Microfluidic device and microfluidic sensing system

Abstract

A microfluidic device and a microfluidic sensing system. The microfluidic device (100) comprises a microfluidic body (10) and a flow channel switching assembly (20). The microfluidic body (10) is provided with a first main flow channel (11), a second main flow channel (12), a first waste flow channel (13) and a second waste flow channel (14). The flow channel switching assembly (20) is rotatably connected to the microfluidic body (10). The flow channel switching assembly (20) is configured to rotate to a first position to connect the first main flow channel (11) and the second main flow channel (12). The flow channel switching assembly (20) is further configured to rotate to a second position to connect the first main flow channel (11), the second main flow channel (12) and the first waste flow channel (13). When the flow channel switching assembly (20) is in the second position, the second main flow channel (12) is isolated from the second waste flow channel (14).

Description

Microfluidic device and microfluidic sensing system Technical Field

[0001] The present application relates to microfluidic control, and in particular to a microfluidic device and a microfluidic sensing system. Background Art

[0002] Microfluidics, the technology for controlling, manipulating, and sensing complex fluids at microscopic scales, is a new interdisciplinary field developed based on microelectronics, micromechanics, bioengineering, and nanotechnology. In experiments in biology, chemistry, materials science, and other fields, fluid manipulation is often required. For example, sample DNA preparation, liquid chromatography, PCR reactions, and electrophoresis sensing are all performed in liquid environments. If sample preparation, biochemical reactions, and result sensing are integrated onto a biochip, the volume of fluid used in the experiment must be reduced from milliliters to microliters, necessitating the use of microfluidic devices. Microfluidic devices have a wide range of applications in biotechnology research due to their lightweight design, low sample or reagent requirements, fast reaction speed, massively parallel processing, and disposable design.

[0003] During the production of microfluidic devices, reagents need to be injected into the flow channels of the flow control detection device and introduced into the microcavity structure of the biochip to achieve pre-encapsulation of the reagents in the microcavity structure. However, after pre-encapsulation, the excess reagent needs to be discharged through the flow channels. Therefore, in related technologies, the flow channels that have flowed excess reagents also need to be cleaned, making the process more cumbersome. Moreover, if the cleaning is not done promptly, crystallization is likely to occur if the reagents remain for a long time, affecting subsequent user use.

[0004] Summary of the Invention

[0005] In view of this, it is necessary to provide a microfluidic device and a microfluidic sensing system.

[0006] In a first aspect, the present application provides a microfluidic device comprising a microfluidic body and a flow channel switching assembly. The microfluidic body is provided with a first main flow channel, a second main flow channel, a first waste liquid flow channel, and a second waste liquid flow channel. The flow channel switching assembly is rotatably connected to the microfluidic body. The flow channel switching assembly is used to rotate to a first position, thereby connecting the first main flow channel and the second main flow channel. The flow channel switching assembly is also used to rotate to a second position, thereby connecting the first main flow channel, the second main flow channel, and the first waste liquid flow channel. When the flow channel switching assembly is in the second position, the second main flow channel and the second waste liquid flow channel are isolated from each other.

[0007] A second aspect of the present application provides a microfluidic sensing system, comprising a sensing device and the microfluidic device described above, wherein the sensing device is configured to sense fluid within the microfluidic device and generate a corresponding signal.

[0008] In the present application, in the first mode and the second mode, the administrator can perform relevant pretreatment on the microfluidic device, and the waste liquid generated by the pretreatment operation can be discharged from the dedicated first waste liquid flow channel without contaminating the user's second waste liquid flow channel, thereby eliminating the step of cleaning the second waste liquid flow channel after the pretreatment operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG1 is a schematic diagram of the overall structure of a microfluidic sensing system provided in one embodiment of the present application.

[0010] FIG2 is an exploded view of the microfluidic sensing system shown in FIG1 .

[0011] FIG3 is a simplified diagram of the flow channel layout within the microfluidic device of the microfluidic sensing system shown in FIG2 .

[0012] FIG4 is a schematic diagram of flow channel connections when the microfluidic device shown in FIG3 is in a first mode.

[0013] FIG5 is a schematic diagram of flow channel connections when the microfluidic device shown in FIG3 is in the second mode.

[0014] FIG6 is a schematic diagram of flow channel connections when the microfluidic device shown in FIG3 is in the third mode.

[0015] FIG. 7 is a schematic diagram of flow channel connections when the microfluidic device shown in FIG. 3 is in the fourth mode.

[0016] FIG8 is an exploded view of the microfluidic device shown in FIG2 .

[0017] FIG9 is a schematic structural diagram of a microfluidic body of the microfluidic device shown in FIG8 .

[0018] FIG10 is a schematic structural diagram of the microfluidic body shown in FIG9 from another angle.

[0019] FIG11 is a cross-sectional view of the microfluidic device shown in FIG1 along the cutting line AA.

[0020] FIG12 is a top view of the microfluidic device shown in FIG8 in the first mode.

[0021] FIG13 is a top view of the microfluidic device shown in FIG8 in the second mode.

[0022] FIG14 is a top view of the microfluidic device shown in FIG8 in the third mode.

[0023] FIG15 is a top view of the microfluidic device shown in FIG8 in the fourth mode.

[0024] FIG16 is a schematic structural diagram of a flow channel switching assembly of the microfluidic device shown in FIG8 .

[0025] FIG17 is a top view of the microfluidic body shown in FIG8 .

[0026] FIG18 is a partial enlarged view of the first cover plate at position B shown in FIG17 .

[0027] FIG19 is a bottom view of the microfluidic body shown in FIG8 .

[0028] FIG. 20 is a schematic structural diagram of a sealing plug of a fluid storage component of the microfluidic device shown in FIG. 8 .

[0029] FIG21 is a schematic structural diagram of the sealing plug shown in FIG20 from another angle.

[0030] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present application in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0032] It should be noted that when a component is referred to as being "fixed to" or "mounted on" another component, it may be directly on the other component or there may be a central component. When a component is referred to as being "disposed on" another component, it may be directly on the other component or there may be a central component. As used herein, the term "and / or" includes all and any combinations of one or more of the relevant listed items.

[0033] 1 and 2 , one embodiment of the present application provides a microfluidic sensing system 1, comprising a microfluidic device 100 and a sensing device 200. The microfluidic device 100 and the sensing device 200 are stacked and interconnected in a first direction X, which is the thickness direction of the microfluidic device 100.

[0034] The microfluidic device 100 includes a microfluidic body 10 and a flow channel switching assembly 20. Referring also to FIG3 , the microfluidic body 10 is provided with multiple flow channels. These flow channels include a first main flow channel 11, a second main flow channel 12, a first waste liquid flow channel 13, a second waste liquid flow channel 14, and an air flow channel 15. This embodiment uses two main flow channels as an example, but it is understood that in other embodiments, the number of main flow channels may vary based on actual needs.

