Temperature interference resistant strain sensing composite yarn and preparation method and application thereof

Abstract

The present application relates to a strain sensing composite yarn resistant to temperature interference and a preparation method and application thereof, and belongs to the technical field of intelligent textiles. The preparation method comprises the following steps: S1, uniformly attaching a conductive solution on temperature-insensitive fibers by means of immersion drying to obtain composite fibers; the conductive solution is composed of carbon nanotubes, metal nanowires and water; S2, wrapping the composite fibers on the surface of elastic yarn by means of ring spinning to obtain composite elastic yarn; the elastic yarn is kept in a stretched state during the wrapping process; S3, coating flame-retardant fibers on the surface of the composite elastic yarn by means of friction spinning to obtain the strain sensing composite yarn resistant to temperature interference; the composite elastic yarn is kept in a stretched state during the coating process, and the strain sensing composite yarn resistant to temperature interference with different structures has great application potential in the fields of wearable flexible electronic devices, motion and health detection, human-computer interaction and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of intelligent textiles, and particularly relates to a strain sensing composite yarn resistant to temperature interference and a preparation method and application thereof. BACKGROUND

[0002] With the development of current technology, electronic devices have developed in the direction of softness, extensibility, free bending and folding, and wearability, especially for human health monitoring and human-computer interaction. Compared with traditional rigid strain sensors, textile (fiber, yarn, fabric) based devices can work under conditions of stretching, bending and twisting, and can better fit the human body. By using traditional textile processing technologies (such as spinning, weaving, knitting, and weaving), conductive materials can be easily integrated into intelligent textiles, and the structure and form of the yarn or fabric can be adjusted to achieve the desired performance, while retaining the good air permeability, flexibility and comfort of traditional textiles, facilitating wear.

[0003] From the sensing mechanism, textile-based flexible strain sensors can be divided into resistance type, capacitance type, piezoelectric type, etc. The most common and widely used is the resistance type strain sensor. Although the resistance type strain sensor has the characteristics of simple structure, easy preparation and easy collection of electrical signals, it is easily affected by the environment temperature in the actual application process. The electrical signal inevitably fluctuates under the change of external temperature, greatly reducing the accuracy of the sensor.

[0004] Chinese patent CN 113846399A discloses a high-sensitivity strain sensing composite yarn and its preparation method and application. The strain sensing composite yarn uses the dipping method to prepare wool / carbon nanotubes, and then uses friction spinning technology to coat the wool / carbon nanotubes on the surface of spandex filaments to obtain a strain sensing composite yarn. This yarn-based strain sensing composite yarn has the characteristics of high sensitivity and good flexibility, but does not consider that the resistance type sensor prepared by using single carbon nanotube material as conductive material is easily affected by temperature. When used in an environment with temperature changes for a long time, the accuracy of the sensor will be greatly affected. Chinese patent CN 113790741A discloses a multifunctional sensing integrated flexible fabric-based sensor and its application, which uses the composite of positive and negative temperature coefficient conductive materials to realize the temperature interference resistance of the overall material, but does not consider the influence of the thermal expansion coefficient of the base material, resulting in not widely applicable.

[0005] In view of this, it is necessary to develop a flexible resistance type strain sensor that is comfortable to wear, has good sensing performance, and is resistant to temperature interference to solve the above problems. SUMMARY

[0006] To solve the above technical problems, the application provides a strain sensing composite yarn resistant to temperature interference and a preparation method and application thereof.

[0007] A first object of the application is to provide a preparation method of a strain sensing composite yarn resistant to temperature interference, comprising the following steps,

[0008] S1, uniformly attaching a conductive solution on temperature-insensitive fibers by means of immersion drying to obtain composite fibers; the conductive solution is composed of carbon nanotubes, metal nanowires and water;

[0009] S2, wrapping the composite fibers in S1 around the surface of elastic yarn by means of ring spinning to obtain composite elastic yarn; the elastic yarn is kept in a stretched state during the wrapping process;

[0010] S3, coating the composite elastic yarn in S2 with flame-retardant fibers by means of friction spinning to obtain the strain sensing composite yarn resistant to temperature interference; the composite elastic yarn is kept in a stretched state during the coating process.

