A micro tube robot and its assembling, driving and radial extrusion method

Abstract

The application discloses a kind of micro tube robot assembly, drive and radial extrusion method, assembly includes the following steps: step one, 0.05-2wt.% magnetic colloidal particles are assembled into two-dimensional monolayer colloidal film under xy plane oscillation magnetic field;Step two, z direction direct current magnetic field is applied and gradually increase magnetic field intensity, until monolayer colloidal film breaks into sheet;Step three, precession magnetic field is applied, sheet is bent to form the micro tube robot of dense hollow tubular structure;Drive: micro tube robot can be accurately controlled by three-dimensional magnetic field and drive direction and speed, hollow interior space is used to capture and transport micro cargo;Radial extrusion: micro tube robot assembled under oscillation magnetic field can realize radial direction repeated extrusion without breaking.The present application realizes metastable assembly from one-dimensional isotropic microspheres to three-dimensional micro tubular micro robots for the first time, is suitable for newtonian fluid and non-newtonian fluid, and can meet different application scenarios.

Description

TECHNICAL FIELD

[0001] The present application relates to a microtubule robot assembly and manipulation method, in particular to a microtubule robot and its assembly, driving and radial extrusion method. BACKGROUND

[0002] The complex assembly and disassembly process of independent individuals can realize advanced functions, such as microtubules in biological membranes, which can serve as a path for protein transport within cells and regulate the dynamic migration of cells. Colloid is an ideal artificial assembly unit, but the microtubule structure formed in the current research does not have the complex function of natural microtubules. Especially for the aggregates formed by isotropic assembly units (spheres), such as microtubules, complex structures have not been reported.

[0003] The current artificially prepared microtubule structure, such as the closed ring formed by DNA modified Janus particles (J.S. Oh et al., Nat. Commun. 10, 3936 (2019)), the bipolar ring and strip structure formed by magnetic Janus rods (J. Yan et al., Nat. Commun. 4, 1516 (2013)) and the tubular microstructure assembled by elliptical particles under the action of an electric field (J.J. Crassous et al., Nat. Commun. 5, 5516 (2014)), has simple and single function, does not have radial repeated extrusion effect, and is only suitable for Newtonian fluid, with limited application range. SUMMARY

[0004] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide a metastable microtubule robot assembly method that can be reversibly and repeatedly assembled, is suitable for Newtonian or non-Newtonian fluid, and has a large diameter control range. The present application further provides a microtubule robot driving method that can accurately control the driving direction and speed. The present application further provides a repeatable radial extrusion method for microtubule robots.

[0005] Technical solution: The microtubule robot assembly method of the present application comprises the following steps:

[0006] Step one, in a Newtonian fluid or non-Newtonian fluid, 0.05-2wt.% of dispersed paramagnetic colloidal particles are aggregated to form a two-dimensional monolayer colloidal film under the action of an oscillating magnetic field;

[0007] Step two, apply a direct current magnetic field and gradually increase the magnetic field strength, the direct current magnetic field is perpendicular to the oscillating magnetic field, and as the in-plane repulsive force increases, the monolayer colloidal film breaks into thin sheets, and the thin sheets change from parallel to the xy plane to perpendicular to the xy plane;

[0008] Step three, apply a precession magnetic field, the thin sheets bend and fold to form a dense hollow tubular structure microtubule robot.

[0009] Further, the magnetic colloidal microparticles are one or more of iron oxide, magnetite, iron, and composites thereof. The composites can be a base of a non-magnetic material that is later coated, doped, implanted with, or otherwise treated to become a paramagnetic material, preferably polystyrene colloidal microparticles doped with iron oxide.

