Integrated microfluidic detection chip based on dual-channel flow velocity difference eddy current reinforcement

Abstract

The integrated microfluidic detection chip comprises a liquid conveying channel, the upper end and the lower end of the liquid conveying channel are each provided with an inlet, the center position of the side end of the liquid conveying channel is communicated with a mixing channel, the other end of the mixing channel is communicated with a flow velocity difference channel, and the flow velocity difference channel is communicated with a flow velocity sensor. An electrode detection disc is arranged on the side face of the flow velocity difference channel in a communicating mode, and a circular barrier is fixedly arranged in the electrode detection disc. Compared with a traditional detection chip, the integrated microfluidic detection chip based on dual-channel flow velocity difference vortex enhancement has the following remarkable advantages: a breakthrough in mass transfer limit is achieved: through multiple physical coupling of dual-channel flow velocity difference, incident angle optimization and a circular barrier, substance transmission is converted from single molecule diffusion to active vortex driving; the bottleneck that mass transfer of a microfluidic system is limited is solved, and in-situ dynamic refreshing of a detection interface is realized by an automatically generated discrete sample injection mode.

Description

An integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement Technical Field

[0001] This invention relates to the field of microfluidic chip technology, and more specifically, to an integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement. Background Technology

[0002] Traditional clinical diagnostic methods for cardiovascular diseases rely on large-scale biochemical analyzers and professional personnel, which is time-consuming and labor-intensive. In recent years, microfluidic chip technology has provided innovative solutions for point-of-care testing of cardiovascular diseases due to its miniaturization, integration, low sample consumption, and ability to accurately simulate the biological microenvironment. Especially in the field of cholesterol detection, researchers have developed a variety of biosensor platforms: Wang et al. used nanoporous gold to modify screen-printed electrodes to enhance catalytic activity; Xia et al. used the layered structure of MXene nanosheets to achieve ultrasensitive detection; and non-enzyme sensors have also attracted widespread attention due to their high stability (tolerant to a wide pH / temperature range, long lifespan) and low cost. For example, the PEDOT / taurine composite matrix designed by Thivya et al. can effectively suppress impurity interference.

[0003] Despite continuous iterations in sensor materials, key bottlenecks remain in practical applications: Existing microfluidic chips suffer from limited mass transfer: In microscale channels, fluid behavior is dominated by low Reynolds numbers, exhibiting a highly ordered laminar flow state. Mass transport between different fluids relies almost entirely on slow molecular diffusion, resulting in extremely low migration efficiency of analyte molecules to the electrode surface, severely limiting sensor sensitivity and response speed; Signal saturation and "memory effect": The continuous flow injection mode of traditional microfluidics keeps the detection interface continuously exposed to the product. If the response speed is slow, signal saturation and baseline drift are easily caused, making it difficult to achieve high-resolution continuous detection; Interference from uneven mixing: For markers such as cholesterol, insufficient mixing of the sample and buffer solution leads to uneven concentration distribution in the detection area, causing severe electrochemical signal fluctuations. Summary of the Invention

[0004] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide an integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement. By setting up an integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement, it has the following significant advantages compared with traditional detection chips: Breakthrough in mass transfer limit: Through multiple physical couplings of "dual-channel velocity difference + incident angle optimization + circular obstacle", the mass transport is transformed from single-molecule diffusion to active eddy current driving, solving the bottleneck of limited mass transfer in microfluidic systems; Automatically generated discrete sample introduction mode realizes in-situ dynamic refresh of the detection interface, ensuring the stability and repeatability of data during continuous monitoring, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement, comprising an infusion channel, with an inlet at each of the upper and lower ends of the infusion channel, a mixing channel connected to the center of the side end of the infusion channel, and a velocity difference channel connected to the other end of the mixing channel. An electrode detection disk is connected to the side of the velocity difference channel, and a circular obstruction is fixedly disposed inside the electrode detection disk. The mixing channel includes multiple rhomboid channels arranged in series, each rhomboid channel having a rhomboid structure in the middle, and two recessed baffles arranged at the upper and lower ends of the connection between two rhomboid channels in a staggered manner. The velocity difference channel includes opposing high-speed branches and low-speed branches, with a flow guiding cavity connecting the connection between the high-speed branches and the low-speed branches. Multiple flow blocking cavities are arranged in series from top to bottom on the side of the low-speed branch near the flow guiding cavity, with the front end curvature of the flow blocking cavity being parabolic and the rear end curvature tightening into a semi-circular arc.

