Self-powered multifunctional sensor based on core sheath structure and manufacturing method thereof

Abstract

The invention relates to a self-powered multifunctional sensor based on a core-sheath structure and a manufacturing method thereof, the sensor adopts a double-layer composite structure: the upper part is a lead coil layer which is embedded in a liquid metal LM coil of a polydimethylsiloxane (PDMS) substrate; the lower part is a magnetic fiber network layer, the magnetic fiber network layer is a sensing network woven by magnetic liquid crystal elastomer LCE composite fibers with a core-sheath structure, an LCE hollow fiber pipe is used as an outer sheath, a fiber core layer compounded by strong magnetic particles / polyurethane penetrates through the inner part of the LCE hollow fiber pipe, and a gap between the outer sheath and the fiber core layer is filled with magnetorheological fluid to form a magnetic response interface; the two ends of the LCE hollow fiber pipe are fixed to the inner wall of the LCE hollow fiber pipe in a sealed mode in the mode that a flexible polymer material penetrates through the fiber core layers at the ends. The flexibility of the material is maintained, meanwhile, higher magnetic response performance is ensured, high-sensitivity pressure and temperature dual sensing is achieved, and the energy conversion and collection functions are achieved.

Description

Technical Field

[0001] The present invention relates to a flexible multifunctional sensor, belonging to the technical field of self-powered sensors, and in particular to a self-powered multifunctional sensor based on a core-sheath structure and a manufacturing method thereof. Background Art

[0002] With the rapid development of wearable technology and sensing technology, the demand for high-performance and multifunctional sensors is increasing day by day. Most traditional pressure sensors rely on external power supplies, and there are limitations in terms of energy utilization efficiency and environmental adaptability. In recent years, self-powered sensor technology has gradually emerged. By converting mechanical energy into electrical energy, it realizes the autonomous power supply of sensors, and at the same time has the function of energy harvesting, providing new ideas for the sustainable development of wearable devices and sensors.

[0003] However, although existing self-powered sensors have made certain progress in performance and functions, they still face many limitations in practical applications. In the prior art, for the combination method of magnetic materials and flexible materials, the scheme of directly doping magnetic particles in polymers is mostly adopted. This approach often makes it difficult to balance the magnetic field strength and flexibility, resulting in problems such as weak electrical signals due to weak magnetic field strength or failure of the flexible structure due to excessive doping of magnetic particles in actual use of the sensor. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a self-powered multifunctional sensor based on a core-sheath structure and a manufacturing method thereof.

[0005] The technical solution adopted by the present invention to solve the above technical problem is:

[0006] A self-powered multifunctional sensor based on a core-sheath structure, the sensor is a double-layer composite structure, namely an upper wire coil layer and a lower magnetic fiber network layer. The upper layer and the lower layer are adhesively fixed and assembled together through an adhesive layer to form a complete whole;

[0007] The magnetic fiber network layer is a fiber network woven by multiple LCE composite fibers. Each LCE composite fiber with a core-sheath structure has magnetism. The LCE hollow fiber tube is used as the outer sheath, and a fiber core layer composed of strong magnetic particles / TPU passes through the inside. The gap between the outer sheath and the fiber core layer is filled with magnetorheological fluid to form a magnetic response interface. Both ends of the LCE hollow fiber tube are hermetically fixed by a flexible polymer material passing through the end fiber core layer and the inner wall of the LCE hollow fiber tube.

[0008] Further, the wire coil layer includes a flexible substrate, a coil conductive circuit, and a packaging layer. The coil conductive circuit is fixed on the flexible substrate. The coil conductive circuit is printed in the shape of an Archimedean spiral with LM material. The two ends of the coil conductive circuit are respectively connected to copper wires by curing conductive silver paint. The two copper wires extend out of the flexible substrate. A packaging layer is provided on the coil conductive circuit to encapsulate the coil conductive circuit, the conductive silver paint, and part of the copper wires, forming an upper composite structure.

[0009] Further, the mass ratio of the ferromagnetic particles in the fiber core layer to the entire fiber core layer does not exceed 90%, and preferably the mass ratio of the ferromagnetic particles to the entire fiber core layer is 80-90%.

[0010] Further, the outer diameter of the LCE hollow fiber tube is 1-2 mm, and the inner diameter ratio of the fiber core layer to the LCE hollow fiber tube is 1:2-2:3.

