A high-elastic conductive gel fiber, a preparation method and application thereof

Abstract

The application relates to the field of elastic conductive materials, in particular to a high-elastic conductive gel fiber as well as a preparation method and application thereof. The high-elastic conductive gel fiber comprises at least one conductive core and a skin layer wrapped outside the conductive core. The conductive core is integrally configured as a curled strip, is formed by solidification of a hydrogel, and comprises a first base body and a conductive medium doped in the first base body. The skin layer is formed by solidification of a long-strip-shaped hydrogel configured by a second base body, and the first base body and the second base body are both hydrophilic polymer. The high-elastic conductive gel fiber is formed by co-differential extrusion of a first gel precursor containing the first base body and the conductive medium and a second gel precursor containing the second base body into a long-strip-shaped sleeve, and then self-assembly of the hydrogel fiber formed in the sleeve in a coagulation liquid to form solidification. The high-elastic conductive gel fiber has good conductivity and elasticity, high practicability, and a simple configuration mode, and is easy to mass-produce.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of elastic conductive materials, in particular to a high-elastic conductive gel fiber and a preparation method and application thereof. BACKGROUND

[0002] Flexible electronics is a new technology that integrates electronic devices on a flexible substrate, which can maintain its electronic performance under conditions such as bending, folding, twisting, compression or stretching, and helps to improve the practicality of wearable devices. For example, flexible ion electronic sensor devices can provide more advanced biocompatible interfaces and intelligent human-computer interaction platforms by simulating the ion migration mechanism of biological tissues, and have wide application prospects in the fields of medical treatment, energy and information.

[0003] In the field of flexible electronics, materials with good elasticity and high conductivity are needed to realize the transmission of electric energy and electric signals. However, in the field of traditional materials, it is difficult for materials to have both elasticity and conductivity. At present, elastic materials are often used as a matrix and doped with conductive materials to improve the conductivity of the composite material. However, the elasticity of the elastic material will be greatly reduced after being doped with conductive materials, which is difficult to meet the application requirements. SUMMARY

[0004] The purpose of the present application is to provide a high-elastic conductive gel fiber with good elasticity and a preparation method and application thereof.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides the following technical solution:

[0006] A high-elastic conductive gel fiber, comprising:

[0007] At least one conductive core, comprising a first matrix and a conductive medium doped in the first matrix, the first matrix being a hydrophilic polymer, and the conductive core being integrally configured in a coiled strip shape and formed by solidification of a hydrogel;

[0008] A skin layer wrapped outside the conductive core and formed by solidification of a long strip-shaped hydrogel configured by a second matrix, the second matrix being a hydrophilic polymer.

[0009] Optionally, the first matrix and the second matrix are the same material.

[0010] Optionally, the first matrix comprises one or more of polyvinyl alcohol, polyurethane, polyhydroxyethyl methacrylate and sodium polyacrylate, and the conductive medium comprises one or more of conductive silver nanosheets, silver nanowires, single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0011] In a second aspect, the present application further provides a preparation method of the high-elastic conductive gel fiber described above, comprising:

[0012] dissolving the first matrix in a first solvent and adding the conductive medium to disperse into homogeneity to obtain a first gel precursor;

[0013] dissolving the second matrix in a second solvent to obtain a second gel precursor;

[0014] extruding the first gel precursor and the second gel precursor from an extrusion port into a long tubular sleeve to form a two-phase fluid, the two-phase fluid being immersed into a coagulation liquid after leaving the sleeve, the extrusion port comprising an outer port and at least one inner port sleeved inside the outer port, the first gel precursor being extruded from the inner port at a first pushing speed, and the second gel precursor being extruded from the outer port at a second pushing speed, the length of the second gel precursor extruded per unit time being less than the length of the first gel precursor extruded per unit time;

[0015] collecting the two-phase fluid after solidification to obtain the high-elastic conductive gel fiber.

[0016] Optionally, the first matrix and the second matrix are both sodium polyacrylate with an average molecular weight of any value between 150,000 and 30,000,000, the conductive medium is multi-walled carbon nanotube, and the first solvent and the second solvent are both deionized water.

[0017] Optionally, the ratio of the first pushing speed to the second pushing speed is any value between 5 and 20:1, the second pushing speed is any value between 0.01 cm / min and 0.05 cm / min, the axial length of the sleeve is any value between 6 cm and 13 cm, and the sleeve is a glass capillary tube.