[0010] Further, the magnetic colloidal microparticles have a diameter of 200 nm to 30 μm. The larger the diameter of the magnetic colloidal microparticles, the fewer the number of magnetic colloidal microparticles needed to form the microtube robot. The concentration of the magnetic colloidal microparticle dispersion also affects the diameter and length of the assembled microtube robot, with a greater concentration of magnetic colloidal microparticles resulting in a larger area of the colloidal film and a larger size of the microtube robot. Because there are many factors that can adjust the size of the microtube robot, the microtube robot has a wide range of applications. For example, 200 nm microparticles can be assembled into a microtube with a diameter of several microns, which can be used in physiological systems, while larger colloidal microparticles can be assembled into a microtube robot with a diameter of hundreds of microns for capturing and transporting larger diameter cargo.

[0011] Further, the magnetic colloidal microparticles can be surface modified with one or more of hydrophilic or hydrophobic materials, positively or negatively charged molecules, antibacterial materials, anticoagulant materials, proteinaceous materials, and anticancer drugs. The hydrophilic or hydrophobic materials or the positively or negatively charged molecules can change the interaction between the microparticles and the surface of the substrate. The antibacterial materials are one or more of silver or silver ion-containing materials, quaternary ammonium salt materials, tetracycline materials, and fluoroquinolone materials. The anticoagulant materials are one or more of dextran, cytarabine, clopidogrel, aspirin, and other anti-platelet materials. The proteinaceous materials can be attached to the surface of the substrate by physical adsorption or covalent coupling, including selectin. The anticancer drugs include paclitaxel and docetaxel, which can be attached to the surface of the functionalized colloidal microparticles without adversely affecting the magnetic properties of the colloidal microparticles. The magnetic colloidal microparticles of the microtube robot can be used to provide radiation therapy to a specific location in the body of a patient. For example, the magnetic field can be changed to heat the microtube robot, causing local hyperthermia and achieving the effect of treating tumor diseases.

[0012] Further, the surface of the magnetic colloidal microparticles can be smooth or modified by coating with other materials, such as gold spikes, to increase the surface roughness of the microtube robot and thereby increase the efficiency of rotation and translation.

[0013] Further, in step one, the Newtonian fluid includes deionized water with a surfactant, and the non-Newtonian fluid includes sheep whole blood. The main factor affecting the assembly process is the viscosity of the fluid. The range of applications depends on the degree of response of the paramagnetic microparticles to the magnetic field. Paramagnetic microparticles with weaker response are suitable for use with lower viscosity fluids, and vice versa.

[0014] Further, in step one, the oscillating magnetic field is where B ost is the oscillating magnetic field, B xy is the xy-plane alternating magnetic field intensity, ω M = 2πf M is the rotational angular velocity, f M = 50 Hz is the magnetic field frequency, is the magnetic field vector direction.

[0015] Further, in step two, the direct current magnetic field is where B z is the z-direction direct current magnetic field intensity, is the magnetic field vector direction.

[0016] Further, in step three, the precession magnetic field is where B prec is the precession magnetic field, B xy is the xy-plane alternating magnetic field intensity, B z is the z-direction direct current magnetic field intensity, ω M = 2πf M is the rotational angular velocity, f M = 20-50 Hz is the magnetic field frequency, is the magnetic field vector direction, arctan(B xy / B z ) is 8-20°.

[0017] The micro-tube robot obtained by the above assembly method is a metastable hollow tube structure assembled by paramagnetic colloidal particles under the action of a magnetic field, and after all the magnetic fields are removed, the micro-tube robot is disintegrated into paramagnetic colloidal particles, and can be reassembled by the assembly method.

[0018] The driving method of the micro-tube robot comprises the following steps: applying a driving magnetic field B prec ′ is the driving magnetic field, B yz is the yz-plane alternating magnetic field intensity, B x , B y , B z is the x or y or z-direction direct current magnetic field intensity. ω M = 2πf M is the rotational angular velocity, f M = 10-40 Hz is the magnetic field frequency, is the magnetic field vector direction. B z and (B x +B y ) proportional control the degree of inclination θ of the micro-tube relative to the z-axis, and the linear relationship is Microtube driving direction and DC magnetic field and The magnetic field vector is perpendicular to its projection direction on the xy plane; the driving magnetic field B prec The magnetic field strength adjusts the rotational angular velocity ω of the tilted microtube. For a microtube with diameter R, the relationship between its displacement velocity V and rotational angular velocity ω is V ~ ωRsinθ.

