Medical trace sample injector

Abstract

The invention discloses a medical microscale sample injector, and relates to the field of experimental appliances, the medical microscale sample injector comprises a shell, a quantitative sample injection driving assembly, a microscale sample injection driving assembly, a gun head sleeve, a first piston, a first connecting rod and a liquid storage gun head, the interior of the shell is a hollow cavity, and the gun head sleeve is arranged at the bottom of the inner cavity of the shell; the bottom end of the gun head sleeve penetrates through the cavity wall of the shell and then communicates with the liquid storage gun head, the first piston is slidably connected to the interior of the gun head sleeve, one end of the first connecting rod is fixedly connected with the top of the first piston, and the other end of the first connecting rod penetrates through the gun head sleeve and then is in threaded connection with the working end of the micro sample adding driving assembly; the trace sample adding driving assembly and the quantitative sample adding driving assembly are arranged on the top of the inner cavity of the shell side by side, and the gas outlet end of the quantitative sample adding driving assembly is communicated with the gun head sleeve through a pipeline. The continuous liquid injection device is simple in structure and convenient to use, and continuous liquid injection operation of multiple times of quantitative and non-quantitative dropwise adding of a sample solution is achieved.

Description

Technical Field

[0001] The invention relates to the field of experimental instruments, in particular to a medical micro-pipette. Background Art

[0002] Micro-pipette (micro-pipette gun) is a kind of experimental apparatus commonly used in laboratories for transferring a small amount or a small amount of liquid. The mechanical micro-pipette gun commonly used in existing laboratories is to set the maximum range of disposable dripping by twisting the operating rod connected to the piston rod of the piston pusher device in the gun body, and then complete the operation of absorbing liquid and injecting liquid by the operating rod, and the amount of liquid sucked can only be dripped all at once; although this kind of micro-pipette gun can select a single-channel sample adding gun head or a multi-channel row type sample adding gun head as needed, it cannot realize the continuous injection function of repeatedly dripping liquid after one-time liquid absorption, and needs to repeatedly absorb liquid and inject liquid when continuously adding the same equal amount of sample, and the operation is very cumbersome, and greatly wastes time, and some experiments also affect the final result due to the problem of sample addition time difference. In addition, although there are electronic pipette guns that can solve the problem of continuous sample addition on the existing market, the structure of the electronic pipette gun is very complicated, and the purchase, use and maintenance costs are all high, which is not conducive to promotion and application for some smaller laboratories.

[0003] Therefore, how to develop a medical micropipette with a simple structure, easy to use, and capable of achieving multiple quantitative and non-quantitative continuous injection operations of sample solution has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0004] The purpose of the present invention is to provide a medical micro-sampler with simple structure and convenient use, which can realize the continuous injection operation of multiple quantitative and non-quantitative dropwise addition of sample solutions.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a medical micro-injector, comprising a shell, a quantitative injection driving assembly, a micro-injecting driving assembly, a gun head sleeve, a first piston, a first connecting rod and a liquid storage gun head. The interior of the shell is arranged in a hollow cavity, the gun head sleeve is arranged at the bottom of the inner cavity of the shell, and the bottom end of the gun head sleeve penetrates the cavity wall of the shell and is connected to the liquid storage gun head, the first piston is slidably connected to the interior of the gun head sleeve, one end of the first connecting rod is fixedly connected to the top of the first piston, and the other end of the first connecting rod penetrates the gun head sleeve and is threadedly connected to the working end of the micro-injecting driving assembly, the micro-injecting driving assembly and the quantitative injection driving assembly are arranged side by side at the top of the inner cavity of the shell, and the air outlet end of the quantitative injection driving assembly is connected to the gun head sleeve through a pipeline.

