Microfluidic chips, their fabrication methods and applications

Abstract

This invention relates to the field of microfluidic chip technology, and discloses a microfluidic chip, its fabrication method, and its application. The microfluidic chip includes a sample inlet (3), a mixing chamber (4), and a mixing inlet channel (10) with its two ends connected to the sample inlet (3) and the mixing chamber (4), respectively. The mixing inlet channel (10) is used to deliver liquid into the mixing chamber (4). The liquid inlet of the mixing inlet channel (10) is located on the upper part of the side wall of the sample inlet (3), and the liquid outlet of the mixing inlet channel (10) is located on the lower part of the side wall of the mixing chamber (4). The angle between the line connecting the liquid inlet and the liquid outlet of the mixing inlet channel (10) and the horizontal direction is greater than 30°. The microfluidic chip of this invention improves mixing efficiency and does not require external vacuum or pneumatic equipment.

Description

Technical Field

[0001] This invention relates to the field of microfluidic chip technology, specifically to a microfluidic chip, its fabrication method, and its applications. Background Technology

[0002] In recent years, the quality of water resources in my country has been declining, and the water environment has continued to deteriorate. To strengthen the supervision and control of water pollution, it is essential to conduct necessary testing on various pollutants in water to accurately determine the specific composition of the water body, enabling targeted treatment measures and regulatory methods. Developing simple, rapid, and real-time on-site detection technologies and methods for water pollution is imperative.

[0003] In the research of real-time water quality monitoring, microfluidic chip technology plays a crucial role. Due to their small size, microfluidic chips reduce reagent consumption, lower analysis costs, improve analytical efficiency, and reduce environmental pollution. They can be integrated into fully functional portable instruments for easy field use, and mass production further reduces costs, making them particularly suitable for emergency post-accident monitoring needs. Throughout the entire detection process, the design and structure of the microfluidic chip determine key factors such as efficiency and accuracy in water quality monitoring, making it the most critical part of the entire process. When using microfluidic chips to detect water quality, it is often necessary to achieve mixing of liquids (the water sample to be tested) and solids (detection reagents). This requires ensuring good mixing efficiency and reaction effects while preventing unreacted solid reagents from entering the subsequent detection cell and affecting the final detection results. Therefore, the design and arrangement of the mixing region within the microfluidic chip are of great significance.

[0004] Currently, CN106268472B employs an inverted V-shaped multi-stage mixing array structure for a passive micromixer, incorporating vortex, flow splitting and merging, and cross-shaped mixing structures. This micromixer significantly improves the mixing efficiency of microfluidics within the channel. CN108801959A discloses a microfluidic chip comprising a glass chip body with internal chip channels. These channels include an inlet section, a mixing section, and an outlet section connected sequentially along the fluid transport direction, with a wave-shaped tube within the mixing section. CN209215363U discloses a glass chip body with internal chip channels, including an inlet section, a mixing section, and an outlet section connected sequentially along the fluid transport direction. The inlet section is provided with a first interface and a second interface; the mixing section is provided with a third interface; and the outlet section's interface is connected to an ammonia nitrogen monitoring device. Microfluidic chips generally incorporate array structures and wave structures, and are mostly used for mixing liquids. Further research is needed on mixing solids and liquids.

[0005] Microfluidic chip technology is widely used in portable or real-time water quality testing. The key to detection lies in the mixing and reaction efficiency of the substances to be detected in the water with the corresponding reagents, which depends on the design of the chip channel structure. Current chips design wave, array, and other structures on the horizontal plane. These structures usually require external vacuum or pneumatic equipment to achieve mixing. Summary of the Invention

[0006] The purpose of this invention is to overcome the solid-liquid mixing problem in existing microfluidic chips, and to provide a microfluidic chip, its preparation method and application. This microfluidic chip has the effect of improving mixing efficiency and does not require external vacuum or pneumatic equipment.

