Micro-fluidic chip capable of realizing classical two-step method

Abstract

The micro-fluidic chip capable of realizing the classical two-step method comprises a biological chip and a structural chip pressed on the biological chip, the biological chip and the structural chip are enclosed to form a micro-channel, the left end of the micro-channel is communicated with a buffer solution injection hole formed in the structural chip, and the right end of the micro-channel is communicated with a buffer solution injection hole formed in the structural chip. The microchannel is sequentially provided with a marking area, a detection area and a reference area from left to right, the structural chip is further provided with a flow guide hole, the flow guide hole is formed between the marking area and the detection area, a magnetic control stop valve is arranged in the flow guide hole, the bottom of the magnetic control stop valve is inserted into the flow guide hole and makes contact with the upper surface of the biological chip, and the bottom of the magnetic control stop valve is in contact with the upper surface of the biological chip. An iron material which can be adsorbed by the magnet is arranged at the top of the magnetic control stop valve, the bottom of the magnetic control stop valve is separated from the flow guide hole after the magnetic control stop valve is adsorbed by magnetic force, and a water absorption material is arranged at the bottom of the magnetic control stop valve. By utilizing the chip, the change of the acting force of liquid flow in the micro-channel can be effectively avoided, and the detection sensitivity is improved.

Description

Technical Field

[0001] This invention belongs to the field of in vitro diagnostics and immunoassay technology, and specifically relates to a microfluidic chip that can realize the classic two-step method. Background Technology

[0002] Microfluidics, as a novel point-of-care testing (POCT) method, boasts advantages such as miniaturization, integration, and high throughput, demonstrating its unique strengths across multiple fields. With technological advancements and reduced manufacturing costs, this technology holds immense promise for applications, particularly in rapid diagnostics, personalized medicine, and environmental monitoring. Currently, the most mature product application is the unidirectional lateral flow immunomicrofluidic chip, which typically utilizes surface hydrophilic / hydrophobic properties or capillary forces to drive fluid movement within microchannels, while simultaneously incorporating immunological principles to detect specific antigens or antibodies in the sample.

[0003] However, unidirectional flow microfluidic chips have the following problems: 1. They cannot achieve indirect mode. In conventional unidirectional lateral flow microfluidics, the detection zone is coated with capture antigen, and the labeled secondary antibody is placed in the labeling zone. After the sample is added, the antibodies to be detected in the sample (including specific and non-specific antibodies) first bind to the labeled secondary antibody, and then bind to the capture antigen coated in the detection zone, forming a complex of capture antigen-specific antibody-labeled secondary antibody. In this mode, non-specific antibodies in the sample will interfere and neutralize the labeled secondary antibody, and the analytical sensitivity cannot meet clinical needs. 2. Detection of protein antigens is prone to the hook effect. In conventional unidirectional lateral flow microfluidics, the detection zone is coated with capture antibody, and the labeled antibody is placed in the labeling zone. After the sample is added, the antigen to be tested binds sequentially with the labeled antibody (liquid phase) and the capture antibody (solid phase) to form a double antibody sandwich complex. However, the antigen to be tested and the labeled antibody preferentially bind in the liquid phase. Subsequently, the antigen to be tested-labeled antibody complex is captured by the capture antibody to form a double antibody sandwich complex. In this case, there is a significant difference in the rate of the two binding reactions. Especially when the content of the antigen to be tested in the sample is too high, the antigen to be tested and the labeled antibody bind excessively and cannot be captured by the capture antibody when it moves to the detection area, thus producing a false negative result (HOOK effect). 3. The analytical sensitivity for detecting small molecule antigens needs improvement. In conventional unidirectional lateral flow microfluidic systems, two detection modes are typically used. The first mode involves coating the labeled antigen in the labeling zone and the antibody in the detection zone. After sample addition, the sample reconstitutes the labeled antigen in the labeling zone and moves to the detection zone. Both the antigen to be tested and the labeled antigen compete for binding with the solid-phase antibody. However, in this mode, the analytical sensitivity often fails to meet clinical needs. The second mode involves coating the labeled antibody in the labeling zone and the competing antigen in the detection zone. After sample addition, the antigen to be tested preferentially encounters the labeled antibody and preferentially binds to a limited amount of the labeled antibody. The remaining antibody continues to move forward and binds to the coated antibody in the detection zone to form a complex. In this mode, the labeled antibody and the antigen to be tested collide and bind in the liquid phase, while the labeled antibody and the competing antibody bind on the solid-phase surface. The reaction rates of the two differ, and the coating of the antigen on the solid-phase surface may affect its activity, thereby reducing its binding ability with the labeled antibody, resulting in analytical sensitivity that fails to meet clinical needs.

