Composite sensing yarn with high sensitivity factor and preparation method thereof

Abstract

The invention discloses a preparation method of a composite sensing yarn with a high sensitivity factor. The preparation method comprises the following steps: pre-treating a flexible base material; preparation of a conductive solution: preparing a silver nanowire / graphene oxide mixed conductive solution from graphene oxide and silver nanowires; preparing a composite sensing yarn, soaking the pretreated polyurethane yarn in a silver nanowire / graphene oxide mixed conductive solution, and increasing the weight of the treated yarn by 14-16%; and reducing graphene oxide, namely putting the polyurethane yarn treated by the conductive liquid into a vitamin C solution, and heating to react for not less than 20 hours to obtain the composite sensing yarn. The composite sensing yarn prepared through the method has better sensitivity factors and can be more efficiently applied to intelligent wearing and related fields, in addition, the durability of the composite sensing yarn in the sensing performance aspect is remarkably improved, and meanwhile the preparation method is simple.

Description

Technical Field

[0001] This invention belongs to the field of functional textiles and relates to a strain-sensing yarn with high sensitivity and its preparation method. Background Technology

[0002] Sensing yarn is a textile material that can integrate sensor functionality and has broad application potential. For example, in health monitoring of wearable devices, sensing yarn can be integrated into clothing to monitor human physiological parameters in real time, including heart rate, respiratory rate, and body temperature. In the field of sports monitoring, sensing yarn can be used to track athletes' movements and postures, aiding in performance analysis. In the field of smart clothing, sensing yarn can be interwoven with ordinary yarn to create smart garments with heating, sensing, and energy harvesting functions. For instance, honeycomb structure fabrics made with conductive yarns not only have photothermal and electrothermal conversion capabilities but can also be remotely controlled via smartphones. Furthermore, sensing yarn can also be applied to information collection and monitoring in the medical and industrial fields.

[0003] Traditional conductive substrates are typically metal foils or semiconductor materials, but their inherent properties lead to problems such as poor deformation capacity and narrow detection range. Currently, the main approach is to address these issues by fabricating conductive layers on flexible substrates. Sensing materials primarily include carbon nanomaterials, metal nanomaterials, and two-dimensional transition metal carbon / nitrogen compounds (MXene). Graphene oxide is chosen for its good dispersibility, but its poor conductivity necessitates reduction to reduced graphene oxide before it can be applied to sensor surfaces. The commonly used method is the hydrazine hydrate reduction method, but hydrazine hydrate itself is highly hazardous and pollutes the environment. Furthermore, this method easily damages the conductive network of the sensing yarn, reducing conductivity and thus limiting sensor performance. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides a method for preparing a high-sensitivity composite sensing yarn, which improves the stability of the conductive network of the composite sensing yarn, ensures the high sensitivity of the composite sensing yarn, and significantly improves its durability.

[0005] This invention uses silver nanowires with a high aspect ratio as one of the conductive materials. When these silver nanowires with a high aspect ratio form a conductive grid in the composite sensing yarn, they can ensure the stability of the conductive network. In particular, during the stretching and retraction of the composite sensing yarn, the high aspect ratio characteristic maintains the conductivity of the composite sensing yarn.

[0006] Furthermore, the present invention uses a specific processing technique to increase the adhesion between the flexible substrate and the conductive material in the composite sensing yarn. At the same time, the properties of the conductive material can effectively form a dense conductive network, thereby improving the sensitivity factor of the composite sensing yarn.

[0007] Furthermore, this invention improves the dispersion performance of the conductive solution through unified adjustment, while using a milder reducing agent to reduce graphene oxide, thereby improving the conductivity of the conductive material on the flexible material.