[0035] The channel switching assembly 20 is rotatably connected to the microfluidic body 10. The channel switching assembly 20 is provided with at least one liquid flow channel. During the rotation of the channel switching assembly 20 relative to the microfluidic body 10, the positions of the various liquid flow channels also change accordingly. When the channel switching assembly 20 is rotated to a specific position relative to the microfluidic body 10, the liquid flow channels can be connected to different channels, thereby switching the microfluidic device 100 to the corresponding mode. Please refer to Figures 4 to 7. In some embodiments, the channel switching assembly 20 is provided with a first liquid flow channel 21, a second liquid flow channel 22, a third liquid flow channel 23, a fourth liquid flow channel 24, and a fifth liquid flow channel 25.

[0036] Referring to FIG. 4 , when the channel switching assembly 20 rotates to a first position relative to the microfluidic body 10, the microfluidic device 100 is in a first mode M1. At this point, the first liquid passage 21 of the channel switching assembly 20 connects the first main channel 11 and the second main channel 12. Fluid (e.g., a reagent) can be injected through the first main channel 11. The microfluidic body 10 is provided with a sensing area S between the first main channel 11 and the second main channel 12. The sensing area S connects the first main channel 11 and the second main channel 12, respectively. Fluid flowing out of the first main channel 11 can enter the sensing area S, then flow out of the sensing area S and enter the second main channel 12. Referring to FIG. 2 , the sensing device 200 includes a sensing chip 2001 arranged in a first direction X corresponding to the sensing area S, and the sensing chip 2001 can be wetted by fluid flowing through the sensing area S. The sensing chip 2001 is used to sense the fluid in the sensing area S and generate a corresponding signal. The first mode M1 is an administrator mode, which allows an administrator (e.g., a manufacturer) to perform pre-processing operations and introduce fluid into the sensing area S.

[0037] It is understood that the surface of the sensing chip 2001 has a microcavity structure (not shown). The administrator can pre-encapsulate fluid in the microcavity structure of the sensing chip 2001 in the first mode M1, so that the fluid forms a film layer, such as an amphiphilic molecular film, in the opening of the microcavity structure. The microcavity structure in the sensing chip 2001 needs to be filled with reagents through vacuum negative pressure. Since a vacuum environment needs to be created, this process is performed in the production factory. Before leaving the factory, the microfluidic device 100 is set to the administrator mode to pre-encapsulate the reagents in the sensing area S and fill them into the microcavity structure of the sensing chip 2001.

[0038] Please refer to Figure 5. When the channel switching component 20 is rotated to the second position relative to the microfluidic body 10, the microfluidic device 100 is in the second mode M2. At this time, the fourth liquid trough 24 of the channel switching component 20 connects the first main channel 11 and the second main channel 12, and the second liquid trough 22 connects the second main channel 12 and the first waste liquid channel 13. Fluid (such as reagent) can be injected through the first main channel 11. At the same time, the second waste liquid channel 14 is isolated from the second main channel 12. The fluid flowing out of the first main channel 11 can enter the sensing area S, then flow out of the sensing area S and enter the second main channel 12, and finally flow out of the microfluidic body 10 through the first waste liquid channel 13. Among them, the second mode M2 ​​is the administrator mode, and the administrator can extract the waste liquid generated by the pretreatment operation under the first mode M1 through the first waste liquid channel 13.

[0039] Referring to Figure 6 , when the channel switching assembly 20 rotates to the third position relative to the microfluidic body 10, the microfluidic device 100 is in the third mode M3. At this point, the first main channel 11, the second main channel 12, and the second waste liquid channel 14 are isolated from each other. Meanwhile, the second liquid passage 22 of the channel switching assembly 20 connects the second waste liquid channel 14 and the air channel 15. The third mode M3 can be a user mode, preventing external access to fluid from being injected into the sensing area S through the first main channel 11. For example, before transporting the microfluidic sensing system 1, the microfluidic device 100 can be switched to the third mode M3. In some embodiments, when the microfluidic device 100 is in the third mode M3, an administrator can also extract residual waste liquid from the first waste liquid channel 13 through the first waste liquid channel 13. While the third mode M3 is a user mode, it does not necessarily mean that only users can manipulate the microfluidic device 100 to switch to the third mode M3.

[0040] Please refer to Figure 7. When the channel switching assembly 20 rotates to the fourth position relative to the microfluidic body 10, the microfluidic device 100 is in the fourth mode M4. At this time, the third liquid trough 23 of the channel switching assembly 20 is connected to the first main channel 11 and the second main channel 12, and the fifth liquid trough 25 is connected to the second main channel 12 and the second waste liquid channel 14. At the same time, the air channel 15 and the second waste liquid channel 14 are isolated from each other. Fluid (such as reagents) can be injected into the first main channel 11 and enter the sensing area S, then flow out of the sensing area S and enter the second main channel 12, and then enter the second waste liquid channel 14 from the second main channel 12. Among them, the fourth mode M4 is a user mode for users to perform operations such as sample preparation, biochemical reactions, and result detection. Considering that discharging waste liquid at the fourth position may introduce bubbles into the sensing area S, the flow channel switching component 20 can be subsequently rotated back to the third position so that the second liquid flow channel 22 of the flow channel switching component 20 is connected to the second waste liquid flow channel 14 and the air flow channel 15. At this time, the waste liquid can be discharged outward through the second waste liquid flow channel 14.

[0041] As shown in Figures 2 to 7, in some embodiments, the microfluidic body 10 further includes a first main liquid injection port 11a connected to the first main channel 11, through which fluid can be injected into the first main channel 11. The microfluidic body 10 further includes a first waste port 13a connected to the first waste liquid channel 13. As shown in Figure 5, when the channel switching assembly 20 is rotated to the second position relative to the microfluidic body 10, the fluid that last flowed through the first waste liquid channel 13 can flow out of the microfluidic body 10 through the first waste port 13a. The microfluidic body 10 further includes a second waste port 14a connected to the second waste liquid channel 14. As shown in Figure 7, when the channel switching assembly 20 is rotated to the third position relative to the microfluidic body 10, the fluid that last flowed through the second waste liquid channel 14 can flow out of the microfluidic body 10 through the second waste port 14a. When viewed from the first direction X, the first main liquid injection port 11 a , the first waste port 13 a , and the second waste port 14 a are all exposed from the flow channel switching assembly 20 .