[0007] To achieve the above objectives, the present invention provides a microfluidic chip comprising a sample inlet, a mixing chamber, and a mixing and injection channel connected at both ends to the sample inlet and the mixing chamber, respectively. The mixing and injection channel is used to deliver liquid into the mixing chamber. The liquid inlet of the mixing and injection channel is located on the upper part of the side wall of the sample inlet, and the liquid outlet of the mixing and injection channel is located on the lower part of the side wall of the mixing chamber. The angle between the line connecting the liquid inlet and the liquid outlet of the mixing and injection channel and the horizontal direction is 30° or more.

[0008] Preferably, the angle between the line connecting the liquid inlet and liquid outlet of the mixing injection channel and the horizontal direction is 40° to 70°, and more preferably 40° to 60°.

[0009] Preferably, the cross-section of the mixing injection channel is triangular, rectangular, hexagonal, or circular.

[0010] Preferably, the mixing injection channel is configured as a straight line or a curve in the direction of liquid flow.

[0011] Preferably, the cross-sectional area of ​​the mixing injection channel is 2-5 mm. 2 The length is 2-20 mm; preferably, the cross-sectional area of ​​the mixing injection channel is 3-5 mm². 2 The length is 5-20mm.

[0012] Preferably, the sample injection cell and / or the mixing cell are cubic, cuboid, cylindrical or hexahedral in shape, and have a volume of 20-100 μL.

[0013] Preferably, the microfluidic chip is made of one or more of the following materials: polymer, metal, silicon nitride, glass, silicon wafer, and metal, and the polymer is made of one or more of PMMA, PC, PVC, and PET.

[0014] Preferably, the microfluidic chip has a thickness of 5-15 mm and a shape of square, round, or hexagonal.

[0015] Preferably, the liquid inlet of the mixing injection channel is located at the top of the side wall of the injection cell, and the liquid outlet of the mixing injection channel is located at the bottom of the side wall of the mixing cell.

[0016] Preferably, the mixing tank contains a pre-prepared reagent.

[0017] Preferably, the amount of pre-placed reagent in the mixing tank is 1 / 2 to 4 / 5 of the mixing tank volume.

[0018] Preferably, the microfluidic chip includes a substrate, a cover plate, and a substrate sealed and clamped by the substrate and the cover plate; the sample injection cell, the mixing cell, and the mixing injection channel are formed on the substrate.

[0019] Preferably, the microfluidic chip further includes one or more of the following: a liquid inlet, a channel, a detection cell, and an air outlet.

[0020] A second aspect of the present invention provides a method for fabricating the microfluidic chip of the present invention described above, the method comprising: forming a sample inlet cell, a mixing cell, and a mixing sample inlet channel having both ends connected to the sample inlet cell and the mixing cell respectively on a substrate.

[0021] Preferably, the method further includes the steps of: after encapsulating the lower surface of the substrate with a film, pre-preparing a pre-prepared reagent in a mixing pool, and then encapsulating the upper surface of the substrate with a cover plate.

[0022] The third aspect of this invention provides the application of the microfluidic chip of the present invention or the microfluidic chip obtained by the preparation method of the present invention in water quality detection.

[0023] Through the above technical solution, this invention designs the chip horizontally as a liquid inlet, mixing tank, and detection tank; vertically, it controls the liquid to enter the mixing tank from the bottom and flow out from the top, fully mixing and reacting with the pre-placed reagent under the influence of gravity. This design not only improves the utilization rate of the microchannels on the chip but also effectively improves the mixing and reaction efficiency of the liquid and pre-placed reagent, thereby enhancing the detection effect. Furthermore, the chip's channel structure design is simple, its fabrication difficulty and cost are low, facilitating further promotion and application.

