A spiral micro robot and its preparation method and use

Abstract

The present invention relates to a spiral microrobot, a preparation method and use thereof. The spiral microrobot has a spiral angle of 15-75° and a body length of 40-1000 μm. The spiral microrobot can move under the drive of a magnetic field. The preparation method of the spiral microrobot is simple, and the prepared spiral microrobot has good consistency and high yield, and can be used for targeted drug delivery.

Description

Technical Field

[0001] The invention belongs to the field of micro-robots and relates to a spiral micro-robot and a preparation method and application thereof. Background Art

[0002] In recent years, more and more researchers have turned their attention to micro-robots. Micro-robots can enter narrow areas to assist surgeons in performing operations because of their small size. The preparation of micro-nano robots driven by chemical fuels, external electric fields, light fields, ultrasound and magnetic fields has made rapid progress in recent years. Among these different types of driving methods, magnetic field driving has attracted more and more attention from scientists because of its non-toxicity and strong operability.

[0003] Common magnetic field driving methods include rotating magnetic field driving and gradient magnetic field driving. However, gradient magnetic fields require greater magnetic field strength and lower driving efficiency, so more people place their hopes on rotating magnetic fields. When an object is reduced to a certain size, inertial force no longer plays a dominant role, and general reciprocating motion will no longer allow tiny objects to gain forward speed in liquids. Therefore, under the action of a rotating magnetic field, simple reciprocating rotational motion will not allow an object to gain a forward speed. There are two types of microorganisms in nature, one is a sperm cell with a flexible tail, and the other is a bacterium with spiral flagella. The molecular motor of this type of bacterium will drive the spiral flagella to produce rotational motion, thereby generating a forward driving force. Inspired by nature, scientists have been preparing this bionic spiral microrobot that can be driven by a rotating magnetic field.

[0004] In 2019, Dr. Zhang Li of the Swiss Federal Institute of Technology in Zurich used the lattice mismatch of different materials to generate stress to prepare this spiral three-dimensional structure (see reference: Zhang, L., et al., Artificial bacterial flagella: Fabrication and magnetic control. Applied Physics Letters, 2009.94(6): p.064107.); when preparing the spiral structure, scientists added magnetic material nickel. The magnetic head will rotate with the external rotating magnetic field, thereby driving the non-magnetic spiral tail to rotate, thereby gaining the ability to move forward.

[0005] At present, the preparation method of the spiral robot includes the following steps: first, a sacrificial layer of aluminum gallium arsenide and a double layer of indium gallium arsenide / gallium arsenide are grown on a gallium arsenide (GaAs) substrate with a crystal orientation of 001 by molecular beam epitaxy; then a chromium layer is deposited by electron beam evaporation; subsequently, the three layers of indium gallium arsenide / gallium arsenide / chromium are obtained by reactive ion etching to obtain a strip-shaped pattern; the soft magnetic head is prepared by chromium / nickel / gold layer thin film deposition and stripping process, and finally, the aluminum gallium arsenide sacrificial layer is selectively etched in a 2% hydrofluoric acid solution, and the planar strip pattern spontaneously curls up to form a spiral structure; the problem with this scheme is that the preparation steps are cumbersome, and many preparation instruments are involved. At the same time, a highly dangerous hydrofluoric acid solution needs to be used in the preparation.

[0006] At the same time, using microrobots for targeted drug delivery has high requirements for the delivery volume, but the amount of anti-cancer drugs carried on each microrobot is limited. Therefore, in order to achieve drug delivery of multiple microrobots to a tumor cell, there are very high requirements for the output of microrobots. The preparation process of the spiral microrobots currently used has low efficiency, insufficient yield, and poor product consistency.

[0007] The laser direct writing printer technology is only applicable to photosensitive materials, generally non-metallic materials and non-magnetic materials, with low printing efficiency of about 1-2 seconds per piece and high cost.