[0007] Preferably, a guide strip is provided on one side of the first connecting rod, a guide block slidably matched with the guide strip is provided on the top of the gun head sleeve, and the first connecting rod is configured as a threaded sleeve;

[0008] The micro-injection driving assembly includes a second connecting rod, a rotating dial, a driven gear, a driving gear, a third connecting rod and a rotating handle. The second connecting rod is provided with a threaded end which is threadedly connected to the first connecting rod. When the second connecting rod rotates, it drives the first connecting rod and the first piston to slide up and down in the gun head sleeve. The rotating dial and the driven gear are fixedly connected to the top of the second connecting rod, and the rotating dial is located below the driven gear. The third connecting rod is rotatably connected to the top plate of the shell, and the driving gear arranged at the bottom end of the third connecting rod is meshed with the driven gear. The top end of the third connecting rod passes through the top plate of the shell and is connected to the rotating handle.

[0009] Preferably, the number of teeth of the driving gear is greater than the number of teeth of the driven gear.

[0010] Preferably, one side of the housing is provided with an opening matching the rotating dial.

[0011] Preferably, a limiting ring for limiting the first piston is provided inside the gun head sleeve, and a plurality of first air exchange holes are provided on the top of the gun head sleeve.

[0012] Preferably, the quantitative sampling drive assembly includes a cylinder sleeve, a second piston, a fourth connecting rod, a spring, a first limit block, a first one-way valve, a second one-way valve and a ball valve, the second piston is slidably connected to the inside of the cylinder sleeve, the bottom end of the fourth connecting rod penetrates the housing and the cavity wall of the cylinder sleeve from top to bottom in sequence and is fixedly connected to the second piston, the first limit block is fixedly connected to the fourth connecting rod, the spring is sleeved on the fourth connecting rod, and the two ends of the spring are respectively abutted against the opposite surfaces of the first limit block and the cylinder sleeve, the bottom of the cylinder sleeve is provided with an air outlet and a first air inlet, the air outlet end of the first one-way valve is connected to the first air inlet, the air outlet end of the second one-way valve is connected to the second air inlet provided on the gun head sleeve, and the second one-way valve is located below the limit ring, the air inlet end of the second one-way valve is connected to the air outlet through a pipeline, and the ball valve is provided on one side of the housing and is used to control the opening and closing of the pipeline.

[0013] Preferably, a plurality of second ventilation holes are provided on the top of the cylinder sleeve.

[0014] Preferably, the quantitative sampling drive assembly also includes a press-limit assembly, which includes a guide column, a threaded rod and a limit plate, one end of the guide column is fixedly connected to the top of the cylinder sleeve, the other end of the guide column passes through the guide hole on the limit plate and abuts against the inner cavity wall of the shell, one end of the threaded rod passes through the shell cavity wall from top to bottom and is rotatably connected to the top of the cylinder sleeve, the threaded rod cooperates with the threaded hole on the limit plate, and when the threaded rod rotates, the limit plate is driven to move along the axial direction of the guide column, and the first limit block is positioned by the limit plate when it moves; a limit hole for avoiding air is opened at the center position of the limit plate, and the diameter of the limit hole is larger than the outer diameter of the spring.

[0015] Preferably, a transparent observation window is provided on one side of the housing close to the limiting plate, and a scale line is provided on one side of the transparent observation window;

[0016] A marking line matching the scale line is arranged on one side of the limit plate close to the transparent observation window.

[0017] Compared with the prior art, the beneficial technical effects of the present invention are:

[0018] 1) The setting of the rotating dial facilitates the user to perform multiple operations of dripping a small amount of liquid sample. The user can control the moving distance of the first piston in the gun head sleeve by accurately controlling the number of rotations of the rotating dial, and then use the air pressure to achieve accurate control of the amount of liquid dripped in the liquid storage gun head; at the same time, in order to facilitate the user to control the amount of liquid sample dripped by rotating the dial, the rotating dial is provided with corresponding scale lines, so that the control of the amount of liquid sample dripped can be more precise. The user can adjust the amount of liquid dripped more accurately according to the scale lines, so as to meet the precise requirements of different experiments or operations on the amount of liquid, and improve the accuracy and reliability of the operation;