[0024] By using the microfluidic chip of this invention for water quality detection, the space utilization of the chip can be improved, the mixing and reaction efficiency of liquids and solids can be effectively improved, and the application and promotion of microfluidic chips in detecting parameters such as COD, ammonia nitrogen, nitric acid, nitrite, phosphoric acid, and heavy metal ions in water quality can be facilitated. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view of the microfluidic chip according to the first embodiment of the present invention;

[0026] Figure 2 This is a top view of the microfluidic chip according to the first embodiment of the present invention;

[0027] Figure 3 This is a cross-sectional view of the substrate of a microfluidic chip according to another embodiment of the present invention;

[0028] Figure 4 This is a cross-sectional view of the substrate of a microfluidic chip according to another embodiment of the present invention;

[0029] Figure 5 This is a cross-sectional view of the substrate of a microfluidic chip according to another embodiment of the present invention;

[0030] Figure 6 It is a cross-sectional view of the substrate for comparing microfluidic chips;

[0031] Figure 7 This is a cross-sectional view of the substrate of another microfluidic chip for comparison.

[0032] Explanation of reference numerals in the attached figures

[0033] 1. Liquid inlet hole; 2. Channel; 3. Liquid inlet tank

[0034] 4. Mixing tank; 5. Detection tank; 6. Air outlet.

[0035] 7. Film negative 8. Cover slip 9. Pre-prepared reagents

[0036] 10. Mixed sample inlet channel

[0037] α, Inlet channel angle Detailed Implementation

[0038] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0039] In this invention, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to the corresponding directions in the accompanying drawings, and the cross-sections all refer to cross-sections perpendicular to the direction of liquid flow.

[0040] This invention provides a microfluidic chip, such as Figure 1-2As shown, the microfluidic chip includes a sample inlet 3, a mixing chamber 4, and a mixing sample inlet channel 10 with both ends connected to the sample inlet 3 and the mixing chamber 4 respectively. The mixing sample inlet channel 10 is used to deliver liquid into the mixing chamber 4.

[0041] The liquid inlet of the mixing injection channel 10 is located on the upper part of the side wall of the injection cell 3, and the liquid outlet of the mixing injection channel 10 is located on the lower part of the side wall of the mixing cell 4.

[0042] The angle between the line connecting the liquid inlet and the liquid outlet of the mixing injection channel 10 and the horizontal direction is 30° or more.

[0043] In this invention, the "upper part of the side wall" refers to the portion within 40% downward from the top of the side wall, preferably the top of the side wall; the "lower part of the side wall" refers to the portion within 40% upward from the bottom of the side wall, preferably the bottom of the side wall.

[0044] According to the present invention, by providing a downwardly inclined mixing injection channel 10 as described above, the test liquid from the injection cell 3 can be better mixed in the mixing cell 4 under its own gravity, thereby improving the mixing efficiency.

[0045] According to the present invention, preferably, the angle between the line connecting the liquid inlet and the liquid outlet of the mixing injection channel 10 and the horizontal direction is 40° to 70°, more preferably 40° to 60°. In the present invention, the angle between the line connecting the liquid inlet and the liquid outlet of the mixing injection channel 10 and the horizontal direction is also referred to as the injection channel angle, denoted by α.

[0046] According to the present invention, the cross-sectional shape of the mixing injection channel 10 is not particularly limited, and can be, for example, a triangle, a rectangle, a hexagon or a circle, preferably a circle or a square.

[0047] According to the present invention, the mixing injection channel 10 is configured as a straight line or a curve in the liquid flow direction. Preferably, from the perspective of facilitating the formation of the mixing injection channel 10, it is a straight line, i.e., the interior of the mixing injection channel 10 is configured as a column.

[0048] According to the present invention, the cross-sectional area of ​​the mixing injection channel 10 can be 2-5 mm. 2 The length is 2-20 mm; preferably, the cross-sectional area of ​​the mixing injection channel 10 is 3-5 mm². 2 The length is 5-20mm; for example, the cross-sectional area can be 45mm². 2 The length is 5mm.