[0011] The present invention also protects a method for manufacturing the self-powered multifunctional sensor based on the core-sheath structure, and the manufacturing method includes the following steps:

[0012] The first step: Prepare a flexible substrate;

[0013] The second step: Use a direct writing 3D printing platform to print liquid metal LM on the flexible substrate to form a coil conductive circuit, and use conductive silver paint to connect and fix the copper wires at both ends of the coil conductive circuit;

[0014] The third step: Use a direct writing 3D printing platform to uniformly print PDMS prepolymer on the coil conductive circuit prepared in the second step to maintain the coil conductive circuit and heat it to make a packaging layer, obtaining the upper composite structure of the sensor;

[0015] The fourth step: Add TPU particles to an organic solvent and dissolve them evenly to obtain a TPU solution. The organic solvent can both dissolve the TPU particles and dissolve in the coagulation liquid during the wet spinning process;

[0016] Then soak the ferromagnetic particles in the organic solvent and ultrasonically disperse them to obtain a suspension;

[0017] Finally, mix the suspension and the TPU solution evenly to obtain a TPU solution mixed with ferromagnetic particles;

[0018] Then prepare a TPU fiber mixed with ferromagnetic particles as the fiber core layer by wet spinning the TPU solution mixed with ferromagnetic particles;

[0019] The fifth step: Prepare an LCE hollow fiber tube; the LCE hollow fiber tube has flexibility and toughness, can insert the fiber core layer mixed with ferromagnetic particles into it, and can be woven by a textile weaving method;

[0020] Step 6: Pass the fiber core layer mixed with strongly magnetic particles through the hollow structure of the LCE hollow fiber tube, fill magnetorheological fluid between the LCE hollow fiber tube and the fiber core layer, and use a flexible polymer material as a package to encapsulate both ends of the LCE hollow fiber tube and fix the fiber core layer mixed with strongly magnetic particles to form an LCE composite fiber;

[0021] Step 7: Weave multiple LCE composite fibers into a magnetic fiber network layer by textile weaving method. After weaving, use an electric motor magnetizer to magnetize the fiber core layer to form a magnetic fiber network, which is the lower layer structure of the sensor. Then, apply PDMS between the upper composite structure and the lower layer structure of the sensor as an adhesive layer, and obtain the self-powered multifunctional sensor based on the core-sheath structure by hot pressing treatment.

[0022] Further, the specific process of the fifth step is as follows: Dissolve RM257, PETMP, DODT, DPA, and photoinitiator 651 in ethyl acetate and stir evenly by magnetic force to obtain a mixed solution. Inject the mixed solution into a silica gel tube, seal both ends, and place it in a vacuum oven. Evacuate to induce the permeation and evaporation of the solvent ethyl acetate to obtain an LCE prepolymer. Then, place the LCE prepolymer in the silica gel tube in an oven and heat it at 55 - 65 °C for 9 - 12 h. Finally, perform pre-stretching and ultraviolet curing on the silica gel tube for 10 - 20 min, and extract to obtain the LCE hollow fiber tube;

[0023] The molar ratio of PETMP to DODT is 1:4 - 1:6.

[0024] Further, the coil conductive circuit is printed by a direct writing 3D printing platform using a 21G needle; the TPU fiber wet spinning needle is printed using a 21G needle. The organic solvent is DMF, acetone, or tetrahydrofuran, and the corresponding coagulating liquid is deionized water, methanol, or ethanol.

[0025] Further: The inner diameter of the silica gel tube is 2 - 3 mm.

[0026] Further: The ratio of the diameter of the fiber core layer to the inner diameter of the LCE hollow fiber tube is 1:2 - 2:3. The mass ratio of the strongly magnetic particles to the entire fiber core layer is 80 - 90%, and the particle size range of the magnetic particles is 3 - 5 μm.

[0027] In the first step, the evacuation is to perform a 10 - minute vacuum treatment on the PDMS prepolymer.

[0028] In the second step, the coil conductive circuit is printed by a direct writing 3D printing platform using a 21G needle.

[0029] In the fourth step, the TPU fiber wet spinning needle is printed using a 21G needle, and the coagulation liquid used is deionized water.

