In-situ electrode plasma discharge modified flexible film thermocouple and preparation method thereof

Abstract

The invention belongs to the technical field of sensors, and discloses an in-situ electrode plasma discharge modified flexible film thermocouple and a preparation method thereof, and the method comprises the steps: preparing positive electrode, negative electrode and insulating layer slurry; forming a positive electrode film, an insulating layer and a negative electrode film on the flexible insulating substrate through silk-screen printing, and curing; sintering the thermocouple matrix; the positive electrode and the negative electrode of the thermocouple are used as ground electrodes for plasma discharge, plasma discharge treatment is carried out in a nitrogen environment, and nitrogen element doping is achieved. The graphene is added in the electrode of the thermocouple, and the in-situ electrode plasma discharge technology is adopted, so that the conductivity and the stability of the thermocouple are improved, and the thermocouple is suitable for high-precision temperature measurement of irregular curved surfaces, and has the advantages of simple process and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of sensors, and in particular relates to an in-situ electrode plasma discharge modified flexible thin film thermocouple and a preparation method thereof. Background Art

[0002] In modern industrial temperature measurement, thermocouples, thanks to their superior performance characteristics, have become the dominant technology for measuring wall temperatures. These sensors utilize direct contact measurement, eliminating the need for any intermediate medium, ensuring highly accurate measurements. Thin-film thermocouples combine a wide temperature measurement range, long service life, compact size, lightweight, and easy installation. These attributes make them indispensable for monitoring transient temperatures in critical aircraft engine components, such as turbine blades, combustion chamber walls, and high-temperature gas paths, in extreme environments. Their superior performance enables them to continuously provide accurate and reliable temperature data under these demanding conditions.

[0003] However, due to the use of hard substrate materials, it is difficult to achieve flexible measurement on irregular surfaces. Since the spacing between the measuring elements in the thermocouple sensor array is large, the spatial resolution of the system is limited, thereby affecting the measurement accuracy. If the spatial resolution of the measurement area is to be improved, the density of the sensor elements needs to be increased. However, increasing the number of sensors will bring practical problems such as increased wiring complexity and rising costs. In the existing method of making temperature sensors, such as patent CN109338290B, the thermocouple prepared is a single-junction thermocouple, which cannot measure the temperature field.

[0004] At the same time, existing semiconductor thermocouples have a high resistance, making it difficult to discharge the thermocouple as a ground electrode. Using other plasma discharge devices, such as plasma jets or dielectric barrier discharges, effectively doping with nitrogen is impossible. Plasma jets cannot nitrogen-dope the entire thermoelectric material, and using dielectric barrier discharges causes many of the short-lived nitrogen-containing particles generated by the plasma to quench before reaching the material surface, reducing the nitrogen doping effect.

[0005] Therefore, the market urgently needs a simple-to-operate and efficient plasma discharge nitrogen-doped modified flexible thermocouple and preparation solution. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides an in-situ electrode plasma discharge modified flexible thin film thermocouple and a preparation method thereof.

[0007] A method for preparing an in-situ electrode plasma discharge modified flexible thin film thermocouple comprises the following steps: Slurry preparation: preparation of positive electrode slurry, negative electrode slurry and insulating layer slurry; Substrate preparation: The positive electrode pattern, insulating layer pattern, and negative electrode pattern are respectively printed on a flexible insulating substrate by screen printing and cured to form a positive electrode film, an insulating layer, and a negative electrode film, wherein one end of the positive electrode film overlaps with one end of the negative electrode film to form a thermal junction; Matrix curing: sintering the matrix; Nitriding treatment: The positive and negative electrodes of the thermocouple are used as electrodes for plasma discharge, and plasma discharge treatment is performed in a nitrogen environment to achieve nitrogen doping.

[0008] Furthermore, the positive electrode slurry is prepared by mixing terpineol solvent, epoxy resin, polyetheramine and positive electrode active material; The negative electrode slurry is prepared by mixing terpineol solvent, epoxy resin, polyetheramine and negative electrode active material; The insulating layer slurry is prepared by mixing epoxy resin, 1-methyl-2-pyrrolidone, polyethylene glycol and insulating material.