[0006] In a preferred embodiment, the upper and lower ends of the rhombus channel are staggered, the rhombus structure is located at the center of the lower half of the rhombus channel, and the rhombus structure and the upper half of the rhombus channel are positioned with a smaller distance on the left and a larger distance on the right.

[0007] In a preferred embodiment, the angles of the upper and lower ends of the rhomboid channel and the rhomboid structure are α1 and α2, respectively, where α1 = 60° and α2 = 55°.

[0008] In a preferred embodiment, the distance between the recessed baffle and the diamond-shaped channel on one side is b, the depth of the recessed baffle is h, the length is m, and the size ratio of b, h, and m is 3:1:1.

[0009] In a preferred embodiment, with the horizontal axis of the electrode detection disk as the reference line, the incident angles of the high-speed branch and the low-speed branch relative to the electrode detection disk are 0° and 45°, respectively, and the edges of the flow guiding cavity are curved towards the sides of the high-speed branch and the low-speed branch, respectively.

[0010] In a preferred embodiment, the circular obstacle is biased toward one side of the low-speed branch, and the circular obstacle is located in the central region of the shear layer between the high-speed main flow zone and the low-speed secondary flow zone generated by the high-speed branch and the low-speed branch.

[0011] Technical effects and advantages of the present invention: The present invention, by setting up an integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement, has the following significant advantages compared with traditional detection chips: Breakthrough in mass transfer limit: Through multiple physical couplings of "dual-channel velocity difference + incident angle optimization + circular obstacle", the mass transport is transformed from single molecular diffusion to active eddy current driving, solving the bottleneck of limited mass transfer in microfluidic systems; Elimination of baseline drift and memory effect: Through the cooperation of high-speed and low-speed branches, when the two liquid streams rush into the electrode detection plate, a continuously refreshing eddy current can be formed, thereby discretely filling the interior of the electrode detection plate with sample liquid. This discrete sample introduction mode realizes in-situ dynamic refresh of the detection interface. This ensures the stability and repeatability of data during continuous monitoring; precise detection range: the chip, in conjunction with a non-enzyme sensor, can accurately distinguish between ideal cholesterol levels (<5.2mM) and high-risk levels (>6.2mM, where mM is a concentration unit in chemistry, representing millimoles per liter), meeting the clinical decision point requirements of the AHA / NCEP guidelines; high anti-interference and high reliability: through the synergistic integration of an efficient micromixing structure and a functionalized detection interface, it eliminates systematic bias caused by uneven sample concentration distribution, significantly enhances the system's anti-interference performance and detection reliability in complex biological matrix environments, and also ensures excellent recovery and selectivity in complex biological samples (such as human serum). Attached Figure Description

[0012] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is a schematic diagram of the distribution of various functional areas of the present invention; Figure 3 is a schematic diagram of a partial structure of the mixing channel of the present invention; Figure 4 is a schematic diagram of the flow rate difference channel structure of the present invention; Figure 5 is a schematic diagram of the internal cross-sectional structure of the electrode detection disk of the present invention; Figure 6 is a schematic diagram of the dimensions of various angles and recessed baffles in the mixing channel of the present invention; Figure 7 is a schematic diagram of the angle of the low-speed branch injected into the electrode detection disk of the present invention; Figure 8 is a finite element analysis cloud map of the liquid mixing state in the mixing channel of the present invention; Figure 9 is a schematic diagram of the mixing efficiency of the rhomboid structure of the present invention when α2 = 55°; Figure 10 is a schematic diagram of the mixing efficiency of the recessed baffle of the present invention when each dimension is at its optimal value; Figure Figure 11 is a schematic diagram of the total material flux in the Z direction on the electrode surface when the high-speed branch V1 and the low-speed branch V2 of the present invention are injected into the electrode detection disk at 0° and 45° respectively; Figure 12 is a finite element analysis cloud diagram of the local fluid mixing state of the circular obstacle of the present invention; Figure 13 is a finite element analysis cloud diagram of the fluid mixing state in the central region of the electrode detection disk of the present invention; Figure 14 is a finite element analysis cloud diagram of the liquid velocity difference between the high-speed branch and the low-speed branch in the velocity difference channel of the present invention; Figure 15 is a schematic diagram of the dimensional characteristics of the mixing channels d1, d2, d3, and d4 of the present invention; Figure 16 is a schematic diagram of the mixing efficiency of each dimension of the mixing channels d1, d2, d3, and d4 of the present invention at their optimal values.

