Preparation and editing method of magnetic micro-nano robot with in-situ re-editing capability

Abstract

The invention discloses a preparation and editing method of a magnetic micro-nano robot with in-situ re-editing capability, and belongs to the field of micro-nano devices. Comprising the steps that a sacrificial layer is prepared through polyvinyl alcohol, pNIPAM is spin-coated, a flexible hinge layer is prepared through a photoetching technology, two magnetic driving modules are prepared through SU-8 pre-mixed with nickel nanowires with different diameters, the micro-nano robot is obtained after release, during reediting, a magnetic field can be applied externally to selectively magnetize one magnetic driving module or two magnetic driving modules are magnetized at the same time, and therefore the flexible hinge layer is prepared. And in-situ re-editing of the micro-nano robot is completed. The preparation process is simple, re-editing of the micro-nano robot can be achieved through a simple external magnetic field mode, more motion modes are provided, the problem that the motion mode of an existing micro-nano device is still rigid is solved, flexibility is further improved, and the micro-nano device has important application prospects in the fields of biological medicine, environment detection and the like.

Description

Technical Field

[0001] The invention relates to a preparation and editing method of a magnetic micro-nano robot with in-situ re-editing capability, and belongs to the technical field of micro-nano devices. Background Art

[0002] With the rapid development of micro-nano technology and the increasing demand in the biomedical field, magnetic micro-nano robots have become one of the research hotspots. Due to their small size, remote control, recyclability, and versatility, they have potential application prospects in biomedical fields such as drug delivery, imaging, surgery, and diagnosis. In biological tissue environments such as human blood vessels and intestines, the solid surface is uneven and the surface shape changes in a complex manner. This irregular surface hinders the movement of magnetic micro-nano robots. In order to improve the adaptability of micro-nano robots to the working environment, one way is to give micro-nano robots the ability to move in multiple modes.

[0003] At present, the multi-modality of magnetically driven micro-nano robots is mainly achieved by changing the size and type of the magnetic field or magnetically editing the micro-nano robot to change its magnetism. The motion mode of the micro-nano robot can be effectively changed by changing the size and type of the magnetic field, but the existing motion mode is still relatively rigid and lacks flexibility.

[0004] The magnetic editing of micro-nano robots is divided into pre-editing and real-time editing. Pre-editing refers to the introduction of a certain external field during the preparation of the micro-nano robot to magnetize different areas within the micro-nano robot to different states, but this method can only produce one pre-magnetization direction and cannot be changed; real-time editing means that the micro-nano robot can still change its magnetic state after being released into the working environment. This method can complete different magnetic state editing for the same micro-nano robot and adapt to complex environments.

[0005] Magnetic editing by means other than the intervention of a magnetic field is currently a common method, but increasing the type of external field will increase the difficulty of driving micro-nano robots. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing and editing a magnetic micro-nano robot with in situ re-editing capability, which reduces the size of the editable magnetic micro-nano robot to hundreds of microns in a simpler way, and enables magnetic editing and motion deformation control through magnetic field alone.

[0007] As one aspect of the present invention, a magnetic micro-nano robot with in situ re-editing capability is provided, comprising a magnetic drive layer and a flexible hinge layer, wherein the magnetic drive layer comprises a first magnetic drive module and a second magnetic drive module, and the first magnetic drive module and the second magnetic drive module are connected via the flexible hinge layer;

[0008] The first magnetic drive module is prepared by using a first photoresist containing magnetic particles, and the second magnetic drive module is prepared by using a second photoresist containing magnetic particles, wherein the coercive force of the first magnetic drive module is greater than the coercive force of the second magnetic drive module;

[0009] The first magnetic drive module and the second magnetic drive module are used to perform in-situ re-editing after applying the first magnetic field and the second magnetic field in sequence, wherein the first magnetic field is used to align the first magnetic drive module and the second magnetic drive module with the direction of the first magnetic field, and the second magnetic field is used to perform in-situ re-editing of the first magnetic drive module and the second magnetic drive module, the intensity of the first magnetic field is less than the coercive force of the second magnetic drive module, the intensity of the second magnetic field is greater than the coercive force of the second magnetic drive module and less than the coercive force of the first magnetic drive module, and the direction of the second magnetic field is opposite to the direction of the first magnetic field.

