Microorganism self-cleaning filtering device and application and structure optimization method thereof

Abstract

The invention discloses a microorganism self-cleaning filtering device as well as application and a structure optimization method thereof. Comprising an inlet part, a circulation part and an outlet part, each of the inlet part and the outlet part adopts a quarter-arc-shaped channel, the circulation part is formed by connecting at least two unit channels and an upper semi-arc-shaped channel in series, and each unit channel is formed by connecting a single upper semi-arc-shaped channel and a single lower semi-arc-shaped channel end to end; the circle centers of all the arc-shaped channels are collinear, and the radius of the center line of the upper semi-arc channel is larger than that of the lower semi-arc channel. The serpentine channel is divided into a main channel, an auxiliary channel and a plurality of inter-filtering-blade channels for communicating the main channel with the auxiliary channel by the filtering blade array, an inlet and an outlet of the main channel are respectively communicated with the inlet hole and the microorganism outlet hole, and an outlet of the auxiliary channel is communicated with the filtrate outlet hole. The filtering device disclosed by the invention is beneficial to realizing separation of multi-particle-size dispersed microorganisms between the main channel and the auxiliary channel, and the stability is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbial filtration, and particularly relates to a microbial self-cleaning filtration device, its application and a method for optimizing its structure. Background Art

[0002] In many fields of solid-liquid separation treatment, especially in the microbial sorting in medical technology, in the past screening and filtration devices, when high filtration efficiency, precision or long-term high-throughput operation is required, blockage usually occurs. Stopping the operation of the filtration device and replacing the screen is a common solution, but this method not only reduces efficiency but also significantly increases the operating cost. Using a bionic filtration device can effectively avoid the accumulation and blockage of pollutants on the surface of the filtration device without external force. The curved channel design adopted by some bionic filtration devices can effectively improve the filtration efficiency of the filtration device and enable the filtration device to achieve self-cleaning function when filtering tiny microorganisms, extend the working time of the filtration device, reduce the economic efficiency loss caused by stopping operation to replace components and additional personnel allocation, and has important economic and application values. However, in the prior art, there is still a lack of a bionic structure microbial filtration device to meet the actual production needs of high efficiency and long filtration time. Summary of the Invention

[0003] In order to overcome the deficiencies in the prior art, the present invention provides a microbial self-cleaning filtration device, its application and a method for optimizing its structure. The microbial self-cleaning filtration device of the present invention combines a serpentine channel composed of a specific number of unit channels connected in series and bionic filtration blades to perform coupled filtration on multi-particle-size dispersed microorganisms in a microbial culture solution.

[0004] The technical solution adopted by the present invention is as follows:

[0005] I. A microbial self-cleaning filtration device

[0006] The microbial self-cleaning filtration device includes an inlet hole, a microbial outlet hole, a filtrate outlet hole, a serpentine channel, and a filtration blade array disposed inside the serpentine channel. The serpentine channel includes an inlet portion, a circulation portion, and an outlet portion connected in sequence. The inlet portion and the outlet portion each adopt a quarter-circular arc channel, and the circulation portion is composed of at least two unit channels and a semi-circular arc channel connected in series. Each unit channel is formed by connecting a single semi-circular arc channel and a lower semi-circular arc channel end to end; the centers of all the circular arc channels are collinear, and the center line radius of the upper semi-circular arc channel is greater than that of the lower semi-circular arc channel.

[0007] Specifically, the filter blade array divides the serpentine channel into a main channel and a secondary channel, as well as several inter-filter-blade channels that connect the main channel and the secondary channel. The inlet and outlet of the main channel are respectively connected to the inlet hole and the microorganism outlet hole, and the outlet of the secondary channel is connected to the filtrate outlet hole. The inlet hole is used for injecting the microorganism culture solution to be filtered, and the microorganism culture solution includes target microorganisms.

[0008] Specifically, the filter blade array is mainly composed of several filter blades arranged at equal intervals along the center line of the serpentine channel. The filter blade adopts a bent structure, which is mainly formed by bending a round-head long-strip structure at one-third of its own length. The outer bent surface of the bent structure faces the inlet end of the filtering device, and the inner bent surface faces the outlet end of the filtering device. The bending angle at the bending part of the bent structure is 150° - 160°. The side close to the main channel in the bent structure is the leading edge, and the angle between the leading edge and the tangent of the central axis of the serpentine channel is 10° - 20°.

[0009] Preferably, the ratio of the center line radius of the lower semi-circular arc channel to that of the upper semi-circular arc channel is 87.5% - 90%.

[0010] Preferably, the particle size distribution range of the target microorganisms is 5 - 12 μm. The radial width of the serpentine channel is 700 μm - 900 μm, the radial width of the inter-filter-blade channel is 200 μm - 300 μm, and the radial widths of the main channel and the secondary channel are the same, both being 200 μm - 300 μm. The centripetal side radius and the centrifugal side radius of the upper semi-circular arc channel are 1800 μm - 2000 μm and 2500 μm - 2700 μm respectively. The centripetal side radius and the centrifugal side radius of the lower semi-circular arc channel are 1600 μm - 1800 μm and 2300 μm - 2500 μm respectively.

[0011] Preferably, the distance between every two adjacent filter blades is kept consistent, and the distance between two adjacent filter blades is greater than or equal to twice the maximum value of the particle size of the target microorganisms.

[0012] Preferably, the connection point of the centripetal side of the upper semi-circular arc channel and the centrifugal side of the adjacent lower semi-circular arc channel is tangent. The centrifugal side of the upper semi-circular arc channel and the centripetal side of the adjacent lower semi-circular arc channel are connected by a section of transition curved wall surface, and the transition curved wall surface is respectively tangent to the upper semi-circular arc channel and the lower semi-circular arc channel.