[0042] The microfluidic body 10 also has a first vent 15a that communicates with the air channel 15. As shown in Figure 6, when the channel switching assembly 20 is rotated to the third position relative to the microfluidic body 10, the second liquid transfer channel 22 of the channel switching assembly 20 connects the second waste liquid channel 14 and the air channel 15. At this point, when the user draws waste liquid through the second waste liquid channel 14, the first vent 15a serves as a balancing port, connected to the atmosphere.

[0043] As shown in Figures 1 and 2, in some embodiments, the microfluidic device 100 may further include a fluid storage component 30, which is connected to the microfluidic body 10 and communicates with the first main liquid injection port 11a. The fluid storage component 30 is used to temporarily store fluid, which can be injected into the first main flow channel 11 through the first main liquid injection port 11a. The microfluidic device 100 may also include a waste liquid storage component 40, which is connected to the microfluidic body 10 and communicates with the first waste outlet 13a. The waste liquid storage component 40 is used to temporarily store waste liquid flowing in from the first waste outlet 13a.

[0044] In the present application, in the first mode M1 and the second mode M2, the administrator can perform relevant pretreatment on the microfluidic device 100, and the waste liquid generated by the pretreatment operation can be discharged from the dedicated first waste liquid flow channel 13 without contaminating the user's second waste liquid flow channel 14, thereby eliminating the step of cleaning the second waste liquid flow channel 14 after the pretreatment operation.

[0045] The details of this application will be described in detail below in conjunction with the specific structure of the microfluidic sensing system 1.

[0046] Please refer to Figures 8 to 12. In some embodiments, the microfluidic body 10 includes a first cover plate 101, a flow channel plate 103, and a second cover plate 102, which are stacked in sequence in the first direction X. The sensing device 200 is connected to the side of the second cover plate 102 facing away from the flow channel plate 103. The flow channel plate 103 includes a first surface 103a and a second surface 103b arranged opposite to each other in the first direction X. The first cover plate 101 is covered on the first surface 103a, and the second cover plate 102 is covered on the second surface 103b. The flow channel plate 103 is made of a rigid material, and correspondingly, the first cover plate 101 and the second cover plate 102 can be made of a flexible material (such as silicone, rubber), etc., so as to improve the sealing effect. The flow channel plate 103 can also be made of a flexible material, and correspondingly, the first cover plate 101 and the second cover plate 102 can be made of a rigid material (such as metal). In other embodiments, the microfluidic body 10 with various flow channels can also be made using an integrated molding process. Alternatively, the flow channel plate 103 and one of the first cover plate 101 and the second cover plate 102 may be manufactured by an integral molding process, and then the other of the first cover plate 101 and the second cover plate 102 may be assembled to obtain the microfluidic body 10 .

[0047] Referring further to Figures 10 to 12 , the first main channel 11 can be formed by connecting multiple sections in series. For example, the first main channel 11 includes a first section 111, a second section 112, a third section 113, and a fourth section 114. The first section 111 and the second section 112 can be located on the first surface 103a of the flow channel plate 103, with the first section 111 and the second section 112 located on the first surface 103a isolated from each other. The third section 113 extends through the first surface 103a and the second surface 103b of the flow channel plate 103, and is connected to one end of the second section 112. The fourth section 114 can be located on the surface of the second cover plate 102 facing the flow channel plate 103, and is also connected to one end of the fourth section 114. When the flow channel switching assembly 20 connects the first section 111 and the second section 112 of the first main channel 11 during rotation, the sections of the first main channel 11 can be connected in series. Furthermore, since the first main channel 11 and the second main channel 12 are connected through the sensing area S, the first main channel 11 and the second main channel 12 are connected. By configuring the first main channel 11 as a double-layer channel structure, the space occupied by the microfluidic device 100 is reduced, thereby achieving miniaturization. It is understood that when the first cover plate 101 and the second cover plate 102 are placed on the flow channel plate 103, the sections of the first main channel 11 located on the surface of the flow channel plate 103 or the surface of the second cover plate 102 are closed in the first direction X, thereby forming the internal flow channel of the microfluidic body 10.

[0048] The second main channel 12 can be composed of multiple sections. For example, the second main channel 12 includes a first section 121, a second section 122, and a third section 123. The first section 121 of the second main channel 12 can be provided on the surface of the second cover plate 102 facing the flow channel plate 103. The second section 122 of the second main channel 12 can be provided through the first surface 103a and the second surface 103b of the flow channel plate 103, and the second section 122 is connected to one end of the first section 121. The third section 123 of the second main channel 12 can be provided on the first surface 103a of the flow channel plate 103, and the second section 122 can also be connected to one end of the third section 123. In this way, the second section 122 of the second main channel 12 connects the first section 121 to the third section 123, so that the first section 121, the second section 122, and the third section 123 are connected in series to form the second main channel 12. By configuring the second main channel 12 as a double-layer flow channel structure, it is helpful to further reduce the occupied space of the microfluidic device 100.

[0049] As shown in Figures 8 to 11, the fourth section 114 of the first main channel 11 connects to one side of the sensing area S through a first liquid-transmitting port 1140, while the first section 121 of the second main channel 12 connects to the opposite side of the sensing area S through a second liquid-transmitting port 1210. Viewed along the first direction X, the fourth section 114 of the first main channel 11 gradually expands from away from the sensing area S to closer to it, while the first section 121 of the second main channel 12 gradually expands from away from the sensing area S to closer to it. In other words, the width of the fourth section 114 of the first main channel 11 is greater on the side closer to the sensing area S than on the side farther from it, while the width of the first section 121 of the second main channel 12 is greater on the side closer to the sensing area S than on the side farther from it. This allows the fluid to flow into the sensing area S at a reduced velocity through the first liquid-transmitting port 1140, and then out of the sensing area S at a higher velocity through the second liquid-transmitting port 1210.

[0050] Furthermore, the bottom surface of the fourth section 114 of the first main channel 11 slopes downward from away from the sensing area S toward closer to the sensing area S, and the bottom surface of the first section 121 of the second main channel 12 slopes downward from away from the sensing area S toward closer to the sensing area S. In other words, the bottom surfaces of the fourth section 114 of the first main channel 11 and the first section 121 of the second main channel 12 are both inclined surfaces. This prevents the formation of right-angled corners at the junctions of the fourth section 114 and the third section 113, and the junctions of the first section 121 and the second section 121, thereby preventing fluid accumulation at the right-angled corners and ensuring smooth fluid flow. The inclined surface design also prevents excessive drop, thereby reducing the risk of bubble generation.

[0051] The first waste liquid flow channel 13 can be a single flow channel. In other embodiments, the first waste liquid flow channel 13 can also be composed of multiple flow channels, and the shape and arrangement of the channels can be changed according to actual needs.

