A filter for screening micro-scale particles

Abstract

The application discloses a filter for screening micro-scale particles. A sub-channel is located on the inner side of a main channel, and a filter blade group is arranged between the sub-channel and the main channel. The filter blade group is mainly formed by a plurality of bent filter blades which are uniformly and spacedly arranged along the circumference of the main channel. Each adjacent two bent filter blades form a filter blade inter-flow channel. The main channel and the sub-channel are communicated through the filter blade inter-flow channel. The inlet end and the outlet end of the main channel are communicated with an inlet flow channel and a micro-particle outlet flow channel respectively. The outlet end of the sub-channel is communicated with a filtrate outlet flow channel. After a solid-liquid mixed fluid is filtered through a filter flow channel, the solid particles in the fluid enter the micro-particle outlet flow channel through the main channel, and the filtrate enters the filtrate outlet flow channel through the sub-channel. The application adds a bionic filter blade structure to the filter design by imitating the special feeding filter organ of a manta ray, so that the filter has a better self-cleaning effect and provides a higher filtering efficiency.

Description

Technical Field

[0001] This invention belongs to the field of filter technology in solid-liquid two-phase flow, and specifically relates to a filter for screening microscale particles. Background Technology

[0002] The filter blade structure is a microstructure based on the filter-feeding organs of the manta ray, an improved filter design that mimics the manta ray's feeding and filtration methods. It can be applied in many solid-liquid separation fields, such as wastewater treatment and cell sorting in medical technology. Traditional screening filters often face clogging when high-throughput, long-term operation or high filtration precision and efficiency are required, necessitating frequent screen replacements. This requires stopping the filter's operation and regular maintenance, increasing operating costs. Biomimetic filters, however, effectively prevent contaminant accumulation and clogging on the filter surface without external forces. Simultaneously, the filter's curved channel design improves filtration efficiency, enabling self-cleaning when filtering fine particles, extending the filter's operating time, and reducing economic losses and additional personnel due to downtime for component replacements. This has significant economic and application value. Currently, there is a lack of biomimetic filter structures to improve filtration time and efficiency. Summary of the Invention

[0003] In order to solve the problems existing in the background technology and achieve the above-mentioned self-cleaning function, and to implement a low-cost and high-efficiency treatment solution for the clogging and contamination phenomenon that is difficult to avoid on the filter surface during filter design and use, the purpose of this invention is to provide a filter for screening microscale particles.

[0004] The technical solution adopted in this invention is as follows:

[0005] The filter includes a filter channel, an inlet channel, a microparticle outlet channel, and a filtrate outlet channel. The filter channel has a U-shaped structure, with its inlet end connected to the inlet channel. The inlet channel is connected to an external pressure source, which is used to inject a solid-liquid mixture into the inlet channel. The microparticle outlet channel and the filtrate outlet channel are both connected to the outlet end of the filter channel. After the solid-liquid mixture is filtered through the filter channel, the solid particles and liquid in the solid-liquid mixture enter the microparticle outlet channel and the filtrate outlet channel, respectively, thereby completing the separation and filtration of the solid-liquid mixture.

[0006] The filter channel mainly consists of filter blade inter-channels, a U-shaped main channel, and a U-shaped secondary channel. The secondary channel is located inside the main channel and is parallel to and spaced apart from the main channel. Filter blade groups are arranged between the secondary channel and the main channel. Each filter blade group is formed by several bent filter blades evenly spaced along the circumference of the main channel. Every two adjacent bent filter blades form a filter blade inter-channel. Each filter blade inter-channel is arranged at intervals along the circumference of the main channel to form a filter blade inter-channel array. The filter blade inter-channel array and the filter blade group are located in the same circumferential direction, and the filter blade inter-channels and bent filter blades are arranged alternately along the circumference. The main channel and the secondary channel are connected through the filter blade inter-channels.

[0007] The inlet and outlet ends of the main channel are connected to the inlet flow channel and the microparticle outlet flow channel, respectively. The outlet end of the secondary channel is connected to the filtrate outlet flow channel. After the solid-liquid mixture is filtered through the filter channel, the solid particles in the fluid enter the microparticle outlet flow channel through the main channel, and the filtrate enters the filtrate outlet flow channel through the secondary channel.

