Flexible sensing material with high stretchability, wide detection range and high sensitivity and preparation method

Abstract

The invention relates to the technical field of flexible sensing, in particular to a flexible sensing material with high stretchability, wide detection range and high sensitivity and a preparation method thereof.The high stretchability and high sensitivity can be achieved through a double-network structural design. After being mixed with thermoplastic polyurethane, the material is subjected to electrostatic spinning to form a first layer of physical cross-linked network and a conductive substrate, so that the material is endowed with high stretchability and initial conductivity; then, the substrate is immersed in an ultrasonic mixed solution containing carbon black and MXene, a second layer of physical and chemical cross-linked network is constructed through ultrasonic treatment, and functional groups of MXene and carbon black synergistically enhance chemical bonding, so that the sensitivity and the wide strain detection range are remarkably improved, and meanwhile, rapid response and cycling stability are kept. The problems that a traditional sensor is low in stretchability and narrow in detection range are solved, and the sensor is simple in preparation process, low in cost and suitable for the field of human motion monitoring and health management.

Description

Technical Field

[0001] The present invention relates to the field of flexible sensing technology, and in particular to a flexible sensing material with high stretchability, wide detection range and high sensitivity, and a preparation method thereof. Background Art

[0002] Flexible strain sensors are sensors that can measure deformation or strain of an object, typically made of flexible materials. They can be attached, implanted, or installed on surfaces or structures to detect deformation or strain. Flexible strain sensors play a vital role in various fields, including engineering, sports, and medicine, particularly in the medical and sports fields. In recent years, the continuous innovation and development of flexible strain sensors has driven the development of human health monitoring and electronic equipment towards greater intelligence, convenience, and comfort, bringing positive impacts to scientific and technological progress and human life.

[0003] However, current flexible sensor devices are limited by low stretchability, narrow detection range, and low sensitivity, limiting their application in cyclic human motion detection. For example, patent number CN116294958A discloses a flexible strain sensor with a wrinkled structure and anisotropy, and its preparation method. Using MXene, a highly sensitive and stretchable strain sensor is designed. The unique wrinkle, crack, and bridge structure of the MXene@MWCNT hybrid film is utilized to achieve high sensitivity, high stretchability, and good cyclic stability. Nano- / micro-scale cracks significantly enhance the resistance change rate of the hybrid film under stress through tunneling. This avoids the potential for non-detection under small strain conditions, resulting in a flexible sensing material with high performance even under small strains. However, the unique wrinkle-like microstructure of the resulting MXene@MWCNT hybrid film results in insufficient self-healing properties upon stretching, and the corresponding detectable strain range is limited, which remains a drawback to some extent. Therefore, the development of flexible strain sensing materials with high stretchability, wide detection range and high sensitivity is of great significance for monitoring large-scale human body movements and continuous repetitive movements. Summary of the Invention

[0004] The purpose of the present invention is to provide a flexible sensing material with high stretchability, wide detection range and high sensitivity and a preparation method. The flexible sensing material prepared based on the nano-level double network structure has high stretchability, fast response time, wide strain detection range, good cyclic stability, simple preparation process and low cost, and has application potential in the fields of human motion monitoring, health monitoring and management.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] A flexible sensing material with high stretchability, wide detection range and high sensitivity, comprising:

[0007] During the electrospinning process, carbon black particles are evenly dispersed in the thermoplastic polyurethane fibers. The high specific surface area of ​​carbon black and the physical adsorption of thermoplastic polyurethane molecular chains form the first layer of physical cross-linked network. At the same time, the tunneling effect between carbon black particles constructs a continuous first layer of conductive network, giving the base film initial conductivity and mechanical support. Figure 3 The figure shows an SEM image of the base film that constructs the first layer of cross-linked network. It can be clearly seen that the carbon black particles physically cross-link the fibers together, forming a tunneling effect between the carbon black particles.

[0008] Strengthening of the second layer of physical and chemical cross-linking network and conductive network: During ultrasonic treatment, the carbon black particles in the prefabricated mixed solution penetrate into the gaps between thermoplastic polyurethane fibers through ultrasonic dispersion, and further enhance the cross-linking density between fibers through physical adsorption; MXene nanosheets form chemical bonds with thermoplastic polyurethane molecular chains due to their rich surface functional groups (such as -OH, -O, etc.), constructing a second layer of chemical cross-linking network. At the same time, the high conductivity of MXene and the synergistic effect of carbon black form a second layer of composite conductive network, which significantly improves the conductive stability and strain response sensitivity of the material. Figure 4 Shown are the Fourier infrared spectra of the base film and the carbon black / thermoplastic polyurethane / carbon black / MXene film. It can be seen that compared with the base film and the final sensing material, the wavelengths at 2955 and 3327 disappear because the effective filling of MXene makes it impossible to project infrared rays, and the wavelengths at 1078 and 1223 shift to the left to 1063 and 1221 because -OH and thermoplastic polyurethane molecules have formed weak hydrogen bonds.

