Preparation method and application of fiber with mixed conductive network

Abstract

The invention discloses a preparation method and application of fibers with a mixed conductive network, and the preparation method comprises the following steps: (1) adding AgNO3 into a PVA solution dissolved in EG and deionized water, and stirring and mixing to prepare an AgNO3 / PVA / EG core layer spinning solution; (2) adding TPU (Thermoplastic Polyurethane) into DMF (Dimethyl Formamide), and stirring and mixing to obtain a TPU / DMF cortex spinning solution; (3) the TPU / DMF skin layer spinning solution and the AgNPs / PVA core layer spinning solution are extruded into a deionized water coagulating bath through a coaxial needle at the speed of 400 [mu] L.min <-1 > and the speed of 200 [mu] L.min <-1 > respectively, and primary filaments are obtained; and (4) carrying out heating treatment on the primary filaments, and then carrying out freeze thawing treatment to obtain the HCNF. Compared with the prior art, the HCNF prepared by the preparation method of the fibers with the mixed conductive network has high safety, excellent low-temperature tolerance and excellent strain sensing performance, can be used as a flexible wearable strain sensing material, and can be made into a strain sensor for monitoring human motion.

Description

Technical Field

[0001] The present invention relates to the technical field of stretchable conductive fibers, and in particular to a preparation method and application of fibers having a mixed conductive network. Background Art

[0002] With the rapid development of materials science and electronic manufacturing, flexible wearable strain sensing materials have shown broad application prospects in the fields of human motion monitoring, health monitoring and human-computer interaction due to their ability to respond to external stimuli. However, traditional strain sensing materials are based on metals or semiconductors, which can usually only sense small deformations of small strains, and the rigidity of the materials themselves often affects the comfort of wearing. In addition, in practical applications, the requirements for the stretchability, cyclic stability and biocompatibility of wearable strain sensing materials have also increased. Therefore, there is an urgent need to design effective strategies to prepare wearable strain sensing materials with high sensitivity and high stretchability.

[0003] Conductive materials are incorporated into the organogel matrix to give it excellent electrical properties, and organogel-based conductive materials can be manufactured and used as wearable strain sensing materials. However, traditional organogel-based conductive materials will inevitably freeze and lose their good properties in low-temperature environments, thus limiting their practical applications. In addition, organogel-based conductive materials also have the risk of leakage when in contact with human skin.

[0004] Therefore, how to prepare a flexible wearable strain sensing material with high safety, low temperature tolerance, high sensitivity and linearity is a problem to be solved urgently in the present invention. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation method of mixed conductive network fiber and its application to solve the problems in the prior art.

[0006] In a first aspect, the present invention provides a method for preparing a fiber having a mixed conductive network, comprising the following steps:

[0007] (1) adding AgNO3 to a PVA solution dissolved in EG and deionized water and stirring and mixing to prepare an AgNO3 / PVA / EG core layer spinning solution;

[0008] (2) adding TPU into DMF, and mixing by stirring to obtain a TPU / DMF skin spinning solution;

[0009] (3) The TPU / DMF skin spinning solution and the AgNPs / PVA core spinning solution were respectively passed through a coaxial needle at a speed of 400 μL min -1 and 200 μL·min -1 The primary silk is obtained by extruding it into a deionized water coagulation bath at a speed of

[0010] (4) The primary silk is subjected to a heating treatment and then a freeze-thaw treatment to obtain HCNF.

[0011] A method for preparing a mixed conductive network fiber as described above, wherein, preferably, the mass of the AgNO3 in step (1) is 0.1699 g.

[0012] In the method for preparing a mixed conductive network fiber as described above, preferably, the mass fraction of the PVA solution in step (1) is 5 wt %.

[0013] In the method for preparing a mixed conductive network fiber as described above, preferably, the stirring and mixing in step (1) is performed by using a magnetic stirrer for 30 minutes.

[0014] In the method for preparing a mixed conductive network fiber as described above, preferably, the mass fraction of the TPU / DMF skin spinning solution in step (2) is 15 wt%.

[0015] In the method for preparing mixed conductive network fibers as described above, preferably, the stirring time in step (2) is 12 hours.

[0016] In the method for preparing a mixed conductive network fiber as described above, preferably, the coaxial needle in step (3) has a specification of 17G / 21G.

[0017] In the method for preparing a mixed conductive network fiber as described above, preferably, the heating treatment time in step (4) is 10 minutes and the temperature is 40°C.

