Flexible strain sensing composite yarn and its preparation method and application

Abstract

The application discloses a flexible strain sensing composite yarn and a preparation method and application thereof, which is prepared from yarns with a large difference in deformation capacity (elastic force) and conductive capacity as raw materials, and a strain sensing fabric is woven by using a traditional weaving method, so that the preparation process is simple and batch production is facilitated; the winding state of the two kinds of yarns is changed by stretching, so that the electrical properties (resistance) of the fabric woven from the composite yarn are changed, so that the fabric has a strain sensing function; and the original characteristics of the fabric, such as comfort, air permeability and washability, are maximally retained, and seamless integration of the device and the garment can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fabric-based flexible strain sensor, and particularly relates to a flexible strain sensing composite yarn as well as a preparation method and application thereof. BACKGROUND

[0002] A strain sensor reflects the size of the strain stimulus by measuring the change of the electrical property of the material under the deformation of force. There are generally two preparation methods for the resistive fabric strain sensor: (1) directly weaving the conductive yarn into the fabric structure by using the weaving or knitting technology; and (2) impregnating, coating or drawing finishing of the fabric with the conductive component. The former is mostly based on the knitted structure, and the resistance change is generated by the deformation of the loop structure or the change of the sensing component property, so as to realize the strain sensing function. The conductive yarn is generally prepared by silver plating or compounding with other functional materials. The latter is generally prepared by coating a completely continuous conductive coating on the surface of the fabric or impregnating the conductive filler, so as to realize the strain sensing function by forming cracks or changes in the internal conductive network in the sensing layer. Due to the unique loop structure of the knitted fabric, the yarn storage in unit length is more and the fabric has good elasticity, so the base of the fabric-based strain sensor is mainly knitted structure. At present, the visualization function of strain is mostly realized by force-induced color-changing materials, which are a kind of materials capable of producing reversible optical property changes under the action of external force. However, the cost of the force-induced color-changing materials is relatively high, and the synthesis is relatively complex.

[0003] Wang Jinfeng et al. wove weft-knitted fabric with silver-plated chinlon yarn as the raw material as the strain sensing material, and the sensitivity was 2.51 within a strain of 2%, which had a low strain detection range. Yi Weijing et al. coated the conductive composite material on the fabric by printing to prepare a sensitive material with strain sensing function, but the resistance responses in the warp and weft directions were inconsistent, and the stability and washability of the strain sensing fabric could not be guaranteed due to the poor adhesion between the conductive coating and the fabric substrate. The patent with the authorization number CN108680095B provides a flexible strain sensor based on carbon nanofiber yarn fabric, and the preparation method includes coating a polymer film on the upper and lower surfaces of the fabric, which hinders the comfort and air permeability of the fabric. The patent with the publication number CN115164704A provides a wearable fabric strain sensor with a layered structure, which includes a modified fabric and a carbon-based ink conductive film coated on one side of the modified fabric, but the preparation process of the device is relatively complex, and the conductive film is easy to delaminate or fall off on the fabric substrate. Zhao Kai et al. combined photonic crystal elastic materials with weft-knitted polyester fabric and carbonized fabric respectively to develop visual strain sensing materials, but the cost of the photonic crystal is high, and the preparation is difficult, so it is not conducive to the mass production of the device.

[0004] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general context of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art. SUMMARY

[0005] The present application aims to provide a flexible strain sensing composite yarn and its preparation method and application, which uses yarns with large difference in deformation ability (elastic force) and conductivity as raw materials to prepare the composite yarn, uses traditional weaving method to weave the strain sensing fabric, and has simple preparation process, which is conducive to mass production; and the original characteristics of the fabric, such as comfort, air permeability, washability, etc., are retained to the maximum extent, and seamless integration of the device and the garment can be achieved.

