Method for preparing multifunctional magnetic cilia array based on magnetic programming

Abstract

The invention provides a method for preparing a multifunctional magnetic cilia array based on magnetic programming, which comprises the following steps of: mixing a polymer and magnetic particles to obtain a magnetic mixture, and preparing the magnetic cilia array from the magnetic mixture by a mold reversing method, and performing magnetic programming on the magnetic cilia array to obtain the magnetic cilia array with a transportation function or a clamping function. The method has the beneficial effects that the method for preparing the multifunctional magnetic cilia array based on magnetic programming has the advantages of low cost and simple operation, can be suitable for the magnetic programming multifunctional magnetic cilia array in more scenes, and realizes multifunctional application of clamping and transporting cilia, thereby realizing control of the cilia on a macroscopic object, and improving the working efficiency. The magnetic cilium preparation method integrates material performance, preparation efficiency and multifunctional application.

Description

Technical Field

[0001] This invention relates to magnetic cilia arrays, and more particularly to a method for fabricating multifunctional magnetic cilia arrays based on magnetic programming. Background Technology

[0002] Cilia are elongated cellular projections composed of complex protein arrangements, playing a variety of important biological roles in various organisms (such as fluid transport, sensing, and particle removal). Currently, artificial cilia are mostly driven by magnetic fields, electric fields, or pneumatics. Among these, using magnetic fields to drive cilia has significant advantages: excellent biocompatibility, sensitive response, and non-contact actuation. The most common applications currently focus on achieving cilia anisotropy through magnetic chain-like clustering to simulate elementary wave motion, but do not involve the manipulation of macroscopic objects. Furthermore, traditional methods for programming and fabricating cilia require expensive equipment, complex experimental procedures, and stringent production conditions.

[0003] Therefore, there is a need for a method for preparing magnetic fibers that takes into account material properties, preparation efficiency, and multifunctional applications. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides a method for preparing a multifunctional magnetic cilia array based on magnetic programming.

[0005] This invention provides a method for preparing a multifunctional magnetic cilia array based on magnetic programming. The method involves mixing a polymer with magnetic particles to obtain a magnetic mixture, preparing a magnetic cilia array by molding the magnetic mixture using a mold, and then performing magnetic programming on the magnetic cilia array to obtain a magnetic cilia array with transport or gripping functions.

[0006] As a further improvement to the present invention, the mold is formed by 3D printing.

[0007] As a further improvement of the present invention, the polymer and carbonyl iron powder are mixed to obtain a magnetic mixture.

[0008] As a further improvement of the present invention, the magnetic particles are any one of carbonyl iron powder, magnetic powder, strontium oxyferrometallic material, neodymium iron boron, and magnetized neodymium iron boron.

[0009] As a further improvement of the present invention, the polymer is an elastomer.

[0010] As a further improvement of the present invention, the elastomer is made of Ecoflex platinum silicone.

[0011] As a further improvement of the present invention, a particle orientation method based on magnetic particles aligning to a magnetic field or a magnetization method based on a pulsed strong magnetic field is used to magnetically program the magnetic cilia array.

[0012] As a further improvement of the present invention, a rotating magnetic field provided by a Helmholtz coil is used to magnetically control the magnetic cilia array.

[0013] As a further improvement of the present invention, a Helmholtz coil is used to provide a frequency-stable rotating magnetic field.

[0014] As a further improvement of the present invention, a magnetic fiber array with a transport function is obtained by using a uniform rotating magnetic field to magnetically control the magnetic fiber array; the first fiber of the magnetic fiber array is magnetically controlled by a first uniform rotating magnetic field, and the second fiber of the magnetic fiber array is magnetically controlled by a second uniform rotating magnetic field, wherein the magnetic field directions of the first uniform rotating magnetic field and the second uniform rotating magnetic field are perpendicular, and the first fiber and the second fiber are arranged in alternate rows or columns.

[0015] As a further improvement of the present invention, a ciliary structure is designed, including the shape, length, thickness and arrangement of the cilia, and a mold with array holes is prepared according to the ciliary structure. The array holes are used to form a magnetic ciliary array.

[0016] As a further improvement of the present invention, the preparation process of the magnetic cilia array with transport function is as follows:

[0017] S1a, Prepare a mold with an array of holes;

[0018] S2a. Spray a layer of release agent onto the mold, so that the release agent covers the surface of the array holes and the surface of the mold; S3a. Fill the array holes with the magnetic mixture;

[0019] S4a. Place the mold in the magnetic field provided by the magnet to orient the particles.

[0020] S5a, A flexible substrate for preparing a magnetic cilia array;

[0021] S6a. After curing, remove the magnetic fiber array from the mold;

[0022] or;

[0023] S1b, Prepare a mold with arrayed holes;

[0024] S2b: Spray a layer of release agent onto the mold, so that the release agent covers the surface of the array holes and the surface of the mold; S3b: Fill the array holes with the magnetic mixture;

[0025] S4b, A flexible substrate for fabricating magnetic cilia arrays;

[0026] S5b. After curing, remove the magnetic fiber array from the mold;

[0027] S6b. Wrap the magnetic fiber array around a non-magnetic rod and magnetize the magnetic fiber array using a pulsed strong magnetic field.

