A pipette

Abstract

The present invention discloses a pipette. The pipette includes a pipette cavity, which is provided with a first pipette cavity and a second pipette cavity inside. The first pipette cavity and the second pipette cavity are connected, and the cross-sectional area of ​​the first pipette cavity is smaller than the cross-sectional area of ​​the second pipette cavity; a variable-section piston assembly is sequentially arranged to pass through the second pipette cavity and the first pipette cavity; wherein, when the moving end of the variable-section piston assembly moves in the first pipette cavity, the variable-section piston assembly has a moving end adapted to the cross-section of the first pipette cavity, and when the moving end of the variable-section piston assembly moves in the second pipette cavity, the variable-section piston assembly has a moving end adapted to the cross-section of the second pipette cavity. The pipette provided by the present invention can take into account both small-volume pipetting accuracy and large-volume pipetting efficiency, has high versatility, and is suitable for popularization and use.

Description

Technical Field

[0001] The present invention relates to the technical field of pipettes, in particular to a pipette. Background Art

[0002] Pipettes typically use the air displacement principle to aspirate liquid. Through piston movement, an air displacement zone is formed within the pipette chamber, achieving the purpose of aspiration. When pipetting small volumes, to ensure pipetting accuracy, the piston is made thinner, thus ensuring that the volume change of the air displacement zone is smaller with the same stroke, making it easier to control precision. When pipetting large volumes, the piston is made thicker, ensuring that the volume of the air displacement zone is larger with the same stroke.

[0003] Existing small-volume pipettes require a long stroke when performing large-volume pipetting, which takes a long time, occupies a large space and time, and reduces the efficiency of large-volume pipetting; existing large-volume pipettes have low pipetting accuracy when performing small-volume pipetting.

[0004] Therefore, how to balance small-volume pipetting accuracy and large-volume pipetting efficiency is a technical problem that those skilled in the art currently need to solve. Summary of the Invention

[0005] In view of this, an object of the present invention is to provide a pipette that can achieve both small-volume pipetting accuracy and large-volume pipetting efficiency.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A pipette comprising:

[0008] A pipetting cavity, wherein a first pipetting cavity and a second pipetting cavity are provided therein, wherein the first pipetting cavity and the second pipetting cavity are connected, and the cross-sectional area of ​​the first pipetting cavity is smaller than the cross-sectional area of ​​the second pipetting cavity;

[0009] A variable-section piston assembly is sequentially disposed through the second pipetting cavity and the first pipetting cavity;

[0010] In which, when the moving end of the variable-section piston assembly moves in the first pipetting chamber, the variable-section piston assembly has a moving end that is adapted to the cross-section of the first pipetting chamber; when the moving end of the variable-section piston assembly moves in the second pipetting chamber, the variable-section piston assembly has a moving end that is adapted to the cross-section of the second pipetting chamber.

[0011] Optionally, in the above-mentioned pipette, the variable-section piston assembly includes:

[0012] A piston body, wherein a first position-limiting contact portion is provided on the piston body;

[0013] a liquid volume regulating block, slidably disposed in the second pipetting cavity, the liquid volume regulating block being provided with a penetrating cavity and a second limiting contact portion, the movable end of the piston body being sequentially penetrating the penetrating cavity and the first pipetting cavity;

[0014] When the movable end of the piston body is in a disengaged state from the first pipetting cavity, the second position-limiting contact portion contacts the end surface of the first position-limiting contact portion away from the first pipetting cavity.

[0015] Optionally, in the above-mentioned pipette, the outer wall of the piston body extends vertically toward a side away from the piston body to form a limiting boss, and an end surface of the limiting boss away from the first pipetting cavity forms the first limiting contact portion;

[0016] The inner wall of the through cavity is recessed toward the side away from the axis of the piston body to form an annular cavity. The inner wall of the annular cavity away from the first pipetting cavity constitutes the second limiting contact portion. The first limiting contact portion and the second limiting contact portion can contact each other.

