CN106517081B - Magnetic encapsulation Micro-Robot and preparation method thereof - Google Patents

Abstract

A preparation method of a biocompatible magnetic microrobot, comprising: providing a silicon wafer, preparing an Omnicoat sacrificial layer on the silicon wafer; spin-coating an SU‑8 photoresist on the Omnicoat sacrificial layer to form an SU‑8 base layer; obtaining First prefabricated layer structure; Baking; Patterned exposure; Baking at 65°C for 2 minutes, then baking at 95°C for 2 minutes; Coating magnetic composite material on the SU‑8 base layer, baking; Patterning exposure; bake at 65°C for 2 minutes, then bake at 95°C for 2 minutes; develop, rinse with deionized water, and air dry; coat SU‑8 photoresist; bake; pattern exposure; at 65 ℃ for 2 minutes, and then baked at 95 ℃ for 2 minutes; develop, wash with deionized water, and air-dry; obtain biocompatible magnetic microrobots. The above-mentioned magnetically encapsulated micro-robot has good biocompatibility and chemical resistance.

Description

Magnetic encapsulated microrobot and its preparation method

technical field

The invention relates to micro-nano precision machining and characteristic micro-robot technology, in particular to a packaged magnetic micro-robot and a preparation method thereof.

Background technique

As the operating requirements of microscopically active samples are getting higher and higher, traditional micro-manipulation systems gradually show their limitations, such as the inevitable mechanical damage to living samples, limited movement space, and the inability to apply to strictly non-polluting fluid environments. Micro-robots based on magnetic force control are particularly suitable for working in small and closed environments due to their small size and free and unconstrained movement. At the same time, due to its own biocompatibility and chemical resistance, it minimizes the damage to living samples. It has great application prospects in the directional detection and targeted drug loading in the human body, the transport of particles in microfluidic channels, and the handling, classification, and assembly of microscopic objects in lab-on-a-chip.

In the past ten years, new ultra-precision processing technology and new functional materials have promoted the rapid development of micro-electromechanical system technology (MEMS). The emergence of micro-robots has a wide-ranging impact on industry and even on our daily lives. Magnetic drive also has the advantages of strong controllability, greater power, wide operating range and no harm, and is especially suitable for biomedical fields, especially in vivo interventional applications. Such as pipeline flaw detection in nuclear power plants, biomedical diagnosis and treatment. At present, the production of magnetic micro-robots mainly includes the following: fused deposition modeling, etching, laser cutting, integrated photomask micro-molding, micro-machining, two-photon polymerization, etc.

The micro-robots prepared by the above methods expose the magnetic materials to the external environment, which cannot guarantee that the magnetic robots have better biocompatibility and chemical resistance.

Contents of the invention

Based on this, it is necessary to provide a magnetically encapsulated microrobot with better biocompatibility and chemical resistance and a preparation method thereof.

A method for preparing a magnetically encapsulated microrobot, comprising:

Provide a silicon wafer on which an Omnicoat sacrificial layer is prepared;

Spin coating SU-8 photoresist on the Omnicoat sacrificial layer to form a SU-8 base layer; obtain the first prefabricated layer structure;

Bake the first prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes;

Using a mask aligner, subjecting the first prefabricated layer structure to patterned exposure for 20-35 seconds under the irradiation of an ultraviolet light source;

Bake the first prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes;

Coating a magnetic composite material on the SU-8 base layer to obtain a second prefabricated layer structure;

Bake the second prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes;

Using a mask aligner, subjecting the second prefabricated layer structure to patterned exposure for 25-35 seconds under the irradiation of an ultraviolet light source;

Bake the second prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes;

performing a developing operation on the second prefabricated layer structure;

Coating SU-8 photoresist on the outer surface of the second prefabricated layer structure to obtain a third prefabricated layer structure;

Bake the third prefabricated layer structure at 60-70°C for 1.5-3 minutes, and then bake at 90-100°C for 3-5 minutes;

Using a mask aligner, subjecting the third prefabricated layer structure to patterned exposure for 25-35 seconds under the irradiation of an ultraviolet light source;

Baking the third prefabricated layer structure at 60-70°C for 1.5-3 minutes, then baking at 90-100°C for 3-5 minutes; performing a developing operation on the third prefabricated layer structure to obtain a magnetically encapsulated microrobot .

In one of the embodiments, the magnetic composite material is composed of RuFeB magnetic powder and SU-8 photoresist.