[0009] Furthermore, the positive electrode active material is selected from indium tin oxide, , PtPh, NiCr; The negative electrode active material is selected from one of indium oxide, indium tin oxide, Pt, and NiSi, and is different from the positive electrode active material; The insulation material is polyimide or fluorphlogopite.

[0010] Furthermore, the positive electrode slurry and the negative electrode slurry also contain graphene; The positive electrode active material, negative electrode active material, insulating material and graphene are all in powder form with a particle size of 30-50 nm; The flexible insulating substrate is selected from a polyimide substrate or a fluorophlogopite substrate.

[0011] Furthermore, the printing width of the positive electrode film and the negative electrode film is 0.5-1 mm, and the overlapping length of the thermal junction is 1 cm.

[0012] Furthermore, the printed positive electrode pattern, insulating layer pattern, and negative electrode pattern were dried at 150° C. for 20 minutes for preliminary curing; During the solidification of the matrix, the sintering temperature is 200-300° C. and the sintering time is 2-5 hours.

[0013] Furthermore, during the nitriding treatment, the positive and negative electrodes of the thermocouple are connected to the low-voltage electrode of the pulse power supply through a low-voltage electrode wire, a copper foil is covered on the back of the flexible insulating substrate as a high-voltage electrode, and the substrate is placed in a shielding cover in a nitrogen environment for plasma discharge.

[0014] Furthermore, in the nitriding treatment, the parameters of plasma discharge are: nitrogen flow rate 30 SCCM, pulse rising edge 50 ns, pulse amplitude 4.5 kV, pulse frequency 1 kHz, pulse width 100 μs, and treatment time 10-15 minutes.

[0015] The in-situ electrode plasma discharge modified flexible thin film thermocouple prepared by the above-mentioned preparation method of the in-situ electrode plasma discharge modified flexible thin film thermocouple comprises a flexible substrate, a positive electrode thin film, a negative electrode thin film and an insulating layer; The positive electrode film is arranged on a flexible insulating substrate; The insulating layer is arranged on the positive electrode film at the intersection of the positive and negative electrodes of the modified flexible film thermocouple; The negative electrode film is arranged on the insulating substrate and the insulating layer; One end of the positive electrode film overlaps with one end of the negative electrode film to form a hot junction, and the other ends of the positive electrode film and the negative electrode film serve as cold ends; The positive electrode film and the negative electrode film are subjected to plasma discharge nitriding treatment.

[0016] Furthermore, the positive electrode film and the negative electrode film contain graphene; The nitrogen content in the positive electrode film and the negative electrode film is 3-4% through plasma discharge nitriding treatment.

[0017] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: 1. The present invention adopts the self-electrode surface discharge design, directly uses the thermoelectric material as the discharge electrode, and constructs a coaxial surface discharge structure to ensure that all plasma active nitrogen species (including metastable ) acts on the material surface at zero distance; highly active nitrogen particles (such as N•, etc.) can be directly and efficiently injected into the crystal lattice of thermoelectric materials to achieve deeply controllable nitrogen gradient doping; significantly reducing the transmission loss of active particles in traditional plasma doping technology, and realizing the integrated integration of doping process and device function, laying a solid foundation for the subsequent performance optimization of thermoelectric devices.

[0018] 2. Modification of the graphene conductive network: by in-situ compounding of a three-dimensional graphene network, the resistivity of the material is significantly reduced; the electrode voltage drop is small during discharge, and the Joule heating effect is suppressed to keep the process temperature rise less than 15°C; 3. The positive and negative electrodes prepared by this method have high electrical and thermal conductivity. High electrical conductivity can significantly improve the electrical conductivity of the thermocouple, thereby enhancing the output signal, and help to increase the Seebeck coefficient, further optimizing the thermoelectric effect. At the same time, high thermal conductivity enables the thermocouple to respond quickly to temperature changes, effectively improving measurement accuracy.