[0028] S7b, Remove the magnetic cilia array from the non-magnetic rod.

[0029] As a further improvement of the present invention, S3a, the magnetic mixture is filled into the array holes, and the mold is placed in a vacuum drying oven to remove air and allow the magnetic mixture to penetrate into the mold.

[0030] As a further improvement of the present invention, S3a, the magnetic mixture is filled into the array holes, the mold is placed in a vacuum drying oven to remove the vacuum and degas, so that the magnetic mixture penetrates into the mold, and the excess magnetic mixture is scraped off with a glass plate.

[0031] As a further improvement of the present invention, S3b, the magnetic mixture is filled into the array holes, the mold is placed in a vacuum drying oven to remove the vacuum and degas, so that the magnetic mixture penetrates into the mold, and the excess magnetic mixture is scraped off with a glass plate.

[0032] As a further improvement of the present invention, the flexible substrate for preparing the magnetic cilia array includes: covering the mold surface and the cilia with a layer of pure polymer.

[0033] As a further improvement of the present invention, the preparation process of the magnetic cilia array with clamping function is as follows:

[0034] S1c, Prepare a mold with arrayed holes;

[0035] S2c: Spray a layer of release agent onto the mold, so that the release agent covers the surface of the array holes and the surface of the mold; S3c: Fill the array holes with the magnetic mixture in alternate rows or columns;

[0036] S4c, Place the mold in the magnetic field provided by the magnet to orient the particles;

[0037] S5c, Fill the remaining array holes with the magnetic mixture;

[0038] S6c, Rotate the magnet 90 degrees and place the mold in the magnetic field provided by the magnet to orient the particles; S7c, Prepare a flexible substrate for the magnetic cilia array;

[0039] S8c. After curing, remove the magnetic fiber array from the mold.

[0040] The beneficial effects of this invention are: it provides a method for preparing multifunctional magnetic cilia arrays based on magnetic programming, which has the advantages of low cost and simple operation, and can be applied to magnetic programming multifunctional magnetic cilia arrays in more scenarios. It realizes the multifunctional application of cilia for gripping and transporting, thereby realizing the manipulation of macroscopic objects by cilia. It is a magnetic cilia preparation method that takes into account material properties, preparation efficiency and multifunctional applications. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other solutions can be obtained based on these drawings without creative effort.

[0042] Figure 1 It is the hysteresis loop of soft magnetic materials and hard magnetic materials;

[0043] Figure 2 This is a schematic diagram of the magnetic programming principle of particle orientation method;

[0044] Figure 3 This is a schematic diagram of magnetic ciliary array fabricated using the particle orientation method;

[0045] Figure 4 This is a schematic diagram of particle-oriented magnetization.

[0046] Figure 5 This is a schematic diagram of a magnetic cilia array fabricated using the pulse magnetization method;

[0047] Figure 6 This is a schematic diagram of magnetization using the pulse magnetization method;

[0048] Figure 7 These are the morphological characteristics of four types of magnetic powder;

[0049] Figure 8 These are the hysteresis loops of five types of magnetic powder;

[0050] Figure 9 It is a cilia array prepared using a 3D printing molding method;

[0051] Figure 10 This is a schematic diagram of the motion of a ciliary array using a Helmholtz coil to apply a rotating magnetic field;

[0052] Figure 11 It is the ciliary deflection angle-magnetic field curve;

[0053] Figure 12 It is the time-varying wave motion of cilia;

[0054] Figure 13 It is a time-lapse photograph of the ciliary whip-like motion;

[0055] Figure 14 This is a schematic diagram of a ciliary array transporting EPS balls;

[0056] Figure 15 This is an example of EPS ball transport using fibers;

[0057] Figure 16 This is a schematic diagram of how cilia grip EPS balls;

[0058] Figure 17 This is a flowchart of the magnetic programming process for gripping the cilia array;

[0059] Figure 18 It is an instance of the ciliary array gripping behavior. Detailed Implementation

[0060] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0061] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0062] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0063] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0064] A method for preparing a multifunctional magnetic cilia array based on magnetic programming involves mixing a polymer with magnetic particles to obtain a magnetic mixture, preparing a magnetic cilia array by molding the magnetic mixture using a mold, and then performing magnetic programming on the magnetic cilia array to obtain a magnetic cilia array with transport or gripping functions.

[0065] The present invention provides a method for preparing a multifunctional magnetic cilia array based on magnetic programming. Its main advantages are: simple experimental equipment, convenient experimental operation, and low product cost; good controllability; material-structure-function synergistic design, and low-cost, rapid batch preparation; and controllable transportation and gripping of millimeter-scale objects, breaking through the size and functional limitations of traditional cilia.

[0066] This invention provides a method for preparing a multifunctional magnetic cilia array based on magnetic programming. Only one Helmholtz coil is needed to generate alternating and gradient magnetic fields, which can control the cilia array to achieve directional transport and static gripping of millimeter-sized objects (EPS balls).