[0019] 2) The first connecting rod adopts a threaded sleeve design, which can be threadedly fitted with the threaded end of the second connecting rod. This design cleverly solves the problem of a larger device volume caused by using a longer threaded rod to drive the piston to move in the prior art, and further optimizes the overall volume of the device;

[0020] 3) The user can adjust the upper and lower height positions of the limit plate by rotating the threaded rod, and the diameter of the limit hole opened at the center position of the limit plate is smaller than the diameter of the first limit block, so that the limit plate can limit the downward position of the first limit block. In this way, the user presses the fourth connecting rod downward by the same distance each time, thereby realizing multiple quantitative drop operations of the liquid sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below in conjunction with the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the overall structure of a medical micro-pipette of the present invention;

[0023] Figure 2 This is a cross-sectional view of the overall structure of a medical micro-pipette of the present invention;

[0024] Figure 3 This is a schematic diagram of the connection structure of the micro-injection drive assembly, the first connecting rod, the first piston, and the gun head sleeve of the present invention;

[0025] Figure 4 It is a top view of the connection structure of the guide strip and the guide block of the present invention;

[0026] Figure 5 This is a schematic diagram of the structure of the quantitative sample addition drive assembly of the present invention;

[0027] Figure 6 For the present invention Figure 5 The enlarged view of point A in the middle;

[0028] Figure 7 It is a structural schematic diagram of the limiting plate of the present invention.

[0029] Description of reference numerals: 1, housing; 101, transparent observation window;

[0030] 2. Quantitative dosing drive assembly; 201. Cylinder sleeve; 202. Second piston; 203. Fourth connecting rod; 204. Spring; 205. First stop block; 206. First one-way valve; 207. Second one-way valve; 208. Ball valve; 209. Air outlet; 210. Pressing stop assembly; 2101. Guide column; 2102. Threaded rod; 2103. Stop plate; 2104. Guide hole; 2105. Threaded hole; 2106. Stop hole;

[0031] 3. Micro-injection drive assembly; 301. Second connecting rod; 302. Rotating dial; 303. Driven gear; 304. Driving gear; 305. Third connecting rod; 306. Rotating handle;

[0032] 4. Gun head sleeve; 5. First piston; 6. First connecting rod; 7. Liquid storage gun head; 8. Limiting ring; 9. Guide strip; 10. Guide block. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] like Figure 1-7 As shown, a medical micro-injector comprises a shell 1, a quantitative injection driving assembly 2, a micro-injecting driving assembly 3, a gun head sleeve 4, a first piston 5, a first connecting rod 6 and a liquid storage gun head 7. The interior of the shell 1 is arranged in a hollow cavity. The gun head sleeve 4 is arranged at the bottom of the inner cavity of the shell 1, and the bottom end of the gun head sleeve 4 passes through the cavity wall of the shell 1 and is connected to the liquid storage gun head 7. The first piston 5 is slidably connected to the inside of the gun head sleeve 4, one end of the first connecting rod 6 is fixedly connected to the top of the first piston 5, and the other end of the first connecting rod 6 passes through the gun head sleeve 4 and is threadedly connected to the working end of the micro-injecting driving assembly 3. The micro-injecting driving assembly 3 and the quantitative injection driving assembly 2 are arranged side by side at the top of the inner cavity of the shell 1, and the air outlet end of the quantitative injection driving assembly 2 is connected to the gun head sleeve 4 through a pipeline.

[0035] Specifically, the liquid storage gun tip 7 in the present invention is detachably connected to the bottom of the gun tip sleeve 4, so that the user can easily replace a new liquid storage gun tip 7 each time use, which can effectively prevent the residual liquid in the liquid storage gun tip 7 from having an adverse effect on the next use, thereby ensuring the accuracy and reliability of each use and ensuring the smooth progress of experiments or related operations.

