can be 0.2-1.0 mg / cm 2 In a specific example, the density of the reinforcing rib layer 2 can be 0.1 mg / cm 2 , 0.2mg / cm 2 , 0.3mg / cm 2 , 0.35mg / cm 2 , 0.4mg / cm 2 , 0.5mg / cm 2 , 0.6mg / cm 2 , 0.8mg / cm 2 , 1.0mg / cm 2 , 2.0mg / cm 2 、3.0mg / cm 2 、3.6mg / cm 2 Typical but non-limiting densities are shown. Controlling the density of the reinforcing rib layer 2 within this range further balances the elasticity and strength of the reinforcing rib layer 2, ensuring that the reinforcing rib layer 2 has both good elasticity and suitable strength, thereby further improving the tensile properties of the composite film and providing the composite film with higher strength.

[0058] In some embodiments, the elastic polymer may include at least one of polyurethane (Thermoplastic Polyurethane, TPU), styrene-butadiene-styrene elastomer (Styreneic Block Copolymers, SBS), hydrogenated styrene-butadiene block copolymer (Styrene Ethylene Butylene Styrene, SEBS), polyethylene terephthalate (PET), poly (lactic-co-glycolic acid copolymer) (PLGA), polyethyleneimine (Poly (ethylenimine) PI), poly (vinylidene fluoride) (PVDF). These polymer materials have good elasticity and toughness, and the fibers formed have good toughness and flexibility and are not easy to break when stretched, so that the reinforcing rib layer 2 can effectively interact with the hydrogel basement membrane 1, thereby improving the tensile properties and flexibility of the composite membrane. It should be noted that the material of these fibers can be a single polymer compound or a plurality of polymer compounds, for example, TPU and SBS, and the specific material can be adjusted according to actual needs.

[0059] In some embodiments, the hydrogel basement membrane 1 may include water and a matrix, wherein the matrix may be a temperature-reversible substance, and the matrix's aqueous solution is in a fluid solution state. At the operating temperature or storage temperature, the matrix's aqueous solution is in a warm gel state. Of course, the matrix's aqueous solution may be liquid at high temperatures (e.g., above 50° C.) and gel at low temperatures (e.g., below 50° C.).

[0060] In a further embodiment, the matrix may include at least one of gelatin, carrageenan, locust bean gum, and guar gum. The hydrogel formed by these matrices is in a gel-like state at room temperature and at a temperature close to body temperature. As a result, when the composite film is applied to electronic skin, biosensors, physiological electrical signal instruments (such as electrocardiographs), etc., and under storage conditions, the hydrogel base film 1 can maintain a stable gel state without liquefaction, so as to maintain the morphology of the composite film stable. Of course, the matrix may include one compound, such as only gelatin, or may include multiple compounds, such as the matrix may include gelatin and carrageenan, which can be adjusted according to actual needs. In addition, these matrices give the hydrogel base film 1 a microporous structure, so that the composite film has good air permeability.

[0061] In some embodiments, when the matrix includes gelatin, it may include type A gelatin. Type A gelatin has high transparency, which makes the composite film have good transparency. In addition, the aqueous solution of type A gelatin has good fluidity, which can further improve the uniformity of the film thickness of the composite film.

[0062] In some embodiments, the content of the matrix in the hydrogel basement membrane 1 can be 2-15%, based on the mass of the hydrogel basement membrane 1 being 100%. In further exemplary embodiments, the content of the matrix can be 5-10%. In specific exemplary embodiments, the content of the matrix can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, and other typical but non-limiting contents. Controlling the content of the matrix in the hydrogel basement membrane 1 within this range allows the hydrogel basement membrane 1 to have an appropriate modulus, improves the structural stability of the hydrogel basement membrane 1 in the composite membrane, makes it difficult for the hydrogel basement membrane 1 to separate from the reinforcing rib layer 2, and allows the composite membrane to have better flexibility.

[0063] In some embodiments, the hydrogel basement membrane 1 may further include a water-retaining agent. In further embodiments, the mass content of the water-retaining agent may be 0-30%, based on the mass of the hydrogel basement membrane 1 being 100%. In further embodiments, the water-retaining agent content may be 20-30%. Specific examples include typical but non-limiting content such as 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, and 30%. The addition of the water-retaining agent and the control of its content provide the hydrogel basement membrane 1 with long-term resistance to water loss and drying.

