Polymer micro-fluidic chip surface modification method and processing device

Abstract

The invention relates to the technical field of micro-fluidic chip manufacturing and surface modification, in particular to a modification method and a treatment device for the surface of a polymer micro-fluidic chip. The method for modifying the surface of the polymer micro-fluidic chip comprises the steps that a flame shielding cover with an opening is fixed to the surface of the polymer micro-fluidic chip to be treated, and the shape of the opening of the flame shielding cover corresponds to the shape of a to-be-treated area of the chip, so that the to-be-treated area of the chip can be exposed through the opening; the face, covered with the flame shielding cover, of the chip faces flames, the chip assembly and the flames are controlled to move relatively, and the flames are used for scanning the to-be-processed area on the surface of the chip; and after the treatment is completed, cooling and removing the flame shielding cover to obtain the modified chip. According to the method, the chip micro-channel can be accurately modified, the hydrophilicity of the micro-channel is remarkably improved, and the device is simple in structure and low in cost.

Description

Technical Field

[0001] This invention relates to the field of microfluidic chip manufacturing and surface modification technology, specifically to a method and apparatus for modifying the surface of a polymer microfluidic chip. Background Technology

[0002] Polymer microfluidic chips are widely used in bioanalysis, chemical reactions, and other fields due to their low cost and ease of fabrication. However, most polymer materials commonly used in microfluidic chips (such as polydimethylsiloxane PDMS, polymethyl methacrylate PMMA, and cyclic olefin copolymers COC) have a certain degree of hydrophobicity on their surfaces, which affects liquid flow and sample loading. This makes them almost unusable in applications requiring hydrophilic surfaces, such as droplet microfluidic chips and self-driven microfluidic chips. Therefore, it is necessary to modify the surface of polymer microfluidic chips to be hydrophilic to meet the needs of various applications, including fluid actuation, droplet generation, and surface chemical grafting.

[0003] Existing surface treatment methods for polymer microfluidic chips are mainly divided into physical and chemical methods, such as oxygen plasma treatment, corona treatment, laser scanning, chemical etching, vapor deposition, and chemical grafting. These methods generally suffer from problems such as complex and expensive processing equipment, limited processing area, low adaptability to different materials, high processing costs, and easy induction of material deformation during the processing. Summary of the Invention

[0004] The present invention aims to provide a method and apparatus for modifying the surface of polymer microfluidic chips. The method can modify the surface of polymer microfluidic chips to be hydrophilic, while solving the problems of complex and expensive processing equipment and high processing cost in the existing process.

[0005] To address the aforementioned technical problems, this invention provides a method for modifying the surface of a polymer microfluidic chip, comprising the following steps: The surface of the polymer microfluidic chip to be treated is cleaned; A flame shield with an opening is fixed to the surface of the chip to form a chip assembly; the shape of the opening of the flame shield corresponds to the shape of the area to be processed on the chip, so that the opening can expose the area to be processed on the chip, and the other areas of the flame shield can cover the areas of the chip that do not need to be processed. The chip assembly is placed above the flame, with the side of the chip covered by the flame shield facing the flame. The relative movement between the chip assembly and the flame is controlled, and the flame is used to scan the area to be processed on the chip surface. After processing, the chip assembly is cooled, the flame shield is removed, and the modified chip is obtained.

[0006] Furthermore, the polymer microfluidic chip is made of at least one of polymethyl methacrylate, polycarbonate, polypropylene, cyclic olefin copolymer, cyclic olefin polymer, and polydimethylsiloxane.

[0007] Furthermore, the distance between the chip surface to be processed and the outer flame of the flame is 1 cm to 10 cm, the relative motion speed is 1 cm / s to 10 cm / s, and the number of scans is 5 to 20.

[0008] Furthermore, after the flame modification treatment, the water contact angle on the surface of the polymer microfluidic chip is no greater than 30 degrees.

[0009] Furthermore, after the processing is completed, the cooling chip is placed in an inert gas for cooling.

[0010] Furthermore, the flame shield is made of a high-temperature resistant material.

[0011] Furthermore, the high-temperature resistant material is stainless steel plate or polyetheretherketone.

[0012] Furthermore, the thickness of the flame shield is 0.3-0.5 mm.

[0013] The present invention also provides a processing apparatus for implementing the above method, comprising: Base; A flame generating unit is mounted on the base; A chip fixing mechanism is disposed on the base for fixing the chip assembly. A driving mechanism, disposed in the flame generating unit or the chip fixing mechanism, is used to drive the flame generating unit and the chip assembly to move relative to each other.