[0004] CN221926380U proposes a bidirectional microfluidic chip, characterized by a flow channel filled with an absorbent material within the biochip. A movable waste collection area is positioned on the lower surface of the biochip at the outer end of the flow channel. This design allows the sample to first contact the detection area in reverse to capture the antigen / antibody, followed by a secondary flow to dissolve the labeled substance. This design achieves the classic two-step method, effectively addressing problems that unidirectional lateral flow microfluidic chips cannot solve. However, this design of the flow guide hole brings the following problems: First, the flow guide hole and the waste liquid collection area connected to it are located on the bottom side of the microchannel. After absorbing liquid, the water-absorbing material in the flow guide hole and the waste liquid collection area expand, causing the chip to tilt and the force on the liquid flow in the microchannel to change, thus affecting the stability of the results. Second, with the flow guide hole located on the bottom side of the microchannel, some fluorescent microspheres will fall into the flow guide hole due to gravity when flowing through it. Third, in the second step of sample addition, the water-absorbing material and waste liquid collection area filled in the flow guide hole need to be removed, and this removal device needs to be located on the bottom side of the chip, which makes the manufacturing process difficult. Utility Model Content

[0005] This invention addresses the shortcomings of existing bidirectional dual-drive microfluidic chips by proposing a microfluidic chip that can realize the classic two-step method. This chip can effectively avoid changes in the liquid flow force within the microchannel, prevent losses caused by the fall of fluorescent microspheres, and improve detection sensitivity.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows: A microfluidic chip capable of implementing the classic two-step method includes a biochip and a structural chip pressed onto the biochip. The biochip and the structural chip enclose a microchannel. The left end of the microchannel communicates with a buffer injection port on the structural chip. A flow control valve is provided at the right end of the microchannel, controlling the opening and closing of the flow path of liquid in the microchannel. The microchannel is provided with a labeling area, a detection area, and a reference area from left to right. The structural chip is also provided with a sample injection port and a flow guide port. The sample injection port is located between the reference area and the flow control valve. The flow guide port is located between the labeling area and the detection area. A magnetically controlled interceptor valve is provided inside the flow guide port. The bottom of the magnetically controlled interceptor valve is inserted into the flow guide port and contacts the upper surface of the biochip. The top of the magnetically controlled interceptor valve is provided with an iron material that can be attracted by a magnet. After being attracted by magnetism, the bottom of the magnetically controlled interceptor valve detaches from the flow guide port. A water-absorbing material is provided at the bottom of the magnetically controlled interceptor valve.

[0007] The magnetically controlled interceptor valve includes a head and a body. The head is connected to the body at the bottom. The outer periphery of the head is circular or rectangular. The outer periphery of the body is circular. The diameter or width of the head is greater than the diameter of the guide hole. The diameter of the body is smaller than the diameter of the guide hole. The diameter of the body is smaller than the width of the microchannel.

[0008] The head includes an iron outer shell and a water-absorbing inner core. The outer shell wraps around the inner core, and the bottom of the inner core is connected to the body. The body is made of water-absorbing material.

[0009] The lower surface of the structural chip has a groove along its length, and the structural chip forms a microchannel by enclosing the upper surface of the biochip through the groove.