[0030] In the fifth step, the vacuuming is to perform vacuum treatment on the mixed liquid for 2 hours, and the inner diameter of the silicone tube is 2 mm.

[0031] The ratio of the diameter of the fiber core layer to the inner diameter of the LCE hollow fiber tube 211 is 1:2.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The self-powered multifunctional sensor based on the core-sheath structure of the present invention has an energy collection function and can realize dual sensing of temperature and pressure while being self-powered. The specific technical effects are:

[0034] First point: It has the functions of self-power supply and energy collection. The sensor of the present invention has a unique structure and uses the deformation of the magnetic LCE composite fiber to drive the LM coil to cut the magnetic flux line, thereby generating an induced current and realizing the self-power supply function. At the same time, the sensor can also convert external mechanical energy or environmental thermal energy into electrical energy for energy collection, reducing the dependence on external power supply and improving the practicality and economy of the sensor.

[0035] Second point: It has a fiber core layer with uniform distribution of NdFeB particles. The strong magnetic particles (NdFeB) mixed in the fiber core layer of the LCE composite fiber are evenly dispersed after ultrasonic dispersion treatment, making the fiber magnetism more uniform and stable. In addition, the fiber core layer after wet spinning has uniform size and is easy to prepare, which reduces the overall preparation difficulty while ensuring the consistency and uniformity of the structure;

[0036] The third point: high-performance magnetic composite fiber, the magnetic LCE composite fiber has a core-sheath structure, with an LCE hollow fiber tube on the outside, and a fiber core layer composed of strong magnetic particles / TPU composite passing through the inside. After the later weaving, the whole is magnetized and magnetized to give the fiber network layer magnetism. The space between the LCE hollow fiber tube and the fiber core layer is filled with magnetorheological fluid, which is magnetized by the fiber core layer running through the LCE hollow fiber tube. This structure not only enhances the magnetism of the fiber, but also alleviates the problem of increased Young's modulus caused by magnetic particle doping through the flexible characteristics of the magnetorheological fluid, achieving a balance between magnetism and flexibility, and improving the sensitivity and stability of the sensor;

[0037] Fourth point: It has a cooperative double-layer composite structure and exhibits efficient pressure and temperature sensing performance. The synergistic effect between the upper wire coil layer and the lower magnetic fiber network layer enables the sensor to generate an induced current in the LM coil through the change in magnetic flux density in the face of pressure and temperature changes, achieving high-sensitivity sensing. This structure not only realizes the dual detection of pressure and temperature but also enhances the overall performance of the sensor through the interaction between the two layers. During application, when an external force acts on the sensor or the ambient temperature changes, the magnetic fiber network layer part woven with magnetic LCE composite fibers at the lower part deforms, thereby causing a change in magnetic flux density. As a result, a current is generated in the coil conductive circuit at the upper part due to the magnetic flux density, and high-precision detection of pressure or ambient temperature is achieved by detecting the current change. Even under a small pressure, a clear signal can be generated, improving the sensitivity of the sensor;

[0038] Fifth point: The upper and lower layers are adhesively assembled through PDMS to form a complete structure, which not only ensures the integrity of the sensor but also further enhances the flexibility and recovery ability of the sensor through the elastic properties of PDMS, enabling it to maintain stable performance during dynamic cycling;

[0039] Sixth point: It realizes multifunctional integration and application expansion. The sensor of the present invention can not only achieve pressure and temperature sensing but also serve as an energy harvesting device, converting external mechanical energy or ambient thermal energy into electrical energy, providing a new solution for the sustainable development of wearable devices and sensors, and having broad application prospects. The present invention not only enhances the sensitivity and stability of the sensor but also endows the sensor itself with self-power supply and energy harvesting functions, achieving a balance between high performance and high stability, ensuring the reliability and durability of the sensor in practical applications, and providing new ideas and methods for the development of high-performance sensors.

[0040] Seventh point: In the manufacturing method of the present invention, the addition of the organic solvent DMF enables the NdFeB particles to be evenly dispersed, avoiding the agglomeration phenomenon during the direct addition of them to the TPU solution; the LCE composite fiber is prepared by the fiber core layer mixed with strongly magnetic particles and the magnetorheological fluid, balancing the contradiction between magnetism and flexibility; by utilizing the unique properties of LCE, the dual detection of ambient temperature and external pressure by the sensor is achieved simultaneously, providing a new direction for the design of future multifunctional sensors. Description of the Drawings

[0041] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a schematic diagram of the overall structure of the self-powered multifunctional sensor based on the core-sheath structure provided by the embodiment of the present invention.

