Ultrahigh-resolution strain sensing fiber and preparation method thereof

Abstract

The invention discloses an ultrahigh-resolution strain sensing fiber and a preparation method thereof, and the preparation method comprises the following steps: (1) preparing an elastomer solution as a matrix of the strain sensing fiber; (2) mixing and doping a multi-morphology conductive material and the elastomer solution obtained in the step (1) to form a mixed solution in which a conductive filler is uniformly dispersed; (3) the mixed solution obtained in the step (2) is subjected to a wet spinning technology, and a sensing form is formed in a coagulating bath in one step; and (4) after the fiber in the step (3) is completely formed, taking out and drying to obtain the strain sensing fiber internally embedded with the multi-morphology conductive material. According to the invention, a wet spinning process is utilized, and a multi-dimensional synergistic conductive network doped with a multi-morphology conductive material is constructed in the strain sensing fiber, so that not only can high sensitivity of the strain sensing fiber be realized, but also ultrahigh resolution is realized, and the ultrahigh resolution can still be kept under 20% tensile strain.

Description

Technical Field

[0001] The invention belongs to the field of electronic fibers, and in particular relates to an ultra-high-resolution strain sensing fiber and a preparation method thereof. Background Art

[0002] Electronic fabrics are very suitable for human-machine interfaces by virtue of the humanized characteristics of soft, comfortable and wearable textiles, and are an important technology in the field of wearable devices. In recent years, electronic fabrics combining textiles with electronic devices have been developing rapidly with the continuous maturity of textile, electronic, information, physics, materials and other technologies. Among them, electronic fibers with strain sensing function are an important component of electronic fabrics and an ideal platform for building human body sensor networks. The sensing fibers can be placed in various parts of the body to achieve distributed, multi-channel and multi-parameter sensing. At present, there are many methods focused on improving the sensitivity and sensing range of strain sensing fibers, but methods for improving strain detection resolution have not yet appeared. Patent CN 107287684 A discloses a high-stretch, high-sensitivity flexible force-sensitive sensing fiber and a preparation method thereof, by first preparing 1D / 2D conductive fillers into fibers using a wet spinning process, and then introducing 0D metal nanoparticles using a swelling adsorption-in-situ reduction method. The 1D / 2D conductive filler in this method is very small and will not affect the flexibility of the material. The 0D metal nanoparticles are only present at a certain depth on the surface of the material by the method of swelling adsorption-in-situ reduction. The construction of this 0D / 1D / 2D three-dimensional collaborative network synergistically ensures the high stretchability (stretching degree of more than 500%) and high sensitivity (sensitivity can reach more than 50) of the force-sensitive sensing fiber. However, although this method maintains high stretchability and high sensitivity, its 0D / 1D / 2D three-dimensional collaborative network is not constructed inside the fiber, and it is impossible to achieve high strain resolution and maintain high strain resolution under pre-stretching conditions. Summary of the invention

[0003] The purpose of the present invention is to provide an ultra-high resolution strain sensing fiber and a preparation method thereof. By utilizing a wet spinning process, a multi-dimensional synergistic conductive network doped with multi-morphological conductive materials is constructed inside the strain sensing fiber, which can not only achieve high sensitivity of the strain sensing fiber, but also achieve ultra-high resolution, and can still maintain ultra-high resolution under 20% tensile strain.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for preparing an ultra-high resolution strain sensing fiber comprises the following steps:

[0006] (1) preparing an elastomer solution as a matrix for strain sensing fibers;

[0007] (2) mixing and doping the multi-morphology conductive material with the elastomer solution obtained in step (1) to form a mixed solution in which the conductive filler is uniformly dispersed;

[0008] (3) the mixed solution obtained in step (2) is subjected to a wet spinning technique to form a sensing form in one step in a coagulation bath;

[0009] (4) After the fiber in step (3) is completely formed, it is taken out and dried to obtain a strain sensing fiber with a multi-morphology conductive material embedded therein.

[0010] Furthermore, in the step (1), the elastic polymer is dissolved in N,N-dimethylformamide (DMF) to prepare an elastomer solution, and the mass ratio of the elastic polymer to N,N-dimethylformamide (DMF) is 1:1 to 1:8.

[0011] Furthermore, the elastic high molecular polymer is one of thermoplastic polyurethane (TPU), polyurethane (PU), polycaprolactone (PCL), polyethylene (PE), and styrene-butadiene-styrene block copolymer (SBS).

