Flexible magnetostrictive material and preparation method thereof

Abstract

The invention discloses a flexible magnetostrictive material and a preparation method thereof. The preparation method of the flexible magnetostrictive material comprises the following steps: selecting a high-viscosity polymer as a solvent; adding alloy powder into the solvent, and uniformly stirring to obtain magnetostrictive fluid ink; placing and fixing the flexible substrate on a motion platform; injecting the magnetostrictive fluid ink into a needle tube; a signal generator and a high-voltage amplifier are controlled to be started, so that high-voltage alternating current is generated between the tail end of a needle nozzle of the needle tube and the flexible substrate; and applying pressure to the magnetostrictive fluid ink by using a flow pump, and depositing the magnetostrictive fluid ink onto the flexible substrate according to a preset track. The preparation method of the flexible magnetostrictive material has the advantages of being simple in process, low in cost and controllable in rule, and has wide application prospects in the field of flexible electronic devices.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic functional materials, and in particular to a flexible magnetostrictive material and a preparation method thereof. Background Art

[0002] Magnetostrictive materials are functional materials with positive magnetostrictive effect and reverse magnetostrictive effect, which can complete the mutual conversion between mechanical energy, magnetic energy and electrical energy. This characteristic makes magnetostrictive materials have wide application potential in many fields. For example, in the field of electronics, magnetostrictive materials can be used to manufacture sensors and actuators. Magnetostrictive materials can deform according to the changes in the external magnetic field, and the corresponding signals can be obtained by detecting the changes in the deformation amount, which makes magnetostrictive materials have great application potential in the field of measurement and control. At the same time, magnetostrictive materials can also be used as an energy conversion material to convert mechanical energy into electrical energy, thereby realizing sustainable energy collection and reuse.

[0003] At present, terbium dysprosium iron, iron gallium alloy, iron nickel alloy, iron cobalt alloy, etc. are the most widely used magnetostrictive materials. These magnetostrictive materials, including Terfenol-D, Fe-Ga alloy and Fe-Co alloy, are widely used because of their excellent magnetostrictive properties at room temperature. They can sense and accurately respond to changes in the external magnetic field in real time, and then undergo significant magnetostrictive deformation. They have excellent deformation performance and high sensitivity and high precision. In addition, due to their good biocompatibility and low hysteresis loss, they can also be used to manufacture magnetic components in medical equipment, such as nuclear magnetic resonance (NMR) instruments used in magnetic resonance imaging (MRI) equipment.

[0004] In 2019, Nanjing University of Science and Technology used a low-temperature hydrothermal method to prepare a polyhedral FeCo alloy with a grain size of 1-2μm. The effects of heating time and molar ratio on the alloy structure and electromagnetic absorption properties were studied, and the obtained FeCo alloy particles are suitable as electromagnetic absorbing materials in the C, X, and Ku bands. The Second Hospital of Lanzhou University designed and manufactured a magnetostrictive spin valve with a FeGa / FeCo composite layer. Under a bias magnetic field of -30Oe, its strain sensitivity reached 7.2. Tokyo Metropolitan University obtained the magnetic properties of FeCo-2V alloy sheets with different structures from rods. The results showed that the inverse magnetostriction of the alloy after annealing showed good vibration power generation performance.

[0005] However, most of these magnetostrictive materials are used in the form of rigid cylindrical or sheet elements for manufacturing magnetic devices such as magnetic heads, sensors and inductors. They are difficult to bend and stretch on flexible substrates, and flexible electronic devices require magnetostrictive materials to adapt to and maintain a variety of shape changes. Even based on sheet-like magnetostrictive alloy elements, there are still difficulties in achieving complex shapes and structures suitable for flexible electronic devices. Therefore, the lack of ductility of magnetostrictive materials limits their application in flexible electronic devices. And they are prone to rupture under high stress, which also limits their use in some engineering applications and increases the complexity and cost of engineering system applications. Summary of the invention

[0006] The purpose of the present invention is to provide a flexible magnetostrictive material and a preparation method thereof, so as to solve the problem that the magnetostrictive material in the prior art lacks ductility.

[0007] In order to achieve the above-mentioned object, the present invention provides a method for preparing a flexible magnetostrictive material, the preparation method comprising the following steps: selecting a high-viscosity polymer as a solvent; adding alloy powder to the solvent and stirring to obtain magnetostrictive fluid ink; placing and fixing a flexible substrate on a moving platform; injecting the magnetostrictive fluid ink into a needle tube; starting a control signal generator and a high-voltage amplifier to generate high-voltage alternating current between the end of the needle nozzle of the needle tube and the flexible substrate; and applying pressure to the magnetostrictive fluid ink by using a flow pump to deposit the magnetostrictive fluid ink onto the flexible substrate according to a preset trajectory.

[0008] Furthermore, the high viscosity polymer is selected from one or more of phenolic resin, propylene glycol and epoxy resin; when multiple types are selected, they are first mixed evenly using a magnetic stirrer; the speed of the magnetic stirrer is 3000 r / min~5000 r / min, and the stirring time is 30min~75min; the viscosity of the solvent is 1500~2000cPs.

[0009] Furthermore, the alloy powder is selected from one or more of terbium-dysprosium-iron alloy powder, iron-cobalt alloy powder, iron-gallium alloy powder and iron-nickel alloy powder; the particle size range of the alloy powder is 20 μm to 60 μm.

