A pipetting device for cell culture

Abstract

The application discloses a pipetting device for cell culture and relates to the technical field of cell culture experiment equipment, which comprises a shell, a piston mechanism installed in the shell, a back suction mechanism sleeved at the lower part of the shell and a cone head connected to the lower end of the shell. The inner cavity of the cone head is detachably connected with a disposable diaphragm assembly. The disposable diaphragm assembly comprises a coaxially connected upper base segment and lower base segment. The inner cavity top of the upper base segment is provided with a second cavity. The inner wall middle part of the upper base segment is provided with a second step. The first diaphragm and the second diaphragm are fixedly connected to the second step. The two layers of diaphragms form a closed indicating cavity. Through the cooperation of the cone head and the disposable diaphragm assembly, the problems of the conventional air replacement type pipetting device, such as the cross contamination of aerosol caused by the lack of physical separation between gas and liquid, the sharp decrease and failure of the protection performance of the filter core barrier structure after soaking, the large influence of the material tolerance on the precision of the diaphragm type pipetting structure, and the difficulty in balancing the sealing reliability and the plugging feel are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of cell culture experimental equipment technology, specifically a pipetting device for cell culture. Background Technology

[0002] As the core experimental equipment for cell culture liquid transfer and precise reagent dispensing, the pipetting device is a key unit that determines the uniformity of cell seeding, the accuracy of reagent addition, the effectiveness of sample contamination control, and the overall efficiency of experimental operations.

[0003] Existing pipetting devices for cell culture mostly employ three technical approaches: air-displacement direct pipetting, cartridge-based barrier pipetting for contamination prevention, and diaphragm-based isolation pipetting. Air-displacement pipetting relies on the pressure difference created by the reciprocating piston to achieve liquid aspiration and dispensing. Cartridge-based pipetting relies on an internal filter medium to prevent backflow of aerosols. Diaphragm-based isolation pipetting relies on an elastic membrane to separate the gas and liquid streams and transmit gas pressure. However, in situations involving diverse cell lines, varying sample rarity, frequent batches, and stringent aseptic requirements, these approaches have limitations: air-displacement pipetting lacks physical gas-liquid separation, allowing sample aerosols generated during operation to be drawn back into the internal cavity, easily causing cross-contamination. Cartridge-based pipetting... The filtration accuracy is a factory-preset fixed value. The protection level requirements for routine operation and high-risk sample handling are different. A single accuracy is not enough to ensure both smooth liquid flow and effective contamination prevention. The protective performance of the filter element decreases significantly after being wetted by liquid, and there is no immediate indication of failure. The membrane of the diaphragm-type isolation pipetting is prone to fatigue and aging due to long-term reciprocating deformation. Biological residues can easily accumulate in the gap between the membrane and the shell and are difficult to clean thoroughly. There is no intuitive way to identify membrane damage, and continued use can easily aggravate the accumulation of contamination in the internal cavity. The operating space at the mouth of the culture bottle and the cell of the multi-well plate is limited, and operational deviations can easily cause the pipette tip to touch the cavity wall, resulting in external contamination. Humid and hot gases and corrosive disinfectants in the experimental environment will accelerate the performance degradation and accuracy drift of piston seals and precision scale components. Summary of the Invention

[0004] The purpose of this invention is to provide a pipetting device for cell culture, which solves the problems mentioned in the background art, such as the lack of physical separation between air and liquid in air-displacement pipetting leading to aerosol backflow and cross-contamination, the elastic deformation of the membrane in diaphragm-type isolation pipetting introducing volume measurement deviation and the lack of intuitive identification after damage, and the inherent contradiction between filtration accuracy and smooth flow in filter cartridge-type pipetting.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a pipetting device for cell culture, comprising a housing, a piston mechanism installed inside the housing, a retraction mechanism sleeved on the lower part of the housing, and a conical tip connected to the lower end of the housing; The inner cavity of the cone head is detachably connected to a disposable diaphragm assembly; The disposable diaphragm assembly includes an upper base section and a lower base section coaxially connected. The upper base section has a second cavity at the top of its inner cavity and a second step in the middle of its inner wall. A first diaphragm and a second diaphragm are welded and fixed on the second step, forming a sealed indicator cavity between the two diaphragms. The upper section of the base has a lip ring on its outer wall, the lower section of the base has a flange on its outer edge, and the lower end of the lower section of the base has a plug-in structure, which is fitted with a suction head.

