A double-layer microfluidic chip

Abstract

The utility model provides a kind of double-layer microfluidic chip, comprising: upper panel, lower panel and fixed module;The upper surface of upper panel is provided with mixing groove body, and the bottom of the outlet end of mixing groove body is provided with through hole;The upper surface of lower panel is provided with separation groove body;First fixed groove and second fixed groove are respectively set on the left and right two sides of fixed module, first fixed groove extends horizontally to form the first accommodating cavity for accommodating upper panel in fixed module, second fixed groove extends horizontally to form the second accommodating cavity for accommodating lower panel in fixed module, there is flow guide channel between first accommodating cavity and second accommodating cavity, when upper panel is placed in first accommodating cavity, through hole and the position of flow guide channel correspond, when lower panel is placed in first accommodating cavity, sample inlet of separation groove body is located below flow guide channel.The present application is used for the rapid processing of saliva sample and the efficient sorting of CGRP, reduces the artificial cost while improving the processing rate.

Description

Technical Field

[0001] This utility model belongs to the field of medical device technology, specifically relating to a dual-layer microfluidic chip. Background Technology

[0002] Early diagnosis and monitoring of migraines rely on the detection of biomarkers, with CGRP (calcitonin gene-related peptide) being a key indicator. However, CGRP is unstable and easily degraded in saliva. Traditional detection methods (such as ELISA) typically require complex sample pretreatment (e.g., centrifugation, cryopreservation), resulting in long testing cycles and cumbersome procedures, making it difficult to meet the needs of point-of-care testing (POCT). Furthermore, existing saliva processing methods (e.g., filtration, centrifugation, or chemical precipitation) suffer from large sample volumes, low processing efficiency, and susceptibility to interference from impurities, limiting the accuracy and clinical application of CGRP detection.

[0003] Therefore, how to provide a dual-layer microfluidic chip that reduces costs while increasing processing speed is a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0004] In view of the above-mentioned problems, the present invention aims to provide a dual-layer microfluidic chip that solves at least one of the above-mentioned technical problems.

[0005] To address the aforementioned technical problems, this utility model provides a dual-layer microfluidic chip, the dual-layer microfluidic chip comprising: The assembly comprises an upper panel, a lower panel, and a fixing module. The upper surface of the upper panel has a mixing tank, with a through hole at the bottom of the outlet end of the mixing tank. The upper surface of the lower panel has a separation tank. The fixing module has a first fixing slot and a second fixing slot on its left and right sides, respectively. The first fixing slot extends horizontally into the fixing module to form a first receiving cavity for accommodating the upper panel, and the second fixing slot extends horizontally into the fixing module to form a second receiving cavity for accommodating the lower panel. A longitudinally arranged guide channel is provided between the bottom of the first receiving cavity and the top of the second receiving cavity. When the upper panel is detachably placed in the first receiving cavity, the through hole corresponds to the position of the guide channel. When the lower panel is detachably placed in the first receiving cavity, the sample inlet of the separation tank is located below the guide channel.

[0006] Preferably, the mixing tank includes: a saliva inlet, a diluent inlet, a saliva inlet channel, a diluent inlet channel, and a serpentine mixing channel; the saliva inlet and the diluent inlet are arranged at intervals, the center-line distance between the saliva inlet and the diluent inlet is 4 cm, one end of the saliva inlet is connected to the saliva inlet channel, one end of the diluent inlet is connected to the diluent inlet channel, the other ends of the saliva inlet channel and the diluent inlet channel converge to the inlet end of the serpentine mixing channel, and the bottom wall of the outlet end of the serpentine mixing channel is provided with the through hole.

[0007] Preferably, the serpentine mixing channel has 4 bends.

[0008] Preferably, a filter membrane is provided at the connection between the saliva inlet and the saliva inlet channel.