[0067] 1.1 Fabrication and Magnetic Programming of Bionic Cilia Array

[0068] 1.1.1 Experimental Materials

[0069] The manufacture of magnetic fiber blankets mainly involves a composite mixture of polymers and magnetic particles. Ferromagnetic particles are microscopic entities made of ferromagnetic materials that retain their magnetization even after the removal of an external magnetic field. Therefore, among magnetic particles, ferromagnetic particles are widely used to construct magnetic fibers due to their strong response to external magnetic fields.

[0070] Ferromagnetic materials can be classified into soft magnetic materials or hard magnetic materials based on their magnetic properties. Figure 1 Soft magnetic materials exhibit low coercivity and low remanence, which facilitates magnetization and demagnetization. These materials also have low hysteresis losses, making them suitable for applications with frequently changing magnetic fields. Hard magnetic materials exhibit high coercivity and high remanence, requiring high magnetic fields for demagnetization. These materials also have high hysteresis losses, making them suitable for applications requiring permanent magnets.

[0071] Ecoflex is a polymer material, an organic series of silicone elastomers produced by Smooth-On. It is versatile and easy to use, and is known for its high elasticity, softness and environmental friendliness. It is widely used in fields such as flexible robots, biomedical engineering, soft robots, and biomimetic materials.

[0072] The magnetic cilia arrays fabricated in this project are mainly based on commercial magnetic powder and polymer materials. They are prepared by coating magnetic particles with a soft elastic matrix and using a molding method. The materials used in the experiment are shown in Table 1.

[0073] Table 1. Main materials used in the experiment.

[0074]

[0075] 1.1.2 Magnetic Programming Method

[0076] Different methods exist for magnetic programming of the two different types of magnetic particle materials mentioned above. One method is particle orientation based on the magnetic particles aligning to attract magnetic fields; the other is magnetization based on pulsed strong magnetic fields. Each method has its advantages and disadvantages, and the materials and methods used to create cilia are not entirely the same. The two cilia methods will be introduced below.

[0077] 1.1.2.1 Particle Orientation Method

[0078] The magnetism of a material originates from the magnetic moments of electrons and atomic nuclei within the atoms. The orbital motion of electrons generates the electron orbital magnetic moment, and the spin motion of electrons generates the electron spin magnetic moment. Figure 2 When these magnetic moments act in the same direction, they exhibit magnetism externally. This is also the intrinsic reason why ferromagnetic materials have remanence. When an external magnetic field is applied, due to the Lorentz force, the magnetic particles tend to align parallel to the external magnetic field, maintaining their internal magnetic moments while keeping the system in equilibrium. Therefore, the particle orientation method is mainly applicable to soft magnetic materials.

[0079] The specific preparation method for magnetic programming using particle orientation is as follows, and the preparation flowchart is shown in the figure. Figure 3 A magnetization diagram is shown below. Figure 4 As shown:

[0080] (1) Design the ciliary structure (ciliary shape, length, thickness, and arrangement), model the ciliary preparation mold, and 3D print it. Figure 3 (a) in the middle.

[0081] (2) Clean the printed fuzz mold with ethanol, and then spray a thin layer of EaseRelease onto the fuzz mold. TM Release agent, Figure 3 (b) in the middle.

[0082] (3) After thoroughly mixing and stirring the magnetic particles with the polymer to obtain a magnetic mixture, slowly invert it onto the fiber mold, place it in a vacuum drying oven to remove air, allowing the magnetic mixture to penetrate into the fiber mold, and scrape off the excess magnetic mixture with a glass slide. Figure 3 (c) in the middle.

[0083] (4) Insert the radial magnet into the magnet mold, and place the fiber mold in the magnetic field provided by the magnet for particle orientation. This step is called magnetic programming of the fibers. Figure 3 (d) in the middle.

[0084] (5) After curing, cover the cilia with a layer of pure polymer, which serves as the base for the cilia array. Figure 3 (e) in the middle.

[0085] (6) After curing, clean with isopropyl alcohol and carefully remove the fibers from the mold. Figure 3 (f) in the middle.

[0086] 1.1.2.2 Pulse Magnetization Method

[0087] During magnetization and demagnetization, the magnetization intensity (B or M) of a ferromagnetic material depends not only on the external magnetic field strength H but also on its original magnetization intensity Br. When an external magnetic field is applied to a ferromagnetic material, the magnetic dipoles of its atoms align themselves according to the external magnetic field. Even if the external field is removed, some dipole arrangements remain unchanged; at this point, the material is magnetized, possessing remanence Br. However, when magnetized by a magnetic field lower than the coercive field Hc, its remanence is retained. To demagnetize or change the magnetization, a magnetic field in the opposite direction with a strength greater than the coercive force must first be applied. Therefore, magnetization preparation methods based on pulsed magnetic fields are mainly applicable to hard magnetic materials.