[0018] Optionally, the first matrix is dissolved in a dispersion prepared from the conductive medium and the first solvent to form the first gel precursor, the pH of the dispersion is any value between 6 and 13, the mass ratio of the conductive medium to the first solvent is any value between 1 and 7:10, the mass ratio of the first matrix to the first solvent in the first gel precursor is any value between 0.1 and 5.0:100, the mass ratio of the second matrix to the second solvent in the second gel precursor is any value between 0.1 and 5.0:100, and the pH of the second gel precursor is any value between 12 and 14.

[0019] Optionally, the coagulation liquid comprises one or more of an aqueous ethanol solution with a concentration of any value between 50% and 100%, an aqueous methanol solution with a concentration of any value between 50% and 100%, an aqueous ethylene glycol solution with a concentration of any value between 50% and 100%, acetone, and DMF.

[0020] In a third aspect, the present application further provides the use of the high-elasticity conductive gel fiber as described above in a triboelectric sensor.

[0021] In a fourth aspect, the present application further provides the use of the high-elasticity conductive gel fiber as described above in a strain sensor.

[0022] According to the first aspect of the present application, the conductive core is doped with a conductive medium, so that the conductive core has good conductivity. Since the conductive core is curled, its total length is greater than the length of the skin layer. When the whole fiber is stretched along its axial direction, the conductive core is stretched to be straightened, its axial length increases but its total length remains unchanged. After the whole fiber is stretched to the point that the conductive core is straightened, the fiber is slightly elongated under the action of the tension, and at this time the fiber reaches its tensile limit. When the fiber is no longer under stress, the skin layer restores to its original state under the action of its own elasticity, thereby driving the conductive core to restore to its initial curled state. By providing a curled conductive core, the fiber is helped to have both good conductivity and elasticity.

[0023] According to the second aspect of the present application, the high-elasticity conductive gel fiber is prepared by the method of differential speed extrusion followed by solidification. The extruded second gel precursor adheres to the surface of the first gel precursor, and since the extrusion speed of the first gel precursor is faster, the extruded strip-shaped first gel precursor is curled. After immersion in the coagulation liquid, under the action of the non-solvent diffusion effect, the first gel precursor and the second gel precursor quickly remove the internal moisture, and the molecular chains of the first matrix and the second matrix shrink due to dehydration, and the high-elasticity conductive gel fiber is obtained after solidification. The method of differential speed extrusion for preparing the fiber is convenient and efficient, simple to operate, and helps to mass-produce the fiber.

[0024] According to the third aspect of the present application, the skin layer of the fiber is flexible, and when it comes into contact with a hard rubbing layer, due to the different binding abilities of the two materials to electrons, the electrons are transferred from one material to the other, causing the surfaces of the two materials to carry equal and opposite charges. Since the conductive core of the fiber has high conductivity, it can act as an electrode, and a potential difference is induced on it. This potential difference, after being detected by an external circuit, forms a measurable electrical signal corresponding to the external stimulus, and plays a sensing role.

[0025] According to the fourth aspect of the present application, during the process of gradually straightening the conductive core, the morphology of the conductive core changes, and the conductive ability changes, so that the conductive ability of the fiber is related to the tension it receives. Especially when the skin layer has conductivity, since the cross-sectional area of the skin layer decreases with stretching, the change in the conductive ability of the fiber is more obviously affected by the degree of deformation, and when the conductive core is stretched to breakage, the change in the conductive ability with strain will be further increased.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the preparation method of the highly elastic conductive gel fiber as shown in Embodiment 1 of the present invention;

[0028] Figure 2 This is an image of a nozzle extruding a two-phase fluid as shown in Embodiment 1 of the present invention;

[0029] Figure 3 The high-elastic conductive gel fiber ISIF shown in Embodiment 1 of the present invention 70 A partial view of the exterior;

[0030] Figure 4 The high-elastic conductive gel fiber ISIF shown in Embodiment 1 of the present invention 70 Polarizing microscope image;

[0031] Figure 5 The high-elastic conductive gel fiber ISIF shown in Embodiment 1 of the present invention 70 The curve of the rate of change of resistance as a function of the strain;