[0009] Preferably, the separation tank includes: a mixing liquid inlet, a spiral separation channel, a straight channel, an inner edge groove, and an outer edge groove; the mixing liquid inlet is located at the central end of the spiral separation channel and is connected to the spiral separation channel; the outer end of the spiral separation channel is connected to one end of the straight channel; the other end of the straight channel extends radially to form an asymmetrical inner edge groove and an outer edge groove; the inner edge groove and the outer edge groove are independent of each other; the flow channel cross-section of the inner edge groove and the outer edge groove is gradually widening; and the straight channel is arranged along the tangential direction of the outer edge end.

[0010] Preferably, the spiral separation channel has 5 spiral turns.

[0011] Preferably, the saliva inlet, the diluent inlet, and the mixing liquid inlet are all circular groove structures, and the diameters of the saliva inlet and the diluent inlet are twice the diameter of the mixing liquid inlet.

[0012] Preferably, the maximum width of the outer edge groove is greater than the maximum width of the inner edge groove, and the channel width of the serpentine mixing channel is less than the channel width of the spiral separation channel.

[0013] Beneficial effects: This utility model provides a dual-layer microfluidic chip, specifically comprising: an upper panel, a lower panel, and a fixing module; a mixing tank is provided on the upper surface of the upper panel, and a through hole is provided at the bottom of the outlet end of the mixing tank; a separation tank is provided on the upper surface of the lower panel; a first fixing groove and a second fixing groove are respectively provided on the left and right sides of the fixing module, the first fixing groove extending horizontally into the fixing module to form a first receiving cavity for accommodating the upper panel, and the second fixing groove extending horizontally into the fixing module to form a second receiving cavity for accommodating the lower panel; a longitudinally arranged flow channel is provided between the bottom of the first receiving cavity and the top of the second receiving cavity; when the upper panel is detachably placed in the first receiving cavity, the through hole corresponds to the position of the flow channel, and when the lower panel is detachably placed in the first receiving cavity, the sample inlet of the separation tank is located below the flow channel. This application achieves longitudinal stacking by setting an upper panel and a lower panel to respectively support the mixing and separation functional modules, and by using the positioning structure of the fixing module. When the upper panel is inserted into the first receiving cavity, its bottom through-hole automatically aligns with the inlet of the flow channel, and the mixed sample flows vertically into the lower layer under gravity. The sample inlet of the separation tank of the lower panel is located directly below the outlet of the flow channel, ensuring that the fluid directly enters the separation process. The fixing slot design on both sides of the fixing module allows the upper and lower panels to be disassembled and replaced independently. When the mixing tank becomes clogged or the separation tank needs cleaning, the corresponding panel can be removed for processing. The longitudinal arrangement of the flow channel reduces the lateral span of the fluid transmission path, avoiding flow rate attenuation caused by excessively long horizontal channels. The dual-layer microfluidic chip provided in this application is used for rapid processing of saliva samples and efficient sorting of CGRP, reducing labor costs while increasing processing speed.

[0014] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this utility model more obvious and understandable, specific embodiments of this utility model are given below. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A perspective view of a dual-layer microfluidic chip provided in an embodiment of this utility model; Figure 2 This is a schematic diagram of the structure of the fixing module provided in an embodiment of the present utility model; Figure 3This is a schematic diagram of the structure of the upper panel provided in an embodiment of the present utility model; Figure 4 This is a schematic diagram of the structure of the lower panel provided in an embodiment of the present utility model.

[0017] Figure label: 1. Top panel 11. Saliva inlet; 12. Diluent Inlet 13. Saliva sample inlet channel; 14. Diluent injection channel; 15. Serpentine mixing channel; 16. Filter membrane; 17. Through hole; 2. Lower panel; 21. Inlet of the mixed liquid; 22. Spiral separation channel; 23. Straight-line channel; 24. Inner edge groove; 25. Outer edge groove; 3. Fixed module; 31. First accommodating cavity; 32. Second accommodating cavity; 33. Flow channel. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] Example 1 Please see Figure 1-4This embodiment provides a dual-layer microfluidic chip, which specifically includes: an upper panel 1, a lower panel 2, and a fixing module 3; a mixing tank is provided on the upper surface of the upper panel 1, and a through hole 17 is provided at the bottom of the outlet end of the mixing tank; a separation tank is provided on the upper surface of the lower panel 2; a first fixing groove and a second fixing groove are respectively provided on the left and right sides of the fixing module 3, the first fixing groove extends horizontally into the fixing module 3 to form a first receiving cavity 31 for accommodating the upper panel 1, and the second fixing groove extends horizontally into the fixing module 3 to form a second receiving cavity 32 for accommodating the lower panel 2, and a longitudinally arranged guide channel 33 is provided between the bottom of the first receiving cavity 31 and the top of the second receiving cavity 32. When the upper panel 1 is detachably placed in the first receiving cavity 31, the through hole 17 corresponds to the position of the guide channel 33, and when the lower panel 2 is detachably placed in the first receiving cavity 31, the sample inlet of the separation tank is located below the guide channel 33.

