A suspension side flow filtration device and a side flow filtration method

Abstract

In biomedical research and clinical diagnosis practice, suspension is widely used as a basic sample carrier. In the storage and transfer process, the viscosity of the suspension often presents a nonlinear growth characteristic with the accumulation of processing time, and its variation range may span several orders of magnitude. The present application provides a suspension side flow filtration device and a side flow filtration method. Through the connection structure of the bidirectional liquid driving unit and the specific pipeline, the liquid forward and reverse flow is realized, the pressure difference is dynamically adjusted to adapt to the change of the suspension viscosity, the filter membrane blockage is effectively avoided, and the stable flow rate is maintained. The present application has the advantages of preventing filter membrane blockage, adapting to the dynamic change of suspension viscosity, improving sample processing efficiency and system stability.

Description

Technical Field

[0001] This application relates to biomedical sample processing technology, specifically to a suspension sideflow filtration and collection device and a sideflow filtration and collection method. Background Technology

[0002] In biomedical research and clinical diagnostic practice, suspensions are widely used as basic sample carriers, containing abundant nano- or micron-sized biological particles, such as cells and viruses. The precise separation and collection of these particles directly affects the accuracy of early disease screening, the efficiency of targeted drug development, and the depth of basic life science research. However, during storage and transfer, the physicochemical properties of suspensions are highly susceptible to the effects of time, environmental temperature fluctuations, and the continuous action of bioactive substances, leading to significant and unpredictable changes in sample state. Of particular concern is that, with accumulated processing time, the viscosity of suspensions often exhibits a non-linear growth characteristic, with changes potentially spanning multiple orders of magnitude. This dramatic viscosity change primarily stems from dynamic interactions between particles, including intensified particle aggregation, accelerated sedimentation, and ongoing biochemical reactions. This rapid increase in viscosity poses a severe challenge to traditional filtration and collection technologies: filter membrane pores become clogged with particles within a short time, abnormally increasing flow resistance and significantly reducing sample processing rates. Simultaneously, severe and uncontrollable internal pressure fluctuations not only easily lead to equipment malfunctions but also potential cross-contamination of samples, seriously affecting the reliability and reproducibility of experimental data. To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0003] The purpose of this application is to provide a suspension side-flow filtration and sampling device and a side-flow filtration and sampling method, which have the advantages of preventing filter membrane clogging, improving sample processing efficiency and system stability.

[0004] This application provides a side-flow filtration and sampling device for suspensions, the technical solution of which is as follows: A side-flow filtration and sampling device for a suspension includes a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a first sample storage unit, a second sample storage unit, a bidirectional liquid displacement unit, and a side-flow filtration and sampling unit. The sideflow filtration unit also includes an inner cavity and a hydrophilic membrane, which divides the inner cavity into a pre-membrane cavity and a post-membrane cavity. The first sample storage unit includes a first port and a second port. The side-flow filtration unit includes a third port and a fourth port. The second sample storage unit includes a fifth port and a sixth port. The bidirectional fluid drive unit includes a seventh port and an eighth port. The eighth port is connected to the first port through the first conduit. The second port is connected to the third port via a second conduit. The fourth port is connected to the fifth port via the third conduit. Port 6 is connected to Port 7 via Pipe 4. There is no switching valve installed on the second and third pipelines. A switching valve is installed on the first pipeline and / or the fourth pipeline.

[0005] Furthermore, this application also proposes that the bidirectional liquid-driving unit includes a first three-way valve, a second three-way valve, and a bidirectional air pump. The two outlets of the two-way air pump are respectively connected to the normally open ends of the first three-way valve and the second three-way valve. The common port of the first three-way valve is connected to the first pipeline. The common port of the second three-way valve connects to the fourth pipeline. The normally closed ports of the first three-way valve and the second three-way valve are respectively connected to normal pressure.

[0006] Furthermore, this application also proposes that the side-flow filtration and sampling device further includes a first liquid level detection unit and a second liquid level detection unit. And / or, the sideflow filtration and sampling device also includes a first pressure sensor, And / or, the sideflow filtration and sampling device also includes a second pressure sensor, And / or, the side-flow filtration and sampling device also includes a flow detection unit. And / or, the sideflow filtration and sampling device also includes a blocking unit.

[0007] Furthermore, this application also proposes that the first liquid level detection unit is disposed on the second pipeline, and the second liquid level detection unit is disposed on the third pipeline; And / or, the first pressure sensor is directly connected to the first sample storage unit; And / or, the second pressure sensor is directly connected to the second sample storage unit; And / or, the flow detection unit is used to detect the flow rate exiting the post-membrane cavity; And / or, the blocking unit is located on the second pipeline.

[0008] Furthermore, this application also proposes a sideflow filtration and sampling method for a sideflow filtration and sampling device, the sideflow filtration and sampling method including a pressure equalization step and a pressure increase step. The sidestream filtration method includes a recovery step.

[0009] Furthermore, this application also proposes that the execution parameters remain unchanged during the equalization pressure step. And / or, depending on the condition parameters, the execution parameters for the differential pressure increase step are different from those for the differential pressure equalization step. And / or, the differential pressure boosting step is further divided into multiple levels, with different condition parameters and execution parameters in each level of the differential pressure boosting step.

[0010] Furthermore, this application proposes that the pressure differential step has a total of N gears, and the current gear in the pressure differential step is the Xth gear, where X and N are positive integers, and X is less than or equal to N. When the condition parameter is lower than the high threshold of the condition parameter for the Xth gear and higher than the low threshold of the condition parameter for the Xth gear, the pressure differential step is executed according to the pre-set execution parameter value for the pressure differential step of the Xth gear. And / or, when the condition parameter is lower than the low threshold value of the condition parameter for the first gear, the equalization pressure step is executed. And / or, if the condition parameter is higher than the high value threshold of the condition parameter of the Nth gear, then the recycling step is executed.

[0011] Furthermore, this application also proposes that when N>3, the execution parameters and condition parameters have a non-linear quantization relationship.

[0012] Furthermore, this application also proposes that the execution parameters include one or more of the following: the rotational speed, power, current, and duty cycle of the bidirectional fluid-driven unit. The condition parameters include one or more of the following: a first specific liquid level condition, a first specific pressure condition, a second specific pressure condition, a third specific pressure condition, a first specific flow rate condition, and a second specific flow rate condition.

[0013] Furthermore, this application also proposes that the equalization pressure step includes forward motion and reverse motion. The pressure differential process includes forward motion and / or reverse motion. The recovery process only involves forward motion.

[0014] As can be seen from the above, the suspension side-flow filtration and sampling device and method provided in this application realize the forward and reverse flow of liquid through the bidirectional liquid driving unit and the connection structure of a specific pipeline, dynamically adjust the pressure difference to adapt to the viscosity change of the suspension, effectively avoid filter membrane clogging and maintain a stable flow rate, and have the advantages of preventing filter membrane clogging, adapting to the dynamic change of suspension viscosity, improving sample processing efficiency and system stability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a side-flow filtration and sampling method provided in this application.

[0016] Figure 2 This is a schematic diagram of a complete machine provided for this application.

[0017] Figure 3A schematic diagram of the fluid path of a bidirectional fluid driving unit provided in this application.

[0018] Figure 4 A schematic diagram illustrating the membrane flux variation trend of a side-flow filtration and sampling unit provided in this application.

[0019] Figure 5 This is a schematic diagram illustrating the pressure difference change trend provided in this application.

[0020] Figure 6 This application provides a schematic diagram of a multi-step forward and reverse motion.

[0021] In the diagram: 1. First pipeline; 2. Second pipeline; 3. Third pipeline; 4. Fourth pipeline; 5. First sample storage unit; 51. First port; 52. Second port; 6. Second sample storage unit; 61. Fifth port; 62. Sixth port; 7. Bidirectional liquid driving unit; 71. Seventh port; 72. Eighth port; 8. Side-flow filtration and sampling unit; 81. Third port; 82. Fourth port; 9. First three-way valve; 10. Second three-way valve; 11. First liquid level detection unit; 12. Second liquid level detection unit; 13. First pressure sensor (fixed on the first sample storage unit); 14. Second pressure sensor (fixed on the second sample storage unit); 15. Flow detection unit (connected to the post-membrane chamber of the side-flow filtration and sampling unit); 16. Blocking unit. Detailed Implementation

[0022] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0023] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] In traditional biomedical research and clinical diagnosis, suspensions serve as the basic samples, rich in various biological particles. However, during storage and processing, the viscosity of suspensions is easily affected by time, temperature, and biological activity factors, exhibiting a non-linear increase. This drastic viscosity change leads to problems in traditional filtration and collection technologies, such as rapid clogging of filter membrane pores, abnormally increased fluid flow resistance, significant decrease in sample throughput, and aggravated system pressure fluctuations, which can easily cause equipment failure or cross-contamination of samples.

[0025] In this regard, such as Figure 2 As shown, this embodiment provides a side-flow filtration and collection device for suspensions. This device is designed to separate and collect particles from suspensions by constructing a closed-loop fluid circulation system, aiming to achieve reciprocating flow of the suspension within the side-flow filtration and collection unit to dynamically address the challenges posed by changes in suspension viscosity. Specifically, the device includes a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a first sample storage unit, a second sample storage unit, a bidirectional liquid driving unit, and a side-flow filtration and collection unit.

[0026] For ease of understanding, the following explains some key terms in this embodiment: The side-flow filtration device for suspensions utilizes side-flow filtration technology, where the liquid flows parallel to the filter membrane surface, rather than perpendicularly through the membrane. A portion of the liquid passes through the filter membrane's pores perpendicularly, while particles that cannot pass through are trapped by the membrane and flushed away in the direction of the liquid flow. This design minimizes membrane clogging and is therefore suitable for separating and collecting particles from suspensions. The device achieves effective capture of target particles through precise fluid control and filtration mechanisms.

[0027] The first and second sample storage units are configured to temporarily store suspensions to be treated or already treated suspensions. These units typically have sufficient capacity to hold the amount of liquid required for the experiment or production and are designed to be reliably connected to the piping system.

[0028] A bidirectional fluid driving unit is used to provide driving force to make the suspension flow in a predetermined direction in the pipeline system, and can change the direction of flow as needed. This unit can generate a forward or reverse pressure difference, thereby realizing the reciprocating transport of the liquid.

[0029] The side-flow filtration unit, the core filtration component of the device, is used to separate particles from suspensions. This unit typically contains a filter medium, such as a filter membrane, which separates particles from the liquid through a physical retention mechanism. The filter membrane in the side-flow filtration unit has many tiny pores, and its internal design often contains irregular and non-smooth corners, making it prone to particle accumulation and aggregation. Therefore, using bidirectional flow to back and forth flush the filter cake layer on the membrane can more effectively reduce membrane clogging and failure. The filter membrane is preferably a hydrophilic membrane.

[0030] Specifically, the first sample storage unit is configured with a first port and a second port, the side-flow filtration and sampling unit is configured with a third port and a fourth port, the second sample storage unit is configured with a fifth port and a sixth port, and the bidirectional liquid driving unit is configured with a seventh port and an eighth port.

[0031] In terms of connections, the eighth port of the bidirectional fluid driving unit is connected to the first port of the first sample storage unit via a first conduit. The second port of the first sample storage unit is connected to the third port of the side-flow filtration unit via a second conduit. The fourth port of the side-flow filtration unit is connected to the fifth port of the second sample storage unit via a third conduit. The sixth port of the second sample storage unit is connected to the seventh port of the bidirectional fluid driving unit via a fourth conduit. This connection method forms a complete fluid loop, allowing the suspension to flow back and forth between the first sample storage unit, the side-flow filtration unit, and the second sample storage unit, with a portion of the suspension flowing away from the filter membrane, thereby achieving effective filtration of particles. For example, in one embodiment, these conduits can be flexible silicone tubing or rigid plastic tubing to adapt to different fluid transport requirements and system layouts.