[0064] In some embodiments, the water-retaining agent may include at least one of an alcohol compound, a highly hydrated salt, and an anionic surfactant. These water-retaining agents have excellent water-retaining properties and can effectively retain moisture in the hydrogel basement membrane 1, preventing the hydrogel basement membrane 1 from drying out and dehydrating. Furthermore, these water-retaining agents are not easily decomposed or ineffective, and have excellent stability and durability, capable of retaining moisture in the hydrogel basement membrane 1 for a long time.

[0065] In some embodiments, the alcohol compound may include at least one of glycerol, ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol. These alcohol compounds contain a large number of hydrophilic groups such as hydroxyl groups and have good water retention properties. In addition, these alcohol compounds are miscible with water or have good solubility in water, forming a stable dual solvent system with water, thereby effectively reducing the loss of water in the hydrogel basement membrane 1.

[0066] In some embodiments, the highly hydrated salt may include lithium chloride, which forms a highly hydrated salt with the moisture in the hydrogel basement membrane 1 , thereby effectively retaining the moisture in the hydrogel basement membrane 1 .

[0067] In some embodiments, the anionic surfactant may include Türkiye Red Oil.

[0068] In some embodiments, the hydrogel basement membrane 1 may further include a crosslinking agent, which may include at least one of sodium tetraborate, sodium citrate, and tannic acid. By adding the crosslinking agent, the matrix molecules and the water-retaining agent molecules are crosslinked, thereby increasing the phase transition temperature of the hydrogel basement membrane 1 and the mechanical properties of the composite membrane. For example, in a specific example, glycerol and gelatin can be crosslinked with sodium tetraborate to increase the phase transition temperature, so that the gelatin aqueous solution can be converted into a gel state at a higher temperature, thereby allowing the hydrogel basement membrane 1 to maintain a good gel state at the human body surface temperature (e.g., 37°C), reducing the possibility of the hydrogel basement membrane 1 losing its gel state during use or storage.

[0069] In some embodiments, the mass content of the crosslinker can be 0-5%, based on the mass of the hydrogel basement membrane 1 being 100%. In further embodiments, the crosslinker content can be 3-4.5%. In specific examples, the crosslinker content can be 1%, 2%, 3%, 3.5%, 4%, 4.5%, 5%, and other typical but non-limiting amounts. Controlling the crosslinker content within this range, on the one hand, increases the phase inversion temperature of the hydrogel, further reducing the possibility of the hydrogel basement membrane losing its gel state during use. On the other hand, it can reduce the possibility of excessive crosslinking between molecules such as the matrix and the moisturizer in the hydrogel due to excessive addition of crosslinker, which can affect the tensile properties of the composite membrane. Therefore, the tensile properties of the composite membrane can be further improved.

[0070] In some embodiments, the hydrogel base film 1 may further include a conductive agent. By adding the conductive agent, the hydrogel base film 1 is given conductivity, and thus the composite film is given conductivity, so that the composite film can be used for monitoring bioelectricity.

[0071] In some embodiments, the conductive agent may include a water-soluble ionic compound. In further embodiments, the conductive agent may include water-soluble sulfates, chlorides, and nitrates. In specific examples, the conductive agent may include at least one of sodium sulfate, sodium chloride, sodium nitrate, potassium sulfate, sodium acetate, potassium chloride, and potassium nitrate. Using a water-soluble ionic compound conductive agent allows the conductive agent to dissociate within the hydrogel basement membrane 1, thereby rendering the hydrogel basement membrane 1 transparent. Furthermore, the amount of insoluble particles within the hydrogel basement membrane 1 is reduced, thereby further reducing the thickness of the hydrogel basement membrane 1.

[0072] In some embodiments, the conductive agent may be a water-soluble sulfate. Sulfate radicals can improve the tensile properties of the hydrogel base film 1, thereby further improving the tensile properties of the composite film.

[0073] Of course, when the requirements for the light transmittance or transparency of the hydrogel base film 1 and the adhesion performance of the composite film are not high, the conductive agent can also include non-ionic conductive agents such as carbon nanotubes, graphite, nano silver powder, etc.

[0074] In some embodiments, the mass content of the conductive agent can be 0-3% based on the mass of the hydrogel basement membrane 1 being 100%. Furthermore, the content of the conductive agent can be 1-3%. Specific examples include typical but non-limiting content such as 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, and 3%. Controlling the content of the conductive agent prevents precipitation of the conductive agent, thereby ensuring good conductivity of the hydrogel basement membrane 1 while reducing the effect of the conductive agent on the adhesion properties of the composite membrane.