In one embodiment, the magnetic composite material is composed of 60% RuFeB magnetic powder and 40% SU-8 photoresist.

In one embodiment, the average diameter of the RuFeB magnetic powder is 2 microns.

In one of the embodiments, the spin-coating of SU-8 photoresist on the Omnicoat sacrificial layer is as follows: first spin coating at 400-600rpm for 3-8s, and then at 1800-2000rpm Spin coating for 30s.

In one embodiment, the preparation method of the magnetic composite material is as follows: mixing 60% RuFeB magnetic powder and 40% SU-8 photoresist in a microcentrifuge tube.

In one of the embodiments, before the magnetic composite material is coated on the SU-8 base layer, the magnetic composite material is vortexed for 30 minutes under the condition of 3000r/min, so that the RuFeB magnetic powder is coated on the SU-8 base layer. 8 Uniform distribution in photoresist.

In one embodiment, the exposure energy for the patterned exposure of the second prefabricated layer structure is 130 mJ/cm ² .

In one of the embodiments, the developing operation of the second prefabricated layer structure is: soaking the second prefabricated layer structure in SU-8 photoresist developer to remove uncrosslinked SU-8 8 photoresist, then rinse with deionized water and air dry.

The developing operation of the third prefabricated layer structure is as follows: immerse the third prefabricated layer structure in SU-8 photoresist developer, remove the uncrosslinked SU-8 photoresist, and then use Rinse with deionized water and air dry.

A magnetically encapsulated microrobot, the magnetically encapsulated microrobot is the magnetically encapsulated microrobot obtained by the above preparation method.

In the above magnetic encapsulated micro-robot and its preparation method, since the magnetic particles are completely encapsulated in the inert SU-8 layer, the micro-robot has biocompatibility and chemical resistance. Using simple multi-layer photolithography, mass production can be achieved in one pass, improving time and cost efficiency.

Description of drawings

1 is a schematic diagram of a method for preparing a magnetically encapsulated microrobot according to an embodiment; and

FIG. 2 is an optical micrograph of a partial structure of a magnetically encapsulated microrobot in an embodiment.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the associated drawings. Preferred embodiments of the invention are shown in the accompanying drawings. The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process conversion made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technical fields , are all included in the scope of patent protection of the present invention in the same way.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terminology used herein in the description of the present invention is only for the purpose of describing specific embodiments, and is not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Please refer to Fig. 1, the preparation method of the magnetic encapsulation micro-robot of one embodiment, comprising:

S101, providing a silicon wafer, and preparing an Omnicoat sacrificial layer on the silicon wafer.

In one embodiment, as shown in a in FIG. 1 , an Omnicoat sacrificial layer is spin-coated on a silicon wafer at 2000 rpm/s to obtain a 10-15 nanometer thick Omnicoat sacrificial layer.

S102. Spin-coat SU-8 photoresist on the Omnicoat sacrificial layer to form a SU-8 base layer; obtain the first prefabricated layer structure.

In one embodiment, as shown in a in FIG. 1 , SU-8 photoresist is spin-coated on the Omnicoat sacrificial layer to obtain a 15 micron thick SU-8 photoresist layer.

In one embodiment, the method of spin-coating the SU-8 photoresist on the Omnicoat sacrificial layer is as follows: first spin-coating at a spin-coating speed of 400-600rpm for 3-8s, and then spin-coating at a spin-coating speed of 1800-2200rpm for 30s.

S103. Bake the first prefabricated layer structure at 60-70°C for 1.5-3 minutes, and then bake at 90-100°C for 3-5 minutes.

S104. Using a mask aligner, under the irradiation of a 4.33mW/cm ² ultraviolet light source, pattern-expose the first prefabricated layer structure for 20-35s.

In one embodiment, the exposure energy of the patterned exposure is 130 mJ/cm ² .

S105. Baking the first prefabricated layer structure at 60-70° C. for 1.5-3 minutes, and then baking at 90-100° C. for 3-5 minutes.

As shown in b in Fig. 1, cross-linked and uncross-linked SU-8 photoresist regions were formed after the patterned exposure.

S106, coating the magnetic composite material on the SU-8 base layer to obtain a second prefabricated layer structure.

In one embodiment, as shown in c in FIG. 1 , a 20-micron-thick magnetic composite material is coated on the SU-8 base layer to obtain a second prefabricated layer structure.