[0049] According to the present invention, the sample injection cell 3 and / or the mixing cell 4 are cubic, cuboid, cylindrical or hexahedral in shape, and have a volume of 20-100 μL.

[0050] According to the present invention, the microfluidic chip can be made of one or more of polymer materials, metals, silicon nitride, glass, silicon wafers, and metals. The polymer material can be, for example, one or more of PMMA, PC, PVC, and PET. Preferably, the thickness of the microfluidic chip is 5-15 mm, and its shape can be square, circular, or hexagonal.

[0051] To achieve better mixing, preferably, the liquid inlet of the mixing inlet channel 10 is located at the top of the side wall of the sample inlet cell 3, and the liquid outlet of the mixing inlet channel 10 is located at the bottom of the side wall of the mixing cell 4. The above-mentioned positions can be adjusted to match the required inlet channel angle α by adjusting the distance between the sample inlet cell 3 and the mixing cell 4.

[0052] According to a preferred embodiment of the present invention, a pre-prepared reagent 9 is pre-placed in the mixing cell 4. In this case, the improved mixing efficiency of the present invention refers to promoting the mixing between the test liquid from the sample injection cell 3 and the pre-prepared reagent 9 in the mixing cell 4. The pre-prepared reagent 9 can be a reagent pre-placed according to the chip's application, and can be a solid reagent or a packaged liquid reagent, etc. By pre-preparing the pre-prepared reagent 9 in the mixing cell 4, detection using a microfluidic chip can be performed conveniently and quickly, and the detection accuracy can be improved without the need for external equipment.

[0053] According to the present invention, the loading amount of the pre-placed reagent 9 in the mixing cell 4 is 1 / 2 to 4 / 5 of the volume of the mixing cell 4, preferably 2 / 3. According to a preferred embodiment of the present invention, the volume of the injection cell 3 and / or the mixing cell 4 is 35 μL, and the loading amount of the pre-placed reagent 9 in the mixing cell 4 is 2 / 3 of the volume of the mixing cell 4.

[0054] According to the present invention, in order to suit the application of the chip, chip structures such as liquid inlet 1, channel 2, detection pool 5 and vent 6 can also be provided on the chip. The setting position and size of the above chip structures can be appropriately adjusted as needed.

[0055] According to the present invention, in order to facilitate the formation of the sample inlet 3, the mixing chamber 4, and the mixing sample inlet channel 10, the microfluidic chip preferably includes a substrate 7, a cover plate 8, and a substrate sealed and clamped by the substrate 7 and the cover plate 8; the sample inlet 3, the mixing chamber 4, and the mixing sample inlet channel 10 are formed on the substrate. By utilizing a microfluidic chip with such a structure, the various structures on the chip can be formed more conveniently.

[0056] To fabricate the aforementioned microfluidic chip, adhesive can be applied to one side of the cover plate 8, allowing it to be directly attached to the substrate. Pressing the cover plate firmly will bond the two together, forming the microfluidic chip. The cover plate 8 is preferably a transparent, rigid polymer material (e.g., PMMA, PC, PET). The cover plate 8 and the substrate 7 can be made of the same or different materials.

[0057] According to a specific embodiment of the present invention, the liquid inlet tank 3, the mixing tank 4, and the detection tank 5 are preferably configured to penetrate the substrate, and their shapes can be cubic, cuboid, cylindrical, hexahedral, etc., with a volume of, for example, 20-100 μL.

[0058] According to a specific embodiment of the present invention, channel 2 is preferably formed as a cylinder (e.g., a round cylinder or a square cylinder), with a base area of ​​2-5 mm². 2 The length can be 5mm or more.

[0059] According to a specific embodiment of the present invention, the liquid inlet 1 and the air outlet 6 can be configured as cubes, cuboids, cylinders, hexahedrons, etc.