[0008] The inlet flow channel includes an inlet circular hole, a steady flow channel, and an inlet direct flow channel. The inlet circular hole is connected to one end of the inlet direct flow channel through the steady flow channel, and the other end of the inlet direct flow channel is connected to the inlet end of the main channel. The inlet circular hole is externally connected to a pressure source for injecting solid-liquid mixed fluid. The steady flow channel and the inlet direct flow channel are used to stabilize the fluid injected into the inlet circular hole so that the fluid forms a stable pipe flow state before entering the main channel.

[0009] The microparticle outlet channel includes a microparticle outlet direct channel and a microparticle outlet circular hole. The outlet end of the main channel is connected to the microparticle outlet circular hole through the microparticle outlet direct channel. The microparticle outlet circular hole is used to collect the discharged solid particles. The filtrate outlet channel includes a filtrate outlet section channel and a filtrate outlet circular hole. The outlet end of the secondary channel is connected to the filtrate outlet circular hole through the filtrate outlet section channel. The filtrate outlet circular hole is externally connected to a filtrate collector.

[0010] Each of the bent filter blades is mainly formed by bending a round-headed elongated structure at one-third of its length. The bending angle of the bent filter blade at the bend is k1 = 150° to 160°. The outer bending surface of the bent filter blade faces the inlet end of the filter, and the inner bending surface faces the outlet end of the filter.

[0011] The side of the bent filter blade closer to the main channel is the leading edge of the bent filter blade, and the side closer to the secondary channel is the trailing edge of the bent filter blade. When the fluid passes through the main channel and the bent filter blade, a fluid vortex is generated near the leading edge, causing the liquid in the fluid to flow along the leading edge of the bent filter blade to the trailing edge, and then enter the filtrate outlet channel through the secondary channel.

[0012] The main channel and the secondary channel share a common center. The radius of the main channel is larger than that of the secondary channel. The radius R2 of the main channel is 5100-5300 μm, and the radius R1 of the secondary channel is 4400-4600 μm.

[0013] The inlet DC channel, the microparticle outlet DC channel, and the filtrate outlet channel all adopt straight channels with a consistent width, and the width of the straight channels is W1 = 150~250μm.

[0014] The size, shape and tilt angle of each bent filter blade in the filter blade group are consistent, the spacing between each two adjacent bent filter blades is consistent, and the minimum spacing between each two adjacent bent filter blades is not less than twice the particle size of the solid particles in the solid-liquid mixture.

[0015] The pressure source is a peristaltic pump.

[0016] The angle between the leading edge of the bent filter blade and the tangent of the central axis of the main channel is 10° to 20°.

[0017] A filter design method for screening microscale particles includes: a flow stabilizing structure and a straight pipe connected to the inlet section to stabilize the fluid injected at the inlet and form a stable pipe flow state, which flows into the main channel. This allows the fluid to achieve normal flow when it flows through the leading edge of the filter blade closest to the inlet section, thus completing the filtration process and avoiding flow field turbulence caused by unstable fluid flow state, which would lead to a decrease in filtration efficiency.

[0018] The inlet wall structure is designed using the same structure as the filter blades, avoiding the problem of a large number of solid microparticles passing through the inlet area and reducing filtration efficiency caused by directly using a vertical wall structure. When the main channel is a U-shaped channel, the fluid flow after entering the main channel is such that the fluid near the filter blades enters the secondary channel through the inter-blade filtration channel for filtration. A small number of microparticles will enter the secondary channel with the fluid through the inter-blade filtration channel, but the microparticles will return to the main channel along the bent trailing edge of the filter blades at the outlet, increasing the filtration efficiency of microparticles.

[0019] The biomimetic filter blade structure mimics the unique feeding filter organs of a manta ray. Flow separation occurs behind the leading edge of each filter blade, generating large eddies within each pore. This means that tiny particles are repelled by the filter rather than passed through. Contact forces cause the particles to "bounce" out of the filter pores and back into the faster-moving free flow. Therefore, particles are collected through the filter's main channel, rather than through the secondary channels (which would cause clogging). This biomimetic filter relies solely on the fluid's own flow characteristics, requiring no external force, to avoid clogging and achieve a self-cleaning filtration effect.