[0006] To achieve the above-mentioned purpose, one embodiment of the present application provides a flexible strain sensing composite yarn, comprising:

[0007] a first yarn having a first elastic force;

[0008] a second yarn having a second elastic force;

[0009] one of the first yarn and the second yarn is a conductive yarn, and the other of the first yarn and the second yarn is an insulating yarn;

[0010] wherein the first yarn is wound on the second yarn with the second yarn as the center line, and under the action of force, the second yarn can be counter-wound on the first yarn with the first yarn as the center line;

[0011] or,

[0012] the second yarn is wound on the first yarn with the first yarn as the center line, and under the action of force, the first yarn can be counter-wound on the second yarn with the second yarn as the center line.

[0013] In one or more embodiments of the present application, the first elastic force is smaller than the second elastic force; the first yarn is spirally wound and covers the second yarn with the second yarn as the center line.

[0014] In one or more embodiments of the present application, the flexible strain sensing composite yarn has two states:

[0015] In the first state, the second yarn is in a straightened state, and the first yarn is arranged in a winding manner to completely cover the second yarn;

[0016] In the second state, the first yarn is in a straightened state, and the second yarn is arranged in a winding manner to cover the second yarn;

[0017] The flexible strain sensing composite yarn can be switched from a first state to a second state under stress, and recovered from the second state to the first state under stress removal.

[0018] In one or more embodiments of the present application, the first elastic force is greater than the second elastic force.

[0019] The second yarn is spirally wrapped around the first yarn with the first yarn as a center line.

[0020] In one or more embodiments of the present application, the first yarn is uniformly wrapped on the second yarn; or, the second yarn is uniformly wrapped on the first yarn.

[0021] In one or more embodiments of the present application, the color of the first yarn is different from the color of the second yarn; and / or,

[0022] The shape of the first yarn is different from the shape of the second yarn.

[0023] In one or more embodiments of the present application, the first yarn is selected from a pure metal yarn, a pure carbon material yarn, a silver-plated yarn or a blended yarn, and the second yarn is selected from a spandex core yarn and a textured yarn; or,

[0024] The first yarn is selected from a non-conductive polymer filament or staple yarn, and the second yarn is selected from a conductive polymer filament or staple yarn; or,

[0025] The second yarn is selected from a pure metal yarn, a pure carbon material yarn, a silver-plated yarn or a blended yarn, and the first yarn is selected from a spandex core yarn and a textured yarn; or,

[0026] The second yarn is selected from a non-conductive polymer filament or staple yarn, and the first yarn is selected from a conductive polymer filament or staple yarn.

[0027] A specific embodiment of the present application further provides a preparation method of a flexible strain sensing composite yarn, comprising:

[0028] providing a first yarn, the first yarn having a first elastic force;

[0029] providing a second yarn, the second yarn having a second elastic force, one of the first yarn and the second yarn being a conductive yarn, and the other of the first yarn and the second yarn being an insulating yarn;

[0030] wrapping the first yarn on the second yarn with the second yarn as a center line;

[0031] or,

[0032] The second yarn is wrapped on the first yarn with the first yarn as a center line.

[0033] The flexible strain sensing fabric is knitted by the flexible strain sensing composite yarn.

[0034] In one or more embodiments of the present application, the flexible strain sensing fabric is a woven fabric or a knitted fabric.

[0035] Compared with the prior art, the flexible strain sensing composite yarn of the present application is prepared by winding two kinds of yarns with different and relatively large differences in deformation ability (elastic force) and electrical conductivity, and the winding state of the two kinds of yarns can be changed by stretching, so as to change the electrical properties (resistance) of the fabric knitted by the composite yarn, so that the fabric has a strain sensing function.

[0036] The flexible strain sensing composite yarn of the present application is twisted into a composite yarn by two kinds of yarns with obvious differences in color, shape or appearance, and the visual function of strain can be realized by changing the winding state of the two kinds of yarns by stretching. In addition, since the force-induced color-changing material is not involved in the preparation process, the cost of the strain sensing composite yarn and the strain sensing fabric is reduced, which is conducive to mass production.

[0037] The flexible strain sensing composite yarn of the present application is prepared by using yarns with large twist and strong stretching ability, and the strain sensing fabric is knitted by using the yarns, so that a large strain detection range can be obtained, and the flexible strain sensing fabric is suitable for large strain application scenarios.