[0011] In an embodiment of the application, in S1, the metal nanowires are selected from one or more of silver nanowires, gold nanowires and copper nanowires; the absolute value of the linear expansion coefficient of the temperature-insensitive fibers is less than 9*10 -6 1 / K, and when the linear expansion coefficient of the temperature-insensitive fibers is negative, the amount of metal nanowires is increased.

[0012] Further, in S1, the diameter of the metal nanowires is 30-60 nm, and the length is 2-10 microns.

[0013] In an embodiment of the application, in S1, the mass ratio of carbon nanotubes to metal nanowires in the conductive solution is 1:4-6; the concentration of metal nanowires is 10-20 mg / mL. The conductive fibers composed of metal nanowires and temperature-insensitive fibers as a whole exhibit positive temperature resistance coefficient properties, that is, the resistance increases with the increase of temperature, while the conductive fibers composed of carbon nanotubes and temperature-insensitive fibers as a whole exhibit negative temperature resistance coefficient properties, that is, the resistance decreases with the increase of temperature. By adjusting the mixed mass ratio of silver nanowires and carbon nanotubes, a special composite conductive network is formed on the surface of the temperature-insensitive fibers to obtain composite fibers (carbon nanotubes / metal nanowires / temperature-insensitive fibers).

[0014] In one embodiment of the present application, in S2, the elastic yarn is one or more of spandex, polyester filament and rubber filament.

[0015] In one embodiment of the present application, in S2, during the ring spinning process, the spindle speed is 6000 r / min-8000 r / min, and the yarn twist is (40-70) T / 10 cm. The composite fiber is uniformly coated on the surface of the elastic yarn by using the ring spinning technology to form a core-sheath structure, and a composite elastic yarn (elastic yarn / carbon nanotube / metal nanowire / temperature-insensitive yarn) is obtained.

[0016] In one embodiment of the present application, in S3, the flame-retardant fiber is selected from aramid fiber, polytetrafluoroethylene fiber or polyimide fiber.

[0017] In one embodiment of the present application, in S3, during the friction spinning process, the feeding speed of the flame-retardant fiber is 1.0 m / min-2.0 m / min, the output speed is 4 m / min-7 m / min; the rotating speed of the carding roller is 3000 r / min-4000 r / min, the rotating speed of the friction roller is 600 r / min-1200 r / min, and the winding speed is 5 m / min-8 m / min. A layer of flame-retardant fiber is tightly coated on the outer layer of the composite elastic yarn by using the friction spinning technology, so that the overall resistance of the composite yarn changes less than a preset relative resistance change threshold (less than 3%) with temperature within a certain temperature range, and a strain sensing composite yarn with three-layer structure and temperature interference resistance is obtained.

[0018] In one embodiment of the present application, in S2 and S3, the said maintaining the stretched state is independently stretching the yarn to 110%-150% of the normal state.

[0019] The second object of the present application is to provide a temperature interference resistant strain sensing composite yarn prepared by the said method.

[0020] In one embodiment of the present application, the diameter of the single temperature interference resistant strain sensing composite yarn is 0.4 mm-1.0 mm.

[0021] The third object of the present application is to provide an application of the said temperature interference resistant strain sensing composite yarn in health detection and human-computer interaction.

[0022] The technical solution of the present application has the following advantages compared with the prior art:

[0023] (1) The anti-interference method of the strain sensing composite yarn provided by the application uses metal nanowires and carbon nanotubes as composite conductive materials, and makes them uniformly adhere to temperature-insensitive fibers through immersion, uses the positive temperature resistance of metal nanowires, the negative temperature resistance of carbon nanotubes, and the small thermal expansion coefficient of temperature-insensitive fibers, adjusts the proportion of the use of metal nanowires and carbon nanotubes according to different base yarns, and uses the excellent flame-retardant and heat-insulating performance of flame-retardant fibers, so that the overall temperature resistance coefficient of the material is close to zero, thereby providing a new and effective way to realize the temperature interference resistance of a flexible resistance strain sensor.

