A method for preparing flexible microchannels

Abstract

This invention provides a method for fabricating flexible microchannels using photoresist-assisted 3D printing. The method includes: drawing a channel model using a computer and printing the microchannel template using a 3D printer; cleaning the surface of the printed microchannel template; spin-coating photoresist onto the cleaned surface of the microchannel template; curing the photoresist using an ultraviolet light exposure machine to obtain a smooth microchannel mold; pouring a mixture of liquid polydimethylsiloxane (PDMS) and a curing agent onto the smooth microchannel mold; curing the PDMS in an oven; and then peeling the solid PDMS off the mold to obtain the flexible microchannel. This method offers advantages such as simple process, low cost, and high channel smoothness, solving the problem of rough channel surfaces in traditional 3D printing microchannel fabrication techniques. It is suitable for the rapid and large-scale manufacturing of microfluidic chips.

Description

Technical Field

[0001] This invention relates to the field of micro-nano fabrication technology, and more particularly to a method for preparing flexible microchannels. Background Technology

[0002] Microfluidics is a technology that controls fluids at the micrometer or nanometer level. Utilizing microchannels and microvalves within microfluidic chips, it allows for precise control of processes such as flow, mixing, separation, and detection of microfluidics, offering advantages such as ease of operation, high efficiency, speed, and low cost. Microfluidics is widely used in fields such as chemical analysis, biological detection, medical diagnostics, and environmental monitoring. Materials used in the manufacture of microfluidic chips include glass, silicon, and polymers, with primary processing techniques including photolithography, thermoforming, and laser cutting.

[0003] Photolithography uses light sources such as ultraviolet light to create microchannel patterns on photosensitive materials, and then transfers the patterns to a substrate using chemical or physical methods. This method can produce high-precision, high-density microchannel structures, but it requires expensive equipment and complex processes, and it is difficult to fabricate three-dimensional microchannels.

[0004] Thermoplastic molding utilizes the deformation of thermoplastic polymers under heat and pressure to imprint a pre-made microchannel mold onto the polymer, forming a microchannel structure. This method can produce low-cost, large-area microfluidic chips, but it is difficult to control the depth and width of the microchannels, and it is susceptible to thermal deformation and stress relaxation.

[0005] Laser cutting uses a laser beam to cut the outline of microchannels into materials such as polymers or glass, and then the two cut layers of material are bonded together to form a microchannel structure. This method can create microchannels of any shape without the need for molds and photolithography equipment, but the cutting speed is relatively slow and it is prone to thermal damage and residual stress.

[0006] 3D-printed microchannels are a novel manufacturing technology combining microfluidics and 3D printing. 3D printing allows for precise control over the shape, size, and complexity of microchannels, enabling the rapid fabrication of microfluidic chips. Compared to traditional microfabrication techniques, 3D-printed microchannels offer advantages such as faster manufacturing speed, lower cost, more flexible design, and greater customization. Based on their process flow, they can be categorized into three types:

[0007] Direct molding method: This method uses stereolithography (SLA) 3D printing technology to directly print microchannels within the structure. However, this method requires extremely high precision from the 3D printer, and the roughness of the channel's inner wall can affect fluid flow and observation. Furthermore, the chips are not reusable, requiring repeated printing and consuming more consumables.

[0008] The mold sacrifice method utilizes fused deposition modeling (FDM) 3D printing technology to print channels using soluble materials, then encapsulates them with silicone and cleans the channels with solvents or high temperatures after curing. However, this method suffers from low printing accuracy, difficulty in completely cleaning the sacrificial material, and the inability to reuse the chip.

[0009] Casting method: Microchannel anolyte films are printed using SLA or FAM printing technology, and PDMS microchannels are obtained by casting with polydimethylsiloxane (PDMS). However, the surface of 3D printed structures is often not smooth enough, which can affect the sealing and observation of microchannels. In addition, in SLA technology, the photosensitive resin is not resistant to high temperatures after curing and is prone to thermal deformation, affecting the microchannel forming effect. Therefore, PDMS needs to be cured at low temperatures, requiring a longer time. Summary of the Invention

[0010] To address the aforementioned technical issues, a method for fabricating flexible microchannels using photoresist-assisted 3D printing is provided. This method involves printing a microchannel template using a 3D printer, then spin-coating photoresist onto the template surface for surface modification. After the template is cured, a microchannel mold is obtained, and a microfluidic chip is obtained by casting and demolding PDMS.