[0032] Furthermore, no switching valves are installed on the second and third pipelines. This configuration aims to ensure that the flow path of the suspension between the first sample storage unit, the side-flow filtration and sampling unit, and the second sample storage unit remains unobstructed, thereby reducing resistance during fluid transmission and avoiding local pressure fluctuations or particle retention that may occur due to the presence of switching valves. In particular, as a protein solution containing a large amount of protein, after reciprocating liquid movement and passing through the switching valve located in the core pipeline section, protein aggregation is easily caused, which can lead to various abnormalities.

[0033] Furthermore, as one implementation, switching valves are provided on the first and / or fourth pipelines. These switching valves can be configured as simple plug valves or ball valves, allowing for manual control of the fluid flow path switching. In another implementation, these switching valves can be configured as solenoid valves, opening and closing via external control signals, thereby achieving remote or programmed control of fluid flow. The presence of these switching valves enables the system to manage the fluid flow path on the drive side to adapt to different operating modes. More importantly, the directional switching of bidirectional fluid-driving units (such as pumps) often involves significant changes in pressure differential, requiring a considerable amount of time to complete the entire switching process. Switching valves, however, are only related to the switching control of the fluid flow path and have a faster response time. Therefore, the introduction of switching valves greatly improves the control flexibility of the fluid circuit control system.

[0034] In addition, the core component of this application is the side-flow filtration and collection unit, which uses its filter membrane to enrich and purify microparticles (such as proteins, cells, viruses, etc.). Therefore, the first sample storage unit, the second pipeline, the side-flow filtration and collection unit, the third pipeline to the second sample storage unit are the core processing sections of the entire liquid circuit system. Valves generally include complex internal structures such as membranes and clamping mechanisms. If they are placed in this core section, it will lead to cross-contamination, local pressure fluctuations, microparticle retention or protein aggregation when processing different samples. Therefore, placing them in the first pipeline and / or the fourth pipeline increases control flexibility, avoids possible cross-contamination, and is more conducive to dealing with the problem of filter membrane pore blockage caused by nonlinear viscosity growth during the processing of suspensions.

[0035] The suspension side-flow filtration and sampling device of this embodiment constructs a closed-loop fluid circulation system comprising a first sample storage unit, a second sample storage unit, a bidirectional liquid driving unit, and a side-flow filtration and sampling unit. Utilizing specific pipeline connections and switching valve configurations, it achieves reciprocating flow of the suspension within the side-flow filtration and sampling unit. This effectively alleviates the problem of filter membrane pore blockage caused by the nonlinear increase in viscosity during suspension processing, reduces fluid flow resistance, increases sample throughput, and stabilizes system pressure fluctuations, thereby improving the efficiency and reliability of side-flow filtration and sampling.

[0036] In some of the embodiments described above in this application, a bidirectional fluid driving unit is proposed to realize the reciprocating transport of suspension. However, in practical applications, how to accurately control the driving pressure and flow direction switching of the fluid to cope with the flow resistance fluctuations caused by the drastic changes in the viscosity of the suspension and to ensure the stable operation of the system under different working conditions is still a technical problem that needs to be solved.

[0037] In this regard, such as Figure 3 As shown, this application proposes a side-flow filtration and sampling device for suspensions, wherein the bidirectional liquid driving unit includes a first three-way valve, a second three-way valve, and a bidirectional air pump. The two outlets of the bidirectional air pump are respectively connected to the normally open ports of the first and second three-way valves. The common port of the first three-way valve is connected to a first pipeline, and the common port of the second three-way valve is connected to a fourth pipeline. The normally closed ports of the first and second three-way valves are respectively connected to atmospheric pressure.

[0038] The first three-way valve is a switching valve installed on the first pipeline, and the second three-way valve is a switching valve installed on the fourth pipeline.

[0039] Specifically, a bidirectional air pump is a device capable of generating both forward and reverse airflow or pressure. Its core function is to provide driving force for the transport of suspensions and to switch the flow direction. For example, a diaphragm pump with two independent air chambers can be used to generate bidirectional airflow by alternately driving the two air chambers; or a reversible piston pump can be used to change the airflow direction by changing the direction of piston movement.

[0040] The first and second three-way valves are switching valves with three fluid channels. Their function is to switch the fluid path according to a control signal. They are generally two-position three-way valves (the most common pneumatic directional valves, mostly single-coil + spring-return solenoid valves). In this embodiment, the first and second three-way valves are used to control the airflow generated by the bidirectional air pump to enter the first or fourth pipeline and achieve connection with atmospheric pressure. For example, an electromagnetic three-way valve can be used, which controls the switching of the valve core through an electrical signal, thereby changing the fluid path; or a pneumatic three-way valve can be used, which drives the valve core to move through a pneumatic pressure signal.

[0041] The two outlets of the bidirectional air pump are connected to the normally open ports of the first three-way valve and the second three-way valve, respectively. This connection method ensures that the driving airflow generated by the bidirectional air pump can be effectively received and controlled by the first and second three-way valves, laying the foundation for subsequent flow direction switching and pressure regulation. The common port of the first three-way valve constitutes the eighth port, and the common port of the second three-way valve constitutes the seventh port.

[0042] The common port of the first three-way valve is connected to the first pipeline. This connection method allows the first three-way valve to introduce the air pressure generated by the bidirectional air pump into the first pipeline, thereby driving the suspension in the first sample storage unit to flow towards the side flow filtration and collection unit.

[0043] The common port of the second three-way valve is connected to the fourth pipeline. This connection allows the second three-way valve to introduce the air pressure generated by the bidirectional air pump into the fourth pipeline, thereby driving the suspension in the second sample storage unit to flow towards the side-flow filtration and collection unit.

[0044] The normally closed ports of the first three-way valve and the second three-way valve are connected to atmospheric pressure. Their function is to release residual pressure in the pipeline in a timely manner when not in a driven state, to avoid pressure accumulation and damage to the system, and to help the system pressure to quickly balance, so as to prepare for the next drive.

[0045] Furthermore, the frequency of the bidirectional air pump is lower than the switching frequency of the first three-way valve and / or the second three-way valve. This frequency relationship ensures that when switching flow directions, the action of the three-way valve can precede or at least synchronize with the pressure build-up or reversal of the bidirectional air pump. For example, the switching valve can quickly switch to position before the air pump starts working or after it stops working, or complete the switching before the air pump reverses its drive. This helps avoid fluid shocks at the moment of switching, reduces pressure fluctuations, thereby protecting system components and improving the smoothness and reliability of flow direction switching.

[0046] Furthermore, within one cycle of forward / reverse switching of the bidirectional air pump, both the first and second three-way valves complete at least one reversing action. This frequency relationship ensures that during flow direction switching, the action of the three-way valves precedes or at least synchronizes with the pressure build-up or reversal of the bidirectional air pump. For example, the switching valves can quickly switch to position before the air pump starts operating or after it stops operating, or complete the switching before the air pump reverses its drive. This helps avoid fluid shocks at the moment of switching, reduces pressure fluctuations, thereby protecting system components and improving the smoothness and reliability of flow direction switching.

[0047] By introducing a drive system consisting of a bidirectional air pump, a first three-way valve, and a second three-way valve, this application achieves precise control over the flow direction and driving pressure of the suspension. The bidirectional air pump provides forward and reverse driving forces, while the first and second three-way valves direct the driving force of the air pump to the first or fourth pipeline, thereby realizing the reciprocating transport of the suspension between the first and second sample storage units. The normally closed port of the three-way valve, connected to atmospheric pressure, provides an effective pressure relief and balancing mechanism for the system, enabling timely elimination of residual pressure in the pipeline, preventing blockage or damage caused by pressure accumulation, and ensuring rapid pressure stabilization between different driving cycles. Furthermore, by controlling the frequency of the bidirectional air pump to be lower than the frequency of the switching valve, it is ensured that during flow direction switching, the action of the switching valve can precede or be synchronized with the pressure establishment or reversal of the air pump, thereby effectively avoiding fluid impact and pressure oscillation, and significantly improving the smoothness and reliability of flow direction switching. This drive architecture not only enhances the device's ability to transport high-viscosity suspensions, but also improves the system's adaptability and stability in complex filtration environments through the flexibility of pneumatic control. It effectively solves the problem of flow resistance fluctuations caused by drastic changes in suspension viscosity, ensuring the stable operation of the device under various working conditions.

[0048] In some of the embodiments described above in this application, a basic pipeline connection and liquid driving structure for a suspension side-flow filtration and collection device are proposed to achieve the filtration and collection of particles. However, in the process of its implementation, due to the lack of a real-time monitoring and feedback mechanism for the internal state of the system, the system cannot sense the actual position of the suspension in the pipeline, pressure changes, and the real-time flow rate of the fluid passing through the filter membrane. As a result, when faced with complex working conditions such as drastic viscosity changes or filter membrane blockage, the system is difficult to perform precise pressure regulation and operation control, which can easily lead to problems such as filter membrane overload or low sample processing efficiency.

[0049] In this regard, this application further proposes that the side-flow filtration and sampling device also includes a first liquid level detection unit and a second liquid level detection unit.

[0050] The first and second liquid level detection units are devices used to monitor the liquid level in specific containers or pipelines in real time. Their function is to provide accurate information on the liquid level status so that the system can perform corresponding control operations. Specifically, a photoelectric liquid level sensor can be used, which determines the liquid level position by detecting changes in the refraction or reflection of a light beam in the liquid. When the liquid level reaches the sensor position, the light path is blocked or reflected by the liquid, thereby triggering a signal. Alternatively, a capacitive liquid level sensor can be used, which senses the liquid level by detecting changes in the dielectric constant of the liquid. When the liquid touches or moves away from the sensor, the capacitance value changes, thus indicating the liquid level. These liquid level detection units can capture the dynamic position of the suspension in the pipeline in real time, providing accurate triggering basis for subsequent liquid driving direction switching and stroke control, ensuring the accuracy of the reciprocating movement of the liquid between the sample storage unit and the filtration unit.

[0051] In this regard, this application further proposes that the side-flow filtration and sampling device also includes a first pressure sensor.

[0052] The first pressure sensor is a device that senses pressure and converts it into an electrical signal. Its function is to monitor the fluid pressure inside the system in real time to reflect the fluid flow state and system resistance. For example, a piezoresistive pressure sensor can be used, which determines the pressure by measuring the change in resistance under pressure. Alternatively, a capacitive pressure sensor can be used, which determines the pressure by measuring the change in capacitance under pressure. This sensor can monitor the pressure status inside the first sample storage unit or during the side-flow filtration process in real time, identifying pressure anomalies caused by viscosity changes or filter membrane blockage.

[0053] In this regard, this application further proposes that the side-flow filtration and sampling device also includes a second pressure sensor.

[0054] The second pressure sensor, similar to the first, is also used to sense and convert pressure signals. It is typically used in conjunction with the first pressure sensor to monitor different locations or pressure differences. It can also be implemented using a piezoresistive or capacitive pressure sensor. When used in conjunction with the first pressure sensor, it can provide more comprehensive pressure distribution information, such as monitoring the pressure difference across the side-flow filtration unit, thereby more accurately assessing the degree of filter membrane clogging or fluid resistance.

[0055] In this regard, this application further proposes that the side-flow filtration and sampling device also includes a flow detection unit.

[0056] A flow detection unit is a device used to measure the volume or mass of fluid passing through a cross-section per unit time. Its function is to quantify the fluid flow rate to evaluate filtration efficiency or system performance. Specifically, a differential pressure flow meter can be used, calculating the flow rate by measuring the pressure difference before and after the fluid passes through a throttling device. Alternatively, an ultrasonic flow meter can be used, calculating the flow rate by measuring the time difference of ultrasonic wave propagation in the forward and reverse directions. This unit can directly acquire the liquid flow rate information passing through the side-flow filtration unit, quantitatively evaluate the filtration performance and permeability of the filter membrane, and thus respond promptly when filtration efficiency decreases.