[0020] Specifically, this application uses an upper panel 1 and a lower panel 2 to respectively support the mixing and separation functional modules, and achieves vertical stacking through the positioning structure of the fixing module 3. When the upper panel 1 is inserted into the first accommodating cavity 31, its bottom through hole 17 automatically aligns with the inlet of the guide channel 33, and the mixed sample flows vertically into the lower layer under the action of gravity. The sample inlet of the separation tank of the lower panel 2 is located directly below the outlet of the guide channel 33, ensuring that the fluid directly enters the separation process. The fixing slot design on both sides of the fixing module 3 allows the upper and lower panels 2 to be disassembled and replaced independently. When the mixing tank becomes blocked or the separation tank needs cleaning, the corresponding panel can be removed for processing. The vertical arrangement of the guide channel 33 reduces the lateral span of the fluid transmission path and avoids flow rate attenuation caused by excessively long horizontal channels. The dual-layer microfluidic chip provided by this application is used for rapid processing of saliva samples and efficient sorting of CGRP, reducing labor costs while increasing processing speed.

[0021] The mixing tank is a functional unit used to mix saliva samples with diluent. This structure physically isolates the sample from the pretreatment process to prevent contamination of the separation step. The separation tank is a spiral flow channel system used to separate the target components in the mixture. This design utilizes centrifugal force differences to achieve component separation. The fixed module 3 refers to the positioning frame that supports the upper and lower panels 2. The flow channel 33 is a vertical transport path connecting the upper and lower fluid layers, which can be achieved by setting through-holes inside the module. This channel ensures that the mixture can accurately flow into the lower separation unit.

[0022] In some possible embodiments, the mixing tank includes: a saliva inlet 11, a diluent inlet 12, a saliva inlet channel 13, a diluent inlet channel 14, and a serpentine mixing channel 15; the saliva inlet 11 and the diluent inlet 12 are arranged at intervals, the center-line distance between the saliva inlet 11 and the diluent inlet 12 is 4 cm, one end of the saliva inlet 11 is connected to one end of the saliva inlet channel 13, one end of the diluent inlet 12 is connected to one end of the diluent inlet channel 14, the other ends of the saliva inlet channel 13 and the diluent inlet channel 14 converge to the inlet end of the serpentine mixing channel 15, and a through hole 17 is provided on the bottom wall of the outlet end of the serpentine mixing channel 15.

[0023] Specifically, the saliva inlet 11 and the diluent inlet 12 are spatially independent to avoid cross-contamination during liquid input. The structure consisting of the saliva inlet 11 and the saliva inlet channel 13 is symmetrically distributed on both sides of the front end of the serpentine mixing channel 15, as is the structure consisting of the diluent inlet 12 and the diluent inlet channel 14, ensuring that their fluid paths are identical. The spaced inlets guide the saliva and diluent to the inlet of the serpentine mixing channel 15 through independent channels, keeping the two liquids separate before confluence to ensure a controllable mixing ratio. The serpentine mixing channel 15 uses a continuously bent structure to increase the mixing contact area and time. A through-hole 17 is located on the bottom wall at the end of the mixing channel, allowing the mixed liquid to directly enter the lower processing module, avoiding residue caused by horizontal transfer.

