A system for extracting cell-free DNA

Abstract

The application belongs to the technical field of DNA extraction, and particularly relates to a free DNA extraction system, which comprises a power system, a rotating system and a test tube. The power system comprises a shell, a top cover and a power box. The rotating system comprises a rotating disc, a first channel, a first push rod, a second push rod, a first spring, a second channel, a rotating shaft and a sample groove. In the process of covering the top cover, the top rod moves downward in the first channel, and then is pressed between the gaps of the two balls. The balls roll, the first push rod moves away from the first channel, and the first spring is compressed. The bottom of the test tube is in contact with the top of the second push rod but not with the arc-shaped convex block, so that the test tube moves downward. When the top cover is opened, the top rod moves away from the gap between the two balls, and the first spring is reset. The second push rod and the first push rod are pushed to move towards the first channel, and the bottom of the test tube is in contact with the arc-shaped convex block, so that the test tube is exposed more from the sample groove, and the test tube is convenient to take out.

Description

Technical Field

[0001] This invention belongs to the field of DNA extraction technology, specifically a system for extracting free DNA. Background Technology

[0002] DNA is one of the four major biological macromolecules found in biological cells, specifically nucleic acids. DNA carries the genetic information necessary for the synthesis of RNA and proteins, and is an essential biological macromolecule for the development and normal functioning of organisms. Current DNA extraction techniques adhere to the following principles: first, ensuring the integrity of the primary structure of nucleic acids; second, the presence of organic solvents that inhibit enzymes and excessively high concentrations of metal ions in the nucleic acid sample; third, minimizing contamination from other biological macromolecules such as proteins, polysaccharides, and lipids; and fourth, removing other nucleic acid molecules, such as RNA, as much as possible.

[0003] In existing technologies, one method for extracting cell-free DNA is the centrifugation column method. The centrifugation column contains a silica gel membrane. Plasma is centrifuged, passing through the column and the silica gel membrane. Due to the specific properties of the silica gel membrane, cell-free DNA in the plasma is adsorbed by the membrane, while other substances pass through. This completes the separation of cell-free DNA from the plasma. Subsequent washing steps separate the DNA from the silica gel membrane. However, this process has drawbacks. All steps rely on centrifugation, and the number of centrifugations is high. The test tubes used in this process are mostly small, and during centrifugation, only a small portion of the tube protrudes, making removal after centrifugation inconvenient. The need for multiple centrifugations also impacts the work efficiency of the staff.

[0004] In view of this, the present invention provides a free DNA extraction system to solve the above-mentioned technical problems. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies and solve the problem of difficulty in removing test tubes during centrifugation for free DNA extraction, this invention provides a free DNA extraction system.

[0006] The technical solution adopted by this invention to solve its technical problem is: a free DNA extraction system, including a power system, a rotation system, and test tubes; the power system includes a shell, a top cover, and a power box; the power box is fixedly installed at the bottom of the shell, the top cover is movably connected to the top of the shell via threads, and a push rod is provided at the center of the bottom of the top cover; the rotation system includes a turntable, a first channel, a first push rod, a second push rod, a first spring, a second channel, a rotating shaft, and a sample slot; a rotating shaft is fixedly provided at the center of the bottom of the turntable, and the turntable is connected to the inside of the power box via the rotating shaft. The turntable has a first channel at its center; a second channel is horizontally arranged near the bottom inside the turntable, and a push rod is embedded in the end of the second channel near the first channel. A ball bearing is nested in the end of the first push rod near the first channel; the other end of the first push rod is fixedly connected to the side of the second push rod; the top of the second push rod has an arc-shaped protrusion, and the end of the second push rod near the outer wall of the turntable is fixedly connected to the outer wall of the turntable near the side by a first spring; a sample slot is inclinedly arranged near the side wall of the turntable, and the sample slot communicates with the second channel.

