A microfluidic chip containing a superhydrophobic structure and a preparation method thereof

Abstract

The present invention provides a microfluidic chip containing a superhydrophobic structure, which belongs to the field of microfluidic chip technology. The superhydrophobic structure is arranged in the hydrophobic area to realize the superhydrophobic function. The superhydrophobic structure is prepared on the insulating layer above the droplet drive electrode array, and is a surface micron array or nano array with a specific shape. The present invention also provides a method for preparing a microfluidic chip containing a superhydrophobic structure, which adopts photolithography technology to transfer the micron array or nano array pattern of a specific shape to the insulating layer. The microfluidic chip containing a superhydrophobic structure and the preparation method thereof of the present invention avoid the method of using imported fluorine-containing hydrophobic materials in the prior art, can fully realize localization, and is no longer affected by international trade factors. At the same time, it also saves procurement and process costs, is of great significance, and has wider applicability.

Description

Technical Field

[0001] The invention belongs to the technical field of microfluidic chips and relates to a microfluidic chip containing a super-hydrophobic structure and a preparation method thereof. Background Art

[0002] Microfluidics is a scientific technology that precisely controls and manipulates microscale fluids, primarily at the micro- and nanoscale. It has the ability to miniaturize basic laboratory functions in biology and chemistry, such as sample preparation, reaction, separation, and detection, onto a chip a few square centimeters. Its fundamental characteristic and greatest advantage lies in the flexible combination and large-scale integration of multiple unit technologies on a microscopic, controllable platform. It is an interdisciplinary field encompassing engineering, physics, chemistry, microfabrication, and bioengineering. To ensure the smooth and continuous movement of microfluidics on a chip, the chip surface must be superhydrophobic, and achieving this surface quality has become a key technology in this field.

[0003] In the existing technology, a layer of fluorine-containing hydrophobic material is usually coated on the surface of the chip, for example, Cytop (a non-crystalline, highly transparent fluorine-containing polymer, Cytop is the trade name, the corresponding material name is perfluoro (1-butenyl vinylether) polymer). However, this fluorine-containing hydrophobic material is imported and has not yet been domestically produced. It is subject to export controls by the country of origin, resulting in high procurement costs. In addition, the process of preparing the super-hydrophobic film is complex, and the labor and time costs are high.

[0004] Therefore, there is an urgent need to study a pioneering method to integrate the preparation process of superhydrophobic structures into the wafer production process of microfluidic chips, so as to reduce production costs and improve efficiency, while also achieving full localization and no longer being affected by international trade factors. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a microfluidic chip containing a superhydrophobic structure and a preparation method thereof, the insulating layer is rationally designed and processed, and a surface micron array or nanoarray with a specific shape is prepared on its surface, so that it can realize the insulation function while also realizing the superhydrophobic function.

[0006] To achieve the above object, the present invention provides a microfluidic chip containing a super-hydrophobic structure, wherein the chip range is divided into a droplet-driven effective area and an ineffective area, wherein the hydrophobic area includes the entire range of the droplet-driven effective area and a portion of the ineffective area, and the other portion of the ineffective area is the peripheral area of ​​the chip;

[0007] A droplet driving electrode array is provided in the droplet driving effective area for driving the flow of droplets, and a superhydrophobic structure is provided in the hydrophobic area to realize the superhydrophobic function. The superhydrophobic structure is prepared on the insulating layer above the droplet driving electrode array and is a surface micron array or nano array with a specific shape, realizing both insulation and superhydrophobic functions.

[0008] Furthermore, the super-hydrophobic structure is a micro-pillar array on the surface of the insulating layer, or a micro-pore array on the surface of the insulating layer, or a honeycomb array on the surface of the insulating layer, or a grid array on the surface of the insulating layer.

[0009] Furthermore, the depth of the surface micro-array or nano-array having a specific shape is smaller than the thickness of the insulating layer.

[0010] The present invention also provides a method for preparing the microfluidic chip containing the super-hydrophobic structure as described above, comprising the following steps:

[0011] A driving circuit, the droplet driving electrode array and an insulating layer are sequentially manufactured on a chip substrate;

[0012] Photolithography is used to transfer a micron array or nanometer array pattern of a specific shape onto the insulating layer.

[0013] Furthermore, the specific shape of the micron array or nanometer array pattern is transferred to the insulating layer using photolithography technology as follows:

[0014] coating a layer of photoresist on the insulating layer;

[0015] Using a mask with a micron array or nanometer array pattern of a specific shape to expose, develop, and clean the photoresist, the micron array or nanometer array pattern of the specific shape is transferred to the photoresist layer;

[0016] Etching the insulating layer to transfer a micron array or nano array pattern with a specific shape to the insulating layer;

[0017] Remove the photoresist layer, clean and dry.

[0018] Furthermore, the photoresist is a positive photoresist or a negative photoresist, and the pattern of the photoresist and the mask is matched so that the pattern of the photoresist layer retained after exposure and development is a micron array or nanometer array pattern with a specific shape.