[0009] On the other hand, the present invention provides a method for preparing the above-mentioned flexible sensing material, comprising the following steps:

[0010] S1: preparing a mixed solution of N,N-dimethylformamide / tetrahydrofuran / carbon black;

[0011] S2: adding thermoplastic polyurethane to the mixed solution of step S1 after ultrasonic treatment, heating and stirring to dissolve, to prepare a thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution;

[0012] S3: pouring the dissolved solution in step S2 into a needle tube for electrospinning to obtain a carbon black / thermoplastic polyurethane spinning film substrate;

[0013] S4: placing the spun film in an oven for drying to obtain a dried carbon black / thermoplastic polyurethane spun film substrate;

[0014] S5: Preparation of prefabricated substrate spinning membrane ultrasonic mixture: anhydrous ethanol / carbon black / MXene mixed solution;

[0015] S6: immersing the spun film obtained in step S4 into the prefabricated base spinning film ultrasonic mixed solution obtained in S5 for ultrasonic treatment to obtain a carbon black / thermoplastic polyurethane / carbon black / MXene spun film;

[0016] S7: The carbon black / thermoplastic polyurethane / carbon black / MXene spun film of step S6 is taken out and placed in an oven for drying to obtain the textile flexible sensing material with high stretchability, wide detection range and high sensitivity.

[0017] Furthermore, in S1, 0.1-0.3 parts of carbon black particles are added by mass to a certain amount of a mixture of N,N-dimethylformamide and tetrahydrofuran, and the carbon black particles are ultrasonically dispersed at a power of 120 W for 30 minutes to obtain an N,N-dimethylformamide / tetrahydrofuran / carbon black mixed solution.

[0018] Furthermore, in S2, 1-3 parts by mass of thermoplastic polyurethane are added to the mixed solution prepared in S1, and the mixture is heated to 50° C. and stirred until completely dissolved to obtain a thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution.

[0019] Furthermore, in S3, the thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution prepared in S2 is poured into the needle tube of the electrospinning equipment for spinning, and the electrospinning parameters are controlled as follows: the screw position is 30 mm, the needle head is 25° to the horizontal direction, the temperature is controlled to 35°C, the humidity is controlled to 40%, the voltage is 15KV, the moving platform moving speed is 2 mm / s, the moving swing is 4 mm, the main pump pushing speed is 0.0003 mm / min, and the roller speed is 80 rpm / min to obtain a carbon black / thermoplastic polyurethane spinning film substrate.

[0020] Furthermore, in S4, the carbon black / thermoplastic polyurethane spun film substrate prepared in S3 is placed in an oven, the temperature is set to 80° C., and the drying time is 2 hours to obtain a dried carbon black / thermoplastic polyurethane spun film substrate.

[0021] Furthermore, a certain amount of anhydrous ethanol, 0.1-0.3 parts of carbon black particles, and 1-3 parts of a MXene / NMP suspension mixture are added to the S5 by mass to prepare a prefabricated substrate spinning membrane ultrasonic mixture.

[0022] Furthermore, in S6, the carbon black / thermoplastic polyurethane spinning film substrate dried in S4 is immersed in the prefabricated substrate spinning film ultrasonic mixed solution prepared in S5 for ultrasonic dispersion, and the ultrasonic time is 10 minutes at a power of 120W.

[0023] Furthermore, in S7, the carbon black / thermoplastic polyurethane / carbon black / MXene spinning film after ultrasound is taken out and placed in an oven at a temperature of 80° C. for 10 minutes for drying to obtain the textile flexible sensing material with high stretchability, wide detection range and high sensitivity.

[0024] Beneficial effects of the present invention:

[0025] The invention's preparation method involves adding carbon black particles to a solution of N,N-dimethylformamide and tetrahydrofuran before dissolving a thermoplastic polyurethane elastomer. This creates a first layer of a physical crosslinked network and a first layer of a conductive network for the spinning film, providing high stretchability and initial conductivity. MXene and carbon black particles in an ultrasonic solution are then used to construct a second layer of a physical and chemical crosslinked network and a second conductive network, generating chemical crosslinks and bonding that inhibit fiber slippage and enhance strain response sensitivity.