[0013] Further, the microchannel further includes a flow stabilizing channel, an inlet channel, a microbial outlet channel, and a filtrate outlet channel; the inlet hole is communicated with the inlet end of the main channel through a flow stabilizing channel and an inlet channel in sequence; the microbial outlet hole is communicated with the outlet end of the main channel through a flow stabilizing channel and a microbial outlet channel; the filtrate outlet hole is communicated with the outlet end of the auxiliary channel through a filtrate outlet channel; the inlet channel is arranged tangentially to the main channel at the inlet part of the serpentine channel; the microbial outlet channel is arranged tangentially to the main channel at the outlet part of the serpentine channel; the inlet end of the filtrate outlet channel is arranged tangentially to the outlet end of the auxiliary channel at the outlet part of the serpentine channel.

[0014] II. A Structural Optimization Method for a Microbial Self-Cleaning Filter Device

[0015] The structural optimization method includes the following steps:

[0016] S1) Preset the input pressure, the target output flow rate, and the cross-sectional dimension parameters of the serpentine channel;

[0017] The cross-sectional dimension parameters of the serpentine channel include the center line radius and the radial width of the upper semi-circular arc channel and the lower semi-circular arc channel;

[0018] S2) Obtain the centripetal side and centrifugal side radii of the upper semi-circular arc channel and the centripetal side and centrifugal side radii of the lower semi-circular arc channel according to the cross-sectional dimension parameters of the serpentine channel;

[0019] S3) Process the input pressure, the target output flow rate, the centripetal side and centrifugal side radii of the upper semi-circular arc channel, and the centripetal side and centrifugal side radii of the lower semi-circular arc channel through the following formula to obtain the number N of the upper semi-circular arc channels:

[0020]

[0021] In the formula, Q represents the target output flow rate, ΔP represents the input pressure, R 直 represents the straight pipe flow resistance, represents the single correction coefficient of a quarter circle arc, set to 0.01 - 0.05, represents the single correction coefficient of a semi-circle arc, set to 0.02 - 0.1, N represents the number of upper semi-circular arc channels, μ represents the dynamic viscosity, L represents the total channel length, L 上 represents the upper edge length, L 下 represents the lower edge length, R1 represents the centripetal side radius of the upper semi-circular arc channel, R2 represents the centrifugal side radius of the lower semi-circular arc channel, R3 represents the centripetal side radius of the lower semi-circular arc channel, and R4 represents the centrifugal side radius of the upper semi-circular arc channel.

[0022] Further, in step S3, the first formula can also be replaced with:

[0023]

[0024] In the formula, f 前 represents the correction coefficient of the filter blade, which is set to 0.1 - 0.15.

[0025] III. Application of a Microbial Self-Cleaning Filter Device

[0026] The microbial self-cleaning filter device can be used for filtering multi-particle-size dispersed microorganisms in Newtonian fluids, and the particle size distribution range of the target microorganisms is 5 - 12 μm.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. The microbial self-cleaning filter device provided by the present invention combines factors such as the enhanced effect of periodic Dean vortices, the synergistic effect of inertial lift and Dean flow, and the strengthening of the cumulative effect and equilibrium position, achieving higher stability, maintainability of high flow efficiency, etc.

[0029] 2. The microbial self-cleaning filter device provided by the present invention realizes the filtration treatment of multi-particle-size dispersed microorganisms by adopting a serpentine inertial focusing separation mechanism for focusable microorganisms and a Dean force-driven separation mechanism for non-focusable microorganisms. Description of the Drawings

[0030] Figure 1 is a schematic diagram of the microstructure of the filter device of the present invention;

[0031] Figure 2 is a schematic diagram of the structure of the filter blade of the filter device of the present invention;

[0032] Figure 3 is a schematic diagram of the filtration results of the filter devices of the examples and comparative examples of the present invention;

[0033] Figure 4 is a schematic diagram of the filtration flow ratio of the filter device of the example of the present invention;

[0034] Figure 5 is a schematic diagram of the serpentine flow channel structure of the filter device of the present invention.

[0035] In the figure, 1, main channel; 2, filter blade group; 3, flow stabilizing structure; 4, inlet channel; 5, inlet hole; 6, microorganism outlet channel; 7, microorganism outlet hole; 8, inter-filter blade channel; 9, sub-channel; 10, filtrate outlet channel; 11, filtrate outlet hole; 12, serpentine channel; 21, inlet of the inter-filter blade channel; 22, leading edge; 23, trailing edge; 24, outlet of the inter-filter blade channel. Detailed Embodiments

[0036] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form.

[0037] In a first aspect of the present invention, a microbial self-cleaning filtration device is provided. The microbial self-cleaning filtration device of the present invention divides the serpentine channel into a main channel and a secondary channel through a filter blade array. The main channel is responsible for collecting multi-size dispersed microorganisms after filtration, while the secondary channel is used to collect the filtrate. The multi-size dispersed microorganisms specifically refer to: the microbial culture solution usually includes target microorganisms in different growth stages, and the particle sizes of the target microorganisms in different growth stages are also correspondingly different. Therefore, the particle size distribution range of the target microorganisms should cover all target microorganisms in different growth stages.