[0075] In some embodiments, based on the above embodiments of the reinforcing rib layer 2 and the hydrogel base film 1, the fibers in the reinforcing rib layer 2 in the composite film can be interwoven to form a fiber mesh, the fiber diameter can be 900 nm, and the density of the reinforcing rib layer 2 can be 0.1 to 3.6 mg / cm 2 The hydrogel base film 1 in the composite film may include a matrix with a content of 2 to 15%, a water-retaining agent with a content of 0 to 30%, a cross-linking agent with a content of 0 to 5%, and a conductive agent with a content of 0 to 3%. The matrix is ​​gelatin, the water-retaining agent is glycerol, the cross-linking agent is sodium tetraborate, and the conductive agent is sodium sulfate.

[0076] In a further embodiment, the density of the reinforcing rib layer 2 can be 0.2-1.0 mg / cm 2 The matrix content in the hydrogel basement membrane 1 may be 5 to 10%, the water retaining agent content may be 20% to 30%, the cross-linking agent content may be 3 to 4.5%, and the conductive agent content may be 1 to 3%.

[0077] By controlling the fiber material, density, thickness, and morphology of the reinforcing rib layer 2, and by controlling the content of each component in the hydrogel basement membrane 1 within this range, the composite membrane maintains excellent mechanical properties even at an ultra-thin thickness. This also results in excellent air permeability, water retention, and adhesion, enabling the composite membrane to exhibit good skin conformity and comfort when used in biosensors. Furthermore, the composite membrane's long-term water retention ensures long-term stability when used as an interface between biological tissue and electronic systems.

[0078] In some embodiments, the composite film may have a thickness of 10 to 200 μm. In further embodiments, the composite film may have a thickness of 10 to 40 μm. Specifically, the composite film may have a thickness of 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, 200 μm, or other typical but non-limiting thickness ranges. Composite films within these thickness ranges further enhance comfort during use and effectively avoid a heavy feeling during use.

[0079] In some embodiments, the air permeability of the composite membrane can be 0.1 to 3.0 kg m -2 d -1 In a further exemplary embodiment, the air permeability of the composite membrane can be 1.8 to 2.7 kg m -2 d -1 .

[0080] In some embodiments, the tensile properties of the composite film may be 450% to 800%, and the tensile properties of the composite film may be 483% to 606%.

[0081] In some embodiments, the components of the hydrogel-based composite membrane can be controlled to achieve excellent water retention. After 1 to 21 days of storage, the composite membrane can have a water retention rate of over 90%. Furthermore, after 21 days of storage, the composite membrane can have a water retention rate of over 99%. In specific examples, after 21 days of storage, the composite membrane can have a water retention rate of 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%.

[0082] The composite film also has good adhesion. In some embodiments, the adhesion energy per unit area of ​​the composite film is 20 to 200 μJ / cm 2 In a further embodiment, the adhesion energy per unit area of ​​the composite film is 58.3 to 177 μJ / cm 2 .

[0083] Based on the good water retention and good adhesion properties of the composite membrane, the composite membrane can establish a stable and lasting connection with the skin, thereby improving the effectiveness and stability of the interface between the physiological signal monitoring device and the skin.

[0084] In a second aspect, the present invention provides a composite membrane preparation method. In conjunction with FIG1 , the process flow of the composite membrane preparation method of the present invention is shown in FIG2 . The composite membrane preparation method of the present invention includes the following steps:

[0085] Step S01: providing a hydrogel solution and reinforcing ribs;

[0086] Step S02: performing a film-forming process on the hydrogel solution and the reinforcing ribs to obtain a liquid hydrogel composite film, wherein the reinforcing ribs form a reinforcing rib layer in the hydrogel composite film;

[0087] Step S03: performing gelation treatment on the hydrogel composite membrane to obtain a composite membrane;

[0088] The reinforcing rib layer includes a plurality of fibers, and the material of the fibers includes an elastic high molecular polymer;

[0089] The thickness of the reinforcement layer is 0.1 to 4.0 μm.