[0006] Preferably, the outer wall of the upper end of the cone head is provided with an external thread that is screwed and sealed to the lower end of the housing. The inner cavity of the cone head is provided with a first inner conical surface, a first cavity, a first step and a chamfer from top to bottom. The first inner conical surface is a cone shape that is narrower at the top and wider at the bottom. The first cavity is a cylindrical cavity with a constant diameter. The end face of the first step faces the lower opening side of the cone head. The chamfer is located at the lowermost opening of the cone head.

[0007] Preferably, both the first inner conical surface and the outer wall of the upper section of the base adopt a standard 1:10 taper, and the first inner conical surface and the upper section conical surface of the base are interference-fitted to form a surface seal. The inner diameter of the first cavity is larger than the lower end diameter of the first inner conical surface, so as to reserve radial elastic deformation space for the lip ring.

[0008] Preferably, the second cavity is an inverted shallow dome-shaped rigid cavity. A central vent is opened at the top of the second cavity. The central vent is connected to the driving air chamber below the piston mechanism through the inner cavity of the cone head. Multiple guide grooves are arranged on the inner wall of the second cavity. The multiple guide grooves are evenly arranged radially along the inner wall of the dome of the second cavity and extend from the edge of the central vent to the bottom edge of the cavity.

[0009] Preferably, the second step is a two-level coaxial annular step, the outer rings of the first diaphragm and the second diaphragm are respectively fused and fixed on the two-level steps, the two layers of the first diaphragm and the second diaphragm are arranged in parallel and the spacing is constant, and the sealed indicator cavity is pre-filled with sterile staining indicator solution.

[0010] Preferably, the lip ring is a V-shaped cantilever thin-walled structure with the opening facing downwards, with only the upper root being integrally connected to the outer wall of the upper section of the base, and the lower lip being a free-moving end. A uniform annular deformation gap is reserved between the inner side of the lip ring and the outer wall of the lower section of the base.

[0011] Preferably, the natural outer diameter of the lip ring is larger than the inner diameter of the first cavity, forming an initial interference fit. Under the negative pressure of liquid absorption, the lip of the lip ring expands outward and adheres tightly to the inner wall of the first cavity. Under the positive pressure of liquid discharge, the lip of the lip ring contracts inward and returns to its original position.

[0012] Preferably, the flange is a thin, annular horizontal edge that protrudes coaxially from the outer edge of the lower section of the base, and the top surface of the flange is a limiting and fitting surface perpendicular to the axis, which abuts against the end face of the first step to achieve axial positioning.

[0013] Preferably, the insertion structure is either a second inner conical surface or an outer conical interface; the second inner conical surface is formed on the inner wall of the lower section of the base, and is a cone shape that is narrower at the top and wider at the bottom. The upper end of the suction head is inserted into the second inner conical surface from bottom to top, and the seal is achieved by the interference fit of the conical surface; the outer conical interface extends coaxially to the bottom surface of the flange and extends out of the lower port of the conical head, and is a cone shape that is wider at the top and narrower at the bottom. The suction head is sleeved on the outside of the outer conical interface, and the seal is achieved by the interference fit of the conical surface.

[0014] Preferably, the upper section of the base, the lower section of the base, the lip ring, and the flange of the disposable diaphragm assembly are integrally injection molded structures, and the first diaphragm and the second diaphragm are fixed by secondary injection molding and welding to the second step.

