Preparation method and application of micro-robot

Abstract

The invention discloses a preparation method and application of a micro-robot, and belongs to the technical field of medicine. The preparation method comprises the following steps: preparing a hard template semi-finished product by adopting a 3D printing method; the hard template semi-finished product comprises a substrate, a male die on the front surface of the substrate and a supporting structure on the back surface of the substrate; removing the supporting structure to obtain a hard template; s2, pouring the PDMS precursor dispersion liquid on the front surface of the hard mold, curing and demolding to obtain a soft template; s3, a water-soluble sacrificial layer is formed on the surface of the substrate, and then the substrate is coated with nano-imprinting glue; s4, transferring the shape on the soft template to the surface of the nanoimprint glue by adopting contact type imprint, and demoulding after curing to obtain a green body; s5, sequentially forming a magnetic layer and a titanium metal film on the surface of the green body, and then separating the substrate; and the minimum detail precision of the micro-robot is greater than 0.2 mm. According to the preparation method provided by the invention, the production cost of the micro-robot can be effectively reduced, and the precision, the yield and the structure richness of the micro-robot are improved.

Description

Technical Field

[0001] The present invention relates to the field of medical technology, and in particular to a preparation method of a micro robot and application thereof. Background Art

[0002] Currently, the three most common cancer treatments on the market are chemotherapy, radiotherapy, and surgery. Surgical resection can completely remove the tumor, but the resulting trauma usually takes a long time to recover. Radiotherapy uses ionizing radiation to kill cancer cells, but it also kills normal cells, causing significant harm to the body. Chemotherapy treats cancer by transporting drugs through the bloodstream to the site of the disease. However, since drug diffusion is relatively random and poorly targeted, it can damage other cells in the body.

[0003] In order to minimize the damage of cancer treatment to normal human tissues, researchers have improved chemotherapy, specifically trying to transport drugs to the location of the lesion and then release the medicinal properties. This method requires a carrier that can transport drugs to a specific point, which we call a micro drug delivery robot.

[0004] Currently, the production cost of commonly used microrobots is quite high, making it difficult to produce them in large quantities with high precision. Although the commonly used ultraviolet lithography method can produce smaller robots, it can only achieve the production of simple flat robots.

[0005] Therefore, it is particularly important to improve the accuracy of microrobot preparation, enrich its structure, and reduce its cost. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for preparing a microrobot, which can effectively reduce the production cost of the microrobot and improve its accuracy and structural diversity.

[0007] The present invention also provides an application using the above preparation method.

[0008] According to an embodiment of the first aspect of the present invention, a method for preparing a microrobot is provided, wherein the minimum detail accuracy of the microrobot is greater than 0.2 mm; the method specifically comprises the following steps:

[0009] S1. Prepare a semi-finished hard template using a photo-stereolithography 3D printing method; the semi-finished hard template includes a substrate, a convex mold of the microrobot disposed on the front surface of the substrate, and a support structure disposed on the back surface of the substrate; the contact point between the support structure and the substrate has a size of 0.6 to 1.0 mm; remove the support structure to obtain the hard template;

[0010] S2 pouring the PDMS precursor dispersion on the front of the hard template, solidifying, removing the hard template to obtain a soft template;

[0011] S3. After forming a water-soluble sacrificial layer on the substrate surface, a nanoimprinting adhesive is applied;

[0012] S4. Using contact imprinting, the shape of the soft template is transferred to the surface of the nanoimprint adhesive, and the soft template is removed after curing to obtain a microrobot body;

[0013] S5. A magnetic layer and a titanium metal film are sequentially formed on the surface of the green body, and then the resulting component is shaken in water;

[0014] The thickness of the magnetic layer is greater than 20 nm.

[0015] The preparation method according to the embodiment of the present invention has at least the following beneficial effects:

[0016] This invention uses photocuring 3D printing to create hard templates, significantly increasing the structural diversity of microrobots compared to traditional coating and photocuring methods. Traditional photocuring, which typically relies on a photomask, can only produce columnar structures, the cross-sectional shape of which depends on the pore structure of the mask. However, 3D printing can produce not only columnar structures but also various irregular structures, such as spherical and bean-shaped structures.