[0010] The height of the microchannel is 20-50 μm, and the width of the microchannel is 2-3 mm.

[0011] The diameter of the body is 1.0 mm to 2.0 mm, and the diameter of the head or the length of its wide side is greater than 3 mm.

[0012] The diameter of the guide hole is 1.5 mm-2.5 mm, and the distance between the guide hole and the marking area is half the distance between the guide hole and the detection area.

[0013] The flow control valve is made of a movable absorbent material, which moves to contact or move away from the microchannel.

[0014] The microfluidic chip that achieves the classic two-step method obtained through the above technical solution has the following advantages:

[0015] 1. Effectively avoid changes in the force of fluid flow within the microchannel: A flow guide hole is set in the biochip, and a magnetically controlled intercept valve is built into the flow guide hole. This device is located in the structure chip. After the intercept valve absorbs the liquid, it will not cause the chip to tilt, nor will it cause changes in the force of fluid flow in the microchannel, thus ensuring stable results.

[0016] 2. Effectively avoids loss of fluorescent microspheres and improves detection sensitivity: Since the flow channel is located in the structure chip, based on the laminar flow theory in microchannels, the fluorescent microspheres dried on the surface of the biochip will move forward along the biochip after rehydration, without contacting the structure chip. This effectively avoids the problem of fluorescent microspheres getting stuck in the flow channel of the structure chip and improves detection sensitivity.

[0017] 3. Easy to process and manufacture: A magnetically controlled intercept valve is built into the flow guide hole of the structure chip. After the liquid flow in the microchannel is completely absorbed by the intercept valve, the iron shell of the head is attracted by an external electromagnet, and the valve body is pulled out as a whole by applying a plumb force, and the channel is restored to unobstructed. This removal mechanism is simple and the chip is easy to produce. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the microfluidic chip (perspective) that can realize the classic two-step method according to this utility model;

[0019] Figure 2 This is a schematic diagram of the structure of the biochip described in this utility model;

[0020] Figure 3 This is a schematic diagram of the structure of the magnetically controlled interceptor valve described in this utility model;

[0021] Figure 4 This is a cross-sectional view of the microfluidic chip that can realize the classic two-step method according to this utility model;

[0022] Figure 5 This is a schematic diagram of the structure of the magnetically controlled interceptor valve described in this utility model during use;

[0023] Figure 6 This is a schematic diagram illustrating the principle of adding liquid to the sample injection hole using the microfluidic chip described in this invention;

[0024] Figure 7 This is a schematic diagram of the microfluidic chip of this invention adding liquid through a buffer injection hole.

[0025] In the figure, 1 is the biochip; 2 is the structural chip; 3 is the microchannel; 4 is the buffer injection port; 5 is the flow control valve; 6 is the sample injection port; 7 is the flow guide port; 8 is the magnetically controlled intercept valve; 31 is the labeling area; 32 is the detection area; 33 is the reference area; 81 is the head; 81a is the outer shell; 81b is the inner core; and 82 is the body. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0027] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this utility model pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0028] This utility model relates to the field of immunoassay technology, specifically to a microfluidic chip that enables the classic two-step method for microfluidic detection. While achieving the classic two-step method for microfluidic detection, it can effectively avoid changes in the fluid flow force within the microchannel, prevent losses caused by the fall of fluorescent microspheres, and improve the sensitivity of the detection.

[0029] The present invention will be further explained below with reference to the embodiments and accompanying drawings. It should be understood that the present invention is not limited to the specific embodiments described.