[0013] The attached diagram is labeled as follows: 1. Infusion channel; 2. Mixing channel; 3. Flow rate difference channel; 4. Electrode detection plate; 5. Circular obstruction; 21. Rhomboid channel; 22. Rhomboid structure; 23. Recessed baffle; 31. High-speed branch; 32. Low-speed branch; 33. Flow guiding cavity; 34. Flow obstruction cavity. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] As shown in Figures 1 to 16, an integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement includes an infusion channel 1, with an inlet at each of its upper and lower ends. A mixing channel 2 is connected to the center of the side end of the infusion channel 1, and a velocity difference channel 3 is connected to the other end of the mixing channel 2. An electrode detection disk 4 is connected to the side of the velocity difference channel 3, and a circular obstacle 5 is fixedly installed inside the electrode detection disk 4. The mixing channel 2 includes multiple diamond-shaped channels 21 arranged in series. Each of the diamond-shaped channels 21 has a diamond-shaped structure 22 in the middle. At the connection of two diamond-shaped channels 21, two recessed baffles 23 are staggered at the top and bottom. The velocity difference channel 3 includes high-speed branches 31 and low-speed branches 32 that are oppositely distributed. The connection between the high-speed branches 31 and the low-speed branches 32 is connected by a flow guide cavity 33. On the side of the low-speed branch 32 near the flow guide cavity 33, multiple flow obstruction cavities 34 are connected in series from top to bottom. The front end of the flow obstruction cavity 34 has a parabolic curvature, and the rear end has a semi-circular curvature.

[0016] The upper and lower ends of the rhombus-shaped channel 21 are staggered. The rhombus-shaped structure 22 is located at the center of the lower half of the rhombus-shaped channel 21, and the rhombus-shaped structure 22 and the upper half of the rhombus-shaped channel 21 are positioned with a smaller distance on the left and a larger distance on the right. The angles between the upper and lower ends of the rhombus-shaped channel 21 and the rhombus-shaped structure 22 are α1 and α2, respectively, where α1 = 60° and α2 = 55°. The distance between the recessed baffle 23 and one side of the rhombus-shaped channel 21 is b. The depth of the recessed baffle 23 is h and the length is m, and b... The size ratio of h and m is 3:1:1. With the horizontal axis of the electrode detection disk 4 as the reference line, the incident angles of the high-speed branch 31 and the low-speed branch 32 relative to the electrode detection disk 4 are 0° and 45°, respectively. The edge of the flow guiding cavity 33 is curved towards the side of the high-speed branch 31 and the low-speed branch 32. The circular obstacle 5 is biased towards the side of the low-speed branch 32, and the circular obstacle 5 is located in the central region of the shear layer of the high-speed main flow area and the low-speed secondary flow area generated by the high-speed branch 31 and the low-speed branch 32.

[0017] In Figure 11 of the specification, V1 and V2 represent the high-speed branch 31 and the low-speed branch 32, respectively. Z represents the absolute value of the mass flux in the Z direction on the electrode surface inside the electrode detection disk 4. This flux is directly related to the limiting diffusion current density in the electrochemical reaction, and its physical meaning is the total amount of reactants reaching the unit electrode surface per unit time.