[0019] The present invention discloses a radial extrusion method for a microtubule robot: under a DC magnetic field. Under the condition that it exists, an oscillating magnetic field B is applied to the microtubule robot. ost The microtubule robot compresses rapidly along the radial direction, and the degree of compression is related to the oscillating magnetic field B. ost The magnetic field strength is positively correlated; the oscillating magnetic field B is removed. ost The microtubules slowly return to their original shape. Repeated application of an oscillating magnetic field B... ost It can achieve microtube circulation extrusion.

[0020] Furthermore, the strength of the applied magnetic field component depends on the magnetic responsiveness of the magnetic colloidal particles used. If the colloidal particles have a strong magnetic responsiveness, then a lower magnetic field strength will have an effect on them. The assembly time mainly depends on the initial concentration of the colloidal particles; a high concentration of colloidal particles helps to quickly form a sufficiently large colloidal film structure, thus completing assembly more quickly.

[0021] Furthermore, devices that generate magnetic fields include magnets in large equipment such as CT or NMR, multiple electromagnetic coils in small magnetic field devices, devices that generate magnetic fields by applying current or charge to conductive materials, and multiple magnets, etc. The magnetic field can be controlled in three dimensions (i.e., x, y, and z), so by adjusting the magnetic field composition, the tilting degree, rotation direction, rotation speed, and displacement direction of the microtubule robot can be flexibly controlled.

[0022] Preparation principle: Superparamagnetic microspheres exhibit different aggregation modes under the drive of a specific magnetic field. When different magnetic field components are applied in a programmed manner, superparamagnetic microspheres in the assembled state and monodisperse superparamagnetic microspheres will exhibit different aggregation forms, thereby realizing the preparation method of hollow tubular metastable structures in non-lowest energy states by applying a programmed magnetic field.

[0023] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0024] 1. For the first time, metastable assembly of one-dimensional anisotropic microspheres into complex three-dimensional microtubular microrobots has been achieved. This assembly method is applicable to both Newtonian and non-Newtonian fluids and can meet the needs of different application scenarios.

[0025] 2. Applicable to paramagnetic or superparamagnetic colloidal particles of different sizes, the assembled microtube robot has a wider range of adjustable diameter;

[0026] 3. The motion of the micro-tube robot can be precisely controlled by the magnetic field. The magnetic field components involve the combination of direct current field and alternating current field in a specific ratio range. The micro-tube hollow robot rolls near the wall surface under the driving of the magnetic field, realizes the accurate control of the cargo transportation and the predetermined route, and the magnetic field can control the tilt angle, the rotation angular velocity, the moving direction and the moving speed of the micro-tube robot. Compared with other micro-robots which also move in a rotating manner (the rotation-translation efficiency is usually 3% to 10%), the micro-tube robot has a higher rotation-translation efficiency, about 50%.

[0027] 4. The micro-tube robot can realize two cargo transportation modes. One is the non-contact cargo transportation mode, and the micro-tube forms an eddy current to drive the cargo to move during the rolling process. The other is that the micro-tube rolls to the target cargo by controlling the magnetic field, and the micro-tube is adjusted to stand again to realize the capture of the target cargo.

[0028] 5. When the oscillating magnetic field is applied, the micro-tube robot can realize the reciprocating compression function in the radial direction. When the soft objects such as red blood cells are trapped in the micro-tube, the observable deformation may occur in the compression process due to the compression force from the force between multiple adjacent particles. Therefore, the micro-tube robot in the application can be used as a movable micro-tweezer and become a potential tool for soft capsule drug release. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is the magnetic field device diagram of the application;

[0030] Figure 2 It is the assembly process schematic diagram of the micro-tube robot of embodiment 1 of the application, wherein a is the single-layer colloidal film broken into a strip structure, and b is the strip structure folded into a micro-tube;