[0024] like Figure 3 As shown, the saliva injection channel 13 and the diluent injection channel 14 are formed by two bent channels connected together. The serpentine mixing channel 15 is formed by eight transverse channels, eight arc-shaped channels and two longitudinal channels connected together. Adjacent transverse channels are connected by a bent channel. The two longitudinal channels are located on both sides of the transverse channels and are connected to an adjacent transverse channel.

[0025] In some possible implementations, the serpentine mixing channel 15 has four bends. With four bends, eight directional changes occur within the channel path. The specific bend angles and spacing can be determined through computational fluid dynamics simulations, allowing the fluid to undergo a specific number of shearing actions within a limited space. When saliva and diluent enter the serpentine mixing channel 15, the fluid undergoes a sudden change in direction at the bends, generating a lateral velocity component. This change in flow state promotes staggered shearing between different fluid layers, accelerating the molecular diffusion process. The optimized number of bends ensures sufficient residence time for the fluid within the channel to complete the mixing reaction while avoiding a surge in flow resistance due to excessive bends. Through four directional changes, the fluid interface is repeatedly stretched and folded, forming a microscopic vortex structure, allowing the CGRP in the saliva to fully contact the diluent and reducing local concentration differences.

[0026] Furthermore, a filter membrane 16 is installed at the connection point between the saliva inlet 11 and the saliva inlet channel 13. The filter membrane 16 is a physical filtration medium with a specific pore size, which can be implemented using a polycarbonate membrane or a cellulose membrane, used to intercept solid particles or large molecular impurities in the saliva sample. The connection point refers to the fluid convergence area between the saliva inlet 11 and the saliva inlet channel 13. Specifically, the filter membrane 16 can be fixed to this area through in-mold fitting or bonding processes, so that the saliva sample must pass through the filter membrane 16 before entering the channel, thereby preventing impurities from entering the subsequent mixing process. When the saliva sample is injected from the inlet, the filter membrane 16 directly performs physical filtration on the sample, intercepting impurities such as food residue and cell debris in the saliva, allowing only the target components and small molecules to pass through. The filtered sample directly enters the saliva inlet channel 13, avoiding interference from impurities in the subsequent mixing and detection process. The integrated design of the filter membrane 16 and the inlet allows the filtration operation to be completed simultaneously with the sample input, without the need for additional pretreatment steps.

[0027] In some possible implementations, the separation tank includes: a mixing liquid inlet 21, a spiral separation channel 22, a straight channel 23, an inner edge groove 24, and an outer edge groove 25; the mixing liquid inlet 21 is located at the central end of the spiral separation channel 22 and is connected to the spiral separation channel; the outer end of the spiral separation channel 22 is connected to one end of the straight channel 23; the other end of the straight channel 23 extends radially to form an asymmetrical inner edge groove 24 and an outer edge groove 25; the inner edge groove 24 and the outer edge groove 25 are independent of each other; the flow channel cross-sections of the inner edge groove 24 and the outer edge groove 25 are both gradually widening; and the straight channel 23 is arranged along the tangential direction of the outer end.

[0028] Among them, the spiral separation channel 22 is a fluid channel with a spiral structure, which achieves the separation of substances of different densities by the difference in centrifugal force generated by the fluid in the spiral path. The gradually widening structure is the shape of the channel cross-section gradually increasing along the flow direction. The asymmetric inner edge slot 24 and outer edge slot 25 refer to the differences between them in the channel width, length or expansion angle, which can be achieved by adjusting the slot geometric parameters to adapt to the differences in physical properties of different components.

[0029] Specifically, when the mixed liquid enters the spiral separation channel 22 from the central end, the centrifugal force causes the heavier components to migrate outwards, while the lighter components concentrate inwards. After flowing to the outer end, the fluid enters the straight channel 23 tangentially, maintaining its original flow inertia to avoid turbulence interference. The separated components enter the gradually widening slot region, where the flow velocity decreases, causing the lighter and heavier components to stably accumulate in the inner edge slot 24 and outer edge slot 25, respectively. Because the inner and outer slots are independent and asymmetrical, different components can be discharged independently along their respective channels, avoiding secondary mixing.

[0030] In some possible implementations, the spiral separation channel 22 has 5 spiral turns.