[0060] According to the present invention, the substrate of the microfluidic chip can be made of any rigid material, preferably a transparent rigid material, such as transparent rigid polymer materials such as PMMA, PC, and PET. Furthermore, the substrate 7 and cover plate 8 are preferably made of transparent rigid materials, such as transparent rigid polymer materials such as PMMA, PC, and PET. The materials of the substrate, substrate 7, and cover plate 8 can be the same or different.

[0061] As a method of bonding the film 7, cover plate 8 and substrate, adhesive can be applied to one side of the film 7 and cover plate 8 and the three are then bonded together.

[0062] A second aspect of the present invention provides a method for fabricating the microfluidic chip of the present invention described above, the method comprising: forming a sample injection cell 3, a mixing cell 4, and a mixing sample injection channel 10 with both ends connected to the sample injection cell 3 and the mixing cell 4 respectively on a substrate.

[0063] Preferably, the method further includes the steps of: after encapsulating the lower surface of the substrate with a film 7, pre-positioning a pre-prepared reagent 9 in a mixing tank 4, and encapsulating the upper surface of the substrate with a cover plate 8.

[0064] by Figure 1 Taking the microfluidic chip shown as an example, its fabrication method may include the following steps:

[0065] S1) A liquid inlet hole 1, a sample inlet cell 3, a mixing cell 4, a detection cell 5, a mixing sample inlet channel 10 with both ends connected to the sample inlet cell 3 and the mixing cell 4 respectively, and a channel 2 with both ends connected to the liquid inlet hole 1 and the sample inlet cell 3 respectively, a channel 2 with both ends connected to the mixing cell 4 and the detection cell 5 respectively, and a channel 2 with both ends connected to the detection cell 5 and the gas outlet hole 6 respectively are formed on the substrate.

[0066] S2) The bottom surface of the substrate is encapsulated with film 7, and the pre-prepared reagent 9 is pre-prepared in the mixing cell 4;

[0067] S3) An vent hole 6 and a liquid inlet hole 1 are formed on the cover plate, and the upper surface of the substrate is encapsulated with the cover plate 8.

[0068] The flow channels 2, with their two ends connected to the liquid inlet 1 and the sample inlet 3 respectively, are formed on the lower surface of the substrate. Flow channels 2, with their two ends connected to the mixing tank 4 and the detection tank 5 respectively, and flow channels 2, with their two ends connected to the detection tank 5 and the vent 6 respectively, are formed on the upper surface of the substrate. All of the above flow channels 2 are formed by slotting the surface of the substrate. The liquid inlet 1, the sample inlet 3, the mixing tank 4, and the detection tank 5 are all cylindrical holes that penetrate the substrate.

[0069] When using the microfluidic chip of the present invention for detection, the liquid to be tested can be injected into the chip using tools such as a pipette. The liquid to be tested flows inside the chip and mixes with the pre-prepared reagent 9 in the mixing cell 4 before entering the detection cell 5 to complete the detection.

[0070] The third aspect of this invention provides the application of the microfluidic chip of the present invention or the microfluidic chip obtained by the preparation method of the present invention in water quality detection.

[0071] To enable the detection of specific parameters in water using a microfluidic chip, the substances in the water need to be thoroughly mixed and reacted with the detection reagent for further detection. In the chip fabrication process, a chip structure including an inlet cell, mixing cell, detection cell, and channels is first constructed on a substrate. Then, a substrate film is encapsulated on the lower surface of the substrate. Next, the detection reagent is filled into the mixing cell, and finally, a cover film is encapsulated on the upper surface to form a closed detection channel. The chip adjusts the setting and position of the mixing inlet channel 10 between the inlet cell and the mixing cell to change the mixing efficiency between the test liquid and the pre-placed reagent. By controlling the setting and position of the mixing inlet channel 10, the test liquid enters from the bottom of the mixing cell and slowly accumulates inside, causing the water level to rise. During this process, the test liquid simultaneously mixes and reacts with the pre-placed reagent in the mixing cell. When the mixing cell is full, it flows out from the top into the detection cell. This not only fully utilizes the vertical space of the channels on the chip but also enhances the contact time with the pre-placed reagent under the influence of gravity, improving mixing efficiency.