[0010] Furthermore, when the alloy powder is added to the solvent, a dispersant is also added to the solvent; and the alloy powder, the dispersant and the solvent are stirred uniformly using an electric stirrer.

[0011] Furthermore, the dispersant is polyvinyl pyrrolidone; the added amount of the dispersant is 1 mg to 3 mg.

[0012] Furthermore, the flexible substrate is made of a biocompatible flexible material.

[0013] Furthermore, the material of the flexible substrate is silicon dioxide or polyethylene terephthalate.

[0014] Furthermore, after the step of injecting magnetostrictive fluid ink into the needle tube, the preparation method also includes the following steps: adjusting the distance between the end of the needle nozzle of the needle tube and the flexible substrate so that the distance between the end of the needle nozzle and the flexible substrate is 0.5mm~1.5mm; the waveform of the high-voltage alternating current is a square wave signal; the frequency of the high-voltage alternating current is 20Hz-60Hz, the amplitude is 600mV-2800mV, and the duty cycle is 20%~50%; the motion platform is an XY motion platform, and the moving speed of the motion platform is 200mm / s~800mm / s; the preset trajectory is a reciprocating structure, a mesh structure or a circular structure; the flow rate of the flow pump is 800nl / min~1600nl / min.

[0015] Furthermore, the preparation method further comprises the following step: packaging and curing the magnetostrictive fibers deposited on the flexible substrate to obtain a flexible magnetostrictive fiber tape.

[0016] Furthermore, the magnetostrictive fibers deposited on the flexible substrate were encapsulated by dimethylsiloxane.

[0017] According to the second aspect of the present invention, the present invention further provides a flexible magnetostrictive material, and the flexible magnetostrictive material is prepared according to the above-mentioned method for preparing the flexible magnetostrictive material.

[0018] The preparation method of the flexible magnetostrictive material provided by the present invention has simple process, low preparation cost, strong controllability, and can deposit a large-area magnetostrictive fiber structure on a flexible substrate material at one time, thereby improving production efficiency and being suitable for large-scale manufacturing. The preparation method of the flexible magnetostrictive material provided by the present invention can realize the bending and stretching of the magnetostrictive material on a flexible substrate, and the prepared flexible magnetostrictive material can adapt to and maintain a variety of shape changes, and can adapt to the complex shapes and structures of flexible electronic devices. The flexible magnetostrictive material provided by the present invention can be used in flexible electronic devices, is not prone to cracking under high stress, and is conducive to reducing the complexity and cost of engineering system applications.

[0019] Based on the implementations provided in the above aspects, this application can also be further combined to provide more implementations. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of 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.

[0021] Figure 1 The schematic diagram of preparing flexible magnetostrictive materials based on electrohydrodynamic printing technology; Figure 2 Schematic diagram of the structure of the prepared flexible magnetostrictive materials with different densities; Figure 3 Fe in the embodiment 50 Co 50 Preparation process of alloy fluid ink; Figure 4 Schematic diagram of a magnetostrictive fiber structure based on a long fiber structure in an embodiment; Figure 5 A flow chart of a method for preparing a flexible magnetostrictive material provided in an optional embodiment of the present invention; Figure 6 Schematic diagram of the bending test of the prepared flexible magnetostrictive materials with different densities; Figure 7 It is a schematic diagram of the structure of the Helmholtz coil test system; Figure 8 Schematic diagram of the output displacement signal of flexible magnetostrictive materials with different densities.

[0022] 1. XY motion platform; 2. Flexible substrate; 3. Nozzle; 4. Needle tube; 5. Magnetostrictive fluid ink; 6. Flow pump; 7. High-voltage amplifier; 8. Signal generator; 9. Packaging layer; 10. Magnetostrictive fiber. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0024] In an optional embodiment of the present invention, the present invention provides a method for preparing a flexible magnetostrictive material, the preparation method comprising the following steps: selecting a high-viscosity polymer as a solvent; adding alloy powder to the solvent and stirring to obtain a magnetostrictive fluid ink; placing and fixing a flexible substrate 2 on a moving platform; injecting the magnetostrictive fluid ink 5 into a needle tube 4; starting a control signal generator 8 and a high-voltage amplifier 7 to generate a high-voltage alternating current between the end of the needle nozzle of the needle tube 4 and the flexible substrate 2; applying pressure to the magnetostrictive fluid ink 5 using a flow pump, and depositing the magnetostrictive fluid ink 5 on the flexible substrate according to a preset trajectory to form a magnetostrictive fiber 10 on the flexible substrate 2.

[0025] The preparation method of the flexible magnetostrictive material provided by the present invention has simple process, low preparation cost, strong controllability, and can deposit a large-area magnetostrictive fiber structure on a flexible substrate material at one time, thereby improving production efficiency and being suitable for large-scale manufacturing. The preparation method of the flexible magnetostrictive material provided by the present invention can realize bending and stretching of the magnetostrictive material on a flexible substrate, and the prepared flexible magnetostrictive material can adapt to and maintain a variety of shape changes, and can adapt to the complex shapes and structures of flexible electronic devices.