[0012] Furthermore, in step (2), the multi-morphology conductive material includes metal ball conductive material, one-dimensional wire / tube conductive material, and two-dimensional sheet conductive material, and the mass ratio of the three is 1:0.05:0.02 to 1:0.5:0.3.

[0013] Furthermore, the metal ball conductive material is a metal material with a 0-dimensional spherical structure, which is a gold ball, a silver ball, a nickel ball, or a copper ball, and has a particle size of 100 nanometers to 20 micrometers.

[0014] Furthermore, the one-dimensional wire / tube conductive material is a one-dimensional wire-shaped or tube-shaped material, which is one of gold nanowires, silver nanowires, copper nanowires, and carbon nanotubes.

[0015] Furthermore, the two-dimensional sheet material is a material in the shape of a two-dimensional sheet, which is one of a graphite sheet, a single-layer graphene sheet, a single-layer MXene sheet, a gold nanosheet and a silver nanosheet.

[0016] Furthermore, in the step (2), the mass ratio of the multi-morphology conductive material to the elastomer solution is 1:2 to 4:1.

[0017] Furthermore, in the step (3), water is used as the coagulation bath.

[0018] Furthermore, in step (4), the drying temperature is 60° C. and the drying time is 4 hours.

[0019] An ultra-high-resolution strain sensing fiber prepared by the method.

[0020] Since the multi-morphology conductive materials together form a uniform multi-dimensional cooperative conductive network inside the strain sensing fiber, when the strain sensing fiber is subjected to tensile strain, the internal multi-dimensional cooperative conductive network works together, so that the strain sensing fiber can still achieve a resolution of 0.01mm (0.025%) under 20% tensile strain.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0022] 1. The present invention uniformly dopes multi-morphology conductive materials inside the strain sensing fiber to construct a multi-dimensional collaborative conductive network, thereby ensuring that the strain sensing fiber can still achieve a resolution of 0.01 mm (0.025%) under a 20% tensile strain.

[0023] 2. Zero-dimensional metal spheres, one-dimensional wires / tubes, and two-dimensional sheet-like conductive fillers are embedded inside the strain sensing fiber polymer substrate. Compared with being attached to the surface, they are more secure and stable inside.

[0024] 3. It is manufactured by wet spinning process in one step, which is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the wet spinning process of the present invention;

[0026] Figure 2 is a scanning electron microscope (SEM) characterization image of the strain sensing fiber of the present invention;

[0027] Figure 3 This is a SEM characterization image of the zero-dimensional metal sphere, one-dimensional wire / tube, and two-dimensional sheet-like conductive filler embedded in the strain sensing fiber of the present invention;

[0028] Figure 4 is a resistance change curve of the strain sensing fiber of the present invention under tensile strain;

[0029] Figure 5 It is a strain resolution curve test diagram of the strain sensing fiber of the present invention;

[0030] Figure 6 This is a test diagram of the resolution curve of the strain sensing fiber of the present invention under 20% tensile strain;

[0031] Figure 7 It is a schematic diagram of the conductivity change of the conductive material inside the strain sensing fiber of the present invention with the tensile strain. DETAILED DESCRIPTION

[0032] The present invention will be further explained below in conjunction with the following examples. The present invention can be better understood according to the following examples.

[0033] Example 1

[0034] like Figure 1 As shown, a method for preparing an ultra-high resolution strain sensing fiber comprises the following steps:

[0035] (1) First, thermoplastic polyurethane (TPU) and N,N-dimethylformamide (DMF) are mixed in a mass ratio of 1:4 and dissolved to prepare an elastomer solution as the matrix of the strain sensing fiber.

[0036] (2) Then, 1 micron metal silver balls, carbon nanotubes, and graphite sheets are mixed in a mass ratio of 1:0.08:0.2 to form a multi-morphology conductive material, and the multi-morphology conductive material is mixed with an elastomer solution in a mass ratio of 1:1, and doped to form a mixed solution in which the conductive filler is uniformly dispersed.

[0037] (3) the mixed solution obtained in step (2) is subjected to wet spinning technology, wherein the inner diameter of the wet spinning needle is 500 μm, water is used as a coagulation bath, and the mixed solution is extruded in water to form fibers;

[0038] (4) Finally, after the fiber in step (3) is completely formed in a water coagulation bath for 1 hour, it is taken out and dried in an oven at 60° C. for 4 hours to obtain a strain sensing fiber with a multi-morphology conductive material embedded therein.