[0019] Furthermore, the etching process adopts dry etching, and the etching depth is controlled by the etching rate and etching time, and the etching depth is controlled to be smaller than the thickness of the insulating layer.

[0020] Furthermore, the photoresist layer is removed by wet method using a stripping solution.

[0021] Furthermore, when the super-hydrophobic structure is a micro-pillar array on the surface of the insulating layer, the diameter of the unit circle pattern on the mask is in the range of 1 to 5 μm, the distance between the unit circle patterns is equal to their diameter, and the range enclosed by the array pattern is equal to the range of the hydrophobic area.

[0022] The advantages of the present invention using the above technical solution are:

[0023] The microfluidic chip containing a superhydrophobic structure and the preparation method thereof of the present invention reasonably design and process the insulating layer, and prepare a surface micron array or nano array with a specific shape on the surface thereof, wherein the height of the micron array or nano array is less than the thickness of the insulating layer, that is, the side of the insulating layer close to the droplet driving electrode still retains a film layer of a certain thickness on the entire surface, so that it can realize the insulation function while also realizing the superhydrophobic function; the preparation process of the superhydrophobic structure is integrated into the wafer production process of the microfluidic chip, which not only reduces the cost but also improves the efficiency; avoids the method of using imported fluorine-containing hydrophobic materials in the prior art, can fully realize localization, is no longer affected by international trade factors, and also saves procurement and process costs, which is of great significance and has wider applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of the range division of the microfluidic chip containing a super-hydrophobic structure of the present invention;

[0026] Figure 2 Schematic diagram of a micropillar array on the surface of the insulating layer in the present invention;

[0027] Figure 3 Schematic diagram of the process flow of transferring a micrometer array or nanometer array pattern of a specific shape onto an insulating layer using photolithography technology in the present invention;

[0028] Figure 4 Schematic diagram of the mask structure used in preparing the micropillar array on the surface of the insulating layer in the present invention;

[0029] Explanation of the accompanying figures: 1-chip; 2-droplet driving effective area 2; 3-inactive area; 4-hydrophobic area; 11-chip substrate; 12-driving circuit; 21-the droplet driving electrode array; 22-insulating layer; 23-photoresist; 24-graphic photoresist layer. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention 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 making creative efforts are within the scope of protection of the present invention.

[0031] The present invention provides a microfluidic chip containing a super-hydrophobic structure, such as Figure 1 As shown, the chip 1 is divided into a droplet driving active area 2 and an inactive area 3, the hydrophobic area 4 includes the entire droplet driving active area 2 and a portion of the inactive area 3, and the other portion of the inactive area 3 is the peripheral area of ​​the chip 1;

[0032] A droplet driving electrode array 21 is provided in the droplet driving effective area 2 for driving the flow of droplets, and a super-hydrophobic structure is provided in the hydrophobic area 4 to realize the super-hydrophobic function. The super-hydrophobic structure is prepared on the insulating layer above the droplet driving electrode array 21, and is a surface micro-array or nano-array with a specific shape, realizing both insulation and super-hydrophobic functions.

[0033] The super-hydrophobic structure is a micro-pillar array on the surface of the insulating layer, or a micro-pore array on the surface of the insulating layer, or a honeycomb array on the surface of the insulating layer, or a grid array on the surface of the insulating layer. The research on the hydrophobic structures of lotus leaves, butterfly wings, water strider feet, etc. in nature is a bionic technology. In addition, it is also necessary to control the depth of the surface micro-array or nano-array with a specific shape to be less than the thickness of the insulating layer. In some embodiments, the super-hydrophobic structure is a micro-pillar array on the surface of the insulating layer, and its three-dimensional schematic diagram is as follows: Figure 2 shown.

[0034] The present invention also provides a method for preparing the microfluidic chip containing the super-hydrophobic structure as described above, comprising the following steps:

[0035] The driving circuit 12, the droplet driving electrode array 21 and the insulating layer 22 are sequentially manufactured on the chip substrate 11;

[0036] Photolithography is used to transfer a micron array or nanometer array pattern of a specific shape onto the insulating layer.

[0037] Furthermore, as shown in 3, the specific shape of the micron array or nano array pattern is transferred to the insulating layer using photolithography technology as follows:

[0038] Coating a layer of photoresist 23 on the insulating layer 22;

[0039] The photoresist 23 is exposed, developed, and cleaned using a mask having a micron array or nanometer array pattern of a specific shape, and the micron array or nanometer array pattern of the specific shape is transferred to the photoresist layer 24;

[0040] Etching the insulating layer 22 to transfer a micron array or nanometer array pattern having a specific shape to the insulating layer 22;

[0041] The photoresist layer 24 is removed, cleaned, and dried.

[0042] The photoresist 23 is a positive photoresist or a negative photoresist. The pattern of the photoresist 23 and the mask are matched so that the pattern photoresist layer 24 retained after exposure and development is a micron array or nanometer array pattern with a specific shape.