[0026] Optionally, the high viscosity polymer is selected from one or more of phenolic resin, glycerol and epoxy resin; when multiple types are selected, they are first mixed evenly using a magnetic stirrer. Among them, phenolic resin has excellent high temperature resistance and is suitable for applications in high temperature environments; glycerol can improve the flexibility and impact resistance of materials when used as a plasticizer or cross-linking agent for multiple resins; epoxy resin has high mechanical strength and toughness after curing, and is suitable for high-strength engineering applications.

[0027] Optionally, the speed of the magnetic stirrer is 3000 r / min~5000 r / min. According to the test results, when using the magnetic stirrer to stir the solvent, the speed should not be too fast, which will cause too many bubbles in the solvent, and the speed should not be too slow, which will cause uneven stirring during the stirring of the solvent of the high-viscosity polymer. When the speed of the magnetic stirrer is within the above numerical range, the stirring effect is better, which can ensure uniform stirring and avoid excessive bubbles.

[0028] Optionally, the stirring time is 30 minutes to 75 minutes. A stirring time that is too long will result in low stirring efficiency, and a stirring time that is too short will result in uneven stirring. Within the above stirring time range, it can ensure that the high-viscosity polymer and the solvent are fully mixed, making the final mixture more uniform and helping to eliminate minor non-uniformities in the mixing, while not excessively increasing the processing time, thus balancing the stirring efficiency and mixing quality.

[0029] Optionally, the viscosity of the solvent is 1500-2000 cPs. When the viscosity of the solvent is within the above numerical range, the viscosity of the solvent is moderate, providing suitable fluidity, being high enough to maintain the required viscosity, achieving good uniformity during the stirring process, and avoiding the difficulty of stirring due to excessively high viscosity, and not being too high to affect the stirring effect.

[0030] In a specific embodiment of the present invention, phenolic resin and glycerol are selected and mixed evenly using a magnetic stirrer. The speed of the magnetic stirrer is 4500 r / min and the stirring time is 60 min.

[0031] Optionally, the alloy powder is selected from one or more of terbium-dysprosium-iron alloy powder, iron-cobalt alloy powder, iron-gallium alloy powder and iron-nickel alloy powder.

[0032] Optionally, the particle size of the alloy powder is in the range of 20 μm to 60 μm. When the particle size of the alloy powder is within the above numerical range, the alloy powder has good dispersibility during the mixing process and can be evenly distributed in the matrix material, thereby improving the overall performance of the final composite material. It can also effectively improve the mechanical strength and wear resistance of the composite material, while preventing processing difficulties or excessive bubbles from being generated due to too small a particle size.

[0033] In a specific embodiment of the present invention, the alloy powder is selected to have a particle size of 23 μm and a content of 50 wt% Fe 50 Co 50 Powder. The particle size of 23μm is moderate, which can ensure the uniform distribution of the powder in the matrix material, but will not cause difficulty in handling or excessive bubbles due to too small particle size. 50 Co 50 powder, which can ensure that Fe 50 Co 50 The alloy content is uniform, avoiding performance fluctuations caused by uneven composition.

[0034] Optionally, when adding the alloy powder to the solvent, a dispersant is also added to the solvent; the alloy powder, the dispersant and the solvent are stirred evenly using an electric stirrer. The addition of the dispersant can make the alloy powder and the solvent mix more evenly, thereby making the subsequent electrohydrodynamic printing process more stable and controllable.

[0035] Optionally, the dispersant is polyvinyl pyrrolidone. 50 Co 50Alloy powder is an inorganic substance, while the mixture of phenolic resin and glycerol is an organic substance. Polyvinylpyrrolidone has good surface activity and can effectively reduce the surface tension of powder in liquid, so that the powder can be evenly dispersed, avoiding powder agglomeration and ensuring the uniformity of the mixture. By reducing the interaction force between powders, PVP can prevent the powder from precipitating in the solution, thereby maintaining the stability of the mixture, and has the advantages of low toxicity and economy.

[0036] Optionally, the amount of dispersant added is 1 mg to 3 mg. When the amount of dispersant added is within the above numerical range, the dispersant can provide sufficient surface activity to effectively disperse the powder, avoid powder agglomeration, and ensure the uniformity of the mixture. Excessive use of dispersant may cause unnecessary viscosity increase or affect the properties of the final product. The addition range of 1 mg to 3 mg is an economical and reasonable choice that can achieve good dispersion effects without adding unnecessary costs.

[0037] In a specific embodiment of the present invention, the amount of dispersant added is 1 mg. The amount of 1 mg added can provide an appropriate amount of dispersant to ensure uniform dispersion of the powder in the liquid, avoid powder agglomeration, and maintain the stability of the liquid. Using a dispersant amount of 1 mg can minimize the use cost of the dispersant and avoid unnecessary waste.

[0038] Optionally, the flexible substrate is a biocompatible flexible material. Biocompatibility means that when the material contacts an organism (such as skin, tissue, cells, etc.), it will not cause obvious immune response or negative biological effects. Selecting a biocompatible flexible substrate can improve the safety and comfort of the material, expand the scope of application, and enhance product performance. These advantages make the prepared material have broad application prospects in the fields of medical treatment, health monitoring, etc.

[0039] Optionally, the material of the flexible substrate is silicon dioxide or polyethylene terephthalate, wherein polyethylene terephthalate and silicon dioxide are more flexible.