[0008] To achieve the above objectives, in a first aspect of the present invention, a method for preparing a composite sensing yarn with a high sensitivity factor is provided, comprising the following steps: Step 1, Pretreatment of flexible substrate: Polyurethane yarn is immersed in an organic solvent to remove impurities from the surface of the polyurethane yarn, and then subjected to plasma treatment. Step 2, Preparation of conductive solution: Add graphene oxide powder to deionized water and disperse it by ultrasonication. Adjust the pH of the graphene oxide dispersion with ammonia water to obtain a graphene oxide dispersion. Take the silver nanowire dispersion prepared by the polyol method and mix it with the graphene oxide dispersion to obtain a silver nanowire / graphene oxide mixed conductive solution. Step 3, Preparation of composite sensing yarn: The pretreated polyurethane yarn in step 1 is immersed in the silver nanowire / graphene oxide mixed conductive solution in step 2, then taken out and dried to obtain polyurethane yarn treated with conductive liquid. Step 4, Reduction of graphene oxide: The polyurethane yarn treated with conductive liquid in step 3 is placed in vitamin C solution, heated to react, and dried to obtain composite sensing yarn.

[0009] Preferably, in step 1, the organic solvent is ethanol or acetone; the treatment time of the organic solvent is 10-60 min; preferably 20-40 min. In step 1, the polyurethane yarn is immersed in the organic solvent and impurities are removed using ultrasonic assistance; the ultrasonic removal time is 20-40 minutes.

[0010] Preferably, in step 1, after removing impurities from the surface of the polyurethane yarn, it is dried to keep the polyurethane yarn dry; the drying temperature is 70-90℃. In step 1, after removing impurities from the surface of the polyurethane yarn, plasma treatment is performed; the plasma treatment time is 2-15 min; preferably 3-10 min.

[0011] Preferably, in step 2, the graphene oxide powder is added to deionized water and ultrasonically dispersed, wherein the concentration of the graphene oxide is 0.1%-2% by mass / volume; and the pH of the graphene oxide dispersion is adjusted to 6-8 using ammonia. Preferably, in step 2, the silver nanowire dispersion prepared by the polyol method is mixed with the graphene oxide dispersion, and the volume ratio of the amount of silver nanowire dispersion to the volume of graphene oxide dispersion is (4-6):5. The silver nanowire dispersion and the graphene oxide dispersion are mixed using ultrasonic dispersion assistance, and the ultrasonic dispersion time is 10-60 min.

[0012] Preferably, in step 3, the polyurethane yarn treated with conductive liquid is subjected to repeated impregnation to increase in weight by 14%-16% compared to the untreated polyurethane yarn in step (1).

[0013] Preferably, in step 4, the concentration of the vitamin C solution is 8-20 mg / mL.

[0014] Preferably, in step 4, the temperature of the heating reaction is 85-100°C.

[0015] Preferably, in step 4, the heating reaction time is not less than 20 hours.

[0016] In another aspect of the present invention, a composite sensing yarn with a high sensitivity factor is provided, which is prepared according to the preparation method described in the first aspect of the present invention.

[0017] Compared with the prior art, the superior effects of the present invention are that the prepared composite sensing yarn has a better sensitivity factor, which can be applied to smart wearables and related fields more efficiently. In addition, the durability of the yarn in terms of sensing performance is significantly improved, and the preparation method is simple. Attached Figure Description

[0018] Figure 1 The resistivity change rate of the composite sensing yarn prepared in this invention -Strain curve; Figure 2 The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared for this invention under different strains. Figure 3 The resistivity change rate of the composite sensing yarn prepared in this invention when repeatedly stretched 4500 times at 10% strain; Figure 4 A schematic diagram illustrating the wearable application of the composite sensing yarn prepared in this invention; Figure 5 This is a microscopic electron microscope image of the composite sensing yarn prepared according to the present invention. Figure 6 The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared for Comparative Example 1 under different strains. Figure 7The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared in Comparative Example 2 under different strains were studied. Figure 8 The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared in Comparative Example 3 under different strains. Figure 9 The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared in Comparative Example 4 under different strains. Figure 10 The relative resistance change and sensitivity (GF) of the composite sensing yarns prepared for Comparative Examples 5 and 6 under different strains. Detailed Implementation