[0043] Figure 2 It is a schematic diagram of the structure of the wire coil layer of the self-powered multifunctional sensor based on the core-sheath structure in the unencapsulated state of the embodiment of the present invention.

[0044] Figure 3 It is a schematic diagram of the structure of the printed coil conductive circuit.

[0045] Figure 4 It is a schematic diagram of the structure of the magnetic fiber network layer of an embodiment.

[0046] Figure 5 is Figure 4 the top view of

[0047] Figure 6 It is a schematic cross-sectional view of the LCE hollow fiber tube.

[0048] Figure 7 It is a schematic diagram of the structure of the fiber core layer mixed with neodymium iron boron particles.

[0049] Figure 8 It is a schematic cross-sectional structure diagram of the LCE composite fiber of an embodiment.

[0050] Among them, wire coil layer 1, flexible substrate 12, coil conductive circuit 11, encapsulation layer 13, conductive silver paint 14, copper wire 15;

[0051] magnetic fiber network layer 2, LCE composite fiber 21, LCE hollow fiber tube 211, magnetorheological fluid 212, encapsulant 213; fiber core layer 214;

[0052] adhesive layer 3. Detailed implementation manners

[0053] To make the purpose, technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present invention.

[0054] Figure 1 It is one of the schematic diagrams of the self-powered multifunctional sensor based on the core-sheath structure provided by the embodiments of the present invention.

[0055] As Figure 1 shown, this embodiment provides a self-powered multifunctional sensor based on the core-sheath structure, which is a double-layer composite structure, namely the upper wire coil layer 1 and the lower magnetic fiber network layer 2. The upper layer and the lower layer are adhesively fixed and assembled together through the adhesive layer 3 to form a complete whole. The material used for the adhesive layer 3 is the same as that of the flexible substrate 12;

[0056] As Figure 2 shown, the wire coil layer 1 includes a flexible substrate 12, a coil conductive circuit 11, and a packaging layer 13. The coil conductive circuit 11 is fixed on the flexible substrate 12. The coil conductive circuit 11 uses an Archimedean spiral shape to print the LM circuit. The two ends of the coil conductive circuit 11 are respectively cured and connected to the copper wires 15 by conductive silver paint 14. The two copper wires 15 extend out of the flexible substrate 12. A packaging layer 13 is arranged on the coil conductive circuit 11 to encapsulate the LM conductive circuit, the conductive silver paint 14, and part of the copper wires 15 to form the upper composite structure;

[0057] As Figure 4 shown, the magnetic fiber network layer 2 is a fiber network woven by multiple LCE composite fibers 21. Each LCE composite fiber 21 has magnetism. Its outer sheath is an LCE hollow fiber tube 211, and a fiber core layer 214 mixed with neodymium iron boron particles after magnetization treatment passes through the inside. A magnetorheological fluid 212 is filled between the outer sheath and the core layer to form a magnetic response interface, and both ends are cured and encapsulated by encapsulants 213. In this embodiment, the encapsulants 213 use PDMS.

[0058] The upper and lower layers are adhesively assembled by using PDMS as the adhesive layer 3 to form a complete structure.

[0059] The woven magnetic fiber network layer 2 in the lower layer is woven by plain weave, twill weave or other weaving methods.

[0060] The coil conductive circuit 11 is formed on the surface of the flexible substrate 12 by using the liquid metal direct writing printing technology. The conductive silver paint 14 is used to realize the electrical connection between the two ends of the copper wire 15 and the LM, and the encapsulation protection is completed by secondary casting of PDMS to cover the LM conductive circuit and the conductive silver paint 14.

[0061] The coil conductive circuit 11 is formed by the direct writing 3D printing platform using needles such as 17G, 16G, 18G, 21G, etc. to print the liquid metal in multiple circles according to the set path and cure it.

[0062] Embodiment 1

[0063] The manufacturing method of the self-powered multifunctional sensor based on the core-sheath structure in this embodiment includes the following steps:

[0064] First step: Prepare the PDMS prepolymer with a PDMS:curing agent mass ratio of 10:1 and perform magnetic stirring for 10 min. Then, place the PDMS prepolymer in a vacuum oven and evacuate to remove air bubbles.