[0011] The technical means employed in this invention are as follows:

[0012] A method for fabricating flexible microchannels, comprising photoresist-assisted 3D printing, including:

[0013] The channel model was drawn using a computer, and the microchannel template was printed using a 3D printer;

[0014] Clean the surface of the printed microchannel template;

[0015] Photoresist is spin-coated onto the upper surface of the cleaned microchannel template;

[0016] A smooth microchannel mold was obtained by curing the photoresist using an ultraviolet light exposure machine.

[0017] A mixture of liquid PDMS and curing agent is poured into a smooth microchannel mold;

[0018] After curing PDMS in an oven, the solid PDMS is peeled off from the mold to obtain flexible microchannels.

[0019] Furthermore, the step of using a computer to draw the channel model and using a 3D printer to print the microchannel template includes:

[0020] Use computer-aided design software to design and draw microchannel template drawings;

[0021] Import the drawn microchannel template drawing into the slicing software in .stl file format for slicing processing;

[0022] Set the exposure parameters;

[0023] Use an SLA printer to print the microchannel template.

[0024] Furthermore, the cleaning of the surface of the printed microchannel template includes:

[0025] Soak the 3D-printed microchannel template in 95% alcohol for 10–20 minutes;

[0026] The microchannel template was ultrasonically vibrated for 3-5 minutes to remove any uncured material remaining on the surface of the microchannel template.

[0027] Further, the spin-coating of photoresist onto the upper surface of the cleaned microchannel template includes:

[0028] The microchannel template, after surface cleaning, is adsorbed onto a spin coater under vacuum negative pressure. The spin coater is then used to spin-coat photoresist onto the surface of the microchannel template, so that the photoresist evenly covers the surface of the microchannel template.

[0029] Furthermore, the step of curing the photoresist with an ultraviolet light exposure machine to obtain a smooth microchannel mold includes:

[0030] After spin coating the photoresist, the microchannel template is placed in an ultraviolet exposure machine to cure the spin-coated photoresist.

[0031] After exposure, the microchannel template is removed from the UV exposure machine to obtain a smooth microchannel mold.

[0032] Furthermore, the process of casting the liquid PDMS and curing agent mixture onto a smooth microchannel mold includes:

[0033] A smooth microchannel mold is fixed in a petri dish, and a mixture of liquid PDMS and curing agent is added to the petri dish;

[0034] The liquid PDMS and curing agent mixture added to the petri dish was kept at a height of 3 mm from the upper surface of the channel mold, and left to stand for 20 min.

[0035] Furthermore, after curing PDMS in an oven, the solid PDMS is peeled off from the mold to obtain flexible microchannels, including:

[0036] The culture dish, along with the microchannel mold and the mixture of liquid PDMS and curing agent, was placed in an oven to transform the liquid PDMS and curing agent mixture into solid PDMS.

[0037] Remove the microchannel fabrication device from the oven and allow it to cool to room temperature;

[0038] The solid PDMS was peeled off from the microchannel template using an L-shaped peeling method;

[0039] Holes are punched in the solid PDMS reservoir to serve as the inlet and outlet for the liquid;

[0040] Solid PDMS and glass slides were placed together in a plasma cleaner for oxygen plasma surface treatment.

[0041] Solid PDMS and glass slides were removed from the plasma cleaning agent and bonded together to obtain a microchannel with a smooth inner surface and excellent sealing performance.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] 1. The flexible microchannel fabrication method provided by this invention can produce microfluidic chips with complex and controllable structures, and the processing is simple, fast, low-cost, and the structure is precise and controllable.

[0044] 2. The flexible microchannel preparation method provided by this invention has a simple preparation process, does not require complex instruments and strict laboratory conditions, and can quickly, efficiently and in batches produce microchannels suitable for various application scenarios.

[0045] 3. The flexible microchannel fabrication method provided by this invention can solve the problem that the rough surface of the mold affects observation and is prone to leakage in the existing 3D printed microchannel mold technology.

[0046] 4. The flexible microchannel preparation method provided by this invention can be combined with microfluidic technology to provide a rapid and efficient preparation method for complex microchannel structures. It does not require complex instruments and harsh experimental conditions. The method provided by this invention can produce PDMS microchannels in batches at low cost, effectively overcoming the various shortcomings of the prior art and having high industrial application value.

[0047] Based on the above reasons, this invention can be widely applied in fields such as micro-nano fabrication. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the 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 based on these drawings without creative effort.

[0049] Figure 1This is a flowchart illustrating the photoresist-assisted 3D printing process for fabricating flexible microchannels according to the present invention.

[0050] Figure 2 The microchannel template drawing provided for the embodiments of the present invention.

[0051] Figure 3 This is a schematic diagram of spin-coating photoresist onto a microchannel template provided in an embodiment of the present invention.

