Manufacturing method of micro-fluidic chip

Abstract

The invention relates to the technical field of cell sorting and detection, in particular to a manufacturing method of a micro-fluidic chip. The manufacturing method of the micro-fluidic chip comprises the following steps: providing a substrate; forming a metal film layer on the surface of one side of the substrate; providing a cover plate, wherein the cover plate is at least provided with a micro-channel; forming an intermediate bonding layer on the substrate, wherein the intermediate bonding layer covers the surface of one side, on which the metal film layer is formed, of the substrate; performing surface activation treatment on the intermediate bonding layer; buckling a cover plate to the intermediate bonding layer, and bonding the cover plate with the substrate through the intermediate bonding layer; wherein the cover plate is a PDMS (Polydimethylsiloxane) prepolymer cover plate; the intermediate bonding layer is a silicon dioxide layer. According to the invention, the problem that the PDMS prepolymer cover plate and the metal film layer substrate are difficult to directly bond can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of cell sorting and detection, and in particular to a method for manufacturing a microfluidic chip. Background Art

[0002] Microfluidics refers to the technology of confining fluids to sub-millimeter scales to achieve precise control and manipulation of fluid behavior. Microfluidics has created powerful tools for biologists to control and simulate complete cellular microenvironments, including soluble factors that regulate cell structure, function, behavior, and growth. Microfluidic chip-based cell sorters have great potential for single-cell separation in microbiology and biotechnology, with advantages such as precise separation, disposable (thus reducing cross-contamination), ease of use, small scale, low cost, and applicability to a variety of sample sizes. Combining cell culture technology with microfluidic chips to cultivate monoclonal cell lines in independent chambers, during which fresh culture medium is continuously injected, can greatly reduce the cost and time of cell culture.

[0003] In the process of making microfluidic chips, bonding the substrate to the cover is a crucial step. The effect of bonding can directly affect the structural stability and sealing effect of the chip. In order for the substrate to provide wear resistance, corrosion resistance, reflectivity and other effects, a layer of metal film is usually set on the substrate. PDMS prepolymer has good biocompatibility, good optical transparency, high chemical stability, low cost and easy processing. It is a mainstream choice for cover sheets. However, it is more difficult to directly bond substrates such as metal or glass to PDMS prepolymer, and there are significant differences in the surface chemical properties and physical properties of the two. Direct bonding between the two usually results in weak adhesion due to interface incompatibility. Summary of the invention

[0004] The invention provides a method for manufacturing a microfluidic chip to solve the problem of difficulty in directly bonding a PDMS prepolymer cover sheet and a metal film layer substrate.

[0005] The present invention provides a method for manufacturing a microfluidic chip, comprising the following steps: providing a substrate; forming a metal film layer on one side surface of the substrate; providing a cover sheet, wherein the cover sheet is at least provided with a microchannel; forming an intermediate bonding layer on the substrate, covering the side surface of the substrate on which the metal film layer is formed; performing surface activation treatment on the intermediate bonding layer; buckling the cover sheet to the intermediate bonding layer, and bonding the cover sheet to the substrate through the intermediate bonding layer; wherein the cover sheet is a PDMS prepolymer cover sheet; and the intermediate bonding layer is a silicon dioxide layer.

[0006] Optionally, in the step of forming an intermediate bonding layer on the surface of one side of the substrate having a metal film layer, a silicon dioxide layer is formed on the surface of one side of the substrate having a metal film layer by magnetron sputtering as the intermediate bonding layer; the metal film layer covers the entire surface of the substrate thereunder, and the silicon dioxide layer covers the entire surface of the metal film layer.

[0007] Optionally, in the step of forming an intermediate bonding layer on the surface of one side of the substrate having a metal film layer, a silicon dioxide layer is formed on the surface of one side of the substrate having a metal film layer by magnetron sputtering as the intermediate bonding layer; the area of ​​the metal film layer is smaller than the area of ​​the intermediate bonding layer, and the intermediate bonding layer completely covers the metal film layer and extends beyond the range of the metal film layer to be directly connected to the substrate.