[0090] The preparation method of the embodiment of the present application is to form a film by treating the hydrogel solution and the reinforcing ribs so that the hydrogel solution forms a liquid hydrogel solution film layer, and the reinforcing ribs form a reinforcing rib layer 2 embedded in the hydrogel solution film layer to form a liquid hydrogel composite film. The hydrogel solution film layer is transformed from a liquid state to a gel state by gelation to form a hydrogel basement membrane 1, thereby forming a composite membrane, and the reinforcing rib layer 2 is embedded in the hydrogel basement membrane 1. In the composite membrane, the reinforcing rib layer 2 and the hydrogel basement membrane 1 play a mechanical strengthening role, so that the composite membrane can have good mechanical properties while having an ultra-thin structure. In addition, the preparation method of the embodiment of the present application has few process steps, easy-to-control process conditions, strong operability, easy to carry out batch production, and good repeatability of product quality.

[0091] Furthermore, the breathability of the composite membrane is related to the thickness of the hydrogel basement membrane 1. Under the same conditions, the thinner the hydrogel basement membrane 1, the better the breathability of the composite membrane. Because the composite membrane can form an ultrathin structure with excellent mechanical properties, the hydrogel basement membrane 1 in the composite membrane can also have an ultrathin structure, thereby enabling the composite membrane to have excellent breathability.

[0092] Step S01:

[0093] The reinforcing ribs provided in step S01 are used to form the reinforcing rib layer 2 contained in the composite membrane of the embodiment of the present application described above. The structure, material, morphology, and thickness of the reinforcing ribs are the same as the structure, material, morphology, and thickness of the reinforcing rib layer 2 described above. In order to save space, the structure and material of the reinforcing ribs will not be described in detail here.

[0094] In some embodiments, the reinforcing ribs can be prepared using an electrospinning method. The reinforcing ribs prepared by these methods can adjust the diameter of the fibers according to actual needs. At the same time, the fibers obtained by electrospinning have good uniformity in thickness, which in turn makes the reinforcing ribs uniform, further improving the uniformity of the composite film obtained. Of course, reinforcing ribs can also be prepared by other methods such as meltblowing.

[0095] The hydrogel solution provided in step S01 is used to form the hydrogel base film 1 contained in the composite film of the above-mentioned embodiment. The content of each component in the hydrogel solution refers to the content of each component in the hydrogel base film 1 contained in the composite film of the above-mentioned embodiment.

[0096] In some embodiments, the temperature of the hydrogel solution can be 50-80°C. By controlling the temperature of the hydrogel solution within this range, the hydrogel solution can remain stably in liquid form and have good film-forming properties, which is conducive to forming a hydrogel solution film layer and facilitating the arrangement of reinforcing ribs in the hydrogel film layer.

[0097] Step S02:

[0098] In step S02, the hydrogel solution and the reinforcing ribs are subjected to film-forming treatment, so that the hydrogel solution forms a liquid hydrogel film layer, and the reinforcing ribs form a reinforcing rib layer 2 embedded in the liquid hydrogel film layer, thereby preparing a liquid hydrogel composite film.

[0099] In some embodiments, in step S02, the hydrogel solution and the reinforcing ribs can be subjected to film-forming treatment by dipping, spraying, brushing, or molding. For example, in a specific example, when the reinforcing ribs are nanofiber networks and dipping is used to form a liquid hydrogel film layer, the reinforcing ribs can be immersed in the hydrogel solution and taken out, and the hydrogel solution forms a liquid hydrogel film layer hanging on the fiber mesh, and the reinforcing rib fiber mesh forms a reinforcing rib layer 2 embedded in the hydrogel film layer. The hydrogel composite film formed by dipping can improve the uniformity of the thickness of the hydrogel film layer on both sides of the reinforcing rib layer 2, and further promote the uniform distribution of the hydrogel film layer on both sides of the reinforcing rib layer 2. In addition, the thickness of the hydrogel film layer can be adjusted by adjusting the fiber diameter, thickness, network structure, and density of the reinforcing rib layer 2.

[0100] Step S03:

[0101] In step S03, the liquid hydrogel composite membrane obtained in step S02 is subjected to a gelation treatment, so that the liquid hydrogel film layer contained therein is transformed from a liquid state to a gel state, forming a hydrogel base membrane 1, thereby obtaining a composite membrane. This composite membrane is the composite membrane described above and will not be described in detail here.