[0052] The second waste liquid flow channel 14 can be composed of multiple flow channel sections. For example, the second waste liquid flow channel 14 includes a first section 141, a second section 142, a third section 143, a fourth section 144, and a fifth section 145. The first section 141 of the second waste liquid flow channel 14 can be provided on the first surface 103a of the flow channel plate 103. The second section 142 of the second waste liquid flow channel 14 can be provided through the first surface 103a and the second surface 103b, and the second section 142 can be connected to one end of the first section 141. The third section 143 of the second waste liquid flow channel 14 can be provided on the second surface 103b of the flow channel plate 103, and the second section 142 can also be connected to one end of the third section 143. The fourth section 144 of the second waste liquid flow channel 14 can be provided through the first surface 103a and the second surface 103b, and the fourth section 144 can be connected to the other end of the third section 143. The fifth section 145 of the second waste liquid flow channel 14 can be arranged on the first surface 103a of the flow channel plate 103, and the fourth section 144 can also be connected to one end of the fifth section 145. In this way, the first section 141, the second section 142, the third section 143, the fourth section 144 and the fifth section 145 are connected in series in sequence to form the second waste liquid flow channel 14. Among them, when the flow channel switching component 20 connects the third section 123 of the second main channel 12 and the first section 141 of the second waste liquid flow channel 14 during rotation, the second main channel 12 and the second waste liquid flow channel 14 can be connected to each other. Among them, by setting the second waste liquid flow channel 14 as a double-layer flow channel structure, it is beneficial to further reduce the occupied space of the microfluidic device 100. The third section 143 and the fifth section 145 of the second waste liquid flow channel 14 are both circuitous and extended flow channels, which are convenient for waste liquid collection.

[0053] The air flow channel 15 can be a single flow channel. In other embodiments, the air flow channel 15 can also be composed of multiple flow channels, and its shape and arrangement can be changed according to actual needs.

[0054] As shown in FIG8 , the microfluidic body 10 further comprises a pair of first flow channel connection ports 11 b connected to the first main channel 11 . One first flow channel connection port 11 b connects to the first section 111 of the first main channel 11 , and the other first flow channel connection port 11 b connects to the second section 112 of the first main channel 11 . The microfluidic body 10 further comprises a second flow channel connection port 12 b connected to the second main channel 12 . The microfluidic body 10 further comprises a pair of third flow channel connection ports 14 b connected to the second waste liquid flow channel 14 . The microfluidic body 10 further comprises a fourth flow channel connection port 15 b connected to the air flow channel 15 . The first vent 15 a and the fourth flow channel connection port 15 b can respectively connect to opposite ends of the air flow channel 15 . The microfluidic body 10 further comprises a pair of fifth flow channel connection ports 13 b connected to the first waste liquid flow channel 13 . Please also refer to FIG16 . The flow channel switching assembly 20 further comprises a second vent 26 . The first main liquid injection port 11a, the first vent 15a, and the various flow channel connection ports can all be provided on the first cover plate 101. Referring to Figures 1 and 2 , when viewed from the first direction X, the first to fifth flow channel connection ports 11b to 13b overlap with the flow channel switching assembly 20. That is, the flow channel switching assembly 20 covers the first to fifth flow channel connection ports 11b to 13b, allowing the liquid flow channel to connect different flow channels through the flow channel connection ports.

[0055] Figures 12 through 16 illustrate top views of the microfluidic device 100 when the flow channel switching assembly 20 is rotated to different positions. For ease of illustration, Figures 12 through 16 use solid lines to illustrate the flow channels within the microfluidic body 10, while dashed lines illustrate the position of the flow channel switching assembly 20 to avoid obscuring the internal flow channels or the flow channel connection ports. Specifically, referring to Figure 12 , when the flow channel switching assembly 20 is rotated relative to the microfluidic body 10 to the first position, the first liquid channel 21 of the flow channel switching assembly 20 connects to a pair of first flow channel connection ports 11b, interconnecting the first segment 111 and the second segment 112 of the first main flow channel 11, thereby sequentially connecting the first main flow channel 11, the sensing area S, and the second main flow channel 12. At this time, a certain amount of fluid can be injected into the fluid storage component 30. The fluid can be injected into the first section 111 of the first main channel 11 through the first main liquid injection port 11a, and then flow through the first liquid tank 21, the second section 112, the third section 113, the fourth section 114 of the first main channel 11, the sensing area S, the first section 121, the second section 122, and the third section 123 of the second main channel 12 in sequence (see Figures 9 to 11). In some embodiments, the internal air of the microfluidic device 100 can be first extracted by a negative pressure device, so that the entire microfluidic device 100 is in a negative pressure environment, and then the pressure is slowly released. Under the action of atmospheric pressure, the fluid in the fluid storage component 30 will slowly be injected into the first section 111 of the first main channel 11, and then flow through the flow channel subsequent to the first section 111.

[0056] Please refer to Figure 13. When the flow channel switching assembly 20 is rotated to the second position relative to the microfluidic body 10, the fourth liquid channel 24 of the flow channel switching assembly 20 is connected to the pair of first flow channel connection ports 11b, thereby connecting the first section 111 and the second section 112 of the first main flow channel 11 to each other. At the same time, the second liquid channel 22 of the flow channel switching assembly 20 is connected to the second flow channel connection port 12b and one of the fifth flow channel connection ports 13b, thereby connecting the second main flow channel 12 and the first waste liquid flow channel 13 to each other. At this time, the fluid flowing out of the fluid storage component 30 can be injected into the first section 111 of the first main channel 11 through the first main liquid injection port 11a, and then flow through the fourth liquid trough 24, the second section 112, the third section 113, the fourth section 114 of the first main channel 11, the sensing area S, the first section 121, the second section 122, the third section 123 of the second main channel 12, the second liquid trough 22 and the first waste liquid channel 13, and finally enter the waste liquid storage component 40 through the first waste outlet 13a of the first waste liquid channel 13 (see Figures 9 to 11). Since the waste liquid does not enter the second waste liquid channel 14 but enters the waste liquid storage component 40 through the first waste liquid channel 13 for collection, the second waste liquid channel 14 is ensured to be in a clean state when the microfluidic device 100 is delivered to the user.