[0020] The biomimetic filter's overall channel structure is designed in a U-shape rather than a straight channel to introduce a Dean secondary flow within the channel. This secondary flow, a relatively small flow perpendicular to the primary flow, disrupts the symmetry of inertial lift by applying additional viscous drag to the particles. This reduces the number of equilibrium positions for particles within the channel and helps them reach their corrected equilibrium positions more quickly. As solid particles move through the channel, the additional Dean force causes their equilibrium positions to be closer to the filter's outer wall. This means particles are less likely to enter the secondary channel through the gaps between the filter blades in the main channel, while particles entering the secondary channel at the inlet section are more likely to return to the main channel through the gaps between the filter blades at the outlet section. Based on these principles, the biomimetic filter can achieve long-term, high-efficiency, and self-cleaning operation.

[0021] This invention completes the microstructure design of a self-cleaning filter to achieve self-cleaning functionality. The filter structure with self-cleaning effect includes an inlet circular orifice, a microparticle outlet circular orifice, a filtrate outlet circular orifice, an inlet flow channel, a microparticle outlet flow channel, a filtrate outlet flow channel, a filter blade assembly that performs the main filtration function, a microparticle collection channel (main channel), and a filtrate collection channel (secondary channel). The blade assembly filters the solution flowing through the main channel. Due to the influence of the blade structure on the flow, vortices are generated at the leading edge of the bent blades, preventing clogging due to long-term use and avoiding the accumulation of solutes and contaminants on the filter structure. Furthermore, the curved structural design reduces the number of particles entering the secondary channel at the inlet section while increasing the number of particles returning to the main channel at the outlet section, thus improving the overall filtration efficiency. This allows the filter made using this structure to operate continuously and efficiently for extended periods. The embodiments of this invention provide verification of the filtration efficiency of the structure under different Reynolds numbers and mixed fluid inlet flow rates.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. This invention utilizes the unique feeding filter organ of a manta ray and adds a biomimetic filter blade structure to the filter design, resulting in a better self-cleaning effect and higher filtration efficiency.

[0024] 2. The bionic filter of the present invention can achieve long-term, high-efficiency, and self-cleaning operation.

[0025] 3. This invention provides a method for manufacturing a self-cleaning filter, which uses soft photolithography to complete the template processing, enabling rapid and low-cost preparation. Attached Figure Description

[0026] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0027] Figure 1 This is a schematic diagram of the filter's microstructure;

[0028] Figure 2 It refers to the parameter configuration for the blade structure and blade arrangement;

[0029] Figure 3 This is a graph showing the changes in the filtration efficiency (%) and inlet flow rate (mL / min) of the filter when filtering 10μm fluorescent particles from a mixed solution of 10μm fluorescent particles.

[0030] Figure 4 This is a graph showing the changes in the filtration efficiency (%) and inlet flow rate (mL / min) of the filter when filtering 15μm fluorescent particles from a mixed solution of 15μm fluorescent particles.

[0031] Figure 5 This is a graph showing the changes in the filtration efficiency (%) and inlet flow rate (mL / min) of the filter when filtering 20μm fluorescent particles from a mixed solution of 20μm fluorescent particles.

[0032] In the diagram, 1 is the main channel; 2 is the filter blade assembly; 3 is the steady flow channel; 4 is the inlet direct flow channel; 5 is the inlet circular hole; 6 is the microparticle outlet direct flow channel; 7 is the microparticle outlet circular hole; 8 is the flow channel between filter blades; 9 is the secondary channel; 10 is the filtrate outlet section flow channel; 11 is the filtrate outlet circular hole; 21 is the inlet of the flow channel between filter blades; 22 is the leading edge; 23 is the trailing edge; and 24 is the outlet of the flow channel between filter blades. Detailed Implementation

[0033] The present invention will be described in detail below with reference to specific implementation examples. These examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way.

[0034] like Figure 1 As shown, the filter includes a filter channel, an inlet channel, a microparticle outlet channel, and a filtrate outlet channel. The filter channel has a U-shaped structure. The inlet end of the filter channel is connected to the inlet channel, which is connected to an external pressure source. The pressure source is used to inject the solid-liquid mixture into the inlet channel. The microparticle outlet channel and the filtrate outlet channel are both connected to the outlet end of the filter channel. After the solid-liquid mixture is filtered by the filter channel, the solid particles and liquid in the solid-liquid mixture enter the microparticle outlet channel and the filtrate outlet channel, respectively, thereby completing the separation and filtration of the solid-liquid mixture.