[0072] Specific detection parameters can be set as needed, such as COD, ammonia nitrogen, nitric acid, nitrite, phosphoric acid, heavy metal ions, etc.

[0073] The present invention will be described in detail below through embodiments.

[0074] In the following examples and comparative examples, Figures 3-7 The microstructure of each chip in the substrate and Figure 1 The substrate is formed accordingly, and the relevant reference numerals are omitted.

[0075] In the following examples and comparative examples, ammonia nitrogen content in water samples was analyzed using a microfluidic chip. The ammonia nitrogen composition analysis standard (GBW(E)080220 100 mg / L) was purchased from the China Standard Material Network and diluted 20 times as the test liquid. The solid ammonia nitrogen detection reagent was WAK-ammonia nitrogen from Kyoritsu Rika Water Quality Test Kit, purchased from Japan, and pre-filled into the mixing tank. The mixing efficiency was examined by testing the change in absorbance of the liquid flowing into the detection tank after mixing. Spectrophotometry was used for testing, with a deuterium / tungsten lamp light source from Ocean Optics and a QE Pro spectrometer, with a detection wavelength of 640 nm.

[0076] Example 1

[0077] Preparation cross-sectional diagram as shown Figure 1 Top view as follows Figure 2 The microfluidic chip shown is made of polymethyl methacrylate (PMMA), with a thickness of 10 mm and a rectangular shape (20 cm * 5 cm). The rigid substrate includes an inlet hole 1, an inlet pool 3, a mixing and injection channel 10, a mixing pool 4, a detection pool 5, an outlet hole 6, and multiple channels 2. The inlet pool 3, mixing pool 4, and detection pool 5 are all through-holes on the substrate, cylindrical in shape, with a volume of 35 μL. Channel 2 is a cylinder with a base area of ​​4 mm². 2 The length is 5mm or more. The mixing injection channel 10 is a cylinder with a base area of ​​4mm². 2 The liquid inlet is located at the top of the side wall of the liquid inlet tank 3, and the liquid outlet is located at the bottom of the side wall of the mixing tank 4. The angle α between the line connecting the liquid inlet and the liquid outlet and the horizontal direction is 45°. The liquid inlet 1 and the air outlet 6 have a bottom area of ​​6 mm². 2 The cylindrical shape. The substrate 7 and cover plate 8 are both polycarbonate (PC) sheets, which are directly glued to both sides of the rigid substrate to form a sealed liquid inlet 3, a mixing and sample inlet channel 10, a mixing pool 4, a detection pool 5, and multiple channels 2.

[0078] Mixing tank 4 is pre-filled with ammonia nitrogen detection reagent, filling it to half its capacity. For example... Figure 1As shown, the liquid to be tested is injected into the chip using a pipette. The liquid from the inlet cell 3 enters from the bottom of the mixing cell 4 through the inclined mixing injection channel 10. The liquid slowly accumulates from bottom to top in the mixing cell 4, and after filling the entire mixing cell 4, it flows into the detection cell 5 from the top.

[0079] During the liquid delivery process, the liquid and the pre-prepared reagent were fully mixed and reacted, and the absorbance in the detection cell was finally measured to be 1.267.

[0080] Example 2

[0081] The microfluidic chip was prepared according to the method in Example 1, the only difference being that the structure of the rigid substrate was as follows. Figure 3 As shown, the liquid inlet of the mixing sample inlet channel 10 is located at the top of the side wall of the liquid inlet pool 3, and the liquid outlet is located at about 1 / 3 of the way up from the bottom of the side wall of the mixing pool 4. The angle α between the line connecting the liquid inlet and the liquid outlet and the horizontal direction is 35°.