[0038] In the serpentine channel, along the main flow direction, the microorganisms are subjected to a resistance force, making their velocities consistent with the fluid velocity; perpendicular to the main flow direction, the microorganisms are subjected to the combined action of the inertial lift force (F L ) and the Dean drag force (F D ), causing the microorganisms to move in the cross-section of the flow channel. The inertial lift force (F L ) causes the microorganisms to migrate from a random distribution to a specific equilibrium position in the cross-section of the channel; due to the action of the centrifugal force, the fluid with a high flow velocity will move to the outside, and the fluid with a low flow velocity on the outside is squeezed and moves to the inside, generating a Dean vortex, and the vortex will apply a Dean drag force (F D ) to the microorganisms.

[0039] Since achieving microbial focusing requires satisfying the particle size constraint ratio a / D H > 0.07, where a is the particle size of the microorganism and D H is the hydraulic diameter (in the microbial self-cleaning filtration device of the present invention, the channel adopts a rectangular cross-section structure, so D h = 2hw / (h + w), where h and w are the channel height and width respectively), therefore, for the target multi-size dispersed microorganisms, due to their wide particle size distribution, it is impossible to satisfy the focusing of all particle size microorganisms under fixed geometric parameters.

[0040] Therefore, in the method of the present invention, for the microorganisms that can be focused, the serpentine inertial focusing separation mechanism is mainly adopted; for the microorganisms that cannot be focused, the Dean force-driven separation mechanism is mainly adopted.

[0041] The serpentine inertial focusing separation mechanism specifically refers to: the serpentine inertial focusing separation mechanism is realized through the movement of microorganisms in the dynamic balance process of the inertial lift force (F L ) and the Dean drag force (F D ). The microorganisms in the main and secondary channels will be in the inertial lift force (F L ) and the Dean drag force (FD ) moves a distance L under the action of f to their respective equilibrium positions to achieve focusing. Focusing is beneficial to increasing the density of microorganisms. By adjusting the Dean drag force (F D ), the trajectory can be changed, and combined with the synergistic effect of the bionic filter blade, a large number of microorganisms can be separated.

[0042] The Dean vortices generated by the serpentine channel will form vortices at the trailing edge of the bionic filter blade. When microorganisms approach the vortices, they will be subjected to suction force and then enter the main channel from the flow channels between the blades, improving the filtration efficiency. Microorganisms near the leading edge of the filter blade in the main channel will collide with the blade under the action of the vortex at the leading edge of the blade, bounce back to the "main channel" under the contact force, and then move towards the centripetal side under the Dean force brought by the "secondary flow", inhibiting the microorganisms from entering the sub-channel and avoiding the reduction of efficiency. The "attraction - inhibition" dual mechanism effectively improves the filtration efficiency. Through the continuous and alternating curvature changes of the serpentine channel, the Dean vortices are re-excited and superimposed after each bend, forming a periodic strengthening effect. The strengthening of the Dean vortices will lead to the enhancement of the Dean force, enabling the unfocused microorganisms to accelerate and move to the equilibrium position, improving the focusing efficiency. Since the velocity of the fluid around the microorganisms is relatively low, the gradually increasing Dean force along the flow channel will cause the focused microorganisms to move towards the centripetal side, that is, the microorganisms in the sub-channel will be closer to the blade, which is more conducive to separation. The strengthening effect of the Dean force in the serpentine channel and the "focusing - attraction - inhibition" mechanism formed by the flow channel and the blade effectively enhance the filtration efficiency.

[0043] Specifically, the Dean force-driven separation mechanism refers to: The Dean force-driven separation mechanism is based on the change and enhancement of the Dean force generated by the continuous and alternating curvature changes of the serpentine channel. For those microorganisms with small particle sizes that cannot be focused, the action of the Dean force on them is much greater than that of the inertial lift force. Therefore, by changing the direction of the Dean force, the separation of some microorganisms can be achieved. When in the upper semi-circular arc region, for the microorganisms relatively close to the blade periphery, due to the relatively slow flow velocity around the microorganisms, they are subjected to the Dean force and move towards the centripetal direction, and further enter the main channel through the flow channels between the blades to achieve primary separation. When entering the lower semi-circular arc region, the faster microorganisms are subjected to the Dean force and move centrifugally, approach the blade, and enter the main channel under the action of the vortex between the blades to achieve secondary separation. Due to the periodic and continuous change of the curvature of the serpentine channel, the Dean force has a periodic strengthening property and will gradually increase along the flow channel, resulting in a more significant separation effect for the microorganisms in the latter half of the flow channel.

[0044] Such as Figure 1As shown, the microbial self-cleaning filtration device includes an inlet hole 5, a microbial outlet hole 7, a filtrate outlet hole 11, a serpentine channel 12, and a filter blade array 2 disposed inside the serpentine channel 12; the serpentine channel 12 includes an inlet portion, a circulation portion, and an outlet portion connected in sequence. The inlet portion is a right-lower quarter-circular channel, the circulation portion is formed by connecting at least two unit channels and an upper semi-circular channel in series, each unit channel is formed by connecting a single upper semi-circular channel and a single lower semi-circular channel end to end, and the outlet portion is a left-lower quarter-circular channel; the inlet portion is communicated with the inlet hole 5, and the outlet portion is respectively communicated with the microbial outlet hole 7 and the filtrate outlet hole 11; the centers of all the circular channels (including the complete semi-circular channels and the quarter-circular channels) are arranged collinearly, and the center line radius of the upper semi-circular channel is greater than that of the lower semi-circular channel.

[0045] The filter blade array 2 divides the serpentine channel 12 into a main channel 1 and a secondary channel 9, and several filter blade inter-channel passages 8 that communicate the main channel 1 and the secondary channel 9. The main channel 1 is located on the side close to the lower semi-circular channel, the secondary channel 9 is located on the side close to the upper semi-circular channel, and a filter blade inter-channel passage 8 is formed between every two adjacent filter blades; the inlet and outlet of the main channel 1 are respectively communicated with the inlet hole 5 and the microbial outlet hole 7, and the outlet of the secondary channel 9 is communicated with the filtrate outlet hole 11.