[0019] 4. The invented flexible temperature sensor uses a screen printing process to prepare a thermocouple structure on a flexible insulating substrate. This method has the characteristics of simple process and low equipment requirements, and can realize the in-situ preparation and measurement of the sensor, providing a feasible technical solution for the in-situ preparation and large-scale production of flexible temperature sensors.

[0020] 5. The sensor's array sensitive area is composed of multiple positive and negative thermocouples, which overlap to form thermocouple nodes. Through precise design, all thermocouple nodes are located within the temperature measurement area. This innovative structural design successfully solves two key technical challenges of traditional thermocouple sensors within the temperature measurement area: the proper placement of sensor measurement locations and the difficulty of lead wiring, thereby improving the accuracy and reliability of temperature measurement.

[0021] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 Schematic diagram of the structure of the flexible thin film thermocouple of the present invention; Figure 2 The wiring diagram of the flexible thin film thermocouple of the present invention undergoing plasma discharge modification; Figure 3 Schematic diagram of the in-situ electrode plasma discharge nitrogen doping device of the present invention; Figure 4 This is a diagram showing the calibration results of indium oxide and indium tin oxide thermocouples in one embodiment of the present invention; Figure 5 Added graphene thermocouple calibration result diagram for one embodiment of the present invention; Figure 6 This is a graph showing the calibration results of a thermocouple with graphene added and plasma discharge nitrogen doping in one embodiment of the present invention; Figure 7 The energy spectrum and SEM image of the In2O3 electrode prepared in one embodiment of the present invention; Figure 8 The energy spectrum and SEM image of the ITO electrode prepared in one embodiment of the present invention; Figure 9The energy spectrum and SEM image of the graphene-added In2O3 electrode prepared in one embodiment of the present invention; Figure 10 The energy spectrum and SEM image of the graphene-added ITO electrode prepared in one embodiment of the present invention; Figure 11 The energy spectrum and SEM image of the In2O3 electrode nitrided with graphene added prepared in one embodiment of the present invention; Figure 12 The energy spectrum and SEM image of the nitrided ITO electrode after adding graphene prepared in one embodiment of the present invention.

[0024] Wherein: 1. Flexible insulating substrate; 2. Positive electrode film; 3. Insulation layer; 4. Negative electrode film; 5. Hot junction; 6. Cold junction; 11. Flexible thin film thermocouple; 12. Copper foil; 13. Low-voltage electrode wire; 14. High-voltage electrode wire; 15. Pulsed high-voltage power supply; 16. Flow controller; 17. Shielding cover; 18. Gas source. DETAILED DESCRIPTION

[0025] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0026] To address the limitations of traditional thermocouples in achieving high spatial resolution temperature measurement and their difficulty in properly adhering to the surface of the object being measured, an arrayed measurement approach achieves higher measurement accuracy and spatial resolution, solving the problem of routing a large number of signal lines. This sensor structure and fabrication process are simple and cost-effective, improving the temperature measurement efficiency of thin-film thermocouples.

[0027] Using the thermoelectric material itself as the electrode for surface discharge can effectively dope the nitrogen-containing particles generated by the discharge into the thermocouple, and dope them evenly. On the other hand, the incorporation of graphene can effectively reduce the resistance of the thermocouple, which can reduce the current and voltage drop on the thermoelectric material during discharge and reduce heat generation.

[0028] This application proposes a surface discharge doping technology based on graphene composite modification, which achieves efficient and uniform nitrogen doping through dual optimization: on the one hand, the thermoelectric material itself is used as the surface discharge ground electrode to construct a dielectric barrier discharge structure, so that all active nitrogen particles generated in the plasma region directly act on the surface of the thermoelectric material, achieving gradient doping throughout the depth of the material; on the other hand, a three-dimensional conductive network of graphene is introduced to reduce the resistivity of the thermoelectric material by 2-3 orders of magnitude, effectively suppressing the Joule heating effect during the discharge process.