[0032] Figure 6 The high-elastic conductive gel fiber ISIF shown in Embodiment 1 of the present invention 70 The curve of the rate of change of resistance as a function of stretching with multiple different strains;

[0033] Figure 7 The high-elastic conductive gel fiber ISIF shown in Embodiment 1 of the present invention 70 The curve showing the change rate of resistance during multiple strain unloading cycles;

[0034] Figure 8 The high-elastic conductive gel fiber ISIF shown in Embodiment 1 of the present invention 70 The stress-strain curves from the elasticity experiment;

[0035] Figure 9 This is a signal output diagram of the flexible fabric in the triboelectric sensor as shown in Embodiment 1 of the present invention;

[0036] Figure 10 This is an external view of the fiber ICIF formed without a sleeve in Embodiment 2 of the present invention;

[0037] Figure 11 The stress-strain curves of tensile tests on various fibers as shown in Embodiments 1 and 2 of the present invention are shown.

[0038] Figure 12 Figure of the change of the conductivity of the various high-elastic conductive gel fibers shown in Embodiment One and Embodiment Two of the present application;

[0039] Figure 13 Figure of the partial appearance of the end of the various high-elastic conductive gel fibers shown in Embodiment One and Embodiment Three of the present application adjacent to the sleeve;

[0040] Figure 14 Figure of the partial appearance of the end of the various high-elastic conductive gel fibers shown in Embodiment One and Embodiment Four of the present application adjacent to the sleeve;

[0041] Figure 15 Figure of the scanning electron microscope of the cross section and longitudinal section of the high-elastic conductive gel fiber shown in Embodiment Five of the present application;

[0042] Figure 16 Figure of the appearance of the cross section of the high-elastic conductive gel fiber shown in Embodiment Six of the present application;

[0043] Figure 17 Figure of the electron microscope of the cross section of the high-elastic conductive gel fiber shown in Embodiment Six of the present application. DETAILED DESCRIPTION

[0044] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0045] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0046] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0047] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] This invention protects a highly elastic conductive gel fiber, comprising at least one conductive core and a sheath surrounding the conductive core. The conductive core includes a first matrix and a conductive medium doped in the first matrix, the first matrix being a hydrophilic polymer. The conductive core is integrally structured as a coiled elongated strip, formed by curing hydrogel. The sheath is formed by curing an elongated hydrogel constructed from a second matrix, and the second matrix is ​​also a hydrophilic polymer.

[0049] The conductive core is doped with a conductive medium, giving it good conductivity. Because the conductive core is curled, its total length is greater than the sheath length. When the fiber is stretched axially, the conductive core extends until it straightens, increasing its axial length but maintaining its total length. After the fiber is stretched to the point where the conductive core is straight, it elongates slightly under tension, reaching the fiber's tensile limit. When the fiber is no longer under stress, the sheath returns to its original shape due to its elasticity, causing the conductive core to return to its initial curled state. By incorporating a curled conductive core, the fiber achieves both good conductivity and elasticity.

[0050] In some embodiments, the first substrate and the second substrate are made of the same material, which helps to improve the compatibility between the conductive core and the skin, thereby improving the integrity of the high-elasticity conductive gel fiber and ensuring that the conductive core and the skin adhere to form a curled wavy or spiral shape.

[0051] In some embodiments, the first matrix includes one or more of polyvinyl alcohol, polyurethane, poly(hydroxyethyl methacrylate) and sodium polyacrylate, and the conductive medium includes one or more of conductive silver nanosheets, silver nanowires, single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0052] Secondly, the present invention also provides a method for preparing the above-mentioned highly elastic conductive gel fiber, comprising:

[0053] S1. Dissolve the first matrix in the first solvent and add a conductive medium to disperse it until homogeneous to obtain the first gel precursor.

[0054] S2. Dissolve the second matrix in the second solvent to obtain the second gel precursor.

[0055] S3, extruding the first gel precursor and the second gel precursor from the extrusion port to the long tubular sleeve to form a two-phase fluid, the two-phase fluid being soaked in the coagulation liquid after leaving the sleeve, the extrusion port comprising an outer port and at least one inner port sleeved on the inner side of the outer port, the first gel precursor being extruded from the inner port at a first pushing speed, and the second gel precursor being extruded from the outer port at a second pushing speed, the length of the second gel precursor extruded per unit time being less than the length of the first gel precursor extruded per unit time.