[0017] Optionally, in the above-mentioned pipette, the number of the piston body and the number of the liquid volume adjustment block are both one, and sealing rings are provided between the piston body and the liquid volume adjustment block, and between the liquid volume adjustment block and the second pipetting chamber.

[0018] Optionally, in the above-mentioned pipette, the number of the piston bodies is at least two, the number of the liquid volume adjustment blocks is one, and at least two through-cavities are provided on the liquid volume adjustment block, the number of the first pipetting cavities is at least two, and the movable end of each of the piston bodies can pass through the corresponding through-cavity and the first pipetting cavity in sequence.

[0019] Optionally, in the above-mentioned pipette, the number of the piston bodies is one, the number of the liquid volume adjusting blocks is at least two, and the multiple liquid volume adjusting blocks are sequentially socketed from the inside to the outside, and the liquid volume adjusting block located in the outer layer is provided with a sliding pipetting cavity that enables the liquid volume adjusting block located in the inner layer to slide, and the sliding pipetting cavity is provided with a limiting protrusion for limiting the liquid volume adjusting block located in the inner layer.

[0020] Optionally, in the above-mentioned pipette, sealing rings are provided between the piston body and its corresponding through cavity, between adjacent liquid volume adjustment blocks, and between the liquid volume adjustment block and the second pipetting cavity.

[0021] Optionally, in the above-mentioned pipette, the variable-section piston assembly includes:

[0022] Piston body;

[0023] The liquid volume regulating block is arranged at the movable end of the piston body and is made of elastic material. When the movable end of the piston body is located in the first pipetting cavity, the liquid volume regulating block is in a compressed state.

[0024] Optionally, in the above-mentioned pipette, there are multiple second pipetting chambers, and the cross-sectional areas of the multiple second pipetting chambers increase sequentially from the first pipetting chamber toward the second pipetting chambers.

[0025] Optionally, the above-mentioned pipette further includes a driving member for driving the variable-section piston assembly to move.

[0026] When using the pipette provided by the present invention, since the variable-section piston assembly is sequentially arranged through the second pipetting chamber and the first pipetting chamber, when the moving end of the variable-section piston assembly moves in the first pipetting chamber, the variable-section piston assembly has a moving end adapted to the cross-section of the first pipetting chamber, and when the moving end of the variable-section piston assembly moves in the second pipetting chamber, the variable-section piston assembly has a moving end adapted to the cross-section of the second pipetting chamber. Therefore, when the variable-section piston assembly is pulled in the direction from the first pipetting chamber to the second pipetting chamber, the moving end of the variable-section piston assembly first moves in the first pipetting chamber. At this time, the variable-section piston assembly has a moving end adapted to the cross-section of the first pipetting chamber. Since the cross-sectional area of ​​the first pipetting chamber is smaller than the cross-sectional area of ​​the second pipetting chamber, the variable-section piston When the moving end of the component moves in the first pipetting chamber, it can form a small-volume air replacement zone, which is suitable for small-volume pipetting and has high pipetting accuracy; as the variable-section piston assembly continues to move toward the second pipetting chamber, the moving end of the variable-section piston assembly disengages from the first pipetting chamber and enters the second pipetting chamber. Since the cross-sectional area of ​​the first pipetting chamber is smaller than the cross-sectional area of ​​the second pipetting chamber, and when the moving end of the variable-section piston assembly moves in the second pipetting chamber, the variable-section piston assembly has a moving end that is adapted to the cross-section of the second pipetting chamber. Therefore, when the moving end of the variable-section piston assembly moves in the second pipetting chamber, it can form a larger-volume air replacement zone, which is suitable for large-volume pipetting, reduces the stroke and time consumed during large-volume pipetting, and improves the efficiency of large-volume pipetting.