[0007] During operation, the turntable contains multiple sample slots, a second channel, a first pusher, a second pusher, and a first spring. All sample slots, second channels, first pushers, second pushers, and first springs are symmetrical about the central axis of the turntable. A centrifugal purification column for DNA extraction is fixed inside a test tube, and a suitable amount of treated plasma is injected into the tube. The test tube is then capped and placed in a sample slot; this is the initial state of the device, with the bottom of the test tube resting against the arc-shaped protrusion. The top cap is then placed on top. During this process, the pusher moves downwards within the first channel and then reaches the gap between two ball bearings. Because the gap between the two ball bearings is smaller than the diameter of the pusher, the ball bearings roll, causing the first pusher to move away from the first channel. Therefore, the first pusher pushes the second pusher horizontally away from the first channel, and the first spring... The test tube is compressed; when the top cover is fully closed, the bottom of the test tube contacts the top of the second push rod but not the arc-shaped protrusion, so the test tube will move downwards and enter the sample cell deeper, making centrifugation more stable and safe; then the centrifugation process begins. During centrifugation, because the push rod is cylindrical, the ball bearings roll along the side wall of the push rod, and the push rod does not contact the bottom of the first channel, so it does not affect the centrifugation process; after the centrifugation process is completed, the top cover is opened; when the top cover is opened, the push rod moves away from the gap between the two ball bearings, and then the first spring returns to its original position, pushing the second push rod and the first push rod to move towards the first channel. When the first spring returns to its original position, that is, when the second push rod stops moving, the bottom of the test tube just contacts the arc-shaped protrusion. During this process, due to the change in the height of the bottom of the test tube, the test tube will be pushed out a certain distance, that is, the test tube will be exposed more of the sample cell, making it easier to remove the test tube.

[0008] Preferably, a plurality of No. 1 rollers are evenly arranged on the side wall of the sample cell, and the No. 1 rollers are rotatably connected to the side wall of the sample cell; and the wheel surface of the No. 1 rollers is in contact with the outer surface of the side wall of the test tube.

[0009] During operation, several No. 1 rollers are evenly arranged on the side wall of the sample cell, and the wheel surface of the No. 1 rollers is in contact with the outer surface of the side wall of the test tube. During the loading and unloading of the test tube, the movement of the test tube causes the No. 1 rollers to rotate. This arrangement changes sliding friction into rolling friction, which facilitates the removal of the test tube. Furthermore, during the movement of the No. 2 push rod, the presence of the No. 1 rollers makes it easier for the test tube to move along the sample cell, avoiding the situation where the test tube gets stuck in the sample cell. This also prevents the No. 2 push rod from breaking the test tube during its movement due to the test tube getting stuck.

[0010] Preferably, the end of the second push rod closest to the first channel is rotatably connected to a second roller.

[0011] During operation, a second roller is installed at the end of the second push rod closest to the first channel. Since the second roller is located at the end of the second push rod, and the first push rod is connected to its side, the first push rod does not affect the rotation of the second roller. When the centrifuge is working, the bottom of the test tube is in contact with the surface of the second roller. Since vibration is inevitable during centrifugation, this design reduces the contact area between the bottom of the test tube and the second push rod, thus reducing mutual vibration and preventing the bottom of the test tube from breaking due to severe vibration. Furthermore, the rotation of the second roller causes the bottom of the test tube to move relative to the upper surface of the second push rod under its influence. Compared to having no second roller, this design makes relative movement of the test tube on the second push rod easier, reducing the likelihood of the test tube getting stuck and increasing the operability of the device.

[0012] Preferably, the bottom of the arc-shaped protrusion is provided with a limiting groove, a limiting block is embedded in the limiting groove, the limiting block is fixed on the second push rod, and a second spring is provided on the top of the limiting block.

[0013] During operation, a limiting groove is provided at the bottom of the arc-shaped protrusion, and a limiting block is embedded in the limiting groove. The limiting block is fixed on the second push rod, and a second spring is provided at the top of the limiting block. When the centrifuge is working, the second spring is in a compressed state. When the centrifugation is finished and the top cover is opened, the arc-shaped protrusion moves to the sample slot port, the second spring resets, and the arc-shaped protrusion moves along the limiting block. This process causes the arc-shaped protrusion to push the bottom of the test tube, making more of the test tube exposed in the sample slot, which makes it easier to remove the test tube.

[0014] Preferably, the connection between the first push rod and the ball is a conical surface.