[0056] S4, collecting the two-phase fluid after solidification to obtain the high-elastic conductive gel fiber.

[0057] The high-elastic conductive gel fiber is prepared by the method of differential extrusion and subsequent solidification, the extruded second gel precursor is adhered to the surface of the first gel precursor, the extruded length of the first gel precursor is greater than that of the second gel precursor, and the extruded second gel precursor is adhered to and wrapped around the extruded first gel precursor, so that the axial lengths of the extruded first gel precursor and the extruded second gel precursor are similar, thereby causing the extruded strip-shaped first gel precursor to curl. After soaking in the coagulation liquid, the first gel precursor and the second gel precursor quickly remove the internal moisture under the action of the non-solvent diffusion effect, the molecular chains of the first matrix and the second matrix are dehydrated and shrunk, and the high-elastic conductive gel fiber is obtained after solidification. The fiber is prepared by the method of differential extrusion, which is convenient, efficient and simple to operate, and is helpful for batch production of the fiber.

[0058] In some embodiments, the first matrix and the second matrix are both sodium polyacrylate with an average molecular weight of any value in the range of 150,000 to 30 million, the conductive medium is multi-walled carbon nanotube, and the first solvent and the second solvent are both deionized water. The average molecular weight of the sodium polyacrylate may, for example, be any value in the range of 150,000, 500,000, 1 million, 5 million, 10 million, 20 million and 30 million.

[0059] In some embodiments, the ratio of the first pushing speed to the second pushing speed is any value in the range of (5-20):1, for example, any value in the range of (5:1), (10:1), (15:1) and (20:1), the second pushing speed is any value in the range of 0.01 cm / min to 0.05 cm / min, for example, any value in the range of 0.01 cm / min, 0.02 cm / min, 0.03 cm / min, 0.04 cm / min and 0.05 cm / min, the axial length of the sleeve is any value in the range of 6 cm to 13 cm, for example, any value in the range of 6 cm, 7 cm, 8 cm, 9 cm, 10 cm and 13 cm, and the sleeve is a glass capillary tube.

[0060] By restricting the ratio of the first pushing speed to the second pushing speed and the value of the ratio, and restricting the axial length and material of the sleeve, the wall shear force of the sleeve and the shell hydrogel is moderate, and the restraining ability of the second gel precursor to the first gel precursor is moderate, so as to ensure that the conductive core is in a curled wave shape or a spiral shape.

[0061] In some embodiments, the first base is dissolved in a dispersion liquid prepared from the conductive medium and the first solvent to form the first gel precursor, the pH value of the dispersion liquid is any one of 6-13, for example, any one of 6, 8, 10, 12 and 13, the mass ratio of the conductive medium to the first solvent is any one of (1-7):10, for example, any one of (1:10), (2:10), (3:10), (4:10), (5:10), (6:10) and (7:10), the mass ratio of the first base to the first solvent in the first gel precursor is any one of (0.1-5.0):100, for example, any one of (0.1:100), (0.5:100), (1.0:100), (2.0:100), (3.0:100) and (5.0:100), the mass ratio of the second base to the second solvent in the second gel precursor is any one of (0.1-5.0):100, for example, any one of (0.1:100), (0.5:100), (1.0:100), (2.0:100), (3.0:100) and (5.0:100), and the pH value of the second gel precursor is any one of 12-14, for example, any one of 12, 13 and 14.

[0062] By restricting the concentration and pH value of sodium polyacrylate in the first gel precursor and the second gel precursor, the viscosity of the first gel precursor and the second gel precursor can be controlled, so that the conductive core is easily formed. At different pH values, the conformation of the molecular chain of sodium polyacrylate is different. When the pH value is any one of 6-13, the molecular chain of sodium polyacrylate is curled, and it is easier to form a curled conductive core. When the pH value is any one of 12-14, the molecular chain of sodium polyacrylate is a straight chain, which helps to improve the elasticity of the skin layer.

