A uric acid sensor based on NiCo-BTC composite material and its preparation method

Abstract

This invention relates to the field of detection technology, and provides a uric acid sensor based on NiCo-BTC composite material and its preparation method. The sensor comprises a substrate, an electrode system, a sensing element, and an insulating layer. The sensing element is connected to the electrode system. The sensing element is used to detect the concentration of uric acid molecules in a sample solution and generate a current signal. The electrode system is used to transmit the current. The insulating layer is disposed in the non-working area of ​​the electrode system away from the sensing element, and serves to isolate and protect the electrode system. The sensing element is made of conductive carbon cloth and a NiCo-BTC layer grown in situ on its surface. Using this uric acid sensor can solve problems such as high bulk and interfacial electron transport impedance of existing electrode materials, leading to low charge conduction efficiency; uneven distribution of active sites, resulting in insufficient catalytic activity utilization; significant structural deformation or pulverization of materials under cyclic conditions, resulting in poor mechanical stability and durability; and lengthy or obstructed mass transfer paths between reactants and products, restricting reaction kinetics.

Description

Technical Field

[0001] This invention relates to the field of detection technology, and in particular to a uric acid sensor based on NiCo-BTC composite material and its preparation method. Background Technology

[0002] Uric acid is the end product of purine metabolism in the human body, and its abnormal concentration is closely related to various pathological conditions such as gout, hyperuricemia, kidney damage, and cardiovascular diseases. Therefore, developing rapid, sensitive, and reliable uric acid detection technologies is of great significance for the early diagnosis and dynamic monitoring of diseases. Among various analytical methods, electrochemical sensing technology is considered an ideal platform for point-of-care testing due to its advantages such as simple instrumentation, rapid response, low cost, and ease of miniaturization. The core performance of this technology lies in the electrocatalytic material at the working electrode interface, which must simultaneously meet multiple requirements, including high catalytic activity, strong anti-interference ability, rapid electron conduction, and excellent structural stability.

[0003] In recent years, metal-organic frameworks (MOFs), especially NiCo-BTC with bimetallic synergistic effects, have shown great potential in electrocatalysis due to their ultra-high specific surface area, tunable pore structure, and abundant active sites. Traditional research usually focuses on the catalytic properties of their bulk powders. However, conventional processes prepare MOFs into micron-sized or relatively thick bulk powders, which are then mixed with conductive agents and binders and coated onto the electrode surface. This method has significant inherent drawbacks: First, the thick material dimensions and the use of insulating binders severely hinder the longitudinal transport of electrons from the internal active sites to the electrode substrate and cover some active sites, leading to a reduction in intrinsic catalytic efficiency. Second, the physical coating layer has weak adhesion and is prone to peeling off after long-term use, seriously affecting the stability and reproducibility of the sensor. Finally, the excessively thick material dimensions and random stacking significantly prolong the mass transfer path, limiting reaction kinetics. Summary of the Invention

[0004] The purpose of this invention is to address the following problems in existing electrode materials: high bulk and interfacial electron transport impedance leading to low charge conduction efficiency; uneven distribution of active sites resulting in insufficient utilization of catalytic activity; significant structural deformation or pulverization of materials under cyclic conditions, resulting in poor mechanical stability and durability; and lengthy or obstructed mass transfer paths between reactants and products, which restrict reaction kinetics. This invention provides a uric acid sensor based on NiCo-BTC composite material and its preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A uric acid sensor based on NiCo-BTC composite material includes a substrate, an electrode system fabricated on the substrate, and a sensing element. The sensing element is electrically connected to the electrode system. The sensing element is used to detect the concentration of uric acid molecules in a sample solution and generate a current signal. The electrode system is used for current conduction.

[0007] The sensing element is made of NiCo-BTC@CC composite material, which includes conductive carbon cloth and a NiCo-BTC layer grown in situ on the surface of its fibers.