[0026] The carbon black particles of the present invention are uniformly embedded in the interior of thermoplastic polyurethane fibers through electrospinning to form a physical cross-linked network. The high specific surface area of ​​carbon black and the physical adsorption effect on the fibers disperse local stress and inhibit the expansion of microcracks, significantly improving the initial mechanical strength of the base film. MXene nanosheets are introduced into the fiber gaps through an ultrasonic penetration process, and the oxygen-containing functional groups on their surface form hydrogen bonds and chemical bonds with the polyurethane molecular chains to construct a chemical cross-linked network. During the stretching process, physical cross-linking dissipates energy through reversible fracture, and chemical cross-linking maintains structural integrity, achieving a synergistic improvement in stretchability and strength at the nanometer and micrometer scales. Compared with a single network structure, the material of the present invention avoids permanent damage during repeated stretching, breaking through the bottleneck of easy breakage of traditional flexible sensors.

[0027] The carbon black particles inside the electrospun fibers of the present invention form a tunneling conductive network. Small strains cause changes in the interparticle spacing, triggering a sudden change in the tunneling current to achieve a high-sensitivity response. MXene sheets form continuous conductive paths on the fiber surface through ultrasonic penetration. The sheet slip and contact area changes dominate the resistance response under large deformation. MXene and carbon black work synergistically to dynamically reconstruct the conductive network. At low strains, the point-like carbon black sensitive units provide high sensitivity. At high strains, the planar MXene network maintains conductive continuity. The graded response mechanism enables the material to exhibit nonlinear sensitivity improvement in the strain range, solving the problem of the narrow strain detection range of a single conductive filler.

[0028] During ultrasonic penetration, MXene sheets tightly adhere to the fiber surface. The high conductivity and sheet slip ability enable strain-induced resistance changes to be completed in milliseconds. The tunneling effect of carbon black particles amplifies the microstrain signal. The two work together to achieve instantaneous conversion from deformation to electrical signals. The physical cross-linked network reversibly breaks and reorganizes to dissipate energy, and the chemical cross-linked network maintains the stability of the main structure. The MXene sheets and fibers are mechanically interlocked to inhibit plastic deformation. The drying process strengthens the interfacial bonding force by removing the solvent. This design enables the material to maintain resistance response stability in 8000 seconds of continuous cycle testing, overcoming the problem of performance degradation caused by fatigue accumulation in flexible sensors.

[0029] The coupling of electrospinning and ultrasonic penetration technology breaks through the limitations of the complex multi-step preparation of traditional flexible sensors. Electrospinning controls the fiber orientation to form a porous interpenetrating structure, providing channels for the penetration of conductive fillers. Ultrasonic treatment enables the uniform loading of MXene carbon black in the fiber gaps, avoiding high-energy vacuum filtration or chemical deposition processes. The amount of MXene used in the material system is greatly reduced compared to traditional sensors. The low-cost characteristics of carbon black greatly reduce the cost of raw materials. The optimization of process parameters strengthens the interface bonding while shortening the preparation cycle, reducing the single-batch production time compared to similar technologies, providing a feasible path for large-scale applications.

[0030] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 Schematic diagram of the structure of the flexible sensing film of the present invention.

[0033] Figure 2 This is a flow chart for preparing the flexible sensing film of the present invention.

[0034] Figure 3 Scanning electron microscopy (SEM) images of the substrate film.

[0035] Figure 4 Fourier transform infrared spectra of the substrate film and carbon black / thermoplastic polyurethane / carbon black / MXene film.

[0036] Figure 5 These are stress-strain curves of the flexible sensing films prepared in Example 1, Example 2, Example 3, Example 4, Comparative Example 1, and Comparative Example 2.

[0037] Figure 6 The response speed and resolution of the sensing film prepared in Example 1 of the present invention.

[0038] Figure 7 The resistance change rate curve of the flexible sensing film material of the present invention after 5 consecutive cycles under different strains.

[0039] Figure 8 The resistance change rate curve of the sensing film prepared in Example 1 of the present invention at different rates under 50% strain.

[0040] Figure 9 The resistance change rate of the sensing film prepared in Example 1 of the present invention after cycling for 8000 seconds at a strain of 100%.

