An automatic integrated nucleic acid extraction device for large-volume samples

Abstract

The present invention provides a fully automatic integrated nucleic acid extraction device for large-volume samples, which mainly consists of a biological filtration membrane, a nucleic acid adsorption membrane, a sample filtration chamber, a heating membrane, a temperature sensor, an air pump, a first solenoid valve, a second solenoid valve, a waste liquid valve, a stepper motor, a waste liquid chamber, a liquid-phase storage tube, and a microcontroller. Through the biological filtration membrane of the present invention, the organisms to be processed in the large-volume sample are enriched above the filtration membrane, while other impurities and liquids are removed. The heating membrane can accelerate the biological lysis speed, speed up the digestion of proteins by proteinase K, prevent the precipitation of nucleic acid solutions, accelerate the entire nucleic acid extraction speed, reduce organic matter residues, and is fully automatic without manual intervention. The present invention realizes the fully automatic integration of nucleic acid extraction for large-volume samples through the microcontroller, greatly saving labor. At the same time, the nucleic acid extraction process is enclosed in the device to reduce the probability of nucleic acid contamination and the risk of aerosol contamination, and can be applied to the nucleic acid extraction of organisms in water quality and air.

Description

Technical Field

[0001] The present invention belongs to the field of biomedical equipment, and particularly relates to a fully automatic integrated nucleic acid extraction device for large-volume samples, which is used to extract nucleic acids from large-volume biological samples. Background Art

[0002] Since the global outbreak of the COVID-19 pandemic in 2019, molecular diagnostic techniques using nucleic acids for detection have become the gold standard for judging virus infections and an important means for epidemic prevention and control. The extraction of nucleic acids is the first step in molecular diagnosis, which extracts nucleic acids from biological cells or other sample matrices, minimizes the loss of nucleic acid molecules as much as possible, and excludes other contaminants in the samples to ensure the integrity and purity of nucleic acid molecules. Currently, a variety of nucleic acid extraction methods have been developed, mainly including phenol-chloroform extraction method, silica gel membrane extraction method, magnetic bead extraction method, etc. Among them, both the silica gel membrane method and the magnetic bead method utilize the selective adsorption of nucleic acids by solid-phase carriers to adsorb nucleic acids from biological samples, then separate the unbound biological samples from the solid-phase carriers, wash to clean the biological samples remaining on the solid-phase carriers, and finally elute the nucleic acid molecules attached to the solid-phase carriers to achieve nucleic acid extraction. This process involves the addition of biological samples, lysis buffers, washing buffers, elution buffers, as well as mixing and separation with the solid phase, and requires complex operations by professionals and specialized laboratories.

[0003] In order to reduce manual participation and dependence on the laboratory environment, various automated portable nucleic acid extraction devices have been developed in recent years. Main foreign devices include GeneXpert of Cepheid, Filmarray of BioFire, and Cobas Liat of Roche, etc. Main domestic devices include the integrated nucleic acid detection system EasyNAT of Ustar and the Galaxy NanoPCR detector of Aoran Bio, etc. These devices all utilize the magnetic bead method for nucleic acid molecule extraction. The magnetic beads need to be fully mixed with biological samples to adsorb as many free nucleic acid molecules in the samples as possible. However, when extracting nucleic acids from large-volume samples with low content, it is difficult for the magnetic beads to be fully mixed with the large-volume samples, and it is difficult to adsorb all the free DNA in the liquid phase. Therefore, these devices are not suitable for the detection of large-volume samples with low content. For example, during the fight against the COVID-19 pandemic, it was found that there would be aerosol pollution in residential buildings and hospitals, but the detection of aerosol pollution usually enriches viruses in the air using filter membranes; in water quality detection, the content of pathogenic bacteria is usually very low, and filter membranes need to be used to filter water to enrich pathogenic bacteria first. These cases show that when dealing with large-volume samples, the filter membrane, as a solid phase, has a better ability to fully combine with the liquid phase compared to magnetic beads. For the traditional nucleic acid extraction method based on the silica gel membrane method, although large centrifugal columns can be used to extract nucleic acids from large-volume samples, large instruments such as centrifuges and heating devices are required during the extraction process, and multiple operations such as adding, heating, centrifuging, and drying of various liquids need to be carried out manually during the operation. Therefore, the need for a device capable of fully automatic integrated nucleic acid extraction from large-volume samples with low concentration is becoming increasingly urgent. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and provide a fully automatic integrated nucleic acid extraction device for large-volume samples. An air pump is used to provide the driving force for the liquid to flow through the solid phase. By combining a filter membrane with a suitable pore size and a nucleic acid adsorption membrane as the solid phase, filter membranes are used to filter microorganisms such as bacteria, cells, and viruses that need to be intercepted in large-volume biological samples, and then the nucleic acid adsorption membrane is used to extract the nucleic acid molecules after the microorganisms are lysed, so as to achieve the full-automatic extraction of nucleic acid molecules from large-volume biological samples.

