Multi-response sodium alginate / Ti < 3 > C < 2 > T < x > MXene / PVDF composite sensing device and preparation method

Abstract

The invention discloses a multi-response sodium alginate / Ti < 3 > C < 2 > T < x > MXene / PVDF composite sensing device and a preparation method. The sensing device comprises a porous sponge layer, an electrode layer, a PVDF fiber membrane layer, an electrode layer and a porous sponge layer which are sequentially distributed from top to bottom. The porous sponge is prepared from a sodium alginate / polyvinyl alcohol matrix, Ti < 3 > C < 2 > T < x > MXene and magnetic particles through crosslinking and directional freeze drying. The PVDF fiber membrane is prepared by adopting an electrostatic spinning process. Sodium alginate / polyvinyl alcohol is used as a base material, Ti3C2Tx MXene and magnetic particles are added, porous sponge with magnetic, force and heat multi-response characteristics and higher flexibility is prepared through a biological crosslinking and directional freezing technology, and a PVDF fiber membrane prepared through an electrostatic spinning technology is introduced to form a multi-layer composite sensing device. The multi-response sensing device is superior to a traditional single-response device in the aspects of sensitivity, flexibility and stability, has wide application potential and is particularly suitable for high-precision and multi-environment detection requirement scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible wearable sensors, and specifically to a multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device and a preparation method thereof. Background Art

[0002] In the current field of human-computer interaction, the application of sensors is becoming increasingly important, especially for scenarios that require high sensitivity and rapid response. Traditional sensor technologies have certain limitations in detecting multiple physical signals (such as force, magnetism, heat), and cannot fully meet the real-time response requirements in complex human-computer interaction environments. In addition, the rigid structure of traditional materials makes it difficult for them to flexibly adapt to complex curved surfaces or bending structures, restricting their application in flexible wearable devices.

[0003] The applicant previously disclosed a sodium alginate-polyvinyl alcohol force / magnetic sensor material for wearable electronics and a preparation method thereof (application publication number CN117024894A). This force / magnetic sensing material is a non-oriented porous sponge material with a tensile strain limit of 34.6%, does not have thermal response characteristics, and its electrical properties and flexibility need to be improved. Summary of the Invention

[0004] The present invention aims to provide a multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device and a preparation method thereof, which not only have good flexibility and conformability on complex-shaped and curved surfaces, but also have excellent electrical conductivity and thermal response performance, and can adapt to a variety of complex human-computer interaction scenarios.

[0005] To solve the above technical problems, the specific solution adopted by the present invention is as follows: A multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, including a PVDF fiber membrane layer in the middle, porous sponge layers on both sides of the PVDF fiber membrane layer, and an electrode layer between the PVDF fiber membrane layer and the porous sponge layers. The electrode layer is distributed on the porous sponge layers, and the porous sponge layers and the PVDF fiber membrane layer are formed by hot pressing and bonding.

[0006] The PVDF fiber membrane layer is formed by interweaving fiber filaments with a nanoscale diameter. The porous sponge layer includes a composite sol matrix and Ti3C2T x Mxene and magnetic particles dispersed in the composite sol matrix. There are uneven contact surfaces between the PVDF fiber membrane layer and the electrode layer and between the electrode layer and the porous sponge layer, and the uneven contact surfaces are formed during the hot pressing and bonding process due to the pore structure of the PVDF fiber membrane layer.

[0007] Preferably, the thickness of the PVDF fiber membrane layer is 9-12 μm.

[0008] A multi-responsive sodium alginate / Ti3C2T x The preparation method of the MXene / PVDF composite sensor device comprises mixing N, N-dimethylformamide, acetone and PVDF particles to obtain an electrospinning solution, spraying the electrospinning solution onto a collector through a syringe to form a PVDF fiber membrane layer; placing the PVDF fiber membrane layer between two porous sponge layers with electrode layers on opposite sides, and then combining the PVDF fiber membrane layer and the porous sponge layer by hot pressing.

