Magnetic microrobot and preparation method thereof

Abstract

The application relates to the technical field of micro robots, in particular to a magnetic micro robot and a preparation method thereof, and comprises the following steps: dropping a magnetic mixed photoresist on the surface of a printed micro robot, placing the micro robot in an environment with a temperature of 70-90 DEG C and standing for 3-8 min, then standing at normal temperature for 50-70 min, and obtaining the magnetic micro robot after development; wherein the magnetic mixed photoresist comprises a photoresist and magnetic particles, and the micro robot is obtained by printing through a femtosecond laser direct writing instrument. The preparation method of the magnetic micro robot has the advantages of low preparation cost, short processing time, stable magnetic field control effect, fast response time and the like, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of microrobot technology, and in particular to a magnetic microrobot and its fabrication method. Background Technology

[0002] Microrobots refer to tiny robots with a scale of micro-nano (a few nanometers to hundreds of micrometers). They have significant advantages in solving the assembly and utilization problems of molecular-sized devices and have become a rapidly developing interdisciplinary field. Based on their small size and ability to perform three-dimensional controlled motion, microrobots have applications in medicine such as the identification of tiny targets within the body, targeted drug delivery, and minimally invasive surgery.

[0003] Due to their tiny size, microrobots move in environments with very low Reynolds coefficients. These environments can be considered as highly viscous, minute, and slow-moving, where viscous forces dominate and inertial forces are negligible. Under these conditions, a continuous power source is required to drive microrobots. Magnetic field-driven microrobots, with their low required magnetic field strength and the ability of low-frequency magnetic fields to penetrate biological tissue without harming organisms, have attracted increasing attention from scientists and represent a very promising type of microrobot.

[0004] Currently, the fabrication of magnetic microrobots mainly involves depositing magnetic materials onto the surface of helical robots via sputtering or directly fabricating them through a hybrid method. However, sputtering only allows for magnetic particles to adhere to a thickness of about 200 nm on the microrobot surface, resulting in a relatively weak magnetic field. Furthermore, sputtering requires sophisticated instruments and target materials, making it difficult to mass-produce magnetic microrobots. The hybrid method, limited by femtosecond laser printing technology, struggles to guarantee a sufficient number of magnetic particles. Additionally, the presence of magnetic particles during printing easily leads to uneven surfaces on the microrobots, and the exposed photoresist results in high viscosity, further restricting its applications.

[0005] In view of this, the present invention proposes a novel method for fabricating magnetic microrobots. Summary of the Invention

[0006] The purpose of this invention is to provide a magnetic microrobot and its preparation method. The magnetic microrobot prepared by this method has the advantages of fast response and stable motion under the control of an external magnetic field, providing a good prerequisite for the motion control of magnetic microrobots.

[0007] This invention provides a method for fabricating a magnetic microrobot, comprising the following steps:

[0008] The magnetic hybrid photoresist is drop-coated onto the surface of the printed microrobot, placed in an environment of 70-90℃ for 3-8 minutes, and then placed at room temperature for 50-70 minutes. After development, a magnetic microrobot is obtained. The magnetic hybrid photoresist includes photoresist and magnetic particles. The microrobot is printed using a femtosecond laser direct writing instrument.

[0009] This invention utilizes a two-photon femtosecond laser direct-write technique to print a microrobot with a highly adhesive surface. By leveraging the viscosity of the microrobot surface and the adsorption effect of the wall surface on microparticles, magnetic particles near the microrobot are gradually adsorbed by the wall surface. When the magnetically mixed photoresist is dropped onto the surface of the microrobot, the magnetic particles quickly concentrate near the microrobot and begin to adhere, gradually stabilizing. The entire adhesion process takes only about 1 hour. Furthermore, the magnetic particles adhere stably and uniformly to the surface of the microrobot, which is crucial for the stable movement of the magnetic microrobot in an external magnetic field. This invention effectively solves the problems of high requirements for instruments and targets in sputtering methods, making it difficult to mass-produce magnetic microrobots, and the uneven surface of microrobots caused by hybrid printing technology. It provides excellent preconditions for the motion control of magnetically controlled microrobots.

[0010] As a preferred embodiment of this technical solution, to fully improve the uniformity and stability of the magnetic hybrid photoresist, during its preparation, the photoresist and magnetic particles are first mixed evenly, then a volatile organic solvent is added for further dispersion, and finally the mixture is placed in a vortex mixer and shaken for 5-10 minutes. The present invention does not strictly limit the type of volatile organic solvent; hexane, ethanol, etc., can be selected.