[0102] In some embodiments, the gelation of the hydrogel composite membrane can be achieved by cooling. By lowering the temperature of the hydrogel composite membrane, the liquid hydrogel film layer in the hydrogel composite membrane is gelated to form a gel-state hydrogel basement membrane 1, thereby producing the composite membrane. For example, the hydrogel composite membrane can be cooled to room temperature to cause the liquid hydrogel solution film layer to gel, thereby forming a gel-state hydrogel basement membrane 1. The cooling process of the gelation treatment can be performed with the aid of cooling equipment or by natural cooling. This eliminates the need for additional cooling equipment, reduces energy consumption during the gelation treatment, and further reduces the production cost of the composite membrane preparation method according to the present application.

[0103] In some embodiments, the gelation treatment temperature can be 0-35°C. By controlling the gelation temperature within this range, the liquid hydrogel solution in the hydrogel composite film can be rapidly gelated to form a hydrogel base film 1, thereby preparing a composite film and improving the preparation efficiency of the composite film.

[0104] In a third aspect, the embodiments of the present application provide applications of the above-mentioned composite film in biosensors, electronic skin, and flexible electronic devices.

[0105] Based on the good air permeability, anti-drying, mechanical properties and skin compliance of the above-mentioned composite membrane, the composite membrane has broad application prospects in biosensors, electronic skin and skin electrodes.

[0106] In some embodiments, the flexible electronic device may be an electronic device such as a skin electrode for monitoring physiological electrical signals.

[0107] In a fourth aspect, an embodiment of the present application provides a biosensor comprising the above-mentioned composite membrane.

[0108] The biosensor embodiment of the present application also includes an electronic system. The composite membrane of the present application embodiment can effectively connect the electronic system and biological tissue, particularly skin tissue. Because the composite membrane has excellent air permeability, dryness resistance, tensile properties, flexibility, adhesion, and skin compliance, it enables the biosensor embodiment of the present application to establish a good, effective, and stable connection with the biological tissue. Due to the excellent properties of the composite membrane in all aspects, the biosensor is comfortable to use, avoiding skin redness and swelling caused by long-term use.

[0109] The following uses a number of specific embodiments to illustrate the composite membrane of the present application, its preparation method, application, sensor, etc.

[0110] Example 1

[0111] This embodiment provides a composite membrane comprising a hydrogel-based membrane and reinforcing ribs disposed within the hydrogel-based membrane. The reinforcing rib layer comprises interwoven fibers, wherein the reinforcing rib layer has a thickness of 0.2 μm, the fibers are made of TPU, and have a diameter of 900 nm. The components of the hydrogel-based membrane are shown in Table 1 below.

[0112] As shown in FIG3 , the preparation process of the composite membrane is as follows:

[0113] Step S1, preparation of reinforcing ribs. TPU manufactured by BASF, model 1815A, was dissolved in a mixture of N,N-dimethylformamide (DMF) and tetrahydrofuran (THF) at a mass ratio of 1:1 to prepare an electrospinning solution with a TPU concentration of 13 wt%. The electrospinning solution was loaded into a 5 mL syringe (27G needle) and electrospun at 11 kV to obtain a density of 0.27 mg / cm 2 The nano-mesh is used as a reinforcement, and the fiber diameter of the reinforcement is 900nm.

[0114] Step S2: Preparation of conductive hydrogel solution:

[0115] Appropriate amounts of gelatin, glycerol, sodium tetraborate, and sodium sulfate were dissolved in water to prepare a hydrogel solution. The hydrogel solution was then allowed to stand at 75°C for 2 hours to remove air bubbles. The mass fractions of the components in the hydrogel solution are shown in Table 1.

[0116] Step S3: Preparation of a composite membrane. The reinforcing ribs are secured and transferred using a support frame. The ribs are immersed in the hydrogel solution and then removed. A liquid hydrogel film layer is formed by dip-coating the ribs. The reinforcing ribs form a reinforcing rib layer embedded within the hydrogel film layer. The hydrogel film layer and the reinforcing rib layer constitute a liquid hydrogel composite membrane. The hydrogel composite membrane is cooled at room temperature for 2 minutes to gel the liquid hydrogel in the liquid hydrogel film layer, forming a hydrogel basement membrane, thereby producing a composite membrane.

[0117] Examples 2 to 16.

[0118] Examples 2 to 16 each provide a composite membrane. The preparation methods of the composite membranes of Examples 2 to 12 are substantially the same as those of Example 1, with the differences being the thickness and density of the reinforcing ribs, the material and diameter of the fibers, and the composition and content of the hydrogel solution, as shown in Table 1.