[0030] like Figure 1-2 , Figure 4-5 As shown, this utility model proposes a microfluidic chip that can realize the classic two-step method, including a biochip 1 and a structural chip 2 pressed onto the biochip. The biochip 1 and the structural chip 2 enclose a microchannel 3. The left end of the microchannel 3 is connected to a buffer injection hole 4 opened on the structural chip 2. A flow control valve 5 is provided at the right end of the microchannel 3. The flow control valve 5 controls the opening and closing of the flow path of liquid in the microchannel 3 to the flow control valve 5. From left to right, the microchannel 3 is provided with a marking area 31, a detection area 32, and a reference area 33. The structural chip 2... The device is also provided with a sample injection hole 6 and a flow guide hole 7. The sample injection hole 6 is located between the reference area 33 and the liquid flow control valve 5. The flow guide hole 7 is located between the marking area 31 and the detection area 32. A magnetically controlled intercept valve 8 is provided inside the flow guide hole 7. The bottom of the magnetically controlled intercept valve 8 is inserted into the flow guide hole 7 and contacts the upper surface of the biochip 1. The top of the magnetically controlled intercept valve 8 is provided with an iron material that can be attracted by a magnet. After being attracted by magnetic force, the bottom of the magnetically controlled intercept valve 8 is detached from the flow guide hole 7. The bottom of the magnetically controlled intercept valve 8 is provided with a water-absorbing material.

[0031] like Figure 5 As shown, the interception and removal mechanism of the magnetically controlled intercept valve 8 is as follows: when the liquid flow in the microchannel 3 contacts the bottom of the magnetically controlled intercept valve 8, the liquid flow immediately enters the magnetically controlled intercept valve 8 because the suction force it provides is greater than the capillary force in the microchannel; after the liquid flow in the microchannel 3 is completely absorbed by the intercept valve, the top iron material is attracted by the external electromagnet, and the valve body is pulled out as a whole by applying the plumb pull force, and the channel is restored to unobstructed flow, ensuring that the subsequent reagent flow and reaction are not disturbed.

[0032] like Figure 6-7 As shown, the working process of a microfluidic chip is illustrated below:

[0033] A. Detection of Detectable Molecules: Move the flow control valve 5 to the far right, disconnecting it from the microchannel 3. After adding the sample to be tested into the sample injection port 6, the sample flows to the left and right. Since the microchannel 3 is not connected to the flow control valve 5, the liquid flowing to the right remains at the end of the microchannel 3 due to surface tension and will not flow out spontaneously, while the liquid flowing to the left continues to flow. When it reaches the detection zone, the analyte binds to the solidified antigen / antibody in the detection zone 32. The liquid continues to flow and is intercepted at the magnetically controlled intercept valve 8. Because the suction force provided by the magnetically controlled intercept valve 8 is greater than the capillary force in the microchannel, the liquid is immediately collected into the magnetically controlled intercept valve 8 and will not continue to flow to the left. After all the liquid in the microchannel 3 has been collected into the magnetically controlled intercept valve 8, activate the electromagnet inside the instrument. The electromagnet acts on the iron material at the top of the magnetically controlled intercept valve 8, applying a vertical pulling force to pull the entire magnetically controlled intercept valve 8 out, restoring the microchannel 3 to its unobstructed state and ensuring that subsequent reagent flow and reactions are not disturbed.

[0034] B. Label binding stage: Move the flow control valve 5 to the far left, embedding it into the microchannel 3. Add buffer solution to the buffer injection hole 4. Under the action of capillary driving force, the buffer solution enters the microchannel 3 and dissolves the labeled substance in the labeled area 31 as it flows through it. After the labeled substance reaches the detection area 32 with the liquid flow, it is captured by the corresponding substance in the detection area 32. The remaining liquid flow is collected into the flow control valve 5.

[0035] like Figure 3 As shown, the magnetically controlled interceptor valve 8 includes a head 81 and a body 82. The head 81 is connected to the body 82 at the bottom. The outer periphery of the head 81 is circular or rectangular, and the outer periphery of the body 82 is circular. The diameter or width of the head 81 is greater than the diameter of the guide hole 7, so that the head 81 of the magnetically controlled interceptor valve is stuck outside the guide hole 7. The diameter of the body 82 is smaller than the diameter of the guide hole 7. Since the water-absorbing material of the body 82 will expand after contact with water, its diameter is required to be slightly smaller than the diameter of the guide hole 7, so that the body 82 can enter and exit the guide hole 7 before and after expansion. The diameter of the body 82 is smaller than the width of the microchannel 3. Since the water-absorbing material of the body 82 will expand after contact with water, its diameter is required to be slightly smaller than the width of the microchannel 3, so that after absorbing water and expanding, it will fill the entire microchannel 3 and intercept the liquid flow.