[0008] The present invention provides a uric acid sensor based on NiCo-BTC composite material. The NiCo-BTC composite material has a through-hole multi-level pore structure, which provides a fast and unobstructed diffusion path for uric acid molecules, ensuring efficient contact and utilization of active sites, improving the reaction rate, and enabling the sensor to have a faster response time.

[0009] The NiCo-BTC composite material uses the conductive carbon cloth with three-dimensional porosity as a self-supporting and highly conductive substrate material, effectively reducing charge transfer impedance. The synergistic effect of the Ni and Co bimetallic nodes in the NiCo-BTC layer and the extended conjugated structure constructed by organic ligands significantly improve the material's electronic conductivity. The NiCo-BTC layer has an extremely high specific surface area, achieving high dispersion and full exposure of catalytic active sites, exhibiting high sensitivity and low overpotential for the uric acid oxidation reaction. The NiCo-BTC layer material has a stable framework structure, and through in-situ growth on the conductive carbon cloth, it possesses excellent mechanical stability and structural durability, ensuring stable response signals during long-term monitoring or continuous cyclic testing, significantly extending the sensor's lifespan.

[0010] If ultrathin (e.g., 4-5 nm) NiCo-BTC nanosheet arrays can be grown directly and in situ on the surface of carbon fiber, it will revolutionize materials and optimize electrode structures. This ultrathin nanosheet structure has revolutionary advantages: firstly, its 4-5 nm thickness is comparable to the Debye length of electrons / ions, enabling near-unimpeded rapid lateral and longitudinal charge transport, significantly reducing internal resistance; secondly, its ultrathin nature exposes almost all metal active sites on the surface, making them easily accessible and significantly improving atomic utilization and intrinsic activity. This integrated "material-electrode" system, constructed through precise nanoscale thickness control and in-situ growth, is expected to synergistically enhance charge transport, mass transfer, and active site exposure, thereby simultaneously overcoming existing limitations in sensor sensitivity, response speed, and stability.

[0011] As a preferred embodiment of the present invention, the microstructure of the NiCo-BTC layer is a NiCo-BTC nanosheet array.

[0012] The NiCo-BTC nanosheets grow vertically on the conductive carbon cloth, forming an open and ordered mesoscopic structure, which greatly promotes the rapid penetration of electrolytes and the diffusion of uric acid molecules.

[0013] As a preferred embodiment of the present invention, the thickness of the NiCo-BTC nanosheet is 4-5 nm.

[0014] The thickness of the NiCo-BTC nanosheets is comparable to the Debye length of electrons / ions, enabling rapid lateral charge transport and longitudinal penetration, greatly reducing internal resistance. The ultrathin nature of the NiCo-BTC nanosheets exposes almost all metal active sites on the surface and makes them easily accessible, significantly improving atomic utilization and intrinsic activity.

[0015] As a preferred embodiment of the present invention, the electrode system includes a working electrode, a counter electrode and a reference electrode, and the sensing element is electrically connected to the working electrode.

[0016] As a preferred embodiment of the present invention, the substrate material comprises polyethylene terephthalate, polyimide, or polyvinyl butyral.

[0017] A method for fabricating a uric acid sensor based on NiCo-BTC composite material, comprising the following steps:

[0018] S1. Clean and acid-etch the conductive carbon cloth.

[0019] S2. Using cobalt nitrate and nickel nitrate as metal sources and pyromellitic acid as an organic ligand, a NiCo-BTC layer is grown on the surface of the conductive carbon cloth to obtain the NiCo-BTC@CC composite material.

[0020] S3. Sequentially fabricate the working electrode, counter electrode, and reference electrode on the top surface of the substrate;

[0021] S4. Connect the NiCo-BTC@CC composite material to the working electrode using conductive silver paste, and then encapsulate it to obtain a uric acid sensor based on NiCo-BTC composite material.

[0022] This invention provides a method for fabricating a uric acid sensor based on NiCo-BTC composite material, employing a one-step hydrothermal method. The process is simple and reproducible. By adjusting hydrothermal parameters (such as temperature and time), the morphology and thickness of the nanosheets can be effectively controlled, ensuring optimized and consistent sensor performance.

