Chip for enriching and dispersing magnetic beads and operation method thereof

Abstract

The invention provides a chip for enriching and dispersing magnetic beads and an operation method thereof. The chip comprises a sample inlet, an enrichment magnetic bead functional area and a discrete magnetic bead functional area which are communicated in sequence. The sample inlet is used for introducing a fluid reagent containing magnetic beads; the enriched magnetic bead functional area is matched with a magnetic part which is movably arranged in the flowing direction of the fluid reagent, the enriched magnetic beads are attracted through magnetic force, and the enriched magnetic beads are driven to move in the flowing direction; the discrete magnetic bead functional area is used for connecting and dispersing the enriched magnetic beads; the discrete magnetic bead functional area is provided with a plurality of discrete units, and the width of the cross section of a flow channel of each discrete unit has a change trend of first decreasing and then increasing in the flowing direction. The operation method of the chip for enriching and dispersing the magnetic beads is mainly based on the structural design and the functional module of the chip, and comprises the following steps of: performing corresponding flowing, uniform mixing, reaction and the like on a biochemical reagent in the chip for enriching and dispersing the magnetic beads through driving of pressure control, magnetic force control, mechanical movement and the like of an instrument; and obtaining a detection result.

Description

Technical Field

[0001] This application relates to the field of microfluidics, and in particular to a chip for enriching and dispersing magnetic beads and a method for operating the same. Background Technology

[0002] Single-molecule immunoassay is an ultra-sensitive protein detection technique that involves dispersing and counting analyte molecules into a large number of independent reaction units (such as droplets). This technique typically comprises three core steps: sample processing and the immunoreaction of reagents, the monodispersion of magnetic beads and immunoreaction complexes, and the detection of fluorescence signals. Among these, the monodispersion of magnetic beads is crucial for achieving high-sensitivity digital detection. Currently, techniques for achieving monodispersion of magnetic beads, besides bead placement and bead spreading, include flow-focusing droplet encapsulation. This involves using a microfluidic chip to merge an aqueous phase containing magnetic beads with an oil phase at a flow-focusing node, generating water-in-oil droplets, thus encapsulating the magnetic beads within discrete droplets. However, this method is limited by the inherent physical statistical law of the Poisson distribution. During droplet formation, magnetic beads randomly enter the droplets, resulting in a large number of empty droplets, a small number of single-bead droplets, and a certain number of multi-bead droplets within the droplet population.

[0003] When using the flow focusing droplet encapsulation method for testing, existing techniques typically employ two strategies to obtain a sufficient number of individually wrapped magnetic bead droplets for effective statistical analysis: First, maintaining a constant magnetic bead concentration while significantly increasing the total droplet volume, which leads to a substantial increase in detection time, reagent consumption, and instrument costs; second, increasing the magnetic bead concentration to enhance the absolute number of individually wrapped magnetic bead droplets, but this drastically increases the proportion of multi-bead droplets, and high-concentration magnetic beads are prone to aggregation and sedimentation, leading to microchannel blockage and experimental failure.

[0004] Therefore, how to effectively increase the number of droplets per pack of magnetic beads without significantly increasing the total droplet volume and without causing magnetic bead agglomeration and blockage is a question that those skilled in the art need to consider. Summary of the Invention

[0005] To address the problems in the prior art, this application provides a chip for enriching and dispersing magnetic beads and a method for operating the same.

[0006] This application provides a chip for enriching and dispersing magnetic beads, comprising an inlet, an enrichment magnetic bead functional area, and a dispersion magnetic bead functional area. The inlet is used to introduce a fluid reagent containing magnetic beads. The enrichment magnetic bead functional area is connected to the inlet and is used to cooperate with a magnetic component movably disposed along the flow direction of the fluid reagent. The magnetic component attracts the enriched magnetic beads and drives the enriched magnetic beads to move along the flow direction. The dispersion magnetic bead functional area is connected to the enrichment magnetic bead functional area and is used to receive and disperse the enriched magnetic beads. The dispersion magnetic bead functional area has several discrete units, and the cross-sectional width of the flow channel of each discrete unit has a decreasing-then-increasing trend along the flow direction.

[0007] Understandably, by setting up enrichment and dispersion bead functional areas, a two-step operation of "enrichment followed by dispersion" of magnetic beads is achieved within the chip. First, the movable magnetic component can form a locally high-concentration magnetic bead suspension within the enrichment bead functional area without changing the initial sample concentration, thus creating conditions for the subsequent generation of a large number of droplets containing individual magnetic beads. Second, the subsequent dispersion bead functional area guides the fluid to impact the magnetic bead agglomerates through changes in the flow channel cross-section, solving the problem of magnetic bead agglomeration and adhesion that inevitably occurs due to magnetic field enrichment, and avoiding the risk of blockage caused by magnetic bead agglomerates directly entering the downstream microchannels. This solves the dilemma in the background technology where increasing the magnetic bead concentration leads to agglomeration and blockage, while not increasing the concentration results in low yield per droplet. It effectively increases the absolute number and proportion of single-pack magnetic bead droplets within a limited total droplet volume, achieving a dual improvement in detection efficiency and accuracy.

[0008] In one embodiment, the discrete unit includes an acceleration section, a transition section, and a deceleration section arranged sequentially along the flow direction, with the transition section connecting the acceleration section and the deceleration section. The cross-sectional width of the flow channel in the acceleration section gradually decreases along the flow direction, while the cross-sectional width of the flow channel in the deceleration section gradually increases along the flow direction. The two ends of the transition section along the flow direction are respectively connected to the minimum cross-sectional width of the flow channel in the acceleration section and the minimum cross-sectional width of the flow channel in the deceleration section.

[0009] Understandably, by specifying the discrete unit into acceleration, transition, and deceleration sections, the fluid carrying the magnetic bead agglomerates gradually increases in velocity during the acceleration section, reaching a peak velocity in the narrowest transition section, and then experiences a sharp drop in velocity during the deceleration section. This drastic cycle of velocity increases and decreases subjectes the magnetic bead agglomerates to strong fluid shear and inertial forces, effectively separating the magnetic beads that are aggregated by magnetic or van der Waals forces. This significantly improves the discreteness and monodispersity of the magnetic beads, ensuring a high proportion of individually packed magnetic bead droplets.

[0010] In one embodiment, the flow channel of the transition section is configured to be straight along the flow direction.

[0011] Understandably, constructing the transition section as a straight line is a simple and easily microfabrication solution. This design simplifies the chip manufacturing process, reduces production costs, and improves chip yield and flow channel stability while ensuring that the fluid can reach maximum velocity to generate effective shear force, thus achieving both cost-effectiveness and reliability.

[0012] In one embodiment, the flow channel of the transition section is configured to be curved along the flow direction and has multiple bends.

[0013] Understandably, compared to a straight transition section, setting up a curved flow channel introduces an additional dispersion mechanism. When magnetic bead agglomerates flow at high speed through the bend, due to inertial effects, larger agglomerates tend to detach from the streamline and collide with the flow channel wall. The combined effects of fluid shearing and physical collision greatly enhance the force on the magnetic bead agglomerates, especially for tightly bound agglomerates, where the dispersion effect is more significant, thereby further improving the yield of individual magnetic beads.