[0041] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0042] 1. Beaker; 2. Pipette; 3. N,N-dimethylformamide solution; 4. Tetrahydrofuran solution; 5. Carbon black particles; 6. Spoon; 7. N,N-dimethylformamide / tetrahydrofuran mixed solution; 8. Ultrasonic cell disruptor; 9. Thermoplastic polyurethane; 10. Rotor; 11. Magnetic stirrer; 12. Constant temperature and humidity chamber; 13. Carbon black / thermoplastic polyurethane spinning film; 14. Anhydrous ethanol solution; 15. MXene dispersion; 16. Carbon black / thermoplastic polyurethane / carbon black / MXene sensing film. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 any creative efforts shall fall within the scope of protection of the present invention.

[0044] Example 1

[0045] In this embodiment, the verification is further performed using mass units, which specifically includes the following steps:

[0046] S1: To a mixture of 15 g of N,N-dimethylformamide and 15 g of tetrahydrofuran, 0.3 g of carbon black particles were added, and the carbon black particles were ultrasonically dispersed at a power of 120 W for 30 minutes to obtain an N,N-dimethylformamide / tetrahydrofuran / carbon black mixed solution.

[0047] S2: Add 3 g of thermoplastic polyurethane to the mixed solution prepared in S1, heat to 50° C. and stir until completely dissolved to obtain a thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution.

[0048] S3: Pour the thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution prepared in S2 into the needle tube of the electrospinning equipment for spinning. The electrospinning parameters are controlled as follows: the screw position is 30 mm, the needle is 25° to the horizontal direction, the temperature is controlled at 35°C, the humidity is controlled at 40%, the voltage is 15KV, the moving platform moving speed is 2 mm / s, the moving swing is 4 mm, the main pump pushing speed is 0.0003 mm / min, and the roller speed is 80 rpm / min to obtain a carbon black / thermoplastic polyurethane spinning film substrate.

[0049] S4: The carbon black / thermoplastic polyurethane spun film substrate prepared in S3 is placed in an oven, the temperature is set to 80° C., and the drying time is 2 hours to obtain a dried carbon black / thermoplastic polyurethane spun film substrate.

[0050] S5: Add 50 ml of anhydrous ethanol, 0.6 g of carbon black particles, and 3 g of MXene / NMP suspension mixture into a beaker to prepare a prefabricated substrate spinning membrane ultrasonic mixture.

[0051] S6: The carbon black / thermoplastic polyurethane spinning film substrate dried in S4 is immersed in the prefabricated substrate spinning film ultrasonic mixed solution prepared in S5 for ultrasonic dispersion, and the ultrasonic time is 10 minutes at a power of 120W.

[0052] S7: The carbon black / thermoplastic polyurethane / carbon black / MXene spinning film after ultrasound is taken out and placed in an oven at 80°C for 10 minutes for drying to obtain the textile flexible sensing material with high stretchability, wide detection range and high sensitivity.

[0053] The carbon black / thermoplastic polyurethane / carbon black / MXene spun film obtained from the above raw materials and proportions was further tested for mechanical properties, including elongation at break and tensile strength. The specific results are as follows: Figure 3As shown, 0.3g of carbon black particles were added during the preparation of the base film, and 0.6g of carbon black particles were added during the subsequent ultrasonic mixing of the prefabricated base spinning membrane. The amount of MXene / NMP dispersion was 3g. The resulting carbon black / thermoplastic polyurethane / carbon black / MXene spinning membrane had an elongation at break of 298.8% and a tensile strength of 3758kPa. This is because carbon black particles were added during the preparation of the base film. Due to the physical adsorption properties of carbon black, the carbon black particles adsorbed the film fibers together, forming physical crosslinks and constructing the first layer of physical conductive network. Secondly, carbon black particles and MXene nanosheets were also added during the subsequent ultrasonic process. The carbon black particles and MXene adhered to the base fibers, and some of the carbon black particles entered the gaps between the fibers, once again physically crosslinking the fibers. The MXene nanosheets, rich in functional groups, formed chemical crosslinks with the base fibers, further strengthening the force of the spinning membrane.

[0054] Example 2

[0055] S1: 15 g of N,N-dimethylformamide solution and 15 g of tetrahydrofuran solution were mixed to obtain a 1:1 mixed solution of N,N-dimethylformamide and tetrahydrofuran.

[0056] S2: Pour 3 g of thermoplastic polyurethane into the mixed solution prepared in S1, heat to 55° C. and stir at 600 rpm for 8 hours until the thermoplastic polyurethane is completely dissolved, to obtain a thermoplastic polyurethane solution.