[0040] Optionally, after the step of injecting the magnetostrictive fluid ink into the needle tube, the preparation method further comprises the following step: adjusting the distance between the needle nozzle end of the needle tube and the flexible substrate so that the distance between the needle nozzle end and the flexible substrate is 0.5 mm to 1.5 mm. In this way, the distance between the needle nozzle end and the flexible substrate is close enough to ensure that the magnetostrictive fluid ink can be accurately sprayed to the target area, while not being too close to cause ink splashing or dripping. This helps to achieve high-precision pattern or structure spraying.

[0041] Optionally, the waveform of the high voltage alternating current is a square wave signal. The square wave signal can reduce the interference caused by the irregular waveform change, making the effect of the electric field more stable. The generation and control of the square wave signal are relatively simple, easy to implement and adjust, and reduce the complexity of the system.

[0042] Optionally, the frequency of the high-voltage alternating current is 20Hz-60Hz. Within the above frequency range, as the frequency of the electric field continues to increase, the number of electric field forces given to the solution by the electric field in the same time increases, and the solution jet flow rate also increases accordingly. Therefore, the deposited line width continues to increase with the increase of frequency, and the line width is positively correlated with the frequency during the overall experiment. When the frequency of the high-voltage alternating current exceeds this range, the trend of line width increase slows down at higher frequencies in the later stage, and the two are not linearly related. Selecting the above frequency range allows the line width to be controllably adjusted.

[0043] Optionally, the amplitude is 600mV-2800mV. The increase in voltage increases the electric field force on the solution, and the amount of solution sprayed per unit time increases, but the substrate movement speed does not change, so more solution is printed on a unit area of ​​the substrate. When the voltage continues to increase, the fluid is dragged excessively due to the excessive electric field force, and the continuity of the printed lines is poor, which is not suitable for actual processing applications. When the amplitude is within the above numerical range, the amount of the printed solution can be controlled without affecting the continuity of the lines.

[0044] Optionally, the duty cycle is 20%~50%. A reasonable duty cycle range enables the high voltage electrical signal to provide a stable magnetic field within a sufficient excitation time while avoiding system overheating or fluid loss caused by a long switching state. Adjustment of the duty cycle can help optimize the spraying and control performance of the fluid.

[0045] Optionally, the motion platform is an XY motion platform, and the moving speed of the motion platform is 200mm / s~800mm / s. The motion platform will drive the flexible substrate 2 to move, and the moving speed of the flexible substrate 2 will affect the printing effect. When the moving speed is within the above numerical range, it has a better printing effect. Within this moving speed range, as the moving speed of the flexible substrate 2 increases, the volume of the fluid sprayed in the fixed area of ​​the flexible substrate 2 per unit time decreases, and the line width also decreases accordingly. This is because as the speed increases, the drag force generated by the movement of the flexible substrate 2 on the jet also increases, while the flow rate of the fluid jet at the needle tip remains unchanged, and less fluid is accumulated on the substrate in the same time, so the print line width becomes smaller. In this way, the moving speed of the motion platform can be controlled to control the moving speed of the flexible substrate 2, thereby achieving effective control of the print line width.

[0046] Optionally, the preset trajectory is a reciprocating structure, a mesh structure, a long fiber structure or a circular structure.

[0047] Optionally, other structures may be designed according to actual needs.

[0048] Optionally, the flow rate of the flow pump is 800nl / min~1600nl / min. Too high a flow rate increases the difficulty of controlling the spraying amount and uniformity during the spraying process, because parameters such as the spraying time and the distance between the nozzle and the substrate need to be adjusted more accurately to avoid instability in the spraying process. And for some tiny nozzles, too high a flow rate may cause excessive pumping pressure, increasing the risk of nozzle clogging. Too low a flow rate may make it difficult to discharge bubbles in the liquid, or it may be difficult for tiny particles to be sprayed out with the liquid, thereby affecting the uniformity and quality of the spraying. When the flow rate of the flow pump is within the above numerical range, the spraying effect is better.

[0049] Optionally, the preparation method further comprises the following steps: encapsulating and curing the magnetostrictive fiber 10 deposited on the flexible substrate to obtain a flexible magnetostrictive fiber tape. After the magnetostrictive fluid ink in the needle tube 4 is deposited on the flexible substrate, the magnetostrictive fiber 10 is formed on the flexible substrate 2, and after encapsulation, an encapsulation layer 9 is formed on the magnetostrictive fiber 10. In this way, encapsulation and curing can prevent the material from being damaged during subsequent use.

[0050] Optionally, the magnetostrictive fibers deposited on the flexible substrate are encapsulated by dimethylsiloxane. Dimethylsiloxane is selected to encapsulate the magnetostrictive fibers due to its excellent flexibility, chemical compatibility, transparency, ease of processing, insulation properties, adhesion, and biocompatibility, which ensure the protective effect of the encapsulation layer and the stable performance of the magnetostrictive fiber ribbon during the encapsulation process.

[0051] The present invention also provides three flexible magnetostrictive materials with different densities. The flexible magnetostrictive materials are prepared according to the above-mentioned method for preparing the flexible magnetostrictive material.

