Composite microfluidic channel structure for micro-biological sample processing and application thereof

Abstract

The application provides a composite micro-fluid channel structure for micro-biological sample treatment and application thereof, which comprises an upper substrate and a lower substrate, the upper substrate and the lower substrate are attached to each other, a main channel is arranged between the upper substrate and the lower substrate, the two ends of the main channel along the liquid flow direction are respectively connected with a sample inlet area and a waste liquid area, a passive water absorption part is arranged in the waste liquid area, lateral height retreat areas are arranged on the two sides of the main channel along the length direction of the main channel, the lateral height retreat areas have an equivalent fluid height which is greater than the height of the main channel, so that a capillary liquid stop interface is formed between the main channel and the lateral height retreat areas, liquid flows through the main channel and enters the waste liquid area through the capillary suction in the main channel and the water absorption effect of the passive water absorption part. Through the cooperative design of the capillary liquid stop interface formed by the lateral height retreat area and the passive water absorption part in the waste liquid area, stable restriction and self-driving of micro-liquid are realized.

Description

Technical Field

[0001] This invention belongs to the field of microfluidic chip technology, and specifically relates to a composite microfluidic channel structure for processing micro-volume biological samples and its application. Background Technology

[0002] Microfluidics technology is widely used in in vitro diagnostics, biological detection, and timely examination due to its advantages such as small sample consumption, fast response speed, and ease of integration and automation.

[0003] Existing microfluidic chips typically employ a closed-channel structure, driving liquid flow through an external syringe pump, negative pressure device, or centrifugation. However, when processing biological samples such as serum, plasma, and whole blood, especially micro-samples with volumes of only a few microliters, these driving methods suffer from problems such as complex equipment, high cost, and inconvenience for portable and home testing. Furthermore, they are prone to phenomena such as red blood cell adhesion, aggregation, and channel blockage, affecting the stability and repeatability of the test.

[0004] With the development of point-of-care and home-based testing, non-invasive micro-volume body fluid samples such as tears, saliva, and nasal or pharyngeal swab extracts are gradually becoming important testing targets. These samples are typically characterized by extremely small volume, high surface tension, and large viscosity variations, which can easily lead to problems such as unstable spreading, uncontrollable lateral diffusion, and insufficient rinsing efficiency in existing microfluidic structures.

[0005] Therefore, there is an urgent need for a microfluidic channel structure and processing method that requires no external power, has a simple structure, and is universally adaptable to a variety of micro-samples, so as to achieve stable residence of samples in the main channel, controlled flushing, and reliable drainage. Summary of the Invention

[0006] This invention aims to provide a composite microfluidic channel structure for the processing of trace biological samples and its application. It provides a microfluidic channel structure and processing method that is simple in structure, requires no external pump drive, can stably restrict trace amounts of multiple samples, and allows for controllable flushing and reliable drainage, thereby solving the problems existing in the prior art.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: a composite microfluidic channel structure for processing trace biological samples includes an upper substrate and a lower substrate, which are bonded together. A main channel is provided between the upper and lower substrates. The two ends of the main channel along the liquid flow direction are respectively connected to a sample inlet area and a waste liquid area. A passive water absorption element is provided in the waste liquid area. Lateral height relief areas are provided on both sides of the main channel along its length direction. The lateral height relief areas have an equivalent fluid height greater than the height of the main channel, so that a capillary liquid-stopping interface is formed between the main channel and the lateral height relief areas. The liquid flows through the main channel and enters the waste liquid area through the capillary suction in the main channel and the water absorption effect of the passive water absorption element.

[0008] In one embodiment of the present invention, a liquid blocking mechanism is provided at the end of the main channel near the waste liquid area, and the liquid blocking mechanism controls the opening and closing of the flow path of liquid in the main channel to the waste liquid area.

[0009] In one embodiment of the present invention, the liquid blocking mechanism includes magnetic particles disposed at the end of the main channel. The magnetic particles are subjected to magnetic force by an external magnetic field to enhance the liquid blocking strength. The liquid is allowed to flow by releasing the magnetic force or dragging the magnetic particles away.