[0010] Preferably, the first magnetic driving module is prepared by using SU-8 photoresist containing nickel nanowires with a diameter of 70 nm, and the second magnetic driving module is prepared by using SU-8 photoresist containing nickel nanowires with a diameter of 200 nm.

[0011] Preferably, the second magnetic field is a uniform magnetic field of 18 mT to 36 mT.

[0012] Preferably, the first magnetic field is a uniform magnetic field of 15 mT, and the second magnetic field is a uniform magnetic field of 33 mT.

[0013] Preferably, the flexible hinge layer is prepared from poly-N-isopropylacrylamide.

[0014] As another aspect of the present invention, a method for preparing and editing a magnetic micro-nano robot with in situ re-editing capability is provided, comprising:

[0015] Step 1: Prepare the substrate layer;

[0016] Step 2, spin coating a water-soluble sacrificial layer on the substrate, and drying to remove moisture in the water-soluble sacrificial layer;

[0017] Step 3, spin coating a flexible hinge layer on the surface of the water-soluble sacrificial layer, and patterning the flexible hinge layer;

[0018] Step 4, continue to spin-coat the first magnetic particle-containing photoresist, place the silicon wafer in a uniform magnetic field and heat it at 65°C for 3 minutes, heat it to 95°C for 6 minutes, and perform a patterning process; spin-coat the second magnetic particle-containing photoresist, place the silicon wafer in a uniform magnetic field and heat it at 65°C for 3 minutes, heat it to 95°C for 6 minutes, and perform a patterning process;

[0019] Step 5: remove the sacrificial layer and release the micro-nano robot;

[0020] Step 6: Applying a magnetic field greater than that of the nickel nanowire can re-edit the magnetization of the micro-nano robot;

[0021] Step 7: Use an oscillating magnetic field to control the micro-nano robot to perform deformation movement.

[0022] Preferably, the substrate material in step 1 is a silicon wafer;

[0023] Preferably, the sacrificial layer is prepared by spin coating technology with 5% polyvinyl alcohol, the solvent is deionized water, and a coater is used for the spin coating.

[0024] Preferably, in step 3, the flexible hinge layer is poly-N-isopropylacrylamide, the patterning process adopts photolithography technology, and chloroform is used for development.

[0025] Preferably, the first photoresist containing magnetic particles in step 4 is a SU-8 photoresist containing nickel nanowires with a diameter of 70 nm, and the second photoresist containing magnetic particles in step 4 is a SU-8 photoresist containing nickel nanowires with a diameter of 200 nm.

[0026] Preferably, the heating in the uniform magnetic field in step 4 is implemented using a device consisting of a Halbach array and a cylindrical heating stage embedded therein, wherein the Halbach array provides a uniform magnetic field higher than 300 mT, and the cylindrical heating stage provides a heating temperature within 300°C.

[0027] Preferably, the specific method for removing the sacrificial layer in step 5 is to immerse the patterned silicon wafer in deionized water and release the micro-nano robot into a glass sample tank or a silicon wafer sample tank.

[0028] Preferably, the second magnetic field in step 6 is controlled by a 3D Helmholtz coil, and the magnetization magnetic field range is 18 mT to 36 mT.

[0029] Preferably, step 6 is to first apply a first magnetic field of 15mT to the micro-nano robot so that the first magnetic drive module and the second magnetic drive module of the micro-nano robot are aligned with the direction of the first magnetic field, and then apply a second magnetic field of 33mT with an excitation time less than or equal to 10ms to the micro-nano robot for magnetization.

[0030] Preferably, the vibrating magnetic field in step 7 is controlled by a 3D Helmholtz coil, and the applied magnetic field is lower than 18 mT.