[0057] Through the above technical solution, this application introduces a first liquid level detection unit, a second liquid level detection unit, a first pressure sensor, a second pressure sensor, and a flow detection unit into the suspension side-flow filtration and collection device, thereby transforming the originally open-loop liquid driving process into a closed-loop intelligent control process. Specifically, the first and second liquid level detection units can monitor the liquid level status of the suspension in real time during its reciprocating motion between the first and second sample storage units and the side-flow filtration and collection unit, providing key liquid level trigger signals for the precise control of the bidirectional liquid driving unit and ensuring the accurate position and stroke of the liquid in the pipeline. Simultaneously, the first and / or second pressure sensors can sense pressure changes within the system in real time, such as the pressure within the first or second sample storage unit and the pressure difference across the side-flow filtration and collection unit, thereby promptly detecting abnormal pressure increases caused by drastic changes in suspension viscosity or filter membrane blockage. Furthermore, the flow detection unit can directly measure the liquid flow rate through the side-flow filtration and collection unit, quantitatively evaluating the permeability and filtration efficiency of the filter membrane. The synergistic effect of these sensing units enables the device to comprehensively and in real-time acquire multi-dimensional operating parameters of the suspension, such as liquid level, pressure, and flow rate. Based on this real-time data, the system can intelligently adjust the operating parameters of the bidirectional fluid driving unit to cope with different operating conditions. For example, when an abnormal increase in pressure or a significant decrease in flow rate is detected, the system can automatically adjust the fluid driving strategy to avoid overloading or clogging of the filter membrane and optimize filtration efficiency. This real-time monitoring and feedback mechanism effectively solves the "blind control" problem caused by the lack of internal state perception in existing technologies, significantly improving the robustness, reliability, and processing efficiency of the device when handling high-viscosity or easily clogged suspensions, and ensuring the stability and accuracy of the particle collection process.

[0058] In some of the embodiments described above in this application, a liquid level detection unit, a pressure sensor, and a flow detection unit are proposed to assist the side-flow filtration process. However, in practical applications, it is difficult to accurately perceive the drastic changes in the viscosity of the suspension and the clogging status of the filter membrane by relying solely on the basic detection unit. This results in the system being unable to dynamically adjust the filtration strategy according to the real-time operating conditions, which in turn leads to premature failure of the filter membrane or low sample processing efficiency.

[0059] In this regard, this application further proposes that the first liquid level detection unit is installed on the second pipeline, and the second liquid level detection unit is installed on the third pipeline.

[0060] Specifically, the liquid level detection unit is used to monitor the position or flow status of the liquid in the pipeline in real time. For example, an optical liquid level sensor, such as an infrared through-beam sensor, can be used. When the liquid flows past the sensor position, the light path is blocked, thereby triggering a signal. Alternatively, a capacitive liquid level sensor can be used, which determines the liquid level position by detecting changes in capacitance when liquid is present. An ultrasonic liquid level sensor can also be used, which determines the liquid level position by utilizing the reflection characteristics of ultrasonic waves. By placing the first liquid level detection unit on the second pipeline and the second liquid level detection unit on the third pipeline, the flow of the suspension between the first sample storage unit and the side-flow filtration unit, as well as between the side-flow filtration unit and the second sample storage unit, can be sensed in real time, providing crucial timing information for subsequent filtration process control.

[0061] In this regard, this application further proposes that the first pressure sensor is directly connected to the first sample storage unit; and / or, the second pressure sensor is directly connected to the second sample storage unit.

[0062] Pressure sensors are used to accurately measure fluid pressure. For example, piezoresistive pressure sensors or MEMS (microelectromechanical systems) pressure sensors can be used, which are characterized by high accuracy and fast response; alternatively, capacitive pressure sensors or strain gauge pressure sensors can be employed. By directly connecting the first pressure sensor to the first sample storage unit and the second pressure sensor directly to the second sample storage unit, the interference of pipeline resistance on the pressure measurement results can be minimized, thereby obtaining more accurate pressure data within the sample storage units. This direct connection method ensures accurate monitoring of the pressure difference across the filter collection unit, which is an important basis for assessing the degree of filter membrane clogging and changes in suspension viscosity.

[0063] In this regard, this application further proposes that the side-flow filtration and sampling unit also includes an inner cavity and a hydrophilic membrane, the hydrophilic membrane dividing the inner cavity into a pre-membrane cavity and a post-membrane cavity, and the flow detection unit is used to detect the flow rate flowing out of the post-membrane cavity.

[0064] The inner cavity of the side-flow filtration unit is the space used to contain the suspension and perform the filtration operation. The hydrophilic membrane is the core component for particle separation; its material can be polyethersulfone (PES), polyvinylidene fluoride (PVDF), or nylon, with the appropriate pore size selected based on the size of the target particles; hydrophilic materials such as cellulose acetate or polycarbonate can also be used. The hydrophilic membrane divides the inner cavity into a pre-membrane chamber and a post-membrane chamber. The pre-membrane chamber receives the suspension to be filtered, while the post-membrane chamber collects the filtered liquid. The flow detection unit is used to measure the flow rate of the filtrate exiting the post-membrane chamber in real time. For example, a microfluidic thermal flow sensor or an ultrasonic flow sensor can be used, which can non-invasively and accurately measure minute flow rates; alternatively, a Coriolis flow sensor can be used, or the flow rate can be indirectly measured by timing through a metering chamber of known volume at the outlet of the post-membrane chamber. By monitoring the flow rate in the post-membrane chamber, the permeability and efficiency of the filter membrane can be directly reflected.

[0065] Through the above technical solutions, this application constructs a multi-dimensional, high-precision sensing system for the filtration and collection process. The first and second liquid level detection units can monitor the flow state and position of the liquid in the pipeline in real time, promptly detecting abnormal flow or stagnation, providing fundamental data for determining whether the filtration and collection process is smooth. The first and second pressure sensors are directly connected to the sample storage unit, accurately acquiring the real-time pressure difference across the filtration and collection unit, effectively avoiding interference from pipeline resistance on the measurement results, thereby accurately assessing the degree of membrane clogging and changes in suspension viscosity. Furthermore, the hydrophilic membrane structure inside the side-flow filtration and collection unit, combined with the flow detection unit's monitoring of the flow rate in the post-membrane chamber, can directly quantify the membrane's permeation rate, providing early warning in the initial stages of membrane performance degradation. These multi-source sensor data complement and corroborate each other, providing comprehensive and real-time operating information for the system. This enables the system to accurately sense drastic changes in suspension viscosity and membrane clogging status, thereby dynamically adjusting the filtration and collection strategy, effectively preventing premature membrane failure, and significantly improving sample processing efficiency and filtration and collection stability.

[0066] In some of the solutions described above in this application, a device for filtration of suspension is proposed by connecting the sample storage unit and the side flow filtration unit through a pipeline. However, in the process of its implementation, as the viscosity of the suspension increases nonlinearly, a single filtration mode is difficult to cope with the problems of filter membrane clogging and increased fluid resistance, resulting in large system pressure fluctuations and low filtration efficiency, and lacking a dynamic pressure regulation mechanism for different filtration stages.

[0067] In this regard, such as Figure 1 As shown, this application proposes a side-flow filtration method, which includes a differential pressure equalization step and a differential pressure increase step.

[0068] The pressure equalization step aims to maintain a relatively stable and controlled pressure difference across the two ends of the side-flow filtration unit. This step ensures that the suspension passes smoothly through the filter membrane during the initial filtration phase, effectively preventing premature particle accumulation and membrane clogging caused by sudden pressure changes. In practice, this can be achieved in various ways. For example, the bidirectional flow unit can operate at a constant speed, power, or duty cycle to generate a stable pressure difference, ensuring predictable flow rates and minimizing pressure fluctuations. In practice, as the pressure equalization step progresses, the suspension viscosity begins to increase slowly. However, when the increase is small, the operating parameters of the pressure equalization step (except for the direction of suspension movement) should be kept as unchanged as possible, maintaining the pressure difference within a preset narrow range to accommodate minor changes in suspension viscosity or flow resistance.

[0069] Furthermore, the operating parameters of the bidirectional fluid displacement unit are kept at preset constant values. As the pressure equalization step proceeds, the viscosity of the suspension begins to increase slowly, but when the increase is small, the operating parameters of the pressure equalization (except for the direction of suspension movement) are kept as unchanged as possible, so that the pressure difference is maintained within a preset narrow range to accommodate small changes in the viscosity or flow resistance of the suspension.

[0070] In this regard, such as Figure 1 As shown, this application proposes a side-flow filtration method, which further includes a recovery step.

[0071] The pressure differential boosting step, building upon the pressure differential equalization step, actively increases the pressure difference across the two ends of the side-flow filtration unit. The core purpose of this step is to overcome the increased flow resistance caused by rising suspension viscosity and particle accumulation on the filter membrane as the filtration process progresses. By strategically increasing the pressure differential, an effective sample throughput rate can be maintained even in the later stages of filtration, thereby mitigating the negative impact of filter membrane pore blockage. In practice, a gradual pressure boosting approach can be adopted, where the operating parameters of the bidirectional liquid driving unit (e.g., rotational speed, power, current, or duty cycle) can be gradually increased over time or in multiple preset stages to achieve controlled pressure differential growth. Alternatively, based on real-time monitored condition parameters (e.g., flow rate detected by the flow detection unit or pressure sensor readings), when these parameters reach preset thresholds, an increase in the output of the bidirectional liquid driving unit can be triggered to further increase the pressure differential.

[0072] like Figure 4 As shown, in the early stages of suspension treatment, the concentration and viscosity of the suspension are low, and the flow is smooth. The side-flow filtration unit with a filter membrane actually uses side-flow filtration technology, utilizing the relatively fast flow rate of the liquid to carry away most of the deposits on the filter membrane. However, as the treatment process progresses, some particles will still deposit on the filter membrane, gradually clogging some of the filter pores, causing the membrane flux to continuously decrease until the filter membrane eventually fails. Therefore, if not properly treated, the trend of membrane flux change will be as follows. Figure 4As shown by the dashed line, after introducing the pressure differential step, the membrane flux failure trend is significantly alleviated, and a high membrane flux can be maintained for a longer period of time, even slightly higher than the membrane flux before the introduction of the pressure differential step. The trend is as follows: Figure 4 The solid line indicates the portion shown.

[0073] The recovery step is designed to maintain the system, recover residual samples, or prepare for subsequent operations. This step aims to prevent sample loss, reduce the risk of cross-contamination, and maintain the cleanliness and functionality of the sideflow filtration unit. In practice, the recovery step may consist solely of forward motion. For example, a bidirectional liquid-driven unit can first use a blocking unit to locally prepare a sufficient quantity and pressure of gas in the piping, then suddenly release this high-pressure gas. The sufficient positive pressure forces the residual liquid to move forward at a specific rate, pushing the residual liquid in the sideflow filtration unit and related piping into a second sample storage unit or a dedicated collection container to maximize sample recovery. Alternatively, after filtration, a cleaning fluid or air can be driven through the entire system via forward motion to clear all fluid paths and the sideflow filtration unit, preparing it for the next sample processing or system storage. Here, the blocking unit can be a shut-off valve, but not a switching valve similar to a two-position three-way valve.

[0074] Through the above technical solutions, the side-flow filtration method proposed in this application can effectively solve the problems of filter membrane clogging, increased fluid resistance, large system pressure fluctuations, and low filtration efficiency caused by the nonlinear increase in viscosity during the filtration process of suspensions. The pressure equalization step ensures the stability and efficiency of the initial filtration stage, avoiding premature filter membrane clogging. The pressure increase step effectively overcomes the challenges caused by increased viscosity and filter membrane clogging in the later stages by dynamically adjusting the pressure, ensuring continuous filtration performance and sample throughput. The recovery step further improves the reliability of the system and the integrity of the sample. Combining the first liquid level detection unit, the second liquid level detection unit, the first pressure sensor, the second pressure sensor, and the flow detection unit set in the above-mentioned side-flow filtration device, this method can intelligently switch and adjust parameters between the pressure equalization step, the pressure increase step, and the recovery step based on real-time monitoring data, thereby realizing refined management and dynamic control of the filtration process, significantly improving the efficiency and stability of suspension side-flow filtration, and effectively extending the service life of the filter membrane.

[0075] In some of the solutions described above in this application, pressure equalization step, pressure increase step, and recovery step are proposed to achieve side-flow filtration of suspension. However, in the actual filtration process, since the viscosity of the suspension increases non-linearly over time, if the motion mode in the filtration process is too simple or lacks specificity, it will cause the filter membrane pores to be blocked quickly and cannot effectively cope with the changes in fluid flow resistance at different viscosity stages, thereby causing the sample throughput rate to decrease and the system pressure to fluctuate.