[0019] 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. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0020] To achieve the objective of this invention, a method for preparing a composite sensing yarn with a high sensitivity factor is provided, comprising the following steps: Step 1: Pretreatment of flexible substrate: The polyurethane yarn is immersed in an organic solvent to remove impurities from the yarn surface; the polyurethane yarn after impurity removal is then subjected to plasma treatment. The organic solvent in step 1 is ethanol or acetone; preferably anhydrous ethanol. The treatment time using organic solvents is 10-60 min, preferably 20-40 min, and more preferably 25-35 min; Organic solvents can effectively remove grease and other substances from polyurethane yarns. Since polyurethane yarns are primarily composed of synthetic fibers, a certain amount of oil is typically added during fiber manufacturing to prevent static electricity. Therefore, the grease needs to be removed before treatment to prevent the adsorption of conductive substances from the conductive solution onto the polyurethane yarn. Furthermore, because most greases are insulating, they can negatively impact the conductivity of the conductive network on the polyurethane yarn to some extent.

[0021] Furthermore, in step 1, the polyurethane yarn is impregnated in an organic solvent and impurities are removed using ultrasonic assistance. The time for ultrasonic-assisted impurity removal is 20-40 minutes, preferably 25-35 minutes.

[0022] Furthermore, after removing impurities from the surface of the polyurethane yarn, it is dried to keep the yarn dry. The drying temperature is 70-90℃, preferably 80℃.

[0023] Furthermore, in step 1, the polyurethane yarn, after being treated with organic solvent and dried, undergoes plasma treatment. The plasma treatment time is 2-15 min, preferably 3-10 min.

[0024] Plasma treatment can effectively improve the activity of polyurethane yarn, giving the yarn surface more anchor points that can bond with conductive materials.

[0025] Step 2, Preparation of the conductive solution: Graphene oxide powder was added to deionized water and ultrasonically dispersed. The pH of the graphene oxide dispersion was adjusted with ammonia. The silver nanowire dispersion prepared by the polyol method was mixed with the graphene oxide dispersion and dispersed to obtain a silver nanowire / graphene oxide mixed conductive solution.

[0026] It should be noted that step 2 is the preparation of the conductive solution, which is an independent step. Therefore, step 2 is not limited to being after step 1 or before subsequent steps. In actual operation, those skilled in the art can adjust the preparation process of the conductive liquid in step 2 as needed.

[0027] Step 2 involves adding graphene oxide powder to deionized water and ultrasonically dispersing it. The pH of the graphene oxide dispersion is adjusted using ammonia. The silver nanowire dispersion prepared by the polyol method is mixed with the graphene oxide dispersion and dispersed to obtain a silver nanowire / graphene oxide mixed conductive solution.

[0028] The amount of graphene oxide powder added to deionized water is 0.1%-2% by mass volume; preferably, the amount of graphene oxide is 0.5%-1% by mass volume (w / v); for example, the amount of graphene oxide can be 0.5% (w / v), 1.0% (w / v), or 1.5% (w / v).

[0029] It should be noted that the amount of graphene used is in a mass ratio of water to water, which is a mass-volume percentage. That is, graphene is expressed in units of mass, and water in units of volume.

[0030] The pH of the graphene oxide dispersion is preferably adjusted to 6-8 using ammonia; more preferably, pH 7.

[0031] It should be noted that when using ammonia to adjust the pH of a solution, a pH of 7 does not mean that it is an exact pH of 7, but rather that a limited fluctuation is allowed around pH=7.

[0032] The volume ratio of silver nanowire dispersion to graphene dispersion is (4-6):5, preferably 1:1.

