Dual-mode flexible thermocouple sensor and preparation method thereof

Abstract

The invention discloses a dual-mode flexible thermocouple sensor and a preparation method thereof. The sensor comprises a P-type thermocouple, an N-type thermocouple and a flexible substrate, the flexible substrate comprises a first area located in the middle and a second area located on the periphery of the first area. The P-type thermocouple and the N-type thermocouple are arranged in the second area of the flexible substrate and connected with the absorber located in the first area. The sensitivity of the sensor in a contact mode is not lower than 350 [mu] V / DEG C, and the sensitivity of the sensor in a non-contact mode is not lower than 50 [mu] V / DEG C. The sensor provided by the invention can realize contact and non-contact dual-mode temperature monitoring, and has the advantages of high sensitivity, wide detection range, high resolution and short response time.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, and in particular to a dual-mode flexible thermocouple sensor and a preparation method thereof. Background Art

[0002] Temperature monitoring technology is crucial in modern industry, medical treatment, environmental monitoring and other fields. Although traditional rigid thermocouple sensors perform well in stability and measurement accuracy, they have significant limitations in flexible and embedded applications. Rigid sensors are difficult to adapt to complex surface shapes and dynamic environments, which not only reduces measurement accuracy but also may cause sensor damage, limiting their widespread use in flexible applications.

[0003] With the rapid development of flexible electronic technology, the market demand for flexible temperature sensors has increased significantly. Flexible thermocouple sensors (FTCS) can achieve real-time and accurate temperature measurement due to their light weight, portability and excellent shape adaptability. However, existing FTCS still face many challenges in terms of thermoelectric performance, sensitivity, detection range and response speed. At present, most research is still mainly focused on the contact temperature monitoring mode. Although this mode has high sensitivity in the measurement of the fitted surface, its application is limited in complex environments, especially difficult to meet the needs of non-contact temperature monitoring. In addition, whether in contact or non-contact mode, the insufficient performance of thermoelectric materials will directly affect the sensitivity and response speed of the sensor. Traditional flexible sensors are difficult to effectively convert infrared radiation energy into heat energy in non-contact temperature monitoring, and existing thermoelectric materials are usually difficult to achieve an optimal balance between the Seebeck coefficient, electrical conductivity and thermal conductivity, which further limits the application potential of FTCS in dual-mode (contact / non-contact) monitoring.

[0004] Thermoelectric materials are the core components of FTCS, and their performance is determined by the ZT value (thermoelectric figure of merit). The ZT value depends on the comprehensive performance of the Seebeck coefficient (S), electrical conductivity (σ), absolute temperature (T) and thermal conductivity (κ), among which the power factor (PF, PowerFactor), that is, is particularly important in optimizing thermoelectric performance. The PF value not only directly affects the energy conversion efficiency of thermoelectric materials, but is also a key indicator for measuring the comprehensive performance of thermoelectric materials. Traditional inorganic thermoelectric materials such as bismuth telluride (BiTe), lead telluride (PbTe) and bismuth selenide (BiSe) are highly favored due to their high PF values, but their inherent rigidity, high cost and poor compatibility with flexible substrates limit their application in flexible sensors. In contrast, polymer materials and inorganic nanomaterials have become research hotspots due to their advantages of flexibility, low toxicity and low cost, but their thermoelectric performance is usually one order of magnitude lower than that of traditional inorganic materials, making it difficult to meet the needs of high-performance FTCS.

[0005] In response to the above problems, researchers have tried to improve the performance of thermoelectric materials by combining different types of materials. For example, fillers with high Seebeck coefficients are introduced into P-type or N-type matrix materials to enhance their thermoelectric properties. However, the preparation process of these composite materials is often complicated and costly, and it is difficult to achieve large-scale deposition or printing on flexible substrates, which seriously limits their practical application in the field of flexible sensors. In addition, MXene and CNT, as commonly used N-type and P-type thermoelectric materials, although they have attracted attention due to their flexibility and conductivity, have low Seebeck coefficients and PF values, which make it difficult to meet the high requirements of sensitivity and response speed for dual-mode temperature monitoring. This further highlights the necessity of developing high-performance composite thermoelectric materials to meet the needs of flexible sensors. Summary of the invention

[0006] Based on the technical problems existing in the background technology, the present invention proposes a dual-mode flexible thermocouple sensor and a preparation method thereof, which can realize contact and non-contact dual-mode temperature monitoring and has high sensitivity, wide detection range, high resolution and fast response time.

[0007] A dual-mode flexible thermocouple sensor proposed in the present invention comprises a P-type thermocouple, an N-type thermocouple and a flexible substrate; The flexible substrate comprises a first region located in the middle and a second region located outside the first region, the P-type thermocouple and the N-type thermocouple are arranged in the second region of the flexible substrate and connected to the absorber located in the first region; The conductivity of the P-type thermocouple is not less than 60000S / m, the Seebeck coefficient is not less than 40 / K, and the power factor is not less than 95μW / mK; The conductivity of the N-type thermocouple is not less than 55000 S / m, the Seebeck coefficient is not less than -30 / K, and the power factor is not less than 55 μW / mK.