[0088] The process for fabricating cilia using the pulse magnetization method is not entirely the same as that using the particle orientation method. The main difference lies in the magnetization method. The specific preparation method is as follows, and the preparation flowchart is shown in the figure. Figure 5 A magnetization diagram is shown below. Figure 6 As shown:

[0089] (1) Similar to particle orientation method, such as Figure 5 (a) in the middle.

[0090] (2) Similar to particle orientation method, such as Figure 5 (b) in the middle.

[0091] (3) Similar to particle orientation method, such as Figure 5 (c) in the middle.

[0092] (4) After curing, cover the fibers with a layer of pure polymer and allow it to cure. Figure 5 (d) in the middle.

[0093] (5) Clean with isopropyl alcohol and carefully remove the cilia from the mold. At this point, the cilia are not yet programmed and need to be magnetized using a pulse magnetizer: wrap the cilia around a non-magnetic rod, place it on the magnetizer's working platform, adjust the voltage to maximum, step on the magnetization pedal to complete the magnetization, adjust the voltage to zero, release the remaining voltage, and turn off the power to obtain the magnetized cilia array. Figure 5 (e) in the middle.

[0094] (6) Remove the cilia from the non-magnetic rod to obtain a programmed magnetic cilia array, such as... Figure 5 (f) in the middle.

[0095] 1.1.3 Characterization of Experimental Materials and Selection of Magnetic Programming Methods

[0096] Magnetic particles, as the response units of the ciliary array, play a crucial role in achieving ciliary deformation. Therefore, the choice of magnetic programming method depends on the selection of magnetic materials. However, higher magnetization is not always better; suitable magnetic particles must be selected based on the ciliary's properties and deformation characteristics. This project focuses on the coercivity and magnetization of ferromagnetic particles, as well as their morphological features, when selecting magnetic particles for ciliary fabrication. Coercivity refers to the strength of the reverse magnetic field required to reduce the magnetization of a material to zero, reflecting the material's resistance to demagnetization. Magnetization indicates the degree to which a material is magnetized under an applied magnetic field. Simultaneously, the morphological features of the magnetic particles affect the presence of defects in the prepared ciliaries. Therefore, this application characterizes the purchased magnetic particles using SEM and VSM, and analyzes and discusses their characteristics.

[0097] 1.1.3.1 SEM characterization

[0098] Neodymium iron boron (NdFeB), carbonyl iron powder (CIP), strontium ferrite (SrFeO), and magnetic powder (Fe3O4) showed significant differences in SEM images of single particles and particle clusters, such as... Figure 7 , Figure 7 In the image, (a) to (d) are SEM images of single particles of neodymium iron boron (NdFeB), carbonyl iron powder (CIP), strontium oxyferrite (SrFeO), and magnetite powder (Fe3O4), respectively; (e) to (f) are SEM images of the corresponding particle clusters, respectively. These differences mainly stem from their crystal structure, preparation methods, and physicochemical properties. In terms of single-particle morphology, NdFeB typically exhibits irregular polyhedral or angular shapes, with a rough surface and easily visible grain boundaries, reflecting its high brittleness and easy oxidation characteristics; CIP, prepared by vapor deposition, exhibits highly regular spherical shapes with smooth surfaces and occasional minor defects; SrFeO, due to its hexagonal crystal system, often appears as hexagonal plates or prisms with clear edges and flat crystal faces; Fe3O4 particles have diverse morphologies, possibly cubic, octahedral, or spherical, and their surfaces often have nanoscale pores, depending on the synthesis method. In the SEM images of the particle clusters, NdFeB particles form hard agglomerates due to their high surface energy and oxidation tendency, resulting in loose packing and numerous pores; CIP particles exhibit soft agglomeration due to van der Waals forces and magnetic interactions, with dense packing or chain-like arrangements, especially under a magnetic field; SrFeO plate-like particles tend to stack in an interlocking manner, forming a porous structure with mechanical interlocking at the edges; while Fe3O4 particle clusters exhibit an irregular packing morphology with blurred particle boundaries.

[0099] 1.1.3.2 VSM Characterization

[0100] The hysteresis loops of magnetized neodymium iron boron (u-NdFeB), neodymium iron boron (NdFeB), carbonyl iron powder (CIP), strontium ferrite (SrFeO), and magnetic powder (Fe3O4) are as follows: Figure 8 u-NdFeB and NdFeB exhibit very wide hysteresis loops, with extremely high coercivity and remanence, indicating that their magnetic domains are highly oriented and difficult to demagnetize. In contrast, CIP exhibits typical soft magnetic characteristics, with its narrow and thin hysteresis loop, extremely low coercivity, and high saturation magnetization, making it an ideal choice for high-frequency applications. SrFeO falls between hard and soft magnetic, with moderate coercivity but low saturation magnetization, reflecting the magnetic anisotropy of its hexagonal crystal system, making it suitable for use as a low-cost permanent magnet. Fe3O4 exhibits a hysteresis-free S-type structure, and its moderate coercivity and low saturation magnetization are closely related to the magnetic moment cancellation effect in the inverse spinel structure.