[0017] Compared with the traditional coating-photocuring method, the 3D printing method adopted in the present invention does not need to consider the influence of coating thickness, distance between mask and coating, light direction, etc. on the shape and dimensional accuracy of the microrobot. The entire process relies on mechanical operation, which significantly improves the intra-batch and batch-to-batch dimensional accuracy and dimensional stability of the obtained microrobot.

[0018] The present invention adopts a combination of light-curing 3D printing and nanoimprinting to produce microrobots. Multiple products can be obtained in a single batch, which significantly reduces the preparation cost of a single product.

[0019] However, if the minimum detail accuracy is less than 0.2 mm, the fine structure of the punch surface will be unclear. The minimum detail accuracy refers to the minimum width of the punch.

[0020] In addition, if the size of the contact point (the size of the longest side of the contact point) is smaller than the range required by the present invention, the hard template will fall off directly inside the printer during the 3D printing process, and the surface convex mold cannot be completely printed, so it cannot be used to prepare the microrobot; if it is larger than the range required by the present invention, after removing the support structure, obvious traces will remain on the back of the hard template, affecting the flatness of the hard template, and thus affecting the dimensional accuracy and magnetism of the microrobot.

[0021] Within the thickness range of the magnetic layer provided by the present invention, the microrobot is heavy enough to sink to the bottom of the water and has sufficient magnetism, thereby facilitating magnetic control.

[0022] The invention incorporates a magnetic layer and titanium film on the surface of the microrobot, enhancing its point-of-use transport and biocompatibility. This approach is expected to find widespread application in the targeted delivery of drugs for cancer treatment.

[0023] According to some embodiments of the present invention, the minimum detail accuracy of the microrobot is 0.3-1.5 mm, for example, about 0.4 mm, 0.5 mm, or about 1.0 mm.

[0024] According to some embodiments of the present invention, step S1 further includes performing an inspection before 3D printing, wherein the inspection specifically includes whether the raw materials are sufficient, the 3D printing program, and the model settings are accurate.

[0025] According to some embodiments of the present invention, in step S1, the hard template is made from at least one of CastableWax 40v1 or Clear V4. This reduces the hard template's coefficient of expansion, mitigates the effects of temperature on its accuracy, and prevents temperature-induced bending and deformation of thin-walled structures, thereby improving the dimensional accuracy of the resulting microrobot. Furthermore, both of these materials support printing with a layer thickness of 0.025mm.

[0026] According to some embodiments of the present invention, in step S1 , the contact point between the support structure and the substrate is shaped like at least one of a circle and a rectangle.

[0027] According to some embodiments of the present invention, in step S1, the contact point between the support structure and the substrate is 0.6 to 0.9 mm. Specifically, for example, it can be approximately 0.7 mm or 0.8 mm. This prevents the support structure from being too large, which could leave residue after removal and affect the flatness of the hard template, ultimately affecting the dimensional accuracy and yield of the resulting microrobot. It also avoids the problem of the support structure being too small, which could hinder its detachment from the hard template after preparation (the support structure removal stage).

[0028] When the contact point is in a rectangular shape, the ratio of the length of the longest side to the shortest side of the contact point is 2 to 4:1; for example, it may be approximately 3:1.

[0029] According to some embodiments of the present invention, in step S1, the distribution density of the support structures is 2 to 4 per cm 2 ; For example, the specific is 3 / cm 2 .

[0030] According to some embodiments of the present invention, in step S1, the sum of the heights of the substrate and the support structure is 3 to 5 mm, for example, specifically about 4 mm. The thickness of the substrate is 1 to 2 mm, for example, specifically about 1.5 mm.

[0031] According to some embodiments of the present invention, in step S1, the longest side of the punch is attached to the front surface of the substrate. Furthermore, the largest surface of the punch is attached to the front surface of the substrate. As a result, the hard template has no hollow or concave structures along the Z-axis, avoiding the problem of nanoimprinting inability to produce hollow structures in step S4, thereby improving the dimensional accuracy and yield of the microrobot.