[0005] To achieve the above object, a fully automatic integrated nucleic acid extraction device for large-volume samples provided by the present invention mainly consists of a biological filtration membrane, a nucleic acid adsorption membrane, a sample filtration chamber, a heating membrane, a temperature sensor, an air pump, a first solenoid valve, a second solenoid valve, a waste liquid valve, a stepper motor, a waste liquid chamber, a liquid-phase storage tube, and a microcontroller. The biological filtration membrane and the nucleic acid adsorption membrane are stacked in the sample filtration chamber, with the biological filtration membrane placed above the nucleic acid adsorption membrane. The diameters of the biological filtration membrane and the nucleic acid adsorption membrane are the same as the inner diameter of the sample filtration chamber. The heating membrane and the temperature sensor are arranged outside the sample filtration chamber to achieve the heating control of the liquid and the heating control for the volatilization of the residual liquid on the wall surface. The air pump, the first solenoid valve, and the second solenoid valve constitute the main power system of the nucleic acid extraction device - the positive / negative pressure system. The air outlet and the air inlet of the air pump are connected through pipelines and the first solenoid valve and the second solenoid valve. The first solenoid valve is a four-way valve including a p1 air inlet (connected to the air outlet of the air pump), an s1 air outlet (connected to the environment), an s2 air outlet (connected to the waste liquid chamber), and an s3 air outlet (connected to the liquid-phase storage tube). The second solenoid valve is a three-way valve including a p2 air inlet (connected to the air inlet of the air pump), an s4 air outlet (connected to the environment), and an s5 air outlet (connected to the waste liquid chamber). The waste liquid valve is driven by a stepper motor and includes a p3 liquid inlet (connected to the waste liquid chamber), an s6 liquid outlet (for discharging waste liquid), and an s7 liquid outlet (for discharging nucleic acid eluent). The liquid-phase storage tube is connected to the s3 air outlet of the first solenoid valve through a hose. The microcontroller is connected to the heating membrane, the temperature sensor, the air pump, the first solenoid valve, the second solenoid valve, and the stepper motor through wires. The diameters of the biological filtration membrane and the nucleic acid adsorption membrane are the same as the inner diameter of the sample filtration chamber.

[0006] Optionally, the biological filtration membrane includes polymers and biological materials such as cellulose, polytetrafluoroethylene, and polycarbonate.

[0007] Optionally, the biological filtration membrane needs to select filtration membranes with different pore sizes according to the types of samples to be processed (such as bacteria, viruses, cells, etc.). The pore sizes of the biological filtration membrane include 0.22μm, 0.45μm, etc.

[0008] Optionally, the material of the nucleic acid adsorption membrane includes silicon-based materials such as glass fiber and silica gel.

[0009] Optionally, the chamber structure of the waste liquid chamber includes a square shape, a cylindrical shape, a conical shape, etc.

[0010] Optionally, the heating membrane includes a silicone heating membrane, a PI heating membrane, a PET heating membrane, an aluminum foil heating membrane, etc., and the temperature sensor includes a thermal resistance sensor, a thermocouple sensor, etc.

