Strain-insensitive yarn strain sensor, its preparation method and application

Abstract

The present invention relates to the technical field of strain sensors, and particularly relates to a strain-insensitive yarn strain sensor, a preparation method thereof, and an application thereof. The preparation method is to in-situ grow a polyaniline nanoarray on the surface of an elastic core-spun yarn to obtain a polyaniline nanoarray-modified core-spun yarn, and then deposit MXene nanosheets to obtain an MXene / polyaniline nanoarray-modified core-spun yarn. Then, the MXene / polyaniline nanoarray-modified core-spun yarn is used as the core yarn and the skin yarn, and is synchronously wrapped to prepare a double-wrapped structure strain-insensitive yarn sensor. The preparation method of the present invention has the advantages of short process flow, simple method, low cost, strong popularization, small environmental pollution, large elastic elongation, insensitive strain resistance, and stable performance.

Description

Technical Field

[0001] The present invention relates to the technical field of strain sensors, and in particular to a strain-insensitive yarn strain sensor, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, the rapid development of flexible intelligent wearable electronic devices has put forward higher requirements for textiles, such as wireless information communication, intelligent perception and sensing, energy harvesting and storage, etc. An electronic circuit is an essential electronic component for transmitting electrical signals, and for wearable devices, electronic circuits usually receive less attention. Due to the fabric deformation and various curved surface deformations caused by the human body during movement, it will inevitably cause changes in the resistance and conductivity of the yarn, thereby affecting the performance degradation of the wearable device. Therefore, stable resistance and conductivity are crucial for wearable and stretchable electronic devices to ensure the stable performance of wearable devices. Traditional metal-based electronic circuits have attracted much attention due to their stable conductivity, but when applied to wearable electronic devices, there are problems such as signal drift due to human movement, poor comfort during wearing, poor washability, and poor human conformability. Compared with metal conductors, fiber / yarn-based conductors have better flexibility, but most of the reported stretchable conductive fiber strain sensors currently have deteriorated conductive performance when stretched. Therefore, stretchable electronic circuits with high stretchability and strain-insensitive characteristics are ideal choices for wearable devices and smart clothing.

[0003] To fabricate a strain-insensitive strain sensor, it is usually prepared based on two-dimensional materials by the following methods. For example, gold nanoparticle-modified electrospun elastic nanofiber mats (Park M, Im J, Shin M, et al. Highly stretchable electric circuits from a composite material of silver nanoparticles and elastomeric fibres[J]. Nature nanotechnology, 2012, 7(12):803-809.), SBS / microfibril network structures (Moon S, Park H K, Song J H, et al. Metal Deposition on a Self-Generated Microfibril Network to Fabricate Stretchable Tactile Sensors Providing Analog Position Information[J]. Advanced Materials, 2018, 30(32):1801408.), spring coil structures (Liu Z F, Fang S, Moura F A, et al. Hierarchically buckled sheath-core fibers for superelastic electronics, sensors, and muscles[J]. Science, 2015, 349(6246):400-404.), crack structures (Patent: ZL 201610329953.1, Zhou C G, Sun W J, Jia L C, et al. Highly stretchable and sensitive strain sensor with porous segregated conductive network[J]. ACS applied materials & interfaces, 2019, 11(40):37094-37102.). However, the resistance of the above two-dimensional stretchable electronic devices still changes significantly with strain, the elastic elongation of the fabricated devices is small, the stretchable strain range is small, and the material preparation process is relatively complex. Therefore, there is an urgent need to develop a one-dimensional, low-cost strain-insensitive strain sensor. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a strain-insensitive yarn strain sensor, a preparation method thereof and an application thereof, so as to solve the problems of complex existing preparation process flow and large change of yarn resistance with strain.

[0005] Based on the above purpose, the present invention provides a preparation method of a strain-insensitive yarn strain sensor. The preparation method is to in-situ grow a polyaniline nanoarray on the surface of an elastic core-spun yarn to obtain a polyaniline nanoarray modified core-spun yarn, and then deposit MXene nanosheets to obtain a MXene / polyaniline nanoarray modified core-spun yarn. Then, the MXene / polyaniline nanoarray modified core-spun yarn is used as the core yarn and the skin yarn, and is synchronously wrapped to prepare a double-wrapped structure strain-insensitive yarn sensor.