[0032] According to some embodiments of the present invention, step S1 further includes washing the hard template with alcohol. This can remove unreacted resin materials during the photocuring 3D printing process, preventing the resin materials from continuing to react and affecting the flatness of the hard template, thereby affecting the dimensional accuracy and yield of the microrobot.

[0033] The alcohol washing reagent includes an isopropyl alcohol aqueous solution. The concentration of the isopropyl alcohol aqueous solution is 70-90 wt %. For example, it can be about 80 wt %. Within this concentration range, the cleaning efficiency can be significantly improved, and the isopropyl alcohol volatilization caused by excessive concentration is avoided, thereby avoiding waste of the isopropyl alcohol.

[0034] The alcohol washing time is 3 to 15 minutes, for example, about 4 minutes, 5 minutes, 10 minutes or about 12 minutes.

[0035] The alcohol washing is carried out in combination with ultrasound and / or a brush.

[0036] According to some embodiments of the present invention, step S1 further includes a drying step after the alcohol washing.

[0037] The drying temperature is 55°C to 65°C, specifically about 60°C.

[0038] The drying time is 1 to 2 hours, for example, about 1.5 hours, so that the alcohol solvent used in the alcohol washing can be fully removed.

[0039] According to some embodiments of the present invention, step S2 further includes providing an isolation layer on the front of the hard template before pouring.

[0040] The isolation layer is made of a release agent. The release agent includes dimethyl silicone oil. The isolation layer is prepared from a dimethyl silicone oil solution in petroleum ether. The dimethyl silicone oil solution in petroleum ether has a concentration of 9-11% by weight, specifically approximately 10%. The isolation layer has a thickness of 0.8-1.5 μm, specifically approximately 1 μm.

[0041] The isolation layer is provided in a manner including spin coating.

[0042] According to some embodiments of the present invention, in step S2, the PDMS precursor dispersion includes PDMS (dimethylsilane) and a coagulant, wherein the coagulant includes at least one of vinyl silane, dimethyldiaminosilane, and polydimethylhydrogensiloxane.

[0043] According to some embodiments of the present invention, the mass ratio of PDMS to coagulant in the PDMS precursor solution is 9 to 11:1. For example, it can be approximately 10:1. As a result, the PDMS precursor solution solidifies upon heating. The resulting soft template is chemically stable and suitable for forming specific shapes through inverted molding.

[0044] According to some embodiments of the present invention, the PDMS precursor solution is further subjected to a vacuum degassing treatment before use, wherein the vacuum degassing treatment lasts for ≥30 min.

[0045] According to some embodiments of the present invention, in step S2, the curing temperature is 68°C to 72°C, specifically about 70°C.

[0046] According to some embodiments of the present invention, in step S2, the curing time is 10 hours to 11 hours, specifically about 10 hours.

[0047] According to some embodiments of the present invention, in step S3, the substrate is made of silicon.

[0048] According to some embodiments of the present invention, step S3 further includes pre-treating the substrate before forming the water-soluble sacrificial layer. The purpose of the pre-treatment is to improve the hydrophilicity of the substrate surface. The pre-treatment steps are:

[0049] The substrate is cleaned using O2 plasma.

[0050] The radio frequency power of the O2 plasma is 400W.

[0051] The cleaning time of the O2 plasma is 230 to 250 seconds, and can be specifically about 240 seconds.

[0052] According to some embodiments of the present invention, in step S3, the water-soluble sacrificial layer is made of dextran. Thus, in step S5, the microrobot and the substrate can be separated by shaking in water.

[0053] According to some embodiments of the present invention, in step S3, the water-soluble sacrificial layer is prepared by spin-coating a dextran aqueous solution onto the substrate surface and then drying.

[0054] The concentration of the dextran aqueous solution is 9.8-10.2 wt %, and specifically can be about 10 wt %.

[0055] The dextran aqueous solution needs to be heated before use, and the heating temperature is 28-32° C.; for example, it can be about 30° C.

[0056] The rotation speed of the spin coating is 2500-3500 r / s, and can be specifically about 3000 r / s.

