A manufacturing process method for a three-dimensional micro-mixer

Abstract

The application discloses a manufacturing process method of a three-dimensional micro-mixer, which can realize fast and efficient mixing and reaction between different working substances. The manufacturing process comprises four main process steps of designing a structure mask plate, designing a positioning mask plate, assembling the mask plate and a stainless steel rod and a micro-channel mold, and manufacturing a chip main body. The manufacturing process is simple, low in cost, does not need professional equipment and is easy to process. The three-dimensional micro-mixer manufactured by the application fully utilizes the space of the micro-fluidic chip, the mixing chamber fully utilizes the secondary flow generated by the three-dimensional structure, the mixing efficiency is improved, and the whole micro-mixer reaches the purpose of high mixing efficiency.

Description

Technical Field

[0001] This invention relates to the field of microfluidic devices, and in particular to a manufacturing process for a three-dimensional micromixer. Background Technology

[0002] Micromixers are the most common and, more importantly, the most fundamental functional component in microfluidic chip systems. Their function is to homogenize fluids of different properties in a short time, forming the basis of all biochemical reactions. The quality of microfluidic mass transfer and mixing characteristics directly determines the performance and efficiency of fluid-centric biochemical reaction systems.

[0003] Commonly used microfluidic chip fabrication processes both domestically and internationally primarily utilize materials such as silicon, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA, or acrylic), and glass capillaries. These processes employ techniques including photolithography, soft photolithography, molding, imprinting, micromachining, etching, and 3D printing. The manufacturing cycle is long, production requires specialized equipment and environments, and costs are relatively high. Traditional methods mainly use PMMA as the substrate material, carving channels onto the substrate and then bonding two identical substrate materials together. Common bonding methods include thermal bonding and chemical bonding, but both require specialized equipment. Furthermore, many researchers both domestically and internationally are using 3D printing to fabricate micromixers. By printing soluble materials to form microchannels, complex microchannel structures can be created. However, due to limitations of the 3D printing process, the printed mold surface is often uneven, making it impossible to guarantee smooth microchannels. Additionally, the use of chemical agents to dissolve the mold often corrodes the microchannels to some extent. Summary of the Invention

[0004] This invention proposes a low-cost, efficient and convenient manufacturing process for three-dimensional micromixers, aiming to reduce the processing requirements and costs of traditional microchannels and to fabricate three-dimensional micromixers using relatively simple equipment.

[0005] The technical solution to achieve the above objectives is as follows: A manufacturing process for a three-dimensional micromixer, comprising:

[0006] Design and fabricate the structural mask;

[0007] Design and fabricate the positioning mask;

[0008] The micro mixer mold is formed by assembling a structural mask, a stainless steel rod, and a micro-mixing chamber mold using a positioning mask.

[0009] The micro-mixer is obtained by casting a micro-mixer mold.

[0010] Furthermore, the design and fabrication of the structural mask is as follows: the structural mask is designed to be convex, and the masks are assembled by combining with each other using the convex notch portion. The size of the notch of the structural mask is the thickness of the material to be processed.

[0011] Furthermore, the design and fabrication of the positioning mask is as follows: the positioning mask is designed as a double layer, the upper layer is designed with positioning intervals, mainly responsible for ensuring the positional relationship between the stainless steel bars; the lower layer is designed with fixing bolts to maintain the stability of the casting, and the upper and lower layers are glued together, leaving a channel for placing the corresponding mold.

[0012] Furthermore, the micro-mixing chamber mold is a mold with a double helical twist structure, where each thread segment is equidistant, and the inlet is required to be flush with the position of the stainless steel rod and of equal size.

[0013] Furthermore, the assembly mask, stainless steel rod, and micro-mixer chamber mold are assembled by using a positioning mask to assemble the structural mask, stainless steel rod, and micro-mixer chamber mold, and then combining them to form a micro-mixer mold; the gap between the stainless steel rod and the micro-mixer chamber mold is connected with a suitable adhesive to maintain the flatness of the channel and the stability during subsequent pouring.

[0014] Furthermore, the method for manufacturing the chip body is as follows: a micro-mixer mold is used to solidify the chip body, resulting in a cast chip body. The stainless steel rod is then removed, and the micro-mixing chamber mold is taken out, thus forming the micro-mixer.

[0015] Compared with existing technologies, the three-dimensional micromixer proposed in this invention has the following advantages:

[0016] 1) The micro mixer of this invention has a reasonable design, simple structure, and low cost;

[0017] 2) The micro mixer of the present invention has an arc-shaped channel inside, which makes full use of the secondary flow generated by the structure in the mixing chamber, improves the mixing efficiency, and effectively improves the practicality of the micro mixer;

[0018] 3) Because the entire internal channel is circular, the contact angle between the reagent and the inner wall of the channel is 0°, and the internal channel is smooth, the contact between the reagent and the inner wall of the channel is reduced, thus reducing the formation of adhering substances.

[0019] 4) No specialized equipment is required. Circular microchannels can be formed directly by casting with PDMS, which reduces the processing requirements of microfluidic chips. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the mask structure of the micromixer of the present invention.