[0101] 1.1.3.3 Selection of Magnetic Programming Method

[0102] By comparing and analyzing the SEM morphology images and VSM characterization results of the magnetic powders, the characteristics of the five types of magnetic powders are summarized in Table 2. Although magnetized NdFeB particles exhibit the highest magnetization intensity under low magnetic field conditions, meaning that cilia can undergo significant deformation or movement even under weak magnetic field driving, the high coercivity of NdFeB makes it difficult to demagnetize quickly under alternating magnetic fields, potentially leading to motion lag. Furthermore, the irregular particle shape causes numerous defects within the cilia when using NdFeB particles to create them, even resulting in cilia breakage. In contrast, carbonyl iron powder, a soft magnetic material with extremely low coercivity, enables rapid response in alternating magnetic fields. Simultaneously, its regular particle shape and uniform particle size distribution result in fewer defects in the fabricated cilia. Therefore, this application ultimately prefers to use carbonyl iron powder as the magnetic particle in the cilia and employs a particle orientation method for magnetic programming of the cilia.

[0103] Table 2 Comparison of properties of five types of magnetic powder

[0104]

[0105] 1.1.4 Example of fabrication of particle-oriented magnetic cilia array

[0106] like Figure 9 As shown, Figure 9In the middle, the left side shows cilia of different sizes with diameters of 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, and 2.0mm respectively; the middle and right sides show densely and sparsely arranged cilia arrays, with a diameter of 1.2mm and a height of 5mm respectively. The fabrication process of the cilia array using 3D printing technology involves simple silicone molding, and the cilia array is magnetically programmed using the particle orientation method in 4.2.2.1 (CIP and Ecoflex 00-30 mass ratio of 1:1), which allows for flexible customization of millimeter-level cilia arrays. Secondly, the magnetic hybrid material is injected into the mold through a casting process, covered with a pure polymer substrate, cured, and then demolded, requiring no further assembly. Furthermore, carbonyl iron powder (CIP) is used as the core magnetic material; its low coercivity, high saturation magnetization, and regular spherical morphology result in fewer structural defects in the cilia array and enable rapid response in alternating magnetic fields. Finally, carbonyl iron powder and elastomer (Ecoflex...) are... The flexible matrix obtained by mixing 00-30 has good deformation ability and durability.

[0107] 1.2 Motion of biomimetic magnetic cilia array under magnetic field

[0108] In the previous section, this invention proposed a 3D printing-based molding method for fabricating ciliary arrays, providing a reliable approach for the controllable synthesis of ciliary structures. However, to further evaluate the potential functionality of biomimetic magnetically programmed ciliary arrays, their dynamic motion behavior needs to be analyzed and characterized.

[0109] 1.2.1 Analysis of Factors Affecting the Magnetic Response of Cilia Array

[0110] The magnetization M of the cilia depends on the characteristics of the magnetic particles and the magnetic field strength. When the magnetic field strength is low, its magnitude is:

[0111] M = χH

[0112] Where χ is the magnetic susceptibility, which is positively correlated with the content of magnetic particles Φ in the cilia, and H is the external magnetic field strength. The bending of the cilia is driven by magnetic torque. The magnetic torque τ per unit length is:

[0113] τ=μ0m×H

[0114] Where μ0 is the free permeability and m is the magnetic moment per unit length.

[0115] Assuming the magnetic particles within the cilia are uniformly arranged, the total magnetic torque τ is obtained by integrating over the entire length of the cilia. total for:

[0116]

[0117] Treating the cilia as elastic beams, according to the moment balance equation, their curvature κ is:

[0118]

[0119] Where E is the elastic modulus and I is the moment of inertia of the cross section, the magnitude of which for a cylindrical cilia is:

[0120]

[0121] Where D is the diameter of the cilia.

[0122] In summary, we can conclude that the main influencing factors of the deformation response of cilia in a magnetic field are the magnetic field strength, the content of magnetic particles in the cilia, and the physical size of the cilia.

[0123] 1.2.2 Semi-quantitative analysis of the influence of ciliary array parameters on motion laws

[0124] A Helmholtz coil is a device consisting of a pair of identical circular coils placed parallel and coaxially, with the spacing equal to the radius of the coils. This design generates a uniform magnetic field in the central region between the two coils. Using Helmholtz coils to provide a series of rotating magnetic fields (15mT, 12mT, 9mT, 6mT, 3mT) of intensity to magnetically control a cilia array, such as... Figure 10 (a) Specifically, the rotation occurs when a magnetic field of constant strength, perpendicular to the X-axis, rotates clockwise at a constant angular velocity within the YOZ plane. When the rotating magnetic field is applied, the cilia will oscillate back and forth under the magnetic field. During this oscillation, the maximum angle of cilia deflection and the curvature of the cilia are positively correlated. Therefore, the cilia deflection angle θ can be used to approximate the curvature for analysis, such as... Figure 10 (b) in the middle.