[0065] Spray the PDMS release agent on the glass slide. After it dries, spin-coat the PDMS prepolymer on the glass slide. After the spin-coating is completed, place it in an oven and heat-cure it at 100 °C for 30 min to obtain the flexible substrate 12.

[0066] Second step: Use a direct-write 3D printing platform to print LM on the flexible substrate 12 prepared in the first step to form the coil conductive circuit 11, and use conductive silver paint 14 to connect and fix both ends of the coil conductive circuit 11 to the copper wire 15.

[0067] Third step: Use a direct-write 3D printing platform to evenly print the PDMS prepolymer on the coil conductive circuit 11 prepared in the second step to maintain the coil conductive circuit 11 and heat it to fabricate the encapsulation layer 13 to obtain the upper composite structure of the sensor.

[0068] Fourth step: Add TPU particles to the dimethylformamide (DMF) solvent and stir with a mechanical stirrer at 50 °C to gradually dissolve the TPU and prepare the TPU solution. Then, soak the neodymium iron boron particles (with a particle size range of about 3 - 5 μm) in a small amount of DMF, treat them with an ultrasonic oscillator for 10 min, and stir appropriately until they are evenly dispersed to obtain a suspension. Finally, mix the suspension with the TPU solution in a certain ratio and stir with a mechanical stirrer for 30 min to prepare the TPU solution mixed with neodymium iron boron particles, and prepare the TPU fiber mixed with neodymium iron boron particles as the fiber core layer 214 by the wet spinning method.

[0069] DMF can be miscible with water and can effectively dissolve TPU particles. In the fiber core layer 214 mixed with neodymium iron boron particles, the mass of neodymium iron boron particles in the whole does not exceed 90%, which can ensure wet spinning forming. This method can introduce more magnetic particles and improve the overall magnetism.

[0070] Step 5: Dissolve RM257, PETMP, DODT, DPA, and photoinitiator 651 in ethyl acetate and stir magnetically for 10 min to obtain a mixed solution. Inject the mixed solution into a silica gel tube, seal both ends, and place it in a vacuum oven. Evacuate to induce the permeation evaporation of the solvent ethyl acetate to obtain the LCE prepolymer. Then, place the LCE prepolymer in the silica gel tube in an oven and heat it at 60 °C for 10 h. Finally, perform pre-stretching and ultraviolet curing on the silica gel tube for 10 - 20 min to extract the LCE hollow fiber tube 211;

[0071] The LCE hollow fiber tube 211 should not be too hard or too soft. Preferably, the molar ratio of the crosslinking agent PETMP to the chain extender DODT is 1:4 - 1:6;

[0072] Step 6: Embed the fiber core layer 214 mixed with neodymium iron boron particles into the hollow structure of the LCE hollow fiber tube 211, and fill the magnetic rheological fluid 212 between the LCE hollow fiber tube 211 and the fiber core layer 214 mixed with neodymium iron boron particles. Use PDMS as the encapsulant 213 (prepared with TPU flush with the hollow) to encapsulate both ends of the LCE hollow fiber tube 211 and fix the fiber core layer 214 mixed with neodymium iron boron particles to form the LCE composite fiber. At this time, the excess TPU fiber exposed outside the LCE hollow fiber tube can be cut off;

[0073] Step 7: Weave multiple LCE composite fibers 21 into a magnetic fiber network layer 2 by plain weaving. After weaving, use an electric motor magnetizer to magnetize the fiber core layer 214 to form a magnetic fiber network, which is the lower layer structure of the sensor. Then, use PDMS to coat between the upper layer and the lower layer as the adhesive layer 3, and obtain a self-powered multifunctional sensor by hot pressing. Use an electric motor magnetizer to magnetize the fiber core layer 214. The strong magnetic particles inside the fiber core layer 214 then guide the magnetic rheological fluid 212 to form the entire controllable magnetic field environment. Magnetize after weaving to avoid the problem of mutual cancellation between magnetic fields.

[0074] In the first step, the evacuation is a 10 - minute vacuum treatment of the PDMS prepolymer.

[0075] In the second step, the coil conductive circuit 11 is printed by a direct writing 3D printing platform using a 21G needle.

