Micro-fluidic chip surface microstructure forming method

Abstract

The invention provides a micro-fluidic chip surface microstructure forming method. The method includes cleaning the surface of a polymer substrate; mixing a silane coupling agent with nanoparticles, coating the surface of a polymer substrate with the mixed solution, and drying; the mold is fixed to the upper heating plate, and the mold, the upper heating plate and the lower heating plate are heated; and putting the polymer substrate on a lower heating plate, directly pressurizing and maintaining the pressure, directly demolding after releasing the pressure, and cooling to obtain the surface microstructure of the polymer substrate. According to the micro-fluidic chip surface microstructure forming method, the forming temperature of the polymer substrate is reduced through polymer substrate surface cleaning and silane nano coating, meanwhile, direct pressurization and demolding at the forming temperature are allowed, repeated heating and cooling are not needed, the hot pressing time is shortened, and the production efficiency is improved. The rapid hot press molding of the micro-fluidic chip surface microstructure is realized, and the production efficiency is improved. The method has the characteristics of simplicity and convenience in operation, high efficiency, easiness in implementation and the like, and has higher practical application value.

Description

Technical Field

[0001] This invention relates to the field of microfluidic chip manufacturing, and more particularly to a method for forming microstructures on the surface of a microfluidic chip. Background Technology

[0002] Microfluidic chips are chips that enable controllable fluid flow. They offer advantages such as small size, high integration, strong controllability, and rapid response, and are widely used in medical diagnostics, cell separation, drug delivery, virus testing, and nanomaterial synthesis. Microfluidic chips mainly consist of a substrate and a cover plate (made of materials such as polymethyl methacrylate, polydimethylsiloxane, and glass). The substrate contains functional units such as microchannels and microstructures, while the cover plate contains inlets and detection windows. The microchannels and microstructures on the substrate surface are crucial for achieving controllable fluid flow; their dimensions are typically tens to hundreds of micrometers wide, requiring sophisticated manufacturing methods and processes.

[0003] Methods for manufacturing microstructures on substrate surfaces include photolithography, CNC machining, hot pressing, molding, injection molding, and laser etching. Hot pressing is one of the commonly used methods for forming microstructures on polymer substrate surfaces. Its principle involves heating the polymer substrate to soften it, applying pressure to a mold and the polymer substrate, causing the polymer material to fill and replicate the structure on the mold. After cooling and demolding, a polymer substrate with microstructures is obtained. This method offers high forming accuracy and is simple to operate, possessing great potential for large-scale production of microfluidic chips. However, during hot pressing, the polymer substrate and mold require repeated heating and cooling, resulting in a long hot pressing cycle, which significantly reduces the efficiency of hot pressing microstructures on microfluidic chip surfaces. Simultaneously, cooling and demolding cause springback of the surface microstructures, reducing the forming accuracy. While increasing temperature and pressure can usually shorten the forming time, it exacerbates the springback deformation of the microstructures, increasing the required cooling time. Therefore, the hot pressing method for forming microstructures on microfluidic chip surfaces needs further improvement to enhance both the forming efficiency and accuracy. Summary of the Invention

[0004] To address the above problems, this invention provides a method for forming microstructures on the surface of microfluidic chips. By using plasma cleaning combined with a silane nano-coating, the hot pressing temperature of microstructures on the polymer substrate surface can be reduced, the heating and holding time can be shortened, demolding can be allowed at the hot pressing temperature, and the springback of the hot-pressed microstructures can be suppressed, thereby improving the accuracy and efficiency of hot pressing microstructures on the polymer substrate surface.

[0005] The technical solution of this invention is as follows: a method for forming microstructures on the surface of a microfluidic chip, comprising the following steps:

[0006] Step (1) Cleaning and coating preparation of polymer substrate surface: The surface of the polymer substrate is cleaned using plasma at a power of 700-900W, a speed of 50-70mm / s, and a distance of 4-10mm. 0-50g of nanoparticles are added to 0.5-100g of silane coupling agent, and the mixture is magnetically stirred at room temperature for 5-30min, followed by ultrasonic vibration for 5-30min to obtain a homogeneous mixture of silane coupling agent and nanoparticles. The mixture is then uniformly coated onto the surface of the polymer substrate and dried at 60-100℃ to obtain a polymer substrate with a silane nanoparticle coating.