[0010] In one embodiment of the present invention, the main channel is a low-height capillary channel formed by the groove on the lower surface of the upper substrate and the lower substrate, the height of the main channel is 5-100 micrometers, and the width of the main channel is 0.5-5 millimeters.

[0011] In one embodiment of the present invention, the capillary liquid-stopping interface is formed by the lateral height relief zone in a height abrupt change in the direction perpendicular to the main channel, and the width of the lateral height relief zone is 0.1-10 mm.

[0012] In one embodiment of the present invention, the lateral height relief area is a groove, step, recess, hollow area, or a combination thereof disposed between the upper substrate and the lower substrate.

[0013] In one embodiment of the present invention, the lower substrate surface corresponding to the lateral height relief area is lower than the lower substrate surface corresponding to the main channel, forming a recess with a depth of 20-1000 micrometers. The lateral height relief area corresponds to a deepened groove or a through-hole open structure in the upper substrate.

[0014] In one embodiment of the present invention, the passive absorbent is made of a hydrophilic porous material selected from polyvinyl alcohol, cellulose, polyacrylic acid hydrosols, porous polymers, or combinations thereof.

[0015] In one embodiment of the invention, the inner surface of the main channel is pre-coated with a functional coating, the functional coating comprising an anticoagulant and an anti-nonspecific adsorption material.

[0016] On the other hand, a method for processing trace biological samples using the above-mentioned microfluidic channel structure is provided, the method comprising the following steps: S1. Add 1-20 microliters of microbial sample into the main channel through the sample injection area; S2. The sample is stably confined within the main channel to react using the capillary anti-liquid interface; S3. Add rinsing solution to the sample injection area; S4. Driven by the passive water-absorbing component, the rinsing fluid flows through the main channel to rinse the sample; S5. The rinsed waste liquid is transported to the waste liquid area and absorbed by the passive water absorption element.

[0017] The composite microfluidic channel structure for micro-volume biological sample processing obtained through the above technical solution and its application have the following beneficial effects: 1. Passive drive: Through the collaborative design of "the lateral height relief zone forming a capillary liquid-stopping interface" and "the passive water absorption component in the waste liquid zone", stable confinement and autonomous drive of trace liquids are achieved, completely eliminating the need for complex external pump and valve systems, and greatly reducing cost and size.

[0018] 2. High sample versatility: The unique capillary liquid-stopping design of the lateral height relief zone can effectively restrain trace samples with different viscosities and surface tensions, such as serum, whole blood, saliva, and tears, preventing them from spreading uncontrollably.

[0019] 3. Simple and reliable operation: Only two steps are required: "adding sample" and "adding rinsing solution". The subsequent reaction, rinsing and drainage processes are all completed automatically by the chip structure. The process is standardized, highly repeatable, and suitable for ordinary home users.

[0020] 4. High degree of functional integration: The liquid blocking mechanism provides active control over the reaction time, further improving the accuracy and flexibility of detection. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the composite microfluidic channel structure for micro-volume biological sample processing described in this invention; Figure 2 This is a schematic diagram of another embodiment of the composite microfluidic channel structure for micro-volume biological sample processing described in this invention; Figure 3 This is a schematic diagram of the structure of the lower substrate described in this invention; Figure 4 This is a schematic diagram of the structure of the upper substrate described in this invention; Figure 5 This is a schematic diagram of another embodiment of the substrate described in this invention; Figure 6 This is a cross-sectional view of the composite microfluidic channel structure for micro-volume biological sample processing described in this invention; Figure 7 This is a cross-sectional view of another embodiment of the composite microfluidic channel structure for micro-volume biological sample processing described in this invention; Figure 8 This invention is in Figure 1 A schematic diagram of the principle of microfluidic channel for sample drop; Figure 9 This is the present invention. Figure 8 A schematic diagram of the principle of adding rinsing fluid through a microfluidic channel; Figure 10 This invention is in Figure 2 A schematic diagram of the principle of microfluidic channel for sample drop; Figure 11 This is the present invention. Figure 10 A schematic diagram of the principle of adding rinsing fluid through a microfluidic channel.