[0018] According to Figures 15-16 in the specification, the dimensional characteristics of the mixing channel 2 are as follows: The length of the diversion section d1 (referring to the longitudinal guiding length of the initial diversion region before the fluid enters the rhomboid channel 21), this parameter determines the incident characteristics of the fluid entering the mixing channel 2; the upper offset distance d2 of the rhomboid channel 21 (referring to the longitudinal offset displacement of the upper half of the rhomboid channel 21 relative to the central axis), this offset design allows the fluid to produce an asymmetric stretching effect; the lower offset distance d3 of the rhomboid channel 21 (referring to the longitudinal offset displacement of the lower half of the rhomboid channel 21 relative to the central axis), the coordinated design of d2 and d3 aims to break the laminar flow... Stable equilibrium induces a stronger secondary flow. The width d4 of the embedded micropore at the center (referring to the lateral width of the rhomboid micropore (or the gap formed by embedded obstacles) at the center of the rhomboid channel 21) enhances mixing by creating a local contraction structure and generating a sudden change in flow velocity. Using the controlled variable method, while keeping other geometric parameters constant, only the target parameter is changed, and the corresponding MI and COP are calculated. (MI: represents solution mixing efficiency; COP: represents the coefficient of performance, defined as the ratio of mixing efficiency to channel pressure drop, aiming to quantify the mixing gain obtained per unit energy cost, and is the most effective way to achieve high mixing performance and low energy loss in chips.) The core evaluation criteria for optimal balance are shown in part (a) of Figure 16. When only the split section length parameter d1 is changed, both the mixing efficiency MI and COP show a non-monotonic trend with the change of d1. When d1=0.14, both reach their maximum values ​​simultaneously, indicating that this size can control the additional pressure drop within a reasonable range while enhancing the degree of fluid splitting and the intensity of induced secondary flow. Therefore, d1=0.14 is selected as the benchmark value for subsequent parameter optimization. Based on this, single-factor scans are performed on d2, d3 and d4 respectively, and the results are shown in (b), (c) and (d) of Figure 16. It can be observed that when d2=0. 11. When d3=0.10 and d4=0.04, both the mixing efficiency MI and COP reach their optimal state (MI: represents solution mixing efficiency, COP: represents performance coefficient, defined as the ratio of mixing efficiency to channel pressure drop, which aims to quantify the mixing gain obtained under unit energy cost, and is the core evaluation criterion for achieving the optimal balance between high mixing performance and low energy loss of the chip). This result shows that reasonably matching the splitting segment length, recombination spacing and local contraction scale helps to form a more uniform and stable velocity distribution during fluid splitting and recombination, while enhancing the transverse momentum exchange and interface renewal rate, thereby significantly improving the convective mass transfer efficiency.

[0019] Figures 11-13 in the instruction manual illustrate the design of the electrode detection area and the optimization of related parameters. For the design of the electrode detection disk 4 area, by changing the angle at which the two solutions output from the flow rate difference channel 3 flow into the electrode detection disk 4, the two solutions mix at the center of the cavity of the electrode detection disk 4, generating a diffusion effect in all directions and forming a rotating vortex on the periphery. This continuously guides the solution into the detection area, thereby improving the detection efficiency of the electrodes within the electrode detection disk 4. The optimization strategy combines parametric scanning with comparative experiments using COMSOL 6.0 to evaluate the absolute value of the mass flux along the horizontal axis of the electrode detection disk 4 surface (this flux is directly related to the limiting diffusion current density in the electrochemical reaction; its physical meaning is the total amount of reactants reaching a unit electrode surface per unit time). By comparing the flux values ​​under different flow rate conditions, the difference in mass transfer efficiency can be objectively quantified. A higher flux value indicates a faster rate of reactant transport to the electrode surface, and a stronger current response signal from the sensor.

[0020] The average flow velocities at the two outlets of the high-speed branch 31 and the low-speed branch 32 within the velocity difference channel 3 can be stably set near the expected targets of 0.150 m / s and 0.050 m / s, respectively, with the velocity ratio strictly maintained at 3:1. The design principle of the velocity difference section within the velocity difference channel 3 is based on comparing performance through the velocity ratio deviation rate. The velocity ratio deviation rate is precisely calculated using the following formula: Velocity ratio deviation rate = |(Actual average velocity ratio - Target velocity ratio) / Target velocity ratio| × 100% = |(Vouter 1 / Vouter 2 - 3) / 3| × 100%, where... V_outlet1 and V_outlet2 represent the outlets of high-speed branch 31 and low-speed branch 32, respectively, i.e., V1 and V2 in Figure 11 of the specification. The advantage of this parameter is that it condenses complex flow field information into a single, dimensionless percentage value. The lower the value, the better the manufacturing precision and flow control performance of the front end. By minimizing this deviation rate, the consistency of conditions in subsequent electrode detection experiments can be ensured, thereby guaranteeing the accuracy and repeatability of the final data. As can be seen from Figure 14, the structure has the lowest minimum deviation rate, which is below 10%.

[0021] The core objective of optimizing the electrode detection chamber is to maximize the transfer rate of reactants to the electrode surface within the electrode detection disk 4, thereby improving the current response sensitivity of the sensor. To this end, this study selects the absolute value of the mass flux in the transverse direction of the electrode surface as the core evaluation index. The physical essence of this index is the limiting diffusion current density, which directly quantifies the number of reactants passing through a unit electrode surface per unit time. Therefore, the flux level objectively reflects the mass transfer efficiency under different flow field configurations. The larger the flux value, the stronger the expected electrochemical signal of the electrode.