[0011] Optionally, the air pump includes a turbine pump, a vane pump, a piston pump, a diaphragm pump, etc.

[0012] Optionally, the waste liquid valve structure can be a plunger type, a diaphragm type, a ball valve type, etc.

[0013] Optionally, the materials of the pipeline include silica gel, PVC, PTFE, etc.

[0014] Optionally, the materials of the liquid phase storage tube include silica gel, PTFE, etc.

[0015] Optionally, the lysis solution, binding solution, washing solution, and elution solution stored in the liquid phase storage tube can use the related reagents in a commercial kit.

[0016] In the nucleic acid extraction device of the present invention, when the air pump is always on, the positive / negative pressure system can respectively provide a positive pressure to drive the waste liquid to be discharged into the waste liquid chamber, provide a positive pressure to drive the reagent to enter the sample filtration chamber 3 in the liquid phase storage tube, and provide a negative pressure to drive the liquid in the sample filtration chamber to pass through the biological filtration membrane and the nucleic acid adsorption membrane by controlling the opening and closing of the air outlets s2, s3, and s5 of the first solenoid valve and the second solenoid valve.

[0017] When the air outlets s2 and s3 of the first solenoid valve are opened, the air outlet s4 of the second solenoid valve also needs to be opened to maintain the pressure balance in the air path channel.

[0018] When the air outlet s5 of the second solenoid valve is opened, the air outlet s1 of the first solenoid valve also needs to be opened to maintain the pressure balance in the air path channel.

[0019] The waste liquid valve can connect the p3 liquid inlet to the s6 liquid outlet or connect the p3 liquid inlet to the s7 liquid outlet by controlling the stepping motor.

[0020] The lysis solution, binding solution, washing solution, and elution solution are pre-stored in the liquid phase storage tube 12, and adjacent liquids are separated by air.

[0021] The present invention has the following beneficial effects:

[0022] (1) Enrich the object to be measured: Through the biological filtration membrane 1, the organisms to be processed in the large-volume sample are enriched above the filtration membrane, and other impurities and liquids are removed;

[0023] (2) Accelerate the nucleic acid extraction process: The heating film 5 on the surface of the sample filtration chamber can accelerate the biological lysis speed, accelerate the speed of proteinase K digesting proteins, prevent the precipitation of the nucleic acid solution, and accelerate the entire nucleic acid extraction speed;

[0024] (3) Reduce the organic matter residue: The heating film 5 can heat the surface of the filtration chamber, the biological filtration membrane 1, and the nucleic acid adsorption membrane 2, so that the organic matter on the surface volatilizes as much as possible, reducing the content of organic impurities in the downstream nucleic acid elution product;

[0025] (4) Fully automatic without manual intervention: By controlling each component through a microcontroller, the entire nucleic acid extraction process can be automatically completed, reducing manual intervention;

[0026] (5) No risk of aerosol contamination: The sample filtration chamber is mostly under negative pressure, so gas will not diffuse outside the filtration chamber, reducing the risk of aerosol contamination. When the system is under positive pressure, due to the obstruction of the filter membrane, the gas preferentially discharges from the waste liquid valve. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of the present invention.

[0028] Figure 2 It is a schematic diagram of the control method of the positive / negative pressure system of the main power components in the present invention.

[0029] Figure 3 It is a schematic diagram of the structure and control method of the waste liquid valve in the present invention.