[0031] Figure 3 It is the micro-tube robot of embodiment 1 of the application in B xy / B z The final structure phase diagram formed under different ratios;

[0032] Figure 4 It is the magnetic hysteresis loop diagram of the superparamagnetic microspheres of different sizes of embodiment 2 of the application, wherein A is a 30 μm microsphere, B is a 200 nm microsphere, C is a hollow micro-tube robot assembled by 30 μm microspheres, and D is a hollow micro-tube robot assembled by 200 nm microspheres;

[0033] Figure 5 It is the physical diagram of the micro-tube robot assembled by Newtonian fluid of the application;

[0034] Figure 6 It is the physical diagram of the micro-tube robot assembled by non-Newtonian fluid of the application;

[0035] Figure 7 is a correlation diagram of the tilting degree of the micro tube robot of embodiment 4 and the magnetic field vector and direction;

[0036] Figure 8 is a comparison diagram of the rotation translation efficiency of the micro tube robot of embodiment 4 and other micro robots;

[0037] Figure 9 is a rotation translation efficiency diagram of the micro tube robot of embodiment 4;

[0038] Figure 10 is a schematic diagram of the motion trajectory of the micro tube robot of embodiment 4 under the action of a magnetic field;

[0039] Figure 11 is a schematic diagram of the contactless carrying of goods by the micro tube robot of embodiment 4;

[0040] Figure 12 is a linear relationship diagram of the angular velocity ω of the micro tube robot of embodiment 4 and the displacement speed V of the polystyrene microspheres driven by the eddy current;

[0041] Figure 13 is a schematic diagram of the active capture of carrying goods by the micro tube robot of embodiment 4;

[0042] Figure 14 is a schematic diagram of the reversible radial compression of the micro tube robot of embodiment 4, wherein A is a structural change diagram of a micro tube in one extrusion cycle, and B is a relationship between the ratio of the long axis to the short axis of the micro tube and the number of extrusion cycles in the multiple cycle extrusion process;

[0043] Figure 15 is a schematic diagram of the compression deformation of the micro tube robot of embodiment 4 under different magnetic field strengths;

[0044] Figure 16 is a schematic diagram of the deformation of the micro tube robot of embodiment 5 under the action of an oscillating magnetic field, extruding red blood cells. DETAILED DESCRIPTION

[0045] In each of the following embodiments, a magnetic field device is used as shown in Figure 1 , a double-layer hollow copper coil 1 is superimposed in a nested doll manner to realize the superposition of direct current and alternating current fields in three dimensions (x, y, z) directions. The sample is placed at the cavity 2.

[0046] Embodiment 1

[0047] An assembly method of a micro tube robot, comprising the following steps:

[0048] (1) Dilute the superparamagnetic colloidal particle suspension with 0.5 wt.% sodium dodecyl sulfonate as a diluent, and take 10 μL of the suspension and sandwich it between two transparent glass slides. Place the glass slides on... Figure 1 In the magnetic field generating device shown.

[0049] (2) Dispersed superparamagnetic colloidal particles (mass fraction 0.2 wt.%) in an oscillating magnetic field Under the influence of these forces, they aggregate to form a two-dimensional monolayer colloidal film, such as... Figure 2 Ai, where B ost For an oscillating magnetic field, B xy Let ω be the alternating magnetic field strength in the xy plane. M =2πf M f is the rotational angular velocity. M =50Hz is the magnetic field frequency. The direction of the magnetic field vector. The applied magnetic field strength in this embodiment: B. xy =3.62mT,ω M =100πrad s -1 .

[0050] (3) Apply a magnetic field As the magnetic field strength is gradually increased, the entire monolayer colloidal film breaks into a thin sheet structure due to the increased in-plane repulsion. Among these, the DC magnetic field... Among them, B z The DC magnetic field strength is in the z-direction. The direction of the magnetic field vector is shown. The thin plate is tilted upwards relative to the xy plane. The oscillating magnetic field B is removed. ost The thin sheet is perpendicular to the xy plane and only at B z Maintaining integrity under the influence of the force verifies the stability of the vertical sheet structure, such as Figure 2 Aii~iv. The applied magnetic field strength B in this embodiment z =2.76mT.