[0076] In the fourth step, the wet spinning needle of the fiber core layer 214 is printed using a 21G needle, and the coagulating liquid used is deionized water.

[0077] In the fifth step, the evacuation is a 2 - hour vacuum treatment of the mixed solution, and the inner diameter of the silica gel tube is 2 mm.

[0078] The ratio of the diameter of the fiber core layer 214 to the inner diameter of the LCE hollow fiber tube 211 is 1:2 to 2:3, which can ensure high magnetism.

[0079] Example 2:

[0080] See Figures 1 to 8 , a self-powered multifunctional sensor based on a core-sheath structure, which is a double-layer composite structure, namely the upper wire coil layer 1 and the lower magnetic fiber network layer 2. The upper layer and the lower layer are adhesively fixed and assembled together through an adhesive layer 3 to form a complete whole. The material used for the adhesive layer 3 is the same as that of the flexible substrate 12. The wire coil layer 1 includes a flexible substrate 12, a coil conductive circuit 11, and a packaging layer 13. The coil conductive circuit 11 is fixed on the flexible substrate 12. The coil conductive circuit 11 is printed in the shape of an Archimedes spiral with LM material. The two ends of the coil conductive circuit 11 are respectively cured and connected to copper wires 15 by conductive silver paint 14. The two copper wires 15 extend out of the flexible substrate 12. A packaging layer 13 is arranged on the coil conductive circuit 11 to encapsulate the coil conductive circuit 11, the conductive silver paint 14, and part of the copper wires 15 to form the upper composite structure. The magnetic fiber network layer 2 is a fiber network woven by multiple LCE composite fibers 21. Each LCE composite fiber 21 with a core-sheath structure has magnetism. Its outer sheath is an LCE hollow fiber tube 211, and a fiber core layer 214 mixed with neodymium iron boron particles and subjected to magnetization treatment passes through the inside. A magnetorheological fluid 212 is filled between the outer sheath and the fiber core layer 214 to form a magnetic response interface, and both ends are cured and encapsulated with PDMS;

[0081] The upper and lower layers are adhesively assembled with PDMS as the adhesive layer 3 to form a complete structure.

[0082] The woven magnetic fiber network layer 2 of the lower layer adopts a plain weave textile method.

[0083] Example 3:

[0084] The manufacturing method of a self-powered multifunctional sensor based on a core-sheath structure in this example includes the following steps:

[0085] The first step: Prepare a PDMS prepolymer with a PDMS:curing agent mass ratio of 10:1 and perform magnetic stirring for 10 min. Then place the PDMS prepolymer in a vacuum oven and evacuate to remove air bubbles;

[0086] Spray a PDMS release agent on a glass slide. After it dries, spin-coat the PDMS prepolymer on the glass slide. After the spin-coating is completed, place it in an oven and heat and cure it at 100 °C for 30 min to prepare the flexible substrate 12;

[0087] Step 2: Print the LM on the flexible substrate 12 prepared in the first step using a direct-write 3D printing platform to form a coil conductive circuit 11, and use conductive silver paint 14 to connect and fix the two ends of the coil conductive circuit 11 to the copper wire 15;

[0088] Step 3: Uniformly print the PDMS prepolymer on the coil conductive circuit 11 prepared in the second step using a direct-write 3D printing platform to maintain the coil conductive circuit 11 and heat it to fabricate the encapsulation layer 13 to obtain the upper composite structure of the sensor;

[0089] Step 4: Add 3 g of TPU particles to 7 mL of dimethylformamide (DMF) solvent, and stir using a mechanical stirrer at 50 °C to gradually dissolve the TPU to prepare a TPU solution;

[0090] After that, soak the neodymium iron boron particles in a small amount of DMF, treat them with an ultrasonic oscillator for 10 min, stir appropriately until dispersed, and finally mix them with the TPU solution in a ratio of neodymium iron boron:TPU mass ratio of 4:1, and stir using a mechanical stirrer for 30 min to prepare a TPU solution mixed with neodymium iron boron particles. Use the wet spinning method to prepare TPU fibers mixed with neodymium iron boron particles as the fiber core layer 214;