[0011] Furthermore, in order to increase the attachment area and obtain a better spiral motion structure, the microrobot of the present invention is preferably a spiral microrobot, and the structure of the microrobot is designed as a spiral sheet during the printing process.

[0012] As a preferred embodiment of this technical solution, the mass of magnetic particles corresponding to each 1 mL of photoresist is 2-6 mg, which ensures uniform dispersion of magnetic particles while increasing the loading capacity on the surface of the microrobot.

[0013] As a preferred embodiment of this technical solution, the magnetic particles used in this invention include any one or more of iron tetroxide, nickel, cobalt, and neodymium iron boron; and the photoresist is a negative photoresist, preferably the IP-S photoresist developed by Nanoscribe.

[0014] As a preferred embodiment of this technical solution, the particle size of the magnetic particles is 40-60 nm.

[0015] As a preferred embodiment of this technical solution, the following steps are included:

[0016] Printing the model: The print file generated by slicing the model is entered into a two-photon femtosecond laser direct writing instrument for printing;

[0017] Development: After printing, the patch is removed and immersed in PGMEA solution and isopropanol solution in turn. Finally, it is taken out and air-dried to obtain a spiral-shaped micro robot.

[0018] Attaching magnetic particles: The magnetic photoresist is drop-coated onto the surface of the spiral microrobot, placed in an environment of 70-90℃ for 3-8 minutes, and then placed at room temperature for 50-70 minutes. After development, the magnetic microrobot is obtained.

[0019] In the photolithography process, IP-S photoresist is coated onto the substrate surface, and a femtosecond laser is used to locally polymerize it at the desired locations to form the required structure and pattern. Then, a development solution is used to remove the unpolymerized portions, leaving the polymerized structure and pattern. In negative photoresist, the unpolymerized portions are removed, while the polymerized portions are retained. Next, a drop of pre-prepared magnetic hybrid photoresist is placed on the prepared microrobot and allowed to stand at 70-90℃ for 3-8 minutes, followed by standing at room temperature for 50-70 minutes. After development, the magnetic microrobot is obtained.

[0020] The preferred conditions for adhesion are: standing at 80°C for 5 minutes, and then standing at room temperature for 60 minutes.

[0021] As a preferred embodiment of this technical solution, the size of the model is 100-1000μm.

[0022] As a preferred embodiment of this technical solution, during development, the sample is immersed in PGMEA solution for 10-30 minutes and in isopropanol for 2-10 minutes.

[0023] Secondly, the present invention also discloses a magnetic microrobot prepared by the above-mentioned preparation method, which should also fall within the protection scope of the present invention.

[0024] The method for fabricating the magnetic microrobot of the present invention has at least the following technical advantages:

[0025] This invention utilizes a two-photon femtosecond laser direct writing instrument to print a microrobot surface with high viscosity. By leveraging the viscosity of the microrobot surface and the adsorption effect of the wall surface on microparticles, magnetic particles near the microrobot are gradually adsorbed by the wall surface. After the magnetic hybrid photoresist is dropped onto the surface of the microrobot, it is first placed in an environment of 70-90℃ for 3-8 minutes. During this time, the viscosity of the magnetic hybrid photoresist decreases, its fluidity increases, and magnetic particles quickly concentrate near the microrobot and begin to adhere. Then, it is placed in a room temperature environment to allow the adhesion effect to gradually stabilize. The entire adhesion process takes only about 1 hour, and the magnetic particles can be stably and uniformly adhered to the surface of the microrobot. Therefore, the method for fabricating magnetic microrobots of this invention has advantages such as low fabrication cost, short processing time, stable magnetic field control, and fast response time, and has broad application prospects. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a printed model of the miniature robot of the present invention;

[0028] Figure 2 In this invention, photoresist is applied to the center of the patch.

[0029] Figure 3 The structure of the microrobot fabricated by the femtosecond laser method of this invention (observed under a microscope);

[0030] Figure 4 This invention describes the process of heating and attaching magnetic hybrid photoresist to the surface of a microrobot.