[0006] Preferably, the preparation method of the polyaniline nanoarray modified core-spun yarn includes the following steps:

[0007] A1. Prepare an aniline / sulfuric acid solution with a concentration of 0.005-2 mol / L and an ammonium persulfate / sulfuric acid solution with a concentration of 0.00125-0.5 mol / L, wherein the concentration of sulfuric acid is 0.5-5 mol / L;

[0008] A2. Put the elastic core-spun yarn into the prepared aniline sulfuric acid solution according to a bath ratio of 1:10-200, stir and impregnate it, then pour it into the ammonium persulfate / sulfuric acid solution, and stir and react at a temperature of 0-5 °C for 1-24 h. After that, it is washed with water and dried to obtain the product.

[0009] Preferably, the stirring and impregnation time in A2 is 1-10 minutes; the drying temperature is 50-80 °C, and the drying time is 5-10 minutes.

[0010] Preferably, the preparation method of the MXene / polyaniline nanoarray modified core-spun yarn is to successively impregnate the polyaniline modified elastic core-spun yarn with polydopamine, dry it for the first time, impregnate it with a MXene dispersion liquid, and dry it for the second time. Then, the above two impregnation and corresponding drying processes are repeated to control the loading amount of MXene on the polyaniline nanoarray modified core-spun yarn to be 6-35 wt%.

[0011] Preferably, the concentration of polydopamine is 5-50 mg / mL, and the impregnation time with polydopamine is 1-10 minutes; the concentration of the MXene dispersion liquid is 0.5-50 mg / mL, and the impregnation time with the MXene dispersion liquid is 1-10 minutes.

[0012] Preferably, the drying temperature for the first time and the second time is both 50-80 °C.

[0013] Preferably, the method for synchronously wrapping to prepare a double-wrapped structure strain-insensitive yarn sensor includes the following steps:

[0014] B1. Pre - stretch the MXene / polyaniline nanorod array core - spun yarn as the core yarn by 100% - 1000%, and fix both ends of it.

[0015] B2. Adopt the synchronous wrapping method to wrap the MXene / polyaniline nanorod array core - spun yarn as the sheath yarn on the surface of the core yarn after treatment in B1, and prepare a double - wrapped structure strain - insensitive yarn sensor.

[0016] The elastic core - spun yarn includes cotton core - spun yarn, polyester core - spun yarn, viscose core - spun yarn, and spandex core - spun yarn.

[0017] A strain - insensitive yarn strain sensor is prepared by the described preparation method.

[0018] The present invention also provides the application of the strain - insensitive yarn strain sensor in a stretchable circuit, a flexible supercapacitor, or a stretchable electrothermal device.

[0019] The present invention constructs a polyaniline / MXene composite conductive network structure on the surface of the elastic core - spun yarn by in - situ polymerization of polyaniline nanorods and coating MXene nanosheets; adopts the synchronous wrapping method to wrap the prepared polyaniline nanorod array / MXene elastic core - spun yarn on its surface in a helical structure to form a double - wrapped structure yarn. By virtue of the high conductivity of the core layer and the skin layer and the helical structure of the skin layer, the resistance change caused by the destruction of the conductive network structure during the stretching process of the yarn can be fully reduced, endowing it with the characteristic of strain - resistance insensitivity and realizing its application in high - elasticity electronic circuits.

[0020] The beneficial effects of the present invention:

[0021] 1. The technology of the present invention has strong popularization. The elastic core - spun yarn adopted in the present invention can be cotton core - spun yarn, polyester core - spun yarn, viscose core - spun yarn, spandex core - spun yarn, etc.

[0022] 2. By virtue of the polyaniline nanorod and MXene nanosheet composite conductive network structure, the present invention endows the elastic core - spun yarn with excellent conductivity, and the double - wrapped structure yarn formed after synchronous wrapping also has excellent conductivity.

[0023] 3. The process of the present invention is simple, easy to implement, has low production cost, and is suitable for mass production.

[0024] 4. The double - wrapped structure yarn prepared by the present invention has excellent flexibility and elasticity, and its elastic recovery rate is above 95%.

[0025] 5. The double - wrapped structure yarn prepared by the present invention has excellent strain - resistance insensitivity characteristics, and within the strain range of 400%, the relative resistance change is less than 8%.