[0015] During operation, the conical surface at the connection between the push rod and the ball bearings makes it easier for the push rod to be inserted between the two ball bearings compared to a design without a conical surface, ensuring the normal operation of the device. Furthermore, the conical surface ensures that during centrifugation, it will not contact the push rod; only the ball bearings will contact the push rod, preventing wear on the device. After centrifugation, when the top cover is opened, the push rod moves out from between the two ball bearings, and the push rod resets. During reset, the conical surface design ensures that the side wall of the push rod does not contact the push rod, allowing the push rod to move out smoothly.

[0016] Preferably, the first roller, the second roller, and the arc-shaped protrusion are all made of rubber.

[0017] During operation, the first roller is made of rubber, which prevents the test tube from breaking due to collision with the side wall of the sample tank during removal. The second roller and the arc-shaped protrusion are also made of rubber, which prevents the bottom of the test tube from breaking due to collision between the second roller and the arc-shaped protrusion and the bottom of the test tube during the movement of the second push rod, thus increasing the safety of the device.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. The cell-free DNA extraction system of the present invention, during the process of closing the top cover, the push rod moves down in the first channel and then pushes against the gap between the two ball bearings. The ball bearings roll, and the first push rod moves away from the first channel, compressing the first spring. The bottom of the test tube is in contact with the top of the second push rod but not with the arc-shaped protrusion, so the test tube will move down. When the top cover is opened, the push rod moves away from the gap between the two ball bearings, and then the first spring returns to its original position, pushing the second push rod and the first push rod to move towards the first channel. The bottom of the test tube just contacts the arc-shaped protrusion, so that more of the sample slot is exposed, making it easier to remove the test tube.

[0020] 2. The cell-free DNA extraction system of the present invention, by setting a second roller, the rotation of the second roller causes the bottom of the test tube to move relative to the upper surface of the second push rod under the drive of the second roller. Compared with the absence of the second roller, this setting makes it easier for the test tube to move relative to the second push rod, thus making it less likely for the test tube to get stuck, and increasing the operability of the device. Attached Figure Description

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] Figure 1 This is a cross-sectional view of the present invention during centrifugation;

[0023] Figure 2 yes Figure 1 A magnified view of a portion at point A;

[0024] Figure 3 yes Figure 1 A magnified view of a portion at point B;

[0025] Figure 4 This is a cross-sectional view of the present invention after centrifugation;

[0026] Figure 5 yes Figure 4 A magnified view of a portion at point C;

[0027] In the diagram: Power system 1, Rotation system 2, Test tube 3, Shell 11, Top cover 12, Power box 13, Turntable 21, Channel 1 22, Push rod 1 23, Push rod 24, Spring 1 25, Channel 2 26, Shaft 27, Sample slot 28, Push rod 121, Ball bearing 231, Arc-shaped protrusion 241, Roller 242, Limiting groove 243, Limiting block 244, Spring 245, Roller 281. Detailed Implementation

[0028] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0029] like Figures 1 to 5 As shown, the present invention discloses a free DNA extraction system comprising a power system 1, a rotation system 2, and test tubes 3. The power system 1 includes a housing 11, a top cover 12, and a power box 13. The power box 13 is fixedly installed at the bottom of the housing 11. The top cover 12 is movably connected to the top of the housing 11 via threads, and a push rod 121 is provided at the center of the bottom of the top cover 12. The rotation system 2 includes a turntable 21, a first channel 22, a first push rod 23, a second push rod 24, a first spring 25, a second channel 26, a rotating shaft 27, and a sample slot 28. The rotating shaft 27 is fixedly installed at the center of the bottom of the turntable 21, and the turntable 21 is connected to the inside of the power box 13 via the rotating shaft 27. A first channel 22 is provided at the center of the disk 21; a second channel 26 is horizontally provided near the bottom inside the rotating disk, and a first push rod 23 is embedded in the end of the second channel 26 near the first channel 22. A ball bearing 231 is nested in the end of the first push rod 23 near the first channel 22; the other end of the first push rod 23 is fixedly connected to the side of the second push rod 24; the top of the second push rod 24 is provided with an arc-shaped protrusion 241, and the end of the second push rod 24 near the outer side wall of the rotating disk 21 is fixedly connected to the position of the rotating disk 21 near the outer side wall by a first spring 25; a sample groove 28 is inclinedly provided in the part of the rotating disk 21 near the side wall, and the sample groove 28 communicates with the second channel 26.