[0036] Specifically, a guide bar 9 is provided on one side of the first connecting rod 6, a guide block 10 slidably matched with the guide bar 9 is provided on the top of the gun head sleeve 4, and the first connecting rod 6 is configured as a threaded sleeve;

[0037] The micro-injection driving assembly 3 includes a second connecting rod 301, a rotating dial 302, a driven gear 303, a driving gear 304, a third connecting rod 305 and a rotating handle 306. The second connecting rod 301 is provided with one end with a thread threadedly connected to the first connecting rod 6. When the second connecting rod 301 rotates, it drives the first connecting rod 6 and the first piston 5 to slide up and down in the gun head sleeve 4. The rotating dial 302 and the driven gear 303 are both fixedly connected to the top of the second connecting rod 301, and the rotating dial 302 is located below the driven gear 303. The third connecting rod 305 is rotatably connected to the top plate of the shell 1. The driving gear 304 arranged at the bottom end of the third connecting rod 305 is meshed with the driven gear 303. The top end of the third connecting rod 305 passes through the top plate of the shell 1 and is connected to the rotating handle 306.

[0038] Specifically, the number of teeth of the driving gear 304 is greater than the number of teeth of the driven gear 303 .

[0039] Specifically, one side of the housing 1 is provided with an opening matching the rotating dial 302 .

[0040] Specifically, a limiting ring 8 for limiting the first piston 5 is disposed inside the gun head sleeve 4 , and a plurality of first air exchange holes are opened on the top of the gun head sleeve 4 .

[0041] Specifically, the setting of the rotating dial 302 is convenient for the user to perform multiple operations of dripping a small amount of liquid sample. The user can control the moving distance of the first piston 5 in the gun head sleeve 4 by accurately controlling the number of rotations of the rotating dial 302, and then use the air pressure to achieve accurate control of the amount of liquid dripped in the liquid storage gun head 7; at the same time, in order to facilitate the user to control the amount of liquid sample dripped by rotating the dial 302, corresponding scale lines are provided on the rotating dial 302, so that the control of the amount of liquid sample dripped can be more precise. The user can adjust the amount of liquid dripped more accurately according to the scale lines, so as to meet the precise requirements of different experiments or operations on the amount of liquid, and improve the accuracy and reliability of the operation.

[0042] Specifically, by presetting the transmission ratio coefficient of the driving gear 304 and the driven gear 303, the second connecting rod 301 can be rotated faster at a specific multiple of the speed of the third connecting rod 305. The user can control the number of rotations of the rotating handle 306 to achieve rapid sample dripping, and can cooperate with the rotating dial 302 for fine control; at the same time, the reverse rotation of the rotating handle 306 can also achieve rapid liquid aspiration operation of the liquid storage gun tip 7, which is convenient and practical.

[0043] Specifically, the setting of the limit ring 8 can effectively limit the downward position of the first piston 5, prevent the second connecting rod 301 and the first connecting rod 6 from excessively rotating to cause the threaded connection to separate, and ensure stable operation of the device.

[0044] Specifically, the first connecting rod 6 adopts a threaded sleeve design, which can be threadedly connected to the threaded end of the second connecting rod 301. This design cleverly solves the problem of the larger device volume caused by the use of a longer threaded rod to drive the piston to move in the prior art, and further optimizes the overall volume of the device.