[0057] S3: Electrospin the 10% mass fraction of thermoplastic polyurethane solution prepared in S2 into a film using electrospinning technology. Wrap the drum with aluminum foil or silicone oil paper. Parameters: screw position 30 mm, needle angle 25° from horizontal, control temperature 35°C, control humidity 40%, voltage 15 kV, platform movement speed 2 mm / s, movement amplitude 4 mm, main pump feed rate 0.0003 mm / min, drum speed 80 rpm / min. This produces a thermoplastic polyurethane spun film substrate.

[0058] S4: taking out the thermoplastic polyurethane spun film substrate prepared in S3, placing it in an oven at 80° C. for 1 hour for drying, and obtaining a dried thermoplastic polyurethane spun film.

[0059] The mechanical properties of the thermoplastic polyurethane spun film obtained from the above raw materials and ratios were further tested. Figure 3 As shown in the figure, it can be seen that the elongation at break of the thermoplastic polyurethane spun film is 97.6% and the tensile strength is 1958 kPa.

[0060] Example 3

[0061] S1: (TPU / CB) 15 g of N,N-dimethylformamide solution and 15 g of tetrahydrofuran solution were mixed to obtain a 1:1 mixed solution of N,N-dimethylformamide and tetrahydrofuran.

[0062] S2: Pour 3 g of thermoplastic polyurethane into the mixed solution prepared in S1, heat to 55° C. and stir at 600 rpm for 8 hours until the thermoplastic polyurethane is completely dissolved, to obtain a thermoplastic polyurethane solution.

[0063] S3: Electrospin the 10% mass fraction of thermoplastic polyurethane solution prepared in S2 into a film using electrospinning technology. Wrap the drum with aluminum foil or silicone oil paper. Parameters: screw position 30 mm, needle angle 25° from horizontal, control temperature 35°C, control humidity 40%, voltage 15 kV, platform movement speed 2 mm / s, movement amplitude 4 mm, main pump feed rate 0.0003 mm / min, drum speed 80 rpm / min. This produces a thermoplastic polyurethane spun film substrate.

[0064] S4: The thermoplastic polyurethane spun film substrate prepared in S3 is taken out, placed in an oven at 80° C., and dried for 1 hour to obtain a dried thermoplastic polyurethane spun film substrate.

[0065] S5: Prepare an ultrasonic mixed solution, weigh 0.6 g of carbon black and 100 ml of anhydrous ethanol, and pour the carbon black particles into the anhydrous ethanol to obtain a 6 mg / ml ultrasonic carbon black mixed solution.

[0066] S6: Immerse the thermoplastic polyurethane spun film substrate prepared in S4 in the ultrasonic mixture prepared in S5 and place it in an ultrasonic machine. Set the parameters to 120 W power, 2 seconds on time, 4 seconds off time, and a total ultrasonic duration of 10 minutes to obtain a thermoplastic polyurethane / carbon black spun film.

[0067] S7: The spun film after the ultrasonic treatment in S6 is removed and placed in an oven to dry out the solvent. The oven temperature is set to 80° C. and the drying time is set to 20 minutes to produce a thermoplastic polyurethane / carbon black spun film.

[0068] In this embodiment, the mechanical properties of the thermoplastic polyurethane / carbon black spun film obtained from the above raw materials and ratios of this embodiment were further tested, and the specific results are as follows: Figure 3As shown in the figure, the elongation at break is 145% and the tensile strength is 1141 kPa. Compared with Example 2, the mechanical properties of the polyurethane / carbon black spun film are significantly improved. This is attributed to the addition of carbon black particles to the ultrasonic mixing liquid. The uniform dispersion of carbon black in the thermoplastic polyurethane matrix and the hydrogen bonding between the carbon black and the thermoplastic polyurethane fiber membrane are the main reasons for the significant improvement in the mechanical properties of the thermoplastic polyurethane / carbon black spun film.

[0069] Example 4

[0070] S1: 15 g of N,N-dimethylformamide solution and 15 g of tetrahydrofuran solution were mixed to obtain a 1:1 mixed solution of N,N-dimethylformamide and tetrahydrofuran.

[0071] S2: Pour 3 g of thermoplastic polyurethane into the mixed solution prepared in S1, heat to 55° C. and stir at 600 rpm for 8 hours until the thermoplastic polyurethane is completely dissolved, to obtain a thermoplastic polyurethane solution.