[0038] The flexible strain sensing fabric of the present application is knitted by using the flexible strain sensing composite yarn through a traditional weaving method, and the preparation process is simple, which is conducive to mass production. The visual strain sensor is prepared by using all yarns and all fabrics, the original characteristics of the fabric such as comfort, air permeability and washability are maximally retained, and seamless integration of the device and the garment can be realized.

[0039] The flexible strain sensing fabric of the present application is prepared by using yarns which are easy to obtain, and the weaving process of the sensing fabric is simple and short, so that the flexible strain sensing fabric is suitable for mass production. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0041] Figure 1Figure 1 is a structural diagram of a flexible strain sensing composite yarn in an embodiment of the present application, wherein (a) is before being stretched under force, and (b) is after being stretched under force.

[0042] Figure 2 Figure 2 is a fabric machine diagram of a flexible strain sensing fabric in an embodiment of the present application.

[0043] Figure 3 Figure 3 is a structural diagram of an interlacing point in a flexible strain sensing fabric in an embodiment of the present application, wherein (a) is before being stretched under force, and (b) is after being stretched under force. DETAILED DESCRIPTION

[0044] In order to make the person skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0045] As described in the background, a strain sensor reflects the size of a strain stimulus by measuring the change in the electrical property of a material under force deformation. There are generally two preparation methods for a resistive fabric strain sensor: (1) using weaving or knitting technology to directly weave conductive yarn into the fabric structure; and (2) impregnating, coating or drawing finishing of the fabric with a conductive component. The former is mostly based on a knitted structure, and the strain sensing function is realized by the deformation of the loop structure or the change in the property of the sensing component, wherein the conductive yarn is generally prepared by silver plating or compounding with other functional materials. The latter generally prepares a strain sensing fabric by coating a completely continuous conductive coating on the surface of the fabric or impregnating a conductive filler, and realizes the strain sensing function by forming cracks or changes in the internal conductive network in the sensing layer. Due to the unique loop structure of the knitted fabric, the yarn storage in unit length is more and the fabric has good elasticity, and the substrate of the fabric-based strain sensor is mainly knitted structure.

[0046] The first method for preparing a strain sensing fabric is to weave conductive yarn into the fabric by using weaving or knitting technology, to obtain the change in the resistance of the material by the deformation of the fabric structure during stretching, and to realize the strain sensing function. Due to the loose and easy-to-deform characteristics of the knitted structure, the currently more studied fabric substrate is a knitted fabric. However, the deformation capacity of the knitted fabric is limited, and therefore the detectable strain range is often not high.

[0047] The second type of strain-sensing fabric material mostly combines traditional fabrics with electrically sensitive materials through methods such as impregnation, coating, and lifting. However, the weak interaction between the two can cause the conductive components to easily detach during use, weakening the sensing performance of the device. In addition, the electrically sensitive material can also affect the original comfort, breathability, and washability of the fabric to some extent.

[0048] Visual strain sensing materials based on fabrics typically achieve visualization by combining mechanochromic materials with the fabric matrix. However, mechanochromic materials are expensive and require additional synthesis, which hinders the mass production and application of visual strain sensing fabrics.

[0049] Based on this, this application provides a flexible strain-sensing composite yarn, its preparation method, and its application. The composite yarn is prepared using two yarns with significantly different deformation capabilities (elastic force) and conductivity. The strain-sensing fabric is woven using traditional weaving methods, resulting in a simple preparation process that facilitates mass production. By stretching and changing the winding state of the two yarns, the electrical properties (resistance) of the fabric woven from the composite yarn are altered, enabling it to possess strain-sensing functionality. Furthermore, the original characteristics of the fabric—comfort, breathability, and washability—are preserved to the greatest extent possible, allowing for seamless integration of the device with clothing.