[0022] To establish the optimal flow field incident conditions, the synergistic effect of the dual inlet angles and velocity ratios of the high-speed branch 31 and the low-speed branch 32 was systematically studied. The injection angle of the high-speed branch 31 was A1, and the injection angle of the low-speed branch 32 was A2. By designing the angles at which the two solutions flowed into the detection cavity, a diffusion effect was generated after the two solutions mixed in the middle of the cavity, creating a rotating vortex effect on the periphery, continuously drawing the solution into the detection area. The optimization strategy was combined with parametric scanning using COMSOL 6.0 and comparative experiments. The combined method involves first fixing the speed ratio, with the speed ratio of high-speed branch 31 and low-speed branch 32 at 3:1, and optimizing the angle combination. Initially, A1 = 0° (horizontal state) is maintained, and the effect achieved by scanning A2 from 20° to 90° is observed. According to Figure 11 in the instruction manual, the results show that when A2 = 45°, the transverse flux on the electrode surface reaches its first peak, which is 7 mol / s. Subsequently, A2 = 45° is fixed, and A1 is scanned from 20° to 90°. It is found that a local optimum of 3 mol / s can be obtained when A1 = 30°, but the flux value is lower than the former. Then, keeping A2=0° (horizontal state), by changing the angle value of A1 from -90° to -30°, it can be seen that when A1=-60°, the absolute value of the mass flux in the Z direction is the largest, at 5.5 mol / s, but still smaller than 7 mol / s. This phenomenon suggests that the incident angle of the high-speed inlet plays a decisive role in the dominant flow field structure and vortex generation. Therefore, the optimal angles are determined to be A1=0° and A2=45°. By utilizing the coupling and adaptation of the above two angles, the horizontal incident energy of the high-speed fluid can form a high-shear vortex that develops along the electrode surface. The mainstream region of shear force provides a strong overall drive for mass transfer, while the low-speed fluid flows in at a 45° angle, not directly impacting the electrodes. Its main function is to disturb the boundary layer of the mainstream and induce stable Dean vortices (i.e., Dean vortices, a phenomenon that arises from the dynamic balance between centrifugal force and viscous force in a curved pipe: centrifugal force causes the high-speed mainstream to deflect outward, and the reverse pressure gradient forces the fluid to form a reverse backflow along the pipe wall, constituting a double-helix structure). This synergistic mode of horizontal high-speed transport by the mainstream and inclined low-speed stirring by the vortex achieves the optimal balance between convection-enhanced mass transfer and boundary layer thinning.

[0023] To further break through the mass transfer limit, a circular obstacle 5 was introduced inside the electrode detection disk 4. The circular obstacle 5 actively generates controllable flow separation and wake vortices to disturb the flow field. Using the controlled variable method, the four key geometric parameters of the circular obstacle 5 (radius r, distance from the centerline d, depth h, and azimuth angle α3) were optimized sequentially. For depth h optimization, r=0.5mm, d=0.2mm, and α3=0° were fixed, and the scanning range was h (0-0.7mm). The optimal depth was h=0.7mm, at which point the obstruction effect of the sphere on the flow cross section was most significant. For radius r optimization, h=0.7mm was fixed, and the scanning range was r=0.4-1.0mm. The optimal radius was determined to be r=0.8mm. This size achieves a balance between generating sufficiently strong disturbance and avoiding excessive flow resistance. For offset distance d optimization, the sphere was placed at different positions from the centerline of the flow channel (d=0.5-4.5mm). The flux is maximized when d=3.5mm, indicating that placing the obstacle near the shear layer in the high-speed main flow region and the low-speed secondary flow region most effectively transports the generated vortices to the downstream electrode region. Optimization of the azimuth angle α3 was further verified, and it was confirmed that the optimal effect was achieved when the circular obstacle 5 faced the incoming flow (α3=0°), ensuring the symmetry and stability of the flow separation. The final optimal parameters for the circular obstacle 5 were determined to be: r=0.8mm, d=3.5mm, h=0.7mm, α3=0°. The core function of the optimized circular obstacle 5 is to introduce chaotic convection. When the fluid flows through the circular obstacle 5, periodically detached vortices are generated behind it. These vortices superimpose with the main shear flow, greatly enhancing the lateral mixing of fluid particles. To achieve a more uniform reactant concentration distribution, and more importantly, to continuously flush the diffusion boundary layer on the electrode surface inside the electrode detection disk 4, maintaining its thickness at an extremely thin level, and as shown in Figure 12, the streamline diagram of the circular obstacle 5 clearly shows that this structure tears the originally smooth laminar flow into a complex flow field filled with irregular but controllable vortices, and increases the average lateral flux of the electrode surface to its maximum. In summary, an efficient flow field input mode was established through the coordinated optimization of angle and flow velocity, and the parameterized design of the circular obstacle 5 was innovatively introduced. This systematically enhanced the mass transfer process on the electrode surface from both the macroscopic flow field configuration and microscopic flow disturbance levels, providing a clear theoretical basis for the design of high-performance microfluidic electrochemical sensors.