[0027] It can be seen that the pipette provided by the present invention can take into account both small-volume pipetting accuracy and large-volume pipetting efficiency, has high versatility, and is suitable for promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 A schematic structural diagram of a pipette provided by an embodiment of the present invention;

[0030] Figure 2 A schematic structural diagram of a variable-section piston assembly provided by an embodiment of the present invention, in which a movable end leaves a first pipetting chamber and enters a second pipetting chamber;

[0031] Figure 3 A schematic structural diagram of a movable end of a variable-section piston assembly provided by an embodiment of the present invention moving in a second pipetting chamber;

[0032] Figure 4 A schematic structural diagram of a pipette with multiple piston bodies provided in an embodiment of the present invention;

[0033] Figure 5 A schematic structural diagram of another pipette with multiple piston bodies provided by an embodiment of the present invention;

[0034] Figure 6 A schematic structural diagram of a pipette with multiple liquid volume adjustment blocks provided by an embodiment of the present invention;

[0035] Figure 7 A schematic structural diagram of another pipette provided by an embodiment of the present invention;

[0036] Figure 8 A schematic structural diagram of another variable-section piston assembly provided by an embodiment of the present invention, in which the moving end leaves the first pipetting chamber and enters the second pipetting chamber.

[0037] Among them, 100 is the pipetting cavity, 101 is the first pipetting cavity, 102 is the second pipetting cavity, 200 is the variable-section piston assembly, 201 is the piston body, 2011 is the first limiting contact part, 202 is the liquid volume adjustment block, 2021 is the through cavity, 2022 is the annular cavity, 2022-a is the second limiting contact part, 2023 is the limiting protrusion, and 300 is the sealing ring. DETAILED DESCRIPTION

[0038] In view of this, the core of the present invention is to provide a pipette that takes into account both small-volume pipetting accuracy and large-volume pipetting efficiency.

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] like Figures 1 to 8 As shown, an embodiment of the present invention discloses a pipette, including a pipetting chamber 100 and a variable-section piston assembly 200 .

[0041] Among them, a first pipetting chamber 101 and a second pipetting chamber 102 are provided inside the pipetting chamber 100, the first pipetting chamber 101 and the second pipetting chamber 102 are connected, and the cross-sectional area of ​​the first pipetting chamber 101 is smaller than the cross-sectional area of ​​the second pipetting chamber 102; the variable-section piston assembly 200 is sequentially arranged in the second pipetting chamber 102 and the first pipetting chamber 101; when the moving end of the variable-section piston assembly 200 moves in the first pipetting chamber 101, the variable-section piston assembly 200 has a moving end that is adapted to the cross-section of the first pipetting chamber 101, and when the moving end of the variable-section piston assembly 200 moves in the second pipetting chamber 102, the variable-section piston assembly 200 has a moving end that is adapted to the cross-section of the second pipetting chamber 102.

[0042] When using the pipette provided by the present invention, since the variable-section piston assembly 200 is sequentially arranged through the second pipetting chamber 102 and the first pipetting chamber 101, when the moving end of the variable-section piston assembly 200 moves in the first pipetting chamber 101, the variable-section piston assembly 200 has a moving end adapted to the cross-section of the first pipetting chamber 101, and when the moving end of the variable-section piston assembly 200 moves in the second pipetting chamber 102, the variable-section piston assembly 200 has a moving end adapted to the cross-section of the second pipetting chamber 102. Therefore, when the variable-section piston assembly 200 is pulled in the direction from the first pipetting chamber 101 to the second pipetting chamber 102, the moving end of the variable-section piston assembly 200 first moves in the first pipetting chamber 101. At this time, the variable-section piston assembly 200 has a moving end adapted to the cross-section of the first pipetting chamber 101. Since the cross-sectional area of ​​the first pipetting chamber 101 is smaller than the cross-sectional area of ​​the second pipetting chamber 102 102, so the moving end of the variable-section piston assembly 200 can form a small-volume air replacement zone when it moves in the first pipetting chamber 101, which is suitable for small-volume pipetting and has high pipetting accuracy; as the variable-section piston assembly 200 continues to move toward the second pipetting chamber 102, the moving end of the variable-section piston assembly 200 disengages from the first pipetting chamber 101 and enters the second pipetting chamber 102. Since the cross-sectional area of ​​the first pipetting chamber 101 is smaller than the cross-sectional area of ​​the second pipetting chamber 102, and the moving end of the variable-section piston assembly 200 moves in the second pipetting chamber 102, the variable-section piston assembly 200 has a moving end that is adapted to the cross-section of the second pipetting chamber 102. Therefore, when the moving end of the variable-section piston assembly 200 moves in the second pipetting chamber 102, a larger-volume air replacement zone can be formed, which is suitable for large-volume pipetting, reduces the stroke and time consumed during large-volume pipetting, and improves the efficiency of large-volume pipetting.