[0014] In one embodiment, the flow channel of the transition section extends in a wavy manner along the flow direction, and the bending angle of the bend relative to the flow direction is 60° to 120°.

[0015] Understandably, the wavy flow channel design causes the magnetic beads to experience multiple, alternating wall collisions during their advancement, achieving a continuous and efficient discretization process. Limiting the bending angle to between 60° and 120° represents an optimized balance between discretization effectiveness and smooth flow: too small an angle results in insufficient collision force and poor discretization; too large an angle may lead to a significant increase in fluid resistance or even blockage of the magnetic beads. This preferred angle range ensures that the magnetic beads can withstand sufficiently strong impact forces for effective separation, while maintaining the stable operation of the entire chip for enriching and discretizing magnetic beads.

[0016] In one embodiment, there are multiple discrete units connected sequentially along the flow direction; each discrete unit includes a transition section, and the cross-sectional width of the flow channel of one transition section is smaller than the cross-sectional width of another transition section located upstream of it along the flow direction.

[0017] Understandably, a hierarchical discretization system was constructed by setting up multiple discrete units. The enriched large magnetic bead agglomerates are initially broken down into smaller agglomerates in the upstream discrete unit, which has a wider flow channel and relatively lower flow velocity. These smaller agglomerates then enter the downstream unit, which has a narrower flow channel and higher flow velocity, for further discretization. This progressive processing method efficiently handles agglomerates of various sizes, avoiding the problem of large agglomerates directly clogging a single extremely narrow channel, thus ensuring greater thoroughness and robustness in the discretization of enriched magnetic beads.

[0018] In one embodiment, the ratio of the maximum to the minimum width of the flow channel cross-section of the discrete unit ranges from 10 to 100.

[0019] Understandably, limiting the ratio to 10 to 100 ensures that sufficiently drastic velocity changes can be generated within the discrete unit. According to fluid dynamics principles, a large aspect ratio means a significant velocity difference between the acceleration and deceleration phases, resulting in extremely strong shear stress. The 10 to 100 ratio range is an experimentally optimized interval that ensures the generated fluid forces are sufficient to overcome the attractive forces between the magnetic beads, achieving efficient discretization, while avoiding problems such as excessively high driving pressure or manufacturing difficulties caused by an excessively large ratio.

[0020] In one embodiment, the flow channel of the acceleration section is an arc shape with a cross-sectional width that gradually decreases along the flow direction, and the flow channel of the deceleration section is an arc shape with a cross-sectional width that gradually increases along the flow direction.

[0021] Understandably, the use of an arc-shaped flow channel design makes the changes in channel width smoother and more continuous, effectively avoiding fluid dead zones or eddies at corners and ensuring a more uniform and stable flow field distribution. This not only reduces the risk of magnetic beads accidentally getting stuck or depositing in the flow channel, but also ensures that each magnetic bead entering the discrete unit undergoes a controllable and consistent acceleration and deceleration process, thereby improving the uniformity and reliability of the discrete process.

[0022] In one embodiment, the magnetic element is movably disposed between a first position and a second position along the flow direction. Both the first and second positions correspond to the enrichment magnetic bead functional areas and are distributed at intervals along the flow direction. A filter column array is also provided at the boundary between the enrichment magnetic bead functional areas and the discrete magnetic bead functional areas. The first position is closer to the injection port than the second position, and the second position is closer to the filter column array than the first position.

[0023] Understandably, this two-stage enrichment design and filter column array setup further optimize the enrichment and dispersion effects. First, placing the magnetic component closer to the inlet shortens the distance between the magnetic component and the magnetic beads flowing out of the inlet, enhancing the magnetic component's attraction to the beads and enabling rapid enrichment of the beads. Then, the magnetic component is moved to a second position closer to the filter column array. The enriched beads, under magnetic traction, follow the magnetic component to the second position closer to the filter column array, preventing them from adhering to the channel walls and failing to enter the dispersion zone during natural flow. This ensures both high efficiency in enrichment and stability in bead flow. Second, while acting as a safety barrier to filter out potentially large impurities, the filter column array also provides initial mechanical dispersing and pre-dispersion of the bead agglomerates about to enter the dispersion zone, reducing the burden on subsequent dispersion units and improving the synergy and efficiency of the entire "enrichment-dispersion" process.

[0024] This application also provides an operation method for a chip for enriching and dispersing magnetic beads, using the chip for enriching and dispersing magnetic beads as described in any of the foregoing embodiments, including the following steps: Step S1: Add an aqueous fluid reagent containing magnetic beads that has undergone an immunoassay to the injection port, and activate the drive to generate droplets at the droplet generation port of the chip for enriching and dispersing magnetic beads. Step S2: Move the magnetic component to a first position close to the injection port and hold it for a certain period of time to enrich the magnetic beads. Move the magnetic component along the flow direction to a second position closer to the discrete magnetic bead functional area than the first position, so as to drive the enriched magnetic beads to move to the discrete magnetic bead functional area. Step S3: Release the magnetic field constraint on the magnetic beads, so that the magnetic beads are driven into the discrete magnetic bead functional area, and accelerate and then decelerate in the discrete unit to achieve dispersion. Step S4: The aqueous fluid containing the magnetic beads enriched in step S2 and dispersed in step S3 mixes with the oil fluid at the droplet generation port to generate several target droplets, some of which contain a magnetic bead. The target droplets enter the droplet collection and detection area. Step S5: Collect droplets within a certain period from the start of target droplet generation to the stop time point in the droplet collection and detection area as detection droplets for detection.

[0025] Understandably, by precisely controlling the position and duration of the magnetic component (step S2) and timely releasing the magnetic field (step S3), this method can actively and controllably generate a high-concentration and monodisperse magnetic bead flow in a flowing system. Simultaneously, combined with the selective interception strategy in step S5, it accurately captures the high-value droplet regions generated by the magnetic bead flow, discarding empty droplets in the low-concentration regions before and after. This allows detection resources to be fully concentrated on the sample with the highest information density, significantly shortening the effective data acquisition time and improving detection throughput and instrument utilization efficiency.

[0026] In one embodiment, the time when the magnetic component moves to the first position in step S2 is t1, the time when the magnetic field constraint is released in step S3 is t2, the time when the target droplet is formed in step S4 is t3, and the time when the target droplet is stopped being captured in step S5 is t4. Specifically, during the time period from t1 to t2, the magnetic bead concentration at the droplet generation port remains essentially constant; during the time period from t2 to t3, the magnetic bead concentration at the droplet generation port first remains essentially constant and then increases, reaching its maximum at t3; during the time period from t3 to t4, the magnetic bead concentration at the droplet generation port gradually decreases; and during the time period from t3 onwards, the rate of decrease in the magnetic bead concentration at the droplet generation port gradually decreases.