[0043] The etching process utilizes dry etching, controlling the etching depth by the etching rate and etching time. The etching depth is controlled to be less than the thickness of the insulating layer 22 to ensure that the insulating layer 22 is not etched through. The thickness of the insulating layer 22 is generally set to 0.5 to 1.5 μm. For example, a 1 μm etching depth is controlled to be 0.8 μm. While the etching depth may fluctuate positively or negatively in the actual process, it is ensured that the etching depth is less than the thickness of the insulating layer 22, i.e., the insulating layer 22 is not etched through. In some embodiments, a wet method is used to remove the photoresist layer using a stripping solution.

[0044] Wherein, when the super-hydrophobic structure is a micro-pillar array on the surface of the insulating layer, the pattern of the mask is as follows: Figure 4 As shown in the figure, the diameter D of the unit circle pattern on the mask ranges from 1 to 5 μm, the distance between the unit circle patterns is equal to their diameter D, the range enclosed by the array pattern is equal to the range of the hydrophobic area, and the position of the microcolumns on the surface of the insulating layer corresponds one-to-one to the position of the unit circle pattern on the mask. Due to the angle shadow caused by the exposure process, the prepared microcolumns are not absolutely cylindrical, but have a small taper on the side, as shown in the figure. Figure 2 shown.

[0045] The advantages of the present invention using the above technical solution are:

[0046] The microfluidic chip containing a superhydrophobic structure and the preparation method thereof of the present invention reasonably design and process the insulating layer, and prepare a surface micron array or nano array with a specific shape on the surface thereof, wherein the height of the micron array or nano array is less than the thickness of the insulating layer, that is, the side of the insulating layer close to the droplet driving electrode still retains a film layer of a certain thickness on the entire surface, so that it can realize the insulation function while also realizing the superhydrophobic function; the preparation process of the superhydrophobic structure is integrated into the wafer production process of the microfluidic chip, which not only reduces the cost but also improves the efficiency; avoids the method of using imported fluorine-containing hydrophobic materials in the prior art, can fully realize localization, is no longer affected by international trade factors, and also saves procurement and process costs, which is of great significance and has wider applicability.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a microfluidic chip containing a superhydrophobic structure, wherein the microfluidic chip is divided into a droplet-driven active area and an inactive area, wherein the hydrophobic area includes the entire droplet-driven active area and a portion of the inactive area, and the other portion of the inactive area is the peripheral area of ​​the chip; A droplet driving electrode array is provided in the droplet driving effective area for driving the droplet flow, and a super-hydrophobic structure is provided in the hydrophobic area to achieve a super-hydrophobic function. The super-hydrophobic structure is prepared on an insulating layer above the droplet driving electrode array and is a surface micron array or nano array with a specific shape, achieving both insulation and super-hydrophobic functions. The method is characterized in that it comprises the following steps: A driving circuit, the droplet driving electrode array and an insulating layer are sequentially manufactured on a chip substrate; Photolithography is used to transfer a micron array or nanometer array pattern of a specific shape onto the insulating layer.

2. The preparation method according to claim 1, characterized in that The super-hydrophobic structure is a micro-column array on the surface of the insulating layer, or a micro-pore array on the surface of the insulating layer, or a honeycomb array on the surface of the insulating layer, or a grid array on the surface of the insulating layer.

3. The preparation method according to claim 1, characterized in that The depth of the surface micro-array or nano-array having a specific shape is smaller than the thickness of the insulating layer.

4. The preparation method according to claim 1, characterized in that The specific shape of the micron array or nano array pattern is transferred to the insulating layer using photolithography technology. coating a layer of photoresist on the insulating layer; Using a mask with a micron array or nanometer array pattern of a specific shape to expose, develop, and clean the photoresist, the micron array or nanometer array pattern of the specific shape is transferred to the photoresist layer; Etching the insulating layer to transfer a micron array or nano array pattern with a specific shape to the insulating layer; Remove the photoresist layer, clean and dry.

5. The preparation method according to claim 4, characterized in that The photoresist is a positive photoresist or a negative photoresist. The pattern of the photoresist and the mask is matched so that the pattern of the photoresist layer retained after exposure and development is a micron array or nanometer array pattern with a specific shape.

6. The preparation method according to claim 4, characterized in that The etching process adopts dry etching, and the etching depth is controlled by the etching rate and etching time, and the etching depth is controlled to be smaller than the thickness of the insulating layer.

7. The preparation method according to claim 4, characterized in that The photoresist layer is removed by wet method using a stripping solution.

8. The preparation method according to claim 4, characterized in that When the super-hydrophobic structure is a micro-pillar array on the surface of the insulating layer, the diameter of the unit circle pattern on the mask is in the range of 1 to 5 μm, the distance between the unit circle patterns is equal to their diameter, and the range enclosed by the array pattern is equal to the range of the hydrophobic area.

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