[0057] Referring to Figure 14 , when the channel switching assembly 20 is rotated relative to the microfluidic body 10 to the third position, the second liquid channel 22 of the channel switching assembly 20 connects one of the third channel connection ports 14b and the fourth channel connection port 15b, thereby interconnecting the second waste liquid channel 14 and the air channel 15. Simultaneously, the first main channel 11, the second main channel 12, and the second waste liquid channel 14 are isolated from one another. At this point, the entire microfluidic device 100 is in the OFF mode, preventing external fluid from being injected into the sensing area S via the first main liquid injection port 11a and the first main channel 11. However, if the user switches the channel switching assembly 20 to the fourth position and completes liquid injection in the fourth position, the user can switch the channel switching assembly 20 back to the third position, allowing waste liquid to be withdrawn through the second waste port 14a of the second waste liquid channel 14. The first vent 15a of the air channel 15 now serves as a balancing port connected to the atmosphere. On the other hand, when the channel switching assembly 20 is rotated to the third position relative to the microfluidic body 10, the second vent 26 of the channel switching assembly 20 can be connected to another fifth channel connection port 13b. At this time, the administrator can also extract the waste liquid in the first waste liquid channel 13 through the first waste outlet 13a of the first waste liquid channel 13. At this time, the second vent 26 serves as a balance port to connect to the atmosphere.

[0058] Referring to Figure 15 , when the channel switching assembly 20 is rotated to the fourth position relative to the microfluidic body 10, the third liquid transfer groove 23 of the channel switching assembly 20 connects to the pair of first channel connection ports 11b, thereby interconnecting the first section 111 and the second section 112 of the first main channel 11. Simultaneously, the fifth liquid transfer groove 25 connects to the second channel connection port 12b and the third channel connection port 14b of the second waste channel 14, thereby interconnecting the second main channel 12 and the second waste channel 14. At this point, the entire microfluidic device 100 is in the open (ON) mode, allowing external fluid to be added to the sensing area S. At this time, the fluid flowing out of the fluid storage component 30 can be slowly injected into the first section 111 of the first main channel 11 through the first main liquid injection port 11a, and then flow through the third liquid trough 23, the second section 112, the third section 113, the fourth section 114 of the first main channel 11, the sensing area S, the first section 121, the second section 122 and the third section 123 of the second main channel 12, the fifth liquid trough 25, the first section 141, the second section 142, the third section 143, the third section 143, the fourth section 144 and the fifth section 145 of the second waste liquid channel 14 (see Figures 9 to 11). When the channel switching assembly 20 is in the fourth position, the air channel 15 is isolated from the first section 141 of the second waste liquid channel 14 and is not connected to each other. Therefore, when waste liquid is subsequently extracted in the third position, the waste liquid will only flow into the second section 142 and its subsequent channels through the first section 141 of the second waste liquid channel 14 in a one-way manner and will not be discharged through the air channel 15.

[0059] As shown in Figure 10, in some embodiments, the multiple flow channels of the microfluidic body 10 may further include a secondary flow channel 17, which may be provided on the second surface 103b of the flow channel plate 103. Referring to Figure 3, at least one of the first main channel 11 and the second main channel 12 forms a buffer zone H, that is, the number of the buffer zones H is at least one. When viewed from the first direction X, the buffer zones H and the secondary flow channels 17 overlap. The microfluidic device 100 may further include at least one membrane 50 and a conductive sheet 60. The number of membranes 50 corresponds to the number of buffer zones H. Each membrane 50 is provided between the secondary flow channel 17 and a buffer zone H to separate the secondary flow channel 17 from the buffer zone H. For example, the bottom wall of the buffer zone H may form at least one opening (not shown) to connect the secondary flow channel 17, and each membrane 50 covers one opening and fits the opening. The membrane 50 can be infiltrated by the fluid in the secondary flow channel 17 and is configured to allow ion transfer between the fluid in the secondary flow channel 17 and the fluid in the buffer zone H, and the fluid in the buffer zone H can only exchange ions with the fluid in the secondary flow channel 17. The conductive sheet 60 is located below one of the membranes 50. The conductive sheet 60 can be infiltrated by the fluid in the secondary flow channel 17 and is used to transmit the signal generated by the ion exchange in each membrane 50 to the outside. In the first mode M1 or the second mode M2, the administrator can inject the required fluid (such as detection liquid) into the secondary flow channel 17, so that when the subsequent user injects the reagent into the first main channel 11, the reagent in the buffer zone H can exchange ions with the detection liquid in the secondary flow channel 17 located below the buffer zone H. The membrane 50 is made of a highly permeable membrane or a semi-permeable membrane, such as an ion exchange membrane, a proton exchange membrane, etc. The conductive sheet 60 can be made of a conductive metal sheet. The membrane 50 and the conductive sheet 60 can be fixed to the flow channel plate 103 by hot melting or bonding, thereby improving the stability of the structure. In other embodiments, the secondary flow channel 17 may also be formed in a sealed container provided with the membrane 50 and the conductive sheet 60 . The sealed container is embedded in the microfluidic body 10 and may even be detachably connected to the microfluidic body 10 .

[0060] In some embodiments, the second section 112 of the first main channel 11 forms a buffer zone H located upstream of the sensing area S, while the third section 123 of the second main channel 12 forms another buffer zone H located downstream of the sensing area S. As shown in FIG3 , when viewed from the first direction X, the buffer zone H can be configured to first increase and then decrease along the extension direction of the first main channel 11 or the second main channel 12. In another embodiment, there can be only one buffer zone H, located upstream or downstream of the sensing area S.

[0061] As shown in FIG8 , the microfluidic body 10 is further provided with a first secondary liquid injection port 17a and a second secondary liquid injection port 17b, both of which are connected to the secondary flow channel 17. The first secondary liquid injection port 17a and the second secondary liquid injection port 17b can be both provided on the first cover plate 101. As shown in FIG9 and FIG10 , in order to connect the first secondary liquid injection port 17a and the second secondary liquid injection port 17b with the secondary flow channel 17 provided on the second surface 103b of the flow channel plate 103, the flow channel plate 103 can also be provided with a first through hole 17c and a second through hole 17d, both of which penetrate the first surface 103a and the second surface 103b. The first secondary liquid injection port 17a and the first through hole 17c are correspondingly arranged in the first direction X, and the first through hole 17c is connected to the secondary flow channel 17, so that the first secondary liquid injection port 17a can connect to the secondary flow channel 17 through the first through hole 17c. The second auxiliary liquid injection port 17b and the second through hole 17d are correspondingly arranged in the first direction X, and the second through hole 17d is connected to the secondary flow channel 17, so that the second auxiliary liquid injection port 17b can be connected to the secondary flow channel 17 through the second through hole 17d. One of the first auxiliary liquid injection port 17a and the second auxiliary liquid injection port 17b can be used as an injection port, and fluid can be injected into the secondary flow channel 17 through one of the first auxiliary liquid injection port 17a and the second auxiliary liquid injection port 17b. The other of the first auxiliary liquid injection port 17a and the second auxiliary liquid injection port 17b is used to exhaust air in the secondary flow channel 17, so as to ensure that the fluid can be smoothly injected into the secondary flow channel 17. In some embodiments, the microfluidic device 100 further includes a sealing patch 70. After the fluid is injected into the secondary flow channel 17, the sealing patch 70 can be used to cover the first auxiliary liquid injection port 17a and the second auxiliary liquid injection port 17b to prevent leakage of the sensing liquid in the secondary flow channel 17. Furthermore, the sealing sticker 70 itself may be sticky, and the sealing sticker 70 may be adhered to the first cover plate 101 , thereby improving the sealing performance.