[0063] In some embodiments, the coagulation liquid includes one or more of an ethanol aqueous solution with a concentration of any one of 50%-100%, a methanol aqueous solution with a concentration of any one of 50%-100%, a glycol aqueous solution with a concentration of any one of 50%-100%, acetone and DMF. The concentration of the ethanol aqueous solution, the methanol aqueous solution and the glycol aqueous solution may, for example, be any one of 50%, 60%, 70%, 80%, 90% and 100%. This helps to improve the efficiency of dehydrating and curing the hydrogel into fibers.

[0064] In a third aspect, the present application further provides the use of the high-elasticity conductive gel fiber in a triboelectric sensor.

[0065] According to the third aspect of the present application, the skin layer of the fiber is flexible, and when it is in contact with a hard triboelectric layer, due to the different binding abilities of the two materials to electrons, the electrons are transferred from one material to another, so that the surfaces of the materials are respectively charged with equal and opposite charges. Since the conductive core of the fiber has high conductivity, it can act as an electrode, and a potential difference is induced on it. The potential difference is detected by an external circuit to form a measurable electrical signal corresponding to the external stimulus, which plays a sensing role.

[0066] In a fourth aspect, the present application further provides the use of the high-elasticity conductive gel fiber in a strain sensor.

[0067] During the gradual straightening of the conductive core, the morphology of the conductive core changes, and the conductive ability changes, thereby associating the conductive ability of the fiber with the tension it receives. Especially when the skin layer has conductivity, the change of the conductive ability of the fiber is more obviously affected by the degree of deformation due to the decrease of the cross-sectional area of the skin layer with stretching, and the change of the conductive ability with strain will be further increased when the conductive core is stretched to break.

[0068] For details, please refer to the following examples.

[0069] Example 1

[0070] Please refer to Figure 1 The preparation method of the high-elasticity conductive gel fiber shown in a preferred embodiment of the present application comprises:

[0071] S1, dissolving the first base in the first solvent and adding the conductive medium to disperse to homogeneity to obtain a first gel precursor.

[0072] S2, dissolving the second base in the second solvent to obtain a second gel precursor.

[0073] S3, extruding the first gel precursor and the second gel precursor from an extrusion port to a long tubular sleeve to form a two-phase fluid, and immersing the two-phase fluid in a coagulation liquid after leaving the sleeve, the extrusion port comprising an outer port and at least one inner port sleeved on the inner side of the outer port, the first gel precursor being extruded from the inner port at a first extrusion speed, and the second gel precursor being extruded from the outer port at a second extrusion speed, the length of the second gel precursor extruded per unit time being less than the length of the first gel precursor extruded per unit time.

[0074] S4, collecting the two-phase fluid after solidification to obtain a high-elasticity conductive gel fiber.

[0075] In step S1, sodium polyacrylate with an average molecular weight of about 6 million was used as the first matrix. Different amounts of multi-walled carbon nanotubes (MWCNTs) were uniformly added to deionized water, and ultrasonic treatment was performed under an ice water bath, with a switch cycle of 5s / 2s, for 50 min. The pH value of the dispersion was adjusted to 13.42 with 1 mol / L sodium hydroxide solution, and the first matrix was added and dissolved at 60°C. After mechanical stirring for 5 h, a first gel precursor with a mass fraction of 2.5% sodium polyacrylate was obtained.

[0076] In step S2, sodium polyacrylate with the same as the first matrix was used as the second matrix. The second matrix was dissolved in deionized water at 60°C, and after fully dissolved under mechanical stirring, a 2.5% sodium polyacrylate solution was obtained. A portion of the sodium polyacrylate solution was added dropwise with 1 mol / L sodium hydroxide solution to obtain a second gel precursor with a pH value of 9.16.

[0077] In step S3, a customized nozzle was used for extrusion of the first gel precursor and the second gel precursor. Please refer to Figure 2 , the nozzle includes coaxial outer port, inner port and sleeve. The outer port is sleeved outside the inner port, and the sleeve is nested outside the outer port. The diameter of the inner port is 0.5 mm, the diameter of the outer port is 2.85 mm, the sleeve is a capillary glass tube with a diameter of 0.9 mm, and the axial length of the sleeve from the outer port to the distal end is 9 cm. The first gel precursor is extruded from the inner port into the sleeve at a speed of 0.5 cm / min, and the second gel precursor is extruded from the outer port into the sleeve at a speed of 0.05 cm / min. In the sleeve, the first gel precursor and the second gel precursor are self-assembled in situ, the second gel precursor wraps the first gel precursor to form a two-phase fluid, and the two-phase fluid flows out from the distal end of the sleeve into the coagulation liquid. The coagulation liquid is a 90% concentration methanol aqueous solution.