[0030] Description of the reference numerals:

[0031] 1 - Biological filter membrane; 2 - Nucleic acid adsorption membrane; 3 - Sample filtration chamber; 4 - Heating membrane; 5 - Temperature sensor; 6 - Air pump; 7 - First solenoid valve; 8 - Second solenoid valve; 9 - Waste liquid valve; 10 - Stepper motor; 11 - Waste liquid chamber; 12 - Liquid phase storage tube; 13 - Microcontroller. Detailed Description of the Invention

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0033] Embodiment 1

[0034] See Figure 1, A fully automatic integrated nucleic acid extraction device for large-volume samples, mainly composed of a biological filtration membrane 1, a nucleic acid adsorption membrane 2, a sample filtration chamber 3, a heating membrane 4, a temperature sensor 5, an air pump 6, a first solenoid valve 7, a second solenoid valve 8, a waste liquid valve 9, a stepper motor 10, a waste liquid chamber 11, a liquid-phase storage tube 12, and a microcontroller 13. In the sample filtration chamber 3, the biological filtration membrane 1 and the nucleic acid adsorption membrane 2 are stacked. The biological filtration membrane 1 and the nucleic acid filtration membrane are of the same size and stacked on top of each other. Among them, the nucleic acid adsorption membrane 2 is fixed below the biological filtration membrane 1. The biological filtration membrane 1 can capture organisms in the sample through its pore size, and the nucleic acid adsorption membrane 2 can adsorb free nucleic acid molecules after the organisms are lysed. The sample filtration chamber 3 provides a certain volume for storing samples, lysis solutions, washing solutions, elution solutions, etc. The mutually stacked biological filtration membrane 1 and nucleic acid adsorption membrane 2 are placed at the bottom of the sample filtration chamber 3. The diameters of the biological filtration membrane 1 and the nucleic acid adsorption membrane 2 are the same as the inner diameter of the sample filtration chamber 3 and are closely attached to the inside of the sample filtration chamber 3. The heating membrane 4 and the temperature sensor 5 are attached to the outside of the sample filtration chamber 3, and the attachment is achieved by applying silicone grease for close attachment. The heating membrane 4 is used to heat the sample filtration chamber 3. Heating is required during the lysis of organisms and before eluting nucleic acids to dry the sample filtration chamber 3, the biological filtration membrane 1, and the nucleic acid adsorption membrane 2. The temperature sensor 5 is used to detect the temperature of the heating membrane and provide feedback for the heating control of the heating membrane 4. The heating membrane 4 and the temperature sensor 5 are connected to the microcontroller 13 through wires, and precise temperature control is achieved through a program.

[0035] The waste liquid chamber 11 is used to store the waste liquid filtered from the sample filtration chamber 3. The upper part of the waste liquid chamber 11 is connected to the sample filtration chamber 3, the lower part of the waste liquid chamber 11 is connected to the waste liquid valve 9, and the side of the waste liquid chamber 11 is connected to the first solenoid valve 7 and the second solenoid valve 8.

[0036] The waste liquid valve 9 includes an inlet p3 (connected to the waste liquid chamber 11), an outlet s6 (for discharging waste liquid), and an outlet s7 (for discharging nucleic acid elution liquid). The waste liquid valve 9 has two working states: when the inlet p3 is connected to the outlet s6, the waste liquid in the waste liquid chamber 11 will be discharged through the outlet s6; when the inlet p3 is connected to the outlet s7, the elution liquid in the waste liquid chamber 11 will be discharged through the outlet s7. The switching of the two working states of the waste liquid valve 9 is driven by the stepper motor 10. The stepper motor 10 is connected to the microcontroller 13 through wires, and the switching of the working state of the waste liquid valve 9 is achieved through a program.