[0031] Preferably, the pattern of the flexible hinge layer prepared from poly-N-isopropylacrylamide is a rectangle, and the side length of the pattern is 100 μm to 550 μm.

[0032] Preferably, the pattern of the first driving module prepared by SU-8 photoresist containing nickel nanowires with a diameter of 70nm is a square with a side length of 100μm to 200μm, and the pattern of the second driving module prepared by SU-8 photoresist containing nickel nanowires with a diameter of 200nm is a square with a side length of 100μm to 200μm.

[0033] The present invention adopts the principle of photolithography and three-layer overlay to prepare a magnetic micro-nano robot with in-situ re-editing capability. A water-soluble sacrificial layer is used to separate the micro-nano robot from a silicon wafer and release it into a liquid environment. The micro-nano robot is re-edited and magnetized in two steps. First, a smaller first magnetic field is applied to align the two magnetic drive modules with the magnetic field direction of the first magnetic field. Then, a second magnetic field with a larger opposite direction is applied to magnetize the two magnetic drive modules to achieve in-situ re-editing of the micro-nano robot. The present invention encodes multiple shape deformation instructions into the micro-nano robot by programming the magnetic configuration of the single-domain nano-magnet array on the connection panel. This programming is achieved by applying a specific sequence of magnetic fields to a nano-magnet with an appropriately customized switching field. Then, a specific shape transformation of the customized micro-nano robot can be achieved by a simple external magnetic field, that is, re-editing. The problem that the existing motion mode is still relatively rigid is solved, more motion modes are provided, and flexibility is further improved. The motion mode can be adjusted by in-situ re-editing to enhance the adaptability and flexibility of the micro-nano robot in the actual working environment. Based on these characteristics, the micro-nano robot can be used to overcome various complex environments in the human body in the future to achieve precision treatment.

[0034] In addition, the present invention is compatible with semiconductor manufacturing processes, and can add functional layers as needed, such as using a coating process to add a metal layer to enhance conductivity, and has flexible structural designability, and the shape of the micro-nano robot can be flexibly designed by drawing a mask. While simplifying the magnetically editable micro-nano robot using a photolithography process, the size of the micro-nano robot is further reduced, the mask line width accuracy can reach 5μm, and the ultraviolet wavelength is below 400nm. If the length of the nickel nanowire is shortened, the size of the magnetically editable micro-nano robot can be further reduced.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] 1. The present invention adopts the photolithography method for preparation, which is simple, environmentally friendly, and easy to operate. The prepared micro-nano robot is small in size and can be mass-produced;

[0037] 2. The present invention mixes nickel nanowires with SU-8, ingeniously utilizes the heating and curing process of SU-8, applies a uniform magnetic field to magnetize the nickel nanowires, and orients the nickel nanowires after SU-8 is completely cured. The nickel nanowires are mixed with photoresist to wrap them inside, thereby reducing the impact of the environment on the nickel nanowires, enhancing their stability, and also reducing the impact of the nickel nanowires on the biological environment during actual application;

[0038] 3. The polyvinyl alcohol, poly-N-isopropylacrylamide and SU-8 used in the present invention as components of the micro-nano robot are all biocompatible, and the nickel nanowires are wrapped inside the SU-8 and can be directly used in biological experiments;

[0039] 4. In the process of re-editing the micro-nano robot, the present invention first uses a small magnetic field to deflect the micro-nano robot to orient it, and then applies a large magnetic field for magnetization, ensuring that the magnetic field inside the micro-nano robot is exactly opposite to the direction of the magnetic field, which can effectively magnetize the nickel nanowires, thereby realizing the re-editing of the micro-nano robot by simply applying an external magnetic field, and providing more motion modes, solving the problem that the existing motion modes are still relatively rigid, and further improving flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] 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.