[0119] Table 1

[0120] Comparative Example 1

[0121] This comparative example provides a hydrogel basement membrane having the same composition as that of the hydrogel basement membrane in the composite membrane of Example 1. The preparation process of the hydrogel basement membrane of this comparative example is as follows:

[0122] A support frame with a length and width of 2 cm and a thickness of 0.125 mm was immersed in the hydrogel solution of Example 1. The frame was taken out to form a liquid hydrogel film layer on the frame. The hydrogel film layer was cooled at room temperature for 2 minutes to gel the hydrogel film layer, thereby obtaining the hydrogel base film of Comparative Example 1.

[0123] Performance Testing

[0124] The nanomesh prepared in Example 3 was observed under a scanning electron microscope, and the composite membrane prepared in Example 1 was freeze-dried and then observed under a scanning electron microscope. The results are shown in FIG4 and FIG5 .

[0125] As shown in Figure 4, the reinforcing rib layer of Example 3 is a network structure formed by interwoven fibers, with a fiber diameter of approximately 900 nm. As shown in Figure 5, in the composite membrane of Example 1, the fibers in the reinforcing rib layer interweave to form a nanomesh, and the hydrogel basement membrane coats the nanomesh. The hydrogel basement membrane has a porous structure, which imparts excellent air permeability to the hydrogel, and thus to the composite membrane.

[0126] The composite film of Example 1 was cut into 4 cm x 4 cm pieces and applied to the skin to examine its skin conformability. The results are shown in Figure 6. The composite film of Example 1 adhered closely to the skin surface and naturally flexed with the skin under stretching and compression without noticeable wrinkling or shedding, demonstrating good skin conformability.

[0127] The composite films of Examples 1 to 16, as well as the hydrogel-based film of Comparative Example 1, were tested for thickness, tensile properties, desiccation resistance, air permeability, adhesion energy per unit area, and electrical conductivity. The tensile properties of the reinforcing ribs of Example 1 were also measured under the same conditions.

[0128] The thickness was measured using a Bruker probe profilometer (Dektak XT) and a scanning electron microscope.

[0129] Tensile properties were measured using a Mark-10 universal tensile testing machine equipped with a 10N load cell. The sample was placed vertically in the tensile testing machine's fixture, and the left and right sides of the frame were cut with a sharp knife. Stretching was performed at a rate of 10 mm / min, and the stress and strain during stretching were recorded.

[0130] The test method for anti-drying performance is as follows:

[0131] The composite film is taken and its initial weight is determined. The weighed hydrogel is placed under conditions of 25°C and 45-70% RH for a certain period of time (e.g., 7 days, 10 days, etc.), and then weighed again. The anti-drying performance of the composite film is calculated according to the formula shown in formula (1).

[0132] In the formula (1), W represents the anti-drying performance, W0 represents the initial weight of the composite film, and W t represents the weight of the composite film after day t.

[0133] The test method for air permeability is as follows:

[0134] The composite film to be tested was covered on a glass bottle containing 20 g of water and weighed. The glass bottle was placed at 25°C and 30% RH. The weight of the glass bottle was measured every day, and the weight of the water reduced in the glass bottle was calculated. The air permeability of the composite film was calculated according to the formula shown in formula (2).

[0135] The P shown in the above formula (2) represents the air permeability of the composite membrane, and the unit is kg m -2 d -1 , W 水 It represents the weight of water reduced in the glass bottle, in g, and S represents the area of ​​the composite film relative to the bottle mouth, in m 2 , T represents time, the unit is d (day).

[0136] Adhesion performance was determined by a 90° peel test. The sample was attached to the artificial skin surface with an initial attachment area of ​​10 × 10 mm. 2 The adhesion force of the ultrathin hydrogel and artificial skin was recorded at a vertical tensile speed of 20 mm / s using a Mark-10 universal testing machine. The adhesion performance can be calculated using the following formula.

[0137] In the above formula (3), E represents the adhesion energy per unit area of ​​the composite film, and the unit is μJ / cm 2 , y represents the adhesion force, x represents the separation distance, and L represents the distance.

[0138] The thickness, tensile properties, anti-drying properties, air permeability and adhesion properties of the composite films of Examples 1 to 12 and the hydrogel base film of Comparative Example 1, as well as the tensile properties test results of the reinforcing rib of Example 1 are shown in Table 2 and Figures 7 to 12.