[0050] like Figure 1 As shown, the flexible strain-sensing composite yarn in one embodiment of the present invention includes a first yarn 10 and a second yarn 20. The first yarn 10 has a first elastic force. The second yarn 20 has a second elastic force. One of the first yarn 10 and the second yarn 20 is a conductive yarn, and the other of the first yarn 10 and the second yarn 20 is an insulating yarn. The first yarn 10 is wound around the second yarn 20 with the second yarn 20 as the center line, and after the composite yarn is stretched, the second yarn 20 can be unwound around the first yarn 10 with the first yarn 10 as the center line; or, the second yarn 20 is wound around the first yarn 10 with the first yarn 10 as the center line, and after the composite yarn is stretched, the first yarn 10 can be unwound around the second yarn 20 with the second yarn 20 as the center line.

[0051] In a preferred embodiment, the yarn with greater elasticity in the first yarn 10 and the second yarn 20 serves as the center line, while the yarn with less elasticity is spirally wound and wraps around the yarn with greater elasticity. The two yarns are wrapped together to form a functional composite yarn for weaving a visual strain sensing fabric.

[0052] For example, the first elastic force of the first yarn 10 is less than or much less than the second elastic force of the second yarn 20. Here, the relatively small elastic force is defined as low elasticity, and the relatively large elastic force is defined as high elasticity, so the first yarn 10 is a low-elasticity yarn, and the second yarn 20 is a high-elasticity yarn. The first yarn 10 is spirally wound around the second yarn 20 as a center line.

[0053] In the initial state, the second yarn 20 in the straightened state is completely wrapped inside by the first yarn 10 in a wound manner. Once stretched by force, the high-elasticity second yarn 20 slowly elongates, and the low-elasticity first yarn 10 slowly straightens and gradually untwists on the surface of the second yarn 20 under the stretching action. Since the first elastic force of the first yarn 10 is small, the deformable amount is small, and the first yarn 10 will be completely straightened under the continuous stretching action. Since the second elastic force of the second yarn 20 is large, the deformable amount is large, and the second yarn 20 will continuously elongate during the stretching process and gradually “counter-wind” on the first yarn 10. Thus, the electrical property (resistance) of the fabric woven from the composite yarn changes, and the fabric has a strain sensing function. The specific principle is as follows:

[0054] When not stretched, the outer layer of the composite yarn is the first yarn 10, and the resistance of the interlacing points of the yarns in the fabric (the interlacing points of the warp and weft composite yarns) is mainly the contact resistance of the raw material of the first yarn 10. When stretched, the second yarn 20 gradually counter-winds on the surface of the first yarn 10, so that a part of the interlacing points of the yarns is the contact resistance of the raw material of the second yarn 20. When continuously stretched, the second yarn 20 completely counter-winds on the surface of the first yarn 10, and the resistance of the interlacing points of the yarns is completely determined by the second yarn 20. Therefore, during the stretching process, the resistance of the fabric gradually changes due to the difference in electrical conductivity between the first yarn 10 and the second yarn 20, and thus the strain sensing principle is obtained.

[0055] In an embodiment, the first yarn 10 is a low-elasticity conductive yarn, which can be selected from pure metal yarns (stainless steel filament yarn, stainless steel staple yarn), pure carbon material yarns (carbon fiber filament, carbon fiber staple yarn, carbonized polymer yarn), silver-plated yarns, or blended yarns (blended with other components). The second yarn 20 is a high-elasticity insulating yarn, which can be selected from spandex core-spun yarns, textured yarns (high-elasticity textured yarn, low-elasticity textured yarn, air-textured yarn, network yarn, stretch yarn, bulk yarn, etc.). Among them, the definition of textured yarn is that the chemical fiber filament is processed by heat and mechanical action to have appearance characteristics such as crimping, spiraling, and looping, and to have stretchability and bulkiness. As the strain increases, the resistance of the sensing fabric woven from the composite yarn gradually increases.

[0056] In one embodiment, the first yarn 10 is a low-elasticity insulating yarn, which can be selected from non-conductive polymer filament or staple yarn (polyester, nylon, polypropylene, chlorofiber, aramid, etc.). The second yarn 20 is a high-elasticity conductive yarn, which can be selected from conductive polymer filament or staple yarn (poly pyrrole, PEDOT:PSS, etc.). As the strain increases, the resistance of the sensing fabric woven from the composite yarn gradually decreases.