[0023] As a preferred embodiment of the present invention, in step S1, the acid etching process specifically involves: placing the cleaned conductive carbon in a dilute hydrochloric acid solution with a concentration of 0.5-2 mol / L, and etching at 50-80°C for 20-40 minutes.

[0024] As a preferred embodiment of the present invention, step S2 specifically includes the following steps:

[0025] S201. Preparation of precursor solution: Dissolve cobalt nitrate hexahydrate, nickel nitrate hexahydrate and trimesic acid in anhydrous ethanol to obtain a mixed solution;

[0026] S202, Hydrothermal reaction: The conductive carbon cloth pretreated in step S1 is immersed in the precursor solution and placed in a hydrothermal reactor for reaction at 120-180°C for 10-18 hours.

[0027] S203. Post-processing: After the reaction is complete, the carbon cloth loaded with the product is removed, and after cleaning and drying, the NiCo-BTC@CC composite material is obtained.

[0028] As a preferred embodiment of the present invention, the Co in the mixed solution 2+ with Ni 2+ The molar ratio is (0.5-2):1, and the molar ratio of total metal ion concentration to trimesic acid is 1:(0.8-1.2).

[0029] As a preferred embodiment of the present invention, in step S3, the electrode system is prepared by screen printing, inkjet printing or photolithography, the working electrode is a silver electrode, the counter electrode is a carbon electrode, and the reference electrode is an Ag / AgCl electrode.

[0030] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0031] 1. A uric acid sensor based on NiCo-BTC composite material, wherein the NiCo-BTC composite material uses a three-dimensional porous conductive carbon cloth as a self-supporting substrate material with excellent conductivity, effectively reducing charge transfer impedance. The synergistic effect of the Ni and Co bimetallic nodes in the NiCo-BTC layer and the extended conjugated structure constructed by organic ligands significantly improve the electronic conductivity of the material. The NiCo-BTC layer has an extremely high specific surface area, achieving high dispersion and full exposure of catalytic active sites, exhibiting high sensitivity and low overpotential for the uric acid oxidation reaction. The NiCo-BTC layer material has a stable framework structure, which, through in-situ growth on the conductive carbon cloth, has excellent mechanical stability and structural durability, ensuring that the sensor maintains a stable response signal during long-term monitoring or continuous cyclic testing, significantly extending the sensor's service life.

[0032] 2. A method for fabricating a uric acid sensor based on NiCo-BTC composite material, employing a one-step hydrothermal method, which is simple and has good repeatability. By adjusting hydrothermal parameters (such as temperature and time), the morphology and thickness of the nanosheets can be effectively controlled, ensuring the optimization and consistency of sensor performance. Attached Figure Description

[0033] Figure 1 This is a graph showing the linear relationship between the response current and uric acid concentration of a uric acid sensor based on NiCo-BTC composite material.

[0034] Figure 2 The image shows the X-ray diffraction pattern of a NiCo-BTC@CC composite material for a uric acid sensor based on NiCo-BTC composite material.

[0035] Figure 3 This is a scanning electron microscope image of a NiCo-BTC@CC composite material used in a uric acid sensor based on a NiCo-BTC composite material.

[0036] Figure 4 This is a topographic image of a NiCo-BTC@CC composite material used in an atomic force microscope for a uric acid sensor based on NiCo-BTC composite material.

[0037] Figure 5 This is a current response diagram of a uric acid sensor based on NiCo-BTC composite material to various interfering substances;

[0038] Figure 6 This is a long-term stability graph of a uric acid sensor based on NiCo-BTC composite material. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings.

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] Example 1

[0042] like Figure 1 As shown, the uric acid sensor based on NiCo-BTC composite material used in this invention includes a substrate, an electrode system fabricated on the substrate, and a sensing element. The sensing element is electrically connected to the electrode system. The sensing element is used to detect the concentration of uric acid molecules in the sample solution and generate a current signal. The electrode system is used to transmit current.