[0035] The filter channel mainly consists of filter blade inter-channel 8, a U-shaped main channel 1, and a U-shaped secondary channel 9. The secondary channel 9 is located inside the main channel 1, and the secondary channel 9 and the main channel 1 are arranged in parallel and spaced apart. A filter blade group 2 is arranged between the secondary channel 9 and the main channel 1. The filter blade group 2 is mainly formed by several bent filter blades evenly spaced along the circumference of the main channel 1. Each two adjacent bent filter blades form a filter blade inter-channel 8. Each filter blade inter-channel 8 is arranged at intervals along the circumference of the main channel 1 to form a filter blade inter-channel array. The filter blade inter-channel array and the filter blade group 2 are located in the same circumferential direction, and the filter blade inter-channel 8 and the bent filter blades are arranged alternately along the circumference. At least one bent filter blade is arranged between each two adjacent filter blade inter-channel 8. The main channel 1 and the secondary channel 9 are connected through the filter blade inter-channel 8.

[0036] The inlet and outlet ends of the main channel 1 are connected to the inlet flow channel and the microparticle outlet flow channel, respectively. The outlet end of the secondary channel 9 is connected to the filtrate outlet flow channel. After the solid-liquid mixture is filtered through the filter channel, the solid particles in the fluid enter the microparticle outlet flow channel through the main channel 1, and the filtrate enters the filtrate outlet flow channel through the secondary channel 9.

[0037] The inlet flow channel includes an inlet circular hole 5, a steady flow channel 3, and an inlet direct flow channel 4. The inlet circular hole 5 is connected to one end of the inlet direct flow channel 4 through the steady flow channel 3, and the other end of the inlet direct flow channel 4 is connected to the inlet end of the main channel 1. The inlet circular hole 5 is externally connected to a pressure source for injecting solid-liquid mixed fluid. The steady flow channel 3 and the inlet direct flow channel 4 are used to stabilize the fluid injected into the inlet circular hole 5 so that the fluid forms a stable pipe flow state before entering the main channel 1.

[0038] The microparticle outlet channel includes a microparticle outlet direct current channel 6 and a microparticle outlet circular hole 7. The outlet end of the main channel 1 is connected to the microparticle outlet circular hole 7 through the microparticle outlet direct current channel 6. The microparticle outlet circular hole 7 is used to collect the discharged solid particles. The filtrate outlet channel includes a filtrate outlet section channel 10 and a filtrate outlet circular hole 11. The outlet end of the secondary channel 9 is connected to the filtrate outlet circular hole 11 through the filtrate outlet section channel 10. The filtrate outlet circular hole 11 is externally connected to a filtrate collector.

[0039] Each bent filter blade is mainly formed by bending a round-headed, elongated structure at one-third of its length. The bending angle of the bent filter blade at the bend is k1 = 150° to 160°. The outer bending surface of the bent filter blade faces the inlet end of the filter, and the inner bending surface faces the outlet end of the filter. That is, the bent filter blade bulges towards the inlet end of the filter. Figure 2As shown, in the specific implementation, the lengths of each side of the bent filter blade are as follows: L1 = 172 μm, L2 = 323 μm, L3 = 297 μm, L4 = 148 μm. The circle between the blade sides with lengths L1 and L4 is the leading edge of the blade, and the radii of the leading edge and the trailing edge are R4 = 40 μm and R5 = 40 μm, respectively.

[0040] The side of the bent filter blade closer to the main channel 1 is the leading edge 22, and the side closer to the secondary channel 9 is the trailing edge 23. When the fluid passes through the main channel 1 and the bent filter blade, a fluid vortex is generated near the leading edge 22, causing the liquid in the fluid to flow along the leading edge 23 to the trailing edge 23 of the bent filter blade, and then enter the filtrate outlet channel through the secondary channel 9.

[0041] In specific implementation, the side of the filter blade interflow channel 8 closest to the main channel 1 is the filter blade interflow channel inlet 21, and the side closest to the secondary channel 9 is the filter blade interflow channel outlet 24. The liquid in the mixed fluid flows from the filter blade interflow channel inlet 21 to the filter blade interflow channel outlet 24.