[0009] Preferably, the porous sponge layer is prepared by:

[0010] Sodium alginate and polyvinyl alcohol were added into distilled water respectively and stirred evenly to obtain a composite sol matrix. x MXene and magnetic particles are dissolved in a composite sol matrix, and then glycerol and calcium chloride are added and stirred evenly before being poured into a mold; the mold is first placed in liquid nitrogen for directionally freezing, and after directionally freezing and forming, the mold is placed in a freeze dryer and freeze-dried to obtain a porous sponge layer.

[0011] Preferably, the mass ratio of sodium alginate to polyvinyl alcohol is 1:1-4; Ti3C2T x The volume ratio of MXene to the composite sol matrix is 0.5-3:50.

[0012] Preferably, the amount of liquid nitrogen added is 1 / 3-2 / 3 of the mold height; the temperature in the freeze dryer is -50-70°C, and the vacuum degree is below 10Pa.

[0013] Preferably, the volume ratio of N,N-dimethylformamide to acetone is 6:3-5.

[0014] Preferably, the distance between the syringe and the collector is 5-25 cm, the voltage range is 10-25 kV, the propulsion speed is 0.1-2 ml / h, and the spinning time is 8-16 h.

[0015] Preferably, the hot pressing temperature is 50-100° C., and the hot pressing time is 3-10 minutes.

[0016] Preferably, the method for preparing magnetic particles comprises the following steps:

[0017] 1) Mix carbonyl iron powder, magnetic Fe3O4 particles, and sodium chloride, add them to a gelatin aqueous solution and perform ultrasonic oscillation. Then, use a permanent magnet to separate the coated magnetic particles, wash the magnetic particles with deionized water, and then dry them.

[0018] 2), adding multi-walled carbon nanotubes to a mixed acid made of nitric acid and sulfuric acid, and obtaining an acidified multi-walled carbon nanotube solution after ultrasonic irradiation;

[0019] 3), adding the gelatin-coated magnetic particles obtained in step 1) to the acidified multi-walled carbon nanotube solution prepared in step 2) for ultrasonic oscillation, so that the multi-walled carbon nanotubes are coated on the surface of the gelatin-coated magnetic particles, then separating the magnetic particles coated with multi-walled carbon nanotubes with a permanent magnet, and then washing and drying with deionized water to obtain magnetic particles.

[0020] The advantages of this invention patent are as follows:

[0021] 1. In the present invention, a porous sponge layer is prepared by the directional freezing technique. First, rapid freezing is achieved through the quick-freezing effect of liquid nitrogen to form an ice crystal structure along the cooling direction. Then, an oriented pore structure is formed in the drying stage, making the pore structure in the porous sponge layer arranged orderly along a certain direction, so that the pores in the porous structure are regularized and homogenized. Furthermore, the mechanical properties of the prepared material are better, and it can better adapt to different shaped and curved surfaces, especially suitable for intelligent wearable devices and curved surface sensors, improving the conformability and comfort of the sensors. At the same time, due to the high orientation of the porous sponge layer, uniform electrical property changes can be generated during the deformation process, thus improving the linearity of the sensor response.

[0022] 2. Ti3C2T x Mxene is added to the porous sponge layer in the present invention. Ti3C2T x MXene has abundant surface active sites, and crosslinking is achieved through the action of Ca 2+ , that is, Ca 2+ interacts with the hydroxyl groups in the polyvinyl alcohol molecules and the surface active sites of MXene, making MXene firmly adhere to the pore walls. This crosslinking mechanism not only improves the dispersibility and stability of Ti3C2T x MXene in the porous sponge layer, but also because Ti3C2T x MXene material itself has relatively high interfacial thermal resistance and relatively low planar thermal conductivity. Therefore, when Ti3C2T x MXene constructs a three-dimensional porous network, good thermoelectric properties will be generated, which endows the sensor with excellent thermal response ability and provides superior performance support for multi-response sensors. Furthermore, the sensor device prepared in the present invention integrates multiple response characteristics of force, magnetism, and heat, can generate corresponding signals under various physical stimuli, and is suitable for the detection requirements of multi-dimensional information in complex human-computer interaction scenarios.