[0046] The inlet hole 5 is used to inject the microbial culture solution to be filtered, and the microbial culture solution includes the target microorganisms.

[0047] The microbial outlet hole 7 is used to discharge the solution containing microorganisms.

[0048] The filtrate outlet hole 11 is used to discharge the filtrate.

[0049] Specifically, the filter blade array 2 is mainly formed by arranging several filter blades at equal intervals along the center line of the serpentine channel 12; the filter blades adopt a bent structure, and the bent structure is mainly formed by bending a round-headed long strip structure at one-third of its own length. The outer bent surface of the bent structure faces the inlet end of the filtration device, and the inner bent surface faces the outlet end of the filtration device.

[0050] Preferably, the bending angle of the bent structure at the bending position is 150° - 160°; the side of the bent structure close to the main channel 1 is the leading edge 22, the side close to the secondary channel 9 is the trailing edge 23, and the angle between the leading edge 22 and the tangent of the central axis of the serpentine channel 12 is 10° - 20°.

[0051] Preferably, the distance between every two adjacent filter blades is kept consistent, and the distance between two adjacent filter blades is greater than or equal to twice the maximum value of the particle size of the target microorganisms.

[0052] Preferably, on the basis of the above-described embodiment, when the particle size distribution range of the target microorganism is 5-12 μm, the ratio of the center line radius of the lower semi-circular arc channel to the upper semi-circular arc channel is 87.5%.

[0053] Preferably, on the basis of the above-described embodiment, when the particle size distribution range of the target microorganism is 5-12 μm, the radial width of the serpentine channel 12 is 700 μm to 900 μm, the radial width of the channel 8 between the filter vanes is 200 μm to 300 μm, and the radial widths of the main channel (1) and the auxiliary channel (9) are the same, both being 200 μm to 300 μm. For microorganisms with weak focusing ability, their lift force is small, and it is necessary to reduce the Dean force and increase the curvature radius to achieve focusing; for microorganisms with strong focusing ability, the lift force is large, and it is necessary to enhance the Dean force and reduce the curvature radius to improve the trajectory mobility. To improve the filtration efficiency and practicality, the appropriate radius should be accurately set according to the characteristics of the microorganisms. Therefore, the size parameters of the circular arc channels are set as follows: the centripetal side radius and the centrifugal side radius of the upper semi-circular arc channel are 1800 μm to 2000 μm and 2500 μm to 2700 μm respectively; the centripetal side radius and the centrifugal side radius of the lower semi-circular arc channel are 1600 μm to 1800 μm and 2300 μm to 2500 μm respectively.

[0054] Preferably, the connection point between the centripetal side of the upper semi-circular arc channel and the centrifugal side of the adjacent lower semi-circular arc channel is tangent (i.e., tangent connection); the centrifugal side of the upper semi-circular arc channel and the centripetal side of the adjacent lower semi-circular arc channel are connected by a section of transition curved wall surface, and the transition curved wall surface is tangent to the upper semi-circular arc channel and the lower semi-circular arc channel respectively. The transition curved wall surface being tangent to the upper semi-circular arc channel and the lower semi-circular arc channel respectively specifically means that the projection of the transition curved wall surface on the base surface is a transition curve, and the two ends of the transition curve are tangent to the projection of the upper semi-circular arc channel and the projection of the lower semi-circular arc channel respectively. By setting the transition curved wall surface, not only can the radius of the trajectory line of the filter vane group be ensured to be consistent, the main and auxiliary channels be separated evenly, so that a constant pressure gradient field is formed between the main / auxiliary channels, but also the energy loss of the inertial focusing fluid can be significantly reduced through the gradual change of curvature, realizing the laminar flow smooth turning of the microorganisms. In addition, this tangent connection method can avoid the formation of dead zones, reduce the retention of pollutants, and is suitable for long-term continuous separation operations of high-viscosity culture media.

[0055] Further, the microchannel further includes a flow-stabilizing channel 3, an inlet channel 4, a microorganism outlet channel 6, and a filtrate outlet channel 10; the inlet hole 5 is sequentially communicated with the inlet end of the main channel 1 through a flow-stabilizing channel 3 and an inlet channel 4; the microorganism outlet hole 7 is communicated with the outlet end of the main channel 1 through a flow-stabilizing channel 3 and a microorganism outlet channel 6; the filtrate outlet hole 11 is communicated with the outlet end of the auxiliary channel 9 through the filtrate outlet channel 10; the inlet channel 4 is tangentially arranged with the main channel 1 at the inlet part of the serpentine channel 12; the microorganism outlet channel 6 is tangentially arranged with the main channel 1 at the outlet part of the serpentine channel 12; the inlet end of the filtrate outlet channel 10 is tangentially arranged with the outlet end of the auxiliary channel 9 at the outlet part of the serpentine channel 12.

[0056] Further, the microorganism self-cleaning filtration device is mainly formed by connecting a base and a channel layer; an inlet hole 5, a microorganism outlet hole 7, and a filtrate outlet hole 11 are formed in the channel layer; a microchannel structure and a micro-vane array structure are arranged on the surface of the channel layer close to the base side, the microchannel structure and the base enclose to form a microchannel, and the micro-vane array structure and the base enclose to form a filtration vane array 2.