[0072] S3: Electrospin the 10% mass fraction of thermoplastic polyurethane solution prepared in S2 into a film using electrospinning technology. Wrap the drum with aluminum foil or silicone oil paper. Parameters: screw position 30 mm, needle angle 25° from horizontal, control temperature 35°C, control humidity 40%, voltage 15 kV, platform movement speed 2 mm / s, movement amplitude 4 mm, main pump feed rate 0.0003 mm / min, drum speed 80 rpm / min. This produces a thermoplastic polyurethane spun film substrate.

[0073] S4: taking out the thermoplastic polyurethane spun film substrate prepared in S3, placing it in an oven at 80° C. for 1 hour for drying, and obtaining a dried thermoplastic polyurethane spun film.

[0074] S5: Prepare an ultrasonic mixed solution by weighing 0.3 g of MXene / NMP dispersion and 100 ml of anhydrous ethanol, and pouring the MXene / NMP dispersion into the anhydrous ethanol to obtain an ultrasonic mixed solution.

[0075] S6: Immerse the TPU spun film substrate prepared in S4 in the ultrasonic mixture prepared in S5 and place it in an ultrasonic machine. Set the ultrasonic parameters to 120 W power, 2 seconds on time, 4 seconds off time, and a total ultrasonic duration of 10 minutes to obtain a TPU / MXene spun film.

[0076] S7: Remove the spun film from S6 after ultrasonic treatment and place it in an oven to dry out the solvent. Set the oven temperature to 80°C and dry for 20 minutes to produce a thermoplastic polyurethane / MXene spun film.

[0077] In this embodiment, the mechanical properties of the thermoplastic polyurethane / carbon black spun film obtained from the above raw materials and ratios of this embodiment were further tested, and the specific results are as follows: Figure 3 As shown in the figure, its elongation at break is 143.6% and its tensile strength is 1494 kPa. Compared with Example 2, the mechanical properties of the thermoplastic polyurethane / MXene spun film are also significantly improved. This is attributed to the uniform dispersion of MXene nanosheets in the thermoplastic polyurethane matrix and the hydrogen bonding between the MXene nanosheets and the thermoplastic polyurethane fiber membrane, which are the main reasons for the significant improvement in the mechanical properties of the thermoplastic polyurethane / MXene spun film.

[0078] At the same time, combined with the comparison between Example 2 and Example 3, it can be seen that Example 3 and Example 4 improve the mechanical properties of the spun film by adding carbon black particles or MXene nanosheets. Combined with Example 2, Example 3 and Example 4, the addition of carbon black particles and MXene can improve the mechanical properties of the spun film to varying degrees.

[0079] Comparative Example 1

[0080] S1: To a mixture of 15 g of N,N-dimethylformamide and 15 g of tetrahydrofuran, 0.3 g of carbon black particles were added, and the carbon black particles were ultrasonically dispersed at a power of 120 W for 30 minutes to obtain an N,N-dimethylformamide / tetrahydrofuran / carbon black mixed solution.

[0081] S2: Add 3 g of thermoplastic polyurethane to the mixed solution prepared in S1, heat to 50° C. and stir until completely dissolved to obtain a thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution.

[0082] S3: Pour the thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution prepared in S2 into the needle tube of the electrospinning equipment for spinning. The electrospinning parameters are controlled as follows: the screw position is 30 mm, the needle is 25° to the horizontal direction, the temperature is controlled at 35°C, the humidity is controlled at 40%, the voltage is 15KV, the moving platform moving speed is 2 mm / s, the moving swing is 4 mm, the main pump pushing speed is 0.0003 mm / min, and the roller speed is 80 rpm / min to obtain a carbon black / thermoplastic polyurethane spinning film substrate.

[0083] S4: The carbon black / thermoplastic polyurethane spun film substrate prepared in S3 is placed in an oven, the temperature is set to 80° C., and the drying time is 2 hours to obtain a dried carbon black / thermoplastic polyurethane spun film substrate.

[0084] S5: Add 50 ml of anhydrous ethanol and 0.6 g of carbon black particles into a beaker to prepare a prefabricated substrate spinning membrane ultrasonic mixed solution.

[0085] S6: The carbon black / thermoplastic polyurethane spinning film substrate dried in S4 is immersed in the prefabricated substrate spinning film ultrasonic mixed solution prepared in S5 for ultrasonic dispersion, and the ultrasonic time is 10 minutes at a power of 120W.

[0086] S7: The carbon black / thermoplastic polyurethane / carbon black spun film after ultrasound was taken out and placed in an oven at 80° C. for 10 minutes for drying to obtain a carbon black / thermoplastic polyurethane / carbon black spun film.