[0043] The sensing element is made of NiCo-BTC@CC composite material, which includes conductive carbon cloth and a NiCo-BTC layer grown in situ on the surface of its fibers.

[0044] Furthermore, the microstructure of the NiCo-BTC layer is an array of NiCo-BTC nanosheets.

[0045] Furthermore, the thickness of the NiCo-BTC nanosheets is 4-5 nm.

[0046] Furthermore, the electrode system includes a working electrode, a counter electrode, and a reference electrode, and the sensing element is electrically connected to the working electrode.

[0047] Furthermore, the substrate material comprises polyethylene terephthalate, polyimide, or polyvinyl butyral.

[0048] The NiCo-BTC composite material utilizes the three-dimensional porous conductive carbon cloth as a self-supporting and highly conductive substrate, effectively reducing charge transfer impedance. The synergistic effect of the Ni and Co bimetallic nodes in the NiCo-BTC layer and the extended conjugated structure constructed by organic ligands significantly enhance the material's electronic conductivity. The NiCo-BTC layer possesses an extremely high specific surface area, achieving high dispersion and full exposure of catalytic active sites, exhibiting high sensitivity and low overpotential for the uric acid oxidation reaction. The NiCo-BTC layer material has a stable framework structure, and through in-situ growth on the conductive carbon cloth, it exhibits excellent mechanical stability and structural durability, ensuring stable response signals during long-term monitoring or continuous cyclic testing, significantly extending the sensor's lifespan.

[0049] In this embodiment, the counter electrode, the working electrode, and the reference electrode of the uric acid sensor are sequentially and parallelly arranged on the top surface of the substrate. One end of the counter electrode and the reference electrode forms an open, regular shape. One end of the working electrode is disc-shaped and is disposed within the open, regular shape formed by the counter electrode and the reference electrode. The sensing element is circular and electrically connected to the disc end of the working electrode. The insulating layer is disposed on the non-working area of ​​the top surface of the electrode system. The resulting uric acid sensor is denoted as Sensor A.

[0050] Example 2

[0051] The present invention discloses a method for preparing a uric acid sensor based on NiCo-BTC composite material, which prepares a uric acid sensor based on NiCo-BTC composite material as described in Example 1, comprising the following steps:

[0052] S1. Clean and acid-etch the conductive carbon cloth.

[0053] S2. Using cobalt nitrate and nickel nitrate as metal sources and pyromellitic acid as an organic ligand, a NiCo-BTC layer is grown on the surface of the conductive carbon cloth to obtain the NiCo-BTC@CC composite material.

[0054] S3. Sequentially fabricate the working electrode, counter electrode, and reference electrode on the top surface of the substrate;

[0055] S4. Connect the NiCo-BTC@CC composite material to the working electrode using conductive silver paste, and then encapsulate it to obtain a uric acid sensor based on NiCo-BTC composite material.

[0056] Furthermore, in step S1, the acid etching process specifically involves placing the cleaned conductive carbon in a dilute hydrochloric acid solution with a concentration of 0.5-2 mol / L and etching it at 50-80°C for 20-40 minutes.

[0057] Furthermore, in step S2, the specific steps are as follows:

[0058] S201. Preparation of precursor solution: Dissolve cobalt nitrate hexahydrate, nickel nitrate hexahydrate and trimesic acid in anhydrous ethanol to obtain a mixed solution;

[0059] S202, Hydrothermal reaction: The conductive carbon cloth pretreated in step S1 is immersed in the precursor solution and placed in a hydrothermal reactor for reaction at 120-180°C for 10-18 hours.

[0060] S203. Post-processing: After the reaction is complete, the carbon cloth loaded with the product is removed, and after cleaning and drying, the NiCo-BTC@CC composite material is obtained.