[0041] Figure 1 A schematic diagram of the steps of the method for preparing a magnetic micro-nano robot with in situ reprogramming capability provided by the present invention;

[0042] Figure 2 A schematic diagram of a device for curing SU-8 photoresist and magnetizing nickel nanowires provided by the present invention;

[0043] Figure 3a A schematic diagram of an array of magnetic micro-nano robots with in situ re-editing capabilities prepared by the present invention;

[0044] Figure 3b A schematic diagram of a single magnetic micro-nano robot with in situ re-editing capability prepared by the present invention;

[0045] Figure 3c Schematic diagram of a single micro-nano robot released into water;

[0046] Figure 4aA schematic diagram of an in-situ re-editing process in which the magnetization directions of the first magnetic drive module and the second magnetic drive module of the magnetic micro-nano robot with in-situ re-editing capability prepared by the present invention are changed from the same direction to the opposite direction;

[0047] Figure 4b A schematic diagram of the in-situ re-editing process of changing the magnetization directions of the first magnetic drive module and the second magnetic drive module of the magnetic micro-nano robot with in-situ re-editing capability prepared by the present invention from opposite magnetization to the same direction;

[0048] Figure 5a A schematic diagram of the internal magnetism of the micro-nano robot when the first magnetic drive module and the second magnetic drive module of the magnetic micro-nano robot with in-situ reprogramming capability prepared by the present invention are in the same direction;

[0049] Figure 5b A schematic diagram of the deformation of the micro-nano robot in response to an oscillating magnetic field when the first magnetic drive module and the second magnetic drive module of the magnetic micro-nano robot with in-situ reprogramming capability prepared by the present invention are in the same direction;

[0050] Figure 5c A schematic diagram of the internal magnetism of the micro-nano robot with in-situ reprogramming capability prepared by the present invention when the first magnetic drive module and the second magnetic drive module are in reverse directions;

[0051] Figure 5d A schematic diagram of the deformation of the micro-nano robot in response to an oscillating magnetic field when the first magnetic drive module and the second magnetic drive module of the magnetic micro-nano robot with in-situ reprogramming capability prepared by the present invention are in reverse directions;

[0052] Numbers in the figure: 1-substrate layer, 2-water-soluble sacrificial layer, 3-flexible hinge layer, 4-first magnetic drive module, 5-second magnetic drive module. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0054] Embodiment 1:

[0055] The embodiment of the present invention provides a magnetic micro-nano robot with in-situ reprogramming capability, comprising a magnetic drive layer and a flexible hinge layer, wherein the magnetic drive layer comprises a first magnetic drive module and a second magnetic drive module, and the first magnetic drive module and the second magnetic drive module are connected via the flexible hinge layer;

[0056] The first magnetic drive module is SU-8 photoresist containing nickel nanowires with a diameter of 70 nm, the second magnetic drive module is SU-8 photoresist containing nickel nanowires with a diameter of 200 nm, and the flexible hinge layer is poly-N-isopropylacrylamide, wherein the coercive force of the nickel nanowires in the first magnetic drive module is 74 mT, and the coercive force of the nickel nanowires in the second magnetic drive module is 18 mT;

[0057] The first magnetic drive module and the second magnetic drive module are used to perform in-situ re-editing after applying a first magnetic field of 15mT and a second magnetic field of 33mT in sequence. Specifically, the first magnetic field is used to align the first magnetic drive module and the second magnetic drive module with the direction of the first magnetic field. Then, the second magnetic field will prompt the robot to turn so that it is aligned with the second magnetic field in the opposite direction. However, since the nickel nanowires with a diameter of 200nm have a small coercive force and are easy to magnetize, they will be magnetized before the robot has time to completely turn around. The magnetization directions of the two nickel nanowires are opposite, and finally the in-situ re-editing of the robot is achieved.

[0058] The magnetic micro-nano robot with in situ re-editing capability provided by the embodiment of the present invention is small in size, has a simple preparation process and can be repeatedly edited by applying a magnetic field. It is very simple to operate and has more motion modes, which solves the problem that the motion modes of existing micro-nano robots are still relatively rigid, further improves the flexibility of micro-nano robots, and has broad application prospects in the biomedical field.