[0087] The mechanical properties of the thermoplastic polyurethane / carbon black spun film obtained from the above raw materials and ratios in Comparative Example 1 were further tested. The specific results are as follows: Figure 3 As shown in the figure, it can be seen that its elongation at break is 170% and its tensile strength is 1061.6kPa.

[0088] Comparative Example 2

[0089] S1: To a mixture of 15 g of N,N-dimethylformamide and 15 g of tetrahydrofuran, 0.3 g of carbon black particles were added, and the carbon black particles were ultrasonically dispersed at a power of 120 W for 30 minutes to obtain an N,N-dimethylformamide / tetrahydrofuran / carbon black mixed solution.

[0090] S2: Add 3 g of thermoplastic polyurethane to the mixed solution prepared in S1, heat to 50° C. and stir until completely dissolved to obtain a thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution.

[0091] S3: Pour the thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution prepared in S2 into the needle tube of the electrospinning equipment for spinning. The electrospinning parameters are controlled as follows: the screw position is 30 mm, the needle is 25° to the horizontal direction, the temperature is controlled at 35°C, the humidity is controlled at 40%, the voltage is 15KV, the moving platform moving speed is 2 mm / s, the moving swing is 4 mm, the main pump pushing speed is 0.0003 mm / min, and the roller speed is 80 rpm / min to obtain a carbon black / thermoplastic polyurethane spinning film substrate.

[0092] S4: The carbon black / thermoplastic polyurethane spun film substrate prepared in S3 is placed in an oven, the temperature is set to 80° C., and the drying time is 2 hours to obtain a dried carbon black / thermoplastic polyurethane spun film substrate.

[0093] S5: Add 50 ml of anhydrous ethanol and 3 g of MXene / NMP suspension mixture into a beaker to prepare a prefabricated substrate spinning membrane ultrasonic mixture.

[0094] S6: The carbon black / thermoplastic polyurethane spinning film substrate dried in S4 is immersed in the prefabricated substrate spinning film ultrasonic mixed solution prepared in S5 for ultrasonic dispersion, and the ultrasonic time is 10 minutes at a power of 120W.

[0095] S7: The carbon black / thermoplastic polyurethane / MXene spun film after ultrasound was taken out and placed in an oven at 80°C for 10 minutes for drying to obtain a carbon black / thermoplastic polyurethane / MXene spun film.

[0096] The mechanical properties of the thermoplastic polyurethane / carbon black spun film obtained from the above raw materials and ratios in Comparative Example 2 were further tested. The specific results are as follows: Figure 3 As shown in the figure, it can be seen that its elongation at break is 163.9% and its tensile strength is 1957.4kPa. Combined with the comparative example 1, when carbon black particles are added in comparative example 1, the elongation at break of the spun film prepared is 170% and the tensile strength is 1061.6%. When MXene nanosheets are added in comparative example 2, the elongation at break is 163.9% and the tensile strength is 1957.4kPa, which shows that the different conductive fillers added have an effect on the mechanical properties of the film. Moreover, carbon black particles can form physical and chemical crosslinks with the matrix fibers, while MXene nanosheets only undergo chemical crosslinking with the matrix fibers. Compared with comparative example 1, it can be seen that when carbon black particles and MXene nanosheets are introduced as conductive fillers at the same time, the mechanical properties of the spun film are the best, with an elongation at break of 298.7% and a tensile strength of 3758kPa. Compared with the textile flexible sensors in the existing technology, it has excellent high stretchability and high sensitivity flexible strain sensors, strong comprehensive performance, simple manufacturing scheme and low economic cost; and in the specific time of electrical signal detection for the human body, it can show different signals, indicating that the present invention has application potential in the fields of human motion monitoring and health monitoring management.

[0097] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A flexible sensing material with high stretchability, wide detection range and high sensitivity, characterized in that: Includes the following structures: First layer physical cross-linking network and conductive network: Carbon black particles are evenly dispersed in thermoplastic polyurethane fibers through an electrospinning process. The carbon black particles form a physical cross-linking network with the thermoplastic polyurethane molecular chains through physical adsorption. At the same time, the carbon black particles form a continuous first layer of conductive network through the tunneling effect. The second layer of physical and chemical cross-linking network and composite conductive network: carbon black particles and MXene nanosheets are loaded into the gaps of thermoplastic polyurethane fibers through ultrasonic treatment, where the carbon black particles further enhance the fiber cross-linking density through physical adsorption, and the MXene nanosheets form chemical bonds with thermoplastic polyurethane molecular chains through surface functional groups to jointly construct the second layer of physical and chemical cross-linking network; MXene and carbon black synergistically form the second layer of composite conductive network.