[0027] Understandably, this embodiment defines the characteristic curve of the magnetic bead concentration at the droplet generation port as a function of time. This characteristic curve clearly depicts the concentration change trend over time generated by the entire process of "enrichment-dispersion-transport," verifying that the method can generate a magnetic bead flow with significant peaks and predictable morphology. The operator can precisely set the cutoff window from t3 to t4 based on this predictable concentration change pattern, thereby ensuring that the highest quality test samples are obtained in each experiment, improving the accuracy and consistency of the test results. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the chip for enriching and dispersing magnetic beads provided in the embodiments of this application.

[0029] Figure 2 This is a partially enlarged schematic diagram of the area between the sample inlet and the functional region of the enriched and discrete magnetic beads chip provided in this application embodiment.

[0030] Figure 3 This is a partially enlarged schematic diagram of the discrete functional area of ​​a chip for enriching and discrete magnetic beads provided in an embodiment of this application.

[0031] Figure 4 This is a partially enlarged schematic diagram of the discrete functional area of ​​a chip for enriching and discrete magnetic beads provided in another embodiment of this application.

[0032] Figure 5 This is a flowchart illustrating the operation method of the chip for enriching and discrete magnetic beads provided in the embodiments of this application.

[0033] Figure 6 This is a schematic diagram showing the change of magnetic bead concentration at the droplet generation port over time during chip operation of the enriched and discrete magnetic beads provided in this application embodiment.

[0034] Figure 7 This is a physical schematic diagram of the chip used in the embodiments of this application for enriching and dispersing magnetic beads.

[0035] Figure 8 This is a schematic image of the droplet collection and detection area corresponding to the 3rd row and 3rd column in Comparative Example 3 of this application.

[0036] Figure 9 This is a schematic image of the droplet collection and detection area corresponding to the 3rd row and 3rd column in Embodiment 2 of this application.

[0037] Figure 10 This is a schematic image of the exit point of the last transition section of the discrete magnetic bead functional region in Experiment Group 2 of this application.

[0038] Figure 11 This is a schematic image of the exit point of the last transition section of the discrete magnetic bead functional region in Experiment Group 3 of this application.

[0039] Figure labeling: 11, Inlet; 12, Enrichment bead functional area; 120, Magnetic component; 121, First position; 122, Second position; 123, Filter column array; 13, Discrete bead functional area; 130, Discrete unit; 131, Acceleration section; 132, Transition section; 133, Deceleration section; 134, Bend; 14, Droplet generation port; 15, Droplet collection and detection area; 16, Oil phase transport channel. Detailed Implementation

[0040] The following is in conjunction with the appendix Figures 1 to 11 This application will be described in further detail below.

[0041] The technical solutions in the embodiments of this application will be further described in detail below with reference to the accompanying drawings. The described embodiments are only possible technical implementations of this application, but are not limited thereto. Other embodiments obtained by those skilled in the art in conjunction with the embodiments of this application without creative effort are also within the protection scope of this application.

[0042] Combination Figure 1As shown, this application provides a chip for enriching and dispersing magnetic beads, including an inlet 11, an enrichment magnetic bead functional area 12, a dispersion magnetic bead functional area 13, a droplet generation port 14, an oil phase transport channel 16, and a droplet collection and detection area 15. The inlet 11, enrichment magnetic bead functional area 12, dispersion magnetic bead functional area 13, and droplet generation port 14 are arranged sequentially and interconnected along the flow direction of the fluid reagent. This allows a fluid reagent containing magnetic beads (typically an aqueous phase) to enter through the inlet 11, whereby the magnetic beads are enriched in the enrichment magnetic bead functional area 12 and dispersed in the dispersion magnetic bead functional area 13 before reaching the droplet generation port 14 along with the fluid reagent. The oil phase transport channel 16 is distributed around the inlet 11, enrichment magnetic bead functional area 12, and dispersion magnetic bead functional area 13 (e.g., on both sides), and is used to transport another fluid reagent (typically an oil phase) to the droplet generation port 14 to generate droplets. The droplet collection and detection area 15 is located downstream of the droplet generation port 14 along the flow direction. It is used to collect the generated droplets and perform related operations.

[0043] In one embodiment, the injection port 11 is used to introduce a fluid reagent containing magnetic beads. A magnetic bead enrichment region 12 is connected to the injection port 11 and is used to cooperate with a magnetic element 120 movably disposed along the flow direction of the fluid reagent. The magnetic force of the magnetic element 120 attracts the enriched magnetic beads and drives the enriched magnetic beads to move along the flow direction. A discrete magnetic bead region 13 is connected to the magnetic bead enrichment region 12 and is used to receive and disperse the enriched magnetic beads. The discrete magnetic bead region 13 is provided with a plurality of discrete units 130, the cross-sectional width of which first decreases and then increases along the flow direction.

[0044] Understandably, by setting up the enrichment magnetic bead functional area 12 and the discrete magnetic bead functional area 13, a two-step operation of "enrichment followed by dispersion" of magnetic beads is achieved within the chip. First, the movable magnetic component 120 can form a locally high-concentration magnetic bead suspension in the enrichment magnetic bead functional area 12 without changing the initial sample concentration, thus creating conditions for the subsequent generation of a large number of droplets containing single magnetic beads. Second, the subsequent discrete magnetic bead functional area 13 guides the fluid to impact the magnetic bead agglomerates through changes in the cross-section of the flow channel, solving the problem of magnetic bead agglomeration and adhesion that is inevitable due to magnetic field enrichment, and avoiding the risk of blockage caused by magnetic bead agglomerates directly entering the downstream microchannel. This solves the dilemma in the background technology where increasing the magnetic bead concentration leads to agglomeration and blockage, while not increasing the concentration results in low yield of single-pack droplets. It can effectively increase the absolute number and proportion of single-pack magnetic bead droplets with a limited total droplet volume, achieving a dual improvement in detection efficiency and accuracy.

[0045] In this embodiment, the flow channel height of the chip for enriching and dispersing magnetic beads is about 10 μm, and the linewidth of the droplet generation port 14 is about 10 μm. The required parameters can be further configured according to the required particle size and the size of the magnetic beads.

[0046] Further integration Figure 2 As shown, in one embodiment, the magnetic component 120 is movably disposed between a first position 121 and a second position 122 along the flow direction. Both the first position 121 and the second position 122 correspond to the enrichment magnetic bead functional region 12 and are distributed at intervals along the flow direction. A filter column array 123 is also provided at the junction of the enrichment magnetic bead functional region 12 and the discrete magnetic bead functional region 13. The first position 121 is closer to the injection port 11 than the second position 122, and the second position 122 is closer to the filter column array 123 than the first position 121.

[0047] In this embodiment, the magnetic element 120 can be a magnet, and the magnetic element 120 overlaps with the projection of the flow channel. The first position 121 is set close to the injection port 11. Since the magnetic element 120 at the first position 121 is close to the injection port 11, the magnetic force of the magnetic element 120 is relatively large at this time, so that the magnetic beads are quickly attracted and enriched (e.g., 5 to 15 seconds). The second position 122 is close to the filter column array 123. During the process of the magnetic component 120 moving from the first position 121 to the second position 122, the enriched magnetic beads are magnetically pulled downward along the flow direction to the inlet close to the filter column array 123. The magnetic component 120 pulls the enriched magnetic beads to a position closer to the filter column array 123 relatively completely and smoothly. This ensures that the enriched magnetic beads can smoothly enter the filter column array 123 region after the magnetic constraint is removed, and further enter the discrete magnetic bead functional area 13 in the later stage. The enriched magnetic beads will not be unable to reach the filter column array 123 region smoothly due to the premature removal of the magnetic force at the first position 121 (for example, some of them will be piled up on the wall edge of the narrowing flow channel region between the first position 121 and the second position 122).

