Flow channel shape optimization method and microfluidic device

Abstract

The invention relates to a flow channel shape optimization method and a microfluidic device, the method is used for a flow channel with an obstacle on one side, and the method comprises the following steps: S1, for a semi-cylindrical or semi-elliptic cylindrical obstacle, determining the shape parameter of the obstacle; s2, according to the shape parameters of the obstacle, a corrected shell layer area is arranged in the area, adjacent to the obstacle, in the flow channel; and determining a shape parameter of the corrected shell layer region, so that scattering disturbance of the corrected shell layer region to the flow field is counteracted with scattering disturbance caused by an obstacle. According to the method, the additional flow resistance can be remarkably reduced, the circulation efficiency is improved, and the additional pressure drop caused by obstacles can be effectively eliminated by correcting the counteracting effect of the shell layer area on the scattering effect of the obstacles.

Description

Technical Field

[0001] This invention relates to the field of microfluidic technology, and in particular to a method for optimizing the shape of a flow channel and a microfluidic device. Background Technology

[0002] Microfluidic chips are typically manufactured using a layered bonding structure, where microchannel patterns are fabricated on a lower substrate and then bonded to an upper cover plate for encapsulation. To improve structural rigidity, prevent channel collapse, and enable real-time monitoring, support pillars and various functional sensors are often incorporated into the design. However, these embedded structures significantly alter the original geometry of the channels, triggering a series of significant hydrodynamic effects that directly impact the chip's system performance and operational stability. From an engineering perspective, the main impacts and design challenges are as follows:

[0003] Increased system flow resistance and flow control deviation: Obstacles such as supports force fluid to detour, leading to streamline contraction and increased local velocity, resulting in a significant additional pressure drop. This directly increases the load requirements of the drive pump and, when using constant pressure drive, causes the actual flow rate to be significantly lower than the expected value based on the empty flow channel model. For multi-channel parallel designs that rely on precise flow ratios (such as gradient generators), structural asymmetry within each channel will directly disrupt the uniformity of flow distribution, leading to functional failure.

[0004] Eddies and dead zones cause operational reliability issues: Eddies and flow separation generated downstream of the support column create fluid dead zones. Slow fluid turnover within these dead zones easily leads to sample residue and cross-contamination, a fatal flaw for detection applications requiring continuous sample introduction or replacement. Simultaneously, eddies exacerbate sample diffusion, hindering operations such as particle focusing or precise sorting.

[0005] Sudden abrupt changes in local shear force threaten the viability of biological samples: In the edge regions of obstacles, dramatic changes in flow velocity gradients can generate shear force peaks far exceeding the average level. When chips are used to manipulate fragile samples such as cells, excessively high shear forces can lead to cell damage or death. Furthermore, uneven spatial distribution of shear forces subjects cell populations to uncontrollable mechanical stimulation, introducing experimental variables and severely impacting batch-to-batch reproducibility and data reliability.

[0006] In summary, the fluid effects introduced by the embedded structure of microfluidic chips are a key engineering design constraint. These effects can be effectively managed through simulation-driven design processes, optimization of critical structures, and appropriate selection of the drive system, ensuring the chip's performance, reliability, and repeatability in practical applications. Summary of the Invention

[0007] This invention aims to provide a method and apparatus for optimizing the flow channel shape of microfluidic chips by addressing obstacles (such as pillars and sensors) within the flow channels. Its core objective is to actively counteract the disturbances caused by the obstacles to fluid flow by designing a special corrective shell region in their adjacent areas, without removing or altering the obstacles themselves, thereby restoring the flow characteristics of the main flow field to a near-obstacle-free state.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A flow channel shape optimization method for a flow channel with an obstacle on one side includes the following steps:

[0010] S1: For obstacles that are semi-cylindrical or semi-elliptical, determine the shape parameters of the obstacles;

[0011] S2: Based on the shape parameters of the obstacle, a modified shell region is set in the area adjacent to the obstacle in the flow channel; the shape parameters of the modified shell region are determined so that the scattering disturbance of the flow field by the modified shell region cancels out the scattering disturbance caused by the obstacle.

[0012] A further improvement of the present invention is that the cross-section of the flow channel is rectangular; the obstacle protrudes inward from the obstacle wall and is connected to two opposite adjacent wall surfaces.