[0007] Step (2) Rapid hot pressing of polymer substrate surface microstructure: Fix the mold on the upper heating plate and heat the upper and lower heating plates and the mold to 100~120℃. Place the polymer substrate on the lower heating plate, apply a pressure of 1-15MPa to the mold and the polymer substrate, and hold the pressure for 3~5min. After depressurization, demold the polymer substrate, take it out, and after cooling, obtain a polymer substrate with microstructure.

[0008] Furthermore, the polymer substrate in step (1) is a thermoplastic polymer material, including polymethyl methacrylate, with a thickness of 0.1~5mm.

[0009] Furthermore, the silane coupling agent in step (1) includes γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and methacryloyloxypropyltrimethoxysilane.

[0010] Furthermore, the nanoparticles mentioned in step (1) are nanoparticles with a particle size of 1~100nm, including aluminum oxide, silicon dioxide and zinc oxide.

[0011] Furthermore, the thickness of the silane nanoparticle coating on the surface of the polymer substrate in step (1) is 0.1~2μm.

[0012] Furthermore, the mold material mentioned in step (2) includes materials such as metal and silicon.

[0013] Furthermore, the pressure applied in step (2) is applied directly after the polymer substrate is placed in the substrate.

[0014] Furthermore, the demolding in step (2) is direct demolding at the molding temperature.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention optimizes the traditional hot-press molding process for microstructures on the surface of microfluidic chips. By cleaning the polymer substrate surface and applying a silane nano-coating, the molding temperature of the polymer substrate is reduced, allowing direct pressurization and demolding at the molding temperature without repeated heating and cooling, thus shortening the hot-pressing time and achieving rapid hot-press molding of microstructures on the surface of microfluidic chips, improving production efficiency. In this invention, the silane nano-coating suppresses microstructure deformation caused by cooling springback, improving the molding accuracy of microstructures on the polymer substrate surface. This invention is a simple, efficient, and easy-to-implement method for molding microstructures on the surface of microfluidic chips. Attached Figure Description

[0016] Figure 1 This is Example 1 of the present invention, namely the preparation of a coating on a polymethyl methacrylate substrate and the process of microstructure forming.

[0017] Figure 2 This is a cross-sectional view of the microchannel formed by hot pressing on the surface of polymethyl methacrylate without the use of silane nanocoating.

[0018] Figure 3 Image of micropillars formed by hot pressing on a polymethyl methacrylate surface without the use of a silane nanocoating.

[0019] Figure 4 This is a cross-sectional view of the microchannels formed by hot pressing on the surface of polymethyl methacrylate when using a silane nanocoating.

[0020] Figure 5 Image of micropillars formed by hot pressing on a polymethyl methacrylate surface using a silane nanocoating.

[0021] In the figure: 1-Silane coupling agent, 2-Nanoparticles, 3-Polymer substrate coated with mixture, 4-Polymer substrate with coating, 5-Upper heating plate, 6-Mold, 7-Lower heating plate, 8-Polymer substrate with surface microstructure. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are all for the purpose of better describing the process scheme of the present invention. Modifications to the present invention in various equivalent forms without departing from the principle of the present invention fall within the scope defined by the appended claims. Example

[0023] The specific process of microstructure formation on the surface of the microfluidic chip in this example is as follows: Figure 1 As shown, the polymer substrate is a 1 mm thick polymethyl methacrylate sheet, the silane coupling agent is γ-glycidyl etheroxypropyltrimethoxysilane, and the nanoparticles are alumina with a particle size of 10 nm.

[0024] Step (1) Preparation of the mixture of silane coupling agent and nano alumina. Weigh a certain amount of silane coupling agent 1 and nano alumina 2 and add them to a beaker. Stir the mixture at 1000 r / min for 10 min and sonicate for 5 min to mix the silane coupling agent and nano alumina evenly.