[0008] Therefore, it is still of great significance to develop a high-yield spiral microrobot and its preparation method. Summary of the invention

[0009] The object of the present invention is to provide a spiral microrobot, a preparation method and use thereof, wherein the spiral microrobot has a spiral angle of 15-75°, a body length of 40-1000 μm, and can move under the drive of a magnetic field. The preparation method of the spiral microrobot is simple, and the prepared spiral microrobot has good consistency and high yield, and can be used for targeted drug delivery.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] In the first aspect, the present invention provides a spiral microrobot, wherein the spiral angle of the spiral microrobot is 15-75°, for example, 15°, 30°, 45°, 60° or 75°, and the body length of the spiral microrobot is 40-1000μm, for example, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm or 900μm, etc.

[0012] The body length of the spiral microrobot described in the present invention can be calculated by the following method:

[0013]

[0014] Wherein, L is the body length of the spiral microrobot, θ is the helical angle of the spiral microrobot; and R is the radius of the spiral microrobot.

[0015] Preferably, the spiral microrobot is obtained by curling a long parallelogram.

[0016] Preferably, a base angle of one side of the elongated parallelogram is 15-75°, such as 15°, 30°, 45°, 60° or 75°, etc., preferably 20-40°.

[0017] The spiral microrobot of the present invention is obtained by curling a long parallelogram, and the bottom angle of one side of the long parallelogram is controlled to be 20-40 degrees. The spiral microrobot obtained thereby has higher motion performance when driven by a magnetic field.

[0018] Preferably, after the elongated parallelogram is curled, based on the long side of the elongated parallelogram, every 30-80 μm, for example, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm or 75 μm, etc., is one turn of the spiral microrobot.

[0019] Preferably, the helix angle of the helical microrobot is 20-40°, for example, 22°, 24°, 26°, 28°, 30°, 32°, 34°, 36° or 38°.

[0020] The helical angle of the spiral microrobot described in the present invention is within the above range, which is conducive to the movement of the spiral microrobot under the action of the magnetic field and improves the movement performance of the microrobot.

[0021] Preferably, the body length of the spiral microrobot is 50-400 μm, for example, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, 250 μm, 300 μm, 350 μm or 380 μm.

[0022] Preferably, the spiral microrobot is a spiral sheet structure.

[0023] Preferably, the thickness of the spiral sheet structure is 20-300 nm, such as 50 nm, 100 nm, 150 nm, 200 nm or 250 nm, etc., preferably 80-100 nm.

[0024] The spiral microrobot of the present invention is a spiral sheet structure, and the sheet thickness of the spiral sheet structure is 20-300nm. The thickness within the above range is conducive to the movement of the spiral microrobot under the drive of the magnetic field.

[0025] Preferably, the spiral microrobot is made of metal material.

[0026] Preferably, the spiral microrobot is made of ferromagnetic metal material.

[0027] Preferably, the material of the spiral microrobot is any one of nickel (Ni), titanium (Ti), cobalt (Co), copper (Cu), gold (Au), platinum (Pt), aluminum (Al), iron (Fe) or cobalt-nickel alloy (CoNi) or a combination of at least two thereof, preferably nickel.

[0028] In a second aspect, the present invention provides a method for preparing the spiral microrobot as described in the first aspect, the method comprising the following steps:

[0029] (1) forming a photoresist layer on a substrate and then baking it;

[0030] (2) printing a long parallelogram on the photoresist layer by ultraviolet exposure, followed by baking and developing; the bottom angle of one side of the long parallelogram is 15-75°;

[0031] (3) Vapor-depositing a metal material layer on the long parallelogram obtained in step (2), and then immersing it in a heated solvent to obtain the spiral microrobot.

[0032] In the preparation process of the spiral micro-robot described in the present invention, a photoresist layer with a specific pattern is formed on a substrate, and then a metal material layer is evaporated on the photoresist layer, and then it is placed in a solvent to soak and dissolve the photoresist. Due to the swelling effect of the photoresist, the metal material layer is curled. When there is a deviation between the arrangement direction and the curling direction of the pattern, the photoresist layer and the metal material layer are rolled into a spiral structure together, and then further soaked and dissolved, thereby completing the preparation of a single-layer spiral micro-robot; the preparation process of the method described in the present invention is simple and can achieve large-scale preparation.