[0022] In the diagram, 1 is the upper substrate; 2 is the lower substrate; 3 is the main channel; 4 is the sample injection area; 5 is the waste liquid area; 6 is the lateral height relief area; 7 is the liquid blocking mechanism; 8 is the passive water absorption component; and 9 is the sample dispensing hole. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0024] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0025] This invention relates to the field of microfluidic chip technology, specifically to a composite microfluidic channel structure for processing micro-volume biological samples and its application. By creating a "capillary anti-liquid interface" between the main channel and the lateral region, the capillary force in the lateral region is much weaker than that in the main channel because the capillary force is inversely proportional to the channel height. This effectively prevents the liquid from diffusing to both sides and stably confines the sample within the narrow and deep main channel.

[0026] The present invention will be further explained and described below with reference to the embodiments and accompanying drawings. It should be understood that the present invention is not limited to the specific embodiments described.

[0027] like Figure 1 , Figure 6 As shown, this invention proposes a composite microfluidic channel structure for processing trace biological samples, including an upper substrate 1 and a lower substrate 2. The upper substrate 1 and the lower substrate 2 are bonded together, and a main channel 3 is provided between the upper substrate 1 and the lower substrate 2. The two ends of the main channel 3 along the liquid flow direction are respectively connected to a sample inlet area 4 and a waste liquid area 5. A passive water absorption element 8 is provided in the waste liquid area 5. Lateral height relief areas 6 are provided on both sides of the main channel 3 along its length direction. The lateral height relief areas 6 have an equivalent fluid height greater than the height of the main channel, so that a capillary liquid-stopping interface is formed between the main channel 3 and the lateral height relief areas 6. The liquid flows through the main channel 3 and enters the waste liquid area 5 through the capillary suction in the main channel 3 and the water absorption effect of the passive water absorption element 8.

[0028] Capillary force is key to driving liquids forward in microchannels. For a simple rectangular hydrophilic channel, the magnitude of the capillary force (ΔP) is inversely proportional to the channel height (H): ΔP∝1 / H.

[0029] Therefore, the smaller the value of H, the greater the capillary force, and the easier it is for the liquid to be "drawn in". Thus, a lateral height relief zone 6 with an equivalent fluid height greater than the main channel height is set up next to the main channel 3. When the liquid enters the main channel, the strong capillary force drives the liquid to quickly fill this narrow space. However, when the liquid front reaches the junction of the main channel 3 and the lateral height relief zone 6, the capillary force in the lateral height relief zone 6 weakens sharply (due to the sudden increase in height). The liquid experiences a "forward" (along the main channel direction) traction force at this point. This force forms a stable liquid meniscus boundary (i.e., a capillary stop interface) at the junction, preventing the liquid from easily crossing this boundary and spreading laterally.

[0030] The principle of microfluidic channel structure for processing micro-volume biological samples is as follows: Figure 8 , Figure 9 As shown: A. Add 1-20 microliters of microbial sample to the main channel through the sample injection area; B. Allow the trace biological sample to remain in the main channel for 1-5 minutes; C. Add rinsing solution from the sample injection area; D. Under the action of capillary force and passive suction components, the flushing liquid flows through the main channel, and the waste liquid is discharged to the waste liquid area where it is absorbed by the passive suction components.

[0031] Among them, the trace biological sample is a biologically derived liquid sample with a volume of no more than 50 microliters, preferably 2- 10 microliters, including but not limited to serum, plasma, whole blood, tears, nasal or pharyngeal swab extracts, urine, cerebrospinal fluid or dilutions thereof.

[0032] The rinsing solution may contain a low concentration of surfactant to reduce sample viscosity and inhibit cell or particle aggregation.

[0033] Preferably, the waste liquid area is circular or elliptical, and the outer perimeter of the waste liquid area, where it meets the main channel, naturally forms an arc shape according to the shape of the waste liquid area, so that the liquid can easily spread evenly after flowing in.

[0034] like Figure 2 As shown, as a further improvement of the present invention, a liquid blocking mechanism 7 is provided at the end of the main channel 3 near the waste liquid area 5. The liquid blocking mechanism 7 controls the opening and closing of the flow path of liquid in the main channel 3 to the waste liquid area 5.