[0023] 3. The PVDF fiber membrane layer in the present invention is prepared by electrospinning process, forming a multi-porous structure intertwined by nanofibers with a diameter in the nanometer range. On one hand, the good internal pore structure of the PVDF nanofiber membrane enables the formation of concave and convex structures on the surface pores of the PVDF fiber membrane layer during the hot pressing process of the porous sponge layer and the PVDF fiber membrane layer, causing deformation on both the overall electrode layer and the inner side of the porous sponge layer, resulting in concave and convex contact surfaces rather than flat contact surfaces. Thus, the contact area between the electrode layer and the PVDF fiber membrane layer and between the electrode layer and the porous sponge layer increases, further enabling the sample to obtain more excellent electrical properties. On the other hand, its thickness is only about 10 μm, and the thinner nanofiber membrane is more prone to bending deformation, showing better superiority in terms of conforming to the human body and comfort.

[0024] 4. In the present invention, sodium alginate biobased material is selected, which reduces the impact on the environment and simultaneously improves the biocompatibility of the material, making it more suitable for wearable devices that come into direct contact with the human body. Brief Description of the Drawings

[0025] Figure 1 It is an exploded structural schematic diagram of the multi-responsive sensor device prepared in Example 1 of the present invention;

[0026] Figure 2 It is a preparation flow chart of the multi-responsive sensor device prepared in Example 1 of the present invention;

[0027] Figure 3 It is a cross-sectional scanning electron microscope (SEM) image of the porous sponge structure in the multi-responsive sensor device prepared in Example 1 of the present invention;

[0028] Figure 4 It is a scanning electron microscope (SEM) image of the PVDF nanofiber membrane structure prepared in Example 1 of the present invention;

[0029] Figure 5 It is a change curve of the tensile mechanical properties of the multi-responsive sensor device prepared in Example 1 of the present invention;

[0030] Figure 6 It is a change curve of the compressive mechanical properties of the multi-responsive sensor device prepared in Example 1 of the present invention;

[0031] Figure 7 It is a change curve of the electrical response performance of the porous sponge structure in the multi-responsive sensor device prepared in Example 1 of the present invention under different temperature field excitations.

[0032] Figure 8 It is a change curve of the electrical response performance of the multi-responsive sensor device prepared in Example 1 of the present invention under different pressure excitations;

[0033] Figure 9Curves of the electrical response performance changes of the multi-responsive sensor device prepared in Example 1 of the present invention under different magnetic field excitations;

[0034] Figure 10 Scanning electron microscope (SEM) image of the PVDF nanofiber membrane structure prepared in Example 2 of the present invention;

[0035] Figure 11 Scanning electron microscope (SEM) image of the PVDF nanofiber membrane structure prepared in Example 3 of the present invention. Detailed implementation manners

[0036] As Figure 1 shown, a multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device of the present invention includes a porous sponge layer, an electrode layer, a PVDF fiber membrane layer, an electrode layer, and a porous sponge layer which are distributed in sequence from top to bottom. The porous sponge is formed by cross-linking and directional freeze-drying of a sodium alginate / polyvinyl alcohol matrix, Ti3C2T x MXene, and magnetic microparticles. The PVDF fiber membrane is prepared by an electrospinning process. The present invention uses sodium alginate / polyvinyl alcohol as the matrix material, adds Ti3C2T x MXene and magnetic microparticles through a biological cross-linking and directional freezing process to obtain a porous sponge with magnetic, force, and thermal multi-responsive characteristics and higher flexibility, and introduces a PVDF fiber membrane prepared by an electrospinning process to form a multi-layer composite sensor device. This multi-responsive sensor device is superior to traditional single-responsive devices in terms of sensitivity, flexibility, and stability, and has broad application potential, especially suitable for scenarios with high-precision and multi-environment detection requirements.