[0076] In this regard, such as Figure 6 As shown, this application further proposes a side-flow filtration and sampling method, wherein the differential pressure equalization step includes forward motion and reverse motion.

[0077] This pressure equalization step aims to balance the pressure on both sides of the side-flow filtration unit through bidirectional flow, thereby effectively reducing particle accumulation on the filter membrane surface and maintaining membrane permeability. The combination of forward and reverse motion creates a reciprocating scouring effect on the filter membrane. In other words, the pressure equalization step must include at least one forward motion and at least one reverse motion. Specifically, this can be achieved by controlling a bidirectional liquid driving unit (e.g., a bidirectional air pump) to alternately drive the liquid to flow back and forth between the first and second sample storage units. A relatively low driving pressure is maintained each time the flow direction changes to achieve pressure equalization on both sides of the filter membrane. Alternatively, a fixed number of cycles or duration can be set; for example, performing a forward motion for a preset duration followed by a reverse motion for a preset duration, repeating this cycle multiple times, with consistent flow rate or pressure parameters for each motion to ensure sufficient reciprocating scouring of the filter membrane.

[0078] In this regard, such as Figure 6 As shown, this application further proposes a side-flow filtration method, wherein the pressure differential step includes forward motion and / or reverse motion.

[0079] like Figure 5 As shown, this differential pressure boosting step aims to flexibly adjust the fluid drive direction and intensity based on the actual flow resistance changes caused by the increase in suspension viscosity or filter membrane clogging during the filtration process, ensuring that particles can still be effectively collected under different pressure requirements. Specifically, the system can intelligently determine the current degree of filter membrane clogging or the viscosity change of the suspension based on data from real-time monitored pressure sensors (such as the first pressure sensor and the second pressure sensor) or flow detection unit. If a greater driving force is needed to overcome the resistance, forward or reverse motion is selected, and the driving force of the bidirectional fluid driving unit is gradually increased (e.g., increasing the power, speed, or duty cycle of the bidirectional air pump). Alternatively, multiple differential pressure boosting levels can be preset, each corresponding to a different driving direction and driving intensity. For example, at one level, only forward motion is performed, and the driving force is higher than that of the differential pressure equalization step; at another level, only reverse motion is performed, and the driving force is also higher than that of the differential pressure equalization step; or in some cases, forward and reverse motion are alternated, but the driving force of each motion is higher than that of the differential pressure equalization step, to adapt to different filtration requirements. In other words, the pressure differential step includes at least one forward motion or at least one reverse motion, but may also include at least one (or even multiple) forward motions and at least one (or even multiple) reverse motions.

[0080] In this regard, such as Figure 6As shown, this application further proposes a side-flow filtration and sampling method, wherein the recovery step only includes forward motion.

[0081] This recovery step aims to first close the pipeline via a shut-off unit when the filtration task is completed or the pipeline needs cleaning. Sufficient quantity and pressure of gas are then locally prepared within the pipeline, and this high-pressure gas is suddenly released. Through unidirectional forced actuation, residual samples or particles are efficiently removed from the system, preventing cross-contamination or precipitation caused by sample retention in the pipeline. The shut-off unit is a fluid control device whose main function is to control the opening and closing of the second pipeline as needed. When not powered, the shut-off unit remains open, allowing free liquid flow; when powered on, its internal mechanism activates, closing the second pipeline and blocking liquid flow. This design allows the system to flexibly isolate or pressure specific pipelines. More importantly, in the subsequent recovery steps, the blocking unit first blocks the liquid flow and then delivers gas to the first sample storage unit through the bidirectional liquid driving unit, bringing the gas pressure in the first sample storage unit to its maximum possible value. Then, the blocking unit is quickly opened, allowing gas to flow through the pipeline, impacting the residual material in the side-flow filtration unit at the highest pressure (which also means the greatest shear force), thus recovering it to the second sample storage unit. Specifically, in the recovery step, the bidirectional liquid driving unit continuously drives the liquid at high intensity in a preset direction (e.g., from the first sample storage unit to the side-flow filtration unit, and then to the second sample storage unit), ensuring that the liquid in the first, second, side-flow filtration units, third, and fourth pipelines is completely discharged or collected in the second sample storage unit. Alternatively, by precisely controlling the opening and closing of the switching valves on the first and / or fourth pipelines, in conjunction with the unidirectional drive of the bidirectional liquid driving unit, the liquid is forced to flow along a preset forward path, pushing all residues towards the second sample storage unit or the waste liquid collection end, thereby achieving thorough system cleaning. More importantly, during the recovery step, the liquid level in the first sample storage unit continuously decreases as the pressure equalization step proceeds, thus enabling it to hold a large amount of positive pressure gas (essentially equivalent to a relatively large gas tank). Furthermore, during the opening process in the recovery step, it provides prolonged and high-pressure gas impact and shear forces, thereby efficiently recovering the gel-like material and gas-liquid mixture from the side-flow filtration unit to the second sample storage unit. In other words, the recovery step consists of only one forward motion.

[0082] Through the above technical solution, this application can effectively address the challenges posed by the nonlinear viscosity increase of suspensions during filtration. In the initial stage of filtration, the differential pressure equalization step, through alternating forward and reverse motion, achieves reciprocating scouring of the filter membrane in the side-flow filtration unit, effectively preventing premature accumulation and clogging of particles on the membrane surface, thereby maintaining membrane permeability and extending filtration life. As filtration progresses, when the suspension viscosity increases or the membrane resistance increases, the differential pressure increase step can selectively execute forward and / or reverse motion according to the actual situation, and the driving intensity can be adjusted to flexibly cope with constantly changing flow resistance, ensuring that particles can still be efficiently and stably collected under different pressure requirements. Furthermore, when the filtration task is completed or system cleaning is required, the recovery step uses only forward motion. Through forced pressure buildup and then unidirectional forced drive, residual samples or particles in the pipeline and side-flow filtration unit can be efficiently discharged, avoiding cross-contamination and sedimentation caused by sample retention, ensuring the accuracy of filtration results and the cleanliness of the system. Overall, this phased, dynamically adjusted motion mode strategy significantly improves the efficiency, reliability, and adaptability of suspension side-flow filtration and effectively solves the technical problems of easy clogging of the filter membrane and low sample processing efficiency under a single motion mode.

[0083] In some embodiments of this application, a bidirectional liquid driving unit is proposed to drive the suspension to flow back and forth between the sample storage unit and the side-flow filtration unit to achieve filtration. However, during the flow in one direction, due to the nonlinear increase of the suspension viscosity over time, the particles are very easy to accumulate rapidly on the filter membrane surface to form a filter cake layer, which leads to the blockage of the filter membrane pores, causing the fluid flow resistance to increase sharply, the sample throughput rate to decrease significantly, and it is difficult to achieve effective self-cleaning of the filter membrane surface and uniform distribution of particles through simple unidirectional flow.

[0084] In this regard, this application further proposes that during forward motion, liquid flows from the first sample storage unit to the side-flow filtration and sampling unit, a portion of the liquid flows away through the membrane of the side-flow filtration and sampling unit, and the remaining liquid flows through the side-flow filtration and sampling unit and then to the second sample storage unit.

[0085] The forward motion refers to the flow process in which liquid, driven by the bidirectional driving unit, flows from the first sample storage unit through the side-flow filtration unit and finally to the second sample storage unit. This motion aims to achieve preliminary filtration of the suspension and retention of particles, while reducing particle accumulation on the filter membrane surface through tangential flow. This motion can be achieved by generating a positive pressure difference through the bidirectional driving unit to push the suspension in the first sample storage unit towards the side-flow filtration unit, or by generating negative pressure on the second sample storage unit side for suction.

[0086] The liquid flows from the first sample storage unit to the side-flow filtration unit, its function being to introduce the suspension to be treated into the side-flow filtration unit for filtration. This is typically achieved by controlling the operating direction and intensity of the bidirectional liquid driving unit to establish a pressure gradient from the first sample storage unit to the side-flow filtration unit, for example, by applying positive pressure to the first sample storage unit via an air pump, or by generating negative pressure downstream of the side-flow filtration unit.

[0087] A portion of the liquid flows away through the membrane of the side-flow filtration unit, which serves to separate the particles in the suspension from the liquid, i.e., the filtration process. The side-flow filtration unit contains a filter membrane with a specific pore size. Under pressure difference, the liquid permeates through the membrane, while the particles are retained. The liquid that flows away is the filtrate or permeate. This filter membrane can be a microporous membrane, an ultrafiltration membrane, etc., and its material can be polyethersulfone, polyvinylidene fluoride, etc.

[0088] The remaining liquid flows through the side-flow filtration unit and then to the second sample storage unit. This liquid typically refers to the concentrate or retentate that did not pass through the filter membrane. Its flow to the second sample storage unit helps maintain tangential flow on the membrane surface, reduces particle accumulation on the membrane surface, and provides a liquid source for subsequent reverse flow. The side-flow filtration unit can be designed in a tangential flow filtration mode, allowing some liquid to flow along the membrane surface, carrying away the retentate particles and into the second sample storage unit; alternatively, through pipeline design and pressure control, it can be ensured that the unfiltered liquid can smoothly exit from the side-flow filtration unit and be collected in the second sample storage unit.

[0089] In this regard, this application further proposes that in the reverse motion, the liquid flows from the second sample storage unit to the side-flow filtration and sampling unit, a portion of the liquid flows away through the membrane of the side-flow filtration and sampling unit, and the remaining liquid flows through the side-flow filtration and sampling unit and flows to the first sample storage unit.

[0090] Reverse motion refers to the flow process in which liquid, driven by the bidirectional liquid driving unit, flows from the second sample storage unit through the side-flow filtration unit and finally back to the first sample storage unit. This back-and-forth (or reciprocating) motion is mainly used for the self-cleaning of the filter membrane. Through forward and reverse flushing, it removes particles accumulated on the surface of the filter membrane, restores the membrane's permeability, and can return some liquid to the first sample storage unit. This motion can be achieved by generating a reverse pressure difference through the bidirectional liquid driving unit to push the liquid in the second sample storage unit towards the side-flow filtration unit, or by creating negative pressure on the first sample storage unit side for suction.

[0091] Liquid flows from the second sample storage unit to the side-flow filtration unit, its function being to introduce the liquid from the second sample storage unit into the side-flow filtration unit for backwashing or further treatment. This is typically achieved by controlling the operating direction and intensity of the bidirectional liquid driving unit to establish a pressure gradient from the second sample storage unit to the side-flow filtration unit, for example, by applying positive pressure to the second sample storage unit via an air pump, or by generating negative pressure downstream of the side-flow filtration unit (near the first sample storage unit).

[0092] A portion of the liquid flows away through the membrane of the side-flow filtration unit, while the remaining liquid flows through the side-flow filtration unit and towards the first sample storage unit. This remaining liquid, typically containing particles flushed off by backflow, returns to the first sample storage unit, enabling further enrichment and concentration of the sample. In reverse flow mode, the side-flow filtration unit allows some liquid to flow along the membrane surface, carrying away the flushed particles and into the first sample storage unit; alternatively, through pipeline design and pressure control, it ensures that liquid that has not passed through the filtration membrane can smoothly exit the side-flow filtration unit and be collected in the first sample storage unit.

[0093] By alternating forward and reverse motions, this application constructs a bidirectional circulating flow mechanism that effectively solves the problems of membrane clogging and flow rate attenuation caused by the nonlinear increase in suspension viscosity. In the forward motion, liquid flows from the first sample storage unit to the side-flow filtration unit, achieving preliminary filtration. Simultaneously, the remaining liquid flows to the second sample storage unit, forming a tangential flow that effectively inhibits excessive particle accumulation on the membrane surface. Subsequently, through reverse motion, liquid flows from the second sample storage unit back to the side-flow filtration unit, physically flushing the membrane surface, removing accumulated particles, and restoring membrane permeability. This alternating forward and reverse flow not only dynamically adjusts the particle distribution on the membrane surface, preventing rapid cake formation, but also effectively addresses flow resistance fluctuations caused by changes in suspension viscosity, ensuring the continuity and stability of the side-flow filtration process, significantly extending membrane lifespan, and improving particle filtration efficiency.