[0043] It can be seen that the pipette provided by the present invention can take into account both small-volume pipetting accuracy and large-volume pipetting efficiency, has high versatility, and is suitable for promotion and use.

[0044] It should be understood that the moving end of the variable-section piston assembly 200 can be a rigid part or an elastic material that can undergo elastic deformation. As long as the part type can meet the use requirements, it falls within the scope of protection of the present invention.

[0045] Optionally, in a specific embodiment of the present invention, the variable-section piston assembly 200 includes a piston body 201 and a liquid volume adjustment block 202, so that the volume of the air replacement zone can be adjusted through the liquid volume adjustment block 202, thereby adjusting the pipetting volume.

[0046] Specifically, if Figures 1 to 3 As shown, the piston body 201 is provided with a first limiting contact portion 2011; the liquid volume regulating block 202 has an outer wall adapted to the second pipetting chamber 102, and the liquid volume regulating block 202 is slidably arranged in the second pipetting chamber 102, and the liquid volume regulating block 202 is provided with a through cavity 2021 and a second limiting contact portion 2022-a. The movable end of the piston body 201 sequentially penetrates the through cavity 2021 and the first pipetting chamber 101, so that when the piston body 201 is pulled in the direction from the first pipetting chamber 101 to the second pipetting chamber 102, the movable end of the piston body 201 first moves in the first pipetting chamber 101, forming a small volume of air replacement area, which is suitable for small volume pipetting and has high pipetting accuracy. After being separated from the first pipetting chamber 101, it moves in the through cavity 2021 again; and when the movable end of the piston body 201 is in a disengaged state from the first pipetting chamber 101, the second limiting contact portion 2022- a contacts the end face of the first limiting contact part 2011 away from the first pipetting chamber 101, so that after the piston body 201 is separated from the first pipetting chamber 101, when the piston body 201 continues to be pulled along the direction of the first pipetting chamber 101 toward the second pipetting chamber 102, the piston body 201 drives the liquid volume adjustment block 202 to slide in the second pipetting chamber 102 through the contact between its first limiting contact part 2011 and the second limiting contact part 2022-a of the liquid volume adjustment block 202. At this time, the moving end of the variable-section piston assembly 200 is a large-section end formed by the combination of the end of the piston body 201 and the end of the liquid volume adjustment block 202. The cross-sectional area of ​​the air replacement zone formed is larger than that of the air replacement zone formed in the first pipetting chamber 101. For the same stroke, the liquid volume is increased, which is suitable for large-volume pipetting, reduces the stroke and time consumed during large-volume pipetting, and improves the efficiency of large-volume pipetting.

[0047] It should be understood that the above-mentioned first limit contact part 2011 and the second limit contact part 2022-a can both be parts of the type of bosses, shoulders or limit blocks, and as long as the structural type can meet the use requirements, it falls within the protection scope of the present invention; optionally, an embodiment of the present invention provides a specific structure of the first limit contact part 2011 and the second limit contact part 2022-a.