[0029] like Figure 1 As shown, the main components of the flexible thin film thermocouple are shown.

[0030] The flexible thin film thermocouple 11 includes a flexible insulating substrate 1 and a positive electrode film 2, an insulating layer 3 and a negative electrode film 4 arranged on the flexible insulating substrate 1, wherein one end of the positive electrode film 2 overlaps with one end of the negative electrode film 4 to form a hot junction 5, and the other end of the positive electrode thermocouple film and the other end of the negative electrode thermocouple film serve as a cold end 6.

[0031] The method for preparing flexible thin film thermocouples is described below.

[0032] A method for preparing an in-situ electrode plasma discharge modified flexible thin film thermocouple comprises the following steps: S1 slurry preparation, Prepare positive electrode slurry, negative electrode slurry and insulating layer slurry according to the slurry ratio. S2 matrix preparation, The positive electrode pattern was printed on the flexible substrate using the positive electrode slurry using a positive electrode screen printing mask, and then placed in a drying oven at 150°C for 20 minutes to cure to form a positive electrode film; Use an insulating layer slurry and an insulating layer screen printing mask to print the insulating layer pattern at the intersection of the positive and negative poles of the pre-designed thermocouple. Then place it in a 150°C drying oven for 20 minutes to cure to form an insulating layer to ensure that the positive and negative poles are not conductive. The negative electrode slurry was used to print the positive electrode pattern on the flexible substrate using a negative electrode screen printing mask, and then placed in a drying oven at 150°C for 20 minutes to cure to form a negative electrode film; A thermocouple substrate is prepared.

[0033] S3 matrix curing The thermocouple substrate is placed in an atmospheric environment at a temperature of 200° C. to 300° C. and sintered for 1 to 5 hours to prepare a flexible thin film thermocouple.

[0034] S4 nitriding treatment The positive and negative electrodes of the flexible thin film thermocouple are used as electrodes for plasma discharge and plasma discharge is performed under nitrogen conditions to obtain a nitrided flexible thin film thermocouple.

[0035] In S2, the printing width of the positive and negative electrode substrates is controlled at 0.5-1 mm; Among them, one end of the positive electrode film overlaps with one end of the negative electrode film to form a thermal junction, which serves as a temperature sensitive area, and the overlapping length is 1 cm.

[0036] The positive electrode slurry is prepared by mixing terpineol solvent, epoxy resin, polyetheramine and positive electrode active material; The negative electrode slurry is prepared by mixing terpineol solvent, epoxy resin, polyetheramine and negative electrode active material; The insulating layer slurry is prepared by mixing epoxy resin, 1-methyl-2-pyrrolidone (NMP), polyethylene glycol and insulating material.

[0037] The positive electrode active material is indium tin oxide, La 0.67 Sr 0.33 One of MnO3 (LSMO), PtPh, NiCr, The negative electrode active material is one of indium oxide, indium tin oxide, Pt, and NiSi, and is limited to being different from the material of the thermocouple positive electrode active material.

[0038] In a further improvement, in order to improve the conductivity of the positive and negative electrodes of the thermocouple and reduce the voltage drop, graphene is added to the positive and negative electrode slurries of the thermocouple.

[0039] The insulation material is polyimide or fluorphlogopite.

[0040] The positive electrode active material, negative electrode active material, graphene and insulating material are all in powder form, and the diameter is controlled at 30-50nm.

[0041] The prepared flexible thin film thermocouple includes a flexible insulating substrate and a positive electrode film, an insulating layer and a negative electrode film printed on the flexible insulating substrate. The insulating layer is located at the intersection of the positive electrode film and the negative electrode film to prevent the positive electrode film and the negative electrode film from being conductive.

[0042] The overlapping part of one end of the positive electrode film and one end of the negative electrode film forms a hot junction, and the free ends of the positive electrode film and the negative electrode film are cold ends.