[0061] Furthermore, the Co in the mixed solution 2+ with Ni 2+ The molar ratio is (0.5-2):1, and the molar ratio of total metal ion concentration to trimesic acid is 1:(0.8-1.2).

[0062] Furthermore, in step S3, the electrode system is prepared by screen printing, inkjet printing or photolithography, the working electrode is a silver electrode, the counter electrode is a carbon electrode, and the reference electrode is an Ag / AgCl electrode.

[0063] The one-step hydrothermal method is simple and has good repeatability. By adjusting the hydrothermal parameters (such as temperature and time), the morphology and thickness of the nanosheets can be effectively controlled, ensuring the optimization and consistency of sensor performance.

[0064] In this embodiment, the pretreatment of the conductive carbon cloth is as follows: A piece of the conductive carbon cloth with dimensions of 2 cm × 4 cm is taken and ultrasonically cleaned for 15 minutes each in acetone, anhydrous ethanol, and deionized water to thoroughly remove surface organic contaminants and dust. The conductive carbon cloth is then immersed in a 1 mol / L dilute hydrochloric acid solution and etched in a constant temperature water bath at 60°C for 30 minutes. This process effectively removes metal oxide impurities from the surface of the conductive carbon cloth and increases the roughness and hydrophilicity of the fiber surface. After etching, it is rinsed with a large amount of deionized water until neutral and then completely dried in an oven at 60°C. The treated conductive carbon cloth provides a clean substrate with abundant nucleation sites for subsequent uniform crystal growth.

[0065] Preparation of NiCo-BTC@CC composite material: 0.291 g of cobalt nitrate hexahydrate, 0.291 g of nickel nitrate hexahydrate (ensuring a metal ion molar ratio of Co:Ni = 1:1), and 0.210 g of trimesic acid as organic ligands were weighed out. These reagents were dissolved sequentially in 40 mL of anhydrous ethanol and magnetically stirred at room temperature for 1 hour until a homogeneous, clear, pinkish-purple mixed solution was formed, yielding the precursor solution.

[0066] The pretreated conductive carbon cloth was completely immersed in the precursor solution and transferred together to a 50 mL high-pressure hydrothermal reactor lined with polytetrafluoroethylene (PTFE), which was then sealed. The high-pressure hydrothermal reactor was placed in a forced-air drying oven and subjected to a hydrothermal reaction at a constant temperature of 150°C for 14 hours. During this process, metal ions and organic ligands self-assembled on the surface of the conductive carbon cloth fibers, resulting in in-situ crystallization growth to form the NiCo-BTC nanosheet array.

[0067] After the reaction was completed, the hydrothermal reactor was allowed to cool naturally to room temperature. The conductive carbon cloth loaded with the product was removed; its color changed from pure black to light purple. The conductive carbon cloth loaded with the product was then ultrasonically cleaned several times alternately in anhydrous ethanol and deionized water to remove physically adsorbed impurities and loosely attached particles. The conductive carbon cloth loaded with the product was then dried in a vacuum drying oven at 60°C for 5 hours to obtain the NiCo-BTC@CC composite material.

[0068] Fabrication of the flexible sensor substrate: The substrate is prepared using a screen printing process. In this embodiment, the substrate material is PET film. On the substrate, which has undergone plasma cleaning, the working electrode, the counter electrode, and the reference electrode, along with an insulating layer, are sequentially prepared by screen printing to form a standard three-electrode system. The side of the working electrode to be electrically connected to the sensing element adopts a 3 mm diameter exposed silver paste disk structure. After printing, the substrate is heat-treated at 120°C for 20 minutes to solidify the electrode pattern, ensuring good conductivity and adhesion.