[0037] As Figure 2 shown, the preparation method of the above-mentioned multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device includes the following steps:

[0038] (1) Preparation of the composite sol matrix

[0039] Add sodium alginate and polyvinyl alcohol into distilled water respectively, stir at a set temperature until the solution is uniform and particle-free, and then mix and stir the two to generate a uniform sol-like matrix solution to obtain the composite sol matrix.

[0040] The degree of alcoholysis of polyvinyl alcohol is 87%-95%. The range of the mass ratio of sodium alginate to polyvinyl alcohol is 1:1-4. The stirring speed is 350 r / min to 450 r / min, the stirring time is 20 min to 30 min, and the stirring temperature is 55°C to 65°C.

[0041] (2) Cross-linking reaction

[0042] Add Ti3C2T x MXene to the composite sol matrix and stir evenly. Then add the double-dispersed magnetic particles to the composite sol matrix and stir rapidly until the magnetic particles are completely dissolved in the composite sol matrix. Subsequently, add a certain amount of glycerol and calcium chloride solution to the composite sol matrix and mix evenly.

[0043] Ti3C2T x The volume ratio of MXene to the composite sol matrix in the first step ranges from 0.5 to 3:50.

[0044] The magnetic particles are prepared by a method including the following steps:

[0045] 1) Weigh a certain amount of carbonyl iron powder, magnetic Fe3O4 particles, and sodium chloride, mix them and add them to the gelatin aqueous solution, and perform ultrasonic oscillation to make the gelatin evenly cover the surfaces of the carbonyl iron powder and Fe3O4 powder. Then use a permanent magnet to separate the coated magnetic particles, then wash the particles with deionized water, and then dry them; the mass-volume concentration of the gelatin aqueous solution is 0.1 g / mL; the mass ratio of the carbonyl iron powder, magnetic Fe3O4, and sodium chloride is 4:0.5:0.2; the mass ratio of the mass of the carbonyl iron powder to the mass of gelatin in the gelatin aqueous solution is 4:2.5; the average particle size of the carbonyl iron powder is 3.5 μm, and the density is 7.9 g / cm3; the average particle size of the magnetic Fe3O4 is 20 nm;

[0046] 2) At a temperature of 55°C to 65°C, add multi-walled carbon nanotubes to the mixed acid made of nitric acid and sulfuric acid with a molar ratio of 3:1, and irradiate with ultrasonic waves for 12 h to obtain an acidified multi-walled carbon nanotube solution;

[0047] 3) Add the gelatin-coated magnetic particles obtained in step 1) to the acidified multi-walled carbon nanotube solution prepared in step 2) and perform ultrasonic oscillation to make the multi-walled carbon nanotubes cover the surface of the gelatin-coated magnetic particles. Then use a permanent magnet to separate the multi-walled carbon nanotube-coated magnetic particles, and then wash and dry them with deionized water to obtain the product.

[0048] (3) Directional freezing and drying

[0049] Pour the evenly mixed composite sol into a polytetrafluoroethylene mold and place it in liquid nitrogen for rapid directional freezing. After the sample is completely frozen and formed, transfer it to a pre-frozen freeze dryer, cover it with a freeze-drying cover, turn on the vacuum pump for drying treatment, and finally demold it into a porous sponge, and evenly disperse the conductive silver paste on one side of the porous sponge.

[0050] When using liquid nitrogen for directional freezing treatment, goggles and protective gloves must be worn. The amount of liquid nitrogen added should be 1 / 3 to 2 / 3 of the total height of the mold, and the liquid nitrogen treatment time should be no less than 30 seconds.

[0051] During freeze drying, the freezing temperature is -50 to 70°C, and the vacuum degree is ensured to be below 10Pa during drying to obtain an ideal oriented porous sponge structure.