[0013] A further improvement of the present invention is that the semi-cylindrical obstacle refers to an obstacle whose projection onto two adjacent walls is a semi-circle; the shape parameters of the obstacle include radius r. c The location of the center line; the modified shell region is adjacent to the region occupied by the obstacle, and the merged region is a semi-cylindrical shape, the center line of which coincides with the center line of the obstacle and has a radius of r. s The distance h between the two adjacent wall surfaces in the modified shell region s The following relationship must be satisfied:

[0014]

[0015] Among them, h b The distance between the two adjacent walls, excluding the modified shell region, is equal to the thickness of the flow channel.

[0016] A further improvement of the present invention is that the semi-elliptical cylindrical obstacle refers to the obstacle whose projection onto the two adjacent walls is semi-elliptical; the shape parameters of the obstacle include (ξ1, η), where ξ1 is the radial coordinate determining the size and flatness of the obstacle ellipse in an elliptical coordinate system, and η is the angular coordinate determining the position of the point on the ellipse circumference; the modified shell region is adjacent to the region occupied by the obstacle, and the merged region is a semi-elliptical cylinder, the focal line of which coincides with the focal line of the obstacle and has a size of (ξ2, η), where ξ2 is the radial coordinate determining the size and flatness of the modified shell ellipse in an elliptical coordinate system, and η is the angular coordinate determining the position of the point on the ellipse circumference; the distance h between the two adjacent walls in the modified shell region... s The following relationship must be satisfied:

[0017]

[0018] Among them, h b The distance between the two adjacent walls, excluding the modified shell region, is equal to the thickness of the flow channel.

[0019] A further improvement of the invention is that, in the modified shell region, the distance h between the two adjacent wall surfaces is... s The distance h between the two adjacent walls, excluding the modified shell region, is greater than the distance h between them. b This forms a recessed region on at least one of the adjacent wall surfaces; the bottom surface of the recessed region is a plane.

[0020] A further improvement of the present invention is that the flow channel is formed by bonding a cover plate and a substrate having a flow channel groove; wherein the bottom surface of the flow channel groove serves as an adjacent wall surface, and an obstacle is disposed on the side of the flow channel groove; and a recessed area of ​​the modified shell region is formed on the bottom surface of the flow channel groove.

[0021] A further improvement of the present invention is that the obstacle includes one or more of the following: a support pillar, a biosensor, a chemical sensor, and a physical quantity sensor.

[0022] A further improvement of the present invention is that, in step S1, for obstacles that are not semi-cylindrical or not semi-elliptical, the outline of the obstacle is filled to form a cylindrical or semi-cylindrical obstacle.

[0023] The present invention also provides a microfluidic device, wherein the interior of the flow channel includes a modified shell region formed by the flow channel shape optimization method described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) Significantly reduce additional flow resistance and improve flow efficiency: By correcting the effect of the shell region on the scattering of obstacles, the additional pressure drop caused by obstacles can be effectively eliminated. This makes the total flow resistance of the optimized flow channel basically equivalent to that of the original flow channel without obstacles, thereby reducing the requirement for external driving pressure and improving the flow efficiency of the fluid.

[0026] (2) Effective elimination of eddies and dead zones, improving operational reliability: This solution can significantly suppress eddies and flow separation phenomena generated downstream of obstacles, avoiding the formation of dead zones. This helps prevent sample residue and cross-contamination, which is crucial for applications requiring continuous and precise fluid manipulation (such as concentration gradient generation, cell culture, and precision detection), improving the operational stability and result reliability of the chip.

[0027] (3) By counteracting the flow field distortion caused by obstacles, this method can restore a uniform flow velocity and shear force distribution in the mainstream region. This is especially important for manipulating shear-sensitive samples such as cells, as it can prevent cells from being damaged by excessively high local shear forces, ensuring the accuracy and reproducibility of experimental results.

[0028] (4) Achieving fluid stealth and high design flexibility: The core idea of ​​this method is to make obstacles invisible in fluid dynamics, that is, the background flow field cannot detect the existence of obstacles. This provides great flexibility for microfluidic chip design, allowing engineers to integrate functional components such as pillars or sensors without sacrificing flow field performance. Attached Figure Description

[0029] Figure 1 A three-dimensional view of the flow channel optimized using the method of the invention;

[0030] Figure 2 A schematic diagram of the flow channel optimized using the method of the invention;

[0031] Figure 3 Finite element simulation diagram of flow in the semi-circular modified shell region;

[0032] Figure 4 Finite element simulation diagram of flow in a semi-elliptical modified shell region;