[0035] Preferably, the liquid blocking mechanism 7 includes magnetic particles disposed at the end of the main channel. An external magnetic field applies magnetic force to the magnetic particles to enhance liquid blocking strength. Liquid flow is allowed by releasing the magnetic force or dragging the magnetic particles away. When precise control of the reaction time is required, the end of the channel is temporarily blocked with magnetic particles, and the magnetic particles are fixed by a magnetic field (external magnet) to enhance liquid blocking. The liquid flow is released by removing the magnet or dragging the magnetic particles away.

[0036] The magnetic particles can be spherical or cubic, and the side length of the cubic magnetic particles is greater than or equal to the width of the main channel 3, so as to cover the main channel 3.

[0037] As a further improvement of the present invention, the sample injection area 4 is a sample feeding hole provided on the substrate, and the sample feeding hole is connected to the main channel 3.

[0038] As a further improvement of the present invention, the upper substrate is also provided with a sample loading hole 9, which is connected to the main channel 3 and is located between the sample injection area and the liquid blocking mechanism 7.

[0039] The principle of another implementation method for microfluidic channel structures in the processing of micro-volume biological samples is as follows: Figure 10 , Figure 11 As shown: A. Add the sample through the sample loading well; B. At this time, the sample flows bidirectionally in the main channel under the action of capillary force, and the sample flowing towards the waste liquid area is intercepted by the liquid blocking mechanism; C. After the reaction is complete, remove the liquid blocking mechanism and add rinsing solution through the sample inlet in the injection area; D. Under the action of capillary force and passive suction components, the flushing liquid flows through the main channel, and the waste liquid is discharged to the waste liquid area where it is absorbed by the passive suction components.

[0040] As a further improvement of the present invention, the main channel 3 is a low-height capillary channel formed by the groove provided on the lower surface of the upper substrate 1 and the lower substrate 1. The height of the main channel 3 is 5-100 micrometers and the width of the main channel 3 is 0.5-5 millimeters.

[0041] Preferably, the height of the main channel 3 is 10-60 micrometers, more preferably 20-40 micrometers.

[0042] As a further improvement of the present invention, the capillary liquid-stopping interface is formed by a sudden height change in the lateral height relief zone 6 in the direction perpendicular to the main channel 3, and the width of the lateral height relief zone 6 is 0.1-10 mm. The height of the lateral height relief zone 6 is significantly greater than the height of the main channel, forming a sudden height jump, ensuring that the main channel 3 forms a high capillary force.

[0043] Preferably, the width of the lateral height relief zone 6 is 0.3-5 mm.

[0044] More preferably, the lateral height relief area 6 is a groove, step, recessed area, hollow area or a combination thereof provided between the upper substrate 1 and the lower substrate 2.

[0045] like Figures 3-5 As shown, as a further improvement of the present invention, the surface of the lower substrate 2 corresponding to the lateral height relief area 6 is lower than the surface of the lower substrate 2 corresponding to the main channel 3, forming a recess with a depth of 20-1000 micrometers. The lateral height relief area 6 corresponds to a deepened groove in the upper substrate 1. Figure 4 ) or through ( Figure 5 ) open structure.

[0046] like Figure 6 As shown, a deep groove (but not penetrating) is machined on the inner side of the upper substrate. After being bonded to the lower substrate, it forms a lateral chamber with a closed top but a high internal space. Advantages: 1. Sample sealing: The entire liquid remains within the closed system, avoiding evaporation and contamination, making it safer and more reliable. 2. High physical strength: Maintains the integrity of the chip. 3. Still allows for height abrupt changes: As long as the depth of the groove (e.g., 200µm) is much greater than the height of the main channel (e.g., 30µm), it can still effectively form a capillary barrier, preventing liquid from entering.

[0047] like Figure 7 As shown, grooves or holes are directly cut into the upper substrate to form an open structure, allowing the lateral height relief zone 6 to directly communicate with the outside atmosphere. Advantages: 1. Simple processing: For some materials (such as plastics), direct injection molding or cutting out through grooves may be easier than processing grooves of a specific depth. 2. No top wall interference: Completely eliminates the possibility of droplets contacting the upper wall, which is more advantageous for samples that are easily adsorbed or require observation.