[0024] The working principle of this invention is as follows: Step 1: To achieve highly sensitive electrochemical detection of cardiovascular biomarkers (taking cholesterol as an example), the substance introduction scheme is as follows: Sample test phase: A test solution containing cardiovascular biomarkers, such as pretreated human serum samples, cholesterol standard solutions, or biofluids containing myoglobin, is introduced into the upper inlet of infusion channel 1. This phase provides the target molecules for recognition by the electrochemical sensor; Buffer and electrolyte phase: A phosphate buffer solution (PBS) or other supporting electrolyte with a pH of 7.2–7.4 is introduced into the lower inlet of infusion channel 1. This phase provides stable ionic strength, adjusts the pH of the system to protect the activity of non-enzymatic sensitive membranes, and serves as a dilution phase mixed with the sample phase to adjust the detection range.

[0025] Step 2: After the two streams of material enter the mixing channel 2, the chip as a whole induces chaotic convection of the fluid through a carefully designed channel geometry. A local contraction structure is formed through multiple sets of rhomboid channels 21 and rhomboid structures 22, generating abrupt changes in flow velocity to enhance mixing. The fluid is continuously split, folded, and recombined, significantly increasing the fluid contact interface area. At the same time, while ensuring sufficient lateral migration of the fluid, the shear layer and recirculation zone generated by the fluid are always kept in positions conducive to enhanced mixing. A recessed baffle structure 23 is introduced into the mixing channel 2. Compared with secondary flow induced solely by geometric folding, the recessed baffle 23 can introduce stronger local disturbances under laminar flow conditions, causing significant distortion of the fluid velocity profile. This results in shear enhancement zones and recirculation zones forming before and after the recessed baffle 23, respectively, thereby inducing lateral secondary flow and local recirculation structures, enhancing the stretching and folding process of the fluid, significantly promoting fluid mixing at low Reynolds numbers, and rapidly improving mixing efficiency over a short distance.