[0057] The drying temperature is 95-105°C, and specifically can be about 100°C.

[0058] The drying time is 2 minutes 40 seconds to 3 minutes 10 seconds, and can be specifically about 3 minutes.

[0059] According to some embodiments of the present invention, in step S3, the nanoimprint adhesive is SU8 2000.5 photoresist. If a different type of photoresist is used, the rotation speed should be selected according to the rotation speed / thickness curve in the model specification. As long as contact imprinting and light curing can be achieved, the present invention is not strictly limited to this.

[0060] According to some embodiments of the present invention, in step S3, the nanoimprint adhesive is applied by spin coating at a speed of 2800 rpm to 3300 rpm, and specifically about 3000 rpm.

[0061] According to some embodiments of the present invention, step S4 further includes removing a residual layer; the residual layer is a connecting structure between two adjacent blanks.

[0062] According to some embodiments of the present invention, the method for removing the residual layer includes etching.

[0063] The etching method includes oxygen plasma etching. The plasma conditions used in the etching are as follows:

[0064] The power setting is 118w-122w, specifically about 120w;

[0065] The etching time is 55s to 65s, and specifically can be about 60s.

[0066] Since the height of the green body after contact imprinting is much greater than the height of the residual layer, the process of etching away the residual layer has a negligible effect on the green body.

[0067] According to some embodiments of the present invention, in step S5 , the material of the magnetic layer includes nickel.

[0068] According to some embodiments of the present invention, in step S5, the thickness of the magnetic layer is 25-80 nm, for example, about 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 60 nm, or about 70 nm.

[0069] According to some embodiments of the present invention, in step S5, the thickness of the titanium metal film is 9-11 nm, for example, about 10 nm.

[0070] According to some embodiments of the present invention, in step S5, the magnetic layer and the titanium metal film are formed using a dual-chamber magnetron sputtering apparatus. Dual-chamber magnetron sputtering allows for simultaneous coating of both materials. The two coatings should be completed as quickly and consecutively as possible. Prolonged intervals between coatings can lead to the formation of an oxide film, which can reduce the robot's yield.

[0071] In dual-chamber magnetron sputtering, the specific parameters include at least one of the following parameters:

[0072] (1) The DC power supply power of magnetron sputtering is 50W;

[0073] (2) The carrier gas flow rate in magnetron sputtering is 50 sccm;

[0074] Under the control of the above parameters, the coating rate of the magnetic layer is 3.52 nm / min.

[0075] And combined with the above coating rate and the thickness of the film to be coated, the required coating time is calculated.

[0076] However, the adhesion of the coating material using electron beam evaporation technology is weak, and the multi-layered material is more likely to fall off, which greatly reduces the yield rate.

[0077] According to an embodiment of the second aspect of the present invention, there is provided a drug-carrying robot, which includes a microrobot manufactured by the manufacturing method described in the embodiment of the first aspect of the present invention.

[0078] Since the drug-carrying robot adopts all the technical solutions of the preparation method of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment.

[0079] According to some embodiments of the present invention, the drug-carrying robot includes the microrobot and the drug carried by the microrobot. In actual use, the microrobot can be magnetically controlled to reach the lesion and release the drug in a concentrated manner, thereby reducing damage to normal cells and tissues in the human body during radiotherapy.

[0080] Unless otherwise specified, the term “about” in the present invention actually means that the error is allowed to be within the range of ±2%, for example, about 100 actually means 100±2%×100.

[0081] Unless otherwise specified, “between” in the present invention includes the number itself, for example, “between 2 and 3” includes the endpoint values ​​2 and 3.

[0082] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0084] Figure 1 This is a model diagram used for 3D printing in Example 1 of the present invention;

[0085] Figure 2 This is a structural design diagram of the microrobot in Example 1 of the present invention.

[0086] Figure 3 1 is a structural design diagram of the micro robot in comparative example 1 of the present invention.

[0087] Figure 4 This is a front view of the hard template actually obtained in Comparative Example 1 of the present invention.