[0069] Integration and final assembly of the sensing element: Using a precision drill, a 3 mm diameter disc is cut from the prepared NiCo-BTC@CC composite material. Using the conductive silver paste as an adhesive, a thin layer of the conductive silver paste is applied to the disc structure area of ​​the working electrode using a micro-dispensing device. The conductive carbon cloth side of the cut NiCo-BTC@CC composite material is aligned and attached to the working electrode. Curing is performed at room temperature for 2 hours to fully cure the conductive silver paste, thereby firmly and with low resistance integrating the NiCo-BTC@CC sensing material into the circuit system. The insulating layer is made of epoxy resin and is prepared in the non-working area to obtain a finished uric acid sensor that can be used for direct detection.

[0070] Comparative Example

[0071] A uric acid sensor is substantially the same as the uric acid sensor based on NiCo-BTC composite material prepared in any one of Examples 1 to 2, except that the sensing element is prepared by mixing 2 mg of NiCo-BTC powder with 0.5 mg of conductive carbon black and 20 μL of 0.5 wt% Nafion solution, coating the mixture onto the working electrode and curing it to obtain the uric acid sensor, denoted as sensor B.

[0072] like Figure 1 As shown, scanning electron microscopy reveals that the surface of the conductive carbon fiber of sensor A is completely covered by a uniform and dense array of NiCo-BTC nanosheets. These NiCo-BTC nanosheets are interconnected, forming an open three-dimensional hierarchical porous structure, which greatly increases the specific surface area of ​​the material. Figure 2 As shown, high-resolution transmission electron microscopy and atomic force microscopy tests indicate that the NiCo-BTC nanosheets generated on sensor A are extremely thin, with an average thickness of only 4-5 nm. This provides a rapid diffusion channel for electrolyte ions and is also beneficial for the adsorption and mass transfer of uric acid molecules, thereby improving reaction kinetics and detection sensitivity. Figure 3As shown, X-ray diffraction patterns and structural simulations confirm that the material grown on sensor A has a typical bimetallic MOF crystal structure, in which Ni and Co atoms coordinate with oxygen atoms in the pyromellitic tricarboxylic acid ligand to form a framework with periodic pores, providing an ideal microenvironment for the adsorption and catalysis of uric acid molecules.

[0073] like Figure 4 As shown, sensor A was connected to an electrochemical workstation, and its performance was evaluated in 0.1M phosphate buffer solution at pH 7.4. Differential pulse voltammetry was used for testing. Within the uric acid concentration range of 1 μM to 500 μM, the response current of sensor A showed a linear relationship with the uric acid concentration in the 1–500 μM range. The linear regression equation is as follows: Correlation coefficient R 2 =0.998, sensitivity reaches 1520μA mM -1 cm -2 .

[0074] like Figure 5 As shown, in a test solution containing 100 μM uric acid, 1 mM ascorbic acid, dopamine, glucose, urea, and common ions (such as Na+) were added respectively. + , K + , Cl - Test results show that the current response changes of sensor A caused by various interfering factors are all less than 5% of the response value to uric acid, indicating that sensor A has excellent selectivity.

[0075] like Figure 6 As shown, after storing sensor A in a desiccator at room temperature for 30 days, a retest showed that the DPV response current of sensor A for 100 μM uric acid retained 96.5% of the initial value. This excellent stability stems directly from the in-situ growth technology, which enables a strong chemical / physical bond between the active material and the carbon cloth substrate, avoiding the material detachment problem in traditional drop-coating methods. A standard addition method was used to perform spiked recovery experiments on diluted human urine samples. The recoveries were measured to be between 97.2% and 102.8%, with an RSD of less than 4.2%, verifying the accuracy and reliability of the sensor in detecting complex samples in real-world applications.

[0076] Under the same test conditions, the sensitivity of sensor B (approximately 850 μA mM) -1 cm -2 Both the stability (signal attenuation after continuous testing) and the signal strength are far inferior to those of the A sensor, which confirms that the A sensor with an integrated electrode of ultrathin NiCo-BTC nanosheet structure prepared by the present invention through in-situ growth method is more advantageous.

[0077] In summary, the uric acid sensor based on NiCo-BTC composite material and its preparation method disclosed in this invention have a simple process and good reproducibility. The prepared sensor exhibits excellent performance in terms of sensitivity, selectivity, stability and practicality.