[0018] A method for preparing a mixed conductive network fiber as described above, wherein, preferably, the freezing time of the freeze-thaw treatment in step (4) is 8 hours, the temperature is -24°C, the thawing time is 2 hours, the temperature is room temperature, and the number of freeze-thaw treatments is 3 times.

[0019] In a second aspect, the present invention provides an application of a fiber having a mixed conductive network, including application of HCNF prepared by the aforementioned preparation method of a fiber having a mixed conductive network in human motion monitoring.

[0020] Compared with the prior art, the HCNF prepared by the preparation method of the mixed conductive network fiber in the present invention has high safety, excellent low-temperature tolerance and outstanding strain sensing performance, and can be used as a flexible wearable strain sensing material to be made into a strain sensor to monitor human movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a diagram showing the appearance of the HCNF prepared in Example 1;

[0022] Figure 2 It is the ionic / electronic mixed conductive network characterization of the HCNF prepared in Example 1;

[0023] Figure 3 is the conductivity of HCNF prepared in Example 1 at different temperatures;

[0024] Figure 4 is the tensile cycle curve of HCNF prepared in Example 1 at different strains and frequencies;

[0025] Figure 5 is the stretching cycle curve of HCNF prepared in Example 1 at different temperatures;

[0026] Figure 6 is a comparison curve of GF values ​​of the HCNF strain sensor prepared in Example 2;

[0027] Figure 7 is the relative resistance change curve corresponding to different strains of the HCNF strain sensor prepared in Example 2;

[0028] Figure 8 is the relative resistance change curve of the HCNF strain sensor prepared in Example 2 at different temperatures;

[0029] Fig. 9 is the working curve of the HCNF strain sensor in Example 3 for monitoring the bending motion of the finger;

[0030] Fig.10 is the working curve of the HCNF strain sensor in Example 3 for monitoring arm bending motion;

[0031] Fig.11 This is the working curve of the HCNF strain sensor in Example 3 monitoring the knee bending movement. DETAILED DESCRIPTION

[0032] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but should not be construed as limiting the present invention.

[0033] In a first aspect, the present invention provides a method for preparing a fiber having a mixed conductive network, comprising the following steps:

[0034] (1) Silver nitrate (AgNO3) is added to a polyethylene glycol (PVA) solution dissolved in ethylene glycol (EG) and deionized water, and the mixture is stirred to prepare an AgNO3 / PVA / EG core layer spinning solution.

[0035] (2) Adding thermoplastic polyurethane (TPU) fiber into N,N-dimethylformamide (DMF), and mixing by stirring to obtain a TPU / DMF skin spinning solution.

[0036] (3) The TPU / DMF skin spinning solution and the AgNPs / PVA core spinning solution were respectively passed through a coaxial needle at a speed of 400 μL min -1 and 200 μL·min -1 The initial silk was obtained by extruding it into a deionized water coagulation bath at a speed of

[0037] (4) The primary silk is subjected to a heating treatment and then a freeze-thaw treatment to obtain HCNF.

[0038] AgNO3 was added to the PVA solution dissolved in EG and H2O and stirred to obtain the AgNO3 / PVA / EG core spinning solution. TPU was dissolved in N,N-dimethylformamide (DMF) to obtain the TPU / DMF skin spinning solution. The AgNO3 / PVA / EG solution and the TPU / DMF solution were respectively passed through the inner and outer channels of the coaxial needle into the deionized water coagulation bath to obtain the primary yarn. After the use of the thermal reduction / cold cross-linking strategy, a fiber with a mixed conductive network was obtained. During the thermal reduction process, due to the presence of polyhydroxy alcohol, the Ag in the HCNF core liquid + It is partially reduced to AgNPs to form an ion / electron mixed conductive network. During the cold cross-linking process, H2O is frozen into ice, and the PVA chains dissolved in H2O are arranged closely in order. Subsequently, the ice melts into H2O, but the PVA chains are still closely arranged to form a physical cross-linking network. The ion / electron mixed conductive network is constructed in the physical cross-linking network, giving HCNF excellent strain sensing potential. The TPU skin encapsulates the core gel inside through intermolecular hydrogen bonds, effectively avoiding leakage of the core layer and direct contact with the human body. In addition, the interfacial effect between the skin and the core gives HCNF good mechanical properties. Thanks to the addition of EG, the HCNF sensor can also work stably at low temperatures.