[0042] The main channel 1 and the secondary channel 9 share a common center. The radius of the main channel 1 is larger than that of the secondary channel 9. The radius R2 of the main channel 1 is 5100-5300μm, and the radius R1 of the secondary channel 9 is 4400-4600μm. The outline of the curved pipe wall can be obtained by cutting the arc with the same straight line.

[0043] The inlet DC channel 4, the microparticle outlet DC channel 6, and the filtrate outlet section channel 10 all adopt straight channels with a consistent width, and the width of the straight channels is W1 = 150~250μm.

[0044] The size, shape and tilt angle of each bent filter blade in filter blade group 2 are consistent, that is, the center of gravity of all bent filter blades is in the same circumferential direction, the center of gravity of each bent filter blade is equidistant from the center of the main channel 1, the spacing between each two adjacent bent filter blades is consistent, and the minimum spacing between each two adjacent bent filter blades is not less than twice the particle size of the solid particles in the solid-liquid mixture.

[0045] The two ends of the bent filter blades are at the same distance from the main channel 1 and the secondary channel 9, respectively.

[0046] The pressure source is a peristaltic pump.

[0047] The angle k2 between the leading edge 22 of the bent filter blade and the tangent of the central axis of the main channel 1 is 10° to 20°, and the angle k2 corresponding to each bent filter blade is the same; the angle between the leading edge 22 and the trailing edge 23 of the bent filter blade is taken as the angle k1, and the angle k1 corresponding to each bent filter blade is also the same.

[0048] The structure connecting filter blade assembly 2 to the inlet channel is a blade section structure, rather than a simple straight wall surface. This arrangement allows the connection between the flow channel array between the blades and the inlet / outlet flow channels to also be inclined and bent. In the bent filter blades, the intersection of the sides of lengths L1 and L2 is used as the bending point of the bent filter blade. Each bent filter blade is arranged at equal angles with an arc of radius R3 = 5000 μm, ensuring that the minimum distance W2 between adjacent blade channels remains unchanged, where W2 = 43 μm. The side of the filter blade of length L1 is positioned to contact the main channel 1. The smaller of the two included angles formed by the tangents of the filter blade and the center line of symmetry of the main channel 1 is k2 = 13°, and the opening direction of the included angle is towards the inlet section.

[0049] The filter sample is horizontally bonded to a glass slide. The filter channel is fabricated using polydimethylsiloxane (PDMS) molding. A filter blade assembly 2, consisting of 53 identical bent filter blades arranged in a specific pattern, surrounds the main channel 1 of the filter structure. This assembly filters the mixed fluid flowing through the steady-flow channel 3. The main channel inlet is connected to the pressure source inlet orifice 5, which drives the injection of the mixed fluid, via the inlet section channel 4. The main channel outlet 1 is connected to the microparticle outlet orifice 7, which collects the discharged solid particles, via the microparticle outlet direct current channel 6. When the pressure source injects the solid-liquid mixture, the fluid fills the entire filter structure. A portion of the fluid entering the main channel 1 comes into contact with the filter blade assembly 2 and flows through the inter-blade channel 8 into the secondary channel 9. Finally, it enters the filtrate collector connected to the filtrate outlet orifice 11 via the filtrate outlet channel 10, completing the collection of the filtrate. When solid particles in the mixed fluid enter the flow channel 8 between the filter blades, they are moved back into the mixed fluid in the main channel 1 due to the bending of the filter blades, instead of accumulating on the bent filter blades, thus completing the self-cleaning filtration function. The mixed fluid in the main channel 1 that has not been filtered by contact with the bent filter blades and the particles returning to the main channel 1 will enter the microparticle outlet direct current channel 6 along the main channel 1 and be collected.

[0050] This invention designs a filter for screening microscale particles. The microstructure in the filter is fabricated in the form of a microfluidic chip. By adjusting the inlet flow rate (when the round solid particles are only affected by the flow field itself in the microchannel, without any other external field), it is possible to achieve efficient filtration of solid particles smaller than the minimum distance between the filter blades. This improves the filtration accuracy and efficiency for smaller solid particles when using the filter, and reduces the occurrence of filter clogging and contamination.