[0033] The preparation process of the silver nanowire dispersion includes: preparing two beakers; weighing 40 mL of ethylene glycol; adding 0.3 g of polyvinylpyrrolidone powder to the beaker containing 40 mL of ethylene glycol; and magnetically stirring to accelerate the dissolution rate. Then, adding 10 mL of ethylene glycol and 0.2 g of silver nitrate to the other beaker and ultrasonically dissolving them thoroughly; adding the completely dissolved silver nitrate ethylene glycol solution to the 40 mL polyvinylpyrrolidone ethylene glycol solution; and magnetically stirring to mix the solution. Adding prepared sodium chloride ethylene glycol solutions and sodium bromide ethylene glycol solutions at a molar ratio of sodium chloride / sodium bromide = 19:1 to the mixture from the previous step. Transferring the mixture to a hydrothermal reactor and reacting at 130 °C for 8 hours. Adding anhydrous ethanol to the resulting solid-liquid mixture after the reaction; washing and purifying the mixture in a centrifuge at 4000 r / min; and finally, dispersing the centrifuged purified AgNWs in deionized water for storage for later use.

[0034] When mixing the silver nanowire dispersion and the graphene oxide dispersion, ultrasonic dispersion is used as an aid. The ultrasonic dispersion time is 10-60 min, and the preferred ultrasonic dispersion time is 20-40 min.

[0035] Step 3: Preparation of composite sensing yarn: Specifically, the pretreated polyurethane yarn in step 1 is immersed in the silver nanowire / graphene oxide mixed conductive solution in step 2, then taken out and dried to obtain polyurethane yarn treated with conductive liquid. Among them, the weight gain percentage of the sensing yarn after repeated impregnation and drying treatment is 14%-16% compared to the original polyurethane yarn, resulting in the final polyurethane yarn treated with conductive liquid.

[0036] Furthermore, in order to achieve a weight gain of 14%-16% for the treated polyurethane yarn compared to the original polyurethane yarn, a repeated impregnation step is adopted, that is, the polyurethane yarn treated with the conductive liquid is repeatedly immersed in the silver nanowire / graphene oxide mixed conductive solution in step 2.

[0037] Step 4, Reduction of graphene oxide: The polyurethane yarn treated with conductive liquid obtained in step 3 is placed in a vitamin C solution, heated to react, and then dried to obtain a composite sensing yarn.

[0038] The concentration of vitamin C in the solution is 8-20 mg / mL, preferably 10 mg / mL; The heating reaction temperature is 85-100℃, preferably 90℃; The heating reaction time should be no less than 20 hours, preferably 24 hours, to ensure that the graphene oxide is fully reduced.

[0039] In this invention, in step 2, graphene oxide is used as a dispersion liquid mainly because graphene oxide has a certain degree of hydrophilicity and can be effectively dispersed in aqueous solution. In step 3, the conductive material can be deposited on the polyurethane yarn through a common impregnation method. In step 4, the problem of uneven dispersion of reduced graphene oxide can be solved by treating the yarn surface with graphene oxide and then reducing the yarn. At the same time, the use of vitamin C also meets the conditions for green preparation.

[0040] Specifically, the present invention provides the following embodiments and comparative examples: Example 1 A method for preparing a composite sensing yarn with high sensitivity is carried out according to the following steps: Step 1: Pretreatment of the flexible substrate: The polyurethane yarn is immersed in anhydrous ethanol solution for 30 minutes and ultrasonically treated to remove impurities and dust from the yarn surface. Then it is dried in a 60°C oven for 6 minutes. The dried yarn is then treated with plasma for 3 minutes. The treated yarn is then cut to obtain the flexible substrate required for the experiment. Step 2, Preparation of conductive solution: 50 mg of graphene oxide powder was added to 10 mL of deionized water and ultrasonically dispersed for 30 min to obtain a uniformly dispersed 5 mg / mL graphene oxide dispersion; then, the pH of the graphene oxide dispersion was adjusted to about 7 using ammonia; 10 mL of silver nanowire dispersion prepared by the polyol method was mixed with the graphene oxide dispersion and ultrasonicated for 30 min to obtain a silver nanowire / graphene oxide mixed conductive solution.