[0051] (4) Apply a precessing magnetic field The thin sheet can bend and fold. Among them, B... prec For the precession magnetic field, B xy Let B be the alternating magnetic field strength in the xy plane. z ω represents the DC magnetic field strength in the z-direction. M =2πf M f is the rotational angular velocity. M =20-50Hz is the magnetic field frequency. The direction of the magnetic field vector. The applied magnetic field strength in this embodiment: B. xy =1.09mT,B z =2.76mT,ω M =60πrad s-1 Due to the difference of the rotational mobility, the end of the sheet which contacts with the body continues to curl until a dense hollow tubular structure is formed, as shown in Fig. 2B. Figure 2 Bi~vi. The components of the rotational field are different, and the final stable structure is not the same. The microtubular robot B xy is formed. z The ratio of B Figure 3 The range marked by the dot in the middle circle is arctanB xy / B z = 8~20°.

[0052] (5) Once the microtubule is formed, only the direct current component B z z-axis is retained, and the microtubule remains stable, which confirms the stability of the tubular assembly, as shown in Fig. 2C. Figure 2 Bvii, the strength of the applied magnetic field B z = 2.76 mT.

[0053] This embodiment shows the assembly process of the microtubular robot and the stability of the microtubule. Using simple isotropic superparamagnetic colloidal particles, a hollow microtubular structure is assembled through a designed assembly path. It should be noted that multiple microtubules can be formed each time, and the number of microspheres assembled into microtubules is different, so the diameter and length of the microtubule are also different.

[0054] Example 2

[0055] This embodiment shows that different sizes of superparamagnetic microspheres are assembled into microtubular robots under the same assembly path.

[0056] Different sizes of superparamagnetic microspheres are diluted with 0.5wt.% sodium dodecyl sulfate as a diluent, and 10 μL of the suspension is clamped between two transparent glass sheets. The glass sheets are placed in the magnetic field device shown in Fig. 3. Figure 1

[0057] The assembly steps are the same as in Example 1.

[0058] The field strength applied in the assembly process of 200 nm superparamagnetic microspheres is B ost : B xy = 3.62 mT, B z = 2.76 mT, ω M = 100π rad s -1 . B prec : B xy = 1.09 mT, B z = 2.76 mT, ω M = 60π rad s -1 . The field strength applied in the assembly process of 30 μm superparamagnetic microspheres is B ost : B xy ​= 3.62 ~ 5.43 mT, B z = 2.76 ~ 4.6 mT, ω M = 100π rad s -1 . B prec : B xy = 1.09 mT, B z = 2.76 ~ 4.6 mT, ω M = 60π rad s -1 .

[0059] As Figure 4 , both 30 μm and 200 nm superparamagnetic microspheres successfully assembled into hollow microtubule structures.

[0060] Example 3

[0061] This example demonstrates the assembly of superparamagnetic microspheres into microtubule robots in Newtonian or non-Newtonian fluids.

[0062] A suspension of superparamagnetic microspheres (final concentration 0.2 wt.%) with diameter 4.5 μm was diluted with 0.5 wt.% sodium dodecyl sulfate as a diluent (Newtonian fluid) or sheep whole blood (non-Newtonian fluid), and 10 μL of the suspension was sandwiched between two transparent glass slides. The glass slides were placed in the magnetic field setup shown in Fig. 1. Figure 1 The magnetic field strength applied was the same as in Example 1.

[0063] The assembly procedure was the same as in Example 1.

[0064] In Newtonian fluid, the magnetic field strength applied was the same as in Example 1.

[0065] In non-Newtonian fluid, the magnetic field strength applied was: B ost : B xy = 5.43 mT, B z = 4.6 mT, ω M = 100π rad s -1 . B prec : B xy = 1.09 ~ 1.45 mT, B z = 4.6 mT, ω M = 60π rad s -1 .