[0033] Figure 5 The pressure drop characteristics of two modified shell region structures under different flow velocities are compared and analyzed. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0035] This invention provides a method for optimizing flow channel shape. Addressing the scattering effect of obstacles on fluid flow within the channel, a special geometrically modified shell region is designed based on the principle of destructive scattering in fluid dynamics. This modified shell region is precisely planned so that its scattering disturbance direction on the fluid flow field is exactly opposite to the disturbance caused by the obstacle, thereby achieving active compensation and cancellation within the flow channel. This technique perfectly counteracts the flow field disturbance and additional flow resistance caused by obstacles, restoring the velocity distribution and pressure loss of the main channel to the state before obstacles were present. The external background flow field behaves as if no obstacles exist internally, and the entire fluid flow is almost unaffected, greatly improving the flow efficiency and operational stability of the flow channel system. The flow channel designed using this method can control the flow field without altering or removing obstacles, making it widely applicable to various flow channel structures and complex operating conditions, and possessing significant engineering application prospects.

[0036] The flow channel shape optimization method of this embodiment is used for flow channels with an obstacle on one side, and includes the following steps:

[0037] S1: For obstacles that are semi-cylindrical or semi-elliptical, determine the shape parameters of the obstacle.

[0038] like Figure 1 As shown, the method in this embodiment targets a rectangular cross-section for the flow channel 10, which is a typical flow channel shape in the field of microfluidics. An obstacle 20 protrudes inward from the obstacle wall 11 and connects to two opposing adjacent walls 12. The flow channel is formed by bonding a cover plate 30 and a substrate 40 with flow channel grooves; the bottom surface of the flow channel groove serves as one adjacent wall 12, and the other adjacent wall is the lower surface of the cover plate 30. The obstacle 20 is positioned on the side of the flow channel groove; the recessed area of ​​the modified shell region 21 is formed on the bottom surface of the flow channel groove. The cross-sectional shape of the obstacle 20 is semi-cylindrical or semi-elliptical cylindrical, with its top and bottom surfaces fused to the two adjacent walls 12 respectively. Its center line or focal line is located on the obstacle wall and perpendicular to the two adjacent walls. One side of the flow channel serves as the obstacle wall 11, and the curved surface of the obstacle faces the other side of the flow channel. For obstacles containing sensors, the sensor window is formed on the circumferential surface of the obstacle.

[0039] Obstacles include one or more combinations of pillars, biosensors, chemical sensors, and physical quantity sensors. When designing wide microfluidic channels, tiny support pillars are needed inside the channel to prevent the top cover from collapsing under pressure. While these pillars ensure structural stability, they are typical obstacles that cause uneven flow rates, create recirculation zones, and increase flow resistance. The method in this embodiment eliminates the effects of these pillars.

[0040] Many microfluidic chips require real-time monitoring of specific substances in fluids, such as using antibody-immobilized biosensors to capture cancer cells or using electrode chemiluminescence sensors to measure pH. These sensors must extend into the fluid to function, thus acting as obstacles themselves. The method in this embodiment restores smooth laminar flow, protecting the sample. In dense arrays containing multiple sensors, the wake generated by upstream sensors can severely interfere with the measurement accuracy of downstream sensors. The method in this embodiment designs an "invisibility cloak" for each sensor, eliminating its influence on the flow field and ensuring that the fluid flowing to the next sensor is uniform and parallel.

[0041] For obstacles that are neither semi-cylindrical nor semi-elliptical, a minimum-volume envelope method is used to fill the obstacle's outline, forming a cylindrical or semi-cylindrical obstacle. The shape parameters of the obstacle are then determined after filling.

[0042] S2: Based on the shape parameters of the obstacle, a modified shell region is set in the area adjacent to the obstacle in the flow channel; the shape parameters of the modified shell region are determined so that the scattering disturbance of the flow field by the modified shell region cancels out the scattering disturbance caused by the obstacle.

[0043] The fluid flow model in the channel is a Poiseuille flow between flat plates, and the flow velocity satisfies the following distribution:

[0044]

[0045] Where μ is the viscosity coefficient of the fluid, z is the direction perpendicular to the plate, and h is the thickness between the plates. Let P represent the Laplace operator parallel to the flat plate, and let P represent pressure. Assuming there is no additional inflow or outflow within a flow channel, according to the law of conservation of flow, the pressure within the flow channel should satisfy the following equation:

[0046]

[0047] The disturbance of the flow field by semi-cylindrical and semi-elliptical cylindrical obstacles in the flow channel is approximately dipole scattering.