[0015] Compared with the prior art, the beneficial effects of the present invention are: In this invention, the synergistic cooperation between the conical tip and the disposable diaphragm assembly effectively improves the problems of conventional air-displacement pipetting devices, such as the lack of physical separation between gas and liquid, which easily leads to aerosol cross-contamination; the rapid drop in protective performance of the filter element barrier structure after wetting and the lack of indication of failure; and the significant impact of material tolerances on the accuracy of diaphragm-type pipetting structures, as well as the difficulty in simultaneously achieving sealing reliability and insertion / removal feel. In the conical tip unit, the first inner conical surface cooperates with the upper section of the base to form the main sealing reference, the first cavity provides deformation space for the lip ring, the first step cooperates with the flange to achieve axial hard limiting, and the chamfer can guide the smooth insertion of the assembly, forming a unified assembly bearing base. In the disposable diaphragm assembly, the second cavity and the guide groove form a rigid constant volume and uniform pressure distribution structure, eliminating the dead zone of air pressure against the diaphragm wall, and changing the pipetting volume from elastic deformation measurement to rigid volume locking, reducing the impact of material tolerances and the environment. Fluctuations interfere with accuracy; the lip ring applies an adaptive clamping force to the inner wall of the first chamber based on the pressure difference, converting the negative pressure of liquid aspiration into a reverse clamping force to achieve a self-tightening seal, providing stable sealing conditions for the gas path side; the first and second diaphragms form a double isolation barrier, and the two-stage second-step seal retains independent redundancy characteristics, reducing the risk of contamination diffusion from single-point damage; the staining solution in the indicator chamber flows with the pressure difference to achieve intuitive identification of damage, avoiding the continued use of hidden failures; the flange, in conjunction with the retraction mechanism, enables contactless retraction and unloading, and the pipette tip insertion adopts a configurable form with a second inner conical surface or an outer conical interface, taking into account consumable compatibility and the need for full-path contamination prevention; the overall operation logic does not need to be changed, which can improve the contamination protection level and accuracy consistency of cell culture pipetting, reduce the performance degradation rate of long-term use, and adapt to high-frequency operation conditions of multiple samples and multiple cell lines. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the three-dimensional structure in this invention; Figure 2 This is a schematic diagram of the main view structure in this invention; Figure 3 This is a schematic diagram showing the installation position of the cone head and disposable diaphragm assembly in this invention; Figure 4 This is a schematic diagram of the mounting position of the cone head in this invention; Figure 5 for Figure 4 Enlarged detail image of point A in the middle; Figure 6 This is a schematic diagram of the structure of the disposable diaphragm assembly in this invention; Figure 7 This is a schematic diagram of the structure of the lower section of the base and the second inner conical surface in this invention; Figure 8 for Figure 7 Enlarged detail image at point B in the middle; Figure 9 This is a schematic diagram of the structure of the second inner conical surface and the lip ring in this invention; Figure 10 for Figure 9 Enlarged detail of section C; Figure 11 for Figure 9 Enlarged detail image of section D in the middle; Figure 12 This is a schematic diagram of the structure of the second step, the second cavity, and the guide groove in this invention.

[0017] In the diagram: 100, housing; 200, piston mechanism; 300, suction retraction mechanism; 400, cone head; 401, external thread; 402, first inner cone surface; 403, first cavity; 404, first step; 405, chamfer; 500, disposable diaphragm assembly; 501, upper section of base; 502, second step; 503, second cavity; 504, guide channel; 505, first diaphragm; 506, second diaphragm; 507, lower section of base; 508, second inner cone surface; 509, lip ring; 510, flange; 511, outer cone interface; 512, suction head. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] like Figures 1-3As shown, this embodiment provides a pipetting device for cell culture, including a housing 100, a piston mechanism 200, a retraction mechanism 300, a cone tip 400, and a disposable diaphragm assembly 500. The piston mechanism 200 is coaxially mounted inside the housing 100, the retraction mechanism 300 is sleeved on the lower outer side of the housing 100, the cone tip 400 is screwed and fixed to the lower end of the housing 100, and the disposable diaphragm assembly 500 is detachably inserted into the inner cavity of the cone tip 400, with a pipette tip 512 installed at its lower end. The overall device follows the operating logic of a manual pipette, achieving physical isolation of gas and liquid and rigid volume control through the disposable diaphragm assembly 500. It is suitable for high-cleanliness pipetting conditions such as reagent dispensing and cell seeding in cell culture, reducing the risk of cross-contamination caused by aerosol backflow and improving the long-term consistency of pipetting accuracy.