[0048] Specifically, the outer wall of the piston body 201 extends vertically toward the side away from the piston body 201 to form a limiting boss, and the limiting boss forms a first limiting contact portion 2011 away from the end face of the first pipetting chamber 101; the inner wall of the through-cavity 2021 is recessed toward the side away from the axis of the piston body 201 to form an annular cavity 2022, and the annular cavity 2022 forms a second limiting contact portion 2022-a away from the inner wall of the first pipetting chamber 101. The first limiting contact portion 2011 and The second limiting contact portion 2022-a is able to contact and cooperate with the first limiting contact portion 2011 and the second limiting contact portion 2022-a, so that after the moving end of the piston body 201 is separated from the first pipetting chamber 101 and enters the through cavity 2021 of the liquid volume adjustment block 202, the liquid volume adjustment block 202 can move together with the piston body 201 in the pipetting chamber 100 toward the side away from the first pipetting chamber 101, thereby realizing the switching from small volume pipetting to large volume pipetting.

[0049] In addition, the present invention does not specifically limit the number of the above-mentioned piston bodies 201 and liquid volume adjustment blocks 202. In actual applications, the number of piston bodies 201 and liquid volume adjustment blocks 202 can be adaptively adjusted according to actual needs. As long as the number can meet the use requirements, it falls within the protection scope of the present invention.

[0050] like Figures 1 to 3 As shown, in a specific embodiment of the present invention, the number of the piston body 201 and the liquid volume adjustment block 202 is one, and a sealing ring 300 is provided between the piston body 201 and the liquid volume adjustment block 202, and between the liquid volume adjustment block 202 and the second pipetting chamber 102, so as to improve the sealing of the pipette and facilitate the extraction of liquid.

[0051] like Figure 4 and Figure 5As shown, in another specific embodiment of the present invention, the number of piston bodies 201 is at least two, the number of liquid volume adjustment blocks 202 is one, and at least two through-cavities 2021 are provided on the liquid volume adjustment block 202, and the number of first pipetting cavities 101 is at least two, so that the moving end of each piston body 201 can pass through the through-cavity 2021 and the first pipetting cavity 101 corresponding thereto in turn, realizing the parallel connection of at least two piston bodies 201, and each piston body 201 can move independently to realize a step-by-step increase in the cross-sectional area of ​​the air replacement zone, so as to meet the needs of step-by-step liquid volume adjustment and further expand the application range of the pipette.

[0052] It should be understood that the plurality of through cavities 2021 can be arranged in parallel or radially. In practical applications, the through cavities 2021 can be adaptively adjusted according to specific pipetting requirements. As long as the arrangement can meet the use requirements, it falls within the scope of protection of the present invention. Figure 4 The figure shows a specific embodiment in which multiple through cavities 2021 are arranged in parallel. Accordingly, the movement trajectories of the multiple piston bodies 201 are parallel. Figure 5 The figure shows a specific embodiment in which multiple through-cavities 2021 radiate in a direction away from the radiation center with a preset position as the radiation center. The shape radiated by the multiple through-cavities 2021 can be circular, semicircular or fan-shaped, etc., and the present invention does not make specific limitations. In addition, the angle between the radiation directions of adjacent through-cavities 2021 is not specifically limited. As long as the setting method can meet the use requirements, it falls within the protection scope of the present invention.

[0053] like Figure 6 As shown, there is one piston body 201 and at least two liquid volume adjusting blocks 202. The multiple liquid volume adjusting blocks 202 are sequentially connected from the inside to the outside, and the liquid volume adjusting block 202 located in the outer layer is provided with a sliding pipetting cavity 100 that enables the liquid volume adjusting block 202 located in the inner layer to slide. The sliding pipetting cavity 100 is provided with a limiting protrusion 2023 for limiting the liquid volume adjusting block 202 located in the inner layer, so that after the piston body 201 is separated from the first pipetting cavity 101 and continues to move along the first pipetting cavity 101 toward the second pipetting cavity 102, the piston body 201 drives each liquid volume adjusting block 202 to move away from the first pipetting cavity 101 in sequence from the inner layer to the outer layer, thereby realizing a step-by-step increase in the cross-sectional area of ​​the air replacement zone, facilitating step-by-step liquid volume control, and further expanding the application range of the pipette.