[0008] Optionally, in the step of surface activation treatment, plasma is used to bombard the intermediate bonding layer; during the plasma bombardment process, the gas used is air or oxygen; the bombardment time is 20s~120s, the power is 50W~200W, and the gas flow rate is 100μl / min. Optionally, in the step of buckling the cover sheet to the intermediate bonding layer and bonding it to the substrate through the intermediate bonding layer: placing the cover sheet at a corresponding position on the substrate, using a tool to click on the cover sheet to expel the air between the cover sheet and the substrate and tightly bond them.

[0009] Optionally, the process of air expelling and tight bonding is completed in one click; the clicking process is completed within 10 minutes after the surface activation treatment is completed; during the clicking process, the pressure applied to the surface of the cover sheet is less than or equal to 3N.

[0010] Optionally, in the step of forming the metal film layer on one surface of the substrate, the formation process includes an evaporation process.

[0011] Optionally, the method for manufacturing the microfluidic chip further includes: before the step of forming the metal film layer on the surface of one side of the substrate, pre-cleaning the substrate; the pre-cleaning process includes water washing, organic solvent cleaning or ultrasonic cleaning.

[0012] Optionally, the method for manufacturing the microfluidic chip further includes: buckling the cover sheet onto the intermediate bonding layer, bonding the intermediate bonding layer to the substrate, and then thermally baking the bonded cover sheet and the substrate to solidify the intermediate bonding layer.

[0013] Optionally, in the heat-baking step, the temperature is kept constant at 60°C to 70°C, and the heat-baking time is 10 min to 60 min.

[0014] The beneficial effects of the present invention are as follows: The manufacturing method of the microfluidic chip provided by the present invention forms a silicon dioxide layer as an intermediate bonding layer on a substrate formed with a metal film layer, and then directly bonds with a PDMS prepolymer cover sheet. Since silicon dioxide has good bonding ability with both the metal film layer and PDMS, the substrate with the metal film layer can be stably bonded with the PDMS prepolymer cover sheet. In addition, silicon dioxide has a high degree of chemical stability and inertness, is not easy to degrade, and provides a long-term stable bonding effect. At the same time, silicon dioxide is non-toxic to biological samples and can isolate the biological toxicity of some substrate materials, and is suitable for biomedical and bioanalysis applications. In addition, the silicon dioxide coating can withstand higher temperatures without degradation, and is suitable for application scenarios that require high temperature treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of a process for manufacturing a microfluidic chip according to an embodiment of the present invention; Figure 2 A schematic structural diagram of a microfluidic chip manufactured by a method for manufacturing a microfluidic chip according to an embodiment of the present invention; Figure 3 This is a photo of a microfluidic chip manufactured by the manufacturing method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The invention provides a method for manufacturing a microfluidic chip to solve the problem of difficulty in direct bonding of a DMS cover sheet and a metal film layer substrate.

[0018] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Example refer to Figure 1 This embodiment provides a method for manufacturing a microfluidic chip, comprising the following steps: providing a substrate; forming a metal film layer on one surface of the substrate; Providing a cover sheet, wherein the cover sheet is provided with at least a microfluidic channel; Forming an intermediate bonding layer on the substrate to cover the surface of the substrate on which the metal film layer is formed; performing surface activation treatment on the intermediate bonding layer; The cover sheet is buckled onto the intermediate bonding layer, and bonded to the substrate through the intermediate bonding layer; the structure of the microfluidic chip after bonding can be referred to Figure 2 shown.

[0023] Wherein, the cover sheet is a PDMS prepolymer cover sheet; and the intermediate bonding layer is a silicon dioxide layer.

[0024] The manufacturing method of the microfluidic chip provided in this embodiment forms a silicon dioxide layer as an intermediate bonding layer on a substrate formed with a metal film layer, and then directly bonds with a PDMS prepolymer cover sheet. Since silicon dioxide has good bonding ability with both the metal film layer and PDMS, the substrate with the metal film layer can be stably bonded with the PDMS prepolymer cover sheet. In addition, silicon dioxide has a high degree of chemical stability and inertness, is not easy to degrade, and provides a long-term stable bonding effect. At the same time, silicon dioxide is non-toxic to biological samples and can isolate the biological toxicity of some substrate materials, and is suitable for biomedical and bioanalysis applications. In addition, the silicon dioxide coating can withstand higher temperatures without degradation, and is suitable for application scenarios that require high temperature treatment.