[0026] Step 3: By precisely calibrating the geometric parameters, the length of the high-speed branch 31 is set to L1 = 12mm, and the length of the low-speed branch 32 is set to L2 = 3.8mm. After mixing and passing through the mixing channel 2, the liquid enters the velocity difference channel 3 and then passes through the guide cavity 33. Guided by the guide cavity 33, it is equally divided into the high-speed branch 31 and the low-speed branch 32. A portion of the fluid exits from the high-speed branch 31 with its initial velocity after mixing, while the other portion of the fluid, after entering the low-speed branch 32, passes through the interior of multiple flow-blocking cavities 34. Utilizing the parabolic curvature of the front end of the flow-blocking cavity 34 and the abrupt contraction of the rear end into a semi-circular arc, the fluid passes through the interior of the flow-blocking cavity 34... After the fluid direction changes, a local backflow phenomenon is formed at the rear end of the flow-blocking cavity 34, thereby creating a local counter-current effect, which slows down the initial velocity of the fluid. The decelerated fluid is then output from the low-speed branch 32, and the velocity difference between the high-speed branch 31 and the low-speed branch 32 is controlled at 3:1 (0.15 m / s and 0.05 m / s). Subsequently, the high-speed and low-speed fluids converge into the interior of the electrode detection disk 4 at angles of 0° and 45°, respectively. The high-speed, horizontally incident fluid forms a high-shear mainstream zone close to the electrode surface inside the electrode detection disk 4. Furthermore, an unstable interface of shear compression is generated at the confluence of the high-speed and low-speed fluids at the electrode detection disk 4, causing continuous... The fluid flow breaks down into a series of discrete "sample plugs." This fluid confluence method enables periodic dynamic refreshing of the detection interface, completely avoiding signal baseline drift and electrode saturation caused by continuous sample injection inside the electrode detection disk 4. Simultaneously, as the mixed fluid flows through the circular obstacle 5, periodic vortices are generated behind it. These vortices, superimposed on the main shear flow, not only greatly enhance the lateral mixing of fluid micro-particles, resulting in a more uniform reactant concentration distribution, but more importantly, continuously scour the diffusion boundary layer on the electrode surface, maintaining its thickness at an extremely thin level. Furthermore, the circular obstacle 5 tears the originally smooth laminar flow into a complex flow field filled with irregular but controllable vortices. This elevates the average lateral flux on the electrode surface to a new level, with the physical significance of a significant increase in the limiting diffusion current density. When detecting cholesterol, the change in charge transfer resistance Rct is significantly amplified, and the detection limit reaches the femtogram level, far superior to conventional static microfluidic chips. In summary, an efficient flow field input mode was established through the coordinated optimization of angle and flow velocity, and a parametrically designed circular obstacle 5 was introduced. This systematically enhances the mass transfer process on the electrode surface from both the macroscopic flow field configuration and microscopic flow disturbance levels, providing a clear and realistic basis for the design of high-performance microfluidic electrochemical sensors. Ultimately, this completes the entire detection process of the sample.

[0027] Finally, several points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly, and can refer to mechanical or electrical connections, or internal connections between two components, or direct connections. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may change. Second, the accompanying drawings of the embodiments disclosed in this invention only involve structures relevant to the embodiments disclosed in this invention; other structures can refer to common designs. Where there is no conflict, the same embodiment and different embodiments of this invention can be combined with each other. Finally, the above descriptions are merely preferred embodiments of this invention and are not intended to limit this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement, characterized in that: The device includes an infusion channel with an inlet at each of its upper and lower ends. A mixing channel is connected to the center of the side end of the infusion channel, and a flow rate difference channel is connected to the other end of the mixing channel. An electrode detection plate is connected to the side of the flow rate difference channel, and a circular obstruction is fixedly installed inside the electrode detection plate. The mixing channel includes multiple diamond-shaped channels arranged in series. Each diamond-shaped channel has a diamond structure in its center. At the connection point of two diamond-shaped channels, two recessed baffles are arranged at the upper and lower ends in a staggered manner. The flow rate difference channel includes high-speed branches and low-speed branches distributed in opposite directions. A flow guide cavity is connected at the connection point of the high-speed branches and the low-speed branches. Multiple flow obstruction cavities are arranged in series from top to bottom on the side of the low-speed branch near the flow guide cavity. The front end of the flow obstruction cavity has a parabolic curvature, and the rear end has a semi-circular curvature.

2. The integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement according to claim 1, characterized in that: The upper and lower ends of the rhombus-shaped channel are staggered. The rhombus structure is located in the center of the lower half of the rhombus-shaped channel, and the rhombus structure and the upper half of the rhombus-shaped channel are positioned with a smaller distance on the left and a larger distance on the right.

3. The integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement according to claim 1, characterized in that: The angles at the top and bottom ends of the rhomboid channel and rhomboid structure are α1 and α2, respectively, where α1 = 60° and α2 = 55°.

4. The integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement according to claim 1, characterized in that: The distance between the recessed baffle and the diamond-shaped channel on one side is b, the depth of the recessed baffle is h, the length is m, and the size ratio of b, h, and m is 3:1:

1.

5. The integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement according to claim 1, characterized in that: With the horizontal axis of the electrode detection disk as the baseline, the incident angles of the high-speed branch and the low-speed branch relative to the electrode detection disk are 0° and 45°, respectively, and the edges of the flow guiding cavity are curved towards the sides of the high-speed branch and the low-speed branch, respectively.

6. The integrated microfluidic detection chip based on dual-channel velocity difference eddy current enhancement according to claim 1, characterized in that: The circular obstacle is biased towards one side of the low-speed branch road, and the circular obstacle is located in the central region of the shear layer between the high-speed main flow zone and the low-speed secondary flow zone generated by the high-speed branch road and the low-speed branch road.

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