[0026] 6. The double - wrapped structure yarn prepared by the present invention can be used as a stretchable supercapacitor due to its strain - insensitive characteristics and has excellent electrochemical performance. Its specific capacitance can be as high as 3.5 mF / cm, and the capacitance changes little with strain.

[0027] 7. The present invention has a wide range of applications. The double - wrapped structure yarn prepared by the present invention can be used in stretchable circuits, flexible supercapacitors, stretchable electrothermal devices, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only those of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a preparation process flow and a structural schematic diagram of the strain - insensitive yarn sensor of the present invention;

[0030] Figure 2 It is a scanning electron microscope image of Example 1, Example 5 and Comparative Example 1;

[0031] Figure 3 It is the elastic recovery rate of Examples 1 - 5 and Comparative Example 1;

[0032] Figure 4 It is a resistance comparison diagram of Examples 1 - 5;

[0033] Figure 5 It is the sensing curve of Examples 1 - 5;

[0034] Figure 6 It is the sensing curve of Example 5 and Comparative Examples 1 - 3;

[0035] Figure 7 It is the specific capacitance curve of Example 5 and Comparative Examples 1 - 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further details the present invention with specific embodiments.

[0037] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "including" or "comprising" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0038] Example 1

[0039] A preparation method of a double-wrapped structure strain-insensitive yarn strain sensor, comprising the following steps:

[0040] 1) Preparation of polyaniline nanoarray-modified core-spun yarn: Prepare aniline / sulfuric acid solution with a concentration of 0.05 mol / L and ammonium persulfate / sulfuric acid solution with a concentration of 0.0125 mol / L respectively, where the concentration of sulfuric acid is 1 mol / L. Put the elastic core-spun yarn into the prepared aniline sulfuric acid solution according to a bath ratio of 1:30, stir and impregnate for 5 minutes, and then quickly pour the above ammonium persulfate solution into the core-spun yarn system. The whole system reacts under stirring at a temperature of 0 °C and a rotation speed of 100 rpm for 24 hours. Then, the prepared polyaniline-modified elastic yarn is washed 3 times with water and dried at 60 °C for 5 minutes.

[0041] 2) Preparation of MXene / polyaniline nanoarray-modified core-spun yarn: First, immerse the polyaniline-modified elastic core-spun yarn prepared in step 1 in polydopamine with a concentration of 10 mg / mL for 5 minutes, dry it at 50 °C, and then immerse it in the MXene dispersion with a concentration of 10 mg / mL for 5 minutes, and then dry it at 60 °C. Repeat the above process to control the loading amount of MXene on the yarn to be 6.7 wt%.

[0042] 3) Preparation of a double-wrapped structure yarn strain sensor: Use the MXene / polyaniline nanoarray core-spun yarn prepared in step 2 as the core yarn, pre-stretch it by 400%, and fix its two ends. At the same time, use the MXene / polyaniline nanoarray core-spun yarn as the sheath yarn, and use the synchronous wrapping method to wrap the sheath yarn on the surface of the core yarn to obtain a double-wrapped structure strain-insensitive yarn sensor.

[0043] Example 2

[0044] A preparation method of a double-wrapped structure strain-insensitive yarn strain sensor, comprising the following steps:

[0045] 1) Preparation of polyaniline nanoarray modified core-spun yarn: Prepare aniline / sulfuric acid solution with a concentration of 0.05 mol / L and ammonium persulfate / sulfuric acid solution with a concentration of 0.0125 mol / L respectively, where the concentration of sulfuric acid is 1 mol / L. Put the elastic core-spun yarn into the prepared aniline sulfuric acid solution according to a bath ratio of 1:30, stir and impregnate for 5 minutes, then quickly pour the above ammonium persulfate solution into the core-spun yarn system. The whole system is stirred and reacted at 0 °C and 100 rpm for 24 hours. Then, the prepared polyaniline modified elastic yarn is washed 3 times with water and dried at 60 °C for 5 minutes.

[0046] 2) Preparation of MXene / polyaniline nanoarray modified core-spun yarn: First, immerse the polyaniline modified elastic core-spun yarn prepared in step 1 in polydopamine with a concentration of 10 mg / mL for 5 minutes. After drying at 50 °C, immerse it in the MXene dispersion with a concentration of 10 mg / mL for 5 minutes, and then dry at 60 °C. Repeat the above process to control the loading amount of MXene on the yarn to be 13.3 wt%.