[0048] In this embodiment, the filter column array 123 includes a plurality of densely arranged micro-filter columns. On the one hand, the filter column array 123 can filter out larger foreign objects in the fluid reagent, preventing the downstream flow channel from being blocked. On the other hand, the filter column array 123 can also initially disperse the already enriched magnetic beads.

[0049] Understandably, this two-stage enrichment design and the arrangement of the filter column array 123 further optimize the enrichment and dispersion effects. First, the magnetic component 120 is positioned at a first position 121 closer to the injection port 11, shortening the distance between the magnetic component 120 and the magnetic beads flowing out of the injection port 11, enhancing the attraction effect of the magnetic component 120 on the magnetic beads, and enabling the enrichment of magnetic beads to be completed quickly in a shorter time. Then, the magnetic component 120 is moved to a second position 122 closer to the filter column array 123. The enriched magnetic beads follow the magnetic force to a position closer to the filter column array 123, preventing the magnetic beads from being unable to enter the dispersion magnetic bead functional area 13 due to adsorption on the flow channel wall when flowing naturally; this ensures both the high efficiency of the enrichment of magnetic beads and the stability of the magnetic bead flow. Secondly, while filtering out potential large-sized impurities as a safety barrier, the filter column array 123 also plays a preliminary mechanical dispersing and pre-dispersing role on the magnetic bead agglomerates that are about to enter the discrete region, reducing the burden on the subsequent discrete unit 130 and making the synergistic effect of the entire "enrichment-dispersion" process better and more efficient.

[0050] Further integration Figure 3 and Figure 4 As shown, in one embodiment, the discrete unit 130 includes an acceleration section 131, a transition section 132, and a deceleration section 133 arranged sequentially along the flow direction. The transition section 132 connects the acceleration section 131 and the deceleration section 133. The cross-sectional width of the flow channel in the acceleration section 131 gradually decreases along the flow direction, while the cross-sectional width of the flow channel in the deceleration section 133 gradually increases along the flow direction. The two ends of the transition section 132 along the flow direction are respectively connected to the minimum cross-sectional width of the flow channel in the acceleration section 131 and the minimum cross-sectional width of the flow channel in the deceleration section 133.

[0051] Understandably, the discrete unit 130 is specifically defined as an acceleration section 131, a transition section 132, and a deceleration section 133. The fluid carrying the magnetic bead agglomerates gradually increases in velocity in the acceleration section 131, reaching a peak velocity in the narrowest transition section 132, and then abruptly decreases in velocity in the deceleration section 133. This drastic cycle of velocity increases and decreases subjects the magnetic bead agglomerates to strong fluid shear and inertial forces, effectively separating the magnetic beads aggregated by magnetic or van der Waals forces. This significantly improves the discrete efficiency and monodispersity of the magnetic beads, ensuring a high proportion of individually packaged magnetic bead droplets.

[0052] It should be explained that, under the condition of a basically constant flow rate, the fluid velocity increases as the width of the flow cross section decreases, and also decreases as the width of the cross section increases. "Cross section" refers to the cross-section corresponding to a plane substantially perpendicular to the flow direction of the fluid reagent containing magnetic beads in the chip containing enriched and discrete magnetic beads. The width of the cross section corresponds to the width of the flow channel, which varies with the structure. The flow channel of the chip containing enriched and discrete magnetic beads used in this application is a three-dimensional flow channel. "Cross-sectional width of the flow channel" can also be understood as "cross-sectional area of ​​the flow channel." Those skilled in the art should understand that the trend of fluid velocity change in the discrete unit 130 is clear. In this embodiment, for a single discrete unit 130, the cross-sectional width first gradually decreases along the flow direction (corresponding to acceleration section 131, where the velocity gradually increases), then remains approximately constant or fluctuates within a small range (corresponding to transition section 132, where the velocity is fastest in the discrete unit 130), and then gradually increases again (corresponding to deceleration section 133, where the velocity gradually decreases).

[0053] In this embodiment, the flow channel of the acceleration section 131 is an arc shape with a cross-sectional width that gradually decreases along the flow direction, and the flow channel of the deceleration section 133 is an arc shape with a cross-sectional width that gradually increases along the flow direction.

[0054] Understandably, the use of an arc-shaped flow channel design makes the changes in channel width smoother and more continuous, effectively avoiding fluid dead zones or eddies at corners and ensuring a more uniform and stable flow field distribution. This not only reduces the risk of magnetic beads accidentally getting stuck or deposited in the flow channel, but also ensures that each magnetic bead entering the discrete unit 130 undergoes a controllable and consistent acceleration and deceleration process, thereby improving the uniformity and reliability of the discrete process.

[0055] In one embodiment, the ratio of the maximum to the minimum width of the flow channel cross-section of the discrete unit 130 ranges from 10 to 100.

[0056] In this embodiment, the ratio of the maximum to the minimum cross-sectional width of the flow channel of the discrete unit 130 can specifically be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 4 9, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100. Within a single discrete unit 130, the larger the ratio of the maximum to the minimum cross-section, the more drastic the velocity change of the magnetic bead as it passes through the unit, resulting in a better dispersion effect.

[0057] Understandably, limiting the aspect ratio to 10 to 100 ensures that sufficiently drastic velocity changes can be generated within the discrete unit 130. According to fluid dynamics principles, a larger aspect ratio means that the fluid experiences a significant velocity difference between the acceleration section 131 and the deceleration section 133, thus generating extremely strong shear forces. The aspect ratio range of 10 to 100 is an experimentally optimized range that ensures the generated fluid forces are sufficient to overcome the attractive forces between the magnetic beads, achieving efficient discretization, while avoiding problems such as excessively high driving pressure or manufacturing difficulties caused by an excessively large aspect ratio.

[0058] In one embodiment, there are multiple discrete units 130, and the multiple discrete units 130 are connected sequentially along the flow direction.

[0059] In this embodiment, the number of discrete units 130 can be set to eight, which are arranged sequentially along the flow direction and connected end to end. The inlet of the acceleration section 131 of the upstream discrete unit 130 along the flow direction receives the enriched magnetic beads dispersed by the filter column array 123. The outlet of the deceleration section 133 of this discrete unit 130 is connected to the inlet of the acceleration section 131 of the next discrete unit 130. Subsequent discrete units 130 are arranged sequentially. The deceleration section 133 of the downstream discrete unit 130 along the flow direction is connected to the droplet generation port 14, realizing the connection between the entire discrete magnetic bead functional area 13, the enriched magnetic bead functional area 12, and the droplet generation port 14. In adjacent discrete units 130, a corresponding filter column array can also be provided between the deceleration section 133 of the previous discrete unit 130 and the acceleration section 131 of the next discrete unit 130 to improve the filtration effect and ensure smooth flow.