[0048] For a semi-cylindrical obstacle, the projection of the obstacle onto the two adjacent walls is a semi-circle; the shape parameters of the obstacle include radius r. c The location of the center line is also specified, with the center line perpendicular to each of the two adjacent walls. The modified shell region is adjacent to the region occupied by the obstacle, and the merged region is also a semi-cylindrical shape. The center line of this semi-cylindrical shape coincides with the center line of the obstacle and has a radius of r. s The distance h between the two adjacent wall surfaces in the modified shell region s The following relationship must be satisfied:

[0049]

[0050] Among them, h b The distance between the two adjacent walls, excluding the modified shell region, is equal to the thickness of the flow channel.

[0051] In the modified shell region, the distance h between the two adjacent walls s The distance h between the two adjacent walls, excluding the modified shell region, is greater than the distance h between them. b This forms a recessed region on at least one of the adjacent wall surfaces; the bottom surface of the recessed region is a plane.

[0052] For a semi-elliptical cylindrical obstacle, the semi-elliptical cylindrical shape refers to the obstacle's projection onto two adjacent walls forming a semi-ellipse. The obstacle's shape parameters include (ξ1, η), where ξ1 is the radial coordinate determining the size and flatness of the obstacle's ellipse, and η is the angular coordinate determining the position of a point on the ellipse's circumference. The modified shell region is adjacent to the area occupied by the obstacle, and the merged region is a semi-elliptical cylindrical shape. The focal line of this semi-elliptical cylindrical shape coincides with the focal line of the obstacle and has a size of (ξ2, η), where ξ2 is the radial coordinate determining the size and flatness of the modified shell ellipse, and η is the angular coordinate determining the position of a point on the ellipse's circumference. The distance h between the two adjacent walls in the modified shell region... s The following relationship must be satisfied:

[0053]

[0054] Among them, h b The distance between the two adjacent walls, excluding the modified shell region, is equal to the thickness of the flow channel.

[0055] Expressions 3 and 4 are determined based on the principle of destructive scattering. The scattering effect of the modified shell region on the flow field should be completely opposite to that of the obstacle. For a flat semi-elliptical obstacle, the modified shell region is also a semi-elliptical structure, confocal with the obstacle, and its size is (ξ2, η). Assume the original flow channel height is h. b The thickness h of the corrected region shell s Adjustments are needed. The specific calculation method is to first write out the general solution for the pressure in each region, and then substitute the general solution into the boundary conditions, including: the pressure at the boundaries of the blockage zone, the correction zone, and the background zone is continuous, and the flow rate is continuous; the pressure gradient in the background zone is constant, i.e., there is no disturbance.

[0056] like Figure 2 As shown, Figure 1This is a schematic diagram of the flow channel optimized using the method of this embodiment. The diagram includes a 3D view at the top and a cross-sectional view at the bottom to visually demonstrate the structure of the modified shell region and its interaction with the fluid. The arrows on the left indicate the flow direction of the fluid, with the overall flow from left to right. The lower right corner shows the 3D coordinate system (x, y, z), where the z-axis is perpendicular to the flow surface. The background area represents a normal fluid flow region without obstacles or interference, through which the fluid can pass freely. The modified shell region utilizes a special structure to allow the fluid to bypass obstacles and restore the original flow pattern. The blockage region is a structure where obstacles exist, preventing the fluid from passing through. In the diagram, (c, ξ1) and (c, ξ2) represent the boundaries of the obstacle and the modified shell region, respectively. csin(ξ1) and ccos(ξ1) are the semi-axis lengths of the obstacle. The enlarged view in the lower right corner is a cross-sectional view showing a schematic diagram of the modified shell region. b h represents the flow channel height of the background region. s To correct the flow channel height in the shell region.

[0057] The following is based on Figure 2 The specific examples shown illustrate the method of this embodiment, such as... Figure 2 As shown, the blockage area is the region where the obstacle is located, and the obstacle is an elliptical cylinder; the correction area is the correction shell area; and the background area is the rest of the flow channel. In this embodiment, the height of the flow channel near the obstacle is adjusted to form a correction shell area, so that the fluid passing through the obstacle returns to its original flow direction after bypassing the obstacle along the correction shell area. The flow field without passing through the obstacle remains completely undisturbed, and the overall flow resistance of the fluid is restored to the same size as in the case without the obstacle.