[0052] In the illustrated embodiment of the present invention, optionally, the method for preparing the polydimethylsiloxane solution includes: mixing a main agent containing a PDMS component and a curing agent containing a cross-linking agent in a ratio of 10:1 to obtain a polydimethylsiloxane solution. Selecting to mix the PDMS main agent and the curing agent in a ratio of 10:1 can ensure good curing performance, optimize material properties, reduce bubble generation, improve processing convenience, and have wide applicability and flexibility.

[0053] Three flexible magnetostrictive materials with different densities are provided. The flexible magnetostrictive materials are prepared according to the above-mentioned method for preparing the flexible magnetostrictive material.

[0054] The flexible magnetostrictive material provided by the present invention can be applied in flexible electronic devices and is not prone to cracking under high stress, which is beneficial to reducing the complexity and cost of engineering system applications.

[0055] In an optional embodiment of the present invention, a method for preparing a flexible magnetostrictive material based on electrohydrodynamic printing technology is provided, which is mainly based on Fe 50 Co 50 The alloy material is prepared by electrohydrodynamic printing technology. This method is a non-contact micro-nano material processing method. It can print and deposit micro-nano fiber structures on different substrate materials. In the printing process, the Fe 50 Co 50 Specific parameters of alloy fibers, including width, height, etc.

[0056] In an optional embodiment of the present invention, a method for preparing a flexible magnetostrictive material based on electrohydrodynamic printing technology is provided, and the technical solution is as follows: (1) Using phenolic resin, propylene glycol, epoxy resin and other high-viscosity polymers as the main solvent, use a magnetic stirrer to mix them evenly; (2) adding magnetostrictive material alloy powder and dispersant to the uniformly mixed solvent obtained in step (1) in sequence, and mixing them uniformly using a mechanical electric stirrer to obtain a magnetostrictive fluid ink; (3) preparing a piece of biocompatible flexible material as the substrate for the printed flexible magnetostrictive fiber strip, and placing and fixing it on the XY motion platform; (4) designing a CAD structure as the motion trajectory of the magnetostrictive fiber 10, and adjusting the moving speed of the XY motion platform so that the magnetostrictive fluid ink is stably deposited on the flexible substrate material, thereby forming the magnetostrictive fiber 10 on the flexible substrate 2; (5) Injecting the magnetostrictive fluid ink prepared in step (2) into the needle tube, and adjusting the distance between the end of the needle nozzle and the flexible substrate. Under the joint action of the signal generator and the high-voltage amplifier, a high-voltage alternating current is generated between the end of the needle nozzle and the flexible substrate; (6) A precision flow pump is used to apply pressure to the magnetostrictive fluid ink, and a high-voltage electric field force and a mechanical stretching force are used to pull the magnetostrictive fluid ink out of the needle tube to form a Taylor cone, and finally the magnetostrictive fluid ink is deposited regularly and controllably onto a flexible substrate.

[0057] The flexible substrate is located on the XY moving platform. As the XY moving platform moves along the trajectory, the flexible substrate also moves, which forms a mechanical stretching force on the fluid ejected from the nozzle, thereby forming a preset trajectory.

[0058] (7) The magnetostrictive fiber printed in step (6) is packaged and cured to finally obtain a flexible magnetostrictive fiber ribbon.

[0059] Preferably, in step (1), the material of the solvent is a high-viscosity polymer such as phenolic resin, propylene glycol, epoxy resin, etc. A magnetic stirrer is used for stirring, and the speed is adjusted in the range of 3000 r / min-5000 r / min, and the stirring time is adjusted in the range of 30min-75min. According to the test results, when using a magnetic stirrer to stir the solvent, the speed should not be too fast, which will cause too many bubbles in the solvent, and the speed should not be too slow, which will cause uneven stirring during the stirring of the solvent of the high-viscosity polymer.

[0060] Preferably, in step (2), the magnetostrictive alloy powder is a magnetostrictive material such as terbium dysprosium iron alloy powder, iron cobalt alloy powder, iron gallium alloy powder, iron nickel alloy powder, etc., and its particle size can be adjusted in the range of 20 μm-60 μm. The dispersant is polyvinyl pyrrolidone, and its dosage can be adjusted in the range of 1 mg-3 mg. The addition of the dispersant makes the magnetostrictive alloy powder and the solvent prepared in step (1) more evenly mixed, making the subsequent electrohydrodynamic printing process more stable and controllable.

[0061] Preferably, in step (3), the biocompatible flexible material is a highly flexible material such as silicon dioxide or polyethylene terephthalate (PET).

[0062] Preferably, in step (4), the motion trajectory of the magnetostrictive fiber 10 is a reciprocating structure, a mesh structure, a long fiber structure, a circular structure, etc., and the adjustment range of the moving speed of the XY motion platform is 200 mm / s-800 mm / s.

[0063] Preferably, in step (5), the adjustment range of the distance between the needle nozzle end and the flexible substrate is 0.5 mm-1.5 mm, and the waveform of the high voltage alternating current is a square wave signal, the frequency of which is adjusted in the range of 20 Hz-60 Hz, the amplitude of which is adjusted in the range of 600 mV-2800 mV, and the duty cycle of which is adjusted in the range of 20%-50%.

[0064] Preferably, in step (6), the flow rate of the flow pump is adjusted in the range of 800 nl / min-1600 nl / min.