[0051] Specific embodiments of the present invention are as follows:

[0052] Step 1:

[0053] Fabrication of biomimetic microfluidic chips: Microchannels are fabricated using standard soft lithography. Simply put, a 60μm thick layer of negative photoresist is spin-coated onto a wafer. After baking, a mask is applied to the silicon wafer using ultraviolet light. Uncured photoresist is then removed by SU-8 developer, yielding a master mold with patterned channel structures. Next, polydimethylsiloxane (PDMS) with a base-to-curing agent ratio of 10:1 is poured onto the master mold. The mold is degassed in a vacuum chamber for 1 hour, then transferred to a 65°C oven for 2 hours to cure the PDMS. After cooling, the PDMS channels are peeled from the wafer, cut into shapes, and 1mm diameter holes are drilled at the inlet and outlet. After surface activation, the chips are bonded to glass using oxygen plasma. The chips are then placed in a 65°C oven for 2 hours to irreversibly bond them to a glass slide.

[0054] Step 2:

[0055] Preparation of solid particle suspensions: Polystyrene fluorescent particles with diameters of 10 μm, 15 μm, and 20 μm were used in the experiment. The density of all particles was 1.05 g / cm³. -3 Three different particle sizes were suspended in deionized water containing 0.5 wt% Tween 20 to prevent particle aggregation. The concentrations of 10, 15, and 20 μm particles were diluted to 1.0 × 10⁻⁶. 6 Prepare a particle suspension of 1 particle / mL and stir for 10 minutes to ensure that the particles are evenly dispersed in the solution.

[0056] Step 3:

[0057] Experimental Setup: The fabricated microfluidic chip with filter blades was clamped onto an inverted microscope. A prepared suspension of fluorescent particles was drawn into a syringe and attached to a peristaltic pump. The syringe was connected to a microtube via a needle. A thin steel tube was used to connect the microtube to the inlet orifice 5 of the microfluidic chip. Multiple experiments were conducted with varying inlet flow rates and Reynolds numbers by adjusting the peristaltic pump parameters. After observing the particles through the microscope's eyepiece, the particle motion characteristics within the biomimetic microstructure of the microfluidic chip were recorded using a high-speed camera and its built-in software. By varying the injection flow rate of the syringe pump, the filtration mechanism of the biomimetic microstructure on solid particles in the mixed solution was observed under different flow rates and Reynolds numbers using a U-shaped channel. The two outlet orifices 7 and 11 of the microfluidic chip were connected to different collection devices to collect the solution at the outlet. The number of fluorescent particles in the outlet solution was counted and compared using a hemocytometer, and the filtration efficiency under the used filter structure was further analyzed.

[0058] 3.1 Before injecting the particulate solution into the bionic filter, first fill the chip with deionized water for five minutes to clean the channels and remove air bubbles.

[0059] 3.2 Sample solutions were collected from the microparticle outlet orifice 7 and the filtrate outlet orifice 11, respectively, for particle counting and concentration characterization. The filtration efficiency of the filter is represented by η, where η = N1 / N, and N1 is the total number of particles collected from the microparticle outlet orifice 7, and N is the total number of particles collected from all outlets. The Reynolds number is calculated using the formula Re = ρU. f D h / μ, where ρ is the density of the solution, U f D is the average velocity of the solution. h Let μ be the hydraulic diameter of the channel, and μ be the dynamic viscosity of the solution. Specific Implementation Example 1

[0061] A peristaltic pump was used to drive a microfluidic chip with a filter blade structure to conduct filtration efficiency experiments. The peristaltic pump parameters were set to 0.25-8 mL / min, resulting in an inlet flow velocity of 0.35-11.11 m / s and a Reynolds number (Re) of 32-1021. The mixed solution contained fluorescent particles with a diameter of 10 μm. The fluid from the outlet section was collected, and the changes in the microfluidic chip's particle filtration efficiency (%) and inlet flow rate (mL / min) are shown in the graph below. Figure 3 As shown, particles are collected in the main channel 1 under the action of fluid inertia and vortex at the leading edge of the filter blade. The fluid flows out from the secondary channel 9 along the blade gap, thus achieving the filtration of most particles. The filtration efficiency increases with the increase of the inlet section velocity. Specific Implementation Example 2