[0057] When the microorganism self-cleaning filtration device of the present invention is used for microorganism filtration: the microorganism culture solution to be filtered first enters the inlet part (the lower right quarter arc area) of the serpentine channel through the inlet hole 5. In the curved flow channel, the microorganism is simultaneously affected by the combined action of the Dean secondary flow force and the inertial lift force. Since the particle size of the microorganism is small and the movement distance is limited, the inertia-dominated lateral migration is not fully established, and at this time, the Dean force plays a dominant role. At this time, the Dean vortex drives the microorganism to migrate to the centrifugal side. According to the velocity distribution of the Poiseuille flow, the fluid velocity near the inner side is lower, and the particle concentration carried by it is significantly lower than that in the high-speed area. The low-speed fluid flows toward the centripetal side, while the high-concentration particles are enriched on the centrifugal side, thereby forming a two-phase concentration gradient and realizing the preliminary separation based on the spatial site difference.

[0058] Subsequently, the serpentine channel generates a periodic secondary flow, forming a periodic strengthening effect: along the serpentine channel, the Dean force gradually increases. For microorganisms with large particle sizes and strong inertia forces, better manipulation effects can be achieved, and better filtration effects can be realized through the coupling action with the filtration vanes; for microorganisms with small particle sizes and weak inertia forces, more significant filtration effects can be realized according to the Dean force-driven separation mechanism. Thus, in the serpentine channel, the focusing speed of the microorganisms is accelerated, thereby further improving the utilization rate of the flow channel separation. In addition, the serpentine channel can also ensure a stable output of the Dean force, avoiding the situation of Dean force attenuation at the end of the flow channel. During the filtration process, the serpentine structure homogenizes the flow field through multiple bends, reducing local turbulent disturbances. Making the overall filtration more stable. For example, in the embodiment of the present invention, the output flow ratio can be stably within the range of 0.598 to 0.627.

[0059] In a second aspect of the present invention, a method for optimizing the structure of the above-mentioned microbial self-cleaning filtration device is provided.

[0060] The structure optimization method includes the following steps:

[0061] S1) Preset the input pressure, target output flow rate, and cross-sectional dimension parameters of the serpentine channel 12;

[0062] The cross-sectional dimension parameters of the serpentine channel 12 include the center line radius and radial width of the upper semi-circular arc channel and the lower semi-circular arc channel;

[0063] S2) Obtain the centripetal side radius and centrifugal side radius of the upper semi-circular arc channel and the centripetal side radius and centrifugal side radius of the lower semi-circular arc channel according to the center line radius and radial width of the upper semi-circular arc channel and the lower semi-circular arc channel;

[0064] S3) Process the input pressure, target output flow rate, centripetal side radius and centrifugal side radius of the upper semi-circular arc channel, and centripetal side and centrifugal side radius of the lower semi-circular arc channel through the following formula to obtain the number N of the upper semi-circular arc channels:

[0065]

[0066] In the formula, Q represents the target output flow rate, ΔP represents the input pressure, R 直 represents the straight pipe flow resistance, represents the single correction coefficient of a quarter circle arc, set to 0.01 - 0.05, represents the single correction coefficient of a semi-circle arc, set to 0.02 - 0.1, N represents the number of upper semi-circular arc channels, μ represents the dynamic viscosity, L represents the total channel length, L 上 represents the upper edge length, L 下 represents the lower edge length, R1 represents the centripetal side radius of the upper semi-circular arc channel, R2 represents the centrifugal side radius of the lower semi-circular arc channel, R3 represents the centripetal side radius of the lower semi-circular arc channel, and R4 represents the centrifugal side radius of the upper semi-circular arc channel.

[0067] Further, in step S3, the first formula can be replaced by:

[0068]

[0069] In the formula, f 前 represents the correction coefficient of the filter blade, set to 0.1 - 0.15.

[0070] According to this structural optimization method, combined with actual conditions and requirements, the number of unit channels in the fluid part of the serpentine flow channel can be set reasonably. For the microbial self-cleaning filtration device of the present invention, in order to ensure that particles are fully focused in the serpentine flow channel, the number of unit channels n≥2, and the number of upper semi-circular arc channels N≥3.

[0071] Optionally, the center line radii of the upper semi-circular arc channel and the lower semi-circular arc channel can also be determined according to parameters such as the critical flow velocity and the particle size distribution of the target microorganism according to the following formula:

[0072]

[0073] In the formula, L f is the path length that the microorganism needs to pass through to reach the equilibrium state, μ is the dynamic viscosity, ρ is the density of the fluid, U m is the characteristic velocity, a is the particle size of the microorganism, f L is a correction coefficient that varies between 0.02 and 0.05 as the aspect ratio (H / W) changes from 2 to 0.5, and H is the width of the channel in the particle migration direction.

[0074] The third aspect of the present invention provides an application of the above-mentioned microbial self-cleaning filtration device. The microbial self-cleaning filtration device is used for filtering multi-size dispersed microorganisms in Newtonian fluid, and the particle size distribution range of the target microorganism is 5-12 μm.

[0075] The process of this application is specifically as follows: Use a syringe pump to inject the microbial culture solution to be filtered from the inlet hole 5 into the filtration device. After being filtered by the serpentine channel 12, the microbial solution containing the target microorganism flows into the microbial collection device from the microbial outlet hole 7, and the clear liquid flows into the waste liquid collection device from the filtrate outlet hole 11.

[0076] The specific embodiments of the present invention are as follows:

[0077] Embodiment

[0078] This embodiment provides a microbial self-cleaning filtration device for coupled filtration of yeast (particle size distribution range 5-12 μm).