[0045] Specifically, the quantitative addition drive assembly 2 includes a cylinder sleeve 201, a second piston 202, a fourth connecting rod 203, a spring 204, a first limit block 205, a first one-way valve 206, a second one-way valve 207 and a ball valve 208. The second piston 202 is slidably connected to the inside of the cylinder sleeve 201. The bottom end of the fourth connecting rod 203 passes through the housing 1 and the cavity wall of the cylinder sleeve 201 from top to bottom and is fixedly connected to the second piston 202. The first limit block 205 is fixedly connected to the fourth connecting rod 203. The spring 204 is sleeved on the fourth connecting rod 203, and the The two ends of the spring 204 are respectively abutted against the opposite surfaces of the first limit block 205 and the cylinder sleeve 201, and the bottom of the cylinder sleeve 201 is provided with an outlet 209 and a first air inlet, the outlet end of the first one-way valve 206 is connected with the first air inlet, the outlet end of the second one-way valve 207 is connected with the second air inlet provided on the gun head sleeve 4, and the second one-way valve 207 is located below the limit ring 8, the inlet end of the second one-way valve 207 is connected with the outlet 209 through a pipeline, and the ball valve 208 is arranged on one side of the shell 1, and is used to control the opening and closing of the pipeline.

[0046] Specifically, a plurality of second ventilation holes are formed on the top of the cylinder sleeve 201 .

[0047] Specifically, the quantitative sample addition drive assembly 2 also includes a press-limit assembly 210, which includes a guide column 2101, a threaded rod 2102 and a limit plate 2103. One end of the guide column 2101 is fixedly connected to the top of the cylinder sleeve 201, and the other end of the guide column 2101 passes through the guide hole 2104 on the limit plate 2103 and then abuts against the inner cavity wall of the shell 1. One end of the threaded rod 2102 passes through the cavity wall of the shell 1 from top to bottom and then abuts against the inner cavity wall of the shell 1. The top of the cylinder sleeve 201 is rotatably connected, and the threaded rod 2102 cooperates with the threaded hole 2105 on the limit plate 2103. When the threaded rod 2102 rotates, it drives the limit plate 2103 to move along the axial direction of the guide column 2101, and the first limit block 205 is positioned by the limit plate 2103 when moving; a limit hole 2106 for avoiding air is opened at the center position of the limit plate 2103, and the diameter of the limit hole 2106 is larger than the outer diameter of the spring 204.

[0048] Specifically, the setting of the spring 204 and the first limit block 205 can realize the reset operation of the fourth connecting rod 203 and the second piston 202 in the downward position in the cylinder sleeve 201, so that the user can realize the liquid dripping operation by repeatedly pressing the fourth connecting rod 203.

[0049] Specifically, the user can adjust the upper and lower height positions of the limit plate 2103 by rotating the threaded rod 2102, and the aperture of the limit hole 2106 opened at the center position of the limit plate 2103 is smaller than the diameter of the first limit block 205, so that the limit plate 2103 can limit the downward position of the first limit block 205. In this way, the user presses the fourth connecting rod 203 downward by the same distance each time, thereby realizing multiple quantitative drop operations of liquid samples.

[0050] Specifically, the first one-way valve 206 and the second one-way valve 207 cooperate with each other to replenish gas in the cylinder sleeve 201 and prevent backflow; the setting of the ball valve 208 can be used to control the on-off connection between the quantitative addition drive component 2 and the gun head sleeve 4. The user can open the ball valve 208 when multiple quantitative additions of the sample solution are required, and close it when the liquid storage gun head 7 is aspirating liquid, so as to prevent the suction force generated by the first piston 5 moving upward in the gun head sleeve 4 from being affected.

[0051] Specifically, a transparent observation window 101 is provided on one side of the housing 1 close to the limiting plate 2103, and a scale line is provided on one side of the transparent observation window 101;

[0052] A marking line matching the scale line is provided on one side of the limiting plate 2103 close to the transparent observation window 101 .

[0053] Specifically, the arrangement of the scale lines and the transparent observation window 101 facilitates the precise adjustment of the height of the limiting plate 2103 and improves the accuracy of quantitatively adding the sample solution.