[0054] It should be understood that in the above Figures 4 to 6In the specific embodiment shown, sealing rings 300 are provided between the piston body 201 and its corresponding through cavity 2021, between adjacent liquid volume adjustment blocks 202, and between the liquid volume adjustment block 202 and the second pipetting cavity 102 to meet the sealing requirements of the pipette and facilitate pipetting.

[0055] like Figure 7 As shown, in another specific embodiment of the present invention, the variable cross-section piston assembly 200 includes a piston body 201 and a liquid volume regulating block 202; wherein, the liquid volume regulating block 202 is arranged at the moving end of the piston body 201, and the liquid volume regulating block 202 is made of elastic material. When the moving end of the piston body 201 is located in the first pipetting chamber 101, the liquid volume regulating block 202 is in a compressed state, so that the liquid volume regulating block 202 is in a compressed state in the first pipetting chamber 101, and a small volume of air replacement area can be formed when moving, which is suitable for small volume pipetting and has high pipetting accuracy; when the liquid volume regulating block 202 moves with the piston body 201 to the second pipetting chamber After moving to the second pipetting chamber 102, based on the performance of the elastic material that can restore to its original shape and the characteristic that the cross-sectional area of ​​the second pipetting chamber 102 is larger than the cross-sectional area of ​​the first pipetting chamber 101, the liquid volume adjustment block 202 restores to its original shape or its elastic deformation becomes smaller than the elastic deformation in the first pipetting chamber 101 after moving to the second pipetting chamber 102, so as to adapt to the internal volume of the second pipetting chamber 102. When the piston body 201 drives the liquid volume adjustment block 202 to move in the second pipetting chamber 102, a larger air replacement area can be formed, thereby realizing the switching from small-volume pipetting to large-volume pipetting, reducing the stroke and time consumed during large-volume pipetting, and improving the efficiency of large-volume pipetting.

[0056] It should be noted that the elastic material used in the liquid volume regulating block 202 may be TPU, TPE, silicone, butyl rubber and other types of materials. As long as the material type can meet the use requirements, it falls within the protection scope of the present invention.

[0057] Furthermore, in the above-mentioned embodiment in which the liquid volume adjustment block 202 is made of elastic material, there is no specific restriction on the number of the second pipetting chambers 102, and as long as the number can meet the use requirements, it falls within the protection scope of the present invention; in addition, the cross-sectional areas of the multiple second pipetting chambers 102 can be the same or different, and as long as the cross-sectional area can meet the use requirements, it falls within the protection scope of the present invention.

[0058] Optionally, in a specific embodiment of the present invention, there are multiple second pipetting chambers 102, and the cross-sectional areas of the multiple second pipetting chambers 102 increase successively from the first pipetting chamber 101 toward the second pipetting chambers 102, so that in the subsequent stroke after the liquid volume adjustment block 202 is separated from the first pipetting chamber 101, the cross-sectional areas increase successively along the direction from the first pipetting chamber 101 toward the second pipetting chamber 102, and the volume of the air replacement zone formed increases successively, thereby realizing step-by-step adjustment of the liquid volume of the pipette, further enriching the function of the pipetting, and expanding the scope of application.

[0059] The pipette provided by the present invention further includes a driving member, which drives the variable-section piston assembly 200 to move inside the movable cavity 100 .

[0060] The above-mentioned driving component can be a motor, hydraulic cylinder or pneumatic cylinder type driving component. As long as the driving component can meet the use requirements, it belongs to the protection scope of the present invention; optionally, in a specific embodiment of the present invention, the driving component is a motor.