[0014] Furthermore, the program control unit can preset and control the distance between the chip surface and the flame, the distance the chip moves relative to the flame, the moving speed, and the number of moves.

[0015] The beneficial effects of this invention are: (1) The method of the present invention uses flame modification, which can complete hydrophobic modification in a short time, resulting in a significant decrease in the contact angle of the polymer microfluidic chip and a significant increase in hydrophilicity. In addition, the equipment provided by the present invention is simple, fast, efficient and low cost.

[0016] (2) By designing a dedicated flame shield, precise and selective hydrophilic modification of specific areas (such as microchannel areas) on the surface of polymer microfluidic chips is achieved, while protecting the untreated areas and avoiding problems caused by overall processing.

[0017] (3) The method of the present invention has wide applicability to different polymer materials (such as PMMA, PC, COC, PDMS, etc.), and the hydrophilicity of the treated surface is significantly improved, and the water contact angle can be stably reduced to below 30 degrees, which greatly improves the application performance of the chip in the fields of biology and chemistry.

[0018] (4) The processing device provided by the present invention has a simple structure, low cost, and is easy to automate the entire processing process. It ensures the precise control of process parameters (distance, speed, number of times) and consistency between batches. It has good scalability and process compatibility and is suitable for large-scale industrial production applications. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the combination of a chip and a flame shield according to one embodiment of the present invention; Figure 2 This is a schematic diagram of the chip surface modification treatment apparatus according to one embodiment of the present invention; Figure 3 This is a comparison chart of the contact angle test before and after the chip modification treatment of this invention.

[0020] In the figure: 11. Flame shield opening; 12. Microchannel; 13. Flame shield; 14. Polymer microfluidic chip; 21. Drive mechanism; 22. Flame; 23. Chip assembly; 24. Base. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in specific embodiments of this invention will be described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0022] The polymer microfluidic chip 14 of this invention refers to a device made of high molecular polymer as the matrix material, manufactured through precision processing technology, and integrating micron-scale channels and structures internally. It manipulates fluids through a microchannel network to achieve functions such as sample preparation, reaction, separation, and detection.

[0023] The polymer matrix material that can be modified by the method of the present invention is at least one of polymethyl methacrylate (PMMA), polycarbonate (PC), polypropylene (PP), cyclic olefin copolymer (COC), cyclic olefin polymer (COP), and polydimethylsiloxane (PDMS).

[0024] The method for modifying the surface of the polymer microfluidic chip of the present invention specifically includes the following steps: Step 1: Remove impurities from the surface of the polymer microfluidic chip to be treated.

[0025] Methods for removing impurities from the surface of chip 14 can employ one or more of conventional chemical solvent cleaning, physical cleaning, or gas purging. For example, chemical solvent cleaning can use solvents such as deionized water, ethanol, isopropanol, and acetone to immerse and ultrasonically clean the chip, effectively dissolving and removing organic impurities. Physical cleaning methods can employ plasma treatment or ultraviolet ozone irradiation. Gas purging can use clean, dry compressed air, nitrogen, or other inert gases to purge the chip surface to remove liquid residues and particulate matter. In one specific embodiment of the invention, this step involves rinsing the chip with pure water, followed by ultrasonic treatment with an isopropanol aqueous solution, and then drying it.

[0026] Step 2: Fix a flame shield 13 with an opening on the surface of the chip 14 to form a chip assembly; the shape of the flame shield opening 12 corresponds to the shape of the area to be processed on the chip, so that the opening 12 can expose the area to be processed on the chip 14, and the other areas of the flame shield 13 can cover the areas of the chip that do not need to be processed.

[0027] The purpose of using the flame shield 13 in this invention is to achieve precise modification treatment while protecting the original hydrophobic properties of other areas on the chip 14 to meet the functional requirements of the complex chip, and to prevent thermal deformation, degradation, or contamination of these areas due to the high temperature of the flame. Therefore, the flame shield 13 needs to be made of a high-temperature resistant material, such as a high-temperature resistant metal or thermoplastic material. In some specific embodiments of this invention, the flame shield 13 is preferably made of stainless steel or polyetheretherketone (PEEK).