[0024] (2) The strain sensing composite yarn provided by the application is not only flexible, and the tensile strain can reach about 100%, but also has a simple preparation process and can be mass-produced. The yarn structure is regulated by combining the proportion selection of two materials with different temperature resistance coefficients and the yarn structure, so that the influence of the external environment temperature on the relative resistance of the sensor is almost zero. Different structures of yarns are prepared by regulating the technical parameters of ring spinning and friction spinning, the sensing performance of the yarns is optimized, the temperature range of temperature interference resistance is improved, the functions of good strain sensing and temperature interference resistance in a high temperature range are realized, and the yarns have great application potential in the fields of wearable flexible electronic devices, motion and health detection, and human-computer interaction.

[0025] (3) The preparation method provided by the application adjusts the twist factor in ring spinning and the speed of the separating comb, rubbing comb, feeding, outputting and curling of a friction spinning machine, so as to obtain strain sensing composite yarns with different structures and properties and temperature interference resistance. The twist factor is a relative value and can be used to represent the twist size of the yarn. The twist factor cannot be too small, otherwise the cohesive force between the short fiber tows and the core yarn filaments is not large enough, the two cannot be effectively wrapped, the core yarn is prone to slip, the covering effect is poor, and the sensing performance is poor. In addition, the twist factor cannot be too large, otherwise the twist back angle of the yarn is too small, the twist shrinkage phenomenon is prone to occur, and the sensing performance and the yarn quality are prone to be affected. The faster the speed of the separating comb of the friction spinning machine is, the more single fibers are fed, and the thicker the flame-retardant fibers wrapped on the surface of the elastic yarn / carbon nanotube / metal nanowire / temperature-insensitive yarn are by using the friction effect. The residence time of the elastic yarn / carbon nanotube / metal nanowire / temperature-insensitive yarn between the two dust cages can be controlled by adjusting the speed of feeding and outputting. The slower the output speed is, the longer the residence time of the elastic yarn / carbon nanotube / metal nanowire / temperature-insensitive yarn between the dust cages is, and the more densely the flame-retardant fibers are wrapped. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to make the content of the application easier to be clearly understood, the application will be further described in detail below according to specific embodiments of the application and in combination with the drawings, in which:

[0027] Figure 1 Schematic diagram of the device for preparing the strain sensing composite yarn with temperature interference resistance of the application;

[0028] Figure 2 Optical micrograph of the strain sensing composite yarn with temperature interference resistance of the application;

[0029] Figure 3 Electron micrograph of the surface of the carbon nanotube / silver nanowire / cotton fiber of the application;

[0030] Figure 4 Relative resistance change graph of the spandex / carbon nanotube / silver nanowire / cotton yarn with temperature rising under different composite ratios of silver nanowire and carbon nanotube of the application, wherein the left graph is the relative resistance change when the temperature rises from room temperature to 120℃, and the right graph is the relative resistance change when the temperature rises from room temperature to 60℃;

[0031] Figure 5 Relative resistance change graph of the strain sensing composite yarn with temperature interference resistance of the application with different twist degrees when stretched to 20% of the original length;

[0032] Figure 6 Relative resistance change graph of the strain sensing composite yarn with temperature interference resistance of the application with different diameters obtained by coating aramid fibers with different thicknesses;

[0033] Figure 7 Electrical signal response curve graph of the strain sensing composite yarn with temperature interference resistance of the application for detecting different angles of elbow bending under different temperature conditions, wherein the left graph is the electrical signal response curve graph for detecting different angles of elbow bending under 100℃, and the right graph is the electrical signal response curve graph for detecting different angles of elbow bending under room temperature (25℃);