[0059] Embodiment 2:

[0060] This embodiment provides a method for preparing a magnetic micro-nano robot with in situ reprogramming capability, see Figure 1 ,include:

[0061] (a) A silicon wafer is used as the substrate layer 1. The water-soluble sacrificial layer 2 is 5% polyvinyl alcohol, which is spin-coated on the substrate surface by a coating machine to form a thin film at a spin coating speed of 1500 rpm / min and a thickness of about 2 μm. After spin coating, a 95° C. heating table is used to dry the water in the polyvinyl alcohol.

[0062] (b) 15 mg / ml poly-N-isopropylacrylamide was spin-coated on the surface of the sacrificial layer using a coater. The spin coating speed was 1500 rpm / min and the thickness was about 100 nm. The poly-N-isopropylacrylamide was patterned using a masked UV lithography machine with an exposure time of 360 s. After completion, it was developed with chloroform for 1 min to obtain a flexible hinge layer 3 with a square pattern.

[0063] (c) SU-8 photoresist uniformly mixed with 70 nm diameter nickel nanowires is spin-coated on the flexible hinge layer 3 using a coating machine, with a nickel nanowire mass fraction of 2%, a spin coating speed of 4000 rpm / min, and a thickness of about 30 μm. While heat curing the SU-8, the nickel nanowire array is magnetized using a Halbach array.

[0064] (d) Using an overlay process to pattern the SU-8 containing nickel nanowires with a diameter of 70 nm, the SU-8 is placed just on one side of the poly-N-isopropylacrylamide pattern, and then exposed after alignment for 18 seconds. After completion, the first magnetic drive module 4 is obtained by development.

[0065] (e) SU-8 photoresist uniformly mixed with 200 nm diameter nickel nanowires is spin-coated on the flexible hinge layer 3 using a coating machine, the nickel nanowire mass fraction is 2%, the spin coating speed is 4000 rpm / min, and the thickness is about 30 μm. While heat curing SU-8, the nickel nanowire array is magnetized using a Halbach array.

[0066] (f) Using an overlay process to pattern the SU-8 containing nickel nanowires with a diameter of 200 nm, the SU-8 is placed just on the other side of the poly-N-isopropylacrylamide pattern, and then exposure is performed after alignment for 18 seconds. After completion, development is performed to obtain the second magnetic drive module 5. Finally, a magnetically editable micro-nano robot containing two magnetic drive modules connected by a flexible hinge is obtained.

[0067] (g) The silicon wafer is immersed in water for about 3 minutes. The sacrificial layer is completely dissolved in the water, and the robot falls off the substrate. A pipette is used to move a single micro-nano robot to a glass sample tank and then into a Helmholtz coil for driving and observation.

[0068] Embodiment 3:

[0069] The embodiment of the present invention provides a device for curing SU-8 photoresist containing nickel nanowires and magnetizing the nickel nanowires, such as Figure 2 As shown, it is specifically composed of a Halbach array and a heating stage.

[0070] In this embodiment, the Halbach array is a ring, on which eight cube-shaped NdFeB permanent magnets are evenly and equidistantly embedded. Figure 2 The arrows drawn in the figure are in the same direction. The eight magnets enhance the magnetic field strength in the direction of the arrow in the center of the ring, offsetting the magnetic field strength in all other directions, and finally forming a unidirectional uniform magnetic field in the direction of the arrow in the center of the Halbach array. The array can generate a constant unidirectional static uniform magnetic field of more than 300mT in the center without the need for other energy field driving.

[0071] The heating table is mainly composed of a power supply, a control panel and a cylindrical heating table body. The control panel can set the heating temperature below 300°C. The cylindrical heating table only generates heat on a single table surface, and its size is adapted to the hollow structure of the Halbach array, so it can be embedded in the center of the Halbach array, so that the SU-8 photoresist can be heated and cured while the nickel nanowires therein can be magnetized.