[0028] like Figure 1 As shown, the shape of the opening 11 on the flame shield 13 corresponds to the shape of the area to be processed on the chip (usually referring to the microchannel 12). That is, the projection of the opening 11 on the chip coincides with the microchannel 12, ensuring that the opening 11 just exposes the microchannel 12 while shielding areas that do not require processing. It is understandable that certain process errors will exist during actual manufacturing; these errors should be controlled to below 1% to minimize the impact of the flame on other areas. The processing method for the flame shield opening 11 is unrestricted, including but not limited to laser processing, wire cutting, and CNC machining. It should be noted that the shape of the opening 11 on the flame shield is determined by the shape of the corresponding chip microchannel; for chips with microchannels of the same shape, the flame shield can be reused.

[0029] In some specific embodiments of the present invention, the thickness of the flame shield 13 is 0.3-0.5 mm. This thickness range is sufficient to block the flame from directly impacting the non-processed area, effectively avoiding the adverse effects of high temperature on the non-processed area, while ensuring that the flame shield 13 has sufficient structural rigidity and strength, and is not easily bent or deformed during repeated use and fixing, thereby maintaining a tight fit with the chip surface.

[0030] There are various ways to fix the chip 14 and the flame shield 13, such as clamping, bonding, snapping, magnetic attraction, etc. In some specific embodiments of the present invention, clamping is preferred because it is simple to operate and the two can be easily separated after processing.

[0031] Step 3: Place the chip assembly 23 above the flame, with the side of the chip covered by the flame shield facing the flame, control the relative movement between the chip and the flame, and use the flame to scan the area to be processed on the chip surface.

[0032] like Figure 2 As shown, the chip with the flame shield facing down, and the chip assembly 23 can be fixed using conventional fixing mechanisms such as brackets or clamps. The flame generating unit is used to generate flame 22, and a common industrial flame gun can be used. The flame fuel source can be acetylene, butane, propane, or natural gas, etc. The flame generating unit can be fixed using brackets or other means.

[0033] To ensure the modification effect, the distance between the chip microchannel surface and the outer flame of the flame needs to be adjusted so that the flame can effectively perform high-temperature treatment on the chip surface. In some specific embodiments of the present invention, the distance between the chip microchannel surface and the outer flame of the flame is preferably 1 cm to 10 cm, the relative speed between the chip assembly and the flame is 1 cm / s to 10 cm / s, and the number of scans is 5 to 20. Under these conditions, surface hydrophilization can be reliably achieved without damaging the chip structure.

[0034] To facilitate flame scanning of the chip assembly, this invention includes a driving mechanism 21 on the chip fixing mechanism or the flame generating unit, enabling relative movement between the chip assembly 23 and the flame 22. For example, a driving mechanism can be installed on the flame generating unit, allowing the flame 22 to move back and forth along the microchannels to scan the chip microchannels; alternatively, a driving mechanism can be installed on the chip fixing mechanism, allowing the chip microchannels to move back and forth with the flame to receive flame scanning. In some specific embodiments of this invention, the driving mechanism may further include a program control unit, which can preset and control the distance between the chip surface and the flame, the relative movement distance between the chip assembly and the flame, the movement speed, and the number of scans, thereby achieving automated scanning processing.

[0035] Step 4: After processing, cool the chip assembly, remove the flame shield, and obtain the modified chip.

[0036] Chip assembly cooling can be performed in air or an inert gas environment. Flame treatment introduces a large number of hydrophilic groups onto the polymer surface, significantly reducing the water contact angle and increasing hydrophilicity. However, in an air environment, its thermodynamic state is unstable, and the contact angle gradually returns to its pre-treatment level. Cooling in an inert gas (such as nitrogen) slows down the rate of contact angle recovery, thus prolonging the duration of the hydrophilic effect. Therefore, cooling in an inert gas environment (such as nitrogen) is preferred.

[0037] The flame shield of this invention is used to implement the above-described method for modifying the surface of a polymer microfluidic chip. Its specific structure, materials, and dimensions have been described above and will not be repeated here.

[0038] The processing apparatus of this invention is used to implement the above-described method for modifying the surface of a polymer microfluidic chip, as described above. Figure 2 Specifically, it may include a base 24, a flame generating unit, a chip fixing mechanism, and a driving mechanism; the flame generating unit is disposed on the base; the chip fixing mechanism is disposed on the base and is used to fix the chip assembly. The driving mechanism is disposed on the flame generating unit and is used to drive the flame generating unit to move along the chip microchannel, thereby performing scanning processing on the chip.

[0039] like Figure 2 As shown, the base 24 in this embodiment includes a base and a support mounted on the base. The flame generating unit can be fixed to the base of the base, and the chip fixing mechanism is fixed to the support of the base. Of course, the base can also be of other shapes or structures, and the present invention does not impose specific limitations on this. The structure, installation, and function of the flame generating unit, the chip fixing mechanism, and the driving mechanism have been described above and will not be repeated here.