[0065] Preferably, in step (7), encapsulation is achieved by polydimethylsiloxane (PDMS), wherein the ratio of PDMS component to curing agent is preferably 10:1.

[0066] Specifically, the present invention proposes a method for preparing a flexible magnetostrictive material based on electrohydrodynamic printing technology, wherein the ink used is a magnetostrictive fluid, which is composed of a magnetostrictive alloy powder and a polymer solution with a high viscosity. The magnetostrictive fluid ink is placed in a closed needle and pressurized by a flow pump. A signal generator is used to generate a high-voltage square wave signal, which is transmitted to a power amplifier for amplification, and finally the positive pole of the high-voltage output signal is connected to the needle nozzle, and the negative pole is connected to the base material, so that a high-voltage electric field is formed at the nozzle and the base material, and then the ink is pulled out from the needle nozzle, and the magnetostrictive ink is regularly and controllably deposited on the base material in coordination with the mechanical stretching force of the XY motion platform.

[0067] Specifically, the printing trajectory is determined by the pre-designed CAD structure, including reciprocating structure, mesh structure, long fiber structure, circular structure, etc. The morphology of the printed magnetostrictive fiber is determined by the process parameters during the printing process, including voltage amplitude, voltage frequency, voltage duty cycle, the distance between the nozzle and the substrate material, the speed of the XY motion platform, the flow rate of the flow pump, etc.

[0068] Specifically, the direction of the mechanical stretching force can be controlled by designing the printing track. During the magnetostrictive fiber printing process, the direction of the mechanical stretching force determines the deflection direction of the magnetic domains inside the magnetostrictive material. According to the magnetostrictive effect, when the magnetic domains inside the magnetostrictive material are deflected, it causes internal strain in the material structure, which in turn causes the material to stretch in the direction of the magnetic field. Therefore, the performance of the prepared magnetostrictive can be improved by adjusting the printing track of the magnetostrictive material.

[0069] Specifically, in order to evaluate the magnetostrictive properties of flexible magnetostrictive materials, the magnetostrictive positive effect is used to test the deformation of the magnetostrictive material under the action of an external driving magnetic field. A Helmholtz coil can be designed to generate a stable driving alternating magnetic field. The prepared magnetostrictive material is fixed in the middle area of ​​a uniform driving magnetic field by a clamping fixture. A displacement sensor or strain gauge is used to measure the displacement of the free end of the magnetostrictive material under the influence of an external magnetic field, thereby characterizing its magnetostrictive positive effect.

[0070] In an optional embodiment of the present invention, a method for preparing a flexible magnetostrictive material based on electrohydrodynamic printing technology is provided, and the specific steps are as follows: (1) using a high-viscosity polymer such as phenolic resin, propylene glycol, epoxy resin, etc. as the main solvent, and adjusting the mixing ratio between the solvents to a suitable viscosity of the solvent. Using a magnetic stirrer, mix them evenly, and control the speed within the range of 3000 r / min-5000 r / min, and the stirring time within the range of 30min-75min; (2) Magnetostrictive materials such as terbium-dysprosium-iron alloy powder, iron-cobalt alloy powder, iron-gallium alloy powder, and iron-nickel alloy powder and dispersants are added to the uniformly mixed solvent obtained in step (1) in sequence. The particle size of the magnetostrictive alloy material powder is controlled between 20 μm and 60 μm. Polyvinyl pyrrolidone is selected as the dispersant, and its amount is controlled between 1 mg and 3 mg. Finally, a mechanical electric stirrer is used to mix uniformly to obtain a magnetostrictive fluid ink; (3) preparing a piece of biocompatible flexible material as the substrate for the printed flexible magnetostrictive fiber strip, including highly flexible materials such as silicon dioxide and polyethylene terephthalate (PET), and placing and fixing it on the XY motion platform; (4) Designing CAD structures such as reciprocating structure, mesh structure, long fiber structure, and circular structure as the motion trajectory of the magnetostrictive fiber, and controlling the moving speed of the XY motion platform between 200 mm / s and 800 mm / s to ensure that the magnetostrictive fluid ink is stably deposited on the flexible substrate material; (5) Inject the magnetostrictive fluid ink prepared in step (2) into the needle tube, and adjust the distance between the end of the needle nozzle and the flexible substrate to 0.5mm-1.5mm. Output a square wave voltage signal with a frequency of 20Hz-60Hz, an amplitude of 600mV-2800mV, and a duty cycle of 20%-50% to the voltage amplifier through a signal generator. Under the joint action of the signal generator and the high-voltage amplifier, a high-voltage alternating current is generated between the end of the needle nozzle and the flexible substrate; (6) A precision flow pump is used to apply pressure to the magnetostrictive fluid ink at a flow rate of 800nl / min-1600nl / min, and then a high-voltage electric field force and a mechanical stretching force are used to jointly drag the magnetostrictive fluid ink out of the needle tube to form a Taylor cone, and finally the magnetostrictive fluid ink is regularly and controllably deposited onto the flexible substrate.

[0071] (7) The magnetostrictive fiber printed in step (6) is encapsulated using polydimethylsiloxane (PDMS) with a ratio of PDMS component to curing agent of 10:1, and the PDMS is cured to obtain a flexible magnetostrictive fiber ribbon.