[0088] Figure 5 This is an apparent view of the reverse side (the surface where the support structure is located) of the semi-finished hard template obtained in Example 1 of the present invention.

[0089] Figure 6 This is a reverse morphology image of the hard template obtained in Example 1 of the present invention.

[0090] Figure 7 This is a front view of the hard template obtained in Example 1 of the present invention.

[0091] Figure 8 It is microscopic observation Figure 7 The morphology of the resulting punch.

[0092] Figure 9 This is a partial flow chart of step S2 of Example 1 of the present invention.

[0093] Figure 10 It is a flow chart of steps S3 to S4 of Example 1 of the present invention.

[0094] Figure 11 It is a flow chart of step S5 of embodiment 1 of the present invention.

[0095] Figure 12 This is an apparent view of the reverse side of the semi-finished hard template obtained in Comparative Example 2 of the present invention.

[0096] Figure 13 This is a morphology diagram of the reverse side of the hard template obtained in Comparative Example 2 of the present invention.

[0097] Figure 14 This is the surface morphology of the hard template obtained in Example 2 of the present invention.

[0098] Figure 15 This is a diagram showing the dispersion of the microrobot obtained in Comparative Example 4 of the present invention in water. DETAILED DESCRIPTION

[0099] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0100] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0101] Example 1

[0102] In this example, a microrobot was prepared. The specific steps are as follows:

[0103] S1. Prepare a semi-finished hard template using a photo-curing 3D printing method; the semi-finished hard template includes a substrate, a convex mold of a micro-robot disposed on the front side of the substrate, and a support structure disposed on the back side of the substrate; remove the support structure to obtain a hard template; and wash the obtained hard template with alcohol.

[0104] The structure of the semi-finished hard formwork is designed by solidwork modeling. The designed model is as follows Figure 1The hard template is made of clear V4.

[0105] The thickness of the substrate is 1.5 mm;

[0106] The structure of the punch is as follows Figure 2 As shown in the figure, the longest side of the punch is in close contact with the substrate, and the resulting hard template has almost no hollow structure in the Z-axis direction. In the punch with this structure, the minimum detail accuracy is the diameter of the arc at both ends of the pea shape, which is 0.3mm in this example.

[0107] The density of the support structure is set to 3 / cm 2 The contact point between the support structure and the substrate is rectangular, with the longest side measuring 0.6 mm; the shortest side is approximately 0.2 mm long; and the height of the support structure is 2.5 mm.

[0108] The alcohol washing method is to soak in an isopropyl alcohol aqueous solution (70 wt %) for 10 min; remove the residual resin with ultrasound and a soft brush, and then bake at 60° C. for 1.5 h (using a constant temperature heating table).

[0109] The structure of the hard template obtained in this example is as follows Figure 5 After removing the support structure, there is almost no trace of support points on the surface (back side); the specific morphology is as follows Figure 6 As shown (SEM test). The front appearance of the hard template is as follows Figure 7 As shown, the convex mold obtained by microscope observation is as follows Figure 8 As shown. Figure 8 and Figure 2 The design shapes are almost the same and there is no residual glue on the surface.

[0110] S2. Spin-coat a layer of release agent (spin-coating solution is a 10% mass concentration of dimethyl silicone oil in petroleum ether solution) on the front of the hard template to form a 1 μm thick isolation layer; then pour the PDMS precursor dispersion on the surface of the isolation layer, solidify it, remove the hard template, and obtain a soft template; wherein,

[0111] The PDMS precursor dispersion was prepared by mixing PDMS (dimethylsilane) and a coagulant (vinylsilane) in a mass ratio of 9:1 and then degassing the mixture under vacuum for 30 minutes.

[0112] After pouring, the PDMS precursor dispersion should at least cover the convex mold.

[0113] The curing temperature is 70° C. and the curing time is 10 h; this is specifically achieved in an oven.

[0114] The flow chart of this step is as follows Figure 9 shown.

[0115] S3. After forming a water-soluble sacrificial layer on the surface of the substrate, a nanoimprinting adhesive is applied; wherein,

[0116] The substrate is a silicon wafer, which needs to be cleaned with oxygen plasma with a radio frequency power of 400W for 240s before use to form a hydrophilic layer on its surface.