[0041] Step 3, Preparation of composite sensing yarn: The yarn cut in step (1) is immersed in a mixed conductive solution of graphene oxide / silver nanowires, then removed and dried in an oven at 60°C for 7 minutes. The above steps are repeated to obtain silver nanowire / graphene oxide composite conductive yarn; the weight gain percentage of the sensing yarn after repeated immersion and drying treatment compared with the original polyurethane yarn is 14%-16%; Step 4: Prepare a 10 mg / mL VC aqueous solution. Put the composite yarn obtained in step (3) and VC into a hydrothermal reactor and react at 90°C for 24 h. Then take out the yarn and dry it in a 60°C oven for 10 min to obtain the silver nanowire / reduced graphene oxide composite sensing yarn.

[0042] Comparative Example 1 The steps are the same as in Example 1, except that in step 2, the ratio of the uniformly dispersed 5 mg / mL graphene oxide dispersion to the silver nanowire dispersion is adjusted. Specifically, the volume ratio of graphene oxide dispersion to silver nanowire dispersion is 2:1.

[0043] Comparative Example 2 The basic steps and parameters are the same as in Example 1. The difference is that in step 2, the ratio of the uniformly dispersed 5 mg / mL graphene oxide dispersion to the silver nanowire dispersion is adjusted. Specifically, the volume ratio of graphene oxide dispersion to silver nanowire dispersion is 1:2.

[0044] Comparative Example 3 The basic steps and parameters are the same as in Example 1, except that the reduction time of vitamin C in step 4 is set to 8 hours and 16 hours.

[0045] Comparative Example 4 The basic steps and parameters are the same as in Example 1, except that the fibers in step 1 are not subjected to plasma treatment.

[0046] Comparative Example 5 The basic steps and parameters are the same as in Example 1, except that the fiber impregnation is performed 5 times in step 3.

[0047] Comparative Example 6 The basic steps and parameters are the same as in Example 1, except that the fiber impregnation is repeated 15 times in step 3.

[0048] The sensing yarns obtained in Example 1 and Comparative Examples 1-4 were subjected to performance tests. During the tests, sensitivity (GF) was a crucial indicator for evaluating sensor sensitivity; higher sensitivity meant a stronger signal transmission capability. The formula for calculating GF is: , where R is the resistance of the yarn under the current tensile state, R0 is the initial resistance of the yarn, and ε is the strain of the yarn.

[0049] Specifically, Figure 1 The rate of change of resistance of the composite sensing yarn prepared in Example 1 -Strain curve; Figure 2 The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared in Example 1 under different strains. Figure 3 The resistance change rate of the composite sensing yarn prepared in Example 1 when repeatedly stretched 4500 times at 10% strain; Figure 4 A schematic diagram of the wearable application of the composite sensing yarn prepared in Example 1; Figure 5 This is a micro-electron micrograph of the composite sensing yarn prepared in Example 1; Figure 6The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared for Comparative Example 1 under different strains. Figure 7 The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared in Comparative Example 2 under different strains were studied. Figure 8 The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared in Comparative Example 3 under different strains. Figure 9 The relative resistance change and sensitivity (GF) of the composite sensing yarn prepared in Comparative Example 4 under different strains. Figure 10 The relative resistance change and sensitivity (GF) of the composite sensing yarns prepared for Comparative Examples 5 and 6 under different strains.

[0050] in, Figure 1 It can be seen that the composite yarn prepared in Example 1 shows that as the strain gradually increases from 4% to 60%, the composite yarn... It gradually rises to around 500, and as the stretching cycle continues, the yarn... There are also periodic changes; as the stretching range increases, the yarn... It will fluctuate within a certain range, but it still exhibits a periodic pattern of change.