[0033] In the preparation process of the present invention, the swelling effect of the photoresist in the solvent is used to make the photoresist and the metal material layer on its surface curl together to form a spiral structure. To achieve the above purpose, the shape of the photoresist needs to be controlled to be a long parallelogram, and the bottom angle of one side is controlled to be 15-75°.

[0034] The method for preparing the spiral microrobot of the present invention has high preparation efficiency, which can reach 5-10 per second.

[0035] Preferably, after the elongated parallelogram is curled, based on the long side of the elongated parallelogram, every 30-80 μm, for example, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm or 75 μm, etc., is one turn of the spiral microrobot.

[0036] Preferably, the substrate in step (1) comprises any one of a silicon wafer, silicon dioxide or silicon nitride.

[0037] Preferably, the photoresist of the photoresist layer in step (1) is a negative photoresist.

[0038] Preferably, the photoresist in step (1) is selected from any one of SU8, AZ nlof 2035, AZ nlof 2020, AZ nlof5510, and AZ nlof 2070.

[0039] Preferably, the thickness of the photoresist layer in step (1) is 2-8 μm, for example, 3 μm, 4 μm, 5 μm, 6 μm or 7 μm.

[0040] In the process of preparing the spiral micro-robot described in the present invention, the function of the photoresist layer is to combine a specific pattern in thickness through its swelling effect, so that the photoresist layer and the metal material layer are curled together to form a spiral shape.

[0041] During the preparation process of the spiral microrobot described in the present invention, the thickness of the photoresist layer is controlled to be 2-8μm, which is beneficial to the swelling effect of the photoresist layer in the subsequent process, so that the photoresist and the metal material layer are curled together to form a spiral structure, thereby increasing the efficiency of the preparation process; when the thickness of the photoresist layer is less than 2μm, spin coating is difficult to achieve and the accumulated swelling deformation is small and insufficient to curl the metal material layer; when the thickness of the photoresist layer is greater than 8μm, the development effect is poor and causes waste.

[0042] Preferably, the method of forming a photoresist layer on a substrate in step (1) comprises coating a photoresist on the substrate.

[0043] Preferably, the method of coating the photoresist on the substrate is spin coating.

[0044] Preferably, the rotation speed of the spin coating is 2000-4000 rpm, such as 2500 rpm, 3000 rpm or 3500 rpm.

[0045] Preferably, the spin coating time is 45-30 s, such as 32 s, 35 s, 38 s, 40 s or 43 s.

[0046] Preferably, the baking time in step (1) is 60-90 s, such as 65 s, 70 s, 75 s, 80 s or 85 s.

[0047] Preferably, the baking temperature in step (1) is 110-90°C, such as 105°C, 100°C or 95°C.

[0048] Preferably, the intensity of the ultraviolet light in the ultraviolet exposure in step (2) is 5-13 mW / cm 2 , for example 6mW / cm 2 , 7mW / cm 2 , 8mW / cm 2 , 9mW / cm 2 、10mW / cm 2 、11mW / cm 2 or 12mW / cm 2 wait.

[0049] Preferably, the ultraviolet exposure time in step (2) is 20-15 s, such as 19 s, 18 s, 17 s or 16 s.

[0050] Preferably, the base angle of one side of the elongated parallelogram in step (2) is 20-40°, such as 25°, 30°, 35° or 38°.

[0051] Preferably, the baking temperature in step (2) is 80-120°C, such as 90°C, 100°C or 110°C.

[0052] Preferably, the baking time in step (2) is 90-60 s, such as 85 s, 80 s, 75 s, 70 s or 65 s.

[0053] Preferably, the development in step (2) is carried out in a developer, and the development time is 50-70 s, such as 55 s, 60 s or 65 s.

[0054] Preferably, the developer includes any one of ZX 238, AZ326, AZ 726 or AZ 826.

[0055] Preferably, the evaporation in step (2) is electron beam evaporation.

[0056] Preferably, the deposition rate of the evaporation process in step (2) is For example or wait.

[0057] Preferably, the solvent in step (3) is any one of N-methylpyrrolidone (N-Methyl pyrrolidone, N MP), dimethyl sulfoxide (Dimethyl sulfoxide, DMSO) or acetone (acetone) or a combination of at least two thereof, preferably NMP.