[0060] In other embodiments, the number of discrete units 130 can be adjusted according to actual conditions. As the number of discrete units 130 connected in series increases, the discretization effect will gradually strengthen until it reaches saturation.

[0061] In one embodiment, each discrete unit 130 includes a transition section 132, the cross-sectional width of which is smaller than that of another transition section 132 located upstream of it along the flow direction. That is, along the flow direction, the cross-sectional width of the flow channels corresponding to the multiple transition sections 132 gradually decreases, meaning that the velocity of the magnetic bead gradually increases in different transition sections 132 (which is also the stage where the magnetic bead has the fastest velocity in a single discrete unit 130), thus enabling the stepwise discretization of the enriched magnetic beads.

[0062] In this embodiment, the variation trend of the cross-sectional width of the flow channel corresponding to the multiple transition sections 132 set along the flow direction can be, for example, 90μm, 80μm, 70μm, 60μm, 50μm, 40μm, 30μm, and 20μm, to achieve step-by-step discreteness of the magnetic beads.

[0063] Understandably, a progressively discretized (or gradually dispersed) system is constructed by setting up multiple discrete units 130. The enriched large magnetic bead agglomerates are first initially dispersed into smaller agglomerates in the upstream discrete unit 130, which has a wider flow channel and a relatively lower flow velocity. These smaller agglomerates then enter the downstream unit, which has a narrower flow channel and a higher flow velocity, for further discretization. This progressive processing method can efficiently handle magnetic bead agglomerates of various sizes, avoiding the problem of a single extremely narrow channel being directly blocked by large magnetic bead agglomerates, thus ensuring greater thoroughness and robustness in the discretization of enriched magnetic beads.

[0064] In the deceleration section 133, it can be observed that after the gradual acceleration in the acceleration section 131 and the fastest speed in the transition section 132, the magnetic beads that flow into the deceleration section 133 and gradually decelerate exhibit less magnetic aggregation and more individual discreteness. After multiple cycles, the vast majority of the magnetic beads eventually exhibit an individual discrete state.

[0065] Further integration Figure 3 As shown, in one embodiment, the flow channel of the transition section 132 is configured to be straight along the flow direction.

[0066] Understandably, constructing the transition section 132 as a straight line is a simple and easily microfabrication solution. This design simplifies the chip manufacturing process, reduces production costs, and improves chip yield and flow channel stability while ensuring the fluid reaches maximum velocity to generate effective shear force, thus achieving both cost-effectiveness and reliability. Furthermore, through step-by-step acceleration and discretization, most magnetic beads can be discretized into individual beads, representing a significant improvement over typical chips that rely on enriched and discrete magnetic beads.

[0067] Further integration Figure 4 As shown, in one embodiment, the flow channel of the transition section 132 is configured to be curved along the flow direction and has multiple bends 134. The curved flow channel is designed to increase the collision between the magnetic beads and the wall, which is beneficial for the dispersion of the magnetic beads.

[0068] Understandably, compared to the straight transition section 132, the curved flow channel introduces an additional dispersion mechanism. When the magnetic bead agglomerates flow at high speed through the bend 134, due to inertial effects, the larger magnetic bead agglomerates tend to detach from the streamline and collide with the flow channel wall. The combined effects of fluid shearing and physical collision greatly enhance the force on the magnetic bead agglomerates, especially for tightly bound agglomerates, where the dispersion effect is more significant, thereby further improving the yield of individual magnetic beads.

[0069] In one embodiment, the flow channel of the transition section 132 extends in a wavy manner along the flow direction, and the bending angle of the bend 134 relative to the flow direction is 60° to 120°.

[0070] In this embodiment, the angle at which the bend 134 bends relative to the flow direction can specifically be 60°, 61°, 62°, 63°, 64°, 65°, 66°, 67°, 68°, 69°, 70°, 71°, 72°, 73°, 74°, 75°, 76°, 77°, 78°, 79°, 80°, 81°, 82°, 83°, 84°, 85°, 86°, 87°, 88°, 89°, 90°, or 91°. °, 92°, 93°, 94°, 95°, 96°, 97°, 98°, 99°, 100°, 101°, 102°, 103°, 104°, 105°, 106°, 107°, 108°, 109°, 110°, 111°, 112°, 113°, 114°, 115°, 116°, 117°, 118°, 119°, 120°. In this embodiment, 90° is selected as an example for demonstration.

[0071] Understandably, the wavy flow channel design causes the magnetic beads to experience multiple, alternating wall collisions during their advancement, achieving a continuous and efficient discretization process. Limiting the bending angle to between 60° and 120° represents an optimized balance between discretization effectiveness and smooth flow: too small an angle results in insufficient collision force and poor discretization; too large an angle may lead to a significant increase in fluid resistance or even blockage of the magnetic beads. This preferred angle range ensures that the magnetic beads can withstand sufficiently strong impact forces for effective separation, while maintaining the stable operation of the entire chip for enriching and discretizing magnetic beads.

[0072] It is understood that the chip for enriching and dispersing magnetic beads provided in this application embodiment first enriches the magnetic beads in the enrichment magnetic bead functional area 12 to obtain a high concentration of magnetic beads within a certain range, and then disperses the enriched magnetic beads in the dispersing magnetic bead functional area 13 to obtain more single-pack magnetic bead droplets in the future, thereby achieving efficient detection.

[0073] Further integration Figure 5 As shown, this application also provides an operation method for a chip that enriches and discretes magnetic beads, using the chip that enriches and discretes magnetic beads as described in any of the foregoing embodiments, including the following steps: Step S1: Add the aqueous fluid reagent containing magnetic beads that has completed the immunoreaction to the injection port 11, and turn on the drive to generate droplets at the droplet generation port 14 of the chip enriched and dispersed with magnetic beads.

[0074] Specifically, add a fluid reagent containing magnetic beads (e.g., 10 μL, concentration 50,000 / μL) to the chip injection port 11 to complete the immune reaction, turn on the pneumatic drive, and ensure that the fluid reagent can flow stably in the flow channel until droplets begin to be generated stably.

[0075] Step S2: Move the magnetic component 120 to a first position 121 close to the injection port 11 and stay there for a period of time to enrich the magnetic beads. Move the magnetic component 120 along the flow direction to a second position 122 that is closer to the discrete magnetic bead functional area 13 than the first position 121, so as to drive the enriched magnetic beads to move to the discrete magnetic bead functional area 13.

[0076] Specifically, the magnetic component 120 is placed in the first position 121 for about 5 to 15 seconds, so that the magnetic beads flowing in from the injection port 11 are magnetically attracted and enriched. Then the magnetic component 120 is transferred from the first position 121 to the second position 122 and stays there for a period of time to allow the enriched magnetic beads to follow stably. The final equivalent concentration can reach about 818,400 / μL, which is far beyond the conventional reagent operation concentration.

[0077] Step S3: Release the magnetic field constraint on the magnetic bead, so that the magnetic bead is driven into the discrete magnetic bead functional area 13, and accelerates and then decelerates in the discrete unit 130 to achieve discreteness.