[0063] A peristaltic pump was used to drive a microfluidic chip with a filter blade structure to conduct filtration efficiency experiments. The peristaltic pump parameters were set to 0.25-8 mL / min, resulting in an inlet flow velocity of 0.35-11.11 m / s and a Reynolds number (Re) of 32-1021. The mixed solution contained fluorescent particles with a diameter of 15 μm. The fluid from the outlet section was collected, and the changes in the microfluidic chip's particle filtration efficiency (%) and inlet flow rate (mL / min) are shown in the graph below. Figure 4 As shown, particles are collected in the main channel 1 under the action of fluid inertia and vortex at the leading edge of the filter blade. The fluid flows out from the secondary channel 9 along the blade gap, thus achieving the filtration of most particles. The filtration efficiency increases with the increase of the inlet section velocity. Specific Implementation Example 3

[0065] A peristaltic pump was used to drive a microfluidic chip with a filter blade structure to conduct filtration efficiency experiments. The peristaltic pump parameters were set to 0.25-8 mL / min, resulting in an inlet flow velocity of 0.35-11.11 m / s and a Reynolds number (Re) of 32-1021. The mixed solution contained fluorescent particles with a diameter of 20 μm. The fluid from the outlet section was collected, and the changes in the microfluidic chip's particle filtration efficiency (%) and inlet flow rate (mL / min) are shown in the graph below. Figure 5 As shown, particles are collected in the main channel 1 under the action of fluid inertia and vortex at the leading edge of the filter blade. The fluid flows out from the secondary channel 9 along the blade gap, thus achieving the filtration of most particles. The filtration efficiency increases with the increase of the inlet section velocity.

[0066] Comparing specific embodiments 1-3, when the inlet flow rate is less than 2 mL / min, the filtration efficiency of 10, 15, and 20 μm particles decreases with increasing inlet flow rate. Except for the 10 μm particle filtration efficiency, which eventually decreases to 45.90% (less than 50%), the filtration efficiency of 15 and 20 μm particles remains above 50%. When the inlet flow rate is greater than 2 mL / min, the filtration efficiency of 10, 15, and 20 μm particles increases rapidly with increasing inlet flow rate, then decreases slightly, reaching its maximum at 6 mL / min. The maximum filtration efficiencies for 10, 15, and 20 μm particles are 96.08%, 97.14%, and 87.82%, respectively. In conclusion, the flow rate threshold of this biomimetic filter is 2 mL / min. When the flow rate exceeds this threshold, the filtration efficiency increases rapidly, and the optimal operating flow rate is 6 mL / min. This filter can filter out 10-20μm solid particles from mixed solutions, especially 10-15μm particles with high filtration efficiency. At the same time, it effectively avoids the filter from being clogged and contaminated by solid particles, ensuring long-term, high-efficiency, self-cleaning, and low-cost operation. It provides a promising solution for applications that need to process large quantities of small-particle-size liquid samples in a short time.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that improvements and refinements can be made without departing from the working principle of the present invention, and these improvements and refinements should also be considered within the scope of protection of the present invention.

Claims

1. A filter for screening microscale particles, characterized in that: It includes a filter channel, an inlet channel, a microparticle outlet channel, and a filtrate outlet channel; the filter channel has a U-shaped structure, with the inlet end of the filter channel connected to the inlet channel, and the inlet channel is connected to an external pressure source for injecting solid-liquid mixed fluid into the inlet channel. The microparticle outlet channel and the filtrate outlet channel are both connected to the outlet end of the filter channel. After the solid-liquid mixed fluid is filtered by the filter channel, the solid particles and liquid in the solid-liquid mixed fluid enter the microparticle outlet channel and the filtrate outlet channel respectively, thereby completing the separation and filtration of the solid-liquid mixed fluid. The filter channel mainly consists of a filter blade inter-channel (8), a U-shaped main channel (1), and a U-shaped secondary channel (9). The secondary channel (9) is located inside the main channel (1), and the secondary channel (9) and the main channel (1) are arranged in parallel and spaced apart. A filter blade group (2) is arranged between the secondary channel (9) and the main channel (1). The filter blade group (2) is mainly formed by several bent filter blades evenly spaced along the circumference of the main channel (1). Each two adjacent bent filter blades form a filter blade inter-channel (8). Each filter blade inter-channel (8) is arranged along the circumference of the main channel (1) to form a filter blade inter-channel array. The filter blade inter-channel array and the filter blade group (2) are located in the same circumferential direction, and the filter blade inter-channel (8) and the bent filter blades are arranged alternately along the circumference. The main channel (1) and the secondary channel (9) are connected through the filter blade inter-channel (8). The inlet and outlet ends of the main channel (1) are connected to the inlet flow channel and the microparticle outlet flow channel, respectively. The outlet end of the secondary channel (9) is connected to the filtrate outlet flow channel. After the solid-liquid mixture is filtered through the filter channel, the solid particles in the fluid enter the microparticle outlet flow channel through the main channel (1), and the filtrate enters the filtrate outlet flow channel through the secondary channel (9).