[0094] In some of the embodiments described above in this application, pressure equalization and pressure increase steps are proposed to achieve side-flow filtration of suspensions. However, in practical applications, since the viscosity of the suspension increases nonlinearly over time and the particle aggregation and sedimentation behavior is complex and variable, if the execution parameters in the filtration process remain fixed, the system will be unable to adapt to the dynamic evolution of the physical properties of the sample, which will lead to problems such as filter membrane blockage, abnormal increase in fluid resistance, or low filtration efficiency.

[0095] In response, this application further proposes a side-flow filtration and sampling method, wherein the execution parameters remain unchanged during the differential pressure equalization step.

[0096] Specifically, execution parameters refer to the control quantities used to drive the flow of the suspension during side-flow filtration, such as the rotational speed, power, current, or duty cycle of the bidirectional flow-driven unit. During the pressure equalization step, these execution parameters are kept constant to provide the system with a stable initial or baseline operating state. This can be achieved by pre-setting a constant driving force output, for example, by setting the bidirectional flow-driven unit to operate at a fixed speed or power; or by maintaining a constant pressure difference through the control system, for example, by adjusting the output of the bidirectional flow-driven unit to keep the pressure difference across the membrane at a preset value. These constant execution parameters help establish stable hydrodynamic conditions in the early stages of filtration or when the suspension viscosity is low, ensuring basic filtration efficiency.

[0097] In response, this application further proposes a side-flow filtration method, wherein the execution parameters during the pressure differential step are different from those during the pressure equalization step, depending on the different condition parameters.

[0098] Conditional parameters refer to real-time monitoring data reflecting the state of the suspension or the operating status of the system during the side-flow filtration process, such as liquid level conditions, pressure conditions, or flow rate conditions. When the system enters the differential pressure boosting step, in order to cope with changes in suspension viscosity or filter membrane clogging, it is necessary to dynamically adjust the execution parameters based on changes in these conditional parameters. For example, when an increase in fluid resistance is detected (change in conditional parameters), the system can correspondingly increase the rotation speed or power of the bidirectional fluid driving unit (adjustment of execution parameters) to maintain or increase the filtration rate. This adjustment can be achieved through preset control strategies, such as PID regulation based on feedback control, or by consulting a preset parameter mapping table, thereby enabling the system to adapt to dynamic changes in suspension characteristics.

[0099] In response, this application further proposes a side-flow filtration method, wherein the differential pressure step is divided into multiple levels, and the condition parameters and execution parameters are different in each level of the differential pressure step.

[0100] Furthermore, subdividing the differential pressure step into multiple levels means that the system can switch between different driving intensities and filtration modes based on the actual state of the suspension. Each level corresponds to a specific range of condition parameters and corresponding execution parameter settings. For example, when condition parameters (such as differential pressure or flow rate) are at a low level, the system may operate at a lower level with relatively mild execution parameters; while when condition parameters indicate severe membrane clogging or extremely high viscosity, the system can switch to a higher level with stronger driving force. This leveled design can be implemented through preset threshold logic, meaning that when a condition parameter reaches a certain threshold, the system automatically switches to the next level and loads the corresponding execution parameters. This refined, hierarchical control allows the system to respond more flexibly and accurately to various complex operating conditions that may occur during the filtration process.

[0101] Through the above technical solution, this application maintains constant execution parameters during the differential pressure equalization step, providing a stable baseline operating state for the filtration process and ensuring basic filtration efficiency in the initial stage or under low viscosity conditions. Building upon this, for the differential pressure boosting step, this application introduces a mechanism for dynamically adjusting execution parameters based on conditional parameters, enabling the device to respond in real-time to dynamic changes such as suspension viscosity, particle aggregation degree, and filter membrane clogging status. Specifically, by subdividing the differential pressure boosting step into multiple levels and setting different conditional parameter ranges and corresponding execution parameters for each level, this application constructs a graded response intelligent control strategy. This strategy allows the system to accurately match the optimal driving force output based on real-time monitored conditional parameters such as liquid level, pressure, or flow rate, for example, adjusting the rotation speed, power, current, or duty cycle of the bidirectional liquid driving unit. Compared to fixed-parameter filtration methods, this scheme significantly improves the adaptability and operational stability of the side-flow filtration device to suspensions of different concentrations and viscosities. It effectively avoids problems such as rapid membrane clogging, abnormal increase in fluid resistance, and low filtration efficiency caused by a sharp increase in viscosity, thereby ensuring the continuity, efficiency, and reliability of the side-flow filtration process.

[0102] In some of the embodiments described above in this application, side-flow filtration is proposed through a pressure equalization step and a pressure increase step. However, in actual operation, since the viscosity of the suspension increases non-linearly over time, a single drive control parameter is difficult to adapt to the changes in fluid resistance at different stages, which leads to premature clogging of the filter membrane or low filtration efficiency. There is a lack of fine adjustment methods for different working conditions.

[0103] In this regard, this application further proposes that the execution parameters include one or more of the following: rotational speed, power, current, and duty cycle of the bidirectional fluid driving unit.

[0104] Specifically, the execution parameters are used to directly control the operating state of the bidirectional fluid-driving unit, thereby adjusting the driving force on the suspension. The rotational speed of the bidirectional fluid-driving unit refers to the rotational speed or reciprocating frequency of the unit (e.g., a bidirectional air pump). This can be achieved by adjusting the input voltage, current, or pulse signal frequency of the drive motor. For example, for a stepper motor, the rotation angle and speed can be precisely controlled by controlling the number and frequency of pulses; for a DC motor, the speed can be controlled by adjusting the supply voltage or the pulse width modulation (PWM) duty cycle. Power refers to the rate at which the bidirectional fluid-driving unit consumes or outputs energy during operation. This can be achieved by monitoring or controlling the input power of the drive motor. For example, the system can be kept stable by adjusting the power supply output power or limiting the maximum power output of the motor. Current refers to the magnitude of the current flowing through the drive motor of the bidirectional fluid-driving unit. This can be monitored in real time by a current sensor and controlled according to a preset current threshold. For example, the torque or thrust of the motor can be controlled by adjusting the output current of the drive circuit. Duty cycle refers to the ratio of the duration of the high level within one cycle to the total cycle in pulse width modulation (PWM) control. By adjusting the duty cycle, the average output power or average driving force of the bidirectional liquid driving unit can be effectively controlled. For example, for an air pump, its average air pressure output can be controlled by adjusting the duty cycle of its drive signal.

[0105] In this regard, this application further proposes that the condition parameters include one or more of the following: a first specific liquid level condition, a first specific pressure condition, a second specific pressure condition, a third specific pressure condition, a first specific flow rate condition, and a second specific flow rate condition.

[0106] Conditional parameters are used to reflect the physical state during the sideflow filtration and sampling process in real time, serving as the basis for adjusting execution parameters.

[0107] The first specific liquid level condition refers to a specific condition related to the state of the liquid level. This could be the liquid level position, the rate of change of the liquid level, or the time relationship between specific liquid levels detected by the first liquid level detection unit and / or the second liquid level detection unit. For example, it could be triggered when the liquid level reaches a certain preset height, or when the liquid level fails to reach the preset height within a specific time.

[0108] The first specific pressure condition refers to a specific condition related to the internal pressure of the system. This could be the absolute pressure value, pressure change rate, or pressure fluctuation amplitude detected by the first or second pressure sensor. For example, it might be triggered when the pressure exceeds a safety threshold or when there is abnormal pressure fluctuation. The second specific pressure condition refers to another set of specific conditions related to the internal pressure of the system. This could refer to the pressure difference between the first and second pressure sensors, the maximum pressure difference, or the trend of pressure difference changes. For example, it might be triggered when the pressure difference across the filter membrane reaches a certain critical value. The third specific pressure condition refers to yet another set of specific conditions related to the internal pressure of the system. This could refer to the specific pressure range or pressure change pattern required by the system in a specific operational phase (such as the equalization or increase pressure phase). For example, it could be a pressure condition used to determine whether the system is in a stable operating state, or a pressure threshold used to distinguish different filtration stages.

[0109] The first specific flow condition refers to specific conditions related to liquid flow rate. This could be the liquid velocity, total flow rate, or flow rate fluctuations per unit time detected by the flow detection unit. For example, it might be triggered when the flow rate falls below a certain threshold, indicating that the filter membrane may be clogged. The second specific flow condition refers to another set of specific conditions related to liquid flow rate. This could refer to a specific flow range or flow rate variation pattern required during a specific operational phase (such as forward or reverse motion). For example, it could be used to determine whether the filtration efficiency has reached the expected flow rate conditions, or to adjust the driving force to maintain a constant flow rate.

[0110] Through the above technical solution, this application achieves closed-loop dynamic control of the side-flow filtration process. By using the rotation speed, power, current, and duty cycle of the bidirectional driving unit as execution parameters, the intensity and frequency of fluid delivery can be precisely adjusted from the power source, effectively addressing resistance fluctuations caused by changes in suspension viscosity. Simultaneously, by collecting first specific liquid level conditions, first specific pressure conditions, second specific pressure conditions, third specific pressure conditions, first specific flow rate conditions, and second specific flow rate conditions as condition parameters, the system can perceive the physical state during the filtration process in real time. Using these condition parameters as feedback, the execution parameters can be dynamically adjusted to ensure that the driving force always matches the current fluid resistance at different filtration stages. This mechanism of dynamically changing execution parameters based on real-time monitored condition parameters effectively avoids filter membrane damage due to excessive driving force or filtration stagnation due to insufficient driving force, thus solving the problem that a single drive control parameter cannot adapt to changes in fluid resistance at different stages. This significantly reduces the risk of premature filter membrane clogging and improves filtration efficiency and the stability and continuity of particle collection.

[0111] In some of the solutions described above in this application, the execution parameters of the suspension filtration process are adjusted by a pressure differential step. However, in practical applications, since the viscosity of the suspension increases nonlinearly over time and the degree of particle aggregation has dynamic uncertainty, if only a single pressure boosting strategy is adopted or there is a lack of fine-grained graded control for different working conditions, the filter membrane will be prone to clogging when processing high-viscosity samples, or cause energy waste and excessive sample shearing when processing low-viscosity samples, and it is impossible to achieve adaptive dynamic optimization of the filtration process.

[0112] In response, this application further proposes a side-flow filtration method, in which the differential pressure step has a total of N levels, and the current level of the differential pressure step is the Xth level, where X and N are positive integers, and X is less than or equal to N.

[0113] Specifically, the statement "The differential pressure step has a total of N levels, and the current level of the differential pressure step is the Xth level" indicates that this method subdivides the entire differential pressure operation process into N discrete, adjustable stages or "levels." Here, N is a preset positive integer representing the maximum number of levels in the differential pressure step; for example, N can be set to 3, 5, or more to accommodate suspension samples of varying complexity. X represents the specific level of the currently executing differential pressure step, with a value ranging from 1 to N. This tiered design aims to provide finer pressure control to address the nonlinear changes in suspension viscosity that may occur during filtration.

[0114] In response, this application further proposes a side-flow filtration method, wherein when the differential pressure step is at the Xth level, the differential pressure step is executed according to the specified value of the execution parameter of the differential pressure step at the Xth level.

[0115] "When the differential pressure step is at the Xth gear, the differential pressure step is executed according to the pre-set execution parameters for the Xth gear." This means that for each preset gear X, the system pre-stores a set of corresponding execution parameter values. These execution parameters may include the rotational speed, power, current, and duty cycle of the bidirectional fluid drive unit. When the system determines that the Xth gear should be executed, the controller will automatically call and apply the preset parameters corresponding to that gear to drive the bidirectional fluid drive unit to perform precise pressurization. For example, these specified values ​​can be stored in the controller's memory in the form of a lookup table, or calculated through preset functional relationships.