[0052] Figure 4 This is a schematic diagram illustrating the casting of a mixture of polydimethylsiloxane (PDMS) and a curing agent (in a mass ratio of 10:1) onto a microchannel mold, as provided in an embodiment of the present invention.

[0053] Figure 5 This is a schematic diagram of the microchannels prepared according to an embodiment of the present invention.

[0054] In the figure: 21, model substrate; 22, square microchannel; 23, liquid reservoir; 31, microchannel template; 32, spin coater; 41, microchannel mold; 42, petri dish; 43, mixture of liquid PDMS and curing agent; 51, solid PDMS; 52, glass slide; 53, microchannel. Detailed Implementation

[0055] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0057] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0058] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0059] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0060] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0061] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0062] like Figure 1As shown, this invention provides a method for fabricating flexible microchannels, which uses photoresist-assisted 3D printing to fabricate flexible microchannels, including:

[0063] S1. The channel model is drawn using a computer, and the microchannel template is printed using a 3D printer;

[0064] S2. Clean the surface of the printed microchannel template;

[0065] S3. Spin-coat photoresist onto the upper surface of the cleaned microchannel template;

[0066] S4. Use an ultraviolet light exposure machine to cure the photoresist to obtain a smooth microchannel mold;

[0067] S5. Pour liquid polydimethylsiloxane (PDMS) and curing agent mixture into a smooth microchannel mold;

[0068] S6. After curing PDMS in an oven, the solid PDMS is peeled off from the mold to obtain flexible microchannels.

[0069] In a specific implementation, as a preferred embodiment of the present invention, step S1 involves using a computer to draw a channel model and using a 3D printer to print the microchannel template, including:

[0070] S11. Use computer-aided design software to design and draw microchannel template drawings; such as... Figure 2 As shown, in the microchannel template of this embodiment, the substrate 21 is 30mm long, 20mm wide, and 1mm thick; the microchannel 22 is a square straight channel with a width of 100um and a height of 50um, and a total length of 20mm; the liquid storage pools 23 on both sides of the microchannel are circular with a diameter of 2mm and a height of 50um.

[0071] S12. Import the drawn microchannel template drawing into AnycubicPhotonWorkshop V3.10 slicing software in .stl file format for slicing processing;

[0072] S13. Set the exposure parameters; preferably, in this embodiment, the printing layer height is set to 50um and the single-layer exposure time is 3.5s.

[0073] S14. Print the microchannel template using an SLA printer. Preferably, in this embodiment, the printing material is photosensitive resin.

[0074] In a specific implementation, as a preferred embodiment of the present invention, step S2, cleaning the surface of the microchannel template after printing, includes:

[0075] S21. Soak the 3D printed microchannel template in 95% alcohol for 10-20 minutes;

[0076] S22. Use ultrasound to vibrate the soaked microchannel template for 3-5 minutes to remove the uncured material remaining on the surface of the microchannel template.

[0077] In a specific implementation, as a preferred embodiment of the present invention, step S3, spin-coating photoresist onto the upper surface of the cleaned microchannel template, includes:

[0078] The microchannel template 31, after surface cleaning, is adsorbed onto a spin coater 32 under vacuum negative pressure. Photoresist is then spin-coated onto the surface of the microchannel template 31 using the spin coater 32. In this embodiment, preferably, 2 ml of photoresist is dropped onto the template surface. The photoresist is preferably SU82002 photoresist manufactured by Microchem, ensuring uniform coverage of the microchannel template 31. Figure 3 As shown. Preferably, the spin coating process of spin coater 32 includes:

[0079] S31. Spin coating: Spin coating speed 500 rpm, spin coating acceleration 100 rpm / s, spin coating time 15s;

[0080] S32, Spin coating: Spin coating speed 3000rpm, spin coating acceleration 300rpm / s, spin coating time 30s.

[0081] In a preferred embodiment of the present invention, step S4, which involves curing the photoresist with an ultraviolet light exposure machine to obtain a smooth microchannel mold, includes:

[0082] S41. Place the microchannel template after spin-coating the photoresist into an ultraviolet exposure machine to cure the spin-coated photoresist; the preferred exposure dose is 100mJ / cm2.

[0083] S42. Remove the microchannel template from the UV exposure machine after exposure to obtain a smooth microchannel mold 41.

[0084] In a preferred embodiment of the present invention, step S5, which involves casting a mixture of liquid PDMS and a curing agent onto a smooth microchannel mold, includes:

[0085] S51. Fix the smooth microchannel mold 41 in the culture dish 42, and add a mixture of liquid PDMS and curing agent to the culture dish; in this embodiment, preferably, the culture dish 42 has a diameter of 5cm and a height of 1cm. Figure 4 As shown. The mixture of liquid PDMS and curing agent 43 is selected from SYLGARD silicone elastomer manufactured by Dow Corning, and the two components are mixed evenly in a ratio of 10:1.