[0051] And in Figure 2 In the test, the composite yarn showed a sensitivity of 600 in the 1%-30% stretch range and 5580 in the 30%-60% stretch range, indicating that the sensing yarn has good strain response capability and that the yarn sensitivity gradually increases with the increase of the stretch range.

[0052] exist Figure 3 In the initial stretching stage, the relative resistance of the composite yarn begins to decrease to a certain extent. This is because as stretching progresses, slippage occurs between the reduced graphene oxide sheets. The presence of silver nanowires alters the microstructure of the conductive network, maintaining a balance between fracture and reconstruction. Although a slight deterioration in sensor performance was observed after cyclic durability testing, our strain sensor still exhibits superior strain sensing characteristics.

[0053] Figure 4 In this context, the potential wearable applications of composite-sensing yarns include attaching strain-sensing yarns to the hand joints and elbows to monitor varying degrees of human movement. For example, when the hand makes a fist-clenching motion... It exhibits a unique variation curve and has good repeatability; when the elbow begins to move, The value changes with the movement of the elbow and exhibits good cyclical performance. The value is also related to the range of motion of the elbow; the greater the range of motion, the higher the value. The larger the size, the smaller the range of motion. The smaller it is.

[0054] exist Figure 5 In the study, electron micrographs of the composite yarns were examined, including those from... Figure 5 (a) It can be seen that the surface of the polyurethane yarn is coated with a layer of wrinkled composite conductive network composed of graphene oxide / silver nanowires. Figure 5 (b) It can be clearly seen that the silver nanowires are interwoven within the graphene oxide sheets, from Figure 5 (c, d) It can be seen that the fiber surface becomes smooth after reduction, indicating that graphene oxide was successfully reduced to reduced graphene oxide, and formed a stable and strong three-dimensional conductive network with silver nanowires.

[0055] See Figure 6 The performance of the composite yarn obtained in Comparative Example 1 shows that the detection range of the yarn in Comparative Example 1 is 0-40%, which is lower than that in Example 1, and its sensitivity is also reduced to a certain extent.

[0056] Additionally, see Figure 7 The composite yarn obtained in Comparative Example 2 showed that, with the increase in the amount of silver nanowires added, the conductivity and stability of the yarn did not improve, and even decreased to some extent compared with Example 1. This is because if too many silver nanowires are loaded on the yarn surface, the silver nanowires are prone to breakage during stretching, resulting in a reduced detection range and decreased sensitivity.

[0057] See Figure 8 From the perspective of reduction time, Figure (a) shows the resistance change rate and sensitivity of the yarn after 8 hours of reduction. When the reduction time is 8 hours, the tensile sensing detection range of the yarn is 1-40%, which is lower than that of Example 1. This is because the reduction of graphene oxide on the yarn surface is incomplete, and the conductive network on the yarn surface is not stable enough and is easily damaged when stretched. Figure (b) shows the sensitivity of the yarn after 16 hours of reduction. It can be seen that the detection range of the yarn reaches 60%, which is the same as that of Example 1, but its sensitivity is lower because the yarn reduction time is not enough and the three-dimensional conductive network on the yarn surface is not completely stable.

[0058] See Figure 9 From the perspective of yarn pretreatment, it can be seen from the figure that the detection range of the yarn reaches 60%, and the sensitivity factor in the 1-30% deformation range is higher than that of Example 1. However, as the stretching range increases, the sensitivity of the yarn in Comparative Example 4 remains unchanged, which is significantly different from that of Example 1. It can be seen that when plasma treatment is lacking, the composite yarn is limited in detecting the stretching range.