[0058] Preferably, the temperature of the heated solvent in step (3) is 80-100°C, such as 75°C, 90°C or 95°C.

[0059] Preferably, the soaking process in step (3) is accompanied by ultrasonic treatment.

[0060] During the immersion process described herein, the photoresist swells, and ultrasonic treatment is beneficial to the swelling process.

[0061] Preferably, the ultrasonic treatment time is 30-120 s, such as 50 s, 70 s, 90 s or 110 s.

[0062] Preferably, the soaking time in step (3) is 3-1 days, such as 2.5 days, 2 days or 1.5 days.

[0063] Preferably, the soaking in step (3) also includes washing.

[0064] Preferably, the cleaning solution comprises alcohol and water.

[0065] Preferably, the cleaning method comprises first rinsing with alcohol and then rinsing with water.

[0066] Preferably, the alcohol comprises isopropanol and / or ethanol.

[0067] As a preferred technical solution of the present invention, the method for preparing the spiral microrobot comprises the following steps:

[0068] (a) pouring a photoresist onto a silicon wafer and spin coating the silicon wafer at a rotation speed of 2000-4000 rpm for 45-30 s to obtain a photoresist layer;

[0069] (b) baking the photoresist layer obtained in step (a) at 90-110° C. for 90-60 seconds, and then cooling to room temperature;

[0070] (c) Imprinting the designed film pattern on the photoresist layer by ultraviolet exposure, wherein the wavelength of the ultraviolet light of the ultraviolet exposure is 300-370nm, and the intensity of the ultraviolet light is 5-13mW / cm 2 , the UV exposure time is 20-15s, followed by baking at 80-120°C for 90-60s, and developing in a developer for 50-70s to obtain a photoresist in the shape of a long parallelogram;

[0071] (d) depositing a metal material on the long parallelogram-shaped photoresist obtained in step (c) by electron beam evaporation, and the deposition rate of the electron beam evaporation is A metal material layer with a thickness of 20-300 nm is obtained; then the metal material layer is immersed in N-methylpyrrolidone at a temperature of 80-100° C. for 3-1 days to obtain the spiral micro robot.

[0072] In a third aspect, the present invention provides a use of the spiral microrobot as described in the first aspect, wherein the spiral microrobot is used for targeted drug delivery.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] (1) The spiral microrobot of the present invention has a spiral angle of 15-75° and a body length of 40-1000 μm. It can move under the drive of a magnetic field and can be used as a carrier for targeted drug delivery;

[0075] (2) The preparation process of the spiral microrobot described in the present invention is simple and suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 is a schematic diagram of the structure of the spiral microrobot of the present invention;

[0077] Figure 2 It is a schematic flow chart of the preparation process of the spiral microrobot of the present invention;

[0078] Figure 3 is an optical microscope image of the spiral microrobot prepared in Example 1 of the present invention;

[0079] Figure 4 This is an optical microscope image of an intermediate product of batch preparation of spiral microrobots in Example 1 of the present invention;

[0080] Figure 5 This is an optical microscope image of the spiral microrobot prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0081] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0082] The structural schematic diagram of the spiral microrobot described in the specific implementation section is as follows Figure 1 As shown by Figure 1 It can be seen that the spiral microrobot is a spiral sheet structure, and the dimensions of its body length, radius and spiral angle are as follows: Figure 1 as shown in .

[0083] The schematic diagram of the process of preparing the spiral microrobot described in the specific implementation method is as follows Figure 2 shown by Figure 2 It can be seen that the preparation process comprises the following steps:

[0084] (a) coating a photoresist layer on the surface of a silicon wafer;

[0085] (b) drying the photoresist layer, ultraviolet exposure, drying, and developing to obtain a photoresist layer in the shape of a long parallelogram;

[0086] (c) vapor-depositing a metal material layer on the surface of the long parallelogram photoresist layer obtained in step (b), and then immersing it in N-methylpyrrolidone (NMP) to obtain the spiral microrobot.

[0087] The following Examples 1-4 all adopt the above preparation process.

[0088] Example 1

[0089] The optical microscope image of the spiral microrobot described in this embodiment is as follows: Figure 3 As shown by Figure 3 It can be seen that the helical angle of the helical microrobot is 37.5° and its body length is 120 μm.