[0031] Figure 5 The structure of the magnetic microrobot of this invention (observed under a microscope);

[0032] Figure 6 The structure of the magnetic microrobot attached to the control robot of the present invention after being left to stand at 20°C for 1 hour (observed under a microscope);

[0033] Figure 7 The structure of the magnetic microrobot attached to the control robot in Comparative Example 2 of the present invention after being left to stand at 20°C for 24 hours (observed under a microscope). Detailed Implementation

[0034] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The reagents used in the following examples were sourced from:

[0038] IP-S photoresist: Nanoscribe

[0039] PGMEA: Sigma-Aldrich (Shanghai) Trading Co., Ltd., ≥99.5%;

[0040] Example 1

[0041] Preparation of magnetic hybrid photoresist

[0042] IP-S photoresist and 50nm magnetic nickel particles were mixed evenly at a ratio of 1ml:4mg. Then, volatile organic solvent n-hexane was added to ensure uniform mixing of the magnetic particles and photoresist. Finally, the mixture was placed in a vortex mixer and stirred for 5 minutes to obtain the magnetic mixed photoresist.

[0043] Example 2

[0044] Preparation of magnetic hybrid photoresist

[0045] The IP-S photoresist and magnetic iron oxide particles with a particle size of 50nm were mixed evenly at a ratio of 1ml:4mg. Then, the volatile organic solvent n-hexane was added to ensure that the magnetic particles and photoresist were evenly mixed. Finally, the mixture was stirred in a vortex mixer for 5 minutes to obtain the magnetic mixed photoresist.

[0046] Example 3

[0047] Preparation of magnetic hybrid photoresist

[0048] IP-S photoresist and 50nm magnetic cobalt particles were mixed evenly at a ratio of 1ml:4mg. Then, volatile organic solvent n-hexane was added to ensure uniform mixing of the magnetic particles and photoresist. Finally, the mixture was stirred in a vortex mixer for 5 minutes to obtain the magnetic mixed photoresist.

[0049] Example 4

[0050] Fabrication of magnetic microrobots

[0051] Model building: The structure of the micro-robot was drawn using SOLIDWORKS software, its three-dimensional model was built, and it was saved as an STL file in preparation for slicing.

[0052] Slicing: Import the STL file into the slicing software and use the slicing software to slice the 3D model. Figure 1 Input the target print size ratio, adjust various printing parameters, and output the print file;

[0053] Applying the adhesive: Use a pipette to apply one drop of IP-S photoresist to the center of the patch. Figure 2 );

[0054] Printing: Using two-photon femtosecond laser 3D printing technology, the patch holder is placed into the printer. After the printing software is initialized, the lens is opened and the objective lens is controlled to automatically approach the patch finding interface. After finding the interface, the printing file generated by the slicing software is entered and printed.

[0055] Development: After printing is complete, lower the objective lens, remove the patch holder, remove the patch, fix it with the sample holder, immerse it in PGMEA solution for 25 minutes, remove it and immerse it in isopropanol solution for 5 minutes, and finally remove it and air dry.

[0056] Observation: Place the patch under a microscope to observe whether the printed structure is complete. Figure 3 ).

[0057] Adhesion: The magnetic hybrid photoresist prepared in Example 1 was dropped onto the printed microrobot and placed on a hot plate for 5 minutes, with the temperature controlled at 80°C. Figure 4 Then, place it in an environment of about 20°C for 60 minutes, and finally, perform development again to obtain a magnetic microrobot with magnetic particles attached to its surface. Figure 5 ).

[0058] Example 5

[0059] Fabrication of magnetic microrobots

[0060] Model building: The structure of the micro-robot was drawn using SOLIDWORKS software, its three-dimensional model was built, and it was saved as an STL file in preparation for slicing.

[0061] Slicing: Import the STL file into the slicing software, use the slicing software to slice the 3D model, input the target printing size scale, adjust various printing parameters, and output the print file;

[0062] Applying the adhesive: Use a pipette to pick up a drop of IP-S photoresist and apply it to the center of the patch;

[0063] Printing: Using two-photon femtosecond laser 3D printing technology, the patch holder is placed into the printer. After the printing software is initialized, the lens is opened and the objective lens is controlled to automatically approach the patch finding interface. After finding the interface, the printing file generated by the slicing software is entered and printed.

[0064] Development: After printing is complete, lower the objective lens, remove the patch holder, remove the patch, fix it with the sample holder, immerse it in PGMEA solution for 25 minutes, remove it and immerse it in isopropanol solution for 5 minutes, and finally remove it and air dry.

[0065] Observation: Place the patch under a microscope to observe whether the printed structure is complete.