[0079] In the microbial self-cleaning filtration device of this embodiment, the substrate is a glass slide, and the channel layer is prepared by pouring and molding polydimethylsiloxane (PDMS). The micro-vane array structure of the channel layer is formed by arranging 128 filter vanes with exactly the same shape at intervals along the central axis of the serpentine channel 12.

[0080] As Figure 2As shown in the figure, in the filter blade of this embodiment, the side close to the main channel 1 is the leading edge 22 of the bent filter blade (the arc-shaped cross-section part between the blade edges with lengths L1 and L4), and the side close to the sub-channel is the trailing edge 23 of the bent filter blade (the arc-shaped cross-section part between the blade edges with lengths L2 and L3). The angle of the bent part is k1 = 156°, and the side lengths are L1 = 172 μm, L2 = 323 μm, L3 = 297 μm, and L4 = 148 μm respectively. The radii of the leading edge 22 and the trailing edge 23 are R5 = 40 μm and R6 = 40 μm respectively. The side of the filter blade with length L1 is arranged to contact the main channel. The smaller angle k2 between the tangent of the filter blade and the symmetry center line of the main channel is 13°, and the opening direction of the angle faces the inlet side. The radial width of the channel 8 between the filter blades is 300 μm. The minimum distance W2 between adjacent inter-blade channels is 43 μm. The side of the channel 8 between the filter blades close to the main channel 1 is the inlet 21 of the channel between the filter blades, and the side close to the sub-channel 9 is the outlet 24 of the channel between the filter blades. The liquid in the mixed fluid flows from the inlet 21 of the channel between the filter blades to the outlet 24 of the channel between the filter blades.

[0081] In the microchannel of this embodiment, the inlet channel 4, the microorganism outlet channel 6, and the filtrate outlet hole 11 all adopt straight channels with a width of W1 = 150 μm. The numbers of the upper semi-circular arc channels and the lower semi-circular arc channels are 3 and 2 respectively; the radii of the center lines of the upper semi-circular arc channels and the lower semi-circular arc channels are 2163.5 μm and 1908 μm respectively; the radial width of the serpentine channel 12 is 700 μm. As Figure 5 shown, the inner radius R1 of the centripetal side radius bending direction and the outer radius R4 of the centrifugal side radius bending direction of the upper semi-circular arc channel are 1845 μm and 2550 μm respectively; the inner radius R3 of the centripetal side radius bending direction and the outer radius R2 of the centrifugal side radius bending direction of the lower semi-circular arc channel are 1660 μm and 2300 μm respectively. The cross-sectional width w of the main channel 1 and the sub-channel 9 is 200 μm, and the height of the serpentine channel is h = 100 μm.

[0082] In the filter device of this embodiment, standard soft lithography technology is used to prepare the microchannel structure and the microblade array structure. The filter device is specifically prepared by the following steps: a layer of negative photoresist with a thickness of 60 μm is spin-coated on the wafer. After baking, the mask is covered on the silicon wafer by ultraviolet irradiation. Then it is placed in SU-8 developer to remove the uncured photoresist to obtain a master mold with a patterned channel structure. Polydimethylsiloxane (PDMS) configured with a base and a curing agent in a ratio of 10:1 is fully stirred and mixed in a high-speed centrifugal mixer and poured onto the master mold. The mold is degassed in a vacuum chamber for 1 hour and then transferred to an oven at 65°C for 2 hours to cure the PDMS. After cooling, the PDMS channel is peeled off the wafer, cut into shape, holes with a diameter of 1 mm are punched at the inlet and outlet, and bonded to the glass with oxygen plasma after surface activation. The chip is then placed in an oven at 65°C for 2 hours to irreversibly bond the chip to the glass slide.

[0083] Comparative Example

[0084] This comparative example provides a microbial self-cleaning filtration device for coupled filtration of yeast (particle size distribution range 5-12 μm). The microbial self-cleaning filtration device comprises a single semicircular arc channel provided with a filter blade array. The radius of the semicircular arc channel is 5000 μm.

[0085] Next, the present invention uses the microbial self-cleaning filtration device in the embodiment and the comparative example to filter the yeast culture solution. During the filtration process, a common laboratory syringe pump with a maximum linear output force of 195N is used to inject the yeast culture solution to be filtered with a common syringe tube with a diameter of 20mm. During the filtration process, the syringe pump output is set to 0.25-7mL / min.

[0086] The specific filtration process is as follows: take a sterilized and clean test tube, add 40g of 35°C warm water, 0.0226g of highly active yeast powder, and configure the microbial concentration to 3.0×10 6A yeast mixed solution of about cells / mL was placed in a constant-temperature vortex shaker and shaken for 15 minutes to evenly disperse the yeast in the solution. First, the filtration device was clamped on an inverted microscope. Before injecting the microbial solution into the filtration device, the microbial self-cleaning filtration device was perfused with deionized water for five minutes to clean the channels and remove air bubbles. Then, the prepared yeast mixed solution was drawn into a syringe, which was clamped to an injection pump. The syringe was connected to the microtube through a needle; the microtube was connected to the inlet hole 5 with a thin steel tube, and the parameters of the injection pump were adjusted to conduct multiple groups of experiments at different flow rates. After observing the yeast through the eyepiece attached to the microscope, the movement characteristics of the yeast in the filtration device were photographed and recorded by a high-speed camera and its accompanying software. By changing the injection flow rate of the injection pump, the filtration mechanism of the bionic microstructure on the microorganisms in the mixed solution was observed under different flow rate conditions after adopting the serpentine channel. The target microorganism outlet hole 7 and the filtrate outlet hole 11 of the microbial self-cleaning filtration device were respectively connected to different collection devices for collecting the solution at the outlet. The number of microorganisms in the outlet solution was counted and compared using a hemocytometer, and the filtration efficiency under the used microbial self-cleaning filtration device was further analyzed.