[0090] The method for preparing the spiral microrobot comprises the following steps:

[0091] (a) 4 mL of AZ nLof 2070 commercial photoresist was poured onto a clean silicon wafer and spin-coated at a rotation speed of 3000 rpm for 35 seconds to obtain a photoresist layer with a thickness of 5 μm;

[0092] (b) baking the photoresist layer obtained in step (a) at 100° C. for 80 seconds, and then cooling it to room temperature;

[0093] (c) The designed film pattern is printed on the photoresist layer by ultraviolet exposure, the wavelength of the ultraviolet light of the ultraviolet exposure is 365nm, and the intensity of the ultraviolet light is 7.3mW / cm 2 , the UV exposure time is 18s, followed by baking at 90°C for 80s, and developing in AZ 826MIF developer for 60s to obtain a photoresist in the shape of a long parallelogram, wherein the bottom angle of one side of the long parallelogram is 37.5°, and the long side length of the long parallelogram is 300μm;

[0094] (d) depositing a Ni thin film on the long parallelogram-shaped photoresist obtained in step (c) by electron beam evaporation, and the deposition rate of the electron beam evaporation is A Ni material layer with a thickness of 100 nm was obtained; then it was immersed in N-methylpyrrolidone (NMP) at a temperature of 90° C., ultrasonically treated for 40 seconds, and then immersed for 2 days, and washed with ethanol and water to obtain the spiral microrobot.

[0095] The optical microscopic picture of the intermediate product in the process of batch preparation of spiral microrobots in this example is as follows: Figure 4 As shown by Figure 4 It can be seen that during the preparation process of this embodiment, the swelling effect of the photoresist layer drives the nickel (Ni) material layer to curl together to form a spiral structure; the method of the present invention can prepare spiral micro-robots with good consistency in large quantities.

[0096] Example 2

[0097] The optical microscope image of the spiral microrobot described in this embodiment is as follows: Figure 5 As shown by Figure 5 It can be seen that the helical angle of the helical microrobot is 29.4° and its body length is 135 μm.

[0098] The method for preparing the spiral microrobot comprises the following steps:

[0099] (a) 5 mL of AZ nLof 2070 commercial photoresist was poured onto a clean silicon wafer and spin-coated at a rotation speed of 4000 rpm for 35 seconds to obtain a photoresist layer with a thickness of 6 μm;

[0100] (b) baking the photoresist layer obtained in step (a) at 100° C. for 90 seconds, and then cooling to room temperature;

[0101] (c) The designed film pattern is printed on the photoresist layer by ultraviolet exposure, the wavelength of the ultraviolet light of the ultraviolet exposure is 365nm, and the intensity of the ultraviolet light is 7.3mW / cm 2 , the UV exposure time is 18 seconds, followed by baking at 120° C. for 60 seconds, and developing in AZ 826MIF developer for 60 seconds to obtain a photoresist in the shape of a long parallelogram, wherein the bottom angle of one side of the long parallelogram is 29.4°, and the long side length of the long parallelogram is 300 μm;

[0102] (d) depositing a Ni thin film on the long parallelogram-shaped photoresist obtained in step (c) by electron beam evaporation, and the deposition rate of the electron beam evaporation is A nickel (Ni) material layer with a thickness of 90 nm was obtained; then it was immersed in N-methylpyrrolidone (NMP) at a temperature of 100° C., ultrasonically treated for 50 seconds, and then immersed for 2 days, and washed with isopropanol and water to obtain the spiral microrobot.

[0103] Example 3

[0104] The helical angle of the helical microrobot described in this embodiment is 20°, and its body length is 40 μm.