[0054] The use process of the present invention is as follows:

[0055] Each time use is performed, the user needs to install a new liquid storage gun tip 7 on the open end at the bottom of the gun tip sleeve 4, and then immerse the liquid aspiration end of the liquid storage gun tip 7 into the sample solution; then, by rotating the rotating handle 306, the third connecting rod 305 and the driving gear 304 arranged at the bottom thereof are driven to rotate together. Since the driven gear 303 is engaged with the driving gear, the second connecting rod 301 is driven to rotate. Driven by the second connecting rod 301, the first connecting rod 6 moves upward, causing the first piston 5 to move upward in the gun tip sleeve 4 and generate suction. At this time, the ball valve 208 is in the initial closed state, thereby completing the sample solution storage operation of the liquid storage gun tip 7.

[0056] 1) Add sample solution in small amounts multiple times:

[0057] First, the user rotates the rotating dial 302 to achieve a small-angle rotation operation of the second connecting rod 301, and then uses the first connecting rod 6 threadedly connected to the second connecting rod 301 to drive the first piston 5 to move a micro distance, and uses gas pressure to achieve micro-dropping of the sample solution; when performing a large volume of sample solution droplet addition operation, the user can first control the first piston 5 to move downward quickly by rotating the rotating handle 306 in the opposite direction, and then fine-tune the sample solution droplet amount by rotating the rotating dial 302, thereby achieving micro-multiple droplet addition operations of the sample solution.

[0058] 2) Add sample solution quantitatively multiple times:

[0059] First, the user needs to adjust the vertical height of the limit plate 2103 by rotating the threaded rod 2102 according to the scale line set on one side of the transparent observation window 101, so as to accurately limit the downward movement position of the fourth connecting rod 203 and the second piston 202 set at the bottom thereof in the cylinder sleeve 201 through the first limit block 205;

[0060] Then, open the ball valve 208, press down the fourth connecting rod 203, drive the second piston 202 to slide in the cylinder sleeve 201, and release the fourth connecting rod 203 when the first limit block 205 contacts the limit plate 2103. The fourth connecting rod 203 will drive the second piston 202 to move up to the initial position under the rebound force of the spring 204, so that the user can press down the fourth connecting rod 203 again to quantitatively add the sample solution.

[0061] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0062] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A medical micropipette, characterized in that: The invention comprises a shell (1), a quantitative sample addition drive assembly (2), a micro-sample addition drive assembly (3), a gun head sleeve (4), a first piston (5), a first connecting rod (6) and a liquid storage gun head (7); the interior of the shell (1) is arranged in a hollow cavity; the gun head sleeve (4) is arranged at the bottom of the inner cavity of the shell (1); the bottom end of the gun head sleeve (4) passes through the cavity wall of the shell (1) and is connected to the liquid storage gun head (7); the first piston (5) is slidably connected to the interior of the gun head sleeve (4); one end of the first connecting rod (6) is fixedly connected to the top of the first piston (5); the other end of the first connecting rod (6) passes through the gun head sleeve (4) and is threadedly connected to the working end of the micro-sample addition drive assembly (3); the micro-sample addition drive assembly (3) and the quantitative sample addition drive assembly (2) are arranged side by side at the top of the inner cavity of the shell (1); the air outlet end of the quantitative sample addition drive assembly (2) is connected to the gun head sleeve (4) through a pipeline.

2. A medical micropipette according to claim 1, characterized in that: A guide strip (9) is provided on one side of the first connecting rod (6), a guide block (10) which is slidably matched with the guide strip (9) is provided on the top of the gun head sleeve (4), and the first connecting rod (6) is configured as a threaded sleeve; The micro-injection driving assembly (3) comprises a second connecting rod (301), a rotating dial (302), a driven gear (303), a driving gear (304), a third connecting rod (305) and a rotating handle (306). The second connecting rod (301) is provided with a threaded end which is threadedly connected to the first connecting rod (6). When the second connecting rod (301) rotates, the first connecting rod (6) and the first piston (5) are driven to slide up and down in the gun head sleeve (4). The rotating dial (302), the driven gear (303), the driving gear (304), the third connecting rod (305) and the rotating handle (306) are driven to rotate. The driven gear (303) is fixedly connected to the top of the second connecting rod (301), and the rotating dial (302) is located below the driven gear (303). The third connecting rod (305) is rotatably connected to the top plate of the shell (1), and the driving gear (304) arranged at the bottom end of the third connecting rod (305) is meshed with the driven gear (303). The top end of the third connecting rod (305) passes through the top plate of the shell (1) and is connected to the rotating handle (306).