[0086] S52. Control the liquid level of the mixture 43 of liquid PDMS and curing agent added to the petri dish 42 to 3 mm above the upper surface of the channel mold, and let it stand for 20 min.

[0087] In a specific implementation, as a preferred embodiment of the present invention, in step S6, after curing PDMS in an oven, the solid PDMS is peeled off from the mold to obtain a flexible microchannel, including:

[0088] S61. Place the culture dish 42 together with the microchannel mold 41 and the mixture 43 of liquid PDMS and curing agent in an oven to turn the mixture 43 of liquid PDMS and curing agent into solid PDMS. In this embodiment, preferably, the curing temperature is 80-120°C and the curing time is 30-80 min during the curing process.

[0089] S62. Remove the microchannel fabrication device from the oven and allow it to cool to room temperature;

[0090] S63. Use the L-shaped peeling method to peel the solid PDMS from the microchannel template; in this embodiment, preferably, wrap the solid PDMS with plastic wrap to prevent its surface from being contaminated and affecting the next step of the operation.

[0091] S64. Drill holes in the solid PDMS at the liquid storage tank to serve as the liquid inlet and outlet;

[0092] S65. Solid PDMS 51 and glass slide 52 are placed together in a plasma cleaner for oxygen plasma surface treatment; in this embodiment, preferably, the plasma treatment time is set to 1 to 3 minutes.

[0093] S66. Remove the solid PDMS 51 and the glass slide 52 from the plasma cleaning agent and attach them together to obtain a microchannel 53 with a smooth inner surface and excellent sealing performance. Figure 5 As shown.

[0094] 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 preparing flexible microchannels, characterized in that, Flexible microchannels are fabricated using photoresist-assisted 3D printing, including: The channel model was created using a computer, and the microchannel template was printed using a 3D printer, including: Use computer-aided design software to design and draw microchannel template drawings; Import the drawn microchannel template drawing into the slicing software in .stl file format for slicing processing; Set the exposure parameters; Use an SLA printer to print the microchannel template; Clean the surface of the printed microchannel template, including: Soak the 3D-printed microchannel template in 95% alcohol for 10-20 minutes; The microchannel template was ultrasonically vibrated for 3-5 minutes to remove any uncured material remaining on the surface of the microchannel template. Photoresist is spin-coated onto the upper surface of the cleaned microchannel template, including: The microchannel template, after surface cleaning, is adsorbed onto a spin coater under vacuum negative pressure. Photoresist is then spin-coated onto the surface of the microchannel template to ensure that the photoresist evenly covers the surface of the microchannel template. A smooth microchannel mold was obtained by curing the photoresist using an ultraviolet light exposure machine. A mixture of liquid PDMS and curing agent is poured into a smooth microchannel mold; After curing PDMS in an oven, the solid PDMS is peeled off from the mold to obtain flexible microchannels.

2. The method for preparing flexible microchannels according to claim 1, characterized in that, The method of curing photoresist with an ultraviolet light exposure machine to obtain a smooth microchannel mold includes: After spin coating the photoresist, the microchannel template is placed in an ultraviolet exposure machine to cure the spin-coated photoresist. After exposure, the microchannel template is removed from the UV exposure machine to obtain a smooth microchannel mold.

3. The method for preparing flexible microchannels according to claim 1, characterized in that, The process of casting a mixture of liquid PDMS and curing agent onto a smooth microchannel mold includes: A smooth microchannel mold is fixed in a petri dish, and a mixture of liquid PDMS and curing agent is added to the petri dish; The liquid PDMS and curing agent mixture added to the petri dish was kept at a height of 3 mm from the upper surface of the channel mold, and left to stand for 20 min.

4. The method for preparing flexible microchannels according to claim 1, characterized in that, After curing PDMS in an oven, the solid PDMS is peeled off from the mold to obtain flexible microchannels, including: The petri dish, along with the microchannel mold and the PDMS and curing agent mixture, was placed in an oven to transform the liquid PDMS and curing agent mixture into solid PDMS. Remove the microchannel fabrication device from the oven and allow it to cool to room temperature; The solid PDMS was peeled off from the microchannel template using an L-shaped peeling method; Holes are punched in the solid PDMS reservoir to serve as the inlet and outlet for the liquid; Solid PDMS and glass slides were placed together in a plasma cleaner for oxygen plasma surface treatment. Solid PDMS and glass slides were removed from the plasma cleaning agent and bonded together to obtain a microchannel with a smooth inner surface and excellent sealing performance.

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