[0047] 3) Preparation of double-covered structure yarn strain sensor: Use the MXene / polyaniline nanoarray core-spun yarn prepared in step 2 as the core yarn, pre-stretch it by 400%, and fix its two ends. At the same time, use the MXene / polyaniline nanoarray core-spun yarn as the skin yarn, and wrap the skin yarn on the surface of the core yarn by the synchronous covering method to prepare a double-covered structure strain-insensitive yarn sensor.

[0048] Example 3

[0049] A preparation method of a double-covered structure strain-insensitive yarn strain sensor, comprising the following steps:

[0050] 1) Preparation of polyaniline nanoarray modified core-spun yarn: Prepare aniline / sulfuric acid solution with a concentration of 0.05 mol / L and ammonium persulfate / sulfuric acid solution with a concentration of 0.0125 mol / L respectively, where the concentration of sulfuric acid is 1 mol / L. Put the elastic core-spun yarn into the prepared aniline sulfuric acid solution according to a bath ratio of 1:30, stir and impregnate for 5 minutes, then quickly pour the above ammonium persulfate solution into the core-spun yarn system. The whole system is stirred and reacted at 0 °C and 100 rpm for 24 hours. Then, the prepared polyaniline modified elastic yarn is washed 3 times with water and dried at 60 °C for 5 minutes.

[0051] 2) Preparation of MXene / polyaniline nanorod array modified core-spun yarn: The polyaniline modified elastic core-spun yarn prepared in step 1 was first immersed in polydopamine with a concentration of 10 mg / mL for 5 minutes, dried at 50 °C, then immersed in an MXene dispersion with a concentration of 10 mg / mL for 5 minutes, and then dried at 60 °C. The above process was repeated to control the loading amount of MXene on the yarn to be 20.0 wt%.

[0052] 3) Preparation of double-covered structure yarn strain sensor: The MXene / polyaniline nanorod array core-spun yarn prepared in step 2 was used as the core yarn, pre-stretched by 400%, and its two ends were fixed. At the same time, the MXene / polyaniline nanorod array core-spun yarn was used as the sheath yarn, and the sheath yarn was wrapped around the surface of the core yarn by the synchronous covering method to obtain a double-covered structure strain-insensitive yarn sensor.

[0053] Example 4

[0054] A preparation method of a double-covered structure strain-insensitive yarn strain sensor includes the following steps:

[0055] 1) Preparation of polyaniline nanorod array modified core-spun yarn: An aniline / sulfuric acid solution with a concentration of 0.05 mol / L and an ammonium persulfate / sulfuric acid solution with a concentration of 0.0125 mol / L were respectively prepared, where the concentration of sulfuric acid was 1 mol / L. The elastic core-spun yarn was put into the prepared aniline sulfuric acid solution according to a bath ratio of 1:30, stirred and immersed for 5 minutes, and then the above ammonium persulfate solution was quickly poured into the core-spun yarn system. The whole system was stirred and reacted at 0 °C and 100 rpm for 24 hours. Then, the prepared polyaniline modified elastic yarn was washed 3 times with water and dried at 60 °C for 5 minutes.

[0056] 2) Preparation of MXene / polyaniline nanorod array modified core-spun yarn: The polyaniline modified elastic core-spun yarn prepared in step 1 was first immersed in polydopamine with a concentration of 10 mg / mL for 5 minutes, dried at 50 °C, then immersed in an MXene dispersion with a concentration of 10 mg / mL for 5 minutes, and then dried at 60 °C. The above process was repeated to control the loading amount of MXene on the yarn to be 26.7 wt%.

[0057] 3) Preparation of double-covered structure yarn strain sensor: The MXene / polyaniline nanorod array core-spun yarn prepared in step 2 was used as the core yarn, pre-stretched by 400%, and its two ends were fixed. At the same time, the MXene / polyaniline nanorod array core-spun yarn was used as the sheath yarn, and the sheath yarn was wrapped around the surface of the core yarn by the synchronous covering method to obtain a double-covered structure strain-insensitive yarn sensor.