[0105] The method for preparing the spiral microrobot comprises the following steps:

[0106] (a) 3 mL of AZ nLof 2070 commercial photoresist was poured onto a clean silicon wafer and spin-coated at a rotation speed of 4000 rpm for 30 seconds to obtain a photoresist layer with a thickness of 3 μm;

[0107] (b) baking the photoresist layer obtained in step (a) at 90° C. for 60 seconds, and then cooling it to room temperature;

[0108] (c) The designed film pattern is printed on the photoresist layer by ultraviolet exposure, the wavelength of the ultraviolet light of the ultraviolet exposure is 365nm, and the intensity of the ultraviolet light is 7.3mW / cm 2 , the UV exposure time is 15s, followed by baking at 100°C for 60s, and developing in AZ 826MIF developer for 50s to obtain a photoresist in the shape of a long parallelogram, wherein the bottom angle of one side of the long parallelogram is 20°, and the long side length of the long parallelogram is 50μm;

[0109] (d) depositing a nickel (Ni) thin film on the long parallelogram-shaped photoresist obtained in step (c) by electron beam evaporation, and the deposition rate of the electron beam evaporation is A nickel (Ni) material layer with a thickness of 80 nm is obtained; then it is immersed in N-methylpyrrolidone (NMP) at a temperature of 80° C., ultrasonically treated for 90 seconds, and then immersed for 2 days, and washed with isopropanol and water to obtain the spiral microrobot.

[0110] Example 4

[0111] The helical angle of the helical microrobot described in this embodiment is 53.5°, and its body length is 360 μm.

[0112] The method for preparing the spiral microrobot comprises the following steps:

[0113] (a) 5 mL of AZ nLof 2070 commercial photoresist was poured onto a clean silicon wafer and spin-coated at a rotation speed of 4000 rpm for 45 seconds to obtain a photoresist layer with a thickness of 8 μm;

[0114] (b) baking the photoresist layer obtained in step (a) at 110° C. for 90 seconds, and then cooling to room temperature;

[0115] (c) The designed film pattern is printed on the photoresist layer by ultraviolet exposure, the wavelength of the ultraviolet light of the ultraviolet exposure is 365nm, and the intensity of the ultraviolet light is 7.3mW / cm 2 , the UV exposure time is 20 seconds, followed by baking at 120° C. for 90 seconds, and developing in AZ 826MIF developer for 70 seconds to obtain a photoresist in the shape of a long parallelogram, wherein the bottom angle of one side of the long parallelogram is 53.5°, and the long side length of the long parallelogram is 700 μm;

[0116] (d) depositing a nickel film on the long parallelogram-shaped photoresist obtained in step (c) by electron beam evaporation, and the deposition rate of the electron beam evaporation is A nickel material layer with a thickness of 150 nm was obtained; then it was immersed in N-methylpyrrolidone (NMP) at a temperature of 80° C., ultrasonically treated for 60 seconds, and then immersed for 2 days, and washed with ethanol and water to obtain the spiral microrobot.

[0117] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a spiral microrobot, characterized in that: The method comprises the following steps: (1) forming a photoresist layer on a substrate and then baking it; The substrate comprises any one of a silicon wafer, silicon dioxide or silicon nitride; the photoresist of the photoresist layer is a negative photoresist, and the thickness of the photoresist layer is 2-8 μm; The method for forming a photoresist layer on a substrate comprises spin coating the photoresist on the substrate, wherein the spin coating speed is 2000-4000 rpm and the time is 45-30 s; The baking time is 60-90s, and the temperature is 110-90°C; (2) printing a long parallelogram on the photoresist layer by ultraviolet exposure, followed by baking and developing, wherein a bottom angle of one side of the long parallelogram is 15-75°; The intensity of the ultraviolet light of the ultraviolet exposure is 5-13mW / cm 2 , UV exposure time is 20-15s; The base angle of one side of the elongated parallelogram is 20-40°; The baking temperature is 80-120°C and the baking time is 90-60s; The development is carried out in a developer, and the development time is 50-70s; (3) vapor-depositing a metal material layer on the long parallelogram obtained in step (2), and then immersing the long parallelogram in a heated solvent to obtain the spiral microrobot; The evaporation is electron beam evaporation, and the deposition rate of the evaporation process is The helical angle of the spiral microrobot is 15-75°, and the body length of the spiral microrobot is 40-1000 μm.

2. The method for preparing a spiral microrobot according to claim 1, characterized in that: The spiral micro robot is obtained by curling a long parallelogram.

3. The method for preparing a spiral microrobot according to claim 2, characterized in that: The base angle of one side of the elongated parallelogram is 15-75°.