[0039] In the embodiment provided in the present application, the mass of AgNO3 described in step (1) is 0.1699g; the mass fraction of the PVA solution described in step (1) is 5wt%; the stirring and mixing in step (1) is stirring using a magnetic stirrer, and the stirring time is 30min; the mass fraction of the TPU / DMF skin spinning solution described in step (2) is 15wt%; the stirring time described in step (2) is 12h; the coaxial needle specification described in step (3) is 17G / 21G; the heating treatment time described in step (4) is 10min, and the temperature is 40°C; the freezing time of the freeze-thaw treatment in step (4) is 8h, the temperature is -24°C, the thawing time is 2h, the temperature is room temperature, and the number of freeze-thaw treatments is 3 times.

[0040] In a second aspect, the present invention provides an application of a fiber having a mixed conductive network, including application of HCNF prepared by the aforementioned preparation method of a fiber having a mixed conductive network in human motion monitoring.

[0041] In the HCNF prepared by the above method, there is a good interface between the skin layer and the core layer, and the prepared HCNF has excellent mechanical properties. The HCNF can be tested for sensitivity (GF) within the strain range of 100%, with a measured value of 2.26, a linearity of 0.998, and a conductivity of 1.812S m -1 , which is attributed to the construction of an ion / electron mixed conductive network. Benefiting from the addition of EG, the HCNF sensor can work stably at -20°C. The good electromechanical properties enable the HCNF sensor to be used to monitor human motion. Therefore, the present invention can be used as a flexible wearable strain sensing material with high safety, excellent low temperature tolerance and excellent sensing performance, and can be applied to strain sensors for monitoring changes in human motion.

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] This embodiment discloses a method for preparing a hybrid conductive network fiber (HCNF), comprising the following steps:

[0045] 1) Adding AgNO3 to a PVA solution dissolved in EG and deionized water and stirring and mixing, to prepare an AgNO3 / PVA / EG core layer spinning solution.

[0046] 2) Add TPU into DMF and mix by stirring to obtain TPU / DMF skin spinning solution.

[0047] 3) The TPU / DMF skin spinning solution and the AgNPs / PVA core spinning solution were respectively passed through a coaxial needle at a speed of 400 μL·min -1 and 200 μL·min -1 The initial silk was obtained by extruding it into a deionized water coagulation bath at a speed of

[0048] 4) The primary silk is subjected to a heating treatment and then subjected to a freeze-thaw treatment to obtain HCNF.

[0049] The HCNF prepared in Example 1 was displayed in appearance, and the result was as follows: Figure 1shown; Figure 1 A is an optical photograph of the prepared HCNF; Figure 1 B is an optical photograph of a fabric woven from HCNF. Figure 1 A shows that the core gel is encapsulated in the TPU skin layer, and the core layer and skin layer of HCNF are tightly attached. Figure 1 B shows that HCNF has good flexibility, weavability and scalability. Figure 2 Characterization of HCNF core gel. Figure 2 A-2C are the UV spectrum, Ag fine spectrum and TEM images of the HCNF core gel, which together indicate that the ion / electronic mixed conductive network has been successfully constructed. The resistance of HCNF at different temperatures was tested and its conductivity was calculated, and the results were Figure 3 The results show that HCNF has good electrical conductivity even at low temperatures. The two ends of the HCNF prepared in Example 1 were connected to the upper and lower mechanical sensors of the universal testing machine, and the program was set at 20%, 40%, 60%, 80% and 100% strain, 50 mm min -1 Under the conditions of stretching cycle, we get Figure 4 A. Then set the program to 50% strain, frequency 0.01Hz, 0.05Hz, 0.10Hz and 0.50Hz, stretch cycle, and obtain Figure 4 B. Figure 4 A-4B shows that HCNF can work stably under different strains and frequencies and has good mechanical properties. The HCNF prepared in Example 1 was placed in a -30°C environment for 12 hours and then connected to the upper and lower mechanical sensors of an electronic universal testing machine at both ends. The tensile speed was set to 50 mm min -1 , under 50% strain condition, the cycle curve from -20℃ to room temperature was tested, and the Figure 5 ,from Figure 5 It can be seen that HCNF can still work stably at different temperatures and has excellent stability.

[0050] Example 2

[0051] This embodiment discloses a method for preparing a strain sensor based on HCNF assembly, comprising the following steps:

[0052] 1) The HCNF prepared in Example 1 is cut short to obtain a fiber segment X1 with a length of 3 cm;

[0053] 2) Inserting the two ends of the fiber segment X1 into copper wires coated with conductive glue to obtain a fiber segment X2;

[0054] 3) Fix the two ends of the fiber segment X2 with epoxy glue to obtain the device X3, which is a strain sensor assembled based on HCNF.