[0091] Step 5: Dissolve 0.8 g of RM257 and 0.022 g of photoinitiator 651 in 2 mL of ethyl acetate. Additionally, add 67 μL of crosslinking agent PETMP, 142 μL of chain extender DODT, and 29 μL of catalyst DPA to this ethyl acetate. Magnetically stir this solution for 10 min to obtain a mixed solution. Inject the mixed solution into a silicone tube, seal both ends, and place it in a vacuum oven. Evacuate to induce the permeation and evaporation of the solvent ethyl acetate to obtain an LCE prepolymer. Then, place the LCE prepolymer in the silicone tube in an oven and heat it at 60 °C for 10 h. Finally, perform pre-stretching and ultraviolet curing on the silicone tube for 10 - 20 min to extract the LCE hollow fiber tube 211; in this embodiment, the molar ratio of the crosslinking agent PETMP to the chain extender DODT is 1:5.

[0092] Step 6: Embed the fiber core layer 214 mixed with neodymium iron boron particles into the hollow structure of the LCE hollow fiber tube 211, fill the magnetic rheological fluid 212 between the LCE hollow fiber tube 211 and the fiber core layer 214, and use PDMS as the encapsulant 213 to encapsulate both ends of the LCE hollow fiber tube 211 and fix the fiber core layer 214 to form the LCE composite fiber 21;

[0093] Step 7: Weave multiple LCE composite fibers 21 into a magnetic fiber network layer 2 by plain weaving. After weaving, use an electric motor magnetizer to magnetize the fiber core layer 214 to form a magnetic fiber network, which is the lower layer structure of the sensor. Then, apply PDMS between the upper and lower layers as an adhesive layer 3, and obtain a self-powered multifunctional sensor through hot pressing treatment.

[0094] In this embodiment, the ratio of the diameter of the fiber core layer 214 to the inner diameter of the LCE hollow fiber tube 211 is 1:2, and the outer diameter of the LCE hollow fiber tube is 1.2 - 1.3 mm.

[0095] Example 4:

[0096] When an external force acts on the sensor or the ambient temperature changes, the magnetic fiber network layer 2 woven by the magnetic LCE composite fibers 21 deforms, thereby causing a change in the magnetic flux density. A current is generated in the coil conductive circuit 11 of the wire coil layer 1 due to the magnetic flux density, and the detection of the current change is used to detect the pressure or the ambient temperature.

[0097] Example 5:

[0098] When the sensor is continuously slapped externally or the ambient temperature changes continuously, the magnetic fiber network layer 2 deforms, and the magnetic flux density inside the coil conductive circuit 11 changes. A continuous current is generated by electromagnetic induction in the coil conductive circuit 11 of the wire coil layer 1. This current can be used to light an LED lamp or connect to an energy storage device to store electrical energy.

[0099] Matters not described in the present invention are applicable to the prior art.