[0072] In order to better explain the present invention, a specific embodiment is given below: Figure 1 The schematic diagram of the method for preparing magnetostrictive fiber tape using electrohydrodynamic printing technology is shown in FIG. Figure 1As shown, it mainly includes an XY motion platform 1, a flexible substrate 2, a nozzle 3, a needle tube 4, a magnetostrictive fluid ink 5, a flow pump 6, a high-voltage amplifier 7, and a signal generator 8. The principle of the method is: the magnetostrictive fluid ink 5 is placed in the needle tube 4, the flow pump 6 generates pressure on the magnetostrictive fluid ink 5, the flexible substrate 2 is fixed on the XY motion platform 1, the signal generator 8 generates the required voltage signal, and transmits it to the high-voltage amplifier 7. The positive pole of the high-voltage amplifier 7 is connected to the nozzle 3, and the negative pole is connected to the flexible substrate 2. The magnetostrictive fiber belt finally printed is as shown in FIG. Figure 2 As shown, it is a "sandwich" structure, that is, the bottom layer is the flexible substrate 2, the middle layer is the magnetostrictive fiber 10, and the top layer is the packaging layer 9.

[0073] Example: Figure 2 As shown, three magnetostrictive fiber tapes based on long fiber structures with different densities were prepared by electrohydrodynamic printing technology, and their magnetostrictive properties were tested by Helmholtz coils.

[0074] (1) Select 100 mm × 100 mm × 0.1 mm polyethylene terephthalate (PET) as the flexible substrate material and fix it on the XY motion platform; (2) If Figure 3 and Figure 5 As shown, phenolic resin and propylene glycol were mixed in a ratio of 1:3, and stirred at a speed of 4500 r / min for 60 min using a magnetic stirrer until they were uniformly mixed. Fe with a particle size of 23 μm and a content of 50 wt% was added to the mixed solvent. 50 Co 50 The alloy powder and 1 mg of polyvinyl pyrrolidone were mixed with an electric stirrer until uniformly mixed to obtain Fe-based 50 Co 50 Fluid ink of alloy; (3) Prepare Fe-based 50 Co 50 The alloy fluid ink is placed in a needle tube, and the distance between the nozzle of the needle tube and polyethylene glycol terephthalate (PET) is controlled to be 1 mm. The ink in the needle tube is pressurized at a flow rate of 1200nl / min using a flow pump. A signal generator is used to output a square wave voltage signal with a frequency of 50Hz, an amplitude of 800mV, and a duty cycle of 50% to the voltage amplifier. The positive pole of the voltage amplifier is connected to the nozzle of the needle, and the negative pole is connected to the XY motion platform.

[0075] (4) Three different density-based long fiber structures were designed as motion trajectories, such as Figure 4The three long fiber structures shown. The factors considered in this paper through electrohydrodynamic performance are the mechanical tensile force that drags the magnetostrictive alloy ink to form a pre-designed trajectory. When the magnetostrictive alloy ink is dragged from the Taylor cone to form a specific fiber structure, the magnetic domains inside the material may be affected by it and deflected along the direction of the mechanical tension. Due to the influence of its shape anisotropy, the easy magnetization direction is parallel to the long axis of the fiber, which in turn causes the magnetic domains to be connected in series along the long axis, thereby producing a uniform magnetic moment in the fiber band. Even in the demagnetized state, the arrangement and distribution of the magnetic domains in the fiber band still affect the magnetic induction intensity, making it difficult to reduce it to zero. Each fiber band connects the magnetic domains in series in a longer band, and the easy magnetization axes of adjacent fiber bands are close, which causes them to interact with each other, thereby minimizing energy. The moving speed of the XY motion platform is 500mm / s, and finally, under the combined action of the high-voltage electric field force and the mechanical tensile force, the Fe 50 Co 50 The alloy fluid ink was regularly and controllably deposited onto polyethylene glycol terephthalate (PET) and finally encapsulated with polydimethylsiloxane (PDMS).

[0076] The bending test was carried out on the prepared flexible magnetostrictive materials with different densities, such as Figure 6 As shown, it can be seen that the flexible magnetostrictive material prepared in the present application has good flexibility.

[0077] In order to evaluate the magnetostrictive properties of the flexible magnetostrictive materials with different densities prepared above, a Helmholtz coil was designed to generate a stable driving magnetic field, thereby characterizing its ability to produce a positive magnetostrictive effect. Figure 7 As shown, the BP4610 power supply is used to power the Helmholtz coil, so that a uniform driving magnetic field is generated in the middle part of the Helmholtz coil, and the prepared flexible magnetostrictive material is fixed in the middle area of ​​the uniform driving magnetic field by a clamping fixture. A laser displacement sensor is used to measure the free end displacement of the flexible magnetostrictive material under the action of the external driving magnetic field, thereby characterizing its ability to produce a positive magnetostrictive effect.

[0078] When the BP4610 power supply is used to provide a bias current of 0.5A and an alternating current of 0.5A, the flexible magnetostrictive materials with different densities all generate displacement signals under the drive of the external magnetic field. 50 Co 50 The greater the density of the alloy covering, the greater its displacement output characteristics. Figure 8The time domain displacement output characteristics of three flexible magnetostrictive materials with different densities at their respective resonant frequencies are demonstrated. This verifies that the proposed method of preparing flexible magnetostrictive materials using electrohydrodynamic printing technology is effective, breaking through the bottleneck of the preparation of flexible magnetostrictive materials.