[0061] The terms "first," "second," and the like in the specification, claims, and accompanying drawings of the present invention are used to distinguish between different items, not to describe a specific order. Furthermore, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements and may include steps or elements that are not listed.

[0062] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pipette, characterized in that include: A pipetting cavity, wherein a first pipetting cavity and a second pipetting cavity are provided therein, wherein the first pipetting cavity and the second pipetting cavity are connected, and the cross-sectional area of ​​the first pipetting cavity is smaller than the cross-sectional area of ​​the second pipetting cavity; A variable-section piston assembly is sequentially disposed through the second pipetting cavity and the first pipetting cavity; Wherein, when the moving end of the variable-section piston assembly moves in the first pipetting cavity, the variable-section piston assembly has a moving end adapted to the cross-section of the first pipetting cavity; when the moving end of the variable-section piston assembly moves in the second pipetting cavity, the variable-section piston assembly has a moving end adapted to the cross-section of the second pipetting cavity; The variable-section piston assembly comprises: a piston body, the piston body being provided with a first position-limiting contact portion; a liquid volume adjustment block being slidably disposed in the second pipetting cavity, the liquid volume adjustment block being provided with a through-cavity body and a second position-limiting contact portion, and the movable end of the piston body sequentially passes through the through-cavity body and the first pipetting cavity; wherein, when the movable end of the piston body is disengaged from the first pipetting cavity, the second position-limiting contact portion contacts the end face of the first position-limiting contact portion away from the first pipetting cavity; The outer wall of the piston body extends vertically toward the side away from the piston body to form a limiting boss, and the limiting boss forms the first limiting contact portion away from the end face of the first pipetting cavity; the inner wall of the through-cavity is recessed toward the side away from the axis of the piston body to form an annular cavity, and the inner wall of the annular cavity away from the first pipetting cavity constitutes the second limiting contact portion, and the first limiting contact portion and the second limiting contact portion can contact each other.

2. The pipette according to claim 1, characterized in that The number of the piston body and the number of the liquid volume regulating block are both one, and sealing rings are provided between the piston body and the liquid volume regulating block, and between the liquid volume regulating block and the second pipetting cavity.

3. The pipette according to claim 1, characterized in that The number of the piston bodies is at least two, the number of the liquid volume adjustment blocks is one, and the liquid volume adjustment block is provided with at least two through-cavities, the number of the first pipetting cavities is at least two, and the movable end of each of the piston bodies can pass through the corresponding through-cavity and the first pipetting cavity in sequence.

4. The pipette according to claim 1, characterized in that The number of the piston bodies is one, and the number of the liquid volume adjusting blocks is at least two. The multiple liquid volume adjusting blocks are sequentially connected from the inside to the outside, and the liquid volume adjusting block located on the outer layer is provided with a sliding pipetting cavity that enables the liquid volume adjusting block located on the inner layer to slide, and the sliding pipetting cavity is provided with a limiting protrusion for limiting the liquid volume adjusting block located on the inner layer.

5. The pipette according to claim 3 or 4, characterized in that Sealing rings are provided between the piston body and its corresponding through cavity, between adjacent liquid volume adjustment blocks, and between the liquid volume adjustment block and the second pipetting cavity.

6. The pipette according to claim 1, characterized in that The variable-section piston assembly comprises: Piston body; The liquid volume regulating block is arranged at the movable end of the piston body and is made of elastic material. When the movable end of the piston body is located in the first pipetting cavity, the liquid volume regulating block is in a compressed state.

7. The pipette according to claim 6, characterized in that There are multiple second pipetting cavities, and the cross-sectional areas of the multiple second pipetting cavities increase sequentially from the first pipetting cavity toward the second pipetting cavities.

8. The pipette according to claim 1, wherein It also includes a driving member for driving the variable-section piston assembly to move.

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