[0058] Example 5

[0059] A preparation method of a double - wrapped structure strain - insensitive yarn strain sensor, comprising the following steps:

[0060] 1) Preparation of polyaniline nanoarray - modified core - spun yarn: Prepare aniline / sulfuric acid solution with a concentration of 0.05 mol / L and ammonium persulfate / sulfuric acid solution with a concentration of 0.0125 mol / L respectively, where the concentration of sulfuric acid is 1 mol / L. Put the elastic core - spun yarn into the prepared aniline - sulfuric acid solution according to a bath ratio of 1:30, stir and impregnate for 5 minutes, then quickly pour the above - mentioned ammonium persulfate solution into the core - spun yarn system. The whole system is stirred and reacted at a temperature of 0 °C and a rotation speed of 100 rpm for 24 hours. Then, the prepared polyaniline - modified elastic yarn is washed 3 times with water and dried at 60 °C for 5 minutes.

[0061] 2) Preparation of MXene / polyaniline nanoarray - modified core - spun yarn: First, immerse the polyaniline - modified elastic core - spun yarn prepared in step 1 in polydopamine with a concentration of 10 mg / mL for 5 minutes, dry it at 50 °C, then immerse it in the MXene dispersion liquid with a concentration of 10 mg / mL for 5 minutes, and then dry it at 60 °C. Repeat the above process to control the loading amount of MXene on the yarn to be 33.3 wt%.

[0062] 3) Preparation of a double - wrapped structure yarn strain sensor: Use the MXene / polyaniline nanoarray core - spun yarn prepared in step 2 as the core yarn, pre - stretch it by 400%, and fix its two ends. At the same time, use the MXene / polyaniline nanoarray core - spun yarn as the sheath yarn, and use the synchronous wrapping method to wrap the sheath yarn on the surface of the core yarn to obtain a double - wrapped structure strain - insensitive yarn sensor.

[0063] Comparative Example 1

[0064] A preparation method of a double - wrapped structure strain - insensitive yarn strain sensor, comprising the following steps:

[0065] 1) Preparation of polyaniline nanoarray - modified core - spun yarn: The same as in Example 5.

[0066] 2) Preparation of MXene / polyaniline nanoarray - modified core - spun yarn: The same as in Example 5.<SHAPE>

[0067] 3) Preparation of the yarn strain sensor: Use the yarn prepared in step 2) directly as the strain sensor.

[0068] Comparative Example 2

[0069] A preparation method of a double - wrapped structure strain - insensitive yarn strain sensor, comprising the following steps:

[0070] 1) Preparation of polyaniline nanoarray - modified core - spun yarn: The same as in Example 5.

[0071] 2) Preparation of MXene / polyaniline nanorod array modified core-spun yarn: The same as in Example 5.

[0072] 3) Preparation of yarn strain sensor: The same as in Example 5, except that the core yarn is changed to an insulating elastic core-spun yarn.

[0073] Comparative Example 3

[0074] A preparation method of a double wrapped structure strain-insensitive yarn strain sensor includes the following steps:

[0075] 1) Preparation of polyaniline nanorod array modified core-spun yarn: The same as in Example 5.

[0076] 2) Preparation of MXene / polyaniline nanorod array modified core-spun yarn: The same as in Example 5.

[0077] 3) Preparation of double wrapped structure yarn strain sensor: The same as in Example 5, except that the yarn in step 1) is used as the core yarn.

[0078] The double wrapped structure yarn strain sensor prepared by the synchronous wrapping method adopted in the present invention has a structure as Figure 1 shown. The core layer of the yarn is a highly conductive elastic core-spun yarn structure, and the skin layer is a helical structure highly elastic core-spun yarn. Since the core layer yarn is subjected to high strain pre-elongation treatment during the preparation process, the skin layer yarn will be wrapped around the yarn surface in a highly coiled helical structure, ensuring that the yarn always maintains a highly conductive network structure during the stretching process and endowing the yarn with strain-insensitive characteristics. Since both the core layer and the outer layer of the yarn are highly conductive structures, it can ensure the high-speed transfer of electrons along the axial and radial directions of the yarn. In addition, on the one hand, the helical structure yarn of the skin layer increases the yarn diameter and reduces the yarn body resistance, and on the other hand, due to the coil structure, the contact resistance between the skin layer and the core layer yarn can be fully reduced. Therefore, the finally prepared yarn will have excellent strain-insensitive characteristics.