[0048] As a further improvement of the present invention, the passive water-absorbing element 8 is made of a hydrophilic porous material.

[0049] Preferably, the hydrophilic porous material is selected from polyvinyl alcohol, cellulose, polyacrylic acid hydrosols, porous polymers, or combinations thereof.

[0050] Preferably, the passive absorbent further comprises polyethylene glycol (PEG) and reinforcing agents such as sucrose or mannitol. PEG is a hydrophilic polymer that can rapidly bind with water, helping water molecules quickly penetrate deep into the pores of the absorbent material and shortening the start-up time. Simultaneously, it can form a more uniform hydrophilic network within the material, providing stable and continuous capillary force. During the drying and curing process of absorbent materials (such as PVA solutions), water evaporation can cause polymer chains to aggregate and shrink, making the pores prone to collapse. Sucrose or mannitol molecules can intersperse between the polymer chains, acting as a "scaffold" or "spacer" to support the structure, ensuring that the dried product is a fluffy, porous, sponge-like solid, rather than a dense, poorly absorbent film.

[0051] A simpler method is to use suitable filter paper or similar absorbent material, cut to a shape that fits tightly against the main channel and fills the waste liquid area, and pre-fill it into the waste liquid area.

[0052] As a further improvement of the present invention, the inner surface of the main channel 3 is pre-coated with a functional coating, the functional coating comprising an anticoagulant and an anti-nonspecific adsorption material.

[0053] The anticoagulant is selected from heparin, EDTA or a combination thereof, and the anti-nonspecific adsorption material is selected from protein blocking agents, preferably bovine serum albumin (BSA).

[0054] When processing whole blood samples, blood contact with foreign objects can activate the coagulation pathway, forming blood clots or causing platelets and red blood cells to aggregate and adhere to the surface. By pre-coating the inner wall of the channel with anticoagulants such as heparin, the coagulation cascade reaction and cell activation can be effectively inhibited, maintaining the liquid fluidity of the blood sample and ensuring that the capillary drive mechanism can operate stably and for a long time as designed.

[0055] Biological samples (especially serum and plasma) contain a large number of various proteins. These proteins can non-specifically and randomly adsorb onto the inner wall of the channel and around potentially pre-positioned capture molecules (such as antibodies and probes). Blocking proteins such as BSA can preemptively occupy the active adsorption sites on the inner wall of the channel, forming an inert, biocompatible interface, which is like laying a "non-stick layer" on the channel. This can minimize non-specific adsorption and ensure that the detection signal mainly comes from specific biological reactions, thereby greatly improving the accuracy, sensitivity and repeatability of the detection.

[0056] Example 1: Stable retention and rinsing of serum samples 1. Channel structure An upper and lower substrate were fabricated using PMMA material, and the two substrates were bonded together to form a microfluidic chip. A linear main channel with a length of 60 mm, a width of 3 mm, and a height of 30 μm was incorporated into the chip. Lateral height relief grooves, parallel to the main channel, were formed in the lower substrate on both sides of the main channel. Each relief groove was 2 mm wide and 50 μm deep. A through-hole structure was incorporated in the upper substrate at corresponding positions, creating a significant vertical height abrupt change on both sides of the main channel.

[0057] 2. Surface treatment The inner wall of the main channel is pre-coated with a buffer solution containing heparin and bovine serum albumin (BSA), which, after drying, forms an anticoagulant and anti-nonspecific adsorption coating.

[0058] 3. Operating Method Add 5 microliters of human serum sample to the inlet of the main channel and let the sample stand in the channel for 3 minutes; Subsequently, 50 μL of PBS diluent containing 0.05% (V / V) Triton X-100 was added from the inlet end. The other end of the main channel was connected to a dry PVA porous absorbent membrane as a waste liquid zone. The diluent passively flowed through the main channel under capillary action and was absorbed by the waste liquid zone.