[0020] like Figures 4-5 As shown, the cone head 400 is a rotating structure and can be formed by medical-grade polypropylene or 304 stainless steel. The upper outer wall is machined with external threads 401, which are adapted to the internal threads at the lower end of the housing 100 for screwing. The screwing end face is fitted with a sealing gasket to achieve air circuit sealing, ensuring that the cone head 400 is easy to disassemble and assemble and that there is no air leakage in the air circuit. The inner cavity of the cone head 400 is machined from top to bottom with a first inner cone surface 402, a first cavity 403, a first step 404 and a chamfer 405, and the cavities are arranged coaxially and continuously.

[0021] The first inner conical surface 402 is a cone shape that is narrower at the top and wider at the bottom. The taper adopts the standard 1:10 taper commonly used in pipettes. The inner surface is mirror-polished and serves as the main sealing reference surface on the gas path side. The first cavity 403 is a cylindrical straight hole of equal diameter. Its inner diameter is larger than the lower end diameter of the first inner conical surface 402, forming a radial expansion space to accommodate the lip ring 509 of the disposable diaphragm assembly 500 and to reserve a margin for the radial elastic deformation of the lip ring 509. The first step 404 is naturally formed by the diameter difference between the lower end of the first cavity 403 and the upper end of the lower chamfer 405. It is an annular horizontal plane perpendicular to the axis, with its end face facing the lower opening side of the cone head 400, serving as the axial limiting reference for the insertion of the disposable diaphragm assembly 500. The chamfer 405 is set at the opening at the lowest end of the cone head 400. It is a trumpet-shaped conical surface that expands downward and outward. The opening edge is rounded and blunted to guide the disposable diaphragm assembly 500 to be smoothly inserted into the inner cavity, reducing the difficulty of alignment during single-handed operation.

[0022] like Figures 6-7As shown, the disposable diaphragm assembly 500 is an integrated coaxial rotating body structure. The main body is made of medical-grade polypropylene through precision injection molding, and the elastic diaphragm element is made of medical-grade thermoplastic elastomer through secondary injection molding and welding sealing. The finished product is individually packaged after gamma ray sterilization and is discarded after single use. The disposable diaphragm assembly 500 includes, from top to bottom, an upper base section 501, a second cavity 503, a second step 502, a first diaphragm 505, a second diaphragm 506, a lip ring 509, a lower base section 507, a flange 510, and a plug-in structure. All parts are coaxially arranged, and the structure is continuous without any breaks.

[0023] like Figure 7 as well as Figure 10 As shown, the upper section 501 of the base is the supporting frame of the disposable diaphragm assembly 500. Its outer wall is a smooth outer conical surface with a standard 1:10 taper, and the surface is mirror-polished. The taper accuracy perfectly matches the first inner conical surface 402 of the cone head 400. After the disposable diaphragm assembly 500 is inserted into place, the outer wall of the upper section 501 of the base and the first inner conical surface 402 are press-fitted together to form a surface seal structure, serving as the main seal on the gas path side. A second cavity 503 is provided at the top of the inner cavity of the upper section 501. The second cavity 503 is an inverted, shallow dome-shaped rigid cavity with a vent hole at the center of the top. The vent hole is connected to the driving air chamber below the piston mechanism 200. Figure 12 As shown, the geometric volume of the inner wall of the second cavity 503 corresponds to the maximum liquid transfer range of the device. Multiple guide grooves 504 are evenly distributed on the inner wall of the dome of the second cavity 503. The guide grooves 504 extend radially from the edge of the central vent hole to the bottom edge of the cavity, and the bottom of the grooves is rounded. When the liquid is drawn at full capacity, the diaphragm adheres to the inner wall of the cavity. The guide grooves 504 can ensure that the gas path is fully connected, avoid the diaphragm adsorbing on the cavity wall over a large area, which would cause reset delay, and at the same time make the gas pressure act evenly on the diaphragm surface.