[0082] The ammonia nitrogen content was detected in the same manner as in Example 1, and the absorbance in the detection cell was finally measured to be 1.035. The absorbance is lower than that in Example 1, indicating a decrease in mixing efficiency.

[0083] Example 3

[0084] The microfluidic chip was prepared according to the method in Example 1, the only difference being that the structure of the rigid substrate was as follows. Figure 4 As shown, the liquid inlet of the mixing sample inlet channel 10 is located at the top of the side wall of the liquid inlet tank 3, and the liquid outlet is located at the bottom of the side wall of the mixing tank 4. By adjusting the distance between the liquid inlet tank 3 and the mixing tank 4, the angle α between the line connecting the liquid inlet and the liquid outlet and the horizontal direction is 60°.

[0085] The ammonia nitrogen content was detected in the same manner as in Example 1, and the absorbance in the detection cell was finally measured to be 1.258. The absorbance was similar to that in Example 1, and the mixing efficiency was basically the same. However, the α angle in this chip was too large, and the slope of the mixing inlet channel 10 was large, which increased the difficulty of chip fabrication.

[0086] Example 4

[0087] The microfluidic chip was prepared according to the method in Example 1, the only difference being that the structure of the rigid substrate was as follows. Figure 5 As shown, the liquid inlet of the mixing sample inlet channel 10 is located at the upper end of the side wall of the liquid inlet tank 3, and the liquid outlet is located at the upper end of the side wall of the mixing tank 4. By adjusting the distance between the liquid inlet tank 3 and the mixing tank 4, the angle α between the line connecting the liquid inlet and the liquid outlet and the horizontal direction is 30°.

[0088] The ammonia nitrogen content was detected in the same manner as in Example 1, and the absorbance in the detection cell was finally measured to be 1.271. The absorbance was similar to that in Example 1, and the mixing efficiency was basically the same. However, the α angle in this chip was too small, and the mixing inlet channel 10 was too long, resulting in an excessively large chip volume and high consumption of raw materials for chip preparation.

[0089] Comparative Example 1

[0090] The microfluidic chip was prepared according to the method in Example 1, the only difference being that the structure of the rigid substrate was as follows. Figure 6 As shown, the mixing injection channel 10 is set horizontally, the liquid inlet is set at the lower end of the side wall of the liquid inlet pool 3, and the liquid outlet is set at the lower end of the side wall of the mixing pool 4. The angle α between the line connecting the liquid inlet and the liquid outlet and the horizontal direction is 0°.

[0091] The ammonia nitrogen content was detected in the same manner as in Example 1, and the absorbance in the detection cell was measured to be 1.204. The absorbance is slightly lower than that in Example 1, indicating that its mixing efficiency is slightly worse than that in Example 1. However, this structure is prone to liquid backflow.

[0092] Comparative Example 2

[0093] The microfluidic chip was prepared according to the method in Example 1, the only difference being that the structure of the rigid substrate was as follows. Figure 7 As shown, the mixing injection channel 10 is set horizontally, the liquid inlet is set at the upper end of the side wall of the liquid inlet pool 3, and the liquid outlet is set at the upper end of the side wall of the mixing pool 4. The angle α between the line connecting the liquid inlet and the liquid outlet and the horizontal direction is 0°.

[0094] The ammonia nitrogen content was detected in the same manner as in Example 1, and the absorbance in the detection cell was finally measured to be 1.147. The absorbance was lower than that in Example 1, indicating that the mixing efficiency was reduced.

[0095] Comparative Example 3

[0096] Without using a microfluidic chip, the reagent and liquid were mixed directly, and the absorbance was measured to be 0.856. Compared with mixing on a microfluidic chip, the absorbance was lower, indicating reduced mixing efficiency.

[0097] By comparing the results of the above embodiments and comparative examples, it can be seen that the microfluidic chip of the present invention has a significantly better effect on improving the solid-liquid mixing efficiency.