[0059] 4. Experimental Results During sample retention and rinsing, the serum fluid remained stably confined within the main channel, and no fluid was observed entering the lateral height relief structure; after rinsing, no obvious residual protein precipitation or bubbles were generated in the main channel.

[0060] 5. Technical Effects The results show that the channel structure of the present invention can achieve stable retention and effective rinsing of serum samples in the low-height main channel without the need for external drive.

[0061] Example 2: Passive Driven Processing of Plasma Samples 1. Channel structure The main channel height is 25 micrometers, and the other structural parameters are the same as in Example 1; the lateral height relief groove has a depth of 40 micrometers in the lower substrate, and the upper substrate has a deepened groove structure (non-through).

[0062] 2. Operating Method Add 5 μL of anticoagulated plasma sample to the main channel and let stand for 2 minutes; then add 40 μL of buffer containing 0.03% Triton X-100.

[0063] 3. Experimental Results No significant spreading or lateral leakage occurred in the plasma sample during the residence phase; the liquid interface advanced steadily during rinsing, and the lateral height relief tank remained dry.

[0064] 4. Technical Effects This demonstrates that, under different height combinations and non-penetrating substrate structures, the present invention can still form an effective capillary liquid-stopping interface.

[0065] Example 3: Controlled washing of whole blood samples and inhibition of cell aggregation 1. Channel structure The main channel height is 40 micrometers; the depth of the lateral height relief groove on the lower substrate is 80 micrometers; the upper substrate has a through-type open groove structure.

[0066] 2. Reagent Preparation The inner wall of the main channel is pre-coated with heparin and BSA; PEG is pre-mixed into the PVA membrane in the waste liquid area; the rinsing solution contains 0.02% Triton X-100.

[0067] 3. Operating Method Add 5 μL of whole blood sample to the main channel and let it stand for 3 minutes; then add 60 μL of rinsing solution, which is passively absorbed by the PVA membrane.

[0068] 4. Experimental Results During the residence and rinsing process, no red blood cells showed obvious adhesion or aggregation; the main channel remained unobstructed, and the lateral clearance grooves were not wetted.

[0069] 5. Technical Effects This demonstrates that the structure and reagent combination of the present invention are suitable for the passive processing of small samples with high cell density.

[0070] Example 4: Micro-processing of saliva samples 1. Channel structure The main channel height is 20 micrometers; the lateral height relief groove depth is 30 micrometers; and the upper substrate has a deepened groove.

[0071] 2. Operating Method Add 3 μL of saliva sample to the main channel and let stand for 2 minutes; then add 30 μL of buffer containing 0.05% Triton X-100.

[0072] 3. Experimental Results Saliva samples formed a stable liquid column in the main channel without lateral diffusion; no obvious residual mucus was found in the main channel after rinsing.

[0073] 4. Technical Effects This invention demonstrates that the structure is suitable for use with high surface tension and low volume liquid samples.

[0074] Example 5: Processing of tear samples 1. Operating Method Add 2 μL of artificial tear sample to the main channel and let it sit for 2 minutes; then add 30 μL of rinsing solution, which is absorbed by the PVA membrane at the waste end.

[0075] 2. Experimental Results Tear samples can remain stable in the low-height main channel, and the rinsing process is controllable.

[0076] 3. Technical Effects This invention is verified to be applicable to extremely small volumes of body fluid samples.

[0077] Example 6: Preparation of a passive water absorption component for the waste liquid zone in a microfluidic terminal 1. Preparation of water-absorbing material solution Weigh the following components, add them to deionized water, and stir thoroughly until completely dissolved: Polyvinyl alcohol (PVA) 5-10%; Polyethylene glycol (PEG); Deionized water.

[0078] 2. Laying the absorbent structural membrane The above solution is spread evenly in the waste liquid area at the end of the microfluidic channel. The waste liquid area is approximately 2cm x 2cm x 0cm in size, and the thickness of the absorbent film after spreading is controlled to not exceed the height of the waste liquid area.

[0079] The chip coated with absorbent water is dried using methods such as hot air drying, natural air drying, or vacuum drying. After drying, a dry absorbent layer is formed in the waste liquid area, which exhibits a porous or quasi-porous morphology in its microstructure.