[0125] Figure 10 In the diagram, (a) shows a schematic diagram and mathematical expression of the rotating magnetic field provided by a Helmholtz coil; (b) shows a schematic diagram of ciliary motion, where θ is the angle of deflection of the ciliary under the influence of the rotating magnetic field. The deflection of each ciliary is inconsistent because the ciliaries have been programmed with particle orientation.

[0126] In the previous section, this invention concluded that the influence of ciliary parameters on motion mainly lies in the influence of the magnetic particle content in the ciliary on magnetization intensity, and the influence of the ciliary diameter. Therefore, using the same magnetization method, a series of magnetic ciliary arrays were prepared with the same magnetic particle to polymer mass ratio (1:1) but different diameters (0.8 mm, 1.2 mm, 1.6 mm, and 2.0 mm, respectively), and a series with the same diameter (1.2 mm) but different magnetic particle to polymer mass ratios (0.5:1, 1:1, 1.5:1, and 2:1, respectively). By capturing ciliary oscillation videos, the maximum deflection angle θ of the ciliary at its extreme position was analyzed frame by frame. max Plot the maximum deflection angle versus magnetic field strength curve, as shown below. Figure 11As shown.

[0127] Figure 11 In the diagram, (a) represents magnetic particles with the same content but different diameters; and (b) represents magnetic particles with the same diameter but different content.

[0128] Depend on Figure 11 It can be seen that the factors affecting ciliary movement are not influenced by a single parameter, but by the combined effects of magnetic field strength, magnetic particle content, and ciliary size. Figure 11 (a) shows that although a larger diameter can increase the content of more magnetic particles, the bending of the cilia will gradually weaken as the moment of inertia of the cross section increases. Figure 11 (b) illustrates that although a higher proportion of magnetic particles can provide higher magnetization, the increase in the content of magnetic particles in the mixture leads to an increase in elastic modulus and enhanced magnetic domain coupling. The interaction between magnetic dipoles between particles inhibits the free rotation of magnetic moments, resulting in a decrease in effective magnetic susceptibility. Therefore, to achieve the specific function of a ciliary array, it is necessary to comprehensively consider and design the ciliary parameters while providing a magnetic field of appropriate strength.

[0129] 1.2.3 Elementary Wave Response of Cilia Array

[0130] Metachronal waves are a widely existing coordinated motion pattern in nature, characterized by adjacent moving units oscillating sequentially with a slight phase lag, forming a continuous wave-like motion, especially in cilia-bearing organisms. Studying the metachronal wave characteristics of magnetically programmed ciliary arrays can reveal the microscale coordinated motion laws of ciliary arrays, understand the biological functions and motion mechanisms of cilia, and help develop intelligent biomimetic devices that mimic cilia for transport.

[0131] Therefore, a Helmholtz coil was used to magnetically control the cilia array to analyze the elementary wave propagation process within half a cycle. The rotating magnetic field provided by the Helmholtz coil is as follows: Figure 12 As shown in (a), this is a uniform magnetic field rotating clockwise at a constant speed with a frequency of 0.2 s. -1 . Figure 12 In (b), a single ciliary has a diameter of 0.8 mm, a length of 4 mm, and a spacing of 4 mm. The frequency of the elementary wave transmission is twice the frequency of the rotating magnetic field. Every 0.63 s, the ciliary bounces once, and the elementary wave is transmitted to the next position. Therefore, the transmission cycle of the elementary wave takes 2.5 s. Within the same cycle of the magnetic field rotation, the magnetic fields of the two half-cycles are symmetrical. Even if the magnetic field directions are opposite, it will not affect the bending behavior of the cilia. Therefore, the elementary wave can be continuously transmitted on the ciliary array.

[0132] Figure 12 In the diagram, (a) represents the method of applying the magnetic field; (b) is a schematic diagram of the propagation of the time-dependent element wave, where ①-⑤ are the cilia numbers and the dashed box represents the position of the element wave propagation at that moment.

[0133] Time-lapse photography of the aforementioned ciliary array was captured over 10 oscillation cycles. The video was extracted frame by frame using frame stacking and then layered to create a dynamic trajectory effect, such as... Figure 13 The figure shows that each ciliary undergoes a two-dimensional symmetrical whip-like motion in the vertical plane. Although the response angles of some cilia to the magnetic field are not completely consistent, this is due to unavoidable material defects in the fabrication process and uneven deposition of magnetic particles. However, the overall results indicate that under a rotating magnetic field, the cilia can transmit time-varying waves in a relatively controllable manner.

[0134] 1.3 Transport and gripping functions of biomimetic magnetic cilia array

[0135] Inspired by the cooperative motion mode of heterogeneous wave elements, if the entire ciliary array is magnetically programmed at the system level, wave element motion can be induced, thereby realizing wave element transport functionality. At the individual ciliary level, by precisely controlling the driving characteristics of each ciliary in the array, different cilia can exhibit differentiated motion behaviors in a uniform magnetic field, thus enabling the design and implementation of gripping operations. Therefore, this invention designs different magnetic programming and driving methods for different target behaviors of the ciliary array, thereby fabricating a multifunctional magnetic ciliary array.