[0036] The head 81 includes an iron outer shell 81a and a water-absorbing inner core 81b. The outer shell 81a wraps around the inner core 81b, and the bottom of the inner core 81b is connected to the body 82, which is made of water-absorbing material.

[0037] Preferably, the body 82 of the magnetically controlled intercept valve 8 is composed of a porous hydrophilic polymer. The porous hydrophilic polymer is made by mixing water-absorbing materials such as polymer hydrogels, cellulose-based materials, sponges, etc., with reinforcing fillers such as nanocellulose fibers and silica nanoparticles. The mixing ratio of the two materials is 10:1. The water-absorbing materials can provide strong water absorption, and the reinforcing fillers are used to increase the hardness of the materials and maintain the appearance of the body 82.

[0038] The lower surface of the structural chip 2 has a groove along its length, and the structural chip 2 forms a microchannel 3 by means of the groove and the upper surface of the biochip 1.

[0039] The height of the microchannel 3 is 20-50 μm, and the width of the microchannel 3 is 2-3 mm.

[0040] The diameter of the body 82 is 1.0 mm to 2.0 mm, and the diameter of the head 81 or the length of its wide side is greater than 3 mm.

[0041] The diameter of the guide hole 7 is 1.5 mm-2.5 mm, and the distance between the guide hole 7 and the marking area 31 is half the distance between the guide hole 7 and the detection area 32.

[0042] The flow control valve 5 is made of a movable absorbent material, which moves to contact or move away from the microchannel 3.

[0043] Example: Detection of Mycoplasma pneumoniae (MP) IgM antibodies

[0044] 1. Fabrication of a magnetically controlled interceptor valve

[0045] The magnetically controlled interceptor valve consists of a head and a body. The body is made of a porous hydrophilic polymer, which is manufactured by mixing absorbent materials such as polymeric hydrogels, cellulose-based materials, and sponges with reinforcing fillers such as nanofibers and silica nanoparticles. The mixing ratio of the two materials is 10:1. The absorbent materials provide strong water absorption, while the reinforcing fillers increase the material's hardness and maintain the body's appearance. The body is cylindrical, with a diameter of 1.0 mm-2.0 mm and a height of 2-4 mm. The head of the magnetically controlled interceptor valve is cylindrical or rectangular, with a diameter >3 mm. It consists of a core made of a porous hydrophilic polymer and an outer iron shell.

[0046] (1) Fabrication of the magnetically controlled interceptor valve body: First, weigh hydrogel powder (purchased from Xi'an Qiyue Biotechnology Co., Ltd.) and silica particles (purchased from Fengrun Chemical Co., Ltd.) at a mass ratio of 10:1, and grind them thoroughly in a grinder to ensure that the filler is dispersed and does not agglomerate. Second, dissolve the mixture in ultrapure water and sonicate it. Third, fill the mixture into a mold and heat it at 60°C for crosslinking. Finally, immerse the molded body in 0.1 mol / L NaOH solution for 30 min to enhance its surface hydrophilicity, and dry it in an oven at 60°C.

[0047] (2) Fabrication of the magnetic interception valve head: Using the same porous polymer formula as the body, press it into a cylinder or rectangular block with a diameter of 3.5 mm, embed it into the iron shell, and leave the bottom and the contact surface of the body uncovered by iron to ensure the water absorption is connected.