[0117] The water-soluble sacrificial layer was prepared by heating a 10 wt % aqueous solution of dextran to 30°C in a water bath and then spin coating it on the substrate surface at a speed of 3000 r / s (using a spin coater). After spin coating, the resulting component was dried in a drying machine (constant temperature heating table) at 100°C for 3 minutes.

[0118] The nanoimprint glue used in this example is SU8 2000.5 photoresist, and the spin coating speed is 3000 r / s (using a spin coater).

[0119] S4. Using contact imprinting, the soft template and the substrate coated with nanoimprint glue are placed in the limiting groove of the imprinting device. Pressure is applied to transfer the shape of the former to the surface of the nanoimprint glue. Ultraviolet light is activated for exposure and curing. The nanoimprint glue is shaped, and the soft template is removed (the nanoimprint machine will adsorb the soft template and separate it from the embryo after the imprinting operation is completed). The microrobot embryo is obtained, and the connection position (residual layer) between two adjacent embryos is etched; the etching method used is to use O2 plasma cleaning, the power is set to 120w, and the etching time is 60s.

[0120] The flow chart of steps S3 to S4 is as follows: Figure 10 shown.

[0121] S5. Form a magnetic layer and a titanium metal film on the surface of the blank in sequence, and then shake the resulting component in water.

[0122] The magnetic layer is set up in a dual-chamber magnetron sputtering instrument using a nickel target, with the parameters set as a DC power supply power of 50 W and a carrier gas flow rate of 50 sccm for magnetron sputtering; under the control of the above parameters, the coating rate of the magnetic layer is 3.52 nm / min. Based on the required coating thickness of 50 nm, the coating time should be set to 14 min 10 s.

[0123] The thickness of the titanium metal film is 10 nm; the coating process parameters are the same as the magnetic layer parameters.

[0124] The flow chart of this step is as follows Figure 11 shown.

[0125] Example 2

[0126] This example provides a method for preparing a microrobot, which differs from Example 1 in that:

[0127] Step S1 does not include alcohol washing.

[0128] The surface morphology of the hard template obtained in step S1 of this example is as follows Figure 14 As shown in the figure, there are certain residues on the surface of the hard template; these residues have a certain probability of affecting the dimensional accuracy of the final microrobot.

[0129] Example 3

[0130] This example provides a method for preparing a microrobot, which differs from Example 1 in that:

[0131] In step S5 , the thickness of the magnetic layer is 70 nm.

[0132] Comparative Example 1

[0133] This example provides a method for preparing a micro robot. The specific difference from Example 1 is that the size of the micro robot is set differently. The specific size setting is as follows: Figure 3 As shown, the minimum detail accuracy is 0.1mm.

[0134] The results show that there is no clear structure on the convex side of the hard template because the minimum detail accuracy is less than the minimum value required by the present invention. The hard template has the appearance of the convex side as shown in FIG. Figure 4 shown. Figure 4 and subsequent Figure 6 、 Figure 13 、 Figure 14 The acquisition method is optical microscopy.

[0135] Comparative Example 2

[0136] This example provides a method for preparing a microrobot, which differs from Example 1 in that:

[0137] In step S1 , the contact point between the support structure and the substrate is set to be a rectangle with the longest side being 1.2 mm and the shortest side being 0.4 mm.

[0138] The appearance of the semi-finished hard template is as follows: Figure 12 shown.

[0139] After removing the support structure, the SEM image of the back is as follows Figure 13 That is, there are obvious long strip support marks on the back, which may affect the flatness of the back surface of the obtained hard template and further affect the dimensional accuracy of the obtained microrobot.

[0140] Comparative Example 3

[0141] This example provides a method for preparing a microrobot, which differs from Example 1 in that:

[0142] In step S1 , the contact point between the support structure and the substrate is set to be a rectangle with the longest side being 0.5 mm and the shortest side being about 0.17 mm.