[0136] 1.3.1 Transport Cilia Array

[0137] 1.3.1.1 Cilia Array Transport Mechanism

[0138] A uniform rotating magnetic field is used to magnetically control the ciliary array. Each ciliary undergoes a two-dimensional symmetrical whip-like motion in a vertical plane, giving the ciliary array controllable elementary wave motion. When the curvature of the cilia is large enough, it can transport macroscopic non-magnetic objects placed on top of the cilia. During continuous transport of EPS balls, the cyclical oscillation of each ciliary on the array provides sufficient propulsion for transporting the EPS balls. By controlling the magnetic field, EPS balls can be continuously and effectively transported on the ciliary array, such as... Figure 14 As shown.

[0139] Figure 14 In the diagram, (a) represents the method of applying the magnetic field; and (b) represents the ciliary transport mechanism.

[0140] 1.3.1.2 Example of transporting EPS balls using a cilia array

[0141] A Helmholtz coil provides a rotating magnetic field to magnetically control the ciliary array. Because each ciliary is oriented differently by the particles, the ciliary array generates elementary wave motion. Figure 15 In (a), the magnitude of the rotating magnetic field is 15mT, the direction is perpendicular to the X-axis, and it rotates clockwise at a constant angular velocity in the YOZ plane. Figure 15In Figure (b), the EPS ball is positioned on the ciliary array at different times. As the cilia periodically oscillate, the EPS ball is transported to the other side. Therefore, it can be proven that the magnetic programming method for transporting the ciliary array is effective.

[0142] Figure 15 In the diagram, (a) represents the method of applying the magnetic field, and (b) represents the location reached by the EPS on the cilia array at different times.

[0143] 1.3.2 Ciliary array

[0144] 1.3.2.1 Ciliary Array Gripping Mechanism

[0145] When an external magnetic field is applied, the magnetic particles tend to align parallel to the field, maintaining their internal magnetic moments and keeping the system in equilibrium. By using particle-oriented magnetic programming to change the orientation of the magnetic particle clusters in each ciliary column, when a magnetic field is applied, the magnetic dipole moment in each cluster provides torque, causing the cluster to rotate and align with the magnetic field. Therefore, in a perpendicular magnetic field, cilia with different magnetic particle cluster orientations will have different responses and perform different behaviors. Figure 16 This enables the gripping function of the cilia array.

[0146] Figure 16 In the diagram, (a) shows no magnetic field applied; (b) shows an EPS ball being clamped with a magnetic field applied.

[0147] 1.3.2.2 Magnetic Programming for Clamping Cilia Arrays

[0148] Unlike the programming method for transporting cilia arrays, achieving the cilia gripping function requires particle orientation for each cilia. The specific difference lies in the filling of the magnetic mixture; instead, a "fill-orientation-curing" process is performed every other row (column) in the mold. The magnetic programming method is as follows, and the magnetic programming process is as follows: Figure 17 As shown:

[0149] (1) Print the mold and apply release agent.

[0150] (2) Fill the mold with the magnetic mixture in alternating rows (columns), such as Figure 17 (a) in the middle.

[0151] (3) Apply a magnetic field and perform magnetic programming. Two magnets with opposite magnetic poles are placed opposite each other. The magnetic field in the middle position can be approximated as a uniform field, such as... Figure 17 (b) in the middle.

[0152] (4) After the previous step has cured, fill the remaining holes, such as... Figure 17 (c) in the middle.

[0153] (5) Rotate the magnet mold to a symmetrical position and apply a magnetic field symmetrical to (3) for magnetic programming, such as... Figure 17(d) in the middle.

[0154] (6) After the previous step is cured, cover with pure polymer, and demold after curing.

[0155] 1.3.2.3 Example of Cilia Array Gripping Behavior

[0156] A Helmholtz coil provides a constant magnetic field to magnetically control an array of cilia; two rows of cilia with different magnetic particle arrangements will react differently. For example... Figure 18 As shown in (a), the magnetic field is directed along the Z-axis and has a magnitude of 15 mT; Figure 18 (b) shows the opening of cilia pairs 1 and 2, and 3 and 4 when no magnetic field is applied; Figure 18 In (c), under the application of a constant magnetic field, pairs of cilia (1 and 2, 3 and 4) move closer together, thus achieving a "clamping" behavior of the cilia, as shown in the dashed box. However, due to the limited magnetic field strength of the cilia Helmholtz coil (which can only provide a maximum magnetic field of 15 mT), the degree of cilia bending is small. Nevertheless, the cilia response before and after the application of the magnetic field is sufficient to demonstrate the effectiveness of the magnetic programming method.

[0157] Figure 18 In the diagram, (a) shows the method of applying the magnetic field; (b) is a top view of the ciliary array without applying the magnetic field; (c) is a side view of the ciliary array without applying the magnetic field; (d) is a top view of the ciliary array with the magnetic field applied; and (e) is a side view of the ciliary array with the magnetic field applied.