[0078] Specifically, the magnetic component 120 is removed, the magnetic field constraint is released, and the enriched magnetic beads are driven to flow naturally with the fluid reagent into the downstream discrete magnetic bead functional region 13. In the discrete magnetic bead functional region 13, the enriched magnetic beads are gradually dispersed by several discrete units 130 to obtain enriched and discrete magnetic beads.

[0079] Step S4: The aqueous fluid containing the magnetic beads enriched in step S2 and discrete in step S3 is mixed with the oil fluid at the droplet generation port 14 to generate several target droplets. Some of the target droplets contain a magnetic bead. The target droplets enter the droplet collection and detection area 15.

[0080] Specifically, after the magnetic beads pass through the discrete magnetic bead functional area 13, the enriched and discrete magnetic beads reach the droplet generation port 14. The aqueous fluid reagent containing the magnetic beads interacts with the oil fluid reagent at the droplet generation port 14 to obtain the target droplet.

[0081] Step S5: In the droplet collection and detection area 15, droplets within a certain period from the start of the target droplet generation to the stop time node are collected as detection droplets for detection.

[0082] Specifically, the stopping time point typically corresponds to the time when the leading edge of the target droplet (enriched single-packed magnetic bead droplet) reaches the end of the droplet collection and detection area 15. Before the enriched and discrete magnetic beads reach the droplet generation port 14, the droplets collected in the droplet collection and detection area 15 are mostly empty droplets. After the enriched and discrete magnetic beads reach the droplet generation port 14, a large number of target droplets begin to enter the droplet collection and detection area 15, gradually squeezing out the existing empty droplets in the droplet collection and detection area 15. From the time the enriched and discrete magnetic beads reach the droplet generation port 14 until the subsequent time period, the magnetic bead concentration at the droplet generation port 14 gradually decreases, and the concentration of single-packed magnetic bead droplets in the continuously generated target droplets is lower than the concentration of single-packed magnetic bead droplets in the initially generated target droplets. That is, assuming the volume of the droplet collection and detection area 15 remains approximately constant, when the tip of the target droplet reaches the end of the droplet collection and detection area 15, the previously collected waste liquid containing a large number of empty droplets has been fully discharged. Furthermore, if collection continues afterward, the number of single-packed magnetic bead droplets in the target droplet will decrease, making it unsuitable for further detection. Therefore, when the tip of the target droplet reaches the end of the droplet collection and detection area 15, the amount of single-packed magnetic bead droplets within the area is at its maximum, making the efficiency of including this portion in the detection significantly better. At the stop time point, the drive can be shut down to stop the generation of subsequent droplets.

[0083] Understandably, by precisely controlling the position and duration of the magnetic component 120 (step S2) and timely releasing the magnetic field (step S3), a high-concentration and monodisperse magnetic bead flow can be actively and controllably generated in the flowing system. Simultaneously, combined with the selective interception strategy in step S5, the high-value droplet region generated by the magnetic bead flow is precisely captured, while empty droplets in the low-concentration regions before and after are discarded. This allows detection resources to be fully concentrated on the sample with the highest information density, significantly shortening the effective data acquisition time and improving detection throughput and instrument utilization efficiency.

[0084] Further integration Figure 6 As shown, in one embodiment, the time when the magnetic component 120 moves to the first position 121 in step S2 is t1, the time when the magnetic field constraint is released in step S3 is t2, the time when the target droplet is formed in step S4 is t3, and the time when the target droplet is stopped in step S5 is t4. Specifically, during the time period from t1 to t2, the magnetic bead concentration at the droplet generation port 14 remains essentially constant; during the time period from t2 to t3, the magnetic bead concentration at the droplet generation port 14 first remains essentially constant and then increases, reaching its maximum at t3; during the time period from t3 to t4, the magnetic bead concentration at the droplet generation port 14 gradually decreases; and during the time period from t3 onwards, the rate of decrease in the magnetic bead concentration at the droplet generation port 14 gradually decreases.

[0085] Understandably, this embodiment defines the characteristic curve of the magnetic bead concentration change over time at the 14 droplet generation ports. This characteristic curve clearly depicts the concentration change trend over time generated by the entire process of "enrichment-dispersion-transport," verifying that the method can generate a magnetic bead flow with significant peaks and predictable morphology. The operator can precisely set the cutoff window from t3 to t4 based on this predictable concentration change pattern, thereby ensuring that the highest quality test samples are obtained in each experiment, improving the accuracy and consistency of the test results.

[0086] Regarding the chip and its operation method for enriching and dispersing magnetic beads provided in this application embodiment, with the initial magnetic bead concentration remaining constant, magnetic beads are enriched in a local area using a magnetic field, causing a sharp increase in the concentration of magnetic beads in that local area. In actual operation, the intensity, position, and duration of the magnetic field can be adjusted to control the degree of enrichment. During the enrichment process, magnetic beads may aggregate and adhere, a state that is generally unsuitable for direct droplet generation. Therefore, by setting multiple rounds of fluid acceleration and deceleration cycles (or including the effect of curved flow channels to accelerate the collision of magnetic beads with the wall), the enriched magnetic beads are dispersed. Through the above-described enrichment and dispersion process, a local high concentration of magnetic beads can be obtained. Combined with the interception of high-concentration target droplets, a very large total amount of single-pack magnetic bead droplets can be obtained with a limited number of droplets generated, significantly improving detection efficiency.

[0087] Experimental group 1: Chip structure parameters: adopted Figure 7 The chip structure for enriching and discrete magnetic beads shown has a channel height of 10 μm and a generation port linewidth of 10 μm. It employs 8 discrete units, with the widest cross-sectional width of each discrete unit being 1000 μm. The narrowest cross-sectional widths of the discrete units decrease progressively to 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, and 20 μm, respectively, achieving progressive discreteness of the enriched magnetic beads. The droplet collection and detection area 15 has dimensions of 10 mm * 8 mm.

[0088] Chip fabrication and surface treatment: Chips enriched with and discrete magnetic beads are fabricated from chip molds using PDMS casting technology. Subsequently, hydrophobic reagents are used to hydrophobize the inner surface of the chip channels to facilitate the stable generation of droplets.

[0089] Reagents: The verification experiment was conducted using a fluid reagent containing magnetic beads with the reaction complex after the immune reaction was completed. The volume of the fluid reagent containing magnetic beads was 10 μL and the concentration was 50,000 beads / μL.

[0090] Set up a control group: Both control group 1 and experimental group 1 adopted the following... Figure 7 The same type of enriched and discrete magnetic beads chip is shown. The control group 1 is repeated 3 times to obtain comparative example 1, comparative example 2 and comparative example 3 respectively. The experimental group 1 is repeated 3 times to obtain example 1, example 2 and example 3 respectively.

[0091] It should be noted that discrete magnetic beads are needed after the enrichment of magnetic beads. When the enrichment process is not performed, there is no need for discrete magnetic beads. Therefore, both control group 1 and experimental group 1 used the following... Figure 7In the case of the same type of chip for enriching and dispersing magnetic beads, the concentration of magnetic beads used and other conditions are kept consistent. Control group 1 does not perform magnetic bead enrichment operation, while experimental group 1 performs magnetic bead enrichment operation. The time for experimental group 1 to capture the generated droplets is 70s to 110s after the start of droplet generation. The time for the released magnetic beads after enrichment to reach the generation port is 70s. The time for stopping the driving of droplet generation is 110s. Control group also stops driving droplet generation at 110s.