[0072] In addition, there are four channels behind the Halbach array. The function of the channels is to introduce the wires of the heating platform so that the Halbach array can remain stable after being introduced into the heating platform without affecting the direction of the magnetic field. At the same time, opening four directions can flexibly configure the lead direction of the heating platform and configure terrains with different conditions.

[0073] Embodiment 4:

[0074] The morphological characterization of the magnetic micro-nano robot with in situ reprogramming capability provided by the embodiment of the present invention is as follows Figure 3a to Figure 3c As shown, specifically:

[0075] like Figure 3a As shown, the ultraviolet lithography technology is used to prepare micro-nano robots. On a 1.5x1.5 cm silicon wafer, 8x8 micro-nano robots, a total of 64 micro-nano robots, can be prepared at a time to form an array. Moreover, through the design of the mask, a variety of different types of micro-nano robots can be prepared at a time. Figure 3a Shown is a micro-nano robot with a magnetic drive module size of 100x100μm and a flexible hinge length ranging from 25μm to 100μm.

[0076] A single micro-nano robot Figure 3b As shown, due to the transparent nature of SU-8, the nickel nanowires inside it are clearly visible, the nanowires magnetized by the device in Example 3 are neatly arranged, and the addition of nickel nanowires does not affect the photolithographic properties of SU-8, and its edges are sharp.

[0077] like Figure 3c As shown, the micro-nano robot released into the water changes very little compared to the micro-nano robot that is not released, and there is no obvious deformation during long-term use, and the properties are stable.

[0078] Embodiment 5:

[0079] The embodiment of the present invention provides an editing method for a magnetic micro-nano robot with in-situ re-editing capability. Since the present invention uses a nickel nanowire with a diameter of 200nm and a length of 10μm and a nickel nanowire with a diameter of 70nm and a length of 10μm as the magnetic response materials in the second magnetic drive module and the first magnetic drive module, respectively, and their coercive forces are 18mT and 74mT, respectively, after the two nanowires are magnetized to the same direction, when a 33mT reverse magnetic field is applied to the magnetic robot, the robot will turn to align with the reverse magnetic field, but since the nickel nanowire with a diameter of 200nm has a small coercive force and is easy to magnetize, it will be magnetized before the robot has time to completely turn around, and the magnetization directions of the two nickel nanowires are opposite, and finally the in-situ re-editing of the robot is achieved. The details are as follows:

[0080] (a) If Figure 4a As shown, for a micro-nano robot in which the magnetic drive modules on both sides of the flexible hinge have the same magnetization direction in the initial state, the robot naturally stretches out in the shape of a letter "I" when no magnetic field is applied. Since the coercive force of the nickel nanowire with a diameter of 70 nm used in the embodiment of the present invention is 74 mT, and the coercive force of the nickel nanowire with a diameter of 200 nm is 18 mT, the robot still presents the shape of a letter "I" after a uniform magnetic field of 15 mT is applied thereto. Then, a reverse magnetic field of 33 mT with a change rate of less than 10 ms is applied thereto and remains unchanged after reaching the maximum value. The side containing the nanowire with a smaller coercive force, i.e., the second magnetic drive module, is magnetized to the opposite direction within 10 ms, while the side containing the nanowire with a larger coercive force, i.e., the first magnetic drive module, will not be magnetized. The magnetic drive modules on both sides of the micro-nano robot change to the opposite direction. Since the magnetic field of 33 mT is still in effect, the micro-nano robot is folded into a "V" shape. After the magnetic field is removed, the micro-nano robot returns to the shape of a letter "I".