[0021] Figure 2 This is a schematic diagram of the mask assembly of the micromixer structure of the present invention.

[0022] Figure 3 This is a schematic diagram of the micromixing chamber mold of the micromixer of the present invention.

[0023] Figure 4 This is a schematic diagram of the positioning mask for the micro-mixer of the present invention.

[0024] Figure 5 This is a schematic diagram of the micro-mixer casting platform of the present invention.

[0025] Figure 6 This is a partially enlarged schematic diagram of the microchannel of the micromixer of the present invention. Detailed Implementation

[0026] This invention provides a manufacturing process for a three-dimensional micromixer based on microfluidic technology. The method first involves designing and fabricating a mask, the mask dimensions of which define the size of the micromixer, the channel inlet position, and the channel height. A stainless steel rod and a mold are used as templates for traditional PDMS casting, inserted into the corresponding positions on the mask, and UV adhesive is used to connect the stainless steel rod to the mold. PDMS is then cast into the mask, heated to solidify, and finally the stainless steel rod and mold are removed, thus generating the micromixer. The specific steps are as follows:

[0027] (1) Combination Figure 1 , 2 This invention designs and manufactures a specific model of a mask, which, after assembly, forms a closed rectangle. The mask is designed in a "convex" shape, and the masks are assembled by combining with each other using convex notches. The size of the notch in the mask corresponds to the thickness of the material being processed. The "convex" design facilitates the assembly of the mask and maintains the coaxiality of the through holes in the mask.

[0028] (2) Combination Figure 3 The specific model of the micro-mixing chamber used in this invention should have the same outer diameter as the stainless steel rod, and the two should be placed coaxially.

[0029] (3) Combination Figure 4 This invention designs and fabricates a specific model of a positioning mask. The upper and lower layers of the positioning mask are then glued together using UV adhesive, ensuring even application. A stainless steel rod is inserted into the concentric shaft channel. An acrylic plate is installed underneath the positioning mask as a base. When using UV adhesive, apply it to one side of the structural mask, then adhere the adhesive-coated surface of the mask to the base. Apply pressure to ensure adhesion, and irradiate the mask with ultraviolet light for 6 minutes to allow the UV adhesive to solidify. The structural mask is then positioned according to the requirements of the positioning mask.

[0030] (4) Combination Figure 5Grind both ends of the stainless steel rod with sandpaper. Clean the stainless steel rod and micromixer chamber mold with acetone using ultrasonic cleaning for 5 minutes, then soak in anhydrous ethanol and ultrasonic cleaning for 5 minutes, followed by ultrasonic cleaning with distilled water for 5 minutes. Dry and set aside. Arrange the stainless steel rod and micromixer chamber mold according to the positioning mask. At the connection points of the stainless steel rods, apply UV adhesive to the ground ends of the rods and attach them to the connection points. Irradiate the mask with ultraviolet light for 6 minutes to allow the UV adhesive to solidify.

[0031] (5) Prepare PDMS, stir evenly, place in a vacuum chamber and evacuate until no more bubbles emerge from the PDMS. Pour the PDMS into the structure mask, with the injection volume reaching the same height as the structure mask. Place the micromixer mold in a heating chamber, adjust the temperature to 70℃, and remove it after heating for 6 hours. Take out the stainless steel rod and the micromixing chamber mold.

[0032] (6) Combination Figure 6 Select a glass capillary tube with an outer diameter equal to that of the stainless steel rod. Sand both ends of the glass capillary tube smooth and apply UV adhesive to its surface. Insert the glass capillary tube into the PDMS as the inlet channel, ensuring the glass tube end is aligned with the inner wall of the channel. After alignment, irradiate the mask with ultraviolet light for 6 minutes to allow the UV adhesive to solidify. Connect the glass capillary tube to the corresponding inlet and introduce different working fluids to perform mixing.

[0033] Example

[0034] This invention proposes a manufacturing process for a three-dimensional micromixer based on microfluidic technology. The fabrication of a three-dimensional spiral micromixer is used as an example.

[0035] (1) Combination Figure 1 , 2 The structural mask is designed in a convex shape. The structural masks can be interlocked and installed by notches at both ends of the convex shape. The size of the notches corresponds to the thickness of the material being processed. The convex design facilitates the assembly of the structural masks and maintains the coaxiality of the through holes. A specific model of the structural mask is engraved on the PDMS using a laser engraving machine. The main body of the structural mask is formed by assembling mask 1, mask 2, mask 3, and mask 4. The diameter of the central hole in mask 1, mask 2, and mask 4 is 0.6 mm.

[0036] (2) Combination Figure 3 The specific model (9) of the micro-mixing chamber mold used in this invention is composed of... Figure 5 The solid line in the middle indicates that the outer diameter of the mold is 0.6 mm and the length is 30 mm. It has 11 spiral structures and is placed coaxially with the inlet channel 5.