[0139] Table 2

[0140] As shown in Table 2 and Figures 7-9, the composite membranes provided in the examples of this application have an ultrathin structure. The composite membrane of Example 1 has a thickness as low as 10 μm, and this thickness can be adjusted according to actual needs. Even at a thickness as low as 10 μm, the composite membrane still exhibits good tensile properties, demonstrating that the composite membranes of the examples of this application achieve a balance between thickness and mechanical properties.

[0141] Compared to the hydrogel-based membrane of Comparative Example 1, the composite membrane of Example 1 has the same thickness and hydrogel components, the only difference being the inclusion of a reinforcing rib layer within the hydrogel-based membrane. As shown in Figure 9, the tensile performance of the composite membrane of Example 1 is 606%, significantly higher than the 364% tensile performance of the hydrogel-based membrane of Comparative Example 1. Furthermore, the tensile performance of the composite membrane of Example 1 is also higher than that of the nanomesh of Example 1. This demonstrates that the tensile performance of the composite membrane of the present application is enhanced not only by the reinforcing rib layer but also through the interaction between the hydrogel-based membrane and the reinforcing rib layer.

[0142] As shown in Table 2 and Figure 10, the ratio of the components in the hydrogel basement membrane of the embodiment of the present application makes the composite membrane of the embodiment of the present application have good anti-drying properties, which can effectively retain the moisture in the hydrogel basement membrane for a long time, providing good conditions for the application of the composite membrane in long-term physiological health testing.

[0143] The composite membranes of the present invention have good air permeability. Furthermore, as shown in Figure 11, the test results of the composite membrane of Example 1 show no significant difference between the uncovered test results and the PDMS-covered control group, which demonstrates that the composite membranes of the present invention have good air permeability.

[0144] The composite films of Examples 1 to 16 have good adhesion properties. As shown in Table 2 and Figure 12, there is no significant difference in the adhesion energy per unit area between the composite film of Example 1 and the hydrogel-based film of Comparative Example 1.

[0145] The composite membrane of the embodiment of the present application has good skin compliance, mechanical properties, anti-drying properties, air permeability and adhesion properties, so that the composite membrane of the present application can maintain good and stable contact with the skin for a long time, enabling its long-term application in electrophysiological signal monitoring.

[0146] Physiological monitoring performance test:

[0147] The composite membrane of Example 1 was used as a biosensor and monitored for electrocardiogram, electromyography, electroencephalography, electrooculography, and somatosensory evoked potential signals under the same conditions as commercial Ag / AgCl hydrogel electrodes from NIHON KOHDEN. The results are shown in Figures 13 to 17 .

[0148] A prerequisite for achieving long-term, high-quality health monitoring is to build a stable, low-impedance interface between the electrode and the skin. Stable and low skin contact impedance can achieve a higher signal-to-noise ratio and more accurate biosignal recording. As shown in A of Figure 13, the skin contact impedance of the composite film of the embodiment of the present application is lower than that of the commercial gel electrode. Under 100Hz conditions, the skin contact impedance of the composite film of the embodiment of the present application is 31.3kΩ, and the skin contact impedance of the commercial gel electrode is 57.5kΩ. Moreover, the skin contact impedance curve of the composite film after continuous wearing for 24 hours is basically consistent with the initial skin contact impedance curve, indicating that the composite film of the embodiment of the present application can provide a long-term, stable connection. Based on the low skin contact impedance, high compliance, mechanical robustness and water retention properties of the composite film of the embodiment of the application, it has the advantages of high comfort, good connection stability and low electrode impedance when used in physiological signal monitoring, and can achieve long-term, high-quality health monitoring.

[0149] Furthermore, as shown in Figure 13, during ECG monitoring, two composite films from Example 1 were placed on the chest of a subject and connected to a portable sensor with a Bluetooth component to capture ECG signals in real time for long-term monitoring. Simultaneously, during the initial phase of ECG signal monitoring using the composite films from Example 1, commercial Ag / AgCl electrodes were used to monitor ECG signals under the same conditions.

[0150] The ECG signals monitored by the composite membrane of the present application example exhibited waveforms similar to those of commercial Ag / AgCl electrodes (signal-to-noise ratio: 29.7±1.0dB), with the composite membrane of the present application example exhibiting an even higher signal-to-noise ratio of 32.8±1.6dB. Due to its long-term water retention, the composite membrane of the present application example displayed high-quality and high-fidelity ECG signals for up to 21 days (the signal-to-noise ratio on day 21 was 29.8±2.0dB, similar to the signal-to-noise ratio during the initial measurement), without causing any negative effects on the skin.