[0066] Final assembly results: In Newtonian fluid Figure 5 ) and non-Newtonian fluid Figure 6 ), both achieved assembly of superparamagnetic microspheres into hollow microtubule structures.

[0067] Example 4

[0068] This example demonstrates the functional roles of microtubule robots, such as motion control, cargo carrying, radial dynamic compression, etc.

[0069] A suspension of superparamagnetic microspheres with diameter of 4.5 μm (final concentration 0.2 wt.%) was diluted with 0.5 wt.% sodium dodecylsulfate as diluent. To demonstrate the cargo carrying effect of the microspheres, polystyrene microspheres with diameter of 10 μm (final concentration 0.001 wt.%) were added as cargo to the above suspension. 10 μL of the suspension was sandwiched between two transparent glass slides. The glass slides were placed in the magnetic field generating device shown in Fig. 1. Figure 1

[0070] The assembly procedure was the same as in Example 1.

[0071] The magnetic field strength applied in this example: B ost : B xy = 3.62 mT, B z = 2.76 mT, ω M = 100π rad s -1 . B prec : B xy = 1.09 mT, B z = 2.76 mT, ω M = 60π rad s -1 .

[0072] The microtube robot formed in this example can be precisely controlled in direction and speed of movement by an external magnetic field. The external magnetic field is B prec ' is the driving magnetic field, B yz is the strength of the alternating magnetic field in the yz plane, B x , B y , B z is the strength of the direct current magnetic field in the x or y or z direction. ω M = 2πf M is the angular velocity, f M = 10-40 Hz is the frequency of the magnetic field, is the direction of the magnetic field vector. The magnetic field strength applied in this example is: B yz = 1.81-2.71 mT, B x = 0-1.8 mT, B y = 0-1.8 mT, B z = 1.38 mT, ω M = 60π rad s -1 . Unlike the magnetoelastic film, the microtube robot advances as a rigid whole due to the restriction of the motion between the particles, avoiding severe fluid drag and improving the driving efficiency.

[0073] The microtube robot mainly moves in a rolling manner. B z and (B x + B​y ) the degree of inclination of the microtube with respect to the z-axis, θ, is linearly related to the ratio control The range of θ can be between about 0° (i.e., upright with respect to the surface) and 90° (i.e., lying flat on the surface), such as Figure 7 A larger degree of inclination will have a larger transmission efficiency, and a faster forward speed at the same driving strength. Compared with other rotating-driven micro-robots, the micro-robot in this embodiment has a higher conversion efficiency of rotation to translation, such as Figure 8 .

[0074] An important parameter in the motion of the microtube robot is the microtube displacement speed V, the microtube diameter R, and the microtube rotation angular velocity ω. The relationship between the translation and rotation speed is V ~ ωRsinθ, such as Figure 9 Compared with other micro-robots that also move in a rotational manner (1. Tierno, et al., Phys. Rev. Lett. 101, 218304 (2008); 2. Zhang, et al., Appl. Phys. Lett. 94, 064107 (2009); 3. Martinez-Pedrero, et al., Phys. Rev. Appl. 3, 051003 (2015); 4. Yang, et al., Proc. Natl. Acad. Sci. 117, 18186-18193 (2020); 5. Tottori, et al., Adv. Mat. 24, 811-816 (2012); 6. Ghosh, et al., Nano Lett. 9, 2243-2245 (2009); 7. Yang, et al., Sci. Robot. 4, eaaw9525 (2019); 8. Zhang, et al., ACS Nano 4, 6228-6234 (2012)), the conversion efficiency of rotation to translation is mostly in the range of 3% ~ 10%, and the microtube robot assembled in this embodiment has a significant improvement in efficiency (efficiency about 50%).

[0075] In addition to the displacement speed, the driving direction can also be manipulated by changing the combination of magnetic field components. The microtube driving direction is perpendicular to the projection direction of the magnetic field vector and the xy plane and The projection direction of the magnetic field vector and the xy plane. In this embodiment, in order to demonstrate the ability to control the driving direction of the microtube, the microtube is manipulated to advance in a closed trajectory, such as Figure 10 .