[0062] In some embodiments, the first cover plate 101 and the second cover plate 102 can both be set to transparent material, so that it is convenient for the administrator or user to observe the flow of fluid in each flow channel through the first cover plate 101 and the second cover plate 102, and it is also convenient for the pipeline operator or user to observe the situation in the sensing area S through the first cover plate 101 and the second cover plate 102.

[0063] Referring to Figures 16 and 17 , in some embodiments, the flow channel switching assembly 20 includes a rotating body 201 and a sealing plate 202 . The rotating body 201 is rotatably connected to the first cover plate 101 of the microfluidic body 10 . The sealing plate 202 is fixed to the surface of the rotating body 201 facing the first cover plate 101 and can thus rotate with the rotating body 201 . The surface of the sealing plate 202 facing away from the rotating body 201 can be in contact with the first cover plate 101 . In other words, the sealing plate 202 is sandwiched between the rotating body 201 and the microfluidic body. The first to fifth liquid flow channels 21 to 25 can all be provided on the sealing plate 202, and the second vent 26 can be provided through the sealing plate 202 and the rotating body 201. The rotating body 201 can be made of a hard material, and the sealing plate 202 can be made of an elastic material (such as silicone or rubber). The sealing plate 202 can be fixed to the rotating body 201 by heat fusion, ultrasonic welding, laser welding, gluing, or the like.

[0064] The flow channel switching assembly 20 may further include a limiting component 203, which protrudes from the surface of the rotating body 201 facing the first cover plate 101. When the rotating body 201 rotates relative to the microfluidic body 10, the limiting component 203 rotates with the rotating body 201. As shown in Figures 17 and 18, correspondingly, a chute 1010 may also be provided on the first cover plate 101, and at least a portion of the limiting component 203 is embedded in the chute 1010. During the rotation of the flow channel switching assembly 20 relative to the microfluidic body 10, the limiting component 203 slides along the chute 1010. In order to adapt to the movement trajectory of the limiting component 203, the chute 1010 is arc-shaped. The cooperation between the limiting component 203 and the chute 1010 limits the rotation angle of the rotating body 201 relative to the microfluidic body 10, allowing the flow channel switching assembly 20 to switch between the first position, the second position, the third position, and the fourth position. In other embodiments, the limiting component 203 and the slide groove 1010 may be omitted. In this case, the rotation angle of the rotating body 201 relative to the microfluidic body 10 may be positioned by other external structures.

[0065] The chute 1010 may include a first chute section 1011, a second chute section 1012, and a third chute section 1013, which are connected in sequence. The limiting component 203 is configured to slide within the first chute section 1011, the second chute section 1012, and the third chute section 1013. When the limiting component 203 is located at the end of the first chute section 1011 facing away from the second chute section 1012, the flow channel switching assembly 20 is in a first position; when the limiting component 203 is located at the connection between the first chute section 1011 and the second chute section 1012, the flow channel switching assembly 20 is in a second position; when the limiting component 203 is located at the connection between the second chute section 1012 and the third chute section 1013, the flow channel switching assembly 20 is in a third position; and when the limiting component 203 is located at the end of the third chute section 1013 facing away from the second chute section 1012, the flow channel switching assembly 20 is in a fourth position. In some embodiments, the flow channel switching assembly 20 allows a rotation angle of 0° to 270°. When the limiting component 203 is located at the end of the first slot section 1011 away from the second slot section 1012, the rotation angle of the flow channel switching assembly 20 is 0°, and the flow channel switching assembly 20 rotates to the first position; the flow channel switching assembly 20 is rotated 90° clockwise, and the limiting component 203 is located at the connection between the first slot section 1011 and the second slot section 1012, and the flow channel switching assembly 20 rotates to the second position; the flow channel switching assembly 20 is further rotated 90° clockwise, and the limiting component 203 is located at the connection between the second slot section 1012 and the third slot section 1013, and the flow channel switching assembly 20 is rotated to the third position; the flow channel switching assembly 20 is further rotated 90° clockwise, and the limiting component 203 is located at the end of the third slot section 1013 away from the second slot section 1012, and the flow channel switching assembly 20 is rotated to the fourth position. It is understandable that the rotation angle range and the limit positions of the flow channel switching component 20 are not limited to the above embodiments. The rotation angle range and the limit positions can be adjusted accordingly by adjusting the arc length of the slide groove 1010 and the proportion of each groove segment.

[0066] In some embodiments, the depth of the first slot segment 1011 is equal to the depth of the second slot segment 1012. A recess R is provided at the junction of the first and second slot segments 1011, 1012, and this recess R is used to limit the position-limiting component 203 to the second position. Furthermore, the depth of the second slot segment 1012 is less than the depth of the third slot segment 1013 (i.e., there is a step between the second and third slot segments 1012, 1013). Accordingly, the position-limiting component 203 is a preloaded spring pin. Therefore, when the flow channel switching assembly 20 rotates to the third position, the depth of the third slot segment 1013 increases, causing the preloaded spring pin to pop out and prevent it from sliding back from the third slot segment 1013 to the second slot segment 1012. In other words, the step between the second and third slot segments 1012, 1013, prevents the position-limiting component 203 from sliding back in the opposite direction to the first and second slot segments 1011, 1012. Therefore, the user can only operate in the third mode M3 and the fourth mode M4, thereby avoiding erroneous operation that may be caused by the limiting component 203 sliding back to the first slot section 1011 and the second slot section 1012 in the opposite direction.