[0092] Detection and statistics: Using relevant equipment, the droplets in the droplet collection and detection area are scanned, and image processing and data analysis are performed to identify and count the number of droplets, the number of droplets in a single pack of magnetic beads, the number of droplets in multiple packs of magnetic beads, the proportion of droplets in a single pack of magnetic beads, and distribution imaging, etc.

[0093] Results analysis: Table 1. Statistical results of control group 1 and experimental group 1 Table 1 shows the statistical results of control group 1 and experimental group 1: the total number of droplets in both control group 1 and experimental group 1 was around 300,000; the number of single-pack magnetic bead droplets in control group 1 was between 6,000 and 9,000, and the percentage of single-pack magnetic bead droplets was between 2% and 3%; while the total number of single-pack magnetic bead droplets in experimental group 1 was between 80,000 and 90,000, which was about 10 times that of control group 1, and the percentage of single-pack magnetic bead droplets in experimental group 1 was between 24% and 30%, which was also about 10 times that of control group 1. That is, under the same magnetic bead concentration conditions and similar total droplet volume, experimental group 1 obtained approximately 10 times more single-pack magnetic bead solution than control group 1.

[0094] Table 2. Distribution of Comparative Example 3 Table 2 shows the distribution of Comparative Example 3: the droplet collection and detection area is divided into 6 rows and 6 columns according to the image scanning order. The first row represents the position near the droplet generation port, and the sixth row represents the position near the outlet of the droplet collection and detection area. Table 2 shows the number of droplets, the number of single-pack magnetic bead droplets, and the percentage of single-pack magnetic bead droplets in each image. The percentage of single-pack magnetic bead droplets shows that, because Comparative Example 3 did not undergo magnetic bead enrichment, the magnetic bead concentration at the generation port is relatively stable, and the percentage of single-pack magnetic bead droplets in the generated droplets is relatively evenly distributed, mostly between 2% and 3%.

[0095] Table 3. Distribution of Example 2 Table 3 shows the distribution of Example 2: The number and proportion of single-pack magnetic bead droplets show that from the position near the droplet generation port to the position near the droplet collection and detection area outlet, the number and proportion of single-pack magnetic bead droplets gradually increase. This is consistent with... Figure 6 The t3 to t4 segments extracted in the data are consistent; as the generation time progresses, the magnetic bead concentration gradually decreases, and the number of single-pack magnetic bead droplets and the proportion of single-pack magnetic bead droplets also gradually decrease.

[0096] Figure 8 and Figure 9 These are images of the third row and third column positions in the droplet collection and detection areas of Comparative Example 3 and Example 2, respectively; where, Figure 8 The number of liquid droplets in the medium was 12,000, the number of liquid droplets in the magnetic bead was 325, the number of liquid droplets in a single package of magnetic beads was 321, the proportion of encapsulated liquid droplets was 2.71%, and the proportion of liquid droplets in a single package of magnetic beads was 2.68%. Figure 9 The droplet count was 11,004, the magnetic bead droplet count was 3,832, the single-pack magnetic bead droplet count was 2,502, the encapsulation percentage was 25.74%, and the single-pack magnetic bead droplet percentage was 22.74%. It can be seen that in this set of images at the same relative position, the total number of droplets in Comparative Example 3 and Example 2 is approximately 11,000 to 12,000. However, Example 2 has 2,502 single-pack magnetic bead droplets and a single-pack magnetic bead droplet percentage of 22.74%, which is significantly higher than the control group's 321 single-pack magnetic bead droplets and 2.68% single-pack magnetic bead droplet percentage.

[0097] Furthermore, the Poisson distribution was used to perform reverse calculations for Examples 2 and 3. In Comparative Example 3, the encapsulation percentage was 2.66%, resulting in an empty package percentage of 97.34%. The expected value of the corresponding Poisson distribution was 0.027, and the total number of 10μm droplets per μL was 1,910,828, equivalent to a magnetic bead concentration of 51,600 beads / μL, close to the initial condition of 50,000 beads / μL. In Example 2, the encapsulation percentage was 34.84%, resulting in an empty package percentage of 65.16%. The expected value of the corresponding Poisson distribution was 0.4283, equivalent to 818,400 beads / μL. That is, Example 2 achieved a magnetic bead injection concentration equivalent to 818,400 beads / μL, a concentration that is difficult to achieve with conventional reagent handling, micro-volume reagent transfer, and droplet generation.

[0098] Experimental group 2 and experimental group 3: To verify that a flow channel design without bends or deflections in the transition section can still discretize most of the enriched magnetic beads into single beads and a small portion into pairs, and that a flow channel design with bends or deflections in the transition section can further enhance the discretization of the enriched magnetic beads; that is, the acceleration and deceleration cycles of the discrete units play a role in the discretization of the enriched magnetic beads, while the bends or deflections in the transition section further enhance the effect of discretization by strengthening the collision of the magnetic beads with the wall. Experimental groups 2 and 3 were designed as control experiments. A high-speed camera was used to image the magnetic beads at the exit of the fastest stage of the discrete magnetic bead functional region (at the transition section of the last discrete unit). The high-speed camera (1884 FPS) captured images at the exit of the fastest stage when the enriched magnetic beads passed through the last discrete unit. The image acquisition time was 1 second.

[0099] Chip structure parameters: Experimental group 2 adopted Figure 3 The discrete magnetic bead functional region structure shown is used in experimental group 3. Figure 4 The discrete magnetic bead functional region structure shown is consistent with the remaining enriched magnetic bead functional regions, generation port, droplet collection and detection areas. The channel height is 10 μm and the generation port linewidth is 10 μm. Figure 3 The design employs 10 discrete elements, with the values ​​at the narrowest points of the cross-sections of these discrete elements decreasing sequentially at 110μm, 100μm, 90μm, 80μm, 70μm, 60μm, 50μm, 40μm, 30μm, and 20μm. Figure 4 Eight discrete elements are used, and the values ​​at the narrowest points of the cross-sections of the multiple discrete elements decrease in succession to 90μm, 80μm, 70μm, 60μm, 50μm, 40μm, 30μm, and 20μm.

[0100] The chip fabrication, surface treatment, and reagents were the same as those used in Experimental Group 1.

[0101] Results analysis: Further integration Figure 10 As shown, Figure 10 These are images of the last transition segment exit of the discrete magnetic bead functional region in Experimental Group 2; from left to right, they are images at 1 / 1884s, 201 / 1884s, 401 / 1884s, 601 / 1884s, 801 / 1884s, and 1001 / 1884s, respectively. The number of magnetic beads, single magnetic beads, two magnetic beads, three magnetic beads, and four magnetic beads are counted.