[0066] Adhesion: The magnetic hybrid photoresist prepared in Example 2 is dropped onto the printed microrobot and placed on a hot plate for 5 minutes, with the temperature controlled at 80°C. Then, it is placed in an environment of about 20°C for 60 minutes. Finally, it is developed again to obtain a magnetic microrobot with magnetic particles attached to its surface.

[0067] Example 6

[0068] Fabrication of magnetic microrobots

[0069] Model building: The structure of the micro-robot was drawn using SOLIDWORKS software, its three-dimensional model was built, and it was saved as an STL file in preparation for slicing.

[0070] Slicing: Import the STL file into the slicing software, use the slicing software to slice the 3D model, input the target printing size scale, adjust various printing parameters, and output the print file;

[0071] Applying the adhesive: Use a pipette to pick up a drop of IP-S photoresist and apply it to the center of the patch;

[0072] Printing: Using two-photon femtosecond laser 3D printing technology, the patch holder is placed into the printer. After the printing software is initialized, the lens is opened and the objective lens is controlled to automatically approach the patch finding interface. After finding the interface, the printing file generated by the slicing software is entered and printed.

[0073] Development: After printing is complete, lower the objective lens, remove the patch holder, remove the patch, fix it with the sample holder, immerse it in PGMEA solution for 25 minutes, remove it and immerse it in isopropanol solution for 5 minutes, and finally remove it and air dry.

[0074] Observation: Place the patch under a microscope to observe whether the printed structure is complete.

[0075] Adhesion: The magnetic hybrid photoresist prepared in Example 3 is dropped onto the printed microrobot and placed on a hot plate for 5 minutes, with the temperature controlled at 80°C. Then, it is placed in an environment of about 20°C for 60 minutes. Finally, it is developed again to obtain a magnetic microrobot with magnetic particles attached to its surface.

[0076] Example 7

[0077] Fabrication of magnetic microrobots

[0078] Model building: The structure of the micro-robot was drawn using SOLIDWORKS software, its three-dimensional model was built, and it was saved as an STL file in preparation for slicing.

[0079] Slicing: Import the STL file into the slicing software, use the slicing software to slice the 3D model, input the target printing size scale, adjust various printing parameters, and output the print file;

[0080] Applying the adhesive: Use a pipette to pick up a drop of IP-S photoresist and apply it to the center of the patch;

[0081] Printing: Using two-photon femtosecond laser 3D printing technology, the patch holder is placed into the printer. After the printing software is initialized, the lens is opened and the objective lens is controlled to automatically approach the patch finding interface. After finding the interface, the printing file generated by the slicing software is entered and printed.

[0082] Development: After printing is complete, lower the objective lens, remove the patch holder, remove the patch, fix it with the sample holder, immerse it in PGMEA solution for 25 minutes, remove it and immerse it in isopropanol solution for 5 minutes, and finally remove it and air dry.

[0083] Observation: Place the patch under a microscope to observe whether the printed structure is complete.

[0084] Adhesion: The magnetic hybrid photoresist prepared in Example 2 is dropped onto the printed microrobot and placed on a hot plate for 3 minutes, with the temperature controlled at 90°C. Then, it is placed in an environment of about 20°C for 60 minutes. Finally, it is developed again to obtain a magnetic microrobot with magnetic particles attached to its surface.

[0085] Example 8

[0086] Fabrication of magnetic microrobots

[0087] Model building: The structure of the micro-robot was drawn using SOLIDWORKS software, its three-dimensional model was built, and it was saved as an STL file in preparation for slicing.

[0088] Slicing: Import the STL file into the slicing software, use the slicing software to slice the 3D model, input the target printing size scale, adjust various printing parameters, and output the print file;

[0089] Applying the adhesive: Use a pipette to pick up a drop of IP-S photoresist and apply it to the center of the patch;

[0090] Printing: Using two-photon femtosecond laser 3D printing technology, the patch holder is placed into the printer. After the printing software is initialized, the lens is opened and the objective lens is controlled to automatically approach the patch finding interface. After finding the interface, the printing file generated by the slicing software is entered and printed.

[0091] Development: After printing is complete, lower the objective lens, remove the patch holder, remove the patch, fix it with the sample holder, immerse it in PGMEA solution for 25 minutes, remove it and immerse it in isopropanol solution for 5 minutes, and finally remove it and air dry.