[0098] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A microfluidic chip, characterized in that, The microfluidic chip includes a sample inlet (3), a mixing chamber (4), and a mixing inlet channel (10) with its two ends connected to the sample inlet (3) and the mixing chamber (4) respectively. The mixing inlet channel (10) is used to deliver liquid into the mixing chamber (4). The liquid inlet of the mixing injection channel (10) is located on the upper part of the side wall of the injection pool (3), and the liquid outlet of the mixing injection channel (10) is located on the lower part of the side wall of the mixing pool (4). The angle between the line connecting the liquid inlet and the liquid outlet of the mixing injection channel (10) and the horizontal direction is more than 30°. The amount of pre-placed reagent (9) in the mixing tank (4) is 1 / 2 to 4 / 5 of the volume of the mixing tank (4).

2. The microfluidic chip according to claim 1, wherein, The angle between the line connecting the liquid inlet and the liquid outlet of the mixing injection channel (10) and the horizontal direction is 40° to 70°.

3. The microfluidic chip according to claim 2, wherein, The angle between the line connecting the liquid inlet and the liquid outlet of the mixing injection channel (10) and the horizontal direction is 40° to 60°.

4. The microfluidic chip according to claim 1, wherein, The cross-section of the mixing injection channel (10) is triangular, rectangular, hexagonal or circular; And / or, the mixing inlet channel (10) is configured to be straight or curved in the direction of liquid flow.

5. The microfluidic chip according to claim 4, wherein, The mixing injection channel (10) is set to be straight in the direction of liquid flow.

6. The microfluidic chip according to claim 1, wherein, The cross-sectional area of ​​the mixing injection channel (10) is 2-5 mm. 2 The length is 2-20mm.

7. The microfluidic chip according to claim 6, wherein, The cross-sectional area of ​​the mixing injection channel (10) is 3-5 mm. 2 The length is 5-20mm.

8. The microfluidic chip according to claim 1, wherein, The sample injection cell (3) and / or the mixing cell (4) are cubic, cuboid, cylindrical or hexahedral in shape, and have a volume of 20-100 μL.

9. The microfluidic chip according to claim 1, wherein, The microfluidic chip is made of one or more of the following materials: polymer, metal, silicon nitride, glass, and silicon wafer. The polymer material is one or more of PMMA, PC, PVC, and PET.

10. The microfluidic chip according to claim 1, wherein, The microfluidic chip has a thickness of 5-15mm and is square, round, or hexagonal in shape.

11. The microfluidic chip according to any one of claims 1-10, wherein, The liquid inlet of the mixing injection channel (10) is located at the top of the side wall of the injection pool (3), and the liquid outlet of the mixing injection channel (10) is located at the bottom of the side wall of the mixing pool (4).

12. The microfluidic chip according to any one of claims 1-10, wherein, The microfluidic chip includes a substrate (7), a cover plate (8), and a base plate sealed and clamped by the substrate (7) and the cover plate (8); the sample injection cell (3), the mixing cell (4), and the mixing injection channel (10) are formed on the base plate.

13. The microfluidic chip according to claim 12, wherein, The microfluidic chip also includes one or more of the following: liquid inlet (1), channel (2), detection cell (5), and air outlet (6).

14. A method for fabricating a microfluidic chip according to any one of claims 1-13, characterized in that, The method includes the steps of forming a sample injection cell (3), a mixing cell (4), and a mixing injection channel (10) with its two ends connected to the sample injection cell (3) and the mixing cell (4) respectively on a substrate.

15. The preparation method according to claim 14, wherein, The method further includes the steps of: after encapsulating the lower surface of the substrate with a film (7), pre-preparing a pre-prepared reagent (9) in a mixing pool (4), and encapsulating the upper surface of the substrate with a cover plate (8).

16. The application of the microfluidic chip according to any one of claims 1-13 or the microfluidic chip obtained by the preparation method according to claim 14 or 15 in water quality detection.

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