[0040] The following section uses the modification process of PMMA polymer microfluidic chips as an example to illustrate a specific modification process: Step 1: Rinse the 1mm thick PMMA chip (containing microchannel structure) after injection molding with pure water, then treat it with 10% isopropanol aqueous solution in ultrasound for 10 minutes, and then dry it with clean compressed air.

[0041] Step 2: Use a dovetail clamp to clamp the PMMA chip to the flame shield to obtain the chip assembly, so that the opening of the flame shield exposes the microchannel structure.

[0042] Step 3: Install the chip assembly, consisting of the PMMA chip and the flame shield, onto the fixing mechanism, with the flame shield facing downwards. Install the flame gun below the chip assembly, adjusting the distance between the PMMA chip and the outer flame to 5cm. Set the flame scanning speed in the drive device to 8cm / s and the number of scans to 10. Ignite the flame gun in the device, activate the drive program, and the flame generation unit scans ten times. The microfluidic chip, protected by the flame shield, undergoes ten scans on the surface of the flame gun.

[0043] Step 4: Allow the chip to cool naturally to room temperature in a nitrogen atmosphere, then separate the flame shield from the chip to obtain the modified chip.

[0044] To illustrate the modification effect of this invention, a contact angle meter was used to test the contact angle between a pure water droplet and the microchannel surface of the chip in this embodiment before and after treatment. Figure 3 As shown, after flame treatment, the contact angle of the chip decreased from 80 degrees to below 30 degrees, significantly improving its hydrophilicity. This method can reduce the contact angle to below 30 degrees for all polymer materials described in this invention, including PMMA, PC, PP, COC, COP, and PDMS, demonstrating good process stability.

[0045] 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 modifying a surface of a polymer microfluidic chip, characterized by, The method comprises the following steps: cleaning the surface of the polymer microfluidic chip to be treated; fixing a flame shield with an opening on the chip surface to form a chip assembly; the opening shape of the flame shield corresponds to the shape of the chip area to be treated, so that the opening can expose the chip area to be treated, and the other area of the flame shield can cover the chip area not to be treated; placing the chip assembly above the flame, and making the side of the chip covered with the flame shield face the flame, controlling the relative movement between the chip assembly and the flame, and scanning and treating the chip surface area to be treated by the flame; after the treatment is completed, cooling the chip assembly, removing the flame shield, and obtaining the modified chip.

2. The method of modifying a surface of a polymer microfluidic chip according to claim 1, wherein The material of the polymer microfluidic chip is at least one of polymethyl methacrylate, polycarbonate, polypropylene, cyclic olefin copolymer, cyclic olefin polymer, and polydimethylsiloxane.

3. The method of modifying the surface of a polymer microfluidic chip according to claim 1, wherein The distance between the chip surface to be treated and the outer flame is 1-10 cm, the relative movement speed between the chip assembly and the flame is 1-10 cm / s, and the scanning times are 5-20.

4. The method of modifying the surface of a polymer microfluidic chip according to claim 1, wherein After the flame modification treatment, the water contact angle of the surface of the polymer microfluidic chip is not greater than 30 degrees.

5. The method of claim 1, wherein the polymer microfluidic chip surface is a polydimethylsiloxane (PDMS) surface. After the treatment is completed, the cooled chip assembly is placed in an inert gas for cooling.

6. The method of modifying the surface of a polymer microfluidic chip according to claim 1, wherein The flame shield is made of high-temperature resistant material.

7. The method of modifying the surface of a polymeric microfluidic chip according to claim 6, wherein The high-temperature resistant material is stainless steel plate or polyether ether ketone.

8. The method of modifying the surface of a polymer microfluidic chip according to claim 1, wherein The thickness of the flame shield is 0.3-0.5 mm.

9. A processing device for implementing the method of claim 1, characterized by It comprises: a base; a flame generating unit arranged on the base; a chip fixing mechanism arranged on the base for fixing the chip assembly of claim 1; a driving mechanism arranged on the flame generating unit or the chip fixing mechanism for driving the relative movement of the flame generating unit and the chip assembly.

10. The treatment device of claim 9, wherein the driving mechanism comprises a program control unit capable of presetting and controlling the distance between the chip surface and the flame, the relative movement distance of the chip assembly and the flame, the movement speed, and the scanning times.

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