[0078] In step S4, after the two-phase fluid is soaked in the coagulation liquid for about 30 min, the obtained high-elastic conductive gel fiber is collected by a roller. The high-elastic conductive gel fiber is exposed to the ambient air with an ambient humidity of 65%.

[0079] When the mass fraction of MWCNTs in the dispersion is 70%, the obtained high-elastic conductive gel fiber is named ISIF 70 .

[0080] Please refer to Figure 3 , it can be seen that ISIF 70 has a transparent skin layer and a black wavy conductive core, and the skin layer wraps the outer layer of the conductive core.

[0081] Please refer to Figure 4 , under a polarizing microscope, ISIF 70It can be seen from the figure that during the strain induction process, the sodium polyacrylate molecular chain is highly oriented and arranged along the fiber direction, which indicates that the fiber with ultra-high molecular chain dense entanglement and strain-induced chain orientation can realize the reversibility of the arrangement of nanofibers during the loading-unloading process, and realizes the high stretchability of the high-elastic conductive gel fiber.

[0082] Please refer to Figure 5 , observe the ISIF 70 The appearance morphology when stretched to different strain amounts, and detect the change of the resistance change rate with the strain amount. It can be seen from the figure that as the strain amount of ISIF 70 increases gradually, the conductive core is gradually straightened, and then stretched to break. Before and after the conductive core is straightened, the correlation of the conductivity of ISIF 70 with the strain amount is different, because before the conductive core is straightened, the change of the conductivity is mainly caused by the change of the morphology of the skin layer, and the correlation with the conductive core is low, and after the conductive core is straightened, the conductive core is also stretched, the cross-sectional area is reduced, and the change amount of the conductivity of ISIF 70 is increased.

[0083] Please refer to Figure 6 , stretch ISIF 70 to different strain amounts, and detect and calculate the resistance change rate respectively. It can be seen from the figure that as the fiber is stretched repeatedly, the corresponding resistance change rate is similar when the fiber is stretched to the same strain amount each time, so it can be seen that the resistance value of ISIF 70 has a relatively stable corresponding relationship with the strain amount of stretching.

[0084] Please refer to Figure 7 , repeatedly stretch ISIF 70 to the same strain amount, and repeatedly stretch and release for a long time, and continuously detect and calculate the resistance change rate. It can be seen from the figure that the resistance change rate curve does not change much after multiple strain unloading cycles. Combined with the experimental results in Figure 6 , it is proved that ISIF 70 has excellent strain sensing stability and long-term stability as a sensitive element of a strain sensor.

[0085] Please refer to Figure 8 , stretch ISIF 70 to different strain amounts and release, and observe the elastic recovery. Stretch another ISIF 70 to a strain amount of 200%, and repeatedly stretch and release for 100 times, and observe the elastic recovery. It can be seen from the figure that after multiple strain loading-unloading cycles, ISIF 70 shows high elasticity and small hysteresis loop.

[0086] Referring to Figure 9 ISIF 70 A flexible fabric in the shape of a rectangle as a whole is woven by a weft-knitting method, and the flexible fabric is used as a first friction layer and an electrode at the same time, and a polyvinylidene fluoride (PVDF) film is used as a second friction layer, so as to assemble a triboelectric sensor. The flexible fabric and the PVDF film are stacked, and a small gap exists between the two. The PVDF film is grounded through a metal electrode, and the flexible fabric is connected to an external circuit. Pressure is applied to the flexible fabric to make it contact with the PVDF film, and the external circuit is detected for an electrical signal. As can be seen from the figure, ISIF 70 Sensitivity and stable output can be realized in the triboelectric sensor.

[0087] As can be seen, the high-elastic conductive gel fiber in the embodiment has good elasticity, toughness and conductivity.