[0057] In one embodiment, the second yarn 20 is a low-elasticity conductive yarn, which can be selected from pure metal yarn (stainless steel filament yarn, stainless steel staple yarn), pure carbon material yarn (carbon fiber filament, carbon fiber staple yarn, carbonized polymer yarn), silver-plated yarn or blended yarn (blended with other components). The first yarn 10 is a high-elasticity insulating yarn, which can be selected from spandex core-spun yarn, textured yarn (high-elasticity textured yarn, low-elasticity textured yarn, air-textured yarn, network yarn, stretch yarn, bulked yarn, etc.). The definition of textured yarn is that the chemical fiber filament is subjected to deformation processing under the action of heat and mechanics to have appearance characteristics such as crimping, spiraling, and looping, thereby exhibiting stretchability and bulkiness.

[0058] In another embodiment, the second yarn 20 is a low-elasticity insulating yarn, which is selected from non-conductive polymer filament or staple yarn (polyester, nylon, polypropylene, chlorofiber, aramid, etc.). The first yarn 10 is a high-elasticity conductive yarn, which can be selected from conductive polymer filament or staple yarn (poly pyrrole, PEDOT:PSS, etc.).

[0059] In another embodiment, the first yarn 10 and the second yarn 20 are different in color or shape or appearance, and preferably have a significant difference, so that the visualization function of the strain can be achieved. As the stretching proceeds, the color of the composite yarn gradually transitions from the color of the first yarn 10 to the mixed color of the first yarn 10 and the second yarn 20, and then to the color of the second yarn 20. If the strain amount of the sensing fabric is calibrated in advance in correspondence with the color of the fabric, the visual perception of the strain stimulus by the naked eye of the human body can be achieved.

[0060] Reference Figure 1 As shown in (a) of FIG. 1, before the composite yarn is stretched, the first yarn 10 is uniformly wrapped around the surface of the second yarn 20, and the second yarn 20 is in a natural straight state, and neither the first yarn 10 nor the second yarn 20 is subjected to stress.

[0061] Reference Figure 1 As shown in (b) of FIG. 1, under complete stretching, the first yarn 10 changes from the winding state to the completely straightened state and cannot continue to be elongated due to its low elasticity, and the second yarn 20 is stretched and elongated and is “wrapped around” the surface of the straightened first yarn 10 due to the stress. In this way, the outer structure of the composite yarn transitions from the first yarn 10 to the second yarn 20, and the electrical property is also changed accordingly.

[0062] An embodiment of this application also provides a method for preparing the above-mentioned flexible strain sensing yarn, including:

[0063] A first yarn is provided, the first yarn having a first elastic force;

[0064] A second yarn is provided, the second yarn having a second elastic force, one of the first yarn and the second yarn being a conductive yarn, and the other of the first yarn and the second yarn being an insulating yarn;

[0065] Using the second yarn as the center line, wrap the first yarn around the second yarn;

[0066] or,

[0067] Using the first yarn as the center line, wrap the second yarn around the first yarn.

[0068] One embodiment of this application also provides a flexible strain sensing fabric, which is woven from the above-mentioned flexible strain sensing composite yarn.

[0069] The following uses the simplest plain weave fabric as an example to illustrate the weaving process of strain-sensing fabric.

[0070] First, prepare the yarn:

[0071] Two yarns with different properties are wrapped together, so that the first yarn is evenly wound around the second yarn to obtain a composite yarn.

[0072] The composite yarn is steamed to eliminate pre-stress.

[0073] Secondly, weaving is carried out:

[0074] Both warp and weft yarns use the same type of composite yarn, and the warp yarns are arranged according to... Figure 2 (a) and Figure 2 (b) shows the threading diagram and reed threading diagram, which are sequentially threaded into the heddle wires and reed teeth of the corresponding heddle frames on the loom. Among them, The warp yarn indicating this position passes through the corresponding heddle wire and reed tooth;

[0075] On the loom display screen, according to Figure 2 (d) shows the pattern diagram for setting the order of heddling;

[0076] According to the order of latitude (the order of latitude is defined as follows) Figure 2 (c) The weft yarns marked in the weft diagram are introduced sequentially from bottom to top. The weft yarns are introduced each time the heald frame opens.