[0048] (3) Connection between the head and body of the magnetically controlled interceptor valve: Apply polyester polyurethane adhesive (purchased from Jiangsu Water Elf Environmental Protection New Materials Co., Ltd.) to the upper end of the body and bond the head without the iron shell covering it to it. Pressurize and maintain for 5 min, then cure at room temperature for 24 h.

[0049] 2. Fabrication of structural chips

[0050] The structured chip is made of PMMA material. The microchannel structure, flow channel, sample injection port, buffer injection port and other structures in the chip are designed using CAD software, and then the PMMA surface is processed using a CO2 laser etching machine.

[0051] 3. Fabrication of biochips

[0052] First, activated avidin was spotted in the detection and reference areas of the biochip, incubated, the film was washed, and dried. Then, biotinylated MP recombinant antigen and biotinylated goat anti-mouse IgG polyclonal antibody were spotted in the detection and reference areas respectively. After incubation, the film was washed again, and then mouse anti-human IgM antibody labeled with fluorescent microspheres was spotted in the labeling area. The film was dried at 37°C. The biochip preparation was then completed.

[0053] 4. Microfluidic chip assembly procedure

[0054] First, a magnetically controlled interceptor valve is embedded in the flow channel of the structured chip; second, a flow control valve is placed in the waste liquid chamber of the structured chip. Then, the structured chip is bonded to the biochip, thus completing the fabrication of the microfluidic chip.

[0055] 5. Testing Procedure

[0056] First, move the flow control valve to the far right, disconnecting it from the microchannel. Add 10 μL of the sample to be tested into the sample injection port. The sample flows to the left and right. Because the microchannel is not connected to the flow control valve, the liquid flowing to the right remains at the end of the microchannel due to the surface tension at the tip and will not flow out spontaneously, while the liquid flowing to the left continues to flow. When it reaches the detection zone, the MP-specific IgM antibody in the sample is captured by the anti-human IgM antibody in the detection zone. The liquid continues to flow and is intercepted at the magnetically controlled intercept valve. Because the suction force provided by the magnetically controlled intercept valve is greater than the capillary force in the microchannel, the liquid is immediately collected into the magnetically controlled intercept valve and will not continue to flow to the left. Second, after all the liquid in the microchannel has been collected into the magnetically controlled intercept valve, activate the electromagnet inside the instrument. The electromagnet acts on the iron shell of the magnetically controlled intercept valve head, applying a vertical pulling force to pull the entire magnetically controlled intercept valve out, restoring the microchannel to its open state and ensuring that subsequent reagent flow and reactions are not disturbed. Next, move the flow control valve to its leftmost position, embedding it within the microchannel. Add buffer solution through the buffer injection well. Driven by the capillary force, the solution enters the microchannel and flows through the labeled area, dissolving the fluorescent microspheres coupled with the MP recombinant antigen. Once the labeled material reaches the detection area, the captured specific IgM antibody binds to it. The remaining liquid is collected in the flow control valve. Finally, use the analyzer to routinely read the fluorescence signal values ​​(T and R) of the detection and reference areas.

[0057] 6. Experimental Results

[0058] Table 1 Comparison of detection results for the two types of chips

[0059]

[0060] As shown in Table 1, when testing the same sample, the detection results of the novel microfluidic chip are significantly higher than those of the bidirectional microfluidic chip (CN221926380U). This is because the flow guide holes of the bidirectional microfluidic chip proposed in CN221926380U are located on the bottom side of the microchannel. When the fluorescent microspheres flow through the flow guide holes, some of them become trapped in them due to gravity. However, the microfluidic chip proposed in this invention has its flow guide holes located on the top side of the microchannel, which effectively avoids the problem of fluorescent microspheres becoming trapped in the flow guide holes.

[0061] Table 2. Detection repeatability of the two chips

[0062]

[0063] As shown in Table 2, the repeatability of the microfluidic chips proposed in this invention is within an acceptable range (CV < 15%). However, the reproducibility of the bidirectional microfluidic chip (CN221926380U) is poor. This is because the flow guide hole of the bidirectional microfluidic chip proposed in CN221926380U is located on the bottom side of the microchannel. The water-absorbing material and waste liquid collection area in the flow guide hole expand after absorbing liquid, causing the chip to tilt. This changes the force on the liquid flow in the microchannel, thus affecting the stability of the results.