In one embodiment, the magnetic composite material is composed of RuFeB magnetic powder and SU-8 photoresist. In one embodiment, the magnetic composite material is composed of RuFeB magnetic powder with a mass fraction of 60% and SU-8 photoresist with a mass fraction of 40%.

In one embodiment, the average diameter of the RuFeB magnetic powder is 2 microns.

In one embodiment, the preparation method of the magnetic composite material is as follows: using a microcentrifuge tube to mix the RuFeB magnetic powder with a mass fraction of 60% and SU-8 photoresist with a mass fraction of 40%.

In one embodiment, in order to avoid the precipitation of magnetic particles and obtain a uniform dispersion composite material, the magnetic composite material was vortexed for 30 minutes under the condition of 3000 r/min before use. The above method can avoid the precipitation of the magnetic composite material, so that the magnetic composite material with uniform dispersion can be obtained.

S107. Baking the second prefabricated layer structure at 60-70° C. for 1.5-3 minutes, and then baking at 90-100° C. for 3-5 minutes.

S108. Using a mask aligner, under the irradiation of a 4.33mW/cm ² ultraviolet light source, pattern-expose the second prefabricated layer structure for 25-35s.

In one embodiment, the exposure energy of the patterned exposure is 130 mJ/cm ² .

S109. Baking the second prefabricated layer structure at 60-70° C. for 1.5-3 minutes, and then baking at 90-100° C. for 3-5 minutes.

In one embodiment, as shown in d in FIG. 1 , a cured magnetic composite material region and an uncured magnetic composite material region are formed after patterned exposure.

S110, performing a developing operation on the second prefabricated layer structure.

In one embodiment, the developing operation of the second prefabricated layer structure is as follows: soak the second prefabricated layer structure in SU-8 photoresist developer, remove the uncrosslinked SU-8 photoresist, and then use Rinse with deionized water and air dry.

In one embodiment, as shown in e in FIG. 1 , the uncrosslinked SU-8 photoresist is removed to develop the cured magnetic composite material.

S111. Coating SU-8 photoresist on the outer surface of the second prefabricated layer structure to obtain a third prefabricated layer structure.

In one embodiment, as shown by f in FIG. 1 , a 15 micron thick SU-8 photoresist is coated on the outer surface of the second prefabricated layer structure to obtain a third prefabricated layer structure.

S112. Bake the first prefabricated layer structure at 60-70° C. for 1.5-3 minutes, and then bake at 90-100° C. for 3-5 minutes.

In one embodiment, the third prefabricated layer structure is baked at 60-70° C. for 1.5-3 minutes, and then baked at 90-100° C. for 3-5 minutes.

S113. Using a mask aligner, under the irradiation of a 4.33mW/cm ² ultraviolet light source, pattern-expose the third prefabricated layer structure for 25-35s.

In one embodiment, the exposure energy of the patterned exposure is 130 mJ/cm ² .

S114. Baking the third prefabricated layer structure at 60-70° C. for 1.5-3 minutes, and then baking at 90-100° C. for 3-5 minutes.

S115 , performing a development operation on the third prefabricated layer structure to obtain a magnetically encapsulated microrobot.

In one embodiment, as shown in g in FIG. 1 , the developing operation for the third prefabricated layer structure is as follows: soak the third prefabricated layer structure in SU-8 photoresist developer to remove uncrosslinked SU -8 photoresist, then rinse with deionized water and air dry.

In the above magnetic encapsulated micro-robot and its preparation method, since the magnetic particles are completely encapsulated in the inert SU-8 layer, the micro-robot has biocompatibility and chemical resistance. Using simple multi-layer photolithography, mass production can be achieved in one pass, improving time and cost efficiency. Furthermore, by controlling the ratio of metal to polymer base, the properties of the material can be customized. These magnetic micro-robots can work in a variety of complex environments.

Please refer to FIG. 2 . In one embodiment, a magnetically encapsulated microrobot is a magnetically encapsulated microrobot obtained according to the preparation method described above.

As shown in Fig. 2, a–d represent high-resolution large magnetic core SU-8 geometric features, e represent Janus particles exhibiting controllable heterogeneity of magnetic particle density, and f represent high-resolution SU-8 with different internal and external shapes. 8 microstructures. g represents the contour data of the microrobot in c. Despite multiple coating and patterning steps, these composite structures exhibit similar clean, vertical sidewall geometries when compared to pure SU-8 patterning. The surface roughness of the top surface obtained by using white light scanning interferometry (Zygo Newview5000 profile scanner) is 1 μm.