[0031] Specifically, the spiral separation channel 22 utilizes centrifugal force to cause particles of different densities or sizes to migrate and separate in the fluid. The number of spiral turns directly affects the flow path length and centrifugal force duration within the channel. Setting the number of spiral turns to 5 means that the spiral separation channel 22 completes 5 full rotations. This can be achieved by adjusting the relative positions of the starting and ending points of the spiral. This number of turns ensures sufficient migration and separation of the target particles while avoiding excessive fluid resistance that could lead to high flow rates, thus compressing the total passage time of the fluid during the separation process to within the threshold range required for immediate detection.

[0032] In some possible implementations, the saliva inlet 11, the diluent inlet 12, and the mixing liquid inlet 21 are all circular groove structures, and the diameters of the saliva inlet 11 and the diluent inlet 12 are both twice the diameter of the mixing liquid inlet 21.

[0033] Specifically, the symmetrical nature of the circular groove structure allows saliva and diluent to flow in a laminar state at the inlet, avoiding turbulent interference caused by structural abrupt changes. The larger diameters of the saliva inlet 11 and diluent inlet 12 can accommodate more initial samples; for example, the diameter can be twice that of the mixing liquid inlet 21, ensuring a continuous supply of the two liquids before mixing. The diameters of the saliva inlet 11 and diluent inlet 12 can be set to 2.6 cm, and the diameter of the mixing liquid inlet 21 can be set to 1.3 cm.

[0034] In some possible implementations, the maximum width of the outer edge slot 25 is greater than the maximum width of the inner edge slot 24, and the widths of the outer edge slot 25 and the inner edge slot 24 gradually increase along the flow direction to slow down the flow velocity and enhance the enrichment of the target component. The channel width of the serpentine mixing channel 15 is smaller than the channel width of the spiral separation channel 22, so as to expand the cross-sectional area of ​​the flow channel through the spiral separation channel 22, prolong the fluid residence time, and enhance the centrifugal separation effect. Specifically, the channel width of the serpentine mixing channel 15 can be set to 2.5 cm, and the channel width of the spiral separation channel 22 can be set to 3 cm.

[0035] Specifically, the width and height of the first accommodating cavity 31 are adapted to the width and height of the upper panel 1, while the depth of the first accommodating cavity 31 can be less than or equal to the length of the upper panel 1, as long as it can stably limit the position of the upper panel 1. Similarly, the width and height of the second accommodating cavity 32 are preferably adapted to the width and height of the lower panel 2, while the depth of the second accommodating cavity 32 can be less than or equal to the length of the lower panel 2, as long as it can stably limit the position of the lower panel 2.

[0036] The appendices provided in this application Figure 1 and attached Figure 2 Since the size of the first accommodating cavity 31 is perfectly matched with the size of the upper panel 1, and the size of the second accommodating cavity 32 is perfectly matched with the size of the lower panel 2, it can be understood that in the fixed module 3, in the horizontal direction, the first accommodating cavity 31 is located above and to the side of the second accommodating cavity 32.

[0037] The upper panel 1 and the first accommodating cavity 31, as well as the lower panel 2 and the second accommodating cavity 32, can be directly contacted for positioning, or the panels can be stably positioned by setting a press-type self-locking release mechanism or a snap-fit ​​structure within the fixed module 3. This part can be implemented using existing technology according to specific requirements.

[0038] The specific implementation process of this application is as follows: the lower panel 2 is placed into the second accommodating cavity 32, and saliva and diluent are injected into the upper panel 1 at a precisely controlled flow rate, that is, saliva is injected into the saliva inlet 11 and diluent is injected into the diluent inlet 12. The injection time can be set according to the actual situation, and generally they are injected simultaneously. Then, the upper panel 1 with the injected diluent and saliva is placed into the second accommodating cavity 32. When the saliva passes through the filter membrane 16, large molecules and particles are intercepted, and the sample is initially purified. The filtered saliva and diluent enter the serpentine mixing channel 15, and through its meandering path design, they are fully mixed to form a uniform mixture. The mixture flows through the through hole 17 of the upper panel 1 and the guide channel 33 into the mixing inlet 21 of the lower panel 2, and enters the separation stage. The lower panel 2 is designed with 5 rotating spiral channels, which use the combined effect of inertial force and Dean force to separate particles of different sizes. After the mixed liquid is separated by the spiral separation channel 22, the smaller CGRP particles gather towards the inside of the channel under the action of Dean force and eventually enter the inner edge slot 24; while other larger substances flow along the outside and eventually enter the outer edge slot 25.