3. A medical micropipette according to claim 2, characterized in that: The number of teeth of the driving gear (304) is greater than the number of teeth of the driven gear (303).

4. A medical micropipette according to claim 2, characterized in that: One side of the housing (1) is provided with an opening matching the rotating dial (302).

5. A medical micropipette according to claim 1, characterized in that: A limiting ring (8) for limiting the position of the first piston (5) is arranged inside the gun head sleeve (4), and a plurality of first air exchange holes are opened on the top of the gun head sleeve (4).

6. A medical micropipette according to claim 5, characterized in that: The quantitative sample addition drive assembly (2) comprises a cylinder sleeve (201), a second piston (202), a fourth connecting rod (203), a spring (204), a first limit block (205), a first one-way valve (206), a second one-way valve (207) and a ball valve (208); the second piston (202) is slidably connected to the interior of the cylinder sleeve (201); the bottom end of the fourth connecting rod (203) penetrates the housing (1) and the cavity wall of the cylinder sleeve (201) from top to bottom in sequence and is fixedly connected to the second piston (202); the first limit block (205) is fixedly connected to the fourth connecting rod (203); and the spring (204) is sleeved on the fourth connecting rod (203). , and the two ends of the spring (204) are respectively in contact with the first limit block (205) and the opposite surface of the cylinder sleeve (201), the bottom of the cylinder sleeve (201) is provided with an outlet (209) and a first air inlet, the outlet end of the first one-way valve (206) is connected to the first air inlet, the outlet end of the second one-way valve (207) is connected to the second air inlet provided on the gun head sleeve (4), and the second one-way valve (207) is located below the limit ring (8), the air inlet end of the second one-way valve (207) is connected to the outlet (209) through a pipeline, and the ball valve (208) is arranged on one side of the shell (1) and is used to control the opening and closing of the pipeline.

7. A medical micropipette according to claim 6, characterized in that: A plurality of second air exchange holes are provided on the top of the cylinder sleeve (201).

8. A medical micropipette according to claim 6, characterized in that: The quantitative sample addition drive assembly (2) further comprises a pressing and limiting assembly (210), wherein the pressing and limiting assembly (210) comprises a guide column (2101), a threaded rod (2102) and a limiting plate (2103), wherein one end of the guide column (2101) is fixedly connected to the top of the cylinder sleeve (201), the other end of the guide column (2101) passes through a guide hole (2104) on the limiting plate (2103) and then abuts against the inner cavity wall of the shell (1), and one end of the threaded rod (2102) passes through the cavity wall of the shell (1) from top to bottom and then abuts against the inner cavity wall of the shell (1). The top of the cylinder sleeve (201) is rotatably connected, the threaded rod (2102) cooperates with the threaded hole (2105) on the limit plate (2103), and when the threaded rod (2102) rotates, it drives the limit plate (2103) to move along the axial direction of the guide column (2101), and when the first limit block (205) moves, it is positioned by the limit plate (2103); a limit hole (2106) for avoiding air is opened at the center position of the limit plate (2103), and the diameter of the limit hole (2106) is larger than the outer diameter of the spring (204).

9. A medical micropipette according to claim 8, characterized in that: A transparent observation window (101) is provided on one side of the housing (1) close to the limiting plate (2103), and a scale line is provided on one side of the transparent observation window (101); A marking line matching the scale line is provided on one side of the limiting plate (2103) close to the transparent observation window (101).

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