[0116] In response, this application further proposes a side-flow filtration method, wherein when the condition parameter is lower than the high value threshold of the condition parameter of the Xth gear and higher than the low value threshold of the condition parameter of the Xth gear, the pressure differential step is executed according to the specified value of the execution parameter of the pressure differential step of the Xth gear.

[0117] The core logic for dynamic gear switching is that "if the condition parameter is lower than the high threshold of the condition parameter for the Xth gear and higher than the low threshold of the condition parameter for the Xth gear, then the pressure differential step is executed according to the pre-set execution parameter value of the pressure differential step for the Xth gear." The system continuously monitors a series of condition parameters, such as the first specific liquid level condition, the first specific pressure condition, the second specific pressure condition, the third specific pressure condition, the first specific flow rate condition, and the second specific flow rate condition. For each pressure differential gear X, there is a preset low threshold and a preset high threshold for the condition parameter. When the real-time monitored condition parameter falls within the preset threshold range of a certain gear X, the system will select and execute the pressure differential operation corresponding to that gear X. For example, if the pressure difference across the filter membrane is detected to be at a moderate level, the system may select to execute the pressure differential step for the intermediate gear.

[0118] Furthermore, the high threshold value of the conditional parameter of the Xth gear is not greater than the low threshold value of the conditional parameter of the (X+1)th gear, or the threshold intervals of adjacent gears are continuously connected.

[0119] In response, this application further proposes a side-flow filtration method in which a differential pressure equalization step is performed when the condition parameter is lower than the low threshold of the condition parameter of the first gear.

[0120] "Execute the differential pressure equalization step when the condition parameter is below the low threshold of the first pressure level" is a protective mechanism. When the system detects that the condition parameter (e.g., filtration resistance, differential pressure, or flow fluctuation) is very low, even below the low threshold of the lowest pressure level (i.e., the first level), it indicates that the viscosity of the suspension is extremely low or the membrane permeability is excellent, and no pressure boosting is necessary. To avoid unnecessary energy consumption and excessive shearing of the sample, the system will automatically switch to the differential pressure equalization step for gentle filtration, ensuring the activity and integrity of the sample.

[0121] In response, this application further proposes a side-flow filtration method in which a recovery step is performed when the condition parameter is higher than the high value threshold of the condition parameter of the Nth level.

[0122] The "execute recovery step when conditional parameters exceed the high-value threshold of the Nth pressure level" mechanism is also an important protection and optimization measure. When conditional parameters (e.g., filter resistance, differential pressure, or flow fluctuations) are high enough to exceed the high-value threshold of the highest pressure level (i.e., the Nth pressure level), it usually indicates that the filter membrane may be severely clogged or the system faces excessive pressure risk. In this situation, continuing to increase pressure is not only inefficient but may also damage the filter membrane or equipment. Therefore, the system intelligently triggers the recovery step to change the flow direction or operating mode, attempt to clear blockages, protect the equipment, and recover as much unfiltered sample as possible, thereby avoiding sample loss and equipment failure.

[0123] Through the above technical solution, this application achieves adaptive dynamic optimization of the suspension filtration process. By introducing a multi-level graded control mechanism, the system can dynamically select the most suitable differential pressure level based on real-time monitored parameters, effectively addressing the issues of nonlinear viscosity growth over time and dynamic uncertainty in particle aggregation. Specifically, when the filtration resistance is low, the system can intelligently switch to the differential pressure equalization step, avoiding unnecessary pressurization operations, thus protecting sample activity and reducing energy consumption. As the filtration process progresses and the resistance gradually increases, the system can gradually increase to a higher differential pressure level based on the comparison results of the condition parameters and preset thresholds, ensuring optimal filtration efficiency under different viscosity conditions and effectively preventing filter membrane clogging. Furthermore, when excessively high filtration resistance is detected, reaching the threshold of the highest level, the system can promptly trigger the recovery step, proactively avoiding equipment failure risks and achieving effective sample recovery, significantly improving the robustness and intelligence of the device when processing complex suspensions. This tiered and threshold-triggered mechanism transforms complex fluid dynamics control into a logically clear automated process, ensuring the stability, efficiency, and safety of the filtration and collection process.

[0124] In some of the embodiments described above in this application, it is proposed to adjust the execution parameters of the differential pressure step by using multiple gears to cope with different condition parameters. However, in its actual application, as the system complexity increases, when there are many gears, if the execution parameters and condition parameters only adopt a simple linear correspondence, it is often difficult to accurately match the physical characteristics of the nonlinear growth of suspension viscosity, resulting in the filtration efficiency and system stability not being able to achieve the optimal balance under different operating conditions.

[0125] In this regard, this application further proposes that when N is greater than 3, the relationship between the execution parameters and the condition parameters is non-linear quantization.

[0126] Nonlinear quantization refers to a nonlinear mapping relationship between execution parameters and conditional parameters. That is, the changes in conditional parameters and execution parameters are not simply proportional or have a fixed slope. This relationship can more accurately reflect and adapt to the complex nonlinear changes in the physical properties of suspensions, such as viscosity, during filtration. Specifically, nonlinear quantization can be achieved in several ways, including but not limited to the following: One method is through a pre-defined nonlinear lookup table. This lookup table maps different ranges of conditional parameters (e.g., one or more of the following: first specific liquid level condition, first specific pressure condition, second specific pressure condition, third specific pressure condition, first specific flow rate condition, second specific flow rate condition) to corresponding execution parameters (e.g., one or more of the following: rotational speed, power, current, duty cycle of the bidirectional fluid driving unit) based on extensive experimental data or fluid dynamics models. The mapping relationship in the lookup table is non-uniform; that is, the changes in execution parameters corresponding to adjacent ranges of conditional parameters may differ, thus achieving nonlinear adjustment.

[0127] Another approach is to establish a nonlinear mathematical model. For example, polynomial, exponential, or logarithmic functions can be used to describe the relationship between execution parameters and conditional parameters. Based on the conditional parameters detected in real time, the system calculates the optimal execution parameters using this nonlinear mathematical model. This method provides smoother and more continuous nonlinear adjustment.

[0128] Another approach is to use piecewise functions. The entire range of the condition parameters is divided into multiple sub-intervals, and within each sub-interval, the relationship between the execution parameters and the condition parameters is described using different linear or nonlinear functions. When N is greater than 3, this piecewise function can more precisely approximate complex nonlinear relationships.

[0129] Through the above technical solution, this application can more accurately match the nonlinear changes in the physical properties of suspensions, such as viscosity. In the differential pressure step, when the number of differential pressure levels N is greater than 3, the system is no longer limited to simple linear adjustment, but establishes a nonlinear mapping between the execution parameters and conditional parameters based on the nonlinear change law of suspension viscosity with time and particle aggregation degree. This design allows the execution parameters such as the rotation speed, power, current, or duty cycle of the bidirectional liquid driving unit to better fit the actual needs of fluid dynamics, thereby providing more precise pressure drive in different viscosity ranges. Through this nonlinear quantification, the system can effectively mitigate the risk of filter membrane clogging caused by drastic viscosity changes, ensuring that fluid flow resistance and system pressure fluctuations remain within a controllable range during complex and variable sample processing. This significantly improves the adaptability and operational stability of the device when processing high-viscosity or easily sedimenting suspensions, thereby ensuring the efficiency and accuracy of side-flow filtration.

[0130] In some of the solutions mentioned above in this application, the side-flow filtration process is controlled by dynamically adjusting the execution parameters and condition parameters. However, in practical applications, since the viscosity of the suspension changes nonlinearly over time, it is difficult to accurately capture the subtle changes in the fluid state by relying on a single or coarse parameter feedback. This results in the system being unable to respond to viscosity fluctuations in a timely manner, which in turn leads to filter membrane clogging or a decrease in collection efficiency.

[0131] In this regard, this application further proposes that the execution parameters include one or more of the following: rotational speed, power, current, and duty cycle of the bidirectional fluid driving unit.

[0132] Specifically, the execution parameters are physical quantities used to control the bidirectional fluid driving unit. In the above embodiments, the bidirectional fluid driving unit may include a bidirectional air pump. Therefore, the rotational speed (RPM) refers to the rotational speed of the internal drive motor or pump body of the bidirectional air pump, directly affecting the pump's suction or driving capacity, and thus controlling the fluid delivery rate. Power refers to the electrical power supplied to the bidirectional air pump; adjusting the power can change the pump's operating intensity. Current refers to the current consumed by the bidirectional air pump during operation; its magnitude reflects the pump's load and operating state. Duty cycle is typically used for pulse width modulation (PWM) control; adjusting the duty cycle of the drive signal can precisely control the average output power or rotational speed of the bidirectional air pump. Adjusting these execution parameters allows the system to perform multi-dimensional and refined control of fluid delivery from the power source to adapt to the driving requirements of suspensions of different viscosities. For example, the pumping or driving intensity can be adjusted by changing the motor speed of the bidirectional air pump; or, its output power can be controlled by adjusting the voltage or current supplied to the pump.

[0133] In this regard, this application further proposes that the condition parameters include one or more of the following: a first specific liquid level condition, a first specific pressure condition, a second specific pressure condition, a third specific pressure condition, a first specific flow rate condition, and a second specific flow rate condition.

[0134] Conditional parameters are used to monitor the physical state of the suspension and the progress of the filtration and extraction process in real time.

[0135] In this regard, this application further proposes that the first specific liquid level condition is the first triggering time interval between the first liquid level detection unit and the second liquid level detection unit.

[0136] The first specific liquid level condition, namely the first triggering time interval between the first and second liquid level detection units, is the absolute value of the time difference between the moment the first liquid level detection unit is first triggered (i.e., from no liquid to liquid) and the moment the second liquid level detection unit is first triggered (also from no liquid to liquid). It refers to the time required for the liquid to travel from the first liquid level detection unit to the second liquid level detection unit. The first and second liquid level detection units can employ photoelectric, capacitive, or ultrasonic level sensors, respectively installed at specific locations on the second and third pipelines. By measuring this time interval, the average flow velocity and flow resistance of the fluid in the pipeline can be indirectly assessed, thereby determining whether there is a tendency for excessive viscosity or local blockage. For example, when the liquid level passes through two photoelectric sensors sequentially, the controller records the triggering time of the two sensors and calculates their time difference.

[0137] In this regard, this application further proposes that the first specific pressure condition is the pressure fluctuation of the first pressure sensor per unit time.

[0138] The first specific pressure condition, namely the pressure fluctuation of the first pressure sensor per unit time, refers to the range of change in the pressure value detected by the first pressure sensor connected to the first sample storage unit within a preset time window. The first pressure sensor can be a piezoresistive or capacitive pressure sensor. Large pressure fluctuations may indicate unstable fluid flow, bubble formation, or filter membrane clogging. For example, the controller can acquire pressure data once per second and calculate the standard deviation of the pressure or the difference between the maximum and minimum values ​​over the past 5 seconds.

[0139] In this regard, this application further proposes that the second specific pressure condition is the maximum pressure difference or pressure differential between the first pressure sensor and the second pressure sensor.

[0140] The second specific pressure condition, namely the maximum pressure difference between the first and second pressure sensors, refers to the pressure difference measured between the first pressure sensor connected to the first sample storage unit and the second pressure sensor connected to the second sample storage unit. The second pressure sensor can also be a piezoresistive or capacitive pressure sensor. This pressure difference directly reflects the resistance of the fluid passing through the side-flow filtration unit. An increase in pressure difference usually indicates increased membrane clogging or a significant increase in suspension viscosity. For example, the controller acquires the readings of the two pressure sensors in real time, calculates their difference, and records the maximum difference over a period of time.

[0141] In this regard, this application further proposes that the third specific pressure condition is the pressure rise slope of the first pressure sensor or the second pressure sensor during a single positive motion cycle.

[0142] The third specific pressure condition is the pressure rise slope of the first or second pressure sensor during a single positive motion cycle. An increase in the pressure rise slope usually indicates increased membrane clogging or a significant increase in suspension viscosity.

[0143] In this regard, this application further proposes that the first specific flow condition is the liquid flow rate of the flow detection unit.