[0037] (3) Combination Figure 4A positioning mask was designed and fabricated. The positioning mask was 8 cm x 8 cm, with a 41 mm x 21 mm rectangle left in the middle, which would be filled by the structural mask. The upper mask would have space reserved for the micromixer inlets 5 and 6 and outlet 7, in addition to some space for installing mounting devices. Two M4 bolt holes were drilled in the lower mask, tangent to the reserved inlet positions. Bolt 8 would be added later to clamp the stainless steel needle. The structural mask was assembled and fixed with a stainless steel rod. UV adhesive was applied to one side of the structural mask surface. The UV-coated structural mask body was then attached to the 8 cm x 8 cm substrate, applying pressure to ensure adhesion. The mask was then irradiated with UV light for 6 minutes to allow the UV adhesive to solidify. The stainless steel rod was then removed.

[0038] (4) Grind both ends of the stainless steel rod with 1000-grit sandpaper. Clean the smoothed stainless steel rod with acetone using ultrasonic cleaning for 5 minutes, then soak it in anhydrous ethanol and ultrasonic cleaning for 5 minutes, and finally ultrasonic cleaning it with distilled water for 5 minutes. Blow dry and set aside. Arrange the stainless steel rods in a layout. At the joint of the stainless steel rods, apply UV adhesive to the smoothed ends of the stainless steel rods and attach them to the joint. Irradiate the mask with ultraviolet light for 6 minutes to allow the UV adhesive to solidify.

[0039] (5) Prepare PDMS at a ratio of 10:1, stir evenly, place in a vacuum chamber and evacuate until no more bubbles emerge from the PDMS. Pour the PDMS into the mask body, with the injection height consistent with the height of the structural mask. Place the micromixer mold in a heating chamber, adjust the temperature to 55℃, and after heating for 12 hours, remove the PDMS chip, remove the stainless steel rod and glass capillary to generate a T-shaped microchannel, remove the micromixing chamber mold, and generate the micromixer.

[0040] (6) Combination Figure 6 Select a glass capillary tube with an outer diameter of 0.6 mm and grind both ends of the capillary tube flat with 1000-grit sandpaper. Apply UV adhesive to the surface of the glass capillary tube 5 mm from the end. Insert the glass capillary tube into the PDMS inlet channel, ensuring the end of the glass tube is aligned with the inner wall of the channel. After alignment, irradiate with ultraviolet light for 6 minutes to allow the UV adhesive to solidify. Connect the glass capillary tube to the corresponding inlet and introduce different working fluids to begin mixing.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A manufacturing process for a three-dimensional micromixer, characterized in that, include: Design and manufacture structural mask plates, specifically: design the structural mask plates as convex, and install the mask plates by combining them with the convex notch parts. The size of the notch in the structural mask plate is the thickness of the material to be processed. The positioning mask was designed and manufactured as follows: the positioning mask was designed as a double layer. The upper layer was designed with positioning intervals to ensure the positional relationship between the stainless steel rods. The upper mask will reserve space for the inlet and outlet of the micro mixer. In addition, some space will be reserved for the installation of fixing devices. The lower mask is designed with fixing bolts to clamp the stainless steel rods. The upper and lower layers are glued together, leaving a channel for placing the micro mixing chamber mold. The micro mixer mold is formed by assembling a structural mask, a stainless steel rod, and a micro-mixing chamber mold using a positioning mask. The micro-mixing chamber mold is a mold with a double-helix twisted structure, where each thread segment is equidistant, and the inlet is flush with and equal in size to the stainless steel rod. The assembly structure mask, stainless steel rod, and micro-mixer chamber mold are assembled using a positioning mask, and the micro-mixer mold is combined to form the micro-mixer mold. The gap between the stainless steel rod and the micro-mixing chamber mold is connected with adhesive. The micro-mixer is obtained by casting a micro-mixer mold.

2. The manufacturing process of a three-dimensional micromixer according to claim 1, characterized in that, The upper and lower layers of the positioning mask are bonded together with UV adhesive.

3. The manufacturing process of a three-dimensional micromixer according to claim 1, characterized in that, Grind both ends of the stainless steel rod with sandpaper, ultrasonically clean the stainless steel rod and the micro mixer chamber mold with acetone for 5 minutes, then ultrasonically clean them with anhydrous ethanol for 5 minutes, and finally ultrasonically clean them with distilled water for 5 minutes.

4. The manufacturing process of a three-dimensional micromixer according to claim 1, characterized in that, The process of obtaining a micro mixer by casting a micro mixer mold involves: casting the micro mixer mold, waiting for the chip body to solidify, obtaining the cast chip body, pulling out the stainless steel rod, removing the micro mixing chamber mold, and thus forming the micro mixer.

5. The manufacturing process of a three-dimensional micromixer according to claim 4, characterized in that, The casting method is as follows: Prepare PDMS, stir it evenly, place it in a vacuum chamber and evacuate it until no bubbles emerge from the PDMS; pour the PDMS into the mask body, and the injection height is consistent with the height of the structural mask; place the micro mixer mold in a heating box, adjust the temperature to 55℃, and after heating for 12 hours, take out the PDMS chip, take out the stainless steel rod and glass capillary to generate a T-shaped microchannel, take out the micro mixing chamber mold to generate the micro mixer.

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