[0058] In this embodiment, the commercial finite element simulation software COMSOL Multiphysics was used for verification. The simulation results for the semi-elliptical modified shell region are shown below. Figure 3 In this simulation, which is three-dimensional, only one cross-section is selected for analysis. During the simulation, the left boundary is the inlet, set as a flow boundary condition (1 ml / s), the right boundary is the outlet, set as a pressure boundary condition of 0 Pa, and all other wall surfaces are set as no-slip boundary conditions. Observing the simulation results, we can see that: in the pressure diagram, the channel pressure decreases uniformly from the inlet to the outlet, and the white isobars are evenly distributed; in the velocity diagram, the background velocity is uniformly distributed, while the velocity increases in the modified shell region; in the streamline diagram, streamlines not passing through the modified shell region remain straight, while streamlines passing through the modified shell region return to a straight state after locally bypassing obstacles. All three figures reflect that the modified shell region effectively eliminates the disturbance of the flow field by obstacles. The simulation results for the semi-circular modified shell region are shown below. Figure 4 In the results, the conclusions are consistent with those of the semi-elliptical modified shell region, demonstrating the robustness of the invention to obstacles of various shapes.

[0059] Figure 3 This is a finite element simulation of the flow in a semi-elliptical modified shell region. The flow channel is 15cm long, 3cm wide, and 1mm thick. The focal length of the semi-elliptical obstacle is 2cm, ξ1=0.4; the focal length of the modified shell region is 2cm, ξ1=0.7. (a) The figure shows the pressure distribution of the fluid passing through the modified shell region. The left side is the fluid inlet (flow velocity 1ml / s), and the right side is the outlet (pressure 0Pa). The color scale represents the pressure value (in Pa), and the white line is the isobaric line. It can be seen that even with obstacles in the pipe, the pressure is evenly distributed throughout the region under the adjustment of the modified shell region. (b) The figure shows the velocity distribution of the fluid, with the color scale indicating the velocity magnitude (in cm / s). The velocity increases slightly above the obstacle but is evenly distributed in the background area, and the overall flow is stable, indicating that the modified shell region effectively guides the fluid around the obstacle. (c) The figure shows the streamline distribution of the fluid, clearly showing the path of the fluid bypassing the obstacle after being affected by the modified shell region. The streamlines are smooth and continuous, indicating a flow field without significant disturbance. These three sub-figures visually demonstrate the effect of the modified shell region on controlling fluid pressure, velocity, and flow path when concealing obstacles, similar to the manipulation of light waves by an "invisibility cloak," which can be termed a "fluid dynamic carpet cloak." Overall, the results show that by designing the modified shell region, effective camouflage of the flow field can be achieved, making the external flow almost identical to when the obstacle is absent, thus achieving a stealth effect.

[0060] Figure 5This paper presents a comparative analysis of the pressure drop characteristics of two modified shell region structures at different flow velocities, aiming to demonstrate the corrective effect of the modified shell region on pipe flow resistance. The figure includes two structural forms (semi-elliptical and semi-circular), and compares them through pressure changes at different flow rates. The left side shows the streamline diagrams for the two hood structures; the upper part is semi-elliptical, and the lower part is semi-circular. The streamlines show that the fluid can smoothly bypass the obstacle, indicating the effectiveness of the hood structure. (a) and (c) are the comparative curves of pressure drop versus flow rate for the two structures. The figure plots the pressure drops for three cases: no obstacle (clean pipe), with obstacle (blocked pipe), and modified shell region. It can be seen that the pressure drop of the blocked pipe is significantly higher than the other two; while the pressure drop curve of the carpet hood pipe almost coincides with that of the clean pipe and is much lower than that of the blocked pipe. (b) and (d) show the pressure drop difference between the modified shell region and the clean pipe in the two groups with and without obstacles, respectively, more intuitively representing the corrective effect of the modified shell region on the increase in flow resistance. It can be seen that the pressure drop increase in the modified pipe (modified shell region) is negligible compared to the blocked pipe, which is significantly better than the unmodified pipe. Overall results show that, with the help of the modified shell region design, not only can the flow field uniformity be maintained, but the additional pressure drop caused by obstacles can also be significantly reduced, achieving effective correction of fluid flow disturbances.