[0052] (4) Preparation of polyvinylidene fluoride (PVDF) fiber membrane

[0053] A certain proportion of N, N-dimethylformamide and acetone are mixed, and then PVDF particles are added to the mixed solution and stirred until completely dissolved to obtain an electrospinning solution. Finally, the electrospinning solution is sprayed onto a collector through a syringe to form a fiber membrane.

[0054] The ratio of N,N-dimethylformamide to acetone is in the range of 6:3-5. The distance between the syringe and the collector is 5 cm to 25 cm. The voltage range is 10 kV to 25 kV. The propulsion speed is 0.1 to 2 ml / h. The spinning time is 8 to 16 hours.

[0055] (5) Hot pressing

[0056] The PVDF fiber membrane is placed between two porous sponges and hot-pressed at a certain temperature using a hot press.

[0057] The hot pressing temperature is 50°C-100°C, and the hot pressing time is 3min-10min.

[0058] The preparation method of the present invention is further described below through a number of examples:

[0059] Example 1

[0060] (1) Preparation of composite sol matrix: 0.5 g of sodium alginate and 2 g of polyvinyl alcohol were added to 25 ml of distilled water, respectively, and stirred at 60°C and 80°C, respectively, until the solution was uniform and free of particles. The two were then mixed and stirred to form a uniform sol-like matrix solution to obtain a composite sol matrix.

[0061] (2) Cross-linking reaction: 1.5 ml Ti3C2T x MXene was added to the composite sol matrix and stirred evenly. Then, 3g of bidisperse magnetic particles were added to the composite sol matrix and stirred rapidly until the magnetic particles were completely dissolved. Subsequently, 2ml of glycerol and 10ml of 1% CaCl2 solution were added to the composite sol matrix and mixed evenly.

[0062] (3) Directional freezing and drying: Pour the mixed composite sol into a polytetrafluoroethylene mold and place it in liquid nitrogen for rapid direction freezing. The liquid nitrogen is added to a height of 2 / 3 of the total height of the mold and the processing time is 30 seconds. After the sample is completely frozen and formed, it is transferred to a pre-frozen freeze dryer and covered with a freeze drying cover. The vacuum pump is turned on and the sample is dried for 12 hours. Finally, the sample is demolded into a porous sponge and the conductive silver paste is evenly dispersed on one side of the porous sponge.

[0063] (4) Preparation of PVDF fiber membrane: 12 ml of N, N-dimethylformamide and 8 ml of acetone were mixed, and then 3 g of PVDF particles were added to the mixed solution and stirred until completely dissolved to obtain an electrospinning solution. Finally, the electrospinning solution was sprayed onto a collector through a syringe to form a fiber membrane.

[0064] (5) Hot pressing: Place the PVDF fiber membrane between two porous sponges and use a hot press to press it at 80°C for 5 minutes to form it.

[0065] The cross-sectional scanning electron microscope (SEM) image of the porous sponge structure in the multi-response sensor device prepared in Experimental Example 1 is shown in FIG. Figure 3 shown.

[0066] Depend on Figure 3 It can be seen that the pores in the porous sponge are uniform and regular, the pore wall thickness is uniform and moderate, and it has good orientation and uniform pore distribution. x MXene is evenly dispersed on the pore wall structure.

[0067] Scanning electron microscope (SEM) image of the PVDF nanofiber membrane structure prepared in Example 1; Figure 4 It can be seen that these fibers present a cross-layered three-dimensional network. The nanofiber membrane structure is obtained by compounding a spun-like structure with an average diameter of about 100.8 mm. The internal structure has a large number of pores, which provides excellent interface conformal contact conditions for the upper and lower sponge electrodes.

[0068] The multi-response sensor device prepared in Example 1 was subjected to tensile mechanical performance testing. The results are as follows: Figure 5 As shown. Figure 5 It can be seen that the sample begins to break when the strain reaches 50.5%, and completely breaks when the strain reaches 68.7%, showing good ductility and toughness.