[0158] 1.4 Summary

[0159] This invention focuses on the fabrication and functional realization of biomimetic magnetic ciliary arrays. Through systematic experimental design and characterization analysis, the following innovative results were achieved: First, based on carbonyl iron powder (CIP) as the magnetic unit, and combined with particle orientation method, efficient magnetic programming of the cilia was realized, solving the problems of response hysteresis and structural defects in hard magnetic materials. Second, the relationship between ciliary deformation and magnetic field strength, magnetic particle content, and ciliary geometric parameters was established semi-quantitatively, revealing the multi-parameter synergistic regulation of ciliary motion and providing a theoretical basis for the performance design of biomimetic cilia. Finally, a dual-functional mode of the ciliary array was innovatively developed—achieving material transport by exciting time-dimensional wave motion through a uniform rotating magnetic field and achieving controllable gripping using a differentiated magnetic programming strategy, demonstrating the potential of the ciliary array in material transport and gripping functions. This research not only provides a new method for the design of biomimetic magnetic materials but also provides a reference for the development of miniaturized manipulation tools in complex environments.

[0160] The present invention provides a method for fabricating a multifunctional magnetic cilia array based on magnetic programming, which has the following advantages:

[0161] 1. The process of creating cilia using 3D printing technology allows for flexible customization of millimeter-level cilia, thereby meeting the performance requirements of cilia in different application scenarios;

[0162] 2. A low-cost, easy-to-operate, and integrated magnetic programming multifunctional magnetic cilia array technology is provided;

[0163] 3. It can transport and grip a large number of EPS balls, and can freely switch the ciliary function by changing the applied magnetic field.

[0164] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a multifunctional magnetic cilia array based on magnetic programming, characterized in that: A magnetic mixture is obtained by mixing a polymer with magnetic particles. A magnetic fiber array is prepared by molding the magnetic mixture using a mold. The magnetic fiber array is then magnetically programmed to obtain a magnetic fiber array with transport or gripping functions.

2. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 1, characterized in that: A magnetic mixture is obtained by mixing the polymer and carbonyl iron powder.

3. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 1, characterized in that: The magnetic particles are any one of carbonyl iron powder, magnetic powder, strontium ferrite, neodymium iron boron, and magnetized neodymium iron boron.

4. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 1, characterized in that: The polymer is an elastomer.

5. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 4, characterized in that: The elastomer is made of Ecoflex platinum silicone.

6. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 1, characterized in that: Magnetic programming of magnetic ciliary arrays is performed using a particle orientation method based on magnetic particles aligning with magnetic fields or a magnetization method based on pulsed strong magnetic fields.

7. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 1, characterized in that: A rotating magnetic field provided by a Helmholtz coil is used to magnetically control the magnetic cilia array.

8. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 1, characterized in that: A magnetic fiber array with transport function is obtained by magnetically controlling the magnetic fiber array using a uniform rotating magnetic field; the first fiber of the magnetic fiber array is magnetically controlled using a first uniform rotating magnetic field, and the second fiber of the magnetic fiber array is magnetically controlled using a second uniform rotating magnetic field. The magnetic field directions of the first and second uniform rotating magnetic fields are perpendicular, and the first and second fibers are arranged in alternate rows or columns.

9. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 1, characterized in that, The fabrication process of a magnetic cilia array with transport function is as follows: S1a, Prepare a mold with an array of holes; S2a. Spray a layer of release agent onto the mold, so that the release agent covers the surface of the array holes and the surface of the mold; S3a. Fill the array holes with the magnetic mixture; S4a. Place the mold in the magnetic field provided by the magnet to orient the particles; S5a, A flexible substrate for preparing a magnetic cilia array; S6a. After curing, remove the magnetic fiber array from the mold; or; S1b, Prepare a mold with an array of holes; S2b: Spray a layer of release agent onto the mold, so that the release agent covers the surface of the array holes and the surface of the mold; S3b: Fill the array holes with the magnetic mixture; S4b, A flexible substrate for fabricating magnetic cilia arrays; S5b. After curing, remove the magnetic fiber array from the mold; S6b. Wrap the magnetic fiber array around a non-magnetic rod and magnetize the magnetic fiber array using a pulsed strong magnetic field. S7b, Remove the magnetic cilia array from the non-magnetic rod.

10. The method for fabricating a multifunctional magnetic cilia array based on magnetic programming according to claim 1, characterized in that, The fabrication process of the magnetic cilia array with gripping function is as follows: S1c, Prepare a mold with arrayed holes; S2c. Spray a layer of release agent onto the mold so that the release agent covers the surface of the array holes and the surface of the mold. S3c: Fill the array holes with the magnetic mixture in alternating rows or columns; S4c, Place the mold in the magnetic field provided by the magnet to orient the particles; S5c, Fill the remaining array holes with the magnetic mixture; S6c. Rotate the magnet 90 degrees and place the mold in the magnetic field provided by the magnet to orient the particles. S7c, A flexible substrate for fabricating magnetic cilia arrays; S8c. After curing, remove the magnetic fiber array from the mold.

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