[0039] The scanning electron microscope (SEM) characterization image of the strain sensing fiber prepared in the embodiment is as follows: Figure 2 The SEM characterization of zero-dimensional metal spheres, one-dimensional wires / tubes, and two-dimensional sheet-like conductive fillers embedded in the strain sensing fiber is shown in Figure 2. Figure 3 The resistance curve of the strain sensing fiber under tensile strain is shown in Figure 4 The strain resolution curve test diagram of the strain sensing fiber is shown in Figure 5 The resolution curve test of the strain sensing fiber under 20% tensile strain is shown in Figure 6 shown.

[0040] like Figure 7As shown in the figure, the specific strain sensing mechanism of the strain sensing fiber is: when stretched, the connection between the metal balls, one-dimensional wires / tubes, and two-dimensional sheet-like mixed conductive materials inside the strain sensing fiber will be disconnected, thereby changing the formation of the conductive path and realizing the strain sensing function. The metal ball-metal ball type conductive path is very easy to change under strain. Although it can achieve a very high resolution, its strain sensing range is low. The one-dimensional wire / tube-one-dimensional wire / tube conductive path is not easy to change under strain, and it is difficult to achieve a good resolution. Here, a synergistic conductive network of multi-dimensional conductive materials is constructed by mixing metal balls, one-dimensional wires / tubes, and two-dimensional sheets. Under a small strain stretch, the connection between balls, balls and wires, and balls and sheet materials is broken first, resulting in a reduction in the conductive path and an increase in resistance; as the strain stretch increases, the connection between sheets, sheets and wires, and wires and wires is broken, resulting in a further reduction in the conductive path and a continued increase in resistance; thus, the strain sensing fiber can still achieve a resolution of 0.01mm (0.025%) under a 20% tensile strain.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an ultra-high resolution strain sensing fiber, characterized in that: The following steps are involved: (1) preparing an elastomer solution as a matrix for strain sensing fibers; (2) mixing and doping the multi-morphology conductive material with the elastomer solution obtained in step (1) to form a mixed solution in which the conductive filler is uniformly dispersed; (3) the mixed solution obtained in step (2) is subjected to a wet spinning technique to form a sensing form in one step in a coagulation bath; (4) After the fiber in step (3) is completely formed, it is taken out and dried to obtain a strain sensing fiber with a multi-morphology conductive material embedded therein.

2. The method for preparing an ultra-high resolution strain sensing fiber according to claim 1, characterized in that: In the step (1), the elastic polymer is dissolved in N,N-dimethylformamide to prepare an elastomer solution, and the mass ratio of the elastic polymer to the N,N-dimethylformamide is 1:1 to 1:

8.

3. The method for preparing an ultra-high resolution strain sensing fiber according to claim 2, characterized in that: The elastic high molecular polymer is one of thermoplastic polyurethane, polyurethane, polycaprolactone, polyethylene, and styrene-butadiene-styrene block copolymer.

4. The method for preparing an ultra-high resolution strain sensing fiber according to claim 1, characterized in that: In the step (2), the multi-morphology conductive material includes metal ball conductive material, one-dimensional wire / tube conductive material, and two-dimensional sheet conductive material, and the mass ratio of the three is 1:0.05:0.02 to 1:0.5:0.

3.

5. The method for preparing an ultra-high resolution strain sensing fiber according to claim 4, characterized in that: The metal ball conductive material is a metal material with a 0-dimensional spherical structure, which is a gold ball, a silver ball, a nickel ball, or a copper ball, and has a particle size of 100 nanometers to 20 micrometers; The one-dimensional wire / tube conductive material is a one-dimensional wire-shaped or tube-shaped material, which is one of gold nanowires, silver nanowires, copper nanowires, and carbon nanotubes; The two-dimensional sheet-like conductive material is a material in a 2-dimensional sheet shape, and is one of a graphite sheet, a single-layer graphene sheet, a single-layer MXene sheet, a gold nanosheet, and a silver nanosheet.

6. The method for preparing an ultra-high resolution strain sensing fiber according to claim 1 or 4, characterized in that: In the step (2), the mass ratio of the multi-morphology conductive material to the elastomer solution is 1:2 to 4:

1.

7. The method for preparing an ultra-high resolution strain sensing fiber according to claim 1, characterized in that: In the step (3), water is used as the coagulation bath.

8. The method for preparing an ultra-high resolution strain sensing fiber according to claim 1, characterized in that: In the step (4), the drying temperature is 60° C. and the drying time is 4 hours.

9. An ultra-high-resolution strain sensing fiber prepared by the method of claim 1.

10. The ultra-high resolution strain sensing fiber according to claim 9, characterized in that: The strain sensing fiber can still achieve a resolution of 0.01 mm under a 20% tensile strain.

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