[0087] For the sample solutions collected from the target microorganism outlet hole 7 and the filtrate outlet hole 11, microbial counting and concentration characterization were performed. The filtration efficiency of the filtration device is represented by η, η = N1 / N, where N1 is the total number of microorganisms collected from the microorganism outlet hole 7, and N is the total number of microorganisms collected from all outlets. The flow ratio of the filtration device is represented by Q, Q = ΔM1 / ΔM, where ΔM1 is the mass of the fluid collected from the target microorganism outlet hole 7, and ΔM is the total mass of the fluid collected from all outlets.

[0088] Driven by an injection pump, a filtration efficiency experiment was conducted on the filtration device. During the experiment, the parameters of the injection pump were set to 0.25 - 7 mL / min, and the microbial filtration efficiency (%) and input flow rate (mL / min) of the microbial self-cleaning filtration device were obtained by collecting the fluid in the outlet section.

[0089] The results of microbial filtration using the filtration devices in the examples and comparative examples are as Figure 3 shown. The graph of the change in the filtration flow ratio with the input flow rate (mL / min) for microbial filtration using the filtration device in the example is as Figure 4 shown.

[0090] From Figure 3 and Figure 4From the filtration results of the filtration device in the embodiment, it can be seen that microorganisms are aggregated in the main channel 1 under the action of fluid inertia and vortices at the bent leading edge of the filtration blades. The fluid flows out from the sub-channel 9 along the blade gap, realizing the filtration of most microorganisms. The filtration efficiency increases with the increase of the input flow rate, and the flow ratio decreases with the increase of the input flow rate. Specifically: when the inlet flow rate is less than 1 mL / min, the filtration efficiency of yeast first rapidly decreases from 59.12% with the increase of the inlet flow rate and then fluctuates between 56% and 57%. When the inlet flow rate is greater than 1 mL / min, the filtration efficiency of yeast rapidly increases with the increase of the inlet flow rate, then experiences a small decrease and then slowly rises to the maximum value. The maximum filtration efficiency reaches the maximum value at 7 mL / min, and the maximum filtration efficiency is 77.49%.

[0091] When the flow rate is less than 0.75 mL / min, the flow ratio continuously decreases from the maximum value of 0.6277 under the condition of 0.25 mL / min. After the flow rate is greater than 0.75 mL / min, it rises to the peak value of 0.6224 under the condition of 3 mL / min and then continuously decreases until the minimum value of 0.5969 under the condition of 7 mL / min. Generally, it can be considered that the flow ratio of the filtration device in the embodiment is stable at about 0.61, and the flow ratio decreases with the increase of the flow rate.

[0092] In addition, by comparing the results of the embodiment and the comparative example, it can be seen that the performance of the embodiment is significantly optimized in the high-flow region compared with the comparative example, and the standard deviation of the full flow rate is significantly reduced, further indicating that the serpentine multi-bend design significantly improves the filtration performance and stability of the microbial self-cleaning filtration device. Specifically:

[0093] ① The performance in the high-flow region is significantly optimized

[0094] A. The critical flow rate shifts to the left: The efficiency of the embodiment exceeds that of the comparative example at 2 mL / min (64.9% vs 60.5%), indicating that multiple bends with a smaller radius of curvature reduce the flow rate threshold of inertial focusing.

[0095] B. The growth advantage of high-flow efficiency: In the range of 5 - 7 mL / min, the efficiency growth rate of the embodiment (1.95% / mL) is 2.8 times that of the comparative example (0.69% / mL), verifying the continuous regulation effect of multiple bends on the flow field.

[0096] ② The stability is enhanced: The standard deviation of the full flow rate is significantly reduced

[0097] A. Suppression of fluctuations in the low-flow region: At 0.5 mL / min, the standard deviation of the embodiment is only 1.48 (A is 7.61), with a decrease of 80.6%, due to the homogenization of the inlet disturbance by the serpentine structure.

[0098] B. High-flow region stability maintenance: At 7 mL / min, the standard deviation of the example is 2.55, still lower than 3.58 of the comparative example, indicating that the multi-bend design reduces the random pulsation of the flow field;

[0099] C. In the medium-high flow rate range (2 - 7 mL / min), the filtration efficiency of the example is increased by up to 4.4% compared with the comparative example.

[0100] D. The average standard deviation of the full flow rate is reduced by 62.4%, indicating the advantage of its flow field uniformity.

[0101] In summary, the filtration device of the present invention balances efficiency (>73% @ 5 - 7 mL / min) and stability (standard deviation <2.66) in high-throughput biological detection scenarios, providing a promising solution for applications that require processing a large amount of microbial sample liquids with a wide range of particle sizes in a short time.

[0102] The above are only the preferred embodiments of the present invention. It should be pointed out that: without departing from the working principle of the present invention, improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A microbial self-cleaning filtration device, characterized in that: It comprises an inlet hole (5), a microorganism outlet hole (7), a filtrate outlet hole (11), a serpentine channel (12), and a filtering blade array (2) arranged inside the serpentine channel (12); The serpentine channel (12) comprises an inlet, a circulation part and an outlet connected in sequence, wherein the inlet and the outlet each adopt a quarter circular arc channel, the circulation part is formed by at least two unit channels and an upper semicircular arc channel connected in series, and each unit channel is formed by a single upper semicircular arc channel and a lower semicircular arc channel connected end to end; the centers of all the circular arc channels are collinear, and the centerline radius of the upper semicircular arc channel is larger than that of the lower semicircular arc channel; The filtering blade array (2) divides the serpentine channel (12) into a main channel (1) and a secondary channel (9), and a plurality of filtering blade inter-channels (8) that connect the main channel (1) and the secondary channel (9); the inlet and outlet of the main channel (1) are connected to an inlet hole (5) and a microorganism outlet hole (7) respectively, and the outlet of the secondary channel (9) is connected to a filtrate outlet hole (11); the inlet hole (5) is used to inject a microorganism culture solution to be filtered, wherein the microorganism culture solution includes target microorganisms.