[0030] During operation, the turntable 21 is equipped with multiple sample slots 28, a second channel 26, a first push rod 23, a second push rod 24, and a first spring 25. All sample slots 28, second channels 26, first push rods 23, second push rods 24, and first springs 25 are symmetrical about the central axis of the turntable 21. A centrifugal purification column for DNA extraction is fixedly installed inside test tube 3, and a suitable amount of treated plasma is injected into test tube 3. The test tube 3 is then capped and placed into the sample slot 28. In the initial state of the apparatus, the bottom of test tube 3 rests against the arc-shaped protrusion 241; then the top cover 12 is closed. During the closing of the top cover 12, the push rod 121 moves downward within the first channel 22 and then pushes against the gap between the two balls 231. Since the width of the gap between the two balls 231 is smaller than the diameter of the push rod 121, the balls 231 roll, and the first push rod 23 moves away from the first channel 22. Therefore, the first push rod 23 pushes the second push rod 24 to move horizontally away from the first channel 22. Spring 25 is compressed; when the top cover 12 is fully closed, the bottom of test tube 3 contacts the top of push rod 24 but not the arc-shaped protrusion 241, so test tube 3 will move downward and enter the sample tank 28 deeper, making centrifugation more stable and safe; then the centrifugation process is carried out. During centrifugation, since push rod 121 is cylindrical, ball bearing 231 rolls along the side wall of push rod 121, and push rod 121 does not contact the bottom of channel 22, so it does not affect the centrifugation process; after the centrifugation process is completed, the top cover 1 is opened. 2. When the top cover 12 is opened, the push rod 121 moves away from the gap between the two balls 231, and then the first spring 25 returns to its original position, pushing the second push rod 24 and the first push rod 23 to move towards the first channel 22. When the first spring 25 is fully returned to its original position, that is, when the second push rod 24 stops moving, the bottom of the test tube 3 just contacts the arc-shaped protrusion 241. During this process, due to the change in the height of the bottom of the test tube 3, the test tube 3 will be pushed out a certain distance, that is, the test tube 3 will expose more of the sample slot 28, making it easier to take out the test tube 3.

[0031] In one specific embodiment of the present invention, a plurality of first rollers 281 are uniformly arranged on the side wall of the sample tank 28, and the first rollers 281 are rotatably connected to the side wall of the sample tank 28; and the wheel surface of the first rollers 281 is in contact with the outer surface of the side wall of the test tube 3.

[0032] During operation, several No. 1 rollers 281 are evenly arranged on the side wall of the sample tank 28. The No. 1 rollers 281 are rotatably connected to the side wall of the sample tank 28. The wheel surface of the No. 1 rollers 281 is in contact with the outer surface of the side wall of the test tube 3. During the loading and unloading of the test tube 3, the movement of the test tube 3 causes the No. 1 rollers 281 to rotate. This arrangement changes sliding friction into rolling friction, which facilitates the removal of the test tube 3. Furthermore, during the movement of the No. 2 push rod 24, the presence of the No. 1 rollers 281 makes it easier for the test tube 3 to move along the sample tank 28, avoiding the situation where the test tube 3 gets stuck in the sample tank 28. This also prevents the No. 2 push rod 24 from breaking the test tube 3 during the movement due to the test tube 3 getting stuck.

[0033] In one specific embodiment of the present invention, the end of the second push rod 24 near the first channel 22 is rotatably connected to the second roller 242.

[0034] During operation, the end of the second push rod 24 near the first channel 22 is rotatably connected to the second roller 242. Since the second roller 242 is located at the end of the second push rod 24, and the first push rod 23 is connected to the side of the second push rod 24, the first push rod 23 does not affect the rotation of the second roller 242. When the centrifuge is working, the bottom of the test tube 3 is in contact with the surface of the second roller 242. During centrifugation, the test tube 3 inevitably vibrates; this design reduces the contact area between the bottom of the test tube 3 and the second push rod 24. This reduces the mutual vibration between the bottom of test tube 3 and the second push rod 24, preventing the bottom of test tube 3 from breaking due to violent vibration between it and the second push rod 24. Furthermore, the rotation of the second roller 242 causes the bottom of test tube 3 to move relative to the upper surface of the second push rod 24 under the drive of the second roller 242. Compared with the absence of the second roller 242, this setting makes it easier for test tube 3 to move relative to the second push rod 24, thus making it less likely for test tube 3 to get stuck and increasing the operability of the device.