[0069] The multi-response sensor device prepared in Example 1 was subjected to compression mechanical performance test. The results are as follows: Figure 6 As shown. Figure 6 It can be seen that the sample can achieve a deformation of up to 80% during the compression process, and the maximum elastic modulus is 1.37 MPa.

[0070] The electrical response performance of the porous sponge structure in the multi-responsive sensor device prepared in Example 1 was tested under different temperature field excitations, and the measured thermoelectric voltage-temperature gradient curve is as Figure 7 shown. From Figure 7 it can be seen that the calculated Seebeck coefficient S T value is -4.998 μV / K -1 , which is basically consistent with that of a single Ti3C2T x thin film S T value, further proving the formation of a highly continuous Ti3C2T x MXene network within the porous structure. At the same time, within a relatively wide temperature range, the S T value shows a good linear relationship.

[0071] The electrical response performance of the multi-responsive sensor device prepared in Example 1 was tested under different pressure excitations, and the measured resistance change rate-pressure curve is as Figure 8 shown. From Figure 8 it can be seen that the resistance change rate of the sensor is within the ranges of 0 - 56 kPa -1 and 56 - 100 kPa -1 , and the pressure response sensitivity coefficients are -0.98 kPa -1 and -1.65 kPa -1 respectively. As the applied pressure increases, the sensor material is significantly compressed, the pore structure shrinks, causing an increasing resistance change. When the pressure reaches around 56 kPa -1 , the sensor is further compressed, and the good pore structure of the PVDF fiber membrane enables the contact area between the two ends of the sponge structure to continuously increase, resulting in a more significant resistance change.

[0072] The electrical response performance of the multi-responsive sensor device prepared in Example 1 was tested under different magnetic field excitations, and the measured resistance change rate-magnetic induction intensity curve is as Figure 9 shown. From Figure 9 it can be seen that the resistance change rate of the sensor is within the ranges of 0 - 175 mT and 175 - 300 mT, and the magnetic response sensitivity coefficients are -0.55 T -1 and -0.03 T -1 respectively. As the magnetic induction intensity increases, the sensor undergoes obvious deformation, causing an increasing resistance change. When the magnetic induction intensity reaches around 175 mT, the sensor no longer undergoes obvious deformation, and the resistance change basically reaches stability.

[0073] Example 2

[0074] A multi-responsive sodium alginate / Ti3C2T of this example xPreparation method of MXene / PVDF composite sensor device, which is basically the same as the preparation process of Example 1, except that: in step (2), 1 ml of Ti3C2T x MXene is added to the composite sol matrix.

[0075] The cross-sectional scanning electron microscope (SEM) image of the porous sponge structure prepared in Experimental Example 2 is as Figure 10 shown.

[0076] Example 3

[0077] A preparation method of a multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device in this example is basically the same as the preparation process of Example 1, except that: in step (2), 2 ml of Ti3C2T x MXene is added to the composite sol matrix.

[0078] The cross-sectional scanning electron microscope (SEM) image of the porous sponge structure prepared in Experimental Example 3 is as Figure 11 shown.

[0079] After statistics, Figure 4 、 Figure 10 、 Figure 11 the average diameters of the sample structures are 16.0±1.1, 12.5±0.8 and 15.5±1.0 μm respectively. It can be seen that the pore diameter distributions of the sample structures are relatively uniform. Such a highly uniform structure can enable the pores to form a better sensing response linearity during the deformation process, thereby generating a more uniform change in electrical properties. At the same time, the highly oriented structure further verifies the reliability of the directional freezing method for preparing the oriented sodium alginate / Ti3C2T x MXene composite sponge structure.