[0077] The five major movements—opening, weft insertion, beating, curling, and warp feeding—are performed sequentially to gradually weave a continuous fabric.

[0078] After the fabric is removed from the machine, it is left in a natural environment for a period of time to eliminate prestress.

[0079] Referring to (a) in FIG. 3, Figure 3 Referring to (b) in FIG. 3, in the stretched state, the first yarn 10 is wrapped inside the composite yarn, and the second yarn 20 becomes the surface layer of the composite yarn. At this time, the contact resistance of the second yarn 20 dominates the overall resistance of the sensing fabric, so the resistance of the sensing fabric changes, and the amount of change is mainly determined by the difference in electrical conductivity between the first yarn 10 and the second yarn 20.

[0080] Due to the large tensile strain sensing capability of the strain sensing fabric, it can be applied to the detection of large amplitude human joint movement (fingers, wrists, knees). The fabric has good flexibility, biocompatibility and comfort, so it can be attached to the human skin for a long time. Further, the strain sensing fabric can be combined with a tight-fitting garment to monitor human physiological and motion signals in real time. Since the sensing fabric has strain visualization function, it can convert invisible stress into optical signals (color change or shape change) recognizable by the human eye, and thus can be applied to human-computer intelligent interaction field.

[0081] It can be understood that all woven fabrics and knitted fabrics (such as plain weave fabrics, twill weave fabrics, satin weave fabrics, and change weave fabrics, union weave fabrics, complex weave fabrics, etc.) made of the flexible strain sensing composite yarn of the present application and having warp and weft yarn interlacing points in the structure can be used as the fabric structure of the present application and should be within the protection scope of the present application.

[0082] Compared with the prior art, the flexible strain sensing composite yarn of the present application is prepared by winding two kinds of yarns with different and relatively large differences in deformation capability (elastic force) and electrical conductivity. By changing the structure of the composite yarn and the fabric under the action of tension, i.e. changing the winding state of the two kinds of yarns, the electrical properties (resistance) of the fabric woven from the composite yarn can be changed to realize the strain sensing function without additional functional materials, which not only saves cost but also shortens the process flow.

[0083] The flexible strain sensing composite yarn of the present application twists two kinds of yarns with obvious differences in appearance such as color or shape into a composite yarn. By changing the winding state of the two kinds of yarns through stretching, the strain visualization function can be realized, which is simple and easy to operate without complex processing technology or post-processing process. In addition, since no force-induced color-changing material is involved in the preparation process, the cost of the strain sensing composite yarn and the strain sensing fabric is reduced, which is conducive to mass production.

[0084] The flexible strain sensing composite yarn of the present application is prepared by using yarns with large twist and strong tensile capacity (high elasticity), and the strain sensing fabric is woven by using the yarns, so that the maximum tensile deformation of the strain sensing fabric is large, a large strain detection range can be obtained, and the strain sensing fabric is suitable for large strain application scenarios.

[0085] The flexible strain sensing fabric of the present application is woven by using the flexible strain sensing composite yarn through a traditional weaving method, the preparation process is simple, and the fabric is suitable for mass production.

[0086] The flexible strain sensing fabric of the present application is woven by using the flexible strain sensing composite yarn through a traditional weaving method, the preparation process is simple, and the fabric is suitable for mass production.

[0087] The flexible strain sensing fabric of the present application is woven by using the flexible strain sensing composite yarn through a traditional weaving method, the preparation process is simple, and the fabric is suitable for mass production.