[0102] Further integration Figure 11 As shown, Figure 11These are images of the last transition segment exit of the discrete magnetic bead functional region in experimental group 3; from left to right, they are images at 1 / 1884s, 201 / 1884s, 401 / 1884s, 601 / 1884s, 801 / 1884s, and 1001 / 1884s, respectively. The number of magnetic beads, single magnetic beads, two magnetic beads, three magnetic beads, and four magnetic beads are counted.

[0103] Table 4. Statistical results of experimental group 2 and experimental group 3 Table 4 shows the statistical results of experimental group 2 and experimental group 3. The average percentage of a single magnetic bead in experimental group 2 was 57%, while the average percentage in experimental group 3 was 73%. It can be seen that experimental group 2 can achieve a percentage of 57% for a single magnetic bead by using discrete units with multiple acceleration and deceleration cycles. Experimental group 3 added a bending point in the transition section of the discrete unit to enhance the collision between the magnetic bead and the wall, which resulted in a percentage of 73% for a single magnetic bead, an increase of 16 percentage points compared to experimental group 2.

[0104] It should be added that, Figure 10 and Figure 11 These are all static images. Some magnetic beads that appear as single discrete beads in the video may be identified as multiple connected beads in the static images because they are close together. In other words, the actual proportion of single discrete magnetic beads is higher than the statistical value in Table 4.

[0105] The test results from experimental groups 2 and 3 show that the acceleration and deceleration cycles in the discrete unit play an important role in breaking up the magnetic beads. Setting a bend in the transition section can enhance the collision between the magnetic beads and the wall, thereby further enhancing the effect of the discrete magnetic beads.

[0106] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A chip for enriching and dispersing magnetic beads, characterized in that, include: The injection port (11) is used to introduce fluid reagents containing magnetic beads; The enrichment magnetic bead functional area (12) is connected to the injection port (11). The enrichment magnetic bead functional area (12) is used to cooperate with a magnetic element (120) that is movably arranged along the flow direction of the fluid reagent. The magnetic element (120) attracts the enrichment magnetic beads and drives the enriched magnetic beads to move along the flow direction. The discrete magnetic bead functional area (13) is connected to the enriched magnetic bead functional area (12) and is used to attract and disperse the enriched magnetic beads. The discrete magnetic bead functional area (13) is provided with a plurality of discrete units (130). The cross-sectional width of the flow channel of the discrete unit (130) has a trend of first decreasing and then increasing along the flow direction.

2. The chip for enriching and dispersing magnetic beads according to claim 1, characterized in that: The discrete unit (130) includes an acceleration section (131), a transition section (132), and a deceleration section (133) arranged sequentially along the flow direction. The transition section (132) connects the acceleration section (131) and the deceleration section (133). The cross-sectional width of the flow channel of the acceleration section (131) gradually decreases along the flow direction, and the cross-sectional width of the flow channel of the deceleration section (133) gradually increases along the flow direction. The two ends of the transition section (132) along the flow direction are respectively connected to the minimum cross-sectional width of the flow channel of the acceleration section (131) and the minimum cross-sectional width of the flow channel of the deceleration section (133).

3. The chip for enriching and dispersing magnetic beads according to claim 2, characterized in that: The flow channel of the transition section (132) is configured to be straight along the flow direction.

4. The chip for enriching and dispersing magnetic beads according to claim 2, characterized in that: The flow channel of the transition section (132) is configured to be curved along the flow direction and has multiple bends (134).

5. The chip for enriching and dispersing magnetic beads according to claim 4, characterized in that: The flow channel of the transition section (132) extends in a wave-like manner along the flow direction, and the bending angle of the bend (134) relative to the flow direction is 60° to 120°.

6. The chip for enriching and dispersing magnetic beads according to claim 2, characterized in that: The number of discrete units (130) is multiple, and the multiple discrete units (130) are connected sequentially along the flow direction; each discrete unit (130) includes a transition section (132), and the cross-sectional width of the flow channel of one transition section (132) is smaller than the cross-sectional width of the flow channel of another transition section (132) located upstream of it along the flow direction.

7. The chip for enriching and dispersing magnetic beads according to claim 2, characterized in that: The ratio of the maximum to the minimum width of the flow channel cross section of the discrete unit (130) ranges from 10 to 100.

8. The chip for enriching and dispersing magnetic beads according to claim 2, characterized in that: The flow channel of the acceleration section (131) is an arc shape with a cross-sectional width that gradually decreases along the flow direction, and the flow channel of the deceleration section (133) is an arc shape with a cross-sectional width that gradually increases along the flow direction.

9. The chip for enriching and dispersing magnetic beads according to claim 1, characterized in that: The magnetic component (120) is movably disposed between a first position (121) and a second position (122) along the flow direction. The first position (121) and the second position (122) are both disposed corresponding to the enrichment magnetic bead functional area (12) and are distributed at intervals along the flow direction. A filter column array (123) is also provided at the junction of the enrichment magnetic bead functional area (12) and the discrete magnetic bead functional area (13). The first position (121) is closer to the injection port (11) than the second position (122), and the second position (122) is closer to the filter column array (123) than the first position (121).

10. A method for operating a chip that enriches and discretes magnetic beads, characterized in that, The application of the chip with enriched and discrete magnetic beads as described in any one of claims 1 to 9 includes the following steps: Step S1: Add the aqueous fluid reagent containing magnetic beads that has completed the immune reaction to the injection port (11), and turn on the drive to generate droplets at the droplet generation port (14) of the chip enriched and discrete magnetic beads; Step S2: Move the magnetic component (120) to a first position (121) close to the injection port (11) and stay there for a period of time to enrich the magnetic beads. Move the magnetic component (120) along the flow direction to a second position (122) that is closer to the discrete magnetic bead functional area (13) than the first position (121) to drive the enriched magnetic beads to move to the discrete magnetic bead functional area (13). Step S3: Release the magnetic field constraint on the magnetic bead, so that the magnetic bead is driven into the discrete magnetic bead functional area (13), and accelerates and then decelerates in the discrete unit (130) to achieve discreteness; Step S4: The aqueous fluid containing the magnetic beads enriched in step S2 and dispersed in step S3 is mixed with the oil fluid at the droplet generation port (14) to generate several target droplets. Some of the target droplets contain a magnetic bead. The target droplets enter the droplet collection and detection area (15). Step S5: In the droplet collection and detection area (15), droplets within a certain period from the start of the generation of the target droplet to the stop time node are selected as detection droplets for detection.

11. The method for operating a chip for enriching and discrete magnetic beads according to claim 10, characterized in that: The time when the magnetic component (120) moves to the first position (121) in step S2 is t1, the time when the magnetic field constraint is released in step S3 is t2, the time when the target droplet is formed in step S4 is t3, and the time when the target droplet is stopped being intercepted in step S5 is t4. During the time period from t1 to t2, the magnetic bead concentration at the droplet generation port (14) remained basically unchanged; during the time period from t2 to t3, the magnetic bead concentration at the droplet generation port (14) first remained basically unchanged and then increased, reaching its maximum at t3; during the time period from t3 to t4, the magnetic bead concentration at the droplet generation port (14) gradually decreased; and during the time period from t3 onwards, the rate of decrease in the magnetic bead concentration at the droplet generation port (14) gradually decreased.

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