[0059] See Figure 10When the number of impregnation and drying cycles was 5, the weight gain percentage of the conductive yarn was 9%, and the resistance of the conductive yarn was higher than that in Example 1. The conductive material load was insufficient, resulting in a larger resistance, a smaller tensile sensing range (0-40%), and a poorer sensing effect. The GF was 2202.5, indicating that the conductivity was affected by the thickness of the conductive layer. However, when the number of impregnation and drying cycles was 15, the weight gain percentage of the conductive yarn reached 22%, the improvement in the conductivity of the yarn became smaller, and the surface conductive material was prone to falling off, leading to unstable resistance. The GF was 2294.97, indicating that the thickness of the conductive layer was no longer the main factor limiting the conductivity of the conductive yarn at this time.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a composite sensing yarn with high sensitivity, comprising the following steps: Step 1, Pretreatment of flexible substrate: Polyurethane yarn is immersed in an organic solvent to remove impurities from the surface of the polyurethane yarn, and then subjected to plasma treatment. Step 2, Preparation of conductive solution: Add graphene oxide powder to deionized water and disperse it by ultrasonication. Adjust the pH of the graphene oxide dispersion with ammonia water to obtain a graphene oxide dispersion. Take the silver nanowire dispersion prepared by the polyol method and mix it with the graphene oxide dispersion to obtain a silver nanowire / graphene oxide mixed conductive solution. Step 3, Preparation of composite sensing yarn: The pretreated polyurethane yarn in step 1 is immersed in the silver nanowire / graphene oxide mixed conductive solution in step 2, then taken out and dried to obtain polyurethane yarn treated with conductive liquid. Step 4, Reduction of graphene oxide: The polyurethane yarn treated with conductive liquid in step 3 is placed in vitamin C solution, heated to react, and dried to obtain composite sensing yarn.

2. The method for preparing composite sensing yarn with high sensitivity as described in claim 1, characterized in that, In step 1, the organic solvent is ethanol or acetone; the treatment time with the organic solvent is 10-60 min; preferably 20-40 min. In step 1, the polyurethane yarn is immersed in the organic solvent and impurities are removed using ultrasonic assistance; the ultrasonic removal time is 20-40 minutes.

3. The method for preparing the composite sensing yarn with high sensitivity factor as described in claim 2, characterized in that, In step 1, after removing impurities from the surface of the polyurethane yarn, it is dried to keep the polyurethane yarn dry; the drying temperature is 70-90℃. In step 1, after removing impurities from the surface of the polyurethane yarn, plasma treatment is performed; the plasma treatment time is 2-15 min; preferably 3-10 min.

4. The method for preparing a composite sensing yarn with a high sensitivity factor as described in claim 1, characterized in that, In step 2, the graphene oxide powder is added to deionized water and ultrasonically dispersed, and the concentration of the graphene oxide is 0.1%-2% by mass and volume; the pH of the graphene oxide dispersion is adjusted to 6-8 using ammonia.

5. The method for preparing the composite sensing yarn with high sensitivity factor as described in claim 4, characterized in that, In step 2, the silver nanowire dispersion prepared by the polyol method is mixed with the graphene oxide dispersion, and the volume ratio of the amount of silver nanowire dispersion to the volume ratio of the graphene oxide dispersion is (4-6):

5. The silver nanowire dispersion and the graphene oxide dispersion are mixed using ultrasonic dispersion assistance, and the ultrasonic dispersion time is 10-60 min.

6. The method for preparing the composite sensing yarn with high sensitivity factor as described in claim 1, characterized in that, In step 3, the polyurethane yarn treated with conductive liquid is repeatedly impregnated to increase its weight by 14%-16% compared to the untreated polyurethane yarn in step (1).

7. The method for preparing the composite sensing yarn with high sensitivity factor as described in claim 1, characterized in that, In step 4, the concentration of the vitamin C solution is 8-20 mg / mL.

8. The method for preparing a composite sensing yarn with a high sensitivity factor as described in claim 1, characterized in that, In step 4, the temperature of the heating reaction is 85-100℃.

9. The method for preparing the composite sensing yarn with high sensitivity factor according to any one of claims 7-8, characterized in that, In step 4, the heating reaction time is no less than 20 hours.

10. A composite sensing yarn with a high sensitivity factor, prepared according to the preparation method of any one of claims 1-9.

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