[0081] (b) If Figure 4b As shown, for a micro-nano robot in which the magnetic drive modules on both sides of the flexible hinge have opposite magnetization directions in the initial state, the robot naturally stretches out in the shape of a straight line when no magnetic field is applied, and becomes a "V" shape after a uniform magnetic field of 15mT is applied. Then, a 33mT reverse magnetic field with a change rate of less than 10ms is applied to it and remains unchanged after reaching the maximum value. The side containing the nanowires with smaller coercive force, i.e., the second magnetic drive module, is magnetized to the opposite direction within 10ms, while the side containing the nanowires with larger coercive force, i.e., the first magnetic drive module, will not be magnetized. The magnetic blocks on both sides of the micro-nano robot change to the same direction. Since the magnetic field of 33mT is still acting, the micro-nano robot changes into the shape of a straight line. After the magnetic field is removed, the micro-nano robot maintains the "straight line" in a naturally stretched state.

[0082] (c) The 3D Helmholtz coil applies an oscillating magnetic field to control the deformation movement of the micro-nano robot, and the applied oscillating magnetic field is less than 18mT.

[0083] Embodiment 6:

[0084] The deformation changes of the magnetic micro-nano robot with in situ reprogramming capability provided by the embodiment of the present invention are as follows: Figure 5a to Figure 5d As shown, specifically:

[0085] (a) For a micro-nano robot with the same magnetization direction of the magnetic drive modules on both sides of the flexible hinge, the robot naturally stretches out in the shape of a straight line when no magnetic field is applied. When an oscillating magnetic field with an amplitude of 10 mT is applied to it, the micro-nano robot responds to the oscillating magnetic field as a whole because the magnetic drive modules have the same magnetization direction. There is no relative motion inside the robot, and the robot as a whole always flips back and forth in the shape of a straight line along the direction of the magnetic field.

[0086] (b) For a micro-nano robot whose magnetic drive modules on both sides of the flexible hinge have opposite magnetization directions, the robot naturally stretches out in an "I" shape when no magnetic field is applied. When an oscillating magnetic field with an amplitude of 10mT is applied to it, due to the opposite magnetization directions of the magnetic drive modules, the two sides of the flexible hinge inside the micro-nano robot move relative to each other, the flexible hinge deforms, and the robot folds along the direction of the oscillating magnetic field like a butterfly flapping its wings.

[0087] Some steps in the embodiments of the present invention may be implemented using software, and the corresponding software program may be stored in a readable storage medium, such as a CD or a hard disk.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetic micro-nano robot with in situ reprogramming capability, characterized in that: The invention comprises a magnetic drive layer and a flexible hinge layer, wherein the magnetic drive layer comprises a first magnetic drive module and a second magnetic drive module, and the first magnetic drive module and the second magnetic drive module are connected via the flexible hinge layer; The first magnetic drive module is prepared by using a first photoresist containing magnetic particles, and the second magnetic drive module is prepared by using a second photoresist containing magnetic particles, wherein the coercive force of the first magnetic drive module is greater than the coercive force of the second magnetic drive module; The first magnetic drive module and the second magnetic drive module are used to perform in-situ re-editing after applying a first magnetic field and a second magnetic field in sequence, wherein the first magnetic field is used to align the first magnetic drive module and the second magnetic drive module with the direction of the first magnetic field, and the second magnetic field is used to perform in-situ re-editing of the first magnetic drive module and the second magnetic drive module, the intensity of the first magnetic field is less than the coercive force of the second magnetic drive module, the intensity of the second magnetic field is greater than the coercive force of the second magnetic drive module and less than the coercive force of the first magnetic drive module, and the direction of the second magnetic field is opposite to the direction of the first magnetic field.

2. A magnetic micro-nano robot with in situ reprogramming capability according to claim 1, characterized in that: The first magnetic drive module is prepared by using SU-8 photoresist containing nickel nanowires with a diameter of 70 nm, and the second magnetic drive module is prepared by using SU-8 photoresist containing nickel nanowires with a diameter of 200 nm.

3. The magnetic micro-nano robot with in situ reprogramming capability according to claim 2, characterized in that: The second magnetic field is a uniform magnetic field of 18 mT to 36 mT.

4. The magnetic micro-nano robot with in situ reprogramming capability according to claim 3, characterized in that: The first magnetic field is a uniform magnetic field of 15 mT, and the second magnetic field is a uniform magnetic field of 33 mT.