[0034] Marked for reference: 1-spandex filament, 2-tension clamp, 3-guide roller, 4-front roller, 5-carbon nanotube / silver nanowire / cotton fiber, 6-guide hook, 7-aramid fiber, 8-splitting roller, 9-dust cage, 10-strain sensing composite yarn with temperature interference resistance, DETAILED DESCRIPTION

[0035] The application will be further described in conjunction with the drawings and specific embodiments so that those skilled in the art can better understand the application and implement it, but the embodiments are not limiting to the application.

[0036] In the application, unless otherwise specified, the diameter of the silver nanowire used in the embodiments is 30nm-60nm, and the length is 2μm-10μm.

[0037] Embodiment 1

[0038] Reference Figure 1The strain sensing composite yarn against temperature interference and the preparation method thereof are specifically shown and include the following steps:

[0039] S1, preparation of conductive solution: silver nanowires and single-walled carbon nanotubes are respectively dissolved in water according to different mass ratios (1:4, 1:5, 1:6) to obtain conductive solutions with different composite ratios, and the concentration of silver nanowires in the conductive solution is 10 mg / mL.

[0040] S2, preparation of composite fiber: the cotton fiber is immersed in the conductive solution for 25 min, taken out, and dried in an oven with a temperature of 45°C, and the process is repeated for 5 times to obtain (carbon nanotube / silver nanowire / cotton fiber).

[0041] S3, preparation of composite elastic yarn: the spandex filament 1 is wound around the core yarn tensioner, stretched through the tension clamp 2, guided by the guide roller 3, fed from the front roller 4 pressure roller, converged with the carbon nanotube / silver nanowire / cotton fiber 5, and simultaneously enters the twisting zone. The spandex filament is wrapped in the carbon nanotube / silver nanowire / cotton fiber, and the yarn is twisted and wound through the guide hook 6 under the joint action of the ring, the ring traveler and the spindle. After twisting, the sheath carbon nanotube / silver nanowire / cotton fiber is tightly wrapped outside the core spandex filament. The core yarn shrinks to form a yarn cover after leaving the front roller due to the removal of external force, and the composite elastic yarn (spandex / carbon nanotube / silver nanowire / cotton yarn) is obtained.

[0042] In the ring spinning process, the spindle speed is 8000 r / min, the yarn twist is 60T / 10cm, and the yarn is stretched to 120% of the normal state.

[0043] S3, preparation of strain sensing composite yarn against temperature interference: several aramid fibers 7 are fed into the single fiber through the drafting device and the carding roller 8, and the fibers pass through the wedge-shaped area of the dust cage 9 in a floating state under the action of the carding roller 8 and the dust cage 9. The spandex / carbon nanotube / silver nanowire / cotton yarn is unwound from the bobbin and fed between the two same direction rotating dust cages 9. The two dust cages rotate towards each other, so that the aramid fiber tows in them not only receive an upward friction force, but also receive a downward friction force. After the aramid fiber tows are carded by the carding roller, they fall on the spandex / carbon nanotube / silver nanowire / cotton yarn and are wrapped outside the spandex / carbon nanotube / silver nanowire / cotton yarn under the action of the dust cage, to form the strain sensing composite yarn 10 against temperature interference with the spandex / carbon nanotube / silver nanowire / cotton yarn as the core and the aramid fiber as the sheath, which is wound on the friction spinning bobbin.

[0044] In the friction spinning process, the friction spinning machine model is HFX-02, and the parameters are set as follows: the rotating speed of the combing roller is 3500 r / m, the rotating speed of the friction roller is 1000 r / m; the feeding speed of the aramid fiber is 1.2 m / min, the output speed is 5.8 m / min, and the winding speed is 6.2 m / min, and the yarn is stretched to 120% of the normal state.