[0143] The resulting support structure cannot support the hard template. During the printing process, the hard template falls off directly inside the printer. After the hard template is removed, it cannot be used as a hard template for casting and subsequent operations because it has fallen off before the printing is completed and lacks surface features.

[0144] Comparative Example 4

[0145] This example provides a method for preparing a microrobot, which differs from Example 1 in that:

[0146] In step S5 , the thickness of the magnetic layer is 20 nm.

[0147] Test Case

[0148] This example tested the precision and magnetic control capabilities of the microrobots produced in the examples and comparative examples. The testing method consisted of microrobots randomly observed under a microscope to determine the proportion of robots in the batch that had no abnormal shapes, as well as the proportion of robots in the batch that could function normally using coil control. The test results are shown in Table 1.

[0149] Table 1 Dimensional accuracy and magnetic control capability of the microrobots obtained in the examples and comparative examples

[0150] Accuracy Magnetic control capability Example 1 91.2％ 89.6％ Example 2 78.4％ 76.6％ Example 3 91.7％ 91.4％ Comparative Example 1 none none Comparative Example 2 35.4％ 33.9％ Comparative Example 3 none none Comparative Example 4 90.1％ 13.8％

[0151] 'None' in the table means no corresponding finished product was obtained

[0152] This example also tests the magnetic controllability of the microrobots obtained in the examples and comparative examples. The results show that the microrobots obtained in the other examples and comparative examples did not lose step at 12 Hz and had high controllability. The microrobot obtained in comparative example 4 lost step slightly at 3 Hz and could not be flipped. The thinning of the magnetic layer also caused the microrobot to become lighter, which in turn caused some of the microrobots to float in water (simulating the human body environment) and could not be fully controlled. The magnetic control results of comparative example 4 are shown in Figure 2. Figure 15 shown.

[0153] While the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A method for preparing a microrobot, characterized in that: The minimum detail accuracy of the microrobot is >0.2mm; The preparation method comprises the following steps: S1. Prepare a semi-finished hard template using a photo-curing 3D printing method; the semi-finished hard template includes a substrate, a convex mold of the microrobot provided on the front surface of the substrate, and a support structure provided on the back surface of the substrate; the contact point size between the support structure and the substrate is 0.6 to 1.0 mm; Removing the support structure to obtain a hard template; S2 pouring a PDMS precursor dispersion on the front of the hard template, curing, and removing the hard template to obtain a soft template; S3. After forming a water-soluble sacrificial layer on the substrate surface, a nanoimprinting adhesive is applied; S4. Using contact imprinting, the shape of the soft template is transferred to the surface of the nanoimprint adhesive, and the soft template is removed after curing to obtain a microrobot body; S5. A magnetic layer and a titanium metal film are sequentially formed on the surface of the green body, and then the resulting component is shaken in water; The thickness of the magnetic layer is greater than 20 nm.

2. The preparation method according to claim 1, characterized in that In step S1 , the contact point size between the support structure and the substrate is 0.6-0.7 mm.

3. The preparation method according to claim 1, characterized in that Step S1 further includes washing the hard template with alcohol.

4. The preparation method according to claim 1, characterized in that In step S5, the thickness of the magnetic layer is 25-80 nm.

5. The preparation method according to any one of claims 1 to 4, characterized in that In step S2, the PDMS precursor dispersion includes PDMS and a coagulant.

6. The preparation method according to claim 5, characterized in that In the PDMS precursor solution, the mass ratio of the PDMS to the coagulant is 9 to 11:

1.

7. The preparation method according to any one of claims 1 to 4, characterized in that In step S3, the material of the water-soluble sacrificial layer is dextran.

8. The preparation method according to any one of claims 1 to 4, characterized in that Step S4 also includes removing a residual layer; the residual layer is a connecting structure between two adjacent blanks.

9. The preparation method according to any one of claims 1 to 4, characterized in that In step S5, the material of the magnetic layer includes nickel; Preferably, in step S5, the thickness of the titanium metal film is 9-11 nm.

10. A medicine-carrying robot, characterized in that: The drug-carrying robot comprises a microrobot prepared by the preparation method according to any one of claims 1 to 9.

Images