2. The microbial self-cleaning filter device according to claim 1, characterized in that: The filter blade array (2) is mainly composed of a plurality of filter blades arranged evenly at intervals along the center line of the serpentine channel (12); the filter blades adopt a bent structure, which is mainly formed by bending a round-headed long strip structure at one-third of itself, with the outer bending surface of the bent structure facing the inlet end of the filter device and the inner bending surface facing the outlet end of the filter device; the bending angle of the bent structure at the bending point is 150° to 160°; the side of the bent structure close to the main channel (1) is the front edge (22), and the angle between the front edge (22) and the tangent of the central axis of the serpentine channel (12) is 10° to 20°.

3. The microbial self-cleaning filter device according to claim 2, characterized in that: The centerline radius ratio of the lower semicircular arc channel to the upper semicircular arc channel is 87.5% to 90%.

4. The microbial self-cleaning filter device according to claim 2, characterized in that: The particle size distribution range of the target microorganisms is 5 to 12 μm; the radial width of the serpentine channel (12) is 700 μm to 900 μm, the radial width of the channel between the filter blades (8) is 200 μm to 300 μm, and the radial widths of the main channel (1) and the secondary channel (9) are consistent, both of which are 200 μm to 300 μm; the centripetal radius and the centrifugal radius of the upper semicircular channel are 1800 μm to 2000 μm and 2500 μm to 2700 μm, respectively; the centripetal radius and the centrifugal radius of the lower semicircular channel are 1600 μm to 1800 μm and 2300 μm to 2500 μm, respectively.

5. The microbial self-cleaning filter device according to claim 3 or 4, characterized in that: The distance between every two adjacent filter blades is kept consistent, and the distance between two adjacent filter blades is greater than or equal to twice the maximum particle size of the target microorganism.

6. The microbial self-cleaning filter device according to claim 1, characterized in that: The centripetal side of the upper semicircular arc channel is tangent to the connection point of the centrifugal side of the adjacent lower semicircular arc channel; the centrifugal side of the upper semicircular arc channel is connected to the centripetal side of the adjacent lower semicircular arc channel through a transition curved wall surface, and the transition curved wall surface is tangently connected to the upper semicircular arc channel and the lower semicircular arc channel respectively.

7. The microbial self-cleaning filter device according to claim 1, characterized in that: The microchannel further comprises a steady flow channel (3), an inlet channel (4), a microorganism outlet channel (6) and a filtrate outlet channel (10); the inlet hole (5) is connected to the inlet end of the main channel (1) through a steady flow channel (3) and an inlet channel (4) in sequence; the microorganism outlet hole (7) is connected to the outlet end of the main channel (1) through a steady flow channel (3) and a microorganism outlet channel (6); the filtrate outlet hole (11) is connected to the outlet end of the secondary channel (9) through the filtrate outlet channel (10); the inlet channel (4) is arranged tangent to the main channel (1) at the inlet of the serpentine channel (12); the microorganism outlet channel (6) is arranged tangent to the main channel (1) at the outlet of the serpentine channel (12); the inlet end of the filtrate outlet channel (10) is arranged tangent to the outlet end of the secondary channel (9) at the outlet of the serpentine channel (12).

8. A structural optimization method applied to the microbial self-cleaning filter device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1) presetting input pressure, target output flow rate, and cross-sectional dimension parameters of the serpentine channel (12); The cross-sectional dimension parameters of the serpentine channel (12) include the centerline radius and radial width of the upper semicircular arc channel and the lower semicircular arc channel; S2) according to the cross-sectional dimension parameters of the serpentine channel (12), obtaining the centripetal and centrifugal radii of the upper semicircular arc channel and the centripetal and centrifugal radii of the lower semicircular arc channel; S3) The number N of upper semicircular channels is obtained by processing the input pressure, the target output flow rate, the centripetal and centrifugal radii of the upper semicircular channel, and the centripetal and centrifugal radii of the lower semicircular channel through the following formula: In the formula, Q represents the target output flow, ΔP represents the input pressure, and R 直 represents the straight pipe flow resistance, Indicates the single correction coefficient of a quarter arc, set to 0.01~0.05, It represents the single correction coefficient of the semicircular arc, which is set to 0.02~0.1, N represents the number of upper semicircular arc channels, μ represents the dynamic viscosity, L represents the total length of the channel, L 上 Indicates the length of the upper edge, L 下 represents the lower edge length, R1 represents the centripetal radius of the upper semicircular channel, R2 represents the centrifugal radius of the lower semicircular channel, R3 represents the centripetal radius of the lower semicircular channel, and R4 represents the centrifugal radius of the upper semicircular channel.

9. The structural optimization method according to claim 8, characterized in that: In step S3, the formula is replaced by: In the formula, f 前 Indicates the correction coefficient of the filter blades, set to 0.1~0.

15.

10. An application of the microbial self-cleaning filtration device according to any one of claims 1 to 7, characterized in that: Used for filtering multi-size dispersed microorganisms in Newtonian fluids, the particle size distribution range of the target microorganisms is 5 to 12 μm.

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