[0037] The air pump 6, the first solenoid valve 7, and the second solenoid valve 8 constitute a power system capable of realizing positive / negative pressure switching - the positive / negative pressure system. The air pump 6 is an air pump with an air inlet and an air outlet, capable of continuous operation. The first solenoid valve 7 is a four-way valve including an air inlet p1 (connected to the air outlet of the air pump 6), an air outlet s1 (connected to the environment), an air outlet s2 (connected to the waste liquid chamber 11), and an air outlet s3 (connected to the liquid phase storage tube 12). The second solenoid valve 8 is a three-way valve including an air inlet p2 (connected to the air inlet of the air pump 6), an air outlet s4 (connected to the environment), and an air outlet s5 (connected to the waste liquid chamber 11). The air outlet and air inlet of the air pump 6 are connected to the air inlet p1 of the first solenoid valve 7 and the air inlet p2 of the second solenoid valve 8 through pipelines; the air outlet s2 of the first solenoid valve 7 is connected to the waste liquid chamber 11, the air outlet s1 is connected to the environment for balancing the atmospheric pressure, and the air outlet s3 is connected to the liquid phase storage tube 12 for discharging the liquid in the tube; the air outlet s5 of the second solenoid valve 8 is connected to the waste liquid chamber 11, and the air outlet s4 is connected to the environment for balancing the atmospheric pressure. The air pump 6, the first solenoid valve 7, and the second solenoid valve 8 are connected to the microcontroller through wires for control. The first solenoid valve 7 has three working states: the air inlet p1 is connected to the air outlet s1 for balancing the atmospheric pressure; the air inlet p1 is connected to the air outlet s2 for providing positive pressure to the waste liquid chamber 11; the air inlet p1 is connected to the air outlet s3 for providing positive pressure to the liquid phase storage tube 12 to discharge the liquid. The second solenoid valve 8 has two working states: the air inlet p2 is connected to the air outlet s4 for balancing the atmospheric pressure; the air inlet p2 is connected to the air outlet s4 for providing negative pressure to the waste liquid chamber 11.

[0038] The liquid phase storage tube 12 stores reagents for biological lysis such as lysis buffer, binding buffer, washing buffer, and elution buffer. These reagents are stored in amounts ranging from 200 μL to 600 μL according to the usage amount, and adjacent reagents are separated by air to prevent mixing. The liquid phase storage tube is connected to the air outlet s3 of the first solenoid valve 7 and can discharge the stored liquid through the control of the microcontroller 13.

[0039] Example 2

[0040] See Figure 1 , the control process of each component according to the nucleic acid extraction process is as follows:

[0041] 1. Directly add the sample into the sample filtration chamber, close the waste liquid valve 9, turn on the air pump 6, connect the p1 port of the first solenoid valve 7 to the s1 port, and connect the p2 port and s5 port of the second solenoid valve 8 to provide negative pressure to the sample filtration chamber 3. Cells, bacteria, viruses, etc. in the sample will be intercepted by the biological filter membrane 1, and the liquid in the sample will enter the waste liquid chamber 11 through the filtration chamber.

[0042] 2. Subsequently, connect the p1 port of the first solenoid valve 7 to the s3 port, and connect the p2 port and s4 port of the second solenoid valve 8 to provide a positive pressure to the liquid phase storage tube 12, and push the lysis solution into the sample filtration chamber 3.

[0043] 3. Then, turn off the air pump 6, turn on the heating film 4, and use the temperature sensor 5 to stably provide an appropriate temperature for lysis to the sample filtration chamber 3, and heat for 10 minutes.

[0044] 4. After lysing for a period of time, turn off the heating film 4, turn on the air pump 6, connect the p1 port of the first solenoid valve 7 to the s3 port, and connect the p2 port and s4 port of the second solenoid valve 8 to provide a positive pressure to the liquid phase storage tube 12, and push the binding solution into the sample filtration chamber to adsorb the nucleic acid molecules on the nucleic acid adsorption membrane 2.

[0045] 5. Subsequently, connect the p1 port of the first solenoid valve 7 to the s1 port, and connect the p2 port and s5 port of the second solenoid valve 8 to provide a negative pressure to the sample filtration chamber 3, so that the excess liquid enters the waste liquid chamber 11.

[0046] 6. Then, connect the p1 port of the first solenoid valve 7 to the s3 port, and connect the p2 port and s4 port of the second solenoid valve 8 to provide a positive pressure to the liquid phase storage tube 12, and push the cleaning solution into the sample filtration chamber 3.

[0047] 7. Subsequently, connect the p1 port of the first solenoid valve 7 to the s1 port, and connect the p2 port and s5 port of the second solenoid valve 8 to provide a negative pressure to the sample filtration chamber 3, and let the cleaning solution flow through the biological filtration membrane 1 and the nucleic acid adsorption membrane 2 to remove the excess impurities.