[0008] The sensitivity of the sensor in contact mode is not less than 350μV / ℃, and the sensitivity in non-contact mode is not less than 50μV / ℃.

[0009] Preferably, the P-type thermocouple is composed of PEDOT:PSS and CNTs in a mass ratio of 1.5-2.5:1.

[0010] Preferably, the N-type thermocouple is made of MXene and Bi 2 Se 3 The composition is in a mass ratio of 1.5-2.5:1.

[0011] Preferably, a support layer is further provided on one side of the flexible substrate.

[0012] Preferably, a cavity is provided on one side of the support layer located on the flexible substrate, and the cavity completely covers the absorber, the P-type thermocouple and the N-type thermocouple.

[0013] Preferably, the ends of the P-type thermocouple and the N-type thermocouple away from the absorber are connected through a carbon electrode.

[0014] The present invention provides a method for preparing a dual-mode flexible thermocouple sensor, and the method steps are as follows: S1: Printing PDMS / Si on the second area of ​​the flexible substrate 3 N 4 The mixture is heated and cured; S2: Print CNTs on the first area of ​​the flexible substrate and then print PDMS / Si after drying 3 N 4 The mixture is heated and cured; S3: printing a P-type thermocouple and an N-type thermocouple in the second area, and one end of the P-type thermocouple and the N-type thermocouple are connected to the first area; S4: Finally, PDMS / Si is printed on both the first area and the second area 3 N 4 mixture to form a protective layer.

[0015] Beneficial technical effects of the present invention: The design of P-type thermocouple and N-type thermocouple adopted by the sensor of the present invention significantly improves the comprehensive performance of a single material, such as conductivity, Seebeck coefficient and ZT value, meets the high performance requirements of contact and non-contact temperature monitoring, and the sensor has high temperature sensitivity and response speed in non-contact mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of the dual-mode flexible thermocouple sensor proposed in the present invention; Figure 2 A cross-sectional view of the dual-mode flexible thermocouple sensor proposed by the present invention; Figure 3 This is a working principle diagram of the dual-mode flexible thermocouple sensor proposed by the present invention; Figure 4 Actual image and SEM image of the dual-mode flexible thermocouple sensor proposed in the present invention.

[0017] In the figure: 1-flexible substrate, 2-P-type thermocouple, 3-N-type thermocouple, 4-support layer, 5-absorber, 6-carbon electrode, 7-cavity. DETAILED DESCRIPTION

[0018] The present invention will be further explained below in conjunction with specific embodiments.

[0019] Example 1 A dual-mode flexible thermocouple sensor proposed in the present invention comprises a P-type thermocouple 2, an N-type thermocouple 3 and a flexible substrate 1; The flexible substrate 1 includes a first area located in the middle and a second area located outside the first area, and a P-type thermocouple 2 and an N-type thermocouple 3 are arranged in the second area of ​​the flexible substrate and connected to an absorber 5 located in the first area; The conductivity of the P-type thermocouple is 61197.88S / m, the Seebeck coefficient is 39.88 / K, and the power factor is 97.66μW / mK; The conductivity of the N-type thermocouple is 55697.77S / m, the Seebeck coefficient is -29.45 / K, and the power factor is 55.64μW / mK.

[0020] The sensor has a sensitivity of 379.5 μV / °C in contact mode, a detection range of 20-200°C, a resolution of approximately 0.3°C, and a response time of approximately 12.6 ms.

[0021] The sensitivity of the sensor in non-contact mode is no less than 50μV / °C, the detection range is 20-200°C, the resolution is about 0.8°C, and the response time is about 9.8ms.

[0022] Specifically, the P-type thermocouple is composed of PEDOT:PSS and CNTs in a mass ratio of 2:1; the N-type thermocouple is composed of MXene and Bi 2 Se 3 It is composed in a mass ratio of 2:1.

[0023] In addition, a support layer 4 is provided on one side of the flexible substrate 1; a cavity 7 is provided on one side of the support layer 4 located on the flexible substrate 1, and the cavity 7 completely covers the absorber 5, the P-type thermocouple 2 and the N-type thermocouple 3; the cavity structure can reduce heat flux loss and enhance the thermoelectric effect to form a flexible three-dimensional structure.

[0024] The ends of the P-type thermocouple 2 and the N-type thermocouple 3 away from the absorber are connected through the carbon electrode 6; in order to improve the integration of the support layer and facilitate heat dissipation, thermal conductive silica gel is applied at the connection point.

[0025] Depend on Figure 4 It can be seen that the contact angle of the entire sensor is 102.9°, showing strong hydrophobicity.

[0026] The sensor of the present invention exhibits excellent mechanical durability and can maintain stable performance even after 1000 bending cycles.