2. The flexible sensing material according to claim 1, wherein: The amount of carbon black particles added to the first layer is 0.1-0.3 times the mass of the thermoplastic polyurethane; The amount of carbon black particles added in the second layer is 0.1-0.3 times the mass of the thermoplastic polyurethane, and the amount of MXene added is 1-3 times the mass of the thermoplastic polyurethane.

3. A method for preparing the flexible sensing material according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1: preparing a mixed solution of N,N-dimethylformamide / tetrahydrofuran / carbon black; S2: adding thermoplastic polyurethane to the mixed solution of step S1 after ultrasonic treatment, heating and stirring to dissolve, to prepare a thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution; S3: pouring the dissolved solution in step S2 into a needle tube for electrospinning to obtain a carbon black / thermoplastic polyurethane spinning film substrate; S4: placing the spun film in an oven for drying to obtain a dried carbon black / thermoplastic polyurethane spun film substrate; S5: Preparation of prefabricated substrate spinning membrane ultrasonic mixture: anhydrous ethanol / carbon black / MXene mixed solution; S6: immersing the spun film obtained in step S4 into the prefabricated base spinning film ultrasonic mixed solution obtained in S5 for ultrasonic treatment to obtain a carbon black / thermoplastic polyurethane / carbon black / MXene spun film; S7: The carbon black / thermoplastic polyurethane / carbon black / MXene spun film of step S6 is taken out and placed in an oven for drying to obtain the textile flexible sensing material with high stretchability, wide detection range and high sensitivity.

4. The preparation method according to claim 3, wherein: In S1, 0.1-0.3 parts by mass of carbon black particles are added to a mixture of N,N-dimethylformamide and tetrahydrofuran, and the carbon black particles are ultrasonically dispersed at a power of 120 W for 30 minutes to obtain an N,N-dimethylformamide / tetrahydrofuran / carbon black mixed solution.

5. The preparation method according to claim 3, wherein: In S2, 1-3 parts by mass of thermoplastic polyurethane are added to the mixed solution prepared in S1, and the mixture is heated to 50° C. and stirred until completely dissolved to obtain a thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution.

6. The preparation method according to claim 3, wherein: In S3, the thermoplastic polyurethane / carbon black / NN dimethylformamide / tetrahydrofuran mixed solution prepared in S2 is poured into the needle tube of the electrospinning equipment for spinning, and the electrospinning parameters are controlled as follows: the screw position is 30 mm, the needle head is 25° to the horizontal direction, the temperature is controlled at 35°C, the humidity is controlled at 40%, the voltage is 15KV, the moving platform moving speed is 2 mm / s, the moving swing is 4 mm, the main pump pushing speed is 0.0003 mm / min, and the roller speed is 80 rpm / min to obtain a carbon black / thermoplastic polyurethane spinning film substrate.

7. The preparation method according to claim 3, wherein: In the above S4, the carbon black / thermoplastic polyurethane spun film substrate prepared in S3 is placed in an oven, the temperature is set to 80° C., and the drying time is 2 hours to obtain a dried carbon black / thermoplastic polyurethane spun film substrate.

8. The preparation method according to claim 3, wherein: According to mass, anhydrous ethanol, 0.1-0.3 parts of carbon black particles, and 1-3 parts of MXene / NMP suspension mixture are added to the S5 to prepare a prefabricated substrate spinning membrane ultrasonic mixture.

9. The preparation method according to claim 3, wherein: In the above-mentioned S6, the carbon black / thermoplastic polyurethane spinning film substrate dried in S4 is immersed in the prefabricated substrate spinning film ultrasonic mixed solution prepared in S5 for ultrasonic dispersion, and the ultrasonic time is 10 minutes at a power of 120W.

10. The preparation method according to claim 3, wherein: In the S7, the carbon black / thermoplastic polyurethane / carbon black / MXene spinning film after ultrasound is taken out and placed in an oven at 80° C. for 10 minutes for drying to obtain the textile flexible sensing material with high stretchability, wide detection range and high sensitivity.

11. An application of the flexible sensing material according to claim 1, characterized in that: Used to monitor human movement, including real-time detection of facial muscle activity, wrist flexion and finger bending.

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