[0025] Furthermore, in some embodiments, in the step of forming an intermediate bonding layer on the surface of the side having the metal film layer on the substrate, a silicon dioxide layer is formed on the surface of the side having the metal film layer on the substrate by magnetron sputtering as the intermediate bonding layer; the metal film layer covers the entire surface of the substrate thereunder, and the silicon dioxide layer covers the entire surface of the metal film layer. The use of magnetron sputtering to form the silicon dioxide layer can control the film thickness with high precision and ensure the flatness of the substrate surface.

[0026] In some other embodiments, the area of ​​the metal film layer is smaller than the area of ​​the intermediate bonding layer, and the intermediate bonding layer completely covers the metal film layer and extends beyond the range of the metal film layer to be directly connected to the substrate.

[0027] Furthermore, in some embodiments, in the step of surface activation treatment, plasma is used to bombard the intermediate bonding layer; during the plasma bombardment process, the gas used is air or oxygen. The bombardment time is 20s~120s, for example, it can be 20s, 40s, 60s, 80s, 100s, 120s; the power is 50W~200W, for example, it can be 50w, 100w, 150w, 200w; the gas flow rate is 100μl / min. Using plasma to bombard the intermediate bonding layer can activate the surface of the intermediate bonding layer, improve the hydrophilicity of the surface of the polymer material, increase the surface activity, and thus enhance the bonding strength with other materials. If the bombardment time is too low or the power is too low, the plasma layer on the surface of the polymer material will not be fully formed due to insufficient bombardment efficiency, thereby affecting the bonding effect; if the bombardment time is too long or the power is too large, the intermediate bonding layer will be completely destroyed and lose the original effect. Therefore, when the bombardment time and power are within the above range, a balance can be achieved between good bonding effect and ensuring the integrity of the intermediate bonding layer.

[0028] Furthermore, in some embodiments, in the step of buckling the cover sheet to the intermediate bonding layer and bonding the cover sheet to the substrate through the intermediate bonding layer: the cover sheet is placed at a corresponding position on the substrate, and a tool is used to click the cover sheet to expel the air between the cover sheet and the substrate and tightly bond them; the process of expelling the air and tightly bonding is completed in one click; the clicking process is completed within 10 minutes after the surface activation treatment is completed; during the clicking process, the pressure applied to the surface of the cover sheet is less than or equal to 3N. The tool can be, for example, tweezers or other hard objects that are easy to apply force.

[0029] The air is discharged and tightly combined in one click, which can avoid the upper and lower misalignment of the substrate and the cover sheet caused by multiple operations. If the operation is repeated multiple times, the time will be prolonged, which will increase the risk of difficulty in adjusting the bonding layer after solidification. One click can reduce this risk. The clicking process completes the bonding within 10 minutes after the surface activation treatment is completed. If it exceeds 10 minutes, the effect of the surface activation may fail, resulting in loose bonding. The surface activation effect can be guaranteed within 10 minutes after the surface activation treatment is completed, ensuring that the bonding is firm. In addition, the click pressure is less than 3N, which can also avoid the deviation caused by excessive pressure. If the applied pressure is too large, the structure may be deformed. At the same time, if the pressure is too large, the cover sheet may deform, causing friction between the cover plate and the substrate surface or bubbles to occur, affecting adhesion.

[0030] Furthermore, in some embodiments, in the step of forming a metal film layer on the surface of one side of the substrate, the formation process includes an evaporation process. According to the application requirements of the chip, metal films of different materials can be selected for evaporation, and the metal films are connected to external devices to provide corresponding light, heat, and electric fields during the detection process, which are conducted to the microchannels of the cover sheet through the silicon dioxide layer to provide conditions for detection. The metal film layer needs to have a certain adhesion to the substrate material, and the thickness of the metal film layer is 10nm~100nm. If it is less than 10nm, the film layer is too thin, it is difficult to produce sufficient light and electricity effects, the photothermal effect is poor, and the generated electric field is too small; if it is higher than 100nm, the film layer is too thick, and it is difficult for light to pass through. At the same time, the electric field generated is too strong, which is not conducive to the detection effect.