[0043] It should be noted that the flexible insulating substrate can be a polyimide substrate or a fluorophlogopite substrate. The polyimide substrate will produce carbonization at high temperatures and is suitable for use when the test temperature is lower than 400°C. The fluorophlogopite substrate is suitable for use when the test temperature is lower than 1100°C.

[0044] For thermal flow measurements above 400°C, a fluorphlogopite substrate combined with a thin-film thermocouple is essential. For thermal flow measurements below 400°C, however, the choice of substrate material and thin-film thermocouple is more flexible, allowing for different material combinations to be used based on actual requirements. This principle of material selection based on the measurement temperature range ensures reliable sensor operation under diverse operating conditions.

[0045] Example 1 Execute preparation process S1-S3; S1 slurry preparation, The positive electrode slurry is prepared by mixing pineol solvent, epoxy resin, polyetheramine and indium tin oxide powder; The negative electrode slurry is prepared by mixing terpineol solvent, epoxy resin, polyetheramine and indium oxide powder; The insulating layer slurry is prepared by mixing epoxy resin, 1-methyl-2-pyrrolidone (NMP), polyethylene glycol and polyimide powder.

[0046] Among them, indium tin oxide powder accounts for 79.2g, terpineol accounts for 8.5g, polyetheramine accounts for 4.4g, and epoxy resin accounts for 7.9g in the positive electrode printing paste. In the negative electrode printing paste, indium oxide powder accounts for 79.2g, terpineol accounts for 8.5g, polyetheramine accounts for 4.4g, and epoxy resin accounts for 7.9g. The insulating layer slurry contains 70g of polyimide powder, 5g of polyethylene glycol, 10g of 1-methyl-2-pyrrolidone, and 15g of epoxy resin; S2 matrix preparation, The printing width of the positive electrode substrate and the negative electrode substrate is 0.5 mm.

[0047] During the curing of the S3 matrix, sintering was performed at 200°C in an atmospheric environment for 4.5 hours.

[0048] Example 2 S1 slurry preparation, The positive electrode printing paste of Example 1 was prepared by adding 1.98 g of indium tin oxide powder and graphene powder and mixing them evenly to obtain the positive electrode paste of this example. The negative electrode printing paste of Example 1 was prepared by adding 1.98 g of indium oxide powder and graphene powder and mixing them evenly to obtain the negative electrode paste of this example. The insulating layer slurry is the same as that in Example 1.

[0049] S2 matrix preparation, The printing width of the positive electrode substrate and the negative electrode substrate is 1 mm.

[0050] During the curing of the S3 matrix, sintering was performed at 300°C in an atmospheric environment for 2 hours.

[0051] Example 3 S1 slurry preparation, The prepared slurry was consistent with the various slurries of Example 2.

[0052] S2 substrate printing, The printing width of the positive electrode substrate and the negative electrode substrate is 0.8 mm.

[0053] During the curing of the S3 matrix, sintering was performed at 250°C in an atmospheric environment for 3.5 hours.

[0054] The thermocouple prepared in S4 was nitrided.

[0055] like Figure 3 As shown, the structure and main components of the plasma generating device are shown, and the method of performing plasma discharge nitriding treatment on the flexible thin film thermocouple is also shown.

[0056] like Figure 2 FIG. 1 shows a wiring method for a flexible thin film thermocouple for plasma discharge treatment.

[0057] The cold end 6 of the flexible thin film thermocouple 11 is connected to the low voltage electrode of the pulse power supply through the low voltage electrode wire 13 as the low voltage electrode for plasma discharge; The copper foil 12 is covered in the area where the positive thermocouple film and the negative thermocouple film of the flexible insulating substrate 1 of the flexible film thermocouple 11 are located as the high-voltage electrode for plasma discharge, and is connected to the high-voltage electrode of the pulse power supply through the high-voltage electrode wire 14.