[0079] The scanning electron microscope images of Example 1, Example 5 and Comparative Example 1 are as Figure 2 shown. It can be seen that a certain number of MXene nanosheets have been loaded on the fiber surface in Example 1, and only a small amount of polyaniline nanorod arrays are exposed on the fiber surface; the skin layer yarn in Example 5 is wrapped around the core yarn surface in a helical structure, and the fiber surface has been completely wrapped by MXene nanosheets to form a MXene film. In Comparative Example 1, the fiber surface in the yarn is also completely wrapped by MXene nanosheets to form a MXene film. The loading amount of MXene in Example 5 and Comparative Example 1 is significantly higher than that in Example 1, and the formed MXene film is more complete. This is mainly because more MXene loading cycles are carried out in Example 5 and Comparative Example 1, resulting in a higher loading amount of MXene.

[0080] The elastic recovery rates of Examples 1-5 and Comparative Example 1 were tested.

[0081] The test results are as Figure 3 shown. The elastic recovery rates of Examples 1-5 are all above 95%, showing good elastic elongation and less irreversible deformation. While the elastic recovery rate of Comparative Example 1 is only 75% with more irreversible deformation. This is mainly because the yarns prepared by the synchronous wrapping method in Examples 1-5 have a double wrapping structure, and the deformation during the stretching process is converted into an increase or decrease in the yarn pitch, without deteriorating the elasticity of the fiber. In addition, the pre-elongation effect of the core yarn during the synchronous wrapping process also helps to improve the elasticity and elastic recovery of the yarn.

[0082] Resistance test of Examples 1-5

[0083] The test results are as Figure 4 shown. It can be seen that the resistance of the yarns in Examples 1-5 decreases with the increase of the MXene loading amount. The resistance of the yarn in Example 5 is the lowest at 20 Ω / cm. This is mainly because the increase in the MXene loading amount establishes more conductive paths inside the yarn, endowing the yarn with more excellent conductive performance.

[0084] Sensing test

[0085] The test results of Examples 1-5 are as Figure 5 shown. It can be seen from Figure 5 that when Examples 1-5 are stretched to 400%, their relative resistance change rates are 75%, 40%, 30%, 16.5%, and 8% respectively, and the corresponding sensing coefficients (GF = relative resistance change rate / strain rate * 100%) are 18.75%, 10%, 7.5%, 4.1%, and 2% respectively. Example 5 has the smallest strain sensing coefficient. This indicates that the resistance of the strain sensor of the double-wrapped structure yarn prepared in Example 5 changes less with the stretching strain and is more suitable for stretchable electronic circuits. Its excellent strain resistance insensitivity performance is mainly because both the core layer and the skin layer use polyaniline nanoarray / MXene elastic core-spun yarns with high electrical conductivity, endowing the yarn with excellent electrical conductivity. In addition, due to the pre-stretching effect of the core layer, the high-conductivity yarn in the skin layer is wrapped around the yarn surface in a helical structure. On the one hand, the yarn resistance is reduced by increasing the yarn diameter. On the other hand, the yarn deformation during the stretching process will be converted into a change in the pitch of the skin layer yarn. Therefore, Example 5 has the best strain resistance insensitivity performance.

[0086] The sensing test results of Example 5 and Comparative Examples 1-3 are as Figure 6 shown. It can be seen from Figure 6It can be seen that when the comparative examples 1-3 are stretched to 400%, the relative resistance change rates of the yarns are 1000%, 450%, and 120% respectively, and the corresponding sensing coefficients are 250%, 112.5%, and 30% respectively. The sensing coefficients of the comparative examples are all higher than that of Example 5 (2%). The main reason for the highest sensing coefficient of Comparative Example 1 is that it does not adopt a double wrapping structure, resulting in more damage to the conductive network due to the elongation of the yarn during the stretching process, and a larger change in resistance; the relatively low sensing coefficient of Comparative Example 3 is mainly due to its adoption of a double wrapping structure, but due to the low conductivity of the yarn used in the core layer, the resistance of the yarn is relatively high, and the strain resistance insensitivity performance is lower than that of Example 5.