[0031] Furthermore, in some embodiments, the method for manufacturing a microfluidic chip further includes: before the step of forming a metal film layer on one side surface of the substrate, pre-cleaning the substrate; the pre-cleaning process includes water washing, organic solvent washing or ultrasonic washing. Pre-cleaning provides cleanliness guarantee for the evaporation of the metal film layer. The cleanliness and flatness of the substrate surface will affect the adhesion, cleanliness and flatness of the metal film layer, and then affect the bonding stability. The pre-cleaned substrate can facilitate the adhesion of the metal film layer, improve the flatness of the film layer, and thus make the bonding stability high.

[0032] Furthermore, in some embodiments, the manufacturing method of the microfluidic chip also includes: buckling the cover sheet to the intermediate bonding layer, and after bonding to the substrate through the intermediate bonding layer, heat-baking the bonded cover sheet and the substrate to solidify the intermediate bonding layer; in the heat-baking step, the temperature is a constant temperature of 60°C to 70°C, for example, it can be 60°C, 65°C, 70°C (referring to any value in the range for constant temperature heat baking, rather than fluctuating within the range), and the heat-baking time is 10min to 60min, for example, it can be 10min, 20min, 30min, 40min, 50min, 60min. The intermediate bonding layer of silica can be further solidified by heat baking, and the bonding strength can be further enhanced. The heat-baking step can be performed in a constant temperature box, for example. If the time is too short or the temperature is too low, the bonding may be insufficient and the connection may not be firm.

[0033] The microfluidic chip manufactured by the above-mentioned microfluidic chip manufacturing method has a structure reference Figure 2 and Figure 3 ,include: A substrate 1, on which a metal film layer 11 is disposed; A cover sheet 2, wherein the cover sheet 2 is provided with at least a microchannel 21; An intermediate bonding layer 3, located between the substrate 1 and the cover sheet 2, and covering the metal film layer 11; Wherein, the cover sheet 2 is a PDMS prepolymer cover sheet; and the intermediate bonding layer 3 is a silicon dioxide layer.

[0034] A specific embodiment of the actual situation reference Figure 3 . 1 in the figure is the substrate 1 that is covered during coating and exposed after coating, and the material is glass. 11 in the figure is the metal film layer 11 on the surface of the substrate 1, which is a chromium film. 2 in the figure is a transparent cover sheet 2, which is a PDMS prepolymer cover sheet. Since the chromium film of the metal film layer 11 appears dark, the transparent cover sheet 2 also appears dark. Therefore, since the intermediate bonding layer 3 is a silicon dioxide layer, which is a transparent layer itself and has a relatively thin thickness, it is difficult to visually distinguish in the figure, and it actually covers the entire surface of the metal film layer 11. In addition, there is a light-colored transparent part under the cover sheet 2 in the figure. This part is the mirror image of the transparent cover sheet 2 on the intermediate bonding layer 3 / metal film layer 11, and it is not a solid structure.

[0035] Furthermore, the metal film layer 11 should at least cover the position corresponding to the microchannel 21. In some embodiments, the metal film layer 11 completely covers one side surface of the substrate 1; the intermediate bonding layer 3 completely covers the metal film layer 11. The metal film layer 11 that completely covers the surface can be beneficial to provide sufficient light, heat, and electrical effects. At the same time, it can adapt to any microchannel situation on the cover sheet. In addition, in different embodiments, the metal film layer 11 may not be set on the entire surface, or the area of ​​the metal film layer 11 may be smaller than the area of ​​the intermediate bonding layer 3, and the intermediate bonding layer completely covers the metal film layer 11 and extends out of the range of the metal film layer to be directly connected to the substrate. Those skilled in the art can make adjustments according to actual needs. The fully covered intermediate bonding layer 3 can ensure the bonding strength at any point on the surface, and the intermediate bonding layer 3 can also be graphed as needed.