[0151] As shown in Figures 14 to 17, when the embodiments of the present application are applied to the monitoring of physiological signals such as electromyography, electrooculography, electroencephalography and somatosensory evoked potentials, in the initial stage of monitoring, the composite membrane of the embodiments of the present application has a monitoring effect similar to or better than that of commercial gel. In addition, the monitoring effect of the composite membrane of the embodiments of the present application after 24 hours of continuous monitoring is not significantly different from the monitoring effect in the initial stage. The composite membrane of the embodiments of the present application has been successfully applied to the long-term monitoring of physiological signals such as electrocardiography, electromyography, electrooculography, electroencephalography and somatosensory evoked potentials, providing a new method for skin electronic devices, representing an important step towards personalized medicine.

[0152] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A composite film, characterized in that: It comprises a hydrogel base film, and a reinforcing rib layer is embedded in the hydrogel base film, and the reinforcing rib layer is arranged along the extension direction of the hydrogel base film; The reinforcing rib layer includes a plurality of fibers, and the material of the fibers includes an elastic high molecular polymer; The thickness of the reinforcing rib layer is 0.1-4.0 μm.

2. The composite film according to claim 1, characterized in that: The diameter of a single fiber is 180 to 1600 nm; and / or The fibers are interwoven to form a network structure; and / or The density of the reinforcing rib layer is 0.1-3.6 mg / cm 2 ; and / or The elastic high molecular polymer includes at least one of TPU, SBS, SEBS, PET, PLGA, PI and PVDF.

3. The composite film according to any one of claims 1 to 2, characterized in that: Taking the mass of the hydrogel base film as 100%, the hydrogel base film includes water and the following components in percentage by mass:

4. The composite film according to claim 3, characterized in that: The matrix comprises at least one of gelatin, carrageenan, locust bean gum, and guar gum; and / or The water retaining agent comprises at least one of an alcohol compound, a highly hydrated salt, and an anionic surfactant; and / or The cross-linking agent includes at least one of sodium tetraborate, sodium citrate and tannic acid; and / or The conductive agent includes an ionic compound.

5. The composite film according to claim 4, characterized in that: The alcohol compound includes at least one of glycerol, ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol; and / or The highly hydrated salt comprises lithium chloride; and / or The anionic surfactant comprises Türkiye red oil; and / or The ionic compound includes at least one of sodium sulfate, sodium chloride, sodium nitrate, potassium sulfate, sodium acetate, potassium chloride and potassium nitrate.

6. The composite membrane according to any one of claims 1-2, 4-5, characterized in that: The thickness of the composite film is 7 to 200 μm; and / or The tensile strength of the composite film is 450% to 800%; and / or The air permeability of the composite membrane is 0.1 to 3.0 kg m -2 d -1 ; and / or After the composite film is stored for 1 to 21 days, the water retention rate is above 90%; and / or The adhesion energy per unit area of ​​the composite film is 10 to 220 μJ / cm 2 .

7. A method for preparing a composite membrane, characterized in that: The steps include: providing a hydrogel solution and a reinforcing rib; Performing film-forming treatment on the hydrogel solution and the reinforcing ribs to obtain a liquid hydrogel composite film, wherein the reinforcing ribs form a reinforcing rib layer in the hydrogel composite film; Performing gelation treatment on the hydrogel composite film to obtain a composite film; Wherein, the reinforcing rib layer comprises a plurality of fibers, and the material of the fibers comprises an elastic high molecular polymer; The thickness of the reinforcing rib layer is 0.1-4.0 μm.

8. The preparation method according to claim 7, characterized in that: The reinforcing ribs are prepared by an electrostatic spinning method; and / or The temperature of the hydrogel solution is 50-80° C.; and / or The temperature of the gelation treatment is 0-35°C. The gelation time is 2 to 3 minutes.

9. Application of the composite film according to any one of claims 1 to 6 or the composite film prepared by the composite film preparation method according to any one of claims 7 to 8 in biosensors, electronic skin, and flexible electronic devices.

10. A biosensor, characterized in that: The biosensor comprises the composite membrane according to any one of claims 1 to 6 or a composite membrane prepared by the composite membrane preparation method according to any one of claims 7 to 8.

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