[0076] The hollow structure of the microtube robot makes them very suitable for the capture and transport of goods. In this embodiment, two capture modes are explored: contactless vortex capture and active approach to goods capture. In mode 1, a rapidly rotating microtube generates a vortex, and the fluid generates a force well to capture the goods. Therefore, the captured goods can be moved without contact with the microtube, such asFigure 11 The angular velocity ω of the microtube is linearly related to the displacement velocity of the polystyrene microspheres driven by the microtube vortex, as shown in Fig. 2B. Figure 12 The shapes represent different samples, and the hollow represents the microtube, and the solid represents the microsphere. In mode 2, since the magnetic field can exert precise driving direction control Figure 10 ), the microtube direction is adjusted to move to the top of the cargo to capture it. Once the cargo is trapped inside, the cargo can move together with the microtube, as shown in Fig. 2C. Figure 13 The diameter of the microtube robot can be adjusted and controlled by the volume of the colloidal particles constituting the microtube and the colloidal particle suspension concentration. The volume of the captured cargo ranges from several microns to hundreds of microns, which includes various cells, bacteria, and the like in a physiological environment, and thus can be used for cell, bacteria, and the like capture and separation in a physiological environment, as well as for mechanical property testing such as extrusion. Compared with other micro-robot lasso (T. Yang et al., Langmuir 33, 5932-5937 (2017)), the larger hollow structure of the microtube is more suitable for capturing cargo.

[0077] The microtube robot has a unique radial dynamic periodic compression function, as shown in Fig. 3A. Figure 14 A. Since the microtube is assembled by the dipole interaction between the microspheres, the structure is highly reconfigurable under the action of the external field. In B z Under the condition of maintaining the stable existence of the microtube robot, an oscillating field B ost : B xy = 0-3.15 mT, B z = 2.76 mT, ω M = 100π rad s -1 The microtube can be dynamically and periodically compressed without breaking Figure 14 A is a compression cycle period. The microtube in this embodiment can withstand at least ~ 90 times of compression and decompression without any structural damage, as shown in Fig. 4A. Figure 14 B, further demonstrating the stability of the microtube structure. During the compression process, the cross section of the microtube is deformed into an ellipse, and by increasing the field strength, the axial ratio between the short axis and the long axis decreases. Under the highest field strength condition in the experiment, the microtube in this embodiment has been compressed into almost two parallel layers (as shown in Fig. 4B, B Figure 15 ost = 3.15 mT), but still not broken.

[0078] Example 5

[0079] This embodiment demonstrates the extrusion effect of the microtube robot on cells. The superparamagnetic microspheres with a diameter of 2.7 μm are selected, and the assembled microtube has a diameter close to that of human red blood cells, to demonstrate more obvious extrusion effect.

[0080] ​A suspension of superparamagnetic microspheres with a diameter of 2.7 μm (final concentration 0.2 wt.%) was diluted with physiological saline or phosphate buffer solution containing 1 wt.% bovine serum albumin as diluent, and human red blood cells (0.01 wt.%) were added. 10 μL of the suspension was sandwiched between two transparent glass sheets. The glass sheets were placed in the magnetic field generating device shown in Fig. 1. Figure 1 The magnetic field generating device shown in Fig. 1 was used.

[0081] The assembly step was the same as in Example 1. The magnetic field strength applied during the assembly process was B ost :B xy = 3.6 mT, B z = 2.76 mT, ω M = 100π rad s -1 . The magnetic field strength applied during the assembly process was B prec :B xy = 1.45 mT, B z = 2.76 mT, ω M = 60π rad s -1 . During the extrusion process, the magnetic field strength applied was B ost :B xy = 3.15 mT, B z = 2.76 mT, ω M = 100π rad s -1 .