[0025] Step (2) Cleaning and coating preparation of the polymethyl methacrylate (PMMA) substrate surface. The PMMA substrate surface was cleaned using plasma at a power of 900 W, a speed of 60 mm / s, and a distance of 7 mm. The mixture was then uniformly coated onto the PMMA substrate surface, resulting in a PMMA substrate 3 with the mixture on its surface. The PMMA substrate 3 was then treated at 60°C for 60 min to obtain a PMMA substrate 4 with a surface coating.

[0026] Step (3) Hot pressing of the polymethyl methacrylate substrate surface microstructure. Fix the mold 6 on the upper heating plate 5, and heat the upper heating plate 5, mold 6, and lower heating plate 7 to 105°C. Place the polymethyl methacrylate substrate 4 on the lower heating plate 7, and apply a pressure of 10 MPa directly to the mold 6 and the polymer substrate 4, holding for 5 minutes. After depressurization, demold directly, remove the polymer substrate, and after cooling, obtain the polymethyl methacrylate substrate 8 with surface microstructure.

[0027] Under the hot-pressing conditions of Example 1, before using the silane nano-coating, the microchannel cross-section and micropillars formed by hot-pressing the polymethyl methacrylate surface are as follows: Figure 2 and Figure 3 As shown. After applying a silane nanocoating, the microchannel cross-section and micropillars formed by hot pressing on the surface of polymethyl methacrylate are respectively as shown in the figures. Figure 4 and Figure 5 As shown, the silane nanocoating significantly improves the morphology and height of hot-pressed microstructures, enabling the acquisition of microstructures with good morphology and height in a shorter time, thus improving the precision and efficiency of hot-pressing microstructures.

[0028] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be included within the scope of protection of the present invention. Furthermore, all content not described in detail in this specification is prior art known to those skilled in the art.

[0029] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. A method for forming microstructures on the surface of a microfluidic chip, characterized in that, This method is performed in the following steps: Step (1) Clean the surface of the polymer substrate, prepare a mixture of silane coupling agent and nanoparticles, coat the mixture onto the surface of the polymer substrate, and prepare a polymer substrate with a coating. Step (2) Fix the mold on the upper heating plate and heat the mold and the upper and lower heating plates. Place the polymer substrate on the lower heating plate, apply pressure and hold the pressure, release the pressure and demold, and after cooling, obtain the microstructure on the surface of the polymer substrate.

2. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, In step (1), the polymer substrate is a thermoplastic polymer material, including polymethyl methacrylate, with a thickness of 0.1~5mm.

3. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, The cleaning in step (1) is plasma cleaning, with a power of 700~900W, a speed of 50~70mm / s, and a distance of 4~10mm.

4. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, The silane coupling agent in step (1) includes γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and methacryloyloxypropyltrimethoxysilane.

5. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, In step (1), the nanoparticles are nanoparticles with a particle size of 1~100nm, including aluminum oxide, silicon dioxide and zinc oxide.

6. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, The preparation method of the silane coupling agent and nanoparticle mixture in step (1) is as follows: Take 0-50g of nanoparticles and disperse them in 0.5-100g of silane coupling agent. Stir magnetically for 5-30min at room temperature and then sonicate for 5-30min to mix evenly, so as to obtain a mixture of silane coupling agent and nanoparticles.

7. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, The preparation method of the polymer substrate surface coating in step (1) is as follows: A mixture of silane coupling agent and nanoparticles was uniformly coated onto the surface of a polymer substrate and dried at 60-100°C to obtain a silane nano-coating with a thickness of 0.1-2 μm.

8. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, In step (2), the mold is made of materials such as metal and silicon.

9. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, In step (2), the temperature of the heating plate and the mold is 100~120℃.

10. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, In step (2), pressurization and pressure holding are performed by directly pressurizing after placing the polymer substrate, with a pressure of 1-15 MPa and a pressure holding time of 3-5 min.

11. The method for forming microstructures on the surface of a microfluidic chip according to claim 1, characterized in that, In step (2), demolding is performed directly at the molding temperature.

Images