[0036] Further, in some embodiments, the material of the substrate 1 includes silicon, glass, paper or PDMS prepolymer; the metal film layer 11 includes chromium, titanium, nickel or aluminum; the thickness of the metal film layer 11 is 10nm~100nm, for example, it can be 10nm, 20nm, 50nm, 80nm, 100nm; the thickness of the intermediate bonding layer 3 is 10nm~40nm, for example, it can be 10nm, 20nm, 30nm, 40nm. The metal film layer 11 is selected according to the material, and different thicknesses have different light absorption, reflection and transmittance, as well as different electrical and thermal response degrees. The thickness is determined according to the functions required for actual detection. If the thickness of the intermediate bonding layer 3 is too thin, it will affect the bonding effect, making the connection unstable, and it may be difficult to isolate some adverse effects of the metal film layer 11 below on the detection flow channel. If it is too thick, it may be excessively blocked, making it difficult for the light, heat and electricity effects of the metal film layer 11 to meet the design expectations, and it will also have an adverse effect on the detection effect.

[0037] The present invention has been described above by way of embodiments. It is believed that those skilled in the art can understand the present invention through the above embodiments. Obviously, the above embodiments are merely examples for the purpose of clear description, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A method for manufacturing a microfluidic chip, It is characterized in that The following steps are involved: providing a substrate; forming a metal film layer on one surface of the substrate; Providing a cover sheet, wherein the cover sheet is provided with at least a microfluidic channel; forming an intermediate bonding layer on the substrate, covering a surface of the substrate on which the metal film layer is formed; Performing surface activation treatment on the intermediate bonding layer; The cover sheet is buckled onto the intermediate bonding layer, and bonded to the substrate via the intermediate bonding layer; Wherein, the cover sheet is a PDMS prepolymer cover sheet; and the intermediate bonding layer is a silicon dioxide layer.

2. The method for manufacturing the microfluidic chip according to claim 1, It is characterized in that In the step of forming an intermediate bonding layer on the surface of the substrate having the metal film layer, a silicon dioxide layer is formed on the surface of the substrate having the metal film layer by magnetron sputtering as the intermediate bonding layer; The metal film layer covers the entire surface of the substrate thereunder, and the silicon dioxide layer covers the entire surface of the metal film layer.

3. The method for manufacturing the microfluidic chip according to claim 1, It is characterized in that In the step of forming an intermediate bonding layer on the surface of the substrate having the metal film layer, a silicon dioxide layer is formed on the surface of the substrate having the metal film layer by magnetron sputtering as the intermediate bonding layer; The area of ​​the metal film layer is smaller than that of the intermediate bonding layer. The intermediate bonding layer completely covers the metal film layer and extends beyond the range of the metal film layer to be directly connected to the substrate.

4. The method for manufacturing the microfluidic chip according to claim 1, It is characterized in that In the step of surface activation treatment, the intermediate bonding layer is bombarded with plasma; During the plasma bombardment process, the gas used is air or oxygen; the bombardment time is 20s~120s, the power is 50W~200W, and the gas flow rate is 100μl / min.

5. The method for manufacturing the microfluidic chip according to claim 1, It is characterized in that In the step of buckling the cover sheet to the intermediate bonding layer and bonding the cover sheet to the substrate via the intermediate bonding layer: The cover sheet is placed at a corresponding position on the base, and a tool is used to click the cover sheet to expel the air between the cover sheet and the base and tightly bond them.

6. The method for manufacturing the microfluidic chip according to claim 5, It is characterized in that The process of air discharge and tight bonding is completed in one click; the clicking process is completed within 10 minutes after the surface activation treatment is completed; During the clicking process, the pressure applied to the surface of the cover sheet is less than or equal to 3N.

7. The method for manufacturing a microfluidic chip according to claim 1, It is characterized in that In the step of forming a metal film layer on one side surface of the substrate, the forming process includes an evaporation process.

8. The method for manufacturing the microfluidic chip according to claim 1, It is characterized in that Also includes: Before the step of forming a metal film layer on one side surface of the substrate, pre-cleaning the substrate; The pre-cleaning process includes water cleaning, organic solvent cleaning or ultrasonic cleaning.

9. The method for manufacturing a microfluidic chip according to claim 1, It is characterized in that Also includes: The cover sheet is buckled onto the intermediate bonding layer, and after being bonded to the substrate via the intermediate bonding layer, the bonded cover sheet and the substrate are heat-baked to solidify the intermediate bonding layer.

10. The method for manufacturing the microfluidic chip according to claim 9, It is characterized in that In the heat-drying step, the temperature is kept constant at 60° C. to 70° C., and the heat-drying time is 10 min to 60 min.

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