The magnetically encapsulated micro-robot is prepared from three layers of photosensitive materials. The outer two surface layers are SU-8 photoresist, and the inner core layer is a magnetic composite material of RuFeB magnetic powder and SU-8 photoresist. Prepared by sequential coating and patterning of pure SU-8 and SU-8/NdFeB layers. This "sandwich" structure makes the magnetic particles completely encapsulated in the SU-8 layer. The magnetic microrobot has biocompatibility and chemical resistance.

The above examples only express several implementations of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. A preparation method for a magnetically encapsulated microrobot, characterized in that, comprising: Provide a silicon wafer on which an Omnicoat sacrificial layer is prepared; Spin coating SU-8 photoresist on the Omnicoat sacrificial layer to form a SU-8 base layer; obtain the first prefabricated layer structure; Bake the first prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes; Using a mask aligner, subjecting the first prefabricated layer structure to patterned exposure for 20-35 seconds under the irradiation of an ultraviolet light source; Bake the first prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes; Coating a magnetic composite material on the SU-8 base layer to obtain a second prefabricated layer structure; Bake the second prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes; Using a mask aligner, subjecting the second prefabricated layer structure to patterned exposure for 25-35 seconds under the irradiation of an ultraviolet light source; Bake the second prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes; performing a developing operation on the second prefabricated layer structure; Coating SU-8 photoresist on the outer surface of the second prefabricated layer structure to obtain a third prefabricated layer structure; Bake the third prefabricated layer structure at 60-70°C for 1.5-3 minutes, and then bake at 90-100°C for 3-5 minutes; Using a mask aligner, subjecting the third prefabricated layer structure to patterned exposure for 25-35 seconds under the irradiation of an ultraviolet light source; Bake the third prefabricated layer structure at 60-70°C for 1.5-3 minutes, then bake at 90-100°C for 3-5 minutes; A development operation is performed on the third prefabricated layer structure to obtain a magnetically packaged microrobot. 2. the preparation method of magnetic encapsulation micro-robot according to claim 1 is characterized in that, described magnetic composite material is made up of neodymium iron boron magnetic powder and SU-8 photoresist. 3. The method for preparing a magnetically encapsulated micro-robot according to claim 2, wherein the magnetic composite material is composed of 60% NdFeB magnetic powder and 40% SU-8 photoresist by mass fraction . 4. the preparation method of magnetic encapsulation micro-robot according to claim 2 is characterized in that, the average diameter of described neodymium iron boron magnetic powder is 2 microns. 5. the preparation method of magnetic encapsulation micro-robot according to claim 1, is characterized in that, described on described Omnicoat sacrificial layer, spin coating SU-8 photoresist is: be that 400-600rpm spins with spin coating speed first Coat for 3-8s, then spin-coat at 1800-2000rpm for 30s. 6. the preparation method of magnetic package micro-robot according to claim 1, is characterized in that, the preparation method of described magnetic composite material is: in microcentrifuge tube, mix mass fraction and be that 60% NdFeB magnetic powder and mass fraction are 40% SU-8 photoresist. 7. the preparation method of magnetic encapsulation micro-robot according to claim 6 is characterized in that, before coating magnetic composite material on described SU-8 base layer, described magnetic composite material is vortexed under the condition of 3000r/min Spin for 30 minutes to achieve uniform distribution of the NdFeB magnetic powder in the SU-8 photoresist. 8 . The method for manufacturing a magnetically encapsulated microrobot according to claim 1 , wherein the exposure energy for the patterned exposure of the second prefabricated layer structure is 130 mJ/cm ² . 9. The preparation method of magnetic encapsulation microrobot according to claim 1, is characterized in that: The developing operation of the second prefabricated layer structure is: soaking the second prefabricated layer structure in SU-8 photoresist developer, removing the uncrosslinked SU-8 photoresist, and then using Rinse with deionized water and air dry; The developing operation of the third prefabricated layer structure is as follows: immerse the third prefabricated layer structure in SU-8 photoresist developer, remove the uncrosslinked SU-8 photoresist, and then use Rinse with deionized water and air dry. 10. A magnetically encapsulated microrobot, characterized in that the magnetically encapsulated microrobot is obtained according to the preparation method according to any one of claims 1-9.