[0045] Test Example 1

[0046] The temperature interference resistant strain sensing composite yarn prepared in Example 1 (the mass ratio of carbon nanotubes to silver nanowires is 1:5) is characterized by a 3D microscope, and the results are shown in Figure 2 From Figure 2 it can be seen that the temperature interference resistant strain sensing composite yarn has a three-layer structure, the innermost layer is a spandex filament, which makes the yarn have excellent tensile properties; the middle layer is a cotton fiber containing carbon nanotubes and silver nanowires, which makes the yarn have excellent sensing performance; the outermost layer is aramid fiber, which makes the yarn have certain strength, heat insulation and flame retardant properties. In addition, the aramid fiber can also prevent the shedding of the inner layer carbon nanotubes and silver nanowires.

[0047] Test Example 2

[0048] Based on Example 1, the carbon nanotubes / silver nanowires / cotton fiber (the mass ratio of carbon nanotubes to silver nanowires is 1:5) is characterized by an electron microscope (10000 times), and the results are shown in Figure 3 From Figure 3 it can be seen that through five times of immersion-drying cycles, the silver nanowires and carbon nanotubes have been uniformly attached to the cotton fiber, and are connected to each other to establish a conductive network.

[0049] Test Example 3

[0050] Based on Example 1, the spandex / carbon nanotube / silver nanowire / cotton yarn is fixed on a heating table, and the two ends are linked to a Keithley-DMM 7510 instrument for resistance measurement, and the trend of resistance change in the temperature range of 25-120℃ is measured, and the results are shown in Figure 4 From Figure 4 it can be seen that the spandex / carbon nanotube / silver nanowire / cotton yarn prepared when the mass ratio of carbon nanotubes to silver nanowires is 1:5 has an absolute value of relative resistance change less than 3% in the temperature range of 25-60℃, and the temperature coefficient of resistance is close to zero.

[0051] Test Example 4

[0052] Based on Example 1 (carbon nanotube to silver nanowire mass ratio of 1:5), temperature-sensitive strain-sensing composite yarns with different twists (40T / 10cm, 50T / 10cm, 60T / 10cm, 70T / 10cm) were stretched using a general testing system (EUT 2203, gauge length 30mm, strain rate 150mm / min). The stretching length was 20% of the yarn sensor length. The resistance at both ends of the yarn sensor was measured using a Keithley-DMM 7510. The results are as follows. Figure 5 As shown. From Figure 5 It can be seen that the increased twist of the spandex / carbon nanotube / silver nanowire / cotton yarn produced by ring spinning results in a tighter outer layer of cotton fibers. This leads to increased changes in the conductive pathway during stretching, thereby improving sensing performance. However, if the twist is too high, the short fibers become too tightly packed, and the large interaction forces make it difficult to separate them during stretching, thus reducing sensing performance. When the twist of the spandex / carbon nanotube / silver nanowire / cotton yarn is 60T / cm, the tightness of the cotton fibers covering the spandex filament is appropriate, resulting in good sensing performance.

[0053] Test Example 5

[0054] Based on Example 1 (carbon nanotube to silver nanowire mass ratio of 1:5), by controlling the output and input speeds of the triboelectric spinning machine, five composite outer diameters of temperature-sensitive strain sensors with different coating diameters were obtained: 0.3mm×0.4mm, 0.3mm×0.6mm, 0.3mm×0.8mm, and 0.4mm×1.0mm, respectively named SCAVA-D0.4, SCAVA-D0.6, SCAVA-D0.8, and SCAVA-D1.0. Referring to the above experiments, the effect of coating aramid fibers of different thicknesses on their performance was investigated, and the results are as follows... Figure 6 As shown. From Figure 6 It can be seen that as the thickness of the aramid coating on the outside of the temperature-resistant strain-sensing composite yarn increases, the aramid fiber coating becomes denser, thus increasing the coating rate. The densely distributed, fluffy flame-retardant fibers hinder air convection, significantly reducing heat conduction and limiting heat convection. In addition, the layered and irregularly twisted fibers also increase radiation reflection, thus improving the temperature resistance range of this three-layer core-sheath structure yarn and giving it excellent flame retardancy.