[0064] The above technical solution only embodies the preferred technical solution of this utility model. Any changes that may be made by those skilled in the art to certain parts of it embody the principle of this utility model and fall within the protection scope of this utility model.

[0065] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0066] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0067] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

Claims

1. A microfluidic chip capable of implementing a classic two-step method, comprising a biochip (1) and a structural chip (2) pressed onto the biochip, wherein the biochip (1) and the structural chip (2) enclose a microchannel (3), the left end of the microchannel (3) is connected to a buffer injection hole (4) opened on the structural chip (2), and a flow control valve (5) is provided at the right end of the microchannel (3), wherein the flow control valve (5) controls the opening and closing of the flow path of liquid in the microchannel (3) to the flow control valve (5), and the microchannel (3) is provided with a marking area (31), a detection area (32), and a reference area (33) from left to right, characterized in that, The structure chip (2) is also provided with a sample injection hole (6) and a flow guide hole (7). The sample injection hole (6) is located between the reference area (33) and the liquid flow control valve (5). The flow guide hole (7) is located between the marking area (31) and the detection area (32). A magnetically controlled intercept valve (8) is provided in the flow guide hole (7). The bottom of the magnetically controlled intercept valve (8) is inserted into the flow guide hole (7) and contacts the upper surface of the biochip (1). The top of the magnetically controlled intercept valve (8) is provided with an iron material that can be attracted by a magnet. After the magnetically controlled intercept valve (8) is attracted by magnetic force, the bottom of the magnetically controlled intercept valve (8) is separated from the flow guide hole (7). The bottom of the magnetically controlled intercept valve (8) is provided with a water-absorbing material.

2. A microfluidic chip capable of implementing the classic two-step method according to claim 1, characterized in that, The magnetically controlled intercept valve (8) includes a head (81) and a body (82). The head (81) is connected to the body (82) at the bottom. The outer periphery of the head (81) is circular or rectangular, and the outer periphery of the body (82) is circular. The diameter or width of the head (81) is greater than the diameter of the guide hole (7), and the diameter of the body (82) is smaller than the diameter of the guide hole (7). The diameter of the body (82) is smaller than the width of the microchannel (3).

3. A microfluidic chip capable of implementing the classic two-step method according to claim 2, characterized in that, The head (81) includes an iron outer shell (81a) and a water-absorbing inner core (81b), the outer shell (81a) wrapping around the inner core (81b), the bottom of the inner core (81b) being connected to the body (82), the body (82) being made of water-absorbing material.

4. A microfluidic chip capable of implementing the classic two-step method according to claim 1, characterized in that, The lower surface of the structural chip (2) is provided with a groove along its length direction, and the structural chip (2) is surrounded by the upper surface of the biochip (1) through the groove to form a microchannel (3).

5. A microfluidic chip capable of implementing the classic two-step method according to claim 2, characterized in that, The height of the microchannel (3) is 20-50 μm and the width of the microchannel (3) is 2-3 mm.

6. A microfluidic chip capable of implementing the classic two-step method according to claim 5, characterized in that, The diameter of the body (82) is 1.0 mm to 2.0 mm, and the diameter of the head (81) or the length of its wide side is greater than 3 mm.

7. A microfluidic chip capable of implementing the classic two-step method according to claim 6, characterized in that, The diameter of the guide hole (7) is 1.5 mm-2.5 mm, and the distance between the guide hole (7) and the marking area (31) is half the distance between the guide hole (7) and the detection area (32).

8. A microfluidic chip capable of implementing the classic two-step method according to claim 1, characterized in that, The flow control valve (5) is a movable absorbent material, which moves to contact or move away from the microchannel (3).

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