[0088] Example Two

[0089] The difference between the embodiment and Example One is that:

[0090] When the mass fraction of MWCNTs in the dispersion liquid is 10%, the high-elastic conductive gel fiber obtained is named ISIF 10 ; when the mass fraction of MWCNTs in the dispersion liquid is 30%, the high-elastic conductive gel fiber obtained is named ISIF 30 ; when the mass fraction of MWCNTs in the dispersion liquid is 50%, the high-elastic conductive gel fiber obtained is named ISIF 50 ; and when the mass fraction of MWCNTs in the dispersion liquid is 80%, the high-elastic conductive gel fiber obtained is named ISIF 80 .

[0091] The inner opening of the nozzle is removed, and the first gel precursor and the second gel precursor are respectively extruded from the outer opening to the sleeve, and then collected after immersion and solidification in the coagulation liquid, to obtain a fiber PANa-MWCNT containing MWCNTs and a fiber PANa not containing MWCNTs. The mass fraction of MWCNTs in the dispersion liquid corresponding to PANa-MWCNT is 70%. The same first gel precursor and the second gel precursor as ISIF 70 are extruded from the nozzle at the same flow rate, and the nozzle is not sleeved with a sleeve, and the obtained fiber is named ICIF. Referring to Figure 10It can be seen that the inner core of the ICIF is in the shape of a long strip close to a straight line. This is because the extruded second gel precursor is not constrained by the sleeve, and the pushing speed is not restricted by the sleeve. In addition, the second gel precursor has good fluidity, which leads to the fact that it cannot form a curled structure by blocking the axial extension of the first gel precursor, but instead is elongated axially to form a fiber with a large length under the driving of the first gel precursor.

[0092] See Figure 11 , the stress-strain curves of PANa, PANa-MWCNT, ICIF, ISIF 10 , ISIF 30 , ISIF 50 , and ISIF 70 are drawn. It can be seen that, compared with PANa-MWCNT and ICIF, ISIF 10 , ISIF 30 , ISIF 50 , and ISIF 70 have better stretchability, and the higher the content of MWCNTs, the weaker the stretchability of the high-elastic conductive gel fiber. Compared with various high-elastic conductive gel fibers, PANa has better stretchability.

[0093] See Figure 12 , the conductivity of ISIF 10 , ISIF 30 , ISIF 50 , ISIF 70 , and ISIF 80 is detected respectively, and a line graph is drawn. It can be seen from the graph that ISIF 70 has the best conductivity. This is because as the content of the conductive medium increases, the conductivity of the conductive core gradually increases. When the content of the conductive medium is too high, agglomeration is likely to occur in the matrix, which cannot effectively form a continuous conductive path, affecting the overall conductivity.

[0094] Example Three:

[0095] The difference between this embodiment and Example One is that the extrusion speed of the first gel precursor in this embodiment is adjusted to 0.25 cm / min, 0.75 cm / min, and 1.00 cm / min respectively, so that the ratio Q of the extrusion speed of the first gel precursor to the second gel precursor is (5:1), (15:1), and (20:1) respectively. See Figure 13 It can be seen that the ratio of the extrusion speed of the first gel precursor to the second gel precursor has a great influence on the morphology of the conductivity.

[0096] Example Four:

[0097] The difference between the present embodiment and embodiment one is that the axial length L of the sleeve in the present embodiment is adjusted to 1 cm, 5 cm and 13 cm respectively. Please refer to Figure 14 It can be seen that the axial length of the sleeve has a great influence on the morphology of the electrical conductivity.

[0098] Embodiment five:

[0099] The difference between the present embodiment and embodiment one is that the conductive medium in the present embodiment is silver nanosheet. Please refer to Figure 15 The high-elastic conductive gel fiber obtained in the present embodiment is cut transversely and longitudinally, the cross section is observed under a scanning electron microscope, and the element analysis is performed on the longitudinal section. It can be seen from the figure that the conductive core of the high-elastic conductive gel fiber obtained in the present embodiment is wavy, and the distribution of silver element in the conductive core is relatively uniform. It can be seen in the transverse section that there are large cavities in the high-elastic conductive gel fiber, which is caused by the shape of sodium polyacrylate itself.

[0100] Embodiment six:

[0101] The difference between the present embodiment and embodiment one is that the nozzle of the present embodiment includes two inner openings which are flush with each other and separated from each other. Both inner openings are sleeved on the inner side of the outer opening, and the extension direction is parallel to the outer opening. The first gel precursor is extruded from the two inner openings respectively. Please refer to Figure 16 The high-elastic conductive gel fiber obtained in the present embodiment includes two conductive cores which are separated from each other.