[0055] Test Example 6

[0056] The temperature interference resistant strain sensing composite yarn of Example 1 (mass ratio of carbon nanotubes to silver nanowires is 1:5) was used to carry out wearable application test. In order to demonstrate the wearable application of the temperature interference resistant strain sensing yarn, the temperature interference resistant strain sensing composite yarn was sewn on the fabric at the elbow joint of the human body, the yarn was connected with the resistance detection device by using the wire, and the response of the electrical signal at different angles of the elbow bending was monitored at normal temperature (25℃) and high temperature (100℃) by using wireless transmission technology, and the results are shown in Figure 7 Figure 7 It can be seen that at normal temperature and at high temperature, with the increase of the bending angle of the elbow, the relative resistance change increases, when the elbow returns to the original angle, the relative resistance change also returns to the initial value, the change of the curve remains the same as the frequency of the elbow movement, and the electrical signal curve at high temperature is almost the same as that at normal temperature, which shows that the temperature interference resistance performance is good.

[0057] Obviously, the above examples are only examples for clearly illustrating, and are not limited to the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. All the embodiments do not need to be exhausted here. The obvious changes or variations derived therefrom are still within the protection scope of the present application.​

Claims

1. A method of making a strain sensing composite yarn that is resistant to temperature interference, characterized by, It comprises the following steps, S1, uniformly attaching an electrically conductive solution on temperature-insensitive fibers by means of dry impregnation, to obtain composite fibers; the electrically conductive solution is composed of carbon nanotubes, metal nanowires and water; the mass ratio of carbon nanotubes and metal nanowires in the electrically conductive solution is 1:4-6; the concentration of metal nanowires is 10mg / mL-20mg / mL; S2, wrapping the composite fibers of S1 around the surface of elastic yarn by means of ring spinning, to obtain composite elastic yarn; the elastic yarn is kept in a stretched state during the wrapping process; S3, coating the composite elastic yarn of S2 with flame-retardant fibers by means of friction spinning, to obtain the temperature-interference-resistant strain sensing composite yarn; the composite elastic yarn is kept in a stretched state during the coating process; during the friction spinning process, the feeding rate of the flame-retardant fibers is 1.0m / min-2.0m / min, the output rate is 4m / min-7m / min; the rotating speed of the carding roller is 3000r / min-4000r / min, the rotating speed of the friction roller is 600r / min-1200r / min, and the winding speed is 5m / min-8m / min; In S2 and S3, the stretched state is independently stretched to 110%-150% of the normal state.

2. The method of claim 1, wherein the temperature-independent strain sensing composite yarn is prepared by the steps of: In S1, the metal nanowires are selected from one or more of silver nanowires, gold nanowires, and copper nanowires; the temperature-insensitive fiber has an absolute value of a linear expansion coefficient less than 9 x 10 -6 1 / K.

3. The method for preparing the temperature-resistant strain-sensing composite yarn according to claim 1, characterized in that, In S2, the elastic yarn is one or more of spandex, polyester filament and rubber filament.

4. The method of claim 1, wherein the temperature-independent strain sensing composite yarn is prepared by the steps of: In S2, during the ring spinning process, the spindle speed is 6000r / min-8000r / min, and the yarn twist is (40-70)T / 10cm.

5. The method for preparing the temperature-resistant strain-sensing composite yarn according to claim 1, characterized in that, In S3, the flame-retardant fibers are selected from aramid fibers, polytetrafluoroethylene fibers or polyimide fibers.

6. The temperature-interference-resistant strain sensing composite yarn prepared by the method of any one of claims 1-5.

7. The temperature-interference-resistant strain sensing composite yarn of claim 6 in the application of health detection and human-computer interaction.

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