[0048] 8. Repeat the above steps 6 and 7 once.

[0049] 9. Turn off the air pump 6, control the stepper motor 10 to open the waste liquid valve 9, connect the p3 port to the s6 port, connect the p1 port of the first solenoid valve 7 to the s2 port, and connect the p2 port and s4 port of the second solenoid valve 8, turn on the air pump 6, provide a positive pressure to the waste liquid chamber 11, discharge the waste liquid and turn on the heating film 4 to heat the sample filtration chamber 3 to volatilize the organic matter on the wall surface and the membrane, for 2 minutes.

[0050] 10. Subsequently, connect the p1 port of the first solenoid valve 7 to the s3 port, and connect the p2 port and s4 port of the second solenoid valve 8 to provide a positive pressure to the liquid phase storage tube 12, and push the elution solution into the sample filtration chamber 3, turn off the air pump 6, and incubate at room temperature for 5 minutes.

[0051] 11. Connect the p1 port of the first solenoid valve 7 to the s1 port, and connect the p2 port and s5 port of the second solenoid valve 8, turn on the air pump 6, provide a negative pressure to the sample filtration chamber, and pump the elution solution into the waste liquid chamber 11.

[0052] 12. Turn off the air pump 6, control the stepper motor 10 to open the waste liquid valve 9, connect the p3 port to the s7 port, connect the p1 port of the first solenoid valve 7 to the s2 port, connect the p2 port and the s4 port in the second solenoid valve 8, turn on the air pump 6, and provide positive pressure to the waste liquid chamber 11, then the nucleic acid eluent can be exported from the s7 port.

[0053] Example 3

[0054] See Figure 2 , the core power source of this fully automatic integrated nucleic acid extraction device for large-volume samples is a power system that can switch between positive / negative pressure. When the liquid-phase storage tube 12 is not considered, this system only needs to include an air pump, two solenoid valves and a three-way valve. The air pump has an air inlet and an air outlet, which are respectively connected to the air inlet I1 of the solenoid valve 1 and the air inlet I2 of the solenoid valve 2. The air outlet O1 of the solenoid valve 1 and the air outlet O4 of the solenoid valve 2 are connected to the environment. The air outlet O2 of the solenoid valve 1 and the air outlet O3 of the solenoid valve 2 are connected to the waste liquid chamber through a three-way valve. The on / off of the air outlet of the solenoid valve is triggered by a voltage signal. When the trigger signal is at a low level, the solenoid valve does not work; when the trigger signal is at a high level, the solenoid valve works and the air inlet is connected to this air outlet. When negative pressure needs to be provided to the waste liquid chamber, O1 of the solenoid valve 1 is at a high level, O2 is at a low level, I1 is connected to O1 to balance the air pump pressure; O3 of the solenoid valve 2 is at a high level, O4 is at a low level, I2 is connected to O3 to connect the air inlet of the air pump to the waste liquid chamber. When positive pressure needs to be provided to the waste liquid chamber, O1 of the solenoid valve 1 is at a low level, O2 is at a high level, I1 is connected to O2 to connect the air outlet of the air pump to the waste liquid chamber; O3 of the solenoid valve 2 is at a low level, O4 is at a high level, I2 is connected to O4 to balance the air pump pressure.