[0058] The connected flexible thin film thermocouple 11 is placed in the shielding cover 17, and the gas source 18 is turned on. The gas source 18 stores nitrogen. The flow rate of nitrogen entering the shielding cover 17 is controlled by the flow controller 16. Nitrogen is introduced into the shielding cover 17 for displacement to maintain a nitrogen environment in the shielding cover 17. The pulse high-voltage power supply 15 starts discharging and performs plasma discharge treatment on the flexible thin film thermocouple 11.

[0059] The parameters of the pulse high-voltage power supply are: nitrogen flow rate of 30 SCCM, pulse rising edge of the power drive unit of 50 ns, pulse amplitude of 4.5 kV, pulse frequency of 1 kHz, pulse width of 100 μs; processing time is 10-15 min.

[0060] An in-situ electrode plasma discharge modified flexible thin film thermocouple of nitrided graphene was prepared.

[0061] The specific process of calibrating the in-situ electrode plasma discharge modified flexible thin film thermocouple prepared in Examples 1-3 is as follows: The hot junction of a flexible thin-film thermocouple is placed in a muffle furnace, while the cold junction is located on a water-cooled platform outside the furnace. The hot junction is heated by the muffle furnace, while two K-type standard thermocouples monitor the temperatures of the hot junction and cold junction, respectively. This creates a temperature gradient between the cold and hot junctions, generating a thermoelectric potential based on the Seebeck effect. A data logger records the cold junction temperature, the hot junction temperature, and the voltage difference between the cold junctions of the two materials. The temperature sensor is calibrated based on the voltage and temperature difference data.

[0062] The results of calibrating the thermocouple using a calibration furnace are as follows: Figure 4-Figure 6 As shown in Figure 3, the effect of plasma modification on the thermocouple is verified.

[0063] Figure 4 The calibration results of the thermocouple prepared in Example 1 are as follows: Figure 5 The calibration results of the thermocouple prepared in Example 2 are: Figure 6 This is the calibration result of the thermocouple prepared in Example 3.

[0064] Linear fitting of the calibration curve yields the relationship between the output thermoelectric potential E and the temperature difference ΔT: E=a(ΔT)+b. Table 1 shows that doping a small amount of graphene into thermoelectric materials can improve electrical conductivity, contributing to improved overall material conductivity and the output potential and Seebeck coefficient of the thermocouple. The calibration curve of the flexible thin-film thermocouple treated with graphene doping and nitriding exhibits higher linearity, providing better measurement consistency and trend foresight.

[0065] from Figure 7-12 From the characterization results in Table 2, it can be seen that after the thermocouple is discharged as an electrode of the plasma generator, its nitrogen content is improved to a certain extent, and the stability of the thermocouple temperature measurement is also improved. The reason for this is that nitrogen occupies the oxygen vacancies of indium oxide and indium tin oxide.

[0066] In summary, graphene doping within thermoelectric materials improves conductivity and output potential, enabling the thermocouple itself to function as a low-voltage electrode in a plasma generator. Further plasma discharge treatment, coupled with nitrogen doping, imparts excellent linear response and stability. Compared to conventional rigid-substrate temperature sensors, the sensor of this invention exhibits superior flexible deformation capabilities, allowing it to bend freely with the flexible film and conform perfectly to the surface of the object being measured, enabling precise in-situ temperature measurement of various curved surfaces.

[0067] Table 1 Fitting results of thermocouple calibration curve

[0068] Table 2 Element content in thermocouple (%)

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing an in-situ electrode plasma discharge modified flexible thin film thermocouple, characterized in that: The following steps are involved: Slurry preparation: preparation of positive electrode slurry, negative electrode slurry and insulating layer slurry; Substrate preparation: The positive electrode pattern, insulating layer pattern, and negative electrode pattern are respectively printed on a flexible insulating substrate by screen printing and cured to form a positive electrode film, an insulating layer, and a negative electrode film, wherein one end of the positive electrode film overlaps with one end of the negative electrode film to form a thermal junction; Matrix curing: sintering the matrix; Nitriding treatment: The positive and negative electrodes of the thermocouple are used as electrodes for plasma discharge, and plasma discharge treatment is performed in a nitrogen environment to achieve nitrogen doping.