[0144] The first specific flow condition, namely the liquid flow rate of the flow detection unit, refers to the instantaneous or average flow rate of the liquid flowing out of the post-membrane chamber of the side-flow filtration unit. The flow detection unit can be a Coriolis mass flow meter or an ultrasonic flow meter. This parameter directly reflects the filtration efficiency. For example, the flow meter outputs flow data in real time, which the controller directly reads and uses to determine the current filtration rate.

[0145] In this regard, this application further proposes that the second specific flow condition is the fluctuation of liquid flow rate of the flow detection unit per unit time.

[0146] The second specific flow condition, namely the liquid flow fluctuation of the flow detection unit per unit time, refers to the range of change in the liquid flow value detected by the flow detection unit within a preset time window. Large flow fluctuations may indicate uneven filter membrane clogging, unstable air pump operation, or drastic changes in fluid characteristics. For example, the controller can collect flow data once per second and calculate the standard deviation of the flow rate or the difference between the maximum and minimum values ​​over the past 10 seconds.

[0147] Through the above technical solutions, this application constructs a multi-dimensional system of execution parameters and condition parameters, realizing refined closed-loop control of the side-flow filtration process. Given the challenge of non-linear and dramatic changes in suspension viscosity over time, relying solely on single or coarse parameter feedback is insufficient to accurately capture subtle changes in fluid state. This application uses the rotation speed, power, current, and duty cycle of the bidirectional driving unit as execution parameters, enabling multi-parameter adjustment of fluid transport from the power source to ensure stable driving force under different viscosity environments. Simultaneously, by introducing the time interval between the first and second liquid level detection units as a liquid level condition, the fluid velocity in the pipeline can be monitored in real time, thereby determining the potential for blockage. Utilizing the pressure fluctuation of the first pressure sensor per unit time and the pressure difference between the first and second pressure sensors as pressure conditions, the stress state on both sides of the filter membrane can be accurately quantified, allowing for timely identification of the degree of filter membrane blockage. Combined with the monitoring of liquid flow rate and its fluctuations by the flow detection unit, the real-time assessment of fluid throughput capacity is further improved. The combined application of these parameters enables the system to dynamically adjust the driving strategy based on the real-time physical characteristics of the suspension, thereby effectively maintaining the stability of the filtration and collection process in environments with drastic viscosity changes. This avoids system failures caused by delayed or isolated parameter feedback, and significantly improves the reliability and accuracy of particle collection.

[0148] In some of the solutions described above in this application, a method for side-flow filtration and sampling is proposed through pressure equalization or pressure increase steps. However, in the actual execution of forward or reverse motion, due to the nonlinear increase of suspension viscosity over time, if there is a lack of real-time monitoring and dynamic intervention mechanism for the fluid motion process, the filter membrane is prone to failure due to excessive clogging, or the system pressure may become abnormal due to excessive fluid transport time, thereby leading to low sample processing efficiency or equipment operation risks.

[0149] In response, this application further proposes that, in the pressure equalization or pressure increase step, when the first liquid level detection unit is triggered for the second time, the forward movement is stopped; and / or, in the pressure equalization or pressure increase step, when the first liquid level detection unit is not triggered for the second time and the duration exceeds a first specific time, the forward movement is stopped; and / or, in the pressure equalization or pressure increase step, when the second liquid level detection unit is triggered for the second time, the reverse movement is stopped; and / or, in the pressure equalization or pressure increase step, when the second liquid level detection unit is not triggered for the second time and the duration exceeds a second specific time, the reverse movement is stopped.

[0150] Specifically, the pressure equalization or pressure boosting step is a crucial stage in the side-flow filtration and sampling method, aiming to achieve effective filtration and collection of particles by controlling the fluid pressure difference. The pressure equalization step is typically used to balance system pressure or perform preliminary fluid exchange, while the pressure boosting step provides sufficient driving force to overcome membrane resistance and achieve effective particle separation. The first liquid level detection unit is a sensor used to monitor the liquid level state of the fluid at a specific pipeline location in real time. It can be implemented using various technologies; for example, an optical liquid level sensor can be used to determine the presence of liquid by detecting changes in the transmission or reflection of a light beam; a capacitive liquid level sensor can be used to detect the liquid level by sensing the difference in dielectric constant between the liquid and air; or an ultrasonic liquid level sensor can be used to determine the liquid level height by measuring the propagation time of ultrasonic waves. Based on the structure of the aforementioned side-flow filtration and sampling device, the first liquid level detection unit is typically located on the second pipeline to monitor the liquid state flowing from the first sample storage unit to the side-flow filtration and sampling unit. The second liquid level detection unit is similar to the first liquid level detection unit, also a sensor used to monitor the liquid level state of the fluid at a specific pipeline location in real time. Its implementation can be the same as the first liquid level detection unit, for example, using sensors based on optical, capacitive, or ultrasonic principles. According to the structure of the aforementioned side-flow filtration and sampling device, the second liquid level detection unit is typically installed on the third pipeline to monitor the liquid state flowing from the side-flow filtration and sampling unit to the second sample storage unit, or to monitor the liquid state flowing from the second sample storage unit to the side-flow filtration and sampling unit during reverse movement. "Being triggered a second time" means that after the liquid level detection unit completes an initial trigger (i.e., first detects that the liquid or liquid level has reached a preset position, i.e., changes from a liquid-free state to a liquid-containing state), it detects the liquid or liquid level reaching that preset position again, meaning that all the liquid has flowed through the liquid level detection unit, changing from a liquid-containing state to a liquid-free state.

[0151] "Forward flow termination" refers to stopping the entire process of liquid flowing from the first sample storage unit to the side-flow filtration and sampling unit, and ultimately to the second sample storage unit. Termination can be achieved by immediately stopping the bidirectional fluid drive unit, thus preventing it from generating forward pressure; or by closing the switching valves on the first and / or fourth pipelines to cut off the fluid passage. "Reverse flow termination" refers to stopping the entire process of liquid flowing from the second sample storage unit to the side-flow filtration and sampling unit, and ultimately to the first sample storage unit. Termination can be achieved by immediately stopping the bidirectional fluid drive unit, thus preventing it from generating reverse pressure; or by closing the switching valves on the first and / or fourth pipelines to cut off the fluid passage.

[0152] The "first specific duration" is a preset time threshold used to limit the duration of forward motion. This duration can be preset based on experimental experience, suspension characteristics, or system performance, and stored in the control system. If, during forward motion, the first liquid level detection unit is not triggered a second time after exceeding this preset duration, the system will determine it as an abnormal situation and forcibly stop the forward motion. The "second specific duration" is a preset time threshold used to limit the duration of reverse motion. Similar to the first specific duration, this duration can also be preset according to the specific application scenario. If, during reverse motion, the second liquid level detection unit is not triggered a second time after exceeding this preset duration, the system will determine it as an abnormal situation and forcibly stop the reverse motion.

[0153] Through the above technical solution, this application introduces a dynamic motion termination mechanism based on the trigger state and time threshold of the liquid level detection unit, effectively solving the system operation risks caused by filter membrane blockage or abnormal fluid transport when processing high-viscosity suspensions. Specifically, for example, in forward motion, when the liquid flows from the first sample storage unit to the side-flow filtration and sampling unit, the first liquid level detection unit will be triggered for the first time (changing from the original liquid-free state to the liquid-containing state). If the liquid continues to flow to the side-flow filtration unit and then to the second sample storage unit, a second trigger (from liquid-containing to liquid-free) will occur when all the liquid has passed through the first liquid level detection unit. This indicates that all the liquid has passed through the first liquid level detection unit, at which point the forward movement is stopped (and the subsequent reverse movement begins). Some liquid remains in the side-flow filtration unit and the third pipeline, reducing the amount of liquid adhering to the second sample storage unit and more effectively utilizing the membrane filtration capacity of the side-flow filtration unit. Otherwise, if all the remaining unfiltered liquid is allowed to flow to the second sample storage unit, the side-flow filtration unit will be unfiltered for a considerable period, reducing filtration efficiency and making the filter cake layer on the side-flow filtration unit more firmly attached, making it harder to be washed away by the reverse filtration step and reducing the subsequent filtration flux. A similar technical principle applies to the reverse movement. Therefore, by monitoring the number of triggers of the liquid level detection unit, the system can determine whether to stop the current filtration step to avoid unnecessary energy consumption or further sedimentation. This closed-loop control strategy significantly improves the automation control accuracy, system robustness, and safety of the sideflow filtration process by providing real-time feedback of liquid level information and making judgments based on the time dimension, ensuring efficient and stable operation under complex fluid conditions.

[0154] In some of the solutions mentioned above in this application, a liquid level detection unit is proposed to monitor the flow state of the suspension to control the filtration process. However, in actual operation, due to the nonlinear increase of the suspension viscosity over time, it is often difficult to accurately determine whether the filter membrane is severely clogged or whether the system has entered a failure state that cannot filter normally, which makes it impossible for the system to switch to the recovery mode in time, resulting in sample waste or low equipment operating efficiency.

[0155] In this regard, this application further proposes that in the side-flow filtration and sampling method, if the time difference between the first liquid level detection unit and the second liquid level detection unit being triggered for the first time during forward motion is greater than a third specific duration, then the triggering condition for the recovery step is met; or, if the time difference between the first liquid level detection unit and the second liquid level detection unit being triggered for the first time during reverse motion is greater than a fourth specific duration, then the triggering condition for the recovery step is met.

[0156] Specifically, the first and second liquid level detection units are sensors used to monitor the real-time changes in the liquid level of the suspension in the pipeline. For example, the first liquid level detection unit can be installed on the second pipeline, and the second liquid level detection unit can be installed on the third pipeline. The implementation methods can include, but are not limited to: using a photoelectric liquid level sensor to determine the liquid level by detecting whether the light beam is blocked by liquid; using a capacitive liquid level sensor to determine the liquid level by detecting changes in the dielectric constant of the liquid; or using an ultrasonic liquid level sensor to determine the liquid level by the reflection time of ultrasonic waves. The "first trigger moment" refers to the instant when the suspension first arrives at or passes through any liquid level detection unit, at which point the detection unit outputs a signal. For example, when the photoelectric sensor detects that the light path is blocked by liquid, the system records a timestamp at this moment. The "time difference" refers to the interval between the first trigger points of two different liquid level detection units, which directly reflects the flow velocity of the suspension in a specific pipeline section. For example, the time interval between these two trigger moments can be accurately recorded and calculated using a timer within the system controller or the timestamp function of a microprocessor. The "third specific duration" and "fourth specific duration" are preset thresholds used to determine whether the suspension flow is abnormal. When the actual measured time difference exceeds these specific durations, it indicates a significant decrease in the suspension flow rate, which may indicate membrane clogging or excessive system resistance. These durations can be dynamically adjusted through experimental calibration, empirical values, or based on the expected viscosity change curve of the suspension. The "recovery step trigger condition" refers to the condition under which the system will automatically initiate the recovery step. The recovery step aims to promptly stop the current filtration and collection process, prevent further membrane clogging or sample loss, and may recover the sample to the storage unit. For example, when the system controller receives a signal that the time difference exceeds the threshold, it immediately sends a command to the bidirectional liquid driving unit to stop its current operation and execute the recovery process.

[0157] Through the above technical solution, this application introduces logical judgment in the time dimension, realizing dynamic evaluation of the flow resistance of the suspension and the state of the filter membrane in the side-flow filtration unit. In forward motion, by monitoring the time difference between the first and second liquid level detection units being triggered, the actual flow velocity of the fluid in the pipeline can be quantified. When this time difference exceeds a preset third specific duration, it means that the fluid flow is significantly obstructed. Based on this, the system automatically triggers a recovery step, thereby protecting the sample in time before irreversible blockage occurs in the filter membrane of the side-flow filtration unit, avoiding sample loss. In reverse motion, by monitoring the time difference between the first and second liquid level detection units being triggered, the smoothness of the fluid in the reverse path can also be verified. When this time difference exceeds a preset fourth specific duration, the system determines that the current filtration environment no longer meets the conditions for continued operation, and thus triggers the recovery step. This time-difference-based triggering mechanism transforms static liquid level detection into dynamic fluid dynamics monitoring, effectively identifying flow lag caused by a sharp increase in suspension viscosity. This ensures that the system can switch to recovery mode in a timely manner when an anomaly is detected, thereby significantly improving the reliability of sample collection and the system's automated processing capabilities. It effectively solves the problems of low filtration efficiency and sample waste caused by changes in suspension viscosity.