5. The magnetic micro-nano robot with in situ reprogramming capability according to claim 1, characterized in that: The flexible hinge layer is prepared by poly-N-isopropylacrylamide.

6. A method for preparing a magnetic micro-nano robot with in situ re-editing capability and editing method, used to prepare a magnetic micro-nano robot with in situ re-editing capability as claimed in any one of claims 1 to 5, characterized in that: The method comprises: Step 1: Prepare the substrate layer; Step 2, spin coating a water-soluble sacrificial layer on the substrate layer, and drying to remove moisture from the water-soluble sacrificial layer; Step 3, spin coating a flexible hinge layer on the surface of the water-soluble sacrificial layer, and patterning the flexible hinge layer; Step 4: Spin-coat a first photoresist containing magnetic particles on the surface of the flexible hinge layer, heat and cure it in a uniform magnetic field, and perform a patterning process to obtain a first magnetic drive module; Spin-coat a second photoresist containing magnetic particles on the surface of the flexible hinge layer, heat and cure it in a uniform magnetic field, and perform a patterning process to obtain a second magnetic drive module, and obtain a magnetic drive layer, wherein the coercive force of the first magnetic drive module is greater than the coercive force of the second magnetic drive module; Step 5: remove the sacrificial layer and release the micro-nano robot; Step 6: applying a first magnetic field to the micro-nano robot so that the first magnetic drive module and the second magnetic drive module are aligned with the direction of the first magnetic field, and then applying a second magnetic field to the micro-nano robot to perform in-situ reprogramming of the first magnetic drive module and the second magnetic drive module, wherein the intensity of the first magnetic field is less than the coercive force of the second magnetic drive module, the intensity of the second magnetic field is greater than the coercive force of the second magnetic drive module and less than the coercive force of the first magnetic drive module, and the direction of the second magnetic field is opposite to that of the first magnetic field; Step 7: Use an oscillating magnetic field to control the micro-nano robot to perform deformation movement.

7. The method according to claim 6, characterized in that The water-soluble sacrificial layer is prepared by using 5% polyvinyl alcohol, and the solvent is deionized water.

8. The method according to claim 6, characterized in that In the step 4, the first magnetic particle-containing photoresist is spin-coated on the surface of the flexible hinge layer, heated and cured in a uniform magnetic field, and patterned to obtain the first magnetic driving module: SU-8 photoresist containing nickel nanowires with a diameter of 70 nm is spin-coated on the surface of the flexible hinge layer, heated and cured in a uniform magnetic field, and the SU-8 photoresist containing nickel nanowires with a diameter of 70 nm is patterned using an overlay process, so that the SU-8 photoresist containing nickel nanowires with a diameter of 70 nm is on one side of the flexible hinge layer, and then exposed and developed; In the step 4, a second photoresist containing magnetic particles is spin-coated on the surface of the flexible hinge layer, heated and cured in a uniform magnetic field, and patterned to obtain a second magnetic drive module: SU-8 photoresist containing nickel nanowires with a diameter of 200 nm is spin-coated on the surface of the flexible hinge layer, heated and cured in a uniform magnetic field, and the SU-8 photoresist containing nickel nanowires with a diameter of 200 nm is patterned using an overlay process, so that the SU-8 photoresist containing nickel nanowires with a diameter of 200 nm is on the other side of the flexible hinge layer, and then exposed and developed.

9. The method according to claim 7, characterized in that: In step 4, heating and curing in a uniform magnetic field refers to heating and curing the SU-8 photoresist on a heating platform at the center of the Halbach array and magnetizing the nickel nanowires through the Halbach array, wherein the Halbach array is used to generate a unidirectional static uniform magnetic field greater than 300mT at the center, and the heating platform is used to provide a heating temperature within 300°C.

10. The method according to claim 9, characterized in that In step 7, the oscillating magnetic field is controlled by a 3D Helmholtz coil, and the intensity of the oscillating magnetic field is smaller than the coercive force of the second magnetic drive module.

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