[0024] like Figure 12 As shown, the inner wall of the base has two levels of second steps 502 in the middle. The two steps are coaxial ring structures and are staggered vertically along the axial direction. The first diaphragm 505 and the second diaphragm 506 are both flat circular elastic films. Their outer rings are fixed to the two levels of second steps 502 by secondary injection molding. The weld is completely sealed without leakage. The two diaphragms are arranged in parallel and enclosed in the middle to form a closed indicator cavity. The cavity is pre-filled with sterile methylene blue staining indicator solution. This structure forms a double isolation barrier. When any diaphragm is damaged, the pressure difference drives the staining solution to flow to the damaged side. The damage status can be visually identified through the transparent outer wall of the base.

[0025] like Figures 7-8As shown, a lip ring 509 is integrally provided on the lower middle part of the outer wall of the upper section 501 of the base. The axial position of the lip ring 509 corresponds to the first cavity 403 of the cone head 400. The axial section of the lip ring 509 is a V-shaped cantilever thin-walled structure with the opening facing downward. Only the upper root is integrally connected to the outer wall of the upper section 501 of the base, and the lower lip is a free-moving end. A uniform annular deformation gap is reserved between the inner side of the lip of the lip ring 509 and the outer wall of the lower section 507 of the base. The natural outer diameter of the lip ring 509 is slightly larger than the inner diameter of the first cavity 403. After initial assembly, a pre-compression interference of 0.1mm to 0.15mm is formed. Under the condition of liquid suction negative pressure, the air pressure on the outside of the lip ring 509 is lower than that on the inside. The pressure difference drives the lip to expand outward and stick tightly to the inner wall of the first cavity 403. The greater the negative pressure, the stronger the sticking force, thus realizing self-adaptive self-tightening seal.

[0026] like Figure 9 as well as Figure 11 As shown, the lower section 507 and the upper section 501 of the base are integrally injection molded continuous solids, forming a hollow cavity through which they are connected, constituting the upper cavity wall on the sample side; a flange 510 is coaxially protruding on the outer edge of the upper part of the lower section 507 of the base. The flange 510 is a ring-shaped horizontal thin edge, with the top surface being a flat and fitting surface perpendicular to the axis, and the bottom surface being the stress surface. All edges are rounded and blunted; the outer diameter of the flange 510 is between the inner diameter of the first step 404 and the inner diameter of the upper end of the chamfer 405. When the component is inserted into place, the top surface of the flange 510 abuts against the end face of the first step 404, achieving precise axial positioning.

[0027] like Figure 9 as well as Figure 11 As shown, the lower end of the lower section 507 of the base is provided with a pipette tip 512 insertion structure, which can be either built-in or external depending on the usage requirements. The built-in type is a second inner conical surface 508, which is opened in the inner wall of the lower section 507 of the base. It has a standard 1:10 taper with a narrower top and a wider bottom, and the inner surface is polished. The upper end of the pipette tip 512 is inserted into the second inner conical surface 508 from bottom to top, and the seal is achieved through the interference fit of the conical surface. The external type is an outer conical interface 511, which extends downward from the bottom surface of the flange 510 in the same direction. After assembly, it extends out of the lower port of the cone tip 400 and has a standard 1:10 taper with a wider top and a narrower bottom. The pipette tip 512 is fitted onto the outside of the outer conical interface 511 from bottom to top to achieve a seal. This form allows the cone tip 400 to not come into contact with the sample and aerosol throughout the process, further improving the anti-contamination level. The pipette tip 512 adopts a universal disposable sterile pipette tip, which is compatible with the taper of the insertion structure, and no special consumables are required.

[0028] The assembly sequence of this embodiment is as follows: First, the piston mechanism 200 is installed into the corresponding position inside the housing 100, and the push rod and push ring components of the suction mechanism 300 are installed; the cone 400 is screwed and fixed to the lower end of the housing 100 through the upper external thread 401, completing the assembly of the main body of the pipetting device; when in use, the sterilized disposable diaphragm assembly 500 is taken out, with the top facing upward and aligned with the lower opening of the cone 400, and pushed upward through the chamfer 405; the main body of the assembly passes through the inner hole of the first step 404, and the lip ring 509 is initially compressed by the inner wall of the first cavity 403, and is pushed in until the outer cone surface of the upper section 501 of the base is completely in contact with the first inner cone surface 402. At this time, the top surface of the flange 510 abuts against the first step 404, and is axially installed in place; finally, the pipette tip 512 is inserted into the insertion structure at the lower end of the assembly, and the pipetting operation can be performed.