[0067] As shown in Figures 1 and 2, in some embodiments, the fluid storage component 30 can be detachably connected to the microfluidic body 10 by means of snapping, bonding, fastening with fasteners, etc., to ensure that no leakage occurs during the injection process. In some embodiments, the fluid storage component 30 includes a fluid storage body 31 and a sealing plug 32 connected to the fluid storage body 31, and the fluid storage body 31 has a space for accommodating fluid. The fluid storage body 31 is also provided with an opening 310 (shown in Figures 12 to 15) for communicating with the first main injection port 11a, and the fluid can enter the first main flow channel 11 through the opening 310 and the first main injection port 11a. Please refer to Figures 20 and 21. The sealing plug 32 includes a cover body 321 and a plug body 322 provided in the cover body 321. The cover 321 has a top wall 3211 and side walls 3212 arranged around the edges of the top wall 3211. The plug 322 is accommodated in the space enclosed by the top wall 3211 and the side walls 3212 and is fixed to the top wall 3211. The side walls 3212 of the cover 321 are internally threaded, and the outer wall of the fluid storage body 31 is externally threaded, so that the cover 321 can be screwed into the fluid storage body 31 and fixed to the fluid storage body 31 through threaded engagement. The end of the plug 322 is provided with a flexible material 3220 (such as silicone or rubber). When the cover 321 is connected to the fluid storage body 31, the flexible material 3220 is used to seal the first main liquid inlet 11a, thereby sealing the first main liquid inlet 11a when liquid is not required to be injected through the first main liquid inlet 11a. Furthermore, a vent hole 3210 is provided through the top wall 3211 of the cover 321 , thereby preventing the gas in the plug 322 from being pushed into the flow channel of the microfluidic device 100 when the cover 321 is screwed in.

[0068] As shown in Figures 1 and 2, the waste liquid storage component 40 can be detachably connected to the microfluidic body 10 by means of snapping, bonding, or fastening with fasteners, ensuring that no leakage occurs during waste liquid collection. For example, the microfluidic body 10 can be provided with a slot 16 that extends through the first cover plate 101 and further extends through the flow channel plate 103. The waste liquid storage component 40 can include a waste liquid storage body 41 and snaps 41 disposed on opposite sides of the waste liquid storage body 41. The waste liquid storage body 41 has a space for receiving waste liquid, and the snaps 41 can be elastically deformed relative to the waste liquid storage body 41. The waste liquid storage component 40 can be inserted into the slot 16 by pressing the snaps 41, after which the snaps 41 elastically return, allowing the waste liquid storage component 40 to snap into the slot 16. In some embodiments, a side wall of the waste liquid storage body 41 is provided with a first liquid inlet groove 411 and a second liquid inlet groove 412 that are interconnected. The first liquid inlet groove 411 extends through the side wall along the first direction X and communicates with the first waste outlet 13a. The second liquid inlet groove 412 communicates with the first liquid inlet groove 411 and the space for storing waste liquid in the waste liquid storage body 41 along another direction perpendicular to the first direction X. Therefore, waste liquid discharged through the first waste outlet 13 can enter the space for storing waste liquid in the waste liquid storage body 41 through the first liquid inlet groove 411 and the second liquid inlet groove 412 in sequence.

[0069] As shown in Figures 1, 2, and 11, the sensing device 200 further includes a carrier plate 2002 for supporting a sensing chip 2001. The carrier plate 2002 is stacked on a side of the microfluidic body 10 facing away from the flow channel switching assembly 20 in a first direction X. The sensing chip 2001 is fixed to a surface of the carrier plate 2002 facing the microfluidic body 10. The carrier plate 2002 can be removably connected to the microfluidic body 10 by snapping, bonding, or fastener fixation. In some embodiments, the carrier plate 2002 is removably connected to the microfluidic body 10 by bolts.

[0070] The sensing device 200 also includes an electrical conductor 2003 fixed to the carrier 2002. The top of the electrical conductor 2003 abuts against the conductive sheet 60. Therefore, the signal generated by the detection liquid in the secondary flow channel 17 and the fluid in the buffer zone H due to ion exchange can be transmitted to the carrier 2002 through the conductive sheet 60 and the electrical conductor 2003. Secondly, the signal generated by the sensing chip 2001 is also transmitted to the carrier 2002. The carrier 2002 can also further send the received signal to a signal acquisition and analysis instrument to complete the detection and analysis. In some instances, the electrical conductor 2003 can be a probe or an electrode, as long as it can be electrically connected to the conductive sheet 60 and conduct signals. The carrier 2002 can be a circuit board to ensure that it can form signal transmission with the sensing chip 2001 and the electrical conductor 2003. The sensing chip 2001 can be a biochip.

[0071] The microfluidic sensing system 1 also includes a sealing gasket 300. The sealing gasket 300 is disposed between the carrier plate 2002 and the microfluidic body 10 and surrounds the sensing area S, thereby preventing fluid leakage between the microfluidic device 100 and the sensing device 200. In some embodiments, the sealing gasket 300 may be annular, and the sensing chip 2001 may extend into the space within the sealing gasket 300 and come into contact with the fluid in the sensing area S. Referring to FIG. 19 , the second cover plate 102 of the microfluidic body 10 may further include an annular groove 1020. The sealing gasket 300 is provided with ribs 301, which are configured to be inserted into the annular groove 1020, thereby better positioning the sealing gasket 300 between the carrier plate 2002 and the microfluidic body 10.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A microfluidic device, characterized in that: include: The microfluidic body is provided with a first main flow channel, a second main flow channel, a first waste liquid flow channel and a second waste liquid flow channel; as well as A flow channel switching component, rotatably connected to the microfluidic body; The flow channel switching component is used to rotate to a first position, thereby connecting the first main flow channel and the second main flow channel; the flow channel switching component is also used to rotate to a second position, thereby connecting the first main flow channel, the second main flow channel and the first waste liquid flow channel. When the flow channel switching component is in the second position, the second main flow channel and the second waste liquid flow channel are isolated from each other.

2. The microfluidic device according to claim 1, wherein The flow channel switching assembly is further configured to rotate to a third position, thereby isolating the first main flow channel, the second main flow channel, and the second waste liquid flow channel from each other.

3. The microfluidic device according to claim 2, wherein The microfluidic body is further provided with an air flow channel and a first vent connected to the air flow channel, the first vent is also connected to the atmosphere, and when the flow channel switching component is rotated to the third position, the second waste liquid flow channel is connected to the air flow channel.

4. The microfluidic device according to claim 3, wherein The flow channel switching component is provided with a second vent, which is connected to the atmosphere. When the flow channel switching component is rotated to the third position, the second vent is connected to the first waste liquid flow channel.

5. The microfluidic device according to claim 3, wherein The flow channel switching assembly is further used to rotate to a fourth position, thereby connecting the first main flow channel, the second main flow channel and the second waste liquid flow channel.

6. The microfluidic device according to claim 1, wherein The microfluidic body is further provided with a first waste outlet communicating with the first waste liquid flow channel, and the microfluidic device further comprises: The waste liquid storage component is connected to the microfluidic body and communicated with the first waste outlet.

7. The microfluidic device according to claim 6, wherein The waste liquid storage component is detachably connected to the microfluidic body.

8. The microfluidic device according to claim 7, wherein The microfluidic body is also provided with a card slot, and the waste liquid storage component includes a waste liquid storage body and a clip provided on opposite sides of the waste liquid storage body. The waste liquid storage body is provided with a space for accommodating waste liquid, and the waste liquid storage body is used to be inserted into the card slot, and the clip is used to snap the waste liquid storage body into the card slot.