[0079] In this specific embodiment, the core component of the magnetostrictive material is Fe 50 Co 50 The preparation of the flexible magnetostrictive material includes the following steps: (1) mixing phenolic resin and propylene glycol in a ratio of 1:3 and using a magnetic stirrer to mix them evenly. Adding 50% Fe 50 Co 50 powder and 1 mg of polyvinyl pyrrolidone, and mix them evenly with an electric stirrer; (2) deposit the solution prepared in step (1) on polyethylene terephthalate (PET) by electrohydrodynamic printing technology; (3) apply dimethylsiloxane (PDMS) to the magnetostrictive fiber 10 deposited in step (2) for packaging to prevent the material from being damaged during subsequent use. The method for preparing the flexible magnetostrictive material proposed in the present invention has the characteristics of simple process, low cost and controllable rules, and has broad application prospects in the field of flexible electronic devices.

[0080] Compared with the prior art, the technical solution proposed by the present invention has the following advantages: (1) The method for preparing the flexible magnetostrictive material proposed in the present invention has a simple process, low preparation cost, strong controllability, and can deposit a large area of ​​fiber structure on the base material at one time, thereby improving production efficiency and being suitable for large-scale manufacturing; (2) The size of the deposited fibers can be controlled by adjusting the process parameters, thereby controlling the properties of the flexible magnetostrictive material. (3) The effect of mechanical stretching force on the internal magnetic domains of the material under different printing trajectories during electrohydrodynamic printing can improve the performance of the prepared magnetostrictive material.

[0081] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a flexible magnetostrictive material, characterized in that: The preparation method comprises the following steps: Use high viscosity polymer as solvent; adding alloy powder to the solvent and stirring evenly to obtain magnetostrictive fluid ink; placing and securing the flexible substrate on the motion platform; Injecting the magnetostrictive fluid ink into the needle tube; The control signal generator and the high-voltage amplifier are started to generate high-voltage alternating current between the needle nozzle end of the needle tube and the flexible substrate; A flow pump is used to apply pressure to the magnetostrictive fluid ink, and the magnetostrictive fluid ink is deposited onto the flexible substrate according to a preset trajectory.

2. The method for preparing a flexible magnetostrictive material according to claim 1, characterized in that: The high viscosity polymer is selected from one or more of phenolic resin, glycerol and epoxy resin; When choosing multiple types, first use a magnetic stirrer to mix them evenly; The speed of the magnetic stirrer is 3000 r / min~5000 r / min, and the stirring time is 30min~75min; The viscosity of the solvent is 1500-2000 cPs; The alloy powder is selected from one or more of terbium-dysprosium-iron alloy powder, iron-cobalt alloy powder, iron-gallium alloy powder and iron-nickel alloy powder; The particle size of the alloy powder ranges from 20 μm to 60 μm.

3. The method for preparing a flexible magnetostrictive material according to claim 1, characterized in that: When adding the alloy powder to the solvent, a dispersant is also added to the solvent; The alloy powder, dispersant and solvent are stirred evenly using an electric stirrer.

4. The method for preparing a flexible magnetostrictive material according to claim 3, characterized in that: The dispersant is polyvinyl pyrrolidone; The added amount of the dispersant is 1 mg to 3 mg.

5. The method for preparing a flexible magnetostrictive material according to claim 1, characterized in that: The flexible substrate is made of a flexible material with biocompatibility.

6. The method for preparing the flexible magnetostrictive material according to claim 5, characterized in that: The material of the flexible substrate is silicon dioxide or polyethylene glycol terephthalate.

7. The method for preparing a flexible magnetostrictive material according to claim 1, characterized in that: After the step of injecting the magnetostrictive fluid ink into the needle tube, the preparation method further comprises the following steps: adjusting the distance between the end of the needle nozzle of the needle tube and the flexible substrate so that the distance between the end of the needle nozzle and the flexible substrate is 0.5 mm to 1.5 mm; The waveform of the high voltage alternating current is a square wave signal; The frequency of the high voltage alternating current is 20Hz-60Hz, the amplitude is 600mV-2800mV, and the duty cycle is 20%-50%; The motion platform is an XY motion platform, and the moving speed of the motion platform is 200 mm / s to 800 mm / s; The preset track is a reciprocating structure, a mesh structure, a long fiber structure or a circular structure; The flow rate of the flow pump is 800nl / min~1600nl / min.

8. The method for preparing a flexible magnetostrictive material according to claim 1, characterized in that: The preparation method further comprises the following steps: packaging and curing the magnetostrictive fibers deposited on the flexible substrate to obtain a flexible magnetostrictive fiber ribbon.

9. The method for preparing a flexible magnetostrictive material according to claim 8, characterized in that: The magnetostrictive fibers deposited onto the flexible substrate are encapsulated by dimethylsiloxane.

10. A flexible magnetostrictive material, characterized in that: The flexible magnetostrictive material is prepared according to the method for preparing a flexible magnetostrictive material according to any one of claims 1 to 9.

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