[0061] Next, we examine the corrective effect of the method in this embodiment on the increase in flow resistance caused by obstacles in the flow channel. The simulation results are shown in... Figure 5 This section presents simulations of two types of obstacles. By adjusting the inlet flow rate (from 1 ml / s to 10 ml / s), the inlet and outlet pressure differences of three flow channels (an unobstructed channel, a channel with obstacles, and a modified channel with a modified shell region) are extracted to compare the flow resistance. A larger pressure difference indicates greater flow resistance. The simulation results... Figure 5 (a) and (c) reveal that over a wide range of inlet flow rates, the pressure differential in the modified flow channel is essentially the same as that in the unobstructed flow channel, indicating that their flow resistance is basically the same. Conversely, the inlet and outlet pressure differential in the obstructed flow channel is greater than that in both the unobstructed and modified flow channels under various conditions, suggesting a greater flow resistance. Simulation Results Figure 5 Figures (b) and (d) show the inlet and outlet pressure differentials of the obstructed flow path and the modified flow path, compared to the offset values ​​of the unobstructed flow path. The results further demonstrate that, under wide flow boundary conditions, the modified and unobstructed flow paths have almost identical inlet and outlet pressure differentials, while the pressure differential of the obstructed flow path increases continuously with increasing inlet flow rate, indicating greater flow resistance. These results fully demonstrate the ability of the modified shell region to correct for the increase in flow resistance caused by obstructions in the flow path.

[0062] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A flow channel shape optimization method for a flow channel with an obstacle on one side, characterized in that... Includes the following steps: S1: For obstacles that are semi-cylindrical or semi-elliptical, determine the shape parameters of the obstacles; S2: Based on the shape parameters of the obstacle, a modified shell region is set in the area adjacent to the obstacle in the flow channel; the shape parameters of the modified shell region are determined so that the scattering disturbance of the flow field by the modified shell region cancels out the scattering disturbance caused by the obstacle.

2. The flow channel shape optimization method according to claim 1, characterized in that, The flow channel has a rectangular cross-section; the obstacle protrudes inward from the obstacle wall and connects to two opposite adjacent walls.

3. The flow channel shape optimization method according to claim 2, characterized in that, The semi-cylindrical obstacle refers to an obstacle whose projection onto two adjacent walls is a semi-circle; the shape parameters of the obstacle include radius r. c The location of the center line; the modified shell region is adjacent to the region occupied by the obstacle, and the merged region is a semi-cylindrical shape, the center line of which coincides with the center line of the obstacle and has a radius of r. s The distance h between the two adjacent wall surfaces in the modified shell region s The following relationship must be satisfied: Among them, h b The distance between the two adjacent walls, excluding the modified shell region, is equal to the thickness of the flow channel.

4. The flow channel shape optimization method according to claim 2, characterized in that, The semi-elliptical cylindrical obstacle refers to an obstacle whose projection onto two adjacent walls is semi-elliptical. The shape parameters of the obstacle include (ξ1, η), where ξ1 is the radial coordinate determining the size and flatness of the obstacle's ellipse in an elliptical coordinate system, and η is the angular coordinate determining the position of a point on the ellipse's circumference. The modified shell region is adjacent to the region occupied by the obstacle, and the merged region is a semi-elliptical cylinder. The focal line of this semi-elliptical cylinder coincides with the focal line of the obstacle and has a size of (ξ2, η), where ξ2 is the radial coordinate determining the size and flatness of the modified shell ellipse in an elliptical coordinate system, and η is the angular coordinate determining the position of a point on the ellipse's circumference. The distance h between the two adjacent walls in the modified shell region... s The following relationship must be satisfied: Among them, h b The distance between the two adjacent walls, excluding the modified shell region, is equal to the thickness of the flow channel.

5. The flow channel shape optimization method according to claim 2, characterized in that, In the modified shell region, the distance h between the two adjacent walls s The distance h between the two adjacent walls, excluding the modified shell region, is greater than the distance h between them. b This forms a recessed region on at least one of the adjacent wall surfaces; the bottom surface of the recessed region is a plane.

6. The flow channel shape optimization method according to claim 5, characterized in that, The flow channel is formed by bonding a cover plate and a substrate with flow channel grooves; wherein the bottom surface of the flow channel groove serves as an adjacent wall surface, and obstacles are provided on the side of the flow channel groove; the recessed area of ​​the modified shell region is formed on the bottom surface of the flow channel groove.

7. The flow channel shape optimization method according to claim 1, characterized in that, The obstacles include one or more of the following: pillars, biosensors, chemical sensors, and physical quantity sensors.

8. The flow channel shape optimization method according to claim 1, characterized in that, In step S1, for obstacles that are not semi-cylindrical or semi-elliptical, the outline of the obstacle is filled to form a cylindrical or semi-cylindrical obstacle.

9. A microfluidic device, characterized in that, This includes the modified shell region formed by employing the flow channel shape optimization method described in any one of claims 1 to 8.

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