[0027] The present invention provides a method for preparing a dual-mode flexible thermocouple sensor, and the method steps are as follows: S1: PPSN (paper / PDMS / ) was selected as the flexible substrate. PDMS (polydimethylsiloxane) provided good mechanical stability and chemical inertness. 3 N 4 The (silicon nitride) nanoparticles enhance the thermal stability and mechanical strength of the substrate, and the selected filter paper is first dried in a vacuum drying oven to ensure good adhesion between PDMS and paper and prevent moisture from affecting the performance of the flexible substrate.

[0028] In addition, Si 3 N 4 Surface modification of nanoparticles, i.e. Si 3 N 4 The nanoparticles were chemically modified with a silane coupling agent (SCA) to form chemical bonds with the PDMS, ensuring a strong connection between the PPSN base materials.

[0029] Use AutoCAD software to design the sensor pattern and make the corresponding silk screen for subsequent screen printing.

[0030] S2: Printing PDMS / Si on the second area of ​​the flexible substrate 3 N 4 The mixture is heated and cured; CNTs are printed on the circular first area of ​​the flexible substrate, and then PDMS / Si is printed after drying. 3 N 4 The mixture is heated and cured; S3: Printing a P-type thermocouple and an N-type thermocouple in the second area, connecting one end of the P-type thermocouple and the N-type thermocouple to the first area, ensuring that they are evenly distributed around the first area; connecting the P-type thermocouple and the N-type thermocouple using carbon electrodes to facilitate transmission of electrical signals; S4: Finally, PDMS / Si is printed on both the first area and the second area 3 N 4 mixture to form a protective layer to protect thermocouple materials from oxidation and contamination.

[0031] Example 2 The P-type thermocouple of this embodiment is composed of PEDOT:PSS and CNTs in a mass ratio of 1.5:1; the N-type thermocouple is composed of MXene and Bi 2 Se 3 The composition is in a mass ratio of 1.5:1.

[0032] The remaining conditions are the same as those in Example 1.

[0033] Example 3 The P-type thermocouple of this embodiment is composed of PEDOT:PSS and CNTs in a mass ratio of 2.5:1; the N-type thermocouple is composed of MXene and Bi 2 Se 3 The composition is in a mass ratio of 2.5:1.

[0034] The remaining conditions are the same as those in Example 1.

[0035] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application. The scope of the present application is defined by the appended claims and their equivalents, and all shall be included in the scope of protection of the present application.

Claims

1. A dual-mode flexible thermocouple sensor, characterized in that: It comprises a P-type thermocouple (2), an N-type thermocouple (3) and a flexible substrate (1); The flexible substrate (1) comprises a first region located in the middle and a second region located outside the first region, the P-type thermocouple (2) and the N-type thermocouple (3) are arranged in the second region of the flexible substrate and connected to the absorber (5) located in the first region; The conductivity of the P-type thermocouple is not less than 60000S / m, the Seebeck coefficient is not less than 40 / K, and the power factor is not less than 95μW / mK; The conductivity of the N-type thermocouple is not less than 55000 S / m, the Seebeck coefficient is not less than -30 / K, and the power factor is not less than 55 μW / mK.

2. The sensitivity of the sensor in contact mode is not less than 350μV / ℃, and the sensitivity in non-contact mode is not less than 50μV / ℃.

3. A dual-mode flexible thermocouple sensor according to claim 1, characterized in that: The P-type thermocouple is composed of PEDOT:PSS and CNTs in a mass ratio of 1.5-2.5:

1.

4. A dual-mode flexible thermocouple sensor according to claim 1, characterized in that: The N-type thermocouple is composed of MXene and Bi2Se3 in a mass ratio of 1.5-2.5:

1.

5. A dual-mode flexible thermocouple sensor according to claim 1, characterized in that: A supporting layer (4) is also provided on one side of the flexible substrate (1).

6. A dual-mode flexible thermocouple sensor according to claim 4, characterized in that: The support layer (4) is provided with a cavity (7) on one side of the flexible substrate (1), and the cavity (7) completely covers the absorber (5), the P-type thermocouple (2), and the N-type thermocouple (3).

7. A dual-mode flexible thermocouple sensor according to claim 1, characterized in that: The ends of the P-type thermocouple (2) and the N-type thermocouple (3) away from the absorber are connected via a carbon electrode (6).

8. A method for preparing a dual-mode flexible thermocouple sensor according to any one of claims 1 to 6, characterized in that: The steps are as follows: S1: Printing a PDMS / Si3N4 mixture on the second area of ​​the flexible substrate and heating and curing; S2: Printing CNTs on the first area of ​​the flexible substrate, and then printing the PDMS / Si3N4 mixture after drying and heating to cure; S3: printing a P-type thermocouple and an N-type thermocouple in the second area, and one end of the P-type thermocouple and the N-type thermocouple are connected to the first area; S4: Finally, the PDMS / Si3N4 mixture is printed on both the first area and the second area to form a protective layer.

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