[0035] In one specific embodiment of the present invention, a limiting groove 243 is provided at the bottom of the arc-shaped protrusion 241, a limiting block 244 is embedded in the limiting groove 243, the limiting block 244 is fixed on the second push rod 24, and a second spring 245 is provided at the top of the limiting block 244.

[0036] During operation, the bottom of the arc-shaped protrusion 241 is provided with a limiting groove 243, and a limiting block 244 is embedded in the limiting groove 243. The limiting block 244 is fixed on the second push rod 24, and a second spring 245 is provided on the top of the limiting block 244. When the centrifuge is working, the second spring 245 is in a compressed state. When the centrifugation ends and the top cover 12 is opened, the arc-shaped protrusion 241 moves to the sample slot 28 port, the second spring 245 resets, and the arc-shaped protrusion 241 moves along the limiting block 244. This process causes the arc-shaped protrusion 241 to push the bottom of the test tube 3, so that more of the test tube 3 is exposed in the sample slot 28, making it easier to take out the test tube 3.

[0037] In one specific embodiment of the present invention, the connection between the first push rod 23 and the ball 231 is a conical surface.

[0038] During operation, the connection between the first push rod 23 and the ball 231 is a conical surface. Compared to not having a conical surface, this design makes it easier for the push rod 121 to be inserted between the two balls 231, ensuring the normal operation of the device. Furthermore, the conical surface ensures that during centrifugation, the conical surface will not contact the push rod 121, and only the balls 231 will contact the push rod 121, thus avoiding wear on the device. After centrifugation, when the top cover 12 is opened, the push rod 121 is removed from the gap between the two balls 231, and the first push rod 23 is reset. During reset, due to the conical surface design, the side wall of the first push rod 23 is ensured not to contact the push rod 121, allowing the push rod 121 to be moved out smoothly.

[0039] In one specific embodiment of the present invention, the first roller 281, the second roller 242, and the arc-shaped protrusion 241 are all made of rubber.

[0040] During operation, the first roller 281 is made of rubber, which prevents the test tube 3 from breaking due to collision with the side wall of the sample tank 28 during removal. The second roller 242 and the arc-shaped protrusion 241 are also made of rubber, which prevents the bottom of the test tube 3 from breaking due to collision between the second roller 242 and the arc-shaped protrusion 241 and the bottom of the test tube 3 during the movement of the second push rod 24, thus increasing the safety of the device.

[0041] The specific workflow is as follows:

[0042] The turntable 21 is equipped with multiple sample slots 28, a second channel 26, a first push rod 23, a second push rod 24, and a first spring 25. All sample slots 28, second channels 26, first push rods 23, second push rods 24, and first springs 25 are symmetrical about the central axis of the turntable 21. A centrifugal purification column for DNA extraction is fixedly installed inside a test tube 3, and an appropriate amount of treated plasma is injected into the test tube 3. The test tube 3 is then capped and placed in the sample slot 28. This is the initial state of the device, with the bottom of the test tube 3 resting against the arc-shaped protrusion 241. Then, the top cover 12 is closed. During the process of closing the top cover 12, the push rod 121 moves down in the first channel 22 and then pushes against the gap between the two ball bearings 231. The gap width between 31 is less than the diameter of the push rod 121. The ball bearing 231 rolls, and the first push rod 23 moves away from the first channel 22. Therefore, the first push rod 23 pushes the second push rod 24 to move horizontally away from the first channel 22, and the first spring 25 is compressed. When the top cover 12 is completely closed, the bottom of the test tube 3 is in contact with the top of the second push rod 24 but not with the arc-shaped protrusion 241. Therefore, the test tube 3 will move downward and enter the sample tank 28 more deeply, making the centrifugation more stable and safe. Then the centrifugation process is carried out. During centrifugation, since the push rod 121 is cylindrical, the ball bearing 231 rolls along the side wall of the push rod 121, and the push rod 121 does not contact the bottom of the first channel 22, so it does not affect the centrifugation process. After the centrifugation process is completed, the top cover 12 is opened. When the top cover 12 is opened, the push rod 121 moves away from the gap between the two ball bearings 231, and then the first spring 25 returns to its original position, pushing the second push rod 24 and the first push rod 23 towards the first channel 22. When the first spring 25 is fully returned to its original position, that is, when the second push rod 24 stops moving, the bottom of the test tube 3 just contacts the arc-shaped protrusion 241. During this process, due to the change in the height of the bottom of the test tube 3, the test tube 3 will be pushed out a certain distance, that is, more of the test tube 3 will be exposed in the sample slot 28, making it easier to remove the test tube 3. In addition, several first rollers 281 are evenly arranged on the side wall of the sample slot 28, and the wheel surface of the first roller 281 is in contact with the outer surface of the side wall of the test tube 3. During the loading and unloading of the test tube 3, the movement of the test tube 3 causes the first rollers 281 to rotate. This design transforms sliding friction into rolling friction, facilitating the removal of test tube 3. Furthermore, during the movement of push rod 24, the presence of roller 281 makes it easier for test tube 3 to move along sample groove 28, preventing it from getting stuck and thus avoiding the possibility of push rod 24 breaking the test tube 3 during movement. In addition, roller 242 is located at the end of push rod 24 near channel 22. Since roller 242 is located at the end of push rod 24, and push rod 23 is connected to the side of push rod 24, push rod 23 does not affect the rotation of roller 242. When the centrifuge is operating, the bottom of test tube 3 is in contact with the surface of roller 242.During centrifugation, test tube 3 inevitably vibrates. This design reduces the contact area between the bottom of test tube 3 and push rod 24, thereby reducing mutual vibration between them and preventing the bottom of test tube 3 from breaking due to severe vibration. Furthermore, the rotation of roller 242 allows the bottom of test tube 3 to move relative to the upper surface of push rod 24 under its influence. Compared to the absence of roller 242, this design makes relative movement of test tube 3 on push rod 24 easier, reducing the likelihood of jamming and increasing the operability of the apparatus.

[0043] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0044] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for extracting cell-free DNA, characterized in that: The system includes a power system, a rotation system, and test tubes. The power system comprises a housing, a top cover, and a power box. The power box is fixedly installed at the bottom of the housing, and the top cover is movably connected to the top of the housing via threads. A push rod is located at the center of the bottom of the top cover. The rotation system includes a turntable, a first channel, a first push rod, a second push rod, a first spring, a second channel, a rotating shaft, and a sample slot. A rotating shaft is fixedly installed at the center of the bottom of the turntable, and the turntable is connected to the inside of the power box via the rotating shaft. A first channel is located at the center of the turntable. A second channel is horizontally arranged near the bottom of the turntable. A first push rod is embedded in the end of the second channel near the first channel. A ball bearing is nested at the end of the first push rod near the first channel. The other end of the first push rod is fixedly connected to the side of the second push rod. An arc-shaped protrusion is provided at the top of the second push rod, and the end of the second push rod near the outer wall of the turntable is fixedly connected to the outer wall of the turntable near the outer wall via a first spring. A sample slot is inclinedly arranged near the side wall of the turntable, and the sample slot communicates with the second channel. The sidewall of the sample cell is evenly provided with several No. 1 rollers, which are rotatably connected to the sidewall of the sample cell; and the wheel surface of the No. 1 roller is in contact with the outer surface of the sidewall of the test tube; the No. 1 roller, the No. 2 roller, and the arc-shaped protrusion are all made of rubber. The end of the push rod closest to channel one is rotatably connected to roller number two. The bottom of the arc-shaped protrusion is provided with a limiting groove, a limiting block is embedded in the limiting groove, the limiting block is fixed on the second push rod, and the top of the limiting block is provided with a second spring. When the centrifuge is working, the bottom of the test tube contacts the second roller, reducing the vibration between the bottom of the test tube and the second push rod, thus preventing the bottom of the test tube from breaking. The rotation of the second roller causes the bottom of the test tube to move relative to the upper surface of the second push rod, making it less likely for the test tube to get stuck.

2. The cell-free DNA extraction system according to claim 1, characterized in that: The connection between the first push rod and the ball bearing is a conical surface.

Images