[0078] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A uric acid sensor based on NiCo-BTC composite material, characterized in that, The device includes a substrate, an electrode system fabricated on the substrate, a sensing element, and an insulating layer. The sensing element is electrically connected to the electrode system and is used to detect the concentration of uric acid molecules in a sample solution and generate a current signal. The electrode system is used for current conduction. The insulating layer is disposed in a non-working area of ​​the electrode system away from the sensing element and is used to protect the electrode system and isolate the sample solution from the electrode system at the end away from the sensing element. The sensing element is made of NiCo-BTC@CC composite material, which includes conductive carbon cloth and a NiCo-BTC layer grown in situ on the surface of its fibers.

2. The uric acid sensor based on NiCo-BTC composite material according to claim 1, characterized in that, The microstructure of the NiCo-BTC layer is an array of NiCo-BTC nanosheets.

3. A uric acid sensor based on NiCo-BTC composite material according to claim 2, characterized in that, The thickness of the NiCo-BTC nanosheets is 4-5 nm.

4. A uric acid sensor based on NiCo-BTC composite material according to any one of claims 1 to 3, characterized in that, The electrode system includes a working electrode, a counter electrode, and a reference electrode, and the sensing element is electrically connected to the working electrode.

5. A uric acid sensor based on NiCo-BTC composite material according to any one of claims 1 to 3, characterized in that, The substrate material includes polyethylene terephthalate, polyimide, or polyvinyl butyral.

6. A method for preparing a uric acid sensor based on NiCo-BTC composite material, characterized in that, The preparation of a uric acid sensor based on NiCo-BTC composite material as described in any one of claims 1 to 5 comprises the following steps: S1. Clean and acid-etch the conductive carbon cloth. S2. Using cobalt nitrate and nickel nitrate as metal sources and pyromellitic acid as an organic ligand, a NiCo-BTC layer is grown on the surface of the conductive carbon cloth to obtain the NiCo-BTC@CC composite material. S3. Sequentially fabricate the working electrode, counter electrode, and reference electrode on the top surface of the substrate; S4. Connect the NiCo-BTC@CC composite material to the working electrode using conductive silver paste, and then encapsulate it to obtain a uric acid sensor based on NiCo-BTC composite material.

7. The method for preparing a uric acid sensor based on NiCo-BTC composite material according to claim 6, characterized in that, In step S1, the acid etching process specifically involves placing the cleaned conductive carbon in a dilute hydrochloric acid solution with a concentration of 0.5-2 mol / L and etching it at 50-80°C for 20-40 minutes.

8. The method for preparing a uric acid sensor based on NiCo-BTC composite material according to claim 6, characterized in that, In step S2, the specific steps are as follows: S201. Preparation of precursor solution: Dissolve cobalt nitrate hexahydrate, nickel nitrate hexahydrate and trimesic acid in anhydrous ethanol to obtain a mixed solution; S202, Hydrothermal reaction: The conductive carbon cloth pretreated in step S1 is immersed in the precursor solution and placed in a hydrothermal reactor for reaction at 120-180°C for 10-18 hours. S203. Post-processing: After the reaction is complete, the carbon cloth loaded with the product is removed, and after cleaning and drying, the NiCo-BTC@CC composite material is obtained.

9. The method for preparing a uric acid sensor based on NiCo-BTC composite material according to claim 8, characterized in that, Co in the mixed solution 2+ with Ni 2+ The molar ratio is (0.5-2):1, and the molar ratio of total metal ion concentration to trimesic acid is 1:(0.8-1.2).

10. A method for preparing a uric acid sensor based on NiCo-BTC composite material according to any one of claims 6 to 9, characterized in that, In step S3, the electrode system is prepared by screen printing, inkjet printing or photolithography. The working electrode is a silver electrode, the counter electrode is a carbon electrode, and the reference electrode is an Ag / AgCl electrode.

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