[0158] The following example will provide a more detailed explanation of the above technical solution: In a biomedical laboratory setting, researchers need to efficiently and precisely filter target microparticles from a suspension containing nanoscale biological microparticles. During prolonged processing, the viscosity of this suspension increases significantly, easily leading to membrane clogging using traditional filtration methods, thus affecting filtration efficiency and microparticle activity.

[0159] In this example, a side-flow filtration device is used to treat suspensions with high viscosity variation characteristics. The device includes a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a first sample storage unit, a second sample storage unit, a bidirectional liquid displacement unit, and a side-flow filtration unit. The first sample storage unit stores the suspension to be treated, and the second sample storage unit collects the filtered liquid or liquid that has not passed through the side-flow filtration unit. The side-flow filtration unit is the core filtration component, containing an inner cavity and a hydrophilic membrane. The hydrophilic membrane divides the inner cavity into a pre-membrane chamber and a post-membrane chamber, enabling the retention and separation of particles.

[0160] The specific operation process is as follows: First, the suspension to be treated is injected into the first sample storage unit. The eighth port of the bidirectional fluid-driving unit is connected to the first port of the first sample storage unit via a first pipeline, responsible for driving the liquid flow throughout the system. The second port of the first sample storage unit is connected to the third port of the side-flow filtration and sampling unit via a second pipeline, delivering the suspension to the membrane pre-conductor chamber of the side-flow filtration and sampling unit. The fourth port of the side-flow filtration and sampling unit is connected to the fifth port of the second sample storage unit via a third pipeline, guiding the liquid passing through the side-flow filtration and sampling unit to the second sample storage unit. The sixth port of the second sample storage unit is connected to the seventh port of the bidirectional fluid-driving unit via a fourth pipeline, forming a complete circulation path. It is worth noting that no switching valves are installed on the second and third pipelines, which ensures unobstructed bidirectional flow of liquid on both sides of the side-flow filtration and sampling unit, which is crucial for subsequent anti-clogging strategies. Simultaneously, switching valves are installed on the first and fourth pipelines to control the inflow and outflow of liquid and pressure regulation throughout the system.

[0161] To effectively address the problem of filter membrane clogging caused by increased suspension viscosity, the device employs a dynamic side-flow filtration method, which includes a differential pressure equalization step and a differential pressure enhancement step.

[0162] In the initial stage of filtration, the device performs a differential pressure equalization step. The bidirectional liquid driving unit specifically comprises a first three-way valve, a second three-way valve, and a bidirectional air pump. The two outlets of the bidirectional air pump are connected to the normally open ports of the first and second three-way valves, respectively. The common port of the first three-way valve is connected to a first pipeline, and the common port of the second three-way valve is connected to a fourth pipeline. The normally closed ports of the first and second three-way valves are connected to atmospheric pressure. The bidirectional air pump drives the liquid to move forward and backward between the first sample storage unit, the side-flow filtration unit, and the second sample storage unit by alternately generating positive and negative pressures. In the forward movement, the liquid flows from the first sample storage unit to the side-flow filtration unit; a portion of the liquid flows through the membrane of the side-flow filtration unit, and the remaining liquid flows through the side-flow filtration unit and then to the second sample storage unit. In the reverse movement, the liquid flows from the second sample storage unit to the side-flow filtration unit; a portion of the liquid flows through the membrane of the side-flow filtration unit, and the remaining liquid flows through the side-flow filtration unit and then to the first sample storage unit. This forward and reverse motion during the differential pressure equalization step is performed with relatively low and constant execution parameters (e.g., the speed, power, current, or duty cycle of the bidirectional air pump) to ensure uniform distribution of particles on the filter membrane surface and prevent initial localized accumulation. During this stage, a first liquid level detection unit is installed on the second pipeline, and a second liquid level detection unit is installed on the third pipeline to monitor the liquid level in real time, ensuring normal liquid flow within the pipelines. Simultaneously, a first pressure sensor is directly connected to the first sample storage unit, a second pressure sensor is directly connected to the second sample storage unit, and a flow detection unit is used to detect the flow rate exiting the post-membrane chamber. Data from these sensors is used to monitor the system status.

[0163] As the filtration process progresses, the viscosity of the suspension may gradually increase, leading to increased filtration resistance of the filter membrane. This may cause the liquid flow rate detected by the flow detection unit to begin to decrease, or the pressure difference between the first and second pressure sensors to increase. At this point, the device will automatically enter the differential pressure boosting step based on these changes in condition parameters. The differential pressure boosting step also includes forward and / or reverse movement, but its execution parameters are adjusted according to the actual situation. For example, when the liquid flow rate detected by the flow detection unit is lower than the low threshold of a first specific flow condition, the system will switch to the next level of the differential pressure boosting step. The differential pressure boosting step can be divided into multiple levels, each with different condition parameters and execution parameters. For example, when the current level of the differential pressure boosting step is the Xth level, the device will execute the differential pressure boosting step according to the pre-set execution parameters for the Xth level, such as increasing the speed or power of the bidirectional air pump to generate greater driving force and maintain filtration efficiency. This multi-stage differential pressure strategy enables the device to dynamically adjust the driving force according to the nonlinear changes in the suspension viscosity, effectively overcoming membrane clogging and maintaining a stable filtration rate. Compared with traditional fixed-pressure or simple linear pressurization filtration systems, this device significantly extends the service life of the filter membrane and improves the filtration efficiency of high-viscosity suspensions through initial anti-clogging in the differential pressure equalization step and adaptive adjustment in the differential pressure boosting step.

[0164] Throughout the filtration process, the device continuously monitors various condition parameters. For example, the first specific liquid level condition is the first trigger time interval between the first and second liquid level detection units; the first specific pressure condition is the pressure fluctuation of the first pressure sensor per unit time; the second specific pressure condition is the maximum pressure difference or differential pressure between the first and second pressure sensors; and the first specific flow rate condition is the liquid flow rate of the flow detection unit. Real-time feedback of these parameters enables the device to intelligently determine the current filtration status. For example, if the first liquid level detection unit is triggered a second time during forward movement, the forward movement is stopped; or, if the first liquid level detection unit is not triggered a second time for more than a first specific duration, the forward movement is stopped. These mechanisms ensure precise control and safety of the filtration process.

[0165] When filtration is complete or the filter membrane becomes severely clogged, making it impossible to effectively handle via differential pressure (e.g., when the condition parameter exceeds the high threshold of the Nth setting), the device executes a recovery step. The recovery step typically involves only forward motion to efficiently push the liquid in the filtration unit towards the second sample storage unit, completing the final sample collection. For example, during forward motion, if the time difference between the first and second liquid level detection units being triggered is greater than a third specific duration, the recovery step trigger condition is met, and the system initiates the recovery operation.

[0166] Through the synergistic effect of the aforementioned pressure equalization and pressure boosting steps, along with real-time monitoring and feedback control of liquid level, pressure, and flow rate, this suspension side-flow filtration and collection device effectively solves the problems of easy membrane clogging and low efficiency in the filtration and collection process of high-viscosity suspensions. Its bidirectional liquid driving and adaptive pressure regulation mechanism prevents particles from forming a dense filter cake on the membrane surface, thus significantly improving the stability and reliability of filtration and collection. This avoids problems in traditional filtration and collection technologies, such as rapid membrane clogging due to drastic viscosity changes, abnormally increased fluid flow resistance, significant attenuation of sample throughput, and aggravated system pressure fluctuations, ensuring accurate separation and collection of particles.

[0167] The above are merely embodiments of this application and are not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A side-flow filtration and collection device for a suspension, characterized in that, The side-flow filtration and sampling device for the suspension includes a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, a first sample storage unit, a second sample storage unit, a bidirectional liquid displacement unit, and a side-flow filtration and sampling unit. The sideflow filtration and sampling unit also includes an inner cavity and a hydrophilic membrane, which divides the inner cavity into a pre-membrane cavity and a post-membrane cavity. The first sample storage unit includes a first port and a second port. The side-flow filtration and sampling unit includes a third port and a fourth port. The second sample storage unit includes a fifth port and a sixth port. The bidirectional fluid-driving unit includes a seventh port and an eighth port. The eighth port is connected to the first port through the first conduit. The second port is connected to the third port through the second conduit. The fourth port is connected to the fifth port through the third conduit. The sixth port is connected to the seventh port through the fourth conduit. No switching valve is installed on the second pipeline and the third pipeline. A switching valve is provided on the first pipeline and / or the fourth pipeline.

2. A side-flow filtration and sampling device as described in claim 1, characterized in that, The bidirectional fluid driving unit includes a first three-way valve, a second three-way valve, and a bidirectional air pump. The two outlets of the bidirectional air pump are respectively connected to the normally open ends of the first three-way valve and the second three-way valve. The common port of the first three-way valve is connected to the first pipeline. The common port of the second three-way valve is connected to the fourth pipeline. The normally closed ports of the first three-way valve and the second three-way valve are respectively connected to normal pressure.

3. A side-flow filtration and sampling device as described in claim 1, characterized in that, The side-flow filtration and sampling device also includes a first liquid level detection unit and a second liquid level detection unit. And / or, the sideflow filtration and sampling device further includes a first pressure sensor, And / or, the sideflow filtration and sampling device further includes a second pressure sensor. And / or, the sideflow filtration and sampling device further includes a flow detection unit. And / or, the sideflow filtration and sampling device further includes a blocking unit.

4. A side-flow filtration and sampling device as described in claim 3, characterized in that, The first liquid level detection unit is installed on the second pipeline, and the second liquid level detection unit is installed on the third pipeline; And / or, the first pressure sensor is directly connected to the first sample storage unit; And / or, the second pressure sensor is directly connected to the second sample storage unit; And / or, the flow detection unit is used to detect the flow rate exiting the post-membrane cavity; And / or, the blocking unit is disposed on the second pipeline.

5. A method for side-flow filtration and collection of suspension, characterized in that, Sideflow filtration is performed using the sideflow filtration device as described in any one of claims 1-4. The sideflow filtration method includes a differential pressure equalization step and a differential pressure amplification step. The sideflow filtration method includes a recovery step.

6. A side-flow filtration and sampling method as described in claim 5, characterized in that, The execution parameters remain unchanged during the pressure equalization step. And / or, depending on the condition parameters, the execution parameters during the pressure differential increase step are different from those during the pressure differential equalization step. And / or, the pressure differential step is further divided into multiple levels, and in each level of the pressure differential step, the condition parameters are different, and the execution parameters are different.

7. A side-flow filtration and sampling method as described in claim 6, characterized in that, The pressure differential step has a total of N gears, and the current gear in the pressure differential step is the Xth gear, where X and N are positive integers, and X is less than or equal to N. When the condition parameter is lower than the high value threshold of the condition parameter for the Xth gear and higher than the low value threshold of the condition parameter for the Xth gear, the pressure differential step is executed according to the predetermined value of the execution parameter for the pressure differential step of the Xth gear. And / or, when the condition parameter is lower than the low threshold value of the condition parameter in the first gear, the equalization pressure step is executed. And / or, when the condition parameter is higher than the high value threshold of the condition parameter in the Nth gear, the recycling step is performed.

8. A side-flow filtration and sampling method as described in claim 7, characterized in that, When N>3, the execution parameter and the condition parameter have a non-linear quantization relationship.

9. A side-flow filtration and sampling method as described in claim 6, characterized in that, The execution parameters include one or more of the following: rotational speed, power, current, and duty cycle of the bidirectional fluid driving unit. The condition parameters include one or more of the following: a first specific liquid level condition, a first specific pressure condition, a second specific pressure condition, a third specific pressure condition, a first specific flow rate condition, and a second specific flow rate condition.

10. A sideflow filtration and sampling method as described in claim 6, characterized in that, The pressure equalization step includes forward motion and reverse motion. The pressure differential step includes forward motion and / or reverse motion. The recovery step only involves forward motion.

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