[0080] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof embody the principles of the present invention and fall within the protection scope of the present invention.

[0081] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0082] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0083] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A composite microfluidic channel structure for processing trace biological samples, comprising an upper substrate (1) and a lower substrate (2), wherein the upper substrate (1) and the lower substrate (2) are bonded together, a main channel (3) is provided between the upper substrate (1) and the lower substrate (2), the two ends of the main channel (3) along the liquid flow direction are respectively connected to a sample injection area (4) and a waste liquid area (5), and a passive water absorption element (8) is provided in the waste liquid area (5), characterized in that, The main channel (3) has lateral height relief zones (6) on both sides along its length direction. The lateral height relief zones (6) have an equivalent fluid height greater than the height of the main channel (3), so that a capillary liquid-stopping interface is formed between the main channel (3) and the lateral height relief zones (6). The liquid flows through the main channel (3) and enters the waste liquid zone (5) through the capillary suction in the main channel (3) and the water absorption effect of the passive water absorption element (8).

2. The composite microfluidic channel structure for micro-volume biological sample processing according to claim 1, characterized in that, A liquid blocking mechanism (7) is provided at the end of the main channel (3) near the waste liquid area (5). The liquid blocking mechanism (7) controls the opening and closing of the flow path of liquid in the main channel (3) to the waste liquid area (5).

3. The composite microfluidic channel structure for micro-volume biological sample processing according to claim 2, characterized in that, The liquid blocking mechanism (7) includes magnetic particles disposed at the end of the main channel. The magnetic particles are subjected to magnetic force by an external magnetic field to enhance the liquid blocking strength. The liquid is allowed to flow by releasing the magnetic force or dragging the magnetic particles away.

4. The composite microfluidic channel structure for processing micro-volume biological samples according to claim 1, characterized in that, The main channel (3) is a low-height capillary channel formed by the groove on the lower surface of the upper substrate (1) and the lower substrate (1). The height of the main channel (3) is 5-100 micrometers and the width of the main channel (3) is 0.5-5 millimeters.

5. The composite microfluidic channel structure for processing micro-volume biological samples according to claim 1, characterized in that, The capillary liquid-stopping interface is formed by the abrupt change in height of the lateral height relief zone (6) in the direction perpendicular to the main channel (3), and the width of the lateral height relief zone (6) is 0.1-10 mm.

6. The composite microfluidic channel structure for processing micro-volume biological samples according to claim 5, characterized in that, The lateral height relief area (6) is a groove, step, recessed area, hollow area or a combination thereof provided between the upper substrate (1) and the lower substrate (2).

7. The composite microfluidic channel structure for micro-volume biological sample processing according to claim 5, characterized in that, The surface of the lower substrate (2) corresponding to the lateral height relief area (6) is lower than the surface of the lower substrate (2) corresponding to the main channel (3), forming a depression with a depth of 20-1000 micrometers. The lateral height relief area (6) in the upper substrate (1) is a deepened groove or a through open structure.

8. The composite microfluidic channel structure for micro-volume biological sample processing according to claim 1, characterized in that, The passive water-absorbing component (8) is made of a hydrophilic porous material selected from polyvinyl alcohol, cellulose, polyacrylic acid hydrosol, porous polymer or a combination thereof.

9. The composite microfluidic channel structure for processing micro-volume biological samples according to claim 1, characterized in that, The inner surface of the main channel (3) is pre-coated with a functional coating, which includes an anticoagulant and an anti-nonspecific adsorption material.

10. An application for processing trace biological samples, characterized in that, The detection using the microchannel structure of any one of claims 1-9 includes at least the following steps: S1. Add 1-20 microliters of microbial sample into the main channel through the sample injection area; S2. The sample is stably confined within the main channel to react using the capillary anti-liquid interface; S3. Add rinsing solution to the sample injection area; S4. Driven by the passive water-absorbing component, the rinsing fluid flows through the main channel to rinse the sample; S5. The rinsed waste liquid is transported to the waste liquid area and absorbed by the passive water absorption element.

Images