Claims

1. A multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, characterized in that: It includes a PVDF fiber membrane layer located in the middle, porous sponge layers located on both sides of the PVDF fiber membrane layer, and an electrode layer located between the PVDF fiber membrane layer and the porous sponge layers. The electrode layer is distributed on the porous sponge layers, and the porous sponge layers and the PVDF fiber membrane layer are formed by hot pressing and bonding. The PVDF fiber membrane layer is formed by the interweaving of fiber filaments with a diameter in the nanometer range. The porous sponge layer includes a composite sol matrix and Ti3C2T x Mxene and magnetic microparticles. There are concave-convex contact surfaces between the PVDF fiber membrane layer and the electrode layer, and between the electrode layer and the porous sponge layer. The concave-convex contact surfaces are formed during the hot pressing and bonding process due to the pore structure of the PVDF fiber membrane layer.

2. A multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, characterized in that: The thickness of the PVDF fiber membrane layer is 9 - 12 μm.

3. A preparation method of a multi-responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, characterized in that: N, N-dimethylformamide, acetone, and PVDF microparticles are mixed to obtain an electrospinning solution. The electrospinning solution is sprayed onto a collector through a syringe to form a PVDF fiber membrane layer. The PVDF fiber membrane layer is placed between porous sponge layers with electrode layers provided on both opposite sides, and then the PVDF fiber membrane layer and the porous sponge layers are formed by hot pressing and bonding.

4. A preparation method of a responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, characterized in that: The preparation method of the porous sponge layer is as follows: Sodium alginate and polyvinyl alcohol are respectively added to distilled water. After being stirred evenly respectively, a composite sol matrix is obtained. Ti3C2T x Mxene and magnetic particles are dissolved in the composite sol matrix, and then glycerol and calcium chloride are added and stirred evenly, and then poured into a mold; First, the mold is placed in liquid nitrogen for directional freezing. After directional freezing and forming, the mold is then placed in a freeze dryer and freeze-dried to obtain the porous sponge layer.

5. A preparation method of a responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, characterized in that: The mass ratio of sodium alginate to polyvinyl alcohol is 1:1 - 4; Ti3C2T x The volume ratio of Mxene to the composite sol matrix is 0.5 - 3:

50.

6. The preparation method of a responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device as claimed in claim 4, characterized in that: The addition amount of liquid nitrogen is 1 / 3 - 2 / 3 of the mold height; the temperature in the freeze dryer is -50 - 70 °C, and the vacuum degree is below 10 Pa.

7. The preparation method of a responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, characterized in that: The volume ratio of N, N-dimethylformamide to acetone is 6:3 - 5.

8. The preparation method of a responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device according to claim 3, characterized in that: The distance between the syringe and the collector is 5 - 25 cm, the voltage range is 10 - 25 kV, the propulsion speed is 0.1 - 2 ml / h, and the spinning time is 8 - 16 h.

9. A preparation method of a responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, characterized in that: The hot pressing temperature is 50 - 100 °C, and the hot pressing time is 3 - 10 min.

10. A preparation method of a responsive sodium alginate / Ti3C2T x MXene / PVDF composite sensor device, characterized in that: The preparation method of the magnetic microparticles includes the following steps: 1), Carbonyl iron powder, magnetic Fe3O4 microparticles, and sodium chloride are mixed and then added to an aqueous gelatin solution and subjected to ultrasonic oscillation. Then, the coated magnetic microparticles are separated by a permanent magnet, and the magnetic microparticles are washed with deionized water and then dried. 2), Multi-walled carbon nanotubes are added to a mixed acid prepared from nitric acid and sulfuric acid, and an acidified multi-walled carbon nanotube solution is obtained after ultrasonic irradiation. 3), The gelatin-coated magnetic microparticles obtained in step 1) are added to the acidified multi-walled carbon nanotube solution prepared in step 2) and subjected to ultrasonic oscillation to make the multi-walled carbon nanotubes coat on the surface of the gelatin-coated magnetic microparticles. Then, the multi-walled carbon nanotube-coated magnetic microparticles are separated by a permanent magnet, washed with deionized water, and dried to obtain the magnetic microparticles.

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