4. The method for preparing a spiral microrobot according to claim 3, characterized in that: The base angle of one side of the elongated parallelogram is 20-40°.

5. The method for preparing a spiral microrobot according to claim 1, characterized in that: The helical angle of the helical microrobot is 20-40°.

6. The method for preparing a spiral microrobot according to claim 1, characterized in that: The body length of the spiral microrobot is 50-400 μm.

7. The method for preparing a spiral microrobot according to claim 1, characterized in that: The spiral microrobot is a spiral sheet structure.

8. The method for preparing a spiral microrobot according to claim 7, characterized in that: The helical sheet structure has a sheet thickness of 20-300 nm.

9. The method for preparing a spiral microrobot according to claim 8, characterized in that: The helical sheet structure has a sheet thickness of 80-100 nm.

10. The method for preparing a spiral microrobot according to claim 1, characterized in that: The spiral micro robot is made of metal material.

11. The method for preparing a spiral microrobot according to claim 10, characterized in that: The spiral micro robot is made of ferromagnetic metal material.

12. The method for preparing a spiral microrobot according to claim 11, characterized in that: The material of the spiral microrobot is any one of nickel, titanium, cobalt, copper, gold, platinum, aluminum, iron or cobalt-nickel alloy, or a combination of at least two thereof.

13. The method for preparing a spiral microrobot according to claim 12, characterized in that: The material of the spiral microrobot is nickel.

14. The method for preparing a spiral microrobot according to claim 1, characterized in that: The solvent in step (3) is any one of N-methylpyrrolidone, dimethyl sulfoxide or acetone, or a combination of at least two of them.

15. The method for preparing a spiral microrobot according to claim 14, characterized in that: The solvent in step (3) is N-methylpyrrolidone.

16. The method for preparing a spiral microrobot according to claim 1, characterized in that: The temperature of the heated solvent in step (3) is 80-100°C.

17. The method for preparing a spiral microrobot according to claim 1, characterized in that: The soaking process in step (3) is accompanied by ultrasonic treatment.

18. The method for preparing a spiral microrobot according to claim 17, characterized in that: The ultrasonic treatment time is 30-120s.

19. The method for preparing a spiral microrobot according to claim 1, characterized in that: The soaking time in step (3) is 3-1 days.

20. The method for preparing a spiral microrobot according to claim 1, characterized in that: The soaking in step (3) also includes cleaning.

21. The method for preparing a spiral microrobot according to claim 20, characterized in that: The cleaning solution includes alcohol and water.

22. The method for preparing a spiral microrobot according to claim 21, characterized in that: The cleaning method includes first rinsing with alcohol and then rinsing with water.

23. The method for preparing a spiral microrobot according to claim 21, characterized in that: The alcohol includes isopropanol and / or ethanol.

24. The method for preparing a spiral microrobot according to claim 1, characterized in that: The method comprises the following steps: (a) pouring a photoresist onto a silicon wafer and spin coating the silicon wafer at a rotation speed of 2000-4000 rpm for 45-30 s to obtain a photoresist layer; (b) baking the photoresist layer obtained in step (a) at 90-110° C. for 90-60 seconds, and then cooling to room temperature; (c) Imprinting the designed film pattern on the photoresist layer by ultraviolet exposure, wherein the wavelength of the ultraviolet light of the ultraviolet exposure is 300-370nm, and the intensity of the ultraviolet light is 5-13mW / cm 2 , the UV exposure time is 20-15s, followed by baking at 80-120°C for 90-60s, and developing in a developer for 50-70s to obtain a photoresist in the shape of a long parallelogram; (d) depositing a metal material on the long parallelogram-shaped photoresist obtained in step (c) by electron beam evaporation, and the deposition rate of the electron beam evaporation is A metal material layer with a thickness of 20-300 nm is obtained; then the metal material layer is immersed in N-methylpyrrolidone at a temperature of 80-100° C. for 3-1 days to obtain the spiral micro robot.

25. Use of the spiral microrobot prepared by the method for preparing a spiral microrobot according to any one of claims 1 to 24, characterized in that: The spiral microrobot is used for targeted drug delivery.

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