[0092] Observation: Place the patch under a microscope to observe whether the printed structure is complete.

[0093] Adhesion: The magnetic hybrid photoresist prepared in Example 2 was dropped onto the printed microrobot and placed on a hot plate for 8 minutes, with the temperature controlled at 70°C. Then, it was placed in an environment of about 20°C for 60 minutes. Finally, it was developed again to obtain a magnetic microrobot with magnetic particles attached to its surface.

[0094] Compare with Example 1

[0095] The adhesion conditions are: stand for 1 hour at 20°C;

[0096] Everything else is basically the same as in Example 4.

[0097] Compare with Example 2

[0098] The adhesion conditions are: static adhesion at 20℃ for 24 hours;

[0099] Everything else is basically the same as in Example 4.

[0100] contrast Figure 5-7 It can be seen that, whether the magnetic particles are left to adhere at 20℃ for 1 hour or 20 hours, the number and uniformity of the magnetic particles are poor, and it is impossible to guarantee that the magnetic particles adhere uniformly and effectively.

[0101] In summary, the microrobot surface printed by the two-photon femtosecond laser direct writing instrument of this invention has a large viscosity. Utilizing the viscosity property of the microrobot surface and the adsorption effect of the wall on the microparticles, magnetic particles near the microrobot can be gradually adsorbed by the wall. After the magnetic hybrid photoresist is dropped onto the surface of the microrobot, it is first placed in an environment of 70-90℃ for 3-8 minutes. At this time, the viscosity of the magnetic hybrid photoresist decreases and the fluidity increases. Magnetic particles quickly concentrate near the microrobot and begin to adhere. Then, it is placed in a room temperature environment to allow the adhesion effect to gradually stabilize. The entire adhesion process only takes about 1 hour, and the magnetic particles can be stably and uniformly adhered to the surface of the microrobot.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for fabricating a magnetic microrobot, characterized in that, Includes the following steps: A microrobot is provided, wherein the microrobot is a spiral-shaped microrobot printed by a femtosecond laser direct writing instrument, and its surface has a large degree of adhesion; A magnetic hybrid photoresist is drop-coated onto the surface of a printed microrobot, wherein the magnetic hybrid photoresist comprises photoresist and magnetic particles; After the magnetic hybrid photoresist is drop-coated onto the surface of the spiral microrobot, it is placed in an environment of 70-90℃ and left to stand for 3-8 minutes. At this time, the viscosity of the magnetic hybrid photoresist decreases, the fluidity increases, and the magnetic particles quickly concentrate near the microrobot and begin to adhere. The microrobot is then left to stand at room temperature for 50-70 minutes to allow the magnetic particles to adhere stably and uniformly to the surface of the microrobot. After development, the magnetic microrobot is obtained.

2. The preparation method according to claim 1, characterized in that, When preparing magnetic mixed photoresist, the photoresist and magnetic particles are mixed evenly, a volatile organic solvent is added, and the mixture is shaken in a vortex mixer for 5-10 minutes.

3. The preparation method according to claim 1, characterized in that, The mass of magnetic particles corresponding to each 1 mL of photoresist is 2-6 mg.

4. The preparation method according to claim 1, characterized in that, The magnetic particles include any one or more of iron(II,III) oxide, nickel, cobalt, and neodymium iron boron. The photoresist is an IP-S photoresist.

5. The preparation method according to claim 1, characterized in that, The magnetic particles have a particle size of 40-60 nm.

6. The preparation method according to claim 1, characterized in that, Includes the following steps: Printing the model: The print file generated by slicing the model is entered into a two-photon femtosecond laser direct writing instrument for printing; Development: After printing, the patch is removed and immersed in PGMEA solution and isopropanol solution in turn. Finally, it is taken out and air-dried to obtain a spiral-shaped micro robot. Attaching magnetic particles: The magnetic photoresist is drop-coated onto the surface of the spiral microrobot, placed in an environment of 70-90℃ for 3-8 minutes, and then placed at room temperature for 50-70 minutes. After development, the magnetic microrobot is obtained.

7. The preparation method according to claim 6, characterized in that, The size of the model is 100-1000 μm.

8. The preparation method according to claim 6, characterized in that, During development, the sample is immersed in PGMEA solution for 10-30 minutes and in isopropanol for 2-10 minutes.

9. A magnetic microrobot, characterized in that, Prepared by the preparation method according to any one of claims 1-8.

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