[0102] Please refer to Figure 17 The transverse section of the high-elastic conductive gel fiber obtained in the present embodiment is observed under an electron microscope, it can be seen that the high-elastic conductive gel fiber in the present embodiment has two conductive cores with relatively dense cross sections, and the two conductive cores are separated from each other.

[0103] The present application has the advantages of providing a high-elastic conductive gel fiber with good electrical conductivity, elasticity and toughness, and a preparation method thereof. The high-elastic conductive gel fiber can sensitively and stably output electrical signals in a triboelectric sensor and a strain sensor. The high-elastic conductive gel fiber is easy to construct, the preparation method is suitable for large-scale production, the cost is low, and has high practical value.

[0104] The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0105] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing a highly elastic conductive gel fiber, characterized in that, The highly elastic conductive gel fiber comprises: At least one conductive core, including a first substrate and a conductive medium doped in the first substrate, wherein the conductive core is integrally constructed as a coiled strip and is formed by solidification of hydrogel; A skin layer, wrapped around the outside of the conductive core, is formed by solidifying a strip-shaped hydrogel constructed from a second matrix; The first substrate and the second substrate are made of the same material; The first matrix includes one or more of polyvinyl alcohol, polyurethane, poly(hydroxyethyl methacrylate) and sodium polyacrylate, and the conductive medium includes one or more of conductive silver nanosheets, silver nanowires, single-walled carbon nanotubes and multi-walled carbon nanotubes. The preparation method includes: The first matrix is ​​dissolved in a first solvent, and the conductive medium is added and dispersed until homogeneous to obtain a first gel precursor; The second matrix is ​​dissolved in the second solvent to obtain the second gel precursor; The first gel precursor and the second gel precursor are extruded from the extrusion port into a long strip sleeve to form a two-phase fluid. After leaving the sleeve, the two-phase fluid is immersed in a coagulation liquid. The extrusion port includes an outer port and at least one inner port sleeved inside the outer port. The first gel precursor is extruded from the inner port at a first propulsion speed, and the second gel precursor is extruded from the outer port at a second propulsion speed. The length of the second gel precursor extruded per unit time is less than the length of the first gel precursor extruded. The solidified two-phase fluid is collected to obtain the highly elastic conductive gel fiber.

2. The method for preparing the highly elastic conductive gel fiber as described in claim 1, characterized in that, Both the first matrix and the second matrix are sodium polyacrylate with an average molecular weight of 150,000 to 30 million, the conductive medium is multi-walled carbon nanotubes, and both the first solvent and the second solvent are deionized water.

3. The method for preparing highly elastic conductive gel fibers as described in claim 2, characterized in that, The ratio of the first propulsion speed to the second propulsion speed is any value in (5~20):1, the second propulsion speed is any value in 0.01 cm / min~0.05 cm / min, the axial length of the sleeve is any value in 6 cm~13 cm, and the sleeve is a glass capillary tube.

4. The method for preparing highly elastic conductive gel fibers as described in claim 2, characterized in that, The first matrix is ​​dissolved in a dispersion prepared with the conductive medium and the first solvent to form the first gel precursor. The pH of the dispersion is any value between 6 and 13. The mass ratio of the conductive medium to the first solvent is any value between 1 and 7:

10. The mass ratio of the first matrix to the first solvent in the first gel precursor is any value between 0.1 and 5.0:

100. The mass ratio of the second matrix to the second solvent in the second gel precursor is any value between 0.1 and 5.0:

100. The pH of the second gel precursor is any value between 12 and 14.

5. The method for preparing highly elastic conductive gel fibers as described in claim 2, characterized in that, The coagulating liquid includes one or more of the following: an aqueous solution of ethanol with a concentration of 50% to 100%, an aqueous solution of methanol with a concentration of 50% to 100%, an aqueous solution of ethylene glycol with a concentration of 50% to 100%, acetone, and DMF.

6. A highly elastic conductive gel fiber prepared by any one of claims 1-5.

7. The application of the highly elastic conductive gel fiber as described in claim 6 in triboelectric sensors.

8. The application of the highly elastic conductive gel fiber as described in claim 6 in strain sensors.

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