[0088] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present application should be defined by the appended claims rather than the above description, and it is intended to include all changes falling within the meaning and range of equivalents of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

[0089] Furthermore, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A flexible strain-sensing composite yarn, characterized in that, include: The first yarn has the first elastic force; The second yarn has a second elastic force; One of the first yarn and the second yarn is a conductive yarn, and the other of the first yarn and the second yarn is an insulating yarn; In this process, with the second yarn as the center line, the first yarn is wound around the second yarn, and under the action of force, the second yarn can be reverse-wound around the first yarn with the first yarn as the center line. In the fabric woven from this composite yarn, the resistance of the interlacing points of the yarns in the fabric is mainly the contact resistance of the first yarn material. When subjected to tension, the second yarn gradually wraps around the surface of the first yarn, so that a portion of the interlacing points of the yarns are the contact resistance of the second yarn material. Under continued tension, the second yarn completely wraps around the surface of the first yarn, and the resistance of the interlacing points of the yarns is completely determined by the second yarn. or, With the first yarn as the center line, the second yarn is wound around the first yarn, and under the action of force, the first yarn can be reverse-wound around the second yarn with the second yarn as the center line; in the fabric woven from this composite yarn, the resistance of the interlacing points of the yarns in the fabric is mainly the contact resistance of the second yarn material; when subjected to tension, the first yarn gradually wraps around the surface of the second yarn, so that some of the interlacing points of the yarns are the contact resistance of the first yarn material; under continued tension, the first yarn completely wraps around the surface of the second yarn, and the resistance of the interlacing points of the yarns is completely determined by the first yarn.

2. The flexible strain-sensing composite yarn according to claim 1, characterized in that, The first elastic force is less than the second elastic force; With the second yarn as the center line, the first yarn is spirally wound and covers the second yarn.

3. The flexible strain-sensing composite yarn according to claim 2, characterized in that, The flexible strain-sensing composite yarn has two states: In the first state, the second yarn is straightened, and the first yarn completely covers the second yarn in a winding manner; In the second state, the first yarn is straightened and the second yarn is wrapped around the second yarn. The flexible strain-sensing composite yarn can switch from a first state to a second state under stress, and return from the second state to the first state when the stress is removed.

4. The flexible strain-sensing composite yarn according to claim 1, characterized in that, The first elastic force is greater than the second elastic force; With the first yarn as the center line, the second yarn is spirally wound around and covers the first yarn.

5. The flexible strain-sensing composite yarn according to claim 1, characterized in that, The first yarn is evenly wound around the second yarn; or, the second yarn is evenly wound around the first yarn.

6. The flexible strain-sensing composite yarn according to claim 1, characterized in that, The color of the first yarn is different from the color of the second yarn; and / or, The shape of the first yarn is different from that of the second yarn.

7. The flexible strain-sensing composite yarn according to claim 1, characterized in that, The first yarn is selected from: pure metal yarn, pure carbon fiber yarn, silver-plated yarn, or blended yarn; the second yarn is selected from: spandex core-spun yarn, textured yarn; or, The first yarn is selected from non-conductive polymer filaments or staple fibers, and the second yarn is selected from conductive polymer filaments or staple fibers; or... The second yarn is selected from: pure metal yarn, pure carbon fiber yarn, silver-plated yarn, or blended yarn; the first yarn is selected from: spandex core-spun yarn, textured yarn; or, The second yarn is selected from non-conductive polymer filaments or staple fibers, and the first yarn is selected from conductive polymer filaments or staple fibers.

8. A method for preparing a flexible strain-sensing composite yarn as described in any one of claims 1-7, characterized in that, include: A first yarn is provided, the first yarn having a first elastic force; A second yarn is provided, the second yarn having a second elastic force, one of the first yarn and the second yarn being a conductive yarn, and the other of the first yarn and the second yarn being an insulating yarn; Using the second yarn as the center line, the first yarn is wound around the second yarn; or, Using the first yarn as the center line, the second yarn is wound around the first yarn.

9. A flexible strain-sensing fabric, characterized in that, It is woven from the flexible strain-sensing composite yarn described in any one of claims 1-7.

10. The flexible strain-sensing fabric according to claim 9, characterized in that, The flexible strain sensing fabric is a woven or braided fabric.

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