[0029] The working process of this embodiment is divided into three stages: liquid aspiration, liquid drainage, and unloading.

[0030] During the liquid aspiration stage, the operation button drives the piston mechanism 200 upward, generating negative pressure in the air chamber. The air pressure is evenly applied to the upper surface of the first diaphragm 505 through the guide groove 504 of the second chamber 503. The two diaphragms simultaneously concave upward, and the suction head 512 simultaneously draws in liquid. At the same time, the negative pressure acts on the outside of the lip ring 509, creating a pressure difference between the inside and outside of the lip ring 509. This drives the lip to expand outward and adhere tightly to the inner wall of the first chamber 403. The higher the negative pressure value, the greater the adhesion force, and the sealing performance is simultaneously enhanced. When the liquid aspiration reaches full capacity, the first diaphragm 505 is completely attached to the inner wall of the dome of the second chamber 503. The liquid transfer volume is precisely locked by the geometric volume of the rigid chamber and is not affected by the elastic tolerance of the diaphragm.

[0031] During the drainage stage, the piston mechanism 200 moves downward, generating positive pressure in the driving air chamber, which pushes the two diaphragms to bulge downward and reset, discharging the liquid in the suction head 512. At this time, the air pressure on the outside of the lip ring 509 is higher than that on the inside. The pressure difference pushes the lip to contract inward, reducing the friction force against the wall and preventing the components from loosening due to the positive pressure.

[0032] During the unloading phase, press the operation button of the suction unloading mechanism 300. The annular push ring slides downward along the outer wall of the cone head 400. The lower end face of the push ring abuts against the annular shoulder of the upper end of the suction head 512. The downward thrust is transmitted to the lower section 507 of the base through the mating surface of the suction head and the plug-in structure, causing the top surface of the flange 510 to detach from the end face of the first step 404. The disposable diaphragm assembly 500, together with the suction head 512, simultaneously detaches downward from the cone head 400. No human hand contact with consumables is required throughout the process, meeting the requirements for aseptic operation.

[0033] When the diaphragm is damaged, if the upper first diaphragm 505 breaks, the pressure difference on the gas path side will drive the staining solution in the indicator chamber to flow upward. The color can be observed to diffuse towards the second chamber 503 through the transparent base. At this time, the lower second diaphragm 506 remains intact and can maintain basic isolation function. If the lower second diaphragm 506 breaks, the staining solution flows downward to the sample chamber, and the color can be observed to diffuse towards the pipette tip 512. At this time, the upper diaphragm can still block gas path contamination. In both states, the operator can identify the damage in time by color change and replace the component in time to avoid contamination caused by hidden failure.

[0034] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A pipetting device for cell culture, comprising a housing (100), a piston mechanism (200) installed inside the housing (100), a retraction mechanism (300) sleeved on the lower part of the housing (100), and a cone tip (400) connected to the lower end of the housing (100), characterized in that: The inner cavity of the cone (400) is detachably connected to a disposable diaphragm assembly (500). The disposable diaphragm assembly (500) includes an upper base section (501) and a lower base section (507) coaxially connected. The upper base section (501) has a second cavity (503) at the top of its inner cavity and a second step (502) in the middle of its inner wall. A first diaphragm (505) and a second diaphragm (506) are welded and fixed on the second step (502), forming a sealed indicator cavity between the two diaphragms. The upper section (501) of the base is provided with a lip ring (509) on its outer wall, the lower section (507) of the base is provided with a flange (510) on its outer edge, and the lower end of the lower section (507) of the base is provided with a plug-in structure, and the plug-in structure is equipped with a suction head (512).