2. The method for preparing the in-situ electrode plasma discharge modified flexible thin film thermocouple according to claim 1, characterized in that: The positive electrode slurry is prepared by mixing terpineol solvent, epoxy resin, polyetheramine and positive electrode active material; The negative electrode slurry is prepared by mixing terpineol solvent, epoxy resin, polyetheramine and negative electrode active material; The insulating layer slurry is prepared by mixing epoxy resin, 1-methyl-2-pyrrolidone, polyethylene glycol and insulating material.

3. The method for preparing the in-situ electrode plasma discharge modified flexible thin film thermocouple according to claim 2, characterized in that: The positive electrode active material is selected from indium tin oxide, , PtPh, NiCr; The negative electrode active material is selected from one of indium oxide, indium tin oxide, Pt, and NiSi, and is different from the positive electrode active material; The insulation material is polyimide or fluorphlogopite.

4. The method for preparing the in-situ electrode plasma discharge modified flexible thin film thermocouple according to claim 3, characterized in that: The positive electrode slurry and the negative electrode slurry also contain graphene; The positive electrode active material, negative electrode active material, insulating material and graphene are all in powder form with a particle size of 30-50 nm; The flexible insulating substrate is selected from a polyimide substrate or a fluorophlogopite substrate.

5. The method for preparing the in-situ electrode plasma discharge modified flexible thin film thermocouple according to claim 1, characterized in that: The printing width of the positive electrode film and the negative electrode film is 0.5-1 mm, and the overlapping length of the thermal junction is 1 cm.

6. The method for preparing the in-situ electrode plasma discharge modified flexible thin film thermocouple according to claim 1, characterized in that: The printed positive electrode pattern, insulating layer pattern, and negative electrode pattern were dried at 150°C for 20 minutes for preliminary curing; During the solidification of the matrix, the sintering temperature is 200-300° C. and the sintering time is 2-5 hours.

7. The method for preparing the in-situ electrode plasma discharge modified flexible thin film thermocouple according to claim 1, characterized in that: During the nitriding treatment, the positive and negative electrodes of the thermocouple are connected to the low-voltage electrode of the pulse power supply through low-voltage electrode wires, copper foil is covered on the back of the flexible insulating substrate as a high-voltage electrode, and the substrate is placed in a shielding cover in a nitrogen environment for plasma discharge.

8. The method for preparing the in-situ electrode plasma discharge modified flexible thin film thermocouple according to claim 1, characterized in that: During the nitriding treatment, the plasma discharge parameters are: nitrogen flow rate 30 SCCM, pulse rise time 50 ns, pulse amplitude 4.5 kV, pulse frequency 1 kHz, pulse width 100 μs, and treatment time 10-15 minutes.

9. An in-situ electrode plasma discharge modified flexible thin film thermocouple prepared by the preparation method of in-situ electrode plasma discharge modified flexible thin film thermocouple according to any one of claims 1 to 8, characterized in that: Including a flexible substrate, a positive electrode film, a negative electrode film and an insulating layer; The positive electrode film is arranged on a flexible insulating substrate; The insulating layer is arranged on the positive electrode film at the intersection of the positive and negative electrodes of the modified flexible film thermocouple; The negative electrode film is arranged on the insulating substrate and the insulating layer; One end of the positive electrode film overlaps with one end of the negative electrode film to form a hot junction, and the other ends of the positive electrode film and the negative electrode film serve as cold ends; The positive electrode film and the negative electrode film are subjected to plasma discharge nitriding treatment.

10. The in-situ electrode plasma discharge modified flexible thin film thermocouple according to claim 9, characterized in that: The positive electrode film and the negative electrode film contain graphene; The nitrogen content in the positive electrode film and the negative electrode film is 3-4% through plasma discharge nitriding treatment.

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