[0055] Connect the device X3 to the digital source meter and universal testing machine, and control the stretching rate to 50 mm / min. -1 , the tensile strain is 100%, and the relative resistance change and strain curve is obtained, and the corresponding sensitivity is calculated based on it. Figure 6 The results show that the HCNF strain sensor prepared in the embodiment of the present invention has high sensitivity and high linearity in a wide strain range, which is attributed to the successful construction of the ionic / electronic mixed conductive network. The stretching rate is controlled to be 50 mm min -1 , the tensile strain is increased from 10% to 80%, and the relative resistance change curve corresponding to the output strain is obtained Figure 7 The results show that the HCNF strain sensor prepared in the embodiment of the present invention can efficiently convert strain stimulation into electrical signals, has a stable strain stimulation response and a wide strain detection range. The HCNF strain sensor prepared in the embodiment of the present invention was placed in a -30°C environment for 12 hours and then connected to a digital source meter and a universal testing machine. The stretching rate was controlled to be 50 mm / min. -1 , tensile strain is 50%, and the relative resistance change from -20℃ to room temperature is tested, and the result is Figure 8 The results show that the HCNF strain sensor prepared in the embodiment of the present invention can still work stably under low temperature conditions, has good low temperature tolerance, and the signal output is less affected by temperature, and has the potential to be used in complex environments.

[0056] Example 3

[0057] This embodiment discloses the prepared HCNF strain sensor for monitoring human joint bending motion, as follows:

[0058] The device X3 prepared in the above embodiment 2 is connected to the digital source meter and the skin of the finger, and a series of working curves are obtained by controlling the bending of the finger. Fig. 9 The results show that the HCNF strain sensor made in the embodiment of the present invention can well monitor the tiny bending movement of the finger. The device X3 made in the above embodiment 2 is connected to the digital source meter and the skin of the arm, and a series of working curves are obtained by controlling the bending of the arm. Fig.10 The results show that the HCNF strain sensor prepared in the embodiment of the present invention can well monitor the bending movement of the wrist. The device X3 prepared in the above embodiment 2 is connected to the digital source meter and the skin of the knee, and a series of working curves are obtained by controlling the bending of the knee, such as Fig.11 As shown, it can be seen that the HCNF strain sensor made in the embodiment of the present invention can well monitor the knee bending movement. The above results show that the HCNF strain sensor can be used to monitor the joint movement of the human body and sense the small and large deformation movements in daily exercise.

[0059] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made according to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. A method for preparing a mixed conductive network fiber, characterized in that: The following steps are involved: (1) Adding AgNO3 to a PVA solution dissolved in EG and deionized water and stirring to prepare an AgNO3 / PVA / EG core layer spinning solution; (2) Adding TPU into DMF, and mixing by stirring to obtain a TPU / DMF skin spinning solution; (3) The TPU / DMF skin spinning solution and the AgNPs / PVA core spinning solution were respectively passed through a coaxial needle at a speed of 400 μL min -1 and 200 μL·min -1 The primary silk is obtained by extruding it into a deionized water coagulation bath at a speed of (4) The primary silk is heated and then freeze-thawed to obtain HCNF.

2. The method for preparing a fiber having a mixed conductive network according to claim 1, characterized in that: The mass of AgNO3 in step (1) is 0.1699 g.

3. The method for preparing the mixed conductive network fiber according to claim 1, characterized in that: The mass fraction of the PVA solution in step (1) is 5 wt%.

4. The method for preparing the mixed conductive network fiber according to claim 1, characterized in that: The stirring and mixing in step (1) is performed by using a magnetic stirrer, and the stirring time is 30 minutes.

5. The method for preparing the mixed conductive network fiber according to claim 1, characterized in that: The mass fraction of the TPU / DMF skin spinning solution in step (2) is 15 wt%.

6. The method for preparing the mixed conductive network fiber according to claim 1, characterized in that: The stirring time in step (2) is 12 hours.

7. The method for preparing the mixed conductive network fiber according to claim 1, characterized in that: The coaxial needle in step (3) has a specification of 17G / 21G.

8. The method for preparing the mixed conductive network fiber according to claim 1, characterized in that: The heating treatment time in step (4) is 10 min and the temperature is 40°C.

9. The method for preparing a mixed conductive network fiber according to claim 1, characterized in that: The freezing time of the freeze-thaw treatment in step (4) is 8 hours, the temperature is -24°C, the thawing time is 2 hours, the temperature is room temperature, and the number of freeze-thaw treatments is 3 times.

10. An application of a low temperature resistant strain sensing fiber, characterized in that: The invention comprises the use of HCNF prepared by the preparation method of mixed conductive network fiber according to any one of claims 1 to 9 in human motion monitoring.

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