Claims

1. A self-powered multifunctional sensor based on a core-sheath structure, characterized in that: The sensor has a double-layer composite structure, namely a wire coil layer on the upper layer and a magnetic fiber network layer on the lower layer. The upper layer and the lower layer are adhesively fixed and assembled together through an adhesive layer to form a complete whole; The magnetic fiber network layer is a fiber network woven from multiple LCE composite fibers. Each LCE composite fiber with a core-sheath structure has magnetism. The LCE hollow fiber tube serves as the outer sheath, and a fiber core layer composed of strongly magnetic particles / TPU passes through the inside. The gap between the outer sheath and the fiber core layer is filled with magnetorheological fluid to form a magnetic response interface. Both ends of the LCE hollow fiber tube are hermetically fixed to the inner wall of the LCE hollow fiber tube by passing a flexible polymer material through the fiber core layer at the end; 2. The self-powered multifunctional sensor based on the core-sheath structure according to claim 1, characterized in that: The wire coil layer includes a flexible substrate, a coil conductive circuit, and a packaging layer. The coil conductive circuit is fixed on the flexible substrate. The coil conductive circuit is printed in the shape of an Archimedean spiral with LM material. Both ends of the coil conductive circuit are respectively connected and fixed to copper wires by curing conductive silver paint. Two copper wires are led out of the flexible substrate, and a packaging layer is arranged on the coil conductive circuit to encapsulate the coil conductive circuit, the conductive silver paint, and part of the copper wires to form the upper-layer composite structure; 3. The self-powered multifunctional sensor based on the core-sheath structure according to claim 1, characterized in that: The mass ratio of the strongly magnetic particles in the fiber core layer to the entire fiber core layer does not exceed 90%, and preferably the mass ratio of the strongly magnetic particles to the entire fiber core layer is 80-90%; 4. The self-powered multifunctional sensor based on the core-sheath structure according to claim 1, characterized in that: The outer diameter of the LCE hollow fiber tube is 1-2 mm, and the inner diameter ratio of the fiber core layer to the LCE hollow fiber tube is 1:2-2:3; 5. A manufacturing method of the self-powered multifunctional sensor based on a core-sheath structure according to claim 1, characterized in that, The manufacturing method includes the following steps: The first step: Prepare a flexible substrate; The second step: Use a direct writing 3D printing platform to print liquid metal LM on the flexible substrate to form a coil conductive circuit, and use conductive silver paint to connect and fix the copper wires at both ends of the coil conductive circuit; The third step: Use a direct writing 3D printing platform to evenly print PDMS prepolymer on the coil conductive circuit prepared in the second step to maintain the coil conductive circuit and heat it to make a packaging layer, obtaining the upper-layer composite structure of the sensor; The fourth step: Add TPU particles to an organic solvent and dissolve them evenly to obtain a TPU solution. The organic solvent can both dissolve TPU particles and dissolve in the coagulating liquid during the wet spinning process; Then soak the strongly magnetic particles in the organic solvent and ultrasonically disperse them to obtain a suspension; Finally, mix the suspension and the TPU solution evenly to obtain a TPU solution mixed with strongly magnetic particles; Then prepare TPU fibers mixed with strongly magnetic particles as the fiber core layer by wet spinning the TPU solution mixed with strongly magnetic particles; The fifth step: Prepare an LCE hollow fiber tube; the LCE hollow fiber tube has flexibility and toughness, can insert the fiber core layer mixed with strongly magnetic particles into it, and can be woven by textile weaving methods; The sixth step: Pass the fiber core layer mixed with strongly magnetic particles through the hollow structure of the LCE hollow fiber tube, fill magnetorheological fluid between the LCE hollow fiber tube and the fiber core layer, and use a flexible polymer material as a packaging to encapsulate both ends of the LCE hollow fiber tube and fix the fiber core layer mixed with strongly magnetic particles to form an LCE composite fiber; Step 7: Weave multiple LCE composite fibers into a magnetic fiber network layer through textile weaving. After weaving, use an electric motor magnetizer to magnetize the fiber core layer to form a magnetic fiber network, which is the lower-layer structure of the sensor. Then, apply PDMS between the upper composite structure and the lower-layer structure of the sensor as an adhesive layer, and obtain the self-powered multifunctional sensor based on the core-sheath structure through hot pressing.

6. The manufacturing method according to claim 5, characterized in that, The specific process of the fifth step is as follows: Dissolve RM257, PETMP, DODT, DPA, and photoinitiator 651 in ethyl acetate and stir magnetically until evenly mixed to obtain a mixed solution. Inject the mixed solution into a silicone tube, seal both ends, and place it in a vacuum oven. Evacuate to induce the permeation and evaporation of the solvent ethyl acetate to obtain an LCE prepolymer. Then, place the LCE prepolymer in the silicone tube in an oven and heat it at 55-65°C for 9-12 hours. Finally, perform pre-stretching on the silicone tube and ultraviolet curing for 10-20 minutes, and extract to obtain an LCE hollow fiber tube. The molar ratio of PETMP to DODT is 1:4 to 1:

6.

7. The manufacturing method according to claim 6, characterized in that: The coil conductive circuit is printed by a direct-write 3D printing platform using a 21G needle; the TPU fiber wet-spinning needle is printed using a 21G needle. The organic solvent is DMF, acetone, or tetrahydrofuran, and the corresponding coagulating liquid is deionized water, methanol, or ethanol.

8. The manufacturing method according to claim 6, characterized in that: The inner diameter of the silicone tube is 2-3 mm.

9. The manufacturing method according to claim 6, characterized in that: The ratio of the diameter of the fiber core layer to the inner diameter of the LCE hollow fiber tube is 1:2 to 2:

3. The mass ratio of the ferromagnetic particles to the entire fiber core layer is 80-90%, and the particle size range of the magnetic particles is 3-5 μm.

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