2. The pipetting device for cell culture according to claim 1, characterized in that: The upper outer wall of the cone (400) is provided with an external thread (401) and is screwed and sealed to the lower end of the housing (100). The inner cavity of the cone (400) is provided with a first inner cone surface (402), a first cavity (403), a first step (404) and a chamfer (405) from top to bottom. The first inner cone surface (402) is a cone shape that is narrow at the top and wide at the bottom. The first cavity (403) is a cylindrical cavity with equal diameter. The end face of the first step (404) faces the lower opening side of the cone (400). The chamfer (405) is located at the lowermost opening of the cone (400).

3. The pipetting device for cell culture according to claim 2, characterized in that: The first inner conical surface (402) and the outer wall of the upper section of the base (501) both adopt a standard 1:10 taper, and the first inner conical surface (402) and the conical surface of the upper section of the base (501) are press-fitted to form a surface seal. The inner diameter of the first cavity (403) is larger than the lower end diameter of the first inner conical surface (402), which reserves radial elastic deformation space for the lip ring (509).

4. The cell culture pipetting device according to claim 1, characterized in that: The second cavity (503) is an inverted shallow dome-shaped rigid cavity. A central vent hole is opened at the top of the second cavity (503). The central vent hole is connected to the driving air chamber below the piston mechanism (200) through the inner cavity of the cone head (400). A plurality of guide grooves (504) are arranged on the inner wall of the second cavity (503). The plurality of guide grooves (504) are evenly arranged radially along the inner wall of the dome of the second cavity (503) and extend from the edge of the central vent hole to the bottom edge of the cavity.

5. The cell culture pipetting device according to claim 1, characterized in that: The second step (502) is a two-level coaxial annular step. The outer rings of the first diaphragm (505) and the second diaphragm (506) are respectively fused and fixed on the two steps. The first diaphragm (505) and the second diaphragm (506) are arranged in parallel with a constant spacing. The sealed indicator cavity is pre-filled with sterile staining indicator solution.

6. The pipetting device for cell culture according to claim 2, characterized in that: The lip ring (509) is a V-shaped cantilever thin-walled structure with the opening facing downwards. Only the upper root is integrally connected to the outer wall of the upper section (501) of the base, and the lower lip is a free movable end. A uniform annular deformation gap is reserved between the inner side of the lip ring (509) and the outer wall of the lower section (507) of the base.

7. The cell culture pipetting device according to claim 6, characterized in that: The natural outer diameter of the lip ring (509) is larger than the inner diameter of the first cavity (403), forming an initial interference. Under the negative pressure of liquid absorption, the lip of the lip ring (509) expands outward and adheres tightly to the inner wall of the first cavity (403). Under the positive pressure of liquid discharge, the lip of the lip ring (509) contracts inward and resets.

8. The pipetting device for cell culture according to claim 2, characterized in that: The flange (510) is a thin, annular horizontal edge that protrudes coaxially from the outer edge of the lower section (507) of the base. The top surface of the flange (510) is a limiting and fitting surface perpendicular to the axis, which abuts against the end face of the first step (404) to achieve axial positioning.

9. The pipetting device for cell culture according to claim 1, characterized in that: The insertion structure is either a second inner conical surface (508) or an outer conical interface (511); the second inner conical surface (508) is opened on the inner wall of the lower section (507) of the base, and is a cone shape that is narrow at the top and wide at the bottom. The upper end of the suction head (512) is inserted into the second inner conical surface (508) from bottom to top, and the seal is achieved by the interference fit of the conical surface; the outer conical interface (511) extends coaxially to the bottom surface of the flange (510) and extends out of the lower port of the cone head (400), and is a cone shape that is wide at the top and narrow at the bottom. The suction head (512) is sleeved on the outside of the outer conical interface (511), and the seal is achieved by the interference fit of the conical surface.

10. The pipetting device for cell culture according to claim 1, characterized in that: The upper section (501), lower section (507), lip ring (509), and flange (510) of the disposable diaphragm assembly (500) are integral injection molded structures. The first diaphragm (505) and the second diaphragm (506) are fused and fixed to the second step (502) through secondary injection molding.

Images