2. A filter for screening microscale particles according to claim 1, characterized in that: The inlet flow channel includes an inlet circular hole (5), a steady flow channel (3), and an inlet direct flow channel (4). The inlet circular hole (5) is connected to one end of the inlet direct flow channel (4) through the steady flow channel (3), and the other end of the inlet direct flow channel (4) is connected to the inlet end of the main channel (1). The inlet circular hole (5) is externally connected to a pressure source for injecting solid-liquid mixed fluid. The steady flow channel (3) and the inlet direct flow channel (4) are used to stabilize the fluid injected into the inlet circular hole (5) so that the fluid forms a stable pipe flow state before entering the main channel (1). The microparticle outlet channel includes a microparticle outlet direct current channel (6) and a microparticle outlet circular hole (7). The outlet end of the main channel (1) is connected to the microparticle outlet circular hole (7) through the microparticle outlet direct current channel (6). The microparticle outlet circular hole (7) is used to collect the discharged solid particles. The filtrate outlet channel includes a filtrate outlet section channel (10) and a filtrate outlet circular hole (11). The outlet end of the secondary channel (9) is connected to the filtrate outlet circular hole (11) through the filtrate outlet section channel (10). The filtrate outlet circular hole (11) is connected to a filtrate collector.

3. A filter for screening microscale particles according to claim 1, characterized in that: Each of the bent filter blades is mainly formed by bending a round-headed elongated structure at one-third of its length. The bending angle of the bent filter blade at the bend is k1 = 150°~160°. The outer bending surface of the bent filter blade faces the inlet end of the filter, and the inner bending surface faces the outlet end of the filter.

4. A filter for screening microscale particles according to claim 1, characterized in that: The side of the bent filter blade closest to the main channel (1) is the leading edge (22), and the side closest to the secondary channel (9) is the trailing edge (23). When the fluid passes through the main channel (1) and the bent filter blade, a fluid vortex is generated near the leading edge (22), causing the liquid in the fluid to flow along the leading edge (22) to the trailing edge (23) of the bent filter blade, and then enter the filtrate outlet channel through the secondary channel (9).

5. A filter for screening microscale particles according to claim 1, characterized in that: The main channel (1) and the secondary channel (9) share a common center. The radius of the main channel (1) is greater than that of the secondary channel (9). The radius R2 of the main channel (1) is 5100~5300μm, and the radius R1 of the secondary channel (9) is 4400~4600μm.

6. A filter for screening microscale particles according to claim 2, characterized in that: The inlet DC channel (4), the microparticle outlet DC channel (6), and the filtrate outlet section channel (10) all adopt straight channels with the same width, and the width of the straight channels is W1 = 150~250 μm.

7. A filter for screening microscale particles according to claim 1, characterized in that: The size, shape and tilt angle of each bent filter blade in the filter blade group (2) are consistent, the spacing between each two adjacent bent filter blades is consistent, and the minimum spacing between each two adjacent bent filter blades is not less than twice the particle size of the solid particles in the solid-liquid mixture.

8. A filter for screening microscale particles according to claim 1, characterized in that: The pressure source is a peristaltic pump.

9. A filter for screening microscale particles according to claim 4, characterized in that: The angle between the leading edge (22) of the bent filter blade and the tangent of the central axis of the main channel (1) is 10°~20°.

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