[0055] Example 4

[0056] See Figure 3, the waste liquid valve 9 is a four-way structure valve body, connected to the plunger on the left, connected to a cam driven by a stepper motor, with a waste liquid port on the right, connected to the waste liquid chamber 11 above, and an eluent port below. The waste liquid valve needs to achieve three states: closed, connecting the waste liquid chamber and the waste liquid port, and connecting the waste liquid chamber and the eluent port. Correspondingly, the radius of the cam is designed in three sizes, namely r1, r2, and r3. These three sizes correspond to the travel distance of the plunger in the waste liquid valve body. By controlling the rotation of the stepper motor, precise movement of the plunger in the waste liquid valve can be achieved. The specific implementation method is as follows: The initial state of the stepper motor is state 1. At this time, the plunger closes the inlet connecting the upper part and the waste liquid chamber, and the positive / negative pressure system can be used to perform suction filtration on the sample filtration chamber; controlling the stepper motor to rotate 90° can reach state 2. In this state, the waste liquid chamber is connected to the waste liquid port, and the waste liquid in the waste liquid chamber can be discharged under the action of positive pressure; controlling the stepper motor to rotate 180° can reach state 3. In this state, the waste liquid chamber is connected to the eluent port, and the eluent is discharged under the action of positive pressure. Precise control of the three states of the valve body can be achieved by controlling the rotation angle of the stepper motor.

[0057] In the specific embodiments described above, the purpose, technical solutions, and beneficial effects of the present invention have been further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An automatic integrated nucleic acid extraction device for large-volume samples, characterized in that, It consists of a biological filtration membrane (1), a nucleic acid adsorption membrane (2), a sample filtration chamber (3), a heating membrane (4), a temperature sensor (5), an air pump (6), a first solenoid valve (7), a second solenoid valve (8), a waste liquid valve (9), a stepper motor (10), a waste liquid chamber (11), a liquid phase storage tube (12), and a microcontroller (13). The biological filtration membrane (1) and the nucleic acid adsorption membrane (2) are stacked in the sample filtration chamber (3), with the biological filtration membrane (1) placed above the nucleic acid adsorption membrane (2). The heating membrane (4) and the temperature sensor (5) are arranged outside the sample filtration chamber (3). The air pump (6), the first solenoid valve (7), and the second solenoid valve (8) constitute the main power system of the nucleic acid extraction device - the positive / negative pressure system. The air outlet and the air inlet of the air pump (6) are connected to the first solenoid valve (7) and the second solenoid valve (8) through pipelines. The liquid phase storage tube (12) is connected to the first solenoid valve (7) through a hose. The microcontroller (13) is connected to the heating membrane (4), the temperature sensor (5), the air pump (6), the first solenoid valve (7), the second solenoid valve (8), and the stepper motor (10) through wires; Among them, the first solenoid valve (7) is a four-way valve with a p1 air inlet, an s1 air outlet, an s2 air outlet, and an s3 air outlet respectively. The second solenoid valve (8) is a three-way valve with a p2 air inlet, an s4 air outlet, and an s5 air outlet respectively. The waste liquid valve (9) is driven by the stepper motor (10). The waste liquid valve (9) includes a p3 liquid inlet, an s6 liquid outlet, and an s7 liquid outlet. The p1 air inlet of the first solenoid valve (7) is connected to the air outlet of the air pump (6), the s1 air outlet is connected to the environment, the s2 air outlet is connected to the waste liquid chamber (11), and the s3 air outlet is connected to the liquid phase storage tube (12). The p2 air inlet of the second solenoid valve (8) is connected to the air inlet of the air pump (6), the s4 air outlet is connected to the environment, and the s5 air outlet is connected to the waste liquid chamber (11). The liquid phase storage tube (12) is connected to the s3 air outlet of the first solenoid valve (7) through a hose; Among them, the p3 liquid inlet of the waste liquid valve (9) is connected to the waste liquid chamber (11), the s6 liquid outlet is used for discharging waste liquid, and the s7 liquid outlet is used for discharging nucleic acid eluate.

2. The nucleic acid extraction device according to claim 1, wherein The diameters of the biological filtration membrane (1) and the nucleic acid adsorption membrane (2) are the same as the inner diameter of the sample filtration chamber (3).

3. The nucleic acid extraction device according to claim 1, characterized in that, The biological filtration membrane is selected from cellulose, polytetrafluoroethylene, or polycarbonate.

4. The nucleic acid extraction device according to claim 1, characterized in that The material of the nucleic acid adsorption membrane (2) is selected from glass fiber or silica gel.

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