[0039] After use, the upper panel 1 and the lower panel 2 can be removed for cleaning in order to facilitate subsequent use.

[0040] Finally, it should be noted that the above embodiments are merely specific implementations of this utility model, used to illustrate the technical solution of this utility model, and not to limit it. The protection scope of this utility model is not limited thereto. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this utility model; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model. All should be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

[0041] Although the embodiments of this utility model have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this utility model. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this utility model is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A dual-layer microfluidic chip, characterized in that, The dual-layer microfluidic chip includes: The assembly comprises an upper panel, a lower panel, and a fixing module. The upper surface of the upper panel has a mixing tank, with a through hole at the bottom of the outlet end of the mixing tank. The upper surface of the lower panel has a separation tank. The fixing module has a first fixing slot and a second fixing slot on its left and right sides, respectively. The first fixing slot extends horizontally into the fixing module to form a first receiving cavity for accommodating the upper panel, and the second fixing slot extends horizontally into the fixing module to form a second receiving cavity for accommodating the lower panel. A longitudinally arranged guide channel is provided between the bottom of the first receiving cavity and the top of the second receiving cavity. When the upper panel is detachably placed in the first receiving cavity, the through hole corresponds to the position of the guide channel. When the lower panel is detachably placed in the first receiving cavity, the sample inlet of the separation tank is located below the guide channel.

2. The dual-layer microfluidic chip as described in claim 1, characterized in that, The mixing tank includes: a saliva inlet, a diluent inlet, a saliva inlet channel, a diluent inlet channel, and a serpentine mixing channel; the saliva inlet and the diluent inlet are arranged at intervals, the center-line distance between the saliva inlet and the diluent inlet is 4 cm, one end of the saliva inlet is connected to the saliva inlet channel, one end of the diluent inlet is connected to the diluent inlet channel, the other ends of the saliva inlet channel and the diluent inlet channel converge to the inlet end of the serpentine mixing channel, and the bottom wall of the outlet end of the serpentine mixing channel is provided with the through hole.

3. The dual-layer microfluidic chip as described in claim 2, characterized in that, The serpentine mixing channel has 4 bends.

4. The dual-layer microfluidic chip as described in claim 2, characterized in that, A filter membrane is provided at the connection between the saliva inlet and the saliva inlet channel.

5. The dual-layer microfluidic chip as described in claim 2, characterized in that, The separation tank includes: a mixing liquid inlet, a spiral separation channel, a straight channel, an inner edge groove, and an outer edge groove; the mixing liquid inlet is located at the central end of the spiral separation channel and is connected to the spiral separation channel; the outer end of the spiral separation channel is connected to one end of the straight channel; the other end of the straight channel extends radially to form an asymmetrical inner edge groove and an outer edge groove; the inner edge groove and the outer edge groove are independent of each other; the flow channel cross-section of the inner edge groove and the outer edge groove is gradually widening; the straight channel is arranged along the tangential direction of the outer edge end.

6. The dual-layer microfluidic chip as described in claim 5, characterized in that, The spiral separation channel has 5 spiral turns.

7. The dual-layer microfluidic chip as described in claim 6, characterized in that, The saliva inlet, the diluent inlet, and the mixing liquid inlet are all circular groove structures, and the diameters of the saliva inlet and the diluent inlet are twice the diameter of the mixing liquid inlet.

8. The dual-layer microfluidic chip as described in claim 7, characterized in that, The maximum width of the outer edge groove is greater than the maximum width of the inner edge groove, and the channel width of the serpentine mixing channel is less than the channel width of the spiral separation channel.

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