9. The microfluidic device according to claim 8, wherein A first liquid inlet groove and a second liquid inlet groove are provided on one side wall of the waste liquid storage body. The first liquid inlet groove penetrates the side wall along the thickness direction of the microfluidic device and is connected to the first waste outlet. The second liquid inlet groove is connected to the first liquid inlet groove and the space along another direction perpendicular to the thickness direction.

10. The microfluidic device according to claim 1, wherein The microfluidic body is further provided with a first main liquid injection port communicating with the first main flow channel, and the microfluidic device further comprises: The fluid storage component is connected to the microfluidic body and communicated with the first main liquid injection port.

11. The microfluidic device according to claim 10, wherein: The fluid storage component includes a fluid storage body and a sealing plug detachably connected to the fluid storage body. The fluid storage body is provided with an opening for communicating with the first main liquid filling port.

12. The microfluidic device according to claim 11, wherein The sealing plug includes a cover body and a plug body arranged in the cover body, the cover body has a top wall and side walls arranged around the edge of the top wall, the plug body is accommodated in the space formed by the top wall and the side walls, the plug body is fixed to the top wall, and a flexible material is provided at the end of the plug body, and the flexible material is used to seal the first main liquid filling port.

13. The microfluidic device according to claim 12, wherein: The top wall is provided with a vent hole.

14. The microfluidic device according to claim 5, wherein The flow channel switching assembly is provided with a first liquid passage trough, a second liquid passage trough, a third liquid passage trough, a fourth liquid passage trough, and a fifth liquid passage trough. When the flow channel switching assembly is switched to the first position, the first liquid passage trough is connected to the first main flow channel and the second main flow channel; When the flow channel switching component is switched to the second position, the second liquid flow channel is connected to the second main flow channel and the first waste liquid flow channel; when the flow channel switching component is switched to the third position, the second liquid flow channel is connected to the second waste liquid flow channel and the air flow channel; when the flow channel switching component is switched to the fourth position, the third liquid flow channel is connected to the first main flow channel and the second main flow channel, and the fifth liquid flow channel is connected to the second main flow channel and the second waste liquid flow channel.

15. The microfluidic device according to claim 5, wherein The microfluidic body further includes a sensing area disposed between the first main channel and the second main channel, and a corresponding signal is generated after the fluid in the sensing area is sensed.

16. The microfluidic device according to claim 15, wherein The microfluidic body also includes a secondary flow channel, at least one of the first main flow channel and the second main flow channel forms a buffer zone, and when viewed along the thickness direction of the microfluidic device, the buffer zone and the secondary flow channel overlap; the microfluidic device also includes at least one membrane, each of the membranes is arranged between the secondary flow channel and a buffer zone, and the membrane allows ion transfer between the fluid in the secondary flow channel and the fluid in the buffer zone.

17. The microfluidic device according to claim 16, wherein: The buffer zone is located upstream of the sensing region.

18. The microfluidic device according to claim 17, wherein: The buffer zone is also located downstream of the sensing region.

19. The microfluidic device according to claim 16, wherein: The microfluidic body is further provided with a first auxiliary liquid injection port and a second auxiliary liquid injection port, both of which are connected to the auxiliary flow channel. The microfluidic device also includes a sealing patch, which is used to seal the first auxiliary liquid injection port and the second auxiliary liquid injection port.

20. The microfluidic device according to claim 5, wherein The channel switching assembly includes a rotating body and a limiting component protruding from the rotating body, the microfluidic body is provided with a slide groove, at least part of the limiting component is slidably arranged in the slide groove, and the slide groove includes a first groove section, a second groove section and a third groove section connected in sequence; when the limiting component is located at the end of the first groove section away from the second groove section, the channel switching assembly is in the first position; when the limiting component is located at the connection between the first groove section and the second groove section, the channel switching assembly is in the second position; when the limiting component is located at the connection between the second groove section and the third groove section, the channel switching assembly is in the third position; when the limiting component is located at the end of the third groove section away from the second groove section, the channel switching assembly is in the fourth position.

21. The microfluidic device according to claim 20, wherein: The depth of the first slot section is equal to the depth of the second slot section. A recess is provided at the connection between the first slot section and the second slot section. The recess is used to limit the limiting component to the second position.

22. The microfluidic device according to claim 20, wherein: The depth of the second groove section is smaller than that of the third groove section. The limiting component is a pre-loaded spring pin. When the flow channel switching assembly rotates to the third position, the pre-loaded spring pin pops out.

23. The microfluidic device according to claim 15, wherein The microfluidic body includes a first cover plate, a flow channel plate and a second cover plate which are sequentially stacked and fixed to each other, and the flow channel switching assembly is rotatably connected to the first cover plate.

24. The microfluidic device according to claim 23, wherein The flow channel plate includes a first surface and a second surface arranged opposite to each other, the first surface faces the first cover plate, and the second surface faces the second cover plate; the first main flow channel includes a first section, a second section, a third section and a fourth section; in the first main flow channel, the first section and the second section are arranged on the first surface, the third section runs through the first surface and the second surface, the fourth section is arranged on the second cover plate, and the third section is connected to the second section and the fourth section; the fluid switching component is used to connect the first section and the second section when rotating.

25. The microfluidic device according to claim 24, wherein The second main channel includes a first section, a second section and a third section connected in sequence; in the second main channel, the first section is arranged on the second cover plate, the second section runs through the first surface and the second surface, and the third section is arranged on the first surface; the sensing area is connected between the fourth section of the first main channel and the first section of the second main channel.

26. The microfluidic device according to claim 24, wherein The second waste liquid flow channel includes a first section, a second section, a third section, a fourth section and a fifth section connected in sequence; in the second waste liquid flow channel, the first section and the fifth section are both arranged on the first surface, the second section and the fourth section both pass through the first surface and the second surface, and the third section is arranged on the second surface.

27. The microfluidic device according to claim 25, wherein Observing along the thickness direction of the microfluidic device, the fourth section of the first main channel is gradually expanded from away from the sensing area to closer to the sensing area, and the first section of the second main channel is gradually expanded from away from the sensing area to closer to the sensing area.

28. The microfluidic device according to claim 23, wherein The flow channel plate is made of a rigid material, and the first cover plate and the second cover plate are made of a flexible material; or the flow channel plate is made of a flexible material, and the first cover plate and the second cover plate are made of a rigid material.

29. A microfluidic sensing system, characterized in that: The microfluidic sensing system comprises a sensing device and the microfluidic device according to any one of claims 1 to 28, wherein the sensing device is used to sense the fluid in the microfluidic device and generate a corresponding signal.

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