[0087] Electrochemical test

[0088] Such as Figure 7 Figure 8 shows the specific capacitance curves of Example 5 and Comparative Examples 1-3. From Figure 7 it can be seen that the specific capacitance of Comparative Examples 1-3 decreases rapidly with the increase of the tensile strain. Among them, when the tensile strain of Comparative Example 1 increases to 300%, the specific capacitance decreases significantly, and the specific capacitance is only 5.7% of the initial state. The main reason for the significant decrease in its specific capacitance with the increase of the tensile strain is that the conductive path inside the yarn is damaged during stretching, resulting in a significant increase in the resistance of the yarn, and more energy is lost due to impedance; when the tensile strain of Example 5 increases to 300%, the specific capacitance retention rate is as high as 85.7%, showing excellent electrochemical performance. This is mainly because its double wrapping structure endows it with the characteristic of strain resistance insensitivity, generating less impedance loss.

[0089] Those of ordinary skill in the art should understand that the discussion of any above embodiment is only exemplary, and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail.

[0090] The present invention aims to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a strain-insensitive yarn strain sensor, characterized in that, The preparation method is to in-situ grow polyaniline nanoarrays on the surface of elastic core-spun yarn to obtain polyaniline nanoarray modified core-spun yarn, then deposit MXene nanosheets to obtain MXene / polyaniline nanoarray modified core-spun yarn, and then use the MXene / polyaniline nanoarray modified core-spun yarn as the core yarn and the skin yarn, and synchronously wrap them to prepare a double-wrapped structure strain-insensitive yarn sensor; the preparation method of the MXene / polyaniline nanoarray modified core-spun yarn is to sequentially impregnate the polyaniline modified elastic core-spun yarn with polydopamine, dry it once, impregnate it with MXene dispersion liquid, and dry it twice, and then repeat the impregnation and the corresponding drying process twice to control the loading amount of MXene on the polyaniline nanoarray modified core-spun yarn to be 6-35 wt%; The method for synchronously wrapping to prepare a double-wrapped structure strain-insensitive yarn sensor includes the following steps: B1. Pre-stretch the MXene / polyaniline nanoarray core-spun yarn as the core yarn by 100%-1000%, and fix its two ends; B2. Use the method of synchronous wrapping to wrap the MXene / polyaniline nanoarray core-spun yarn as the skin yarn on the surface of the core yarn after treatment in B1 to prepare a double-wrapped structure strain-insensitive yarn sensor.

2. The preparation method of the strain-insensitive yarn strain sensor according to claim 1, characterized in that, The preparation method of the polyaniline nanoarray modified core-spun yarn includes the following steps: A1. Respectively prepare aniline / sulfuric acid solution with a concentration of 0.005-2 mol / L and ammonium persulfate / sulfuric acid solution with a concentration of 0.00125-0.5 mol / L, wherein the concentration of sulfuric acid is 0.5-5 mol / L; A2. Put the elastic core-spun yarn into the prepared aniline / sulfuric acid solution according to a bath ratio of 1:10-200, stir and impregnate it, then pour it into the ammonium persulfate / sulfuric acid solution, and stir and react at a temperature of 0-5°C for 1-24 h, and then wash and dry it to obtain.

3. The method for preparing a strain-insensitive yarn strain sensor according to claim 2, characterized in that, In A2, the stirring and impregnation time is 1-10 minutes; the drying temperature is 50-80°C, and the time is 5-10 minutes.

4. The preparation method of the strain-insensitive yarn strain sensor according to claim 1, characterized in that, The concentration of the polydopamine is 5-50 mg / mL, and the impregnation time of the polydopamine is 1-10 minutes; the concentration of the MXene dispersion liquid is 0.5-50 mg / mL, and the impregnation time of the MXene dispersion liquid is 1-10 minutes.

5. The preparation method of the strain-insensitive yarn strain sensor according to claim 1, wherein, The temperatures of the first drying and the second drying are both 50-80°C.

6. The preparation method of the strain-insensitive yarn strain sensor according to claim 1, characterized in that, The elastic core-spun yarn includes cotton core-spun yarn, polyester core-spun yarn, viscose core-spun yarn, and spandex core-spun yarn.

7. A strain-insensitive yarn strain sensor, characterized in that, Prepared by using the preparation method according to any one of claims 1-6.

8. Application of the strain-insensitive yarn strain sensor according to claim 7 in a stretchable circuit, a flexible supercapacitor or a stretchable electrothermal device.

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