[0082] The microtube robot in this example can act as a movable micro-tweezer due to its unique function of radial dynamic periodic compression without breaking. In this example, when soft objects such as red blood cells are captured in the microtube, observable deformation occurs during the compression process due to the compression force from the inter-particle force of multiple adjacent particles, as shown in Fig. 2. Figure 16 Therefore, our microtube can act as a movable micro-tweezer, which is a potential tool for soft capsule drug release.

Claims

1. A method for assembling a microtubule robot, characterized in that, Includes the following steps: Step 1: In a Newtonian or non-Newtonian fluid, dispersed paramagnetic colloidal particles with a mass percentage of 0.05~2 wt.% aggregate under the action of an oscillating magnetic field to form a two-dimensional monolayer colloidal film. Step 2: Apply a DC magnetic field and gradually increase the magnetic field strength. The DC magnetic field is perpendicular to the oscillating magnetic field. As the in-plane repulsion increases, the monolayer colloidal film breaks into thin sheets, and the thin sheets change from being parallel to the xy plane to being perpendicular to the xy plane. Step 3: Apply a precessing magnetic field, causing the thin sheet to bend and fold, forming a microtubular robot with a dense hollow tubular structure.

2. The assembly method of a microtube robot according to claim 1, characterized in that: In step one, the paramagnetic colloidal particles are one or more of iron oxide, iron(II,III) oxide, iron, and their composite materials.

3. The assembly method of a microtubule robot according to claim 1, characterized in that: In step one, the particle size of the magnetic colloidal microparticles is 200 nm to 30 μm.

4. The assembly method of a microtubule robot according to claim 1, characterized in that: In step one, the magnetic colloidal microparticles are coated with one or more of the following: hydrophilic / hydrophobic materials, positively charged molecules, negatively charged molecules, antibacterial materials, anticoagulant materials, protein materials, and anticancer drugs.

5. The assembly method of a microtubule robot according to claim 1, characterized in that: In step one, the oscillating magnetic field is ,in, It is an oscillating magnetic field. Let X be the alternating magnetic field strength in the xy plane. Angular velocity of rotation The magnetic field frequency, The direction of the magnetic field vector. For time.

6. The assembly method of a microtubule robot according to claim 1, characterized in that: In step two, the DC magnetic field ,in, for Directional DC magnetic field strength, This indicates the direction of the magnetic field vector.

7. The assembly method of a microtubule robot according to claim 1, characterized in that: In step three, the precessing magnetic field ,in, For precessing magnetic field, Let X be the alternating magnetic field strength in the xy plane. for Directional DC magnetic field strength, Angular velocity of rotation The magnetic field frequency, The direction of the magnetic field vector. The angle is 8~20°. For time.

8. The microtubule robot obtained by the assembly method of a microtubule robot according to any one of claims 1 to 7, characterized in that: The microtubule robot is assembled into a metastable hollow tubular structure by paramagnetic colloidal microparticles under the action of a magnetic field. After all magnetic fields are removed, the microtubule robot disintegrates into paramagnetic colloidal microparticles.

9. The driving method for a microtube robot according to claim 8, characterized in that: Apply driving magnetic field , To drive the magnetic field, The strength of the alternating magnetic field in the yz plane. , , for or or Directional DC magnetic field strength, Angular velocity of rotation The magnetic field frequency, The direction of the magnetic field vector. and Proportional control microtubes relative to Axis tilt The linear relationship is , For time; microtube driving direction and DC magnetic field and Magnetic field vector sum in The projection directions on the plane are perpendicular; driving magnetic field Magnetic field strength adjustment of tilted microtube rotational angular velocity Diameter is The microtubes, their displacement velocity With rotational angular velocity The relationship is .

10. The radial extrusion method for a microtubule robot according to claim 8, characterized in that: In DC magnetic field Under the condition that it exists, an oscillating magnetic field is applied to the microtubule robot. The microtubule robot compresses rapidly along the radial direction, the degree of compression being related to the oscillating magnetic field. The magnetic field strength is positively correlated; the oscillating magnetic field is removed. The microtubule robot slowly returns to its original shape as an oscillating magnetic field is repeatedly applied. It can achieve micro-tube circulation extrusion.

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