A liquid pumping mechanism, droplet generation system and digital PCR apparatus

Abstract

The utility model relates to a kind of liquid pumping mechanism, droplet generation system and digital PCR equipment.The droplet generation system and digital PCR equipment all include liquid pumping mechanism, and liquid pumping mechanism includes plunger pump, motor, lead screw nut transmission mechanism connecting motor and plunger pump and elastic structure, and plunger pump includes pump body, the plunger of sliding connection with pump body, lead screw nut transmission mechanism includes lead screw, nut and transmission seat, transmission seat is connected with the plunger of plunger pump, and lead screw nut transmission mechanism is driven under the motor plunger and is pushed towards first direction movement to realize liquid pumping, and elastic structure is used to provide opposite plunger with the counterthrust opposite first direction when plunger towards first direction movement.The utility model utilizes the counterthrust provided by elastic structure to make nut be always compressed in the thread groove on lead screw, and nut and transmission seat are subjected to stable driving force and move at uniform speed, eliminate the clearance vibration generated in lead screw driving process, realize the stable liquid output of flow.

Description

Technical Field

[0001] This utility model relates to a digital PCR device, and particularly to the liquid pumping mechanism and droplet generation system in the device. Background Technology

[0002] In digital PCR equipment, a liquid pumping mechanism is used to output liquid for droplet generation. The stability of the liquid flow rate is crucial for achieving the desired droplet size and uniformity. See Chinese invention patent application number 202111335113.3, whose droplet generation system includes a variable-volume receiving cavity, a droplet generation tube, and a driving fluid mechanism for introducing driving fluid into the receiving cavity. The driving fluid mechanism, serving as the liquid pumping mechanism, includes pumps. It employs two plunger pumps of different volumes to control the driving fluid, using a three-way valve for switching control. The larger plunger pump is used in the cleaning and / or defoaming steps, while the smaller plunger pump is used in the droplet formation step. See Chinese invention patent application number 202111335117.1, whose droplet generation mechanism includes a sample dispensing tube comprising a base, a connector, and a nozzle. A first lumen is formed within the base, and one end of the first lumen forms a liquid injection port, which is connected to the plunger pump used as the liquid pumping mechanism. After the nozzle draws in water (reagent), the plunger pump pushes it at a set input speed, driving the hydraulic oil in the liquid path to generate thrust, propelling the water (reagent) within the nozzle. Simultaneously, vibration forms droplets within the nozzle. The plunger pump can be driven by a screw-nut transmission mechanism, where the nut is threaded onto the screw and moves along the screw axis. The nut is also connected to the plunger of the plunger pump, so its movement drives the plunger to move synchronously, slowly pushing the liquid out of the plunger pump. However, this liquid pumping mechanism is susceptible to mechanical vibration, particularly flow fluctuations caused by the gap vibration of the screw. This is because the driving force on the nut is not uniform but periodically changing when the screw drives the nut. Therefore, this structure struggles to achieve stable liquid output, fails to meet the requirements for precise flow output, and is not conducive to obtaining stable, uniform droplets. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide an improved liquid pumping mechanism based on a lead screw nut, which can achieve stable liquid output and is particularly suitable for controlling the delivery of liquid in a digital PCR droplet generation system.

[0004] To solve the above technical problems, the present invention adopts the following technical solution:

[0005] A liquid pumping mechanism includes a plunger pump, a motor, and a screw-nut transmission mechanism connecting the motor and the plunger pump. The plunger pump includes a pump body and a plunger slidably connected to the pump body. The screw-nut transmission mechanism includes a screw, a nut, and a transmission seat. The screw is connected to the motor, the nut is connected to the transmission seat, and the transmission seat is connected to the plunger of the plunger pump. Driven by the motor, the screw-nut transmission mechanism pushes the plunger to move in a first direction to achieve liquid pumping. The liquid pumping mechanism also includes an elastic structure for providing a counter-thrust force opposite to the first direction to the plunger when it moves in the first direction.

[0006] According to a specific embodiment of the present invention, the elastic structure includes an elastic element, and the axial extension direction of the elastic element is consistent with the first direction.

[0007] Preferably, the axis of the elastic element is coplanar with the axis of the lead screw.

[0008] In a preferred and specific embodiment, the elastic element is a spring.

[0009] Furthermore, the elastic element is sleeved on the outer periphery of the lead screw, or the elastic element includes a first elastic element and a second elastic element symmetrically distributed on both sides of the lead screw.

[0010] According to a specific embodiment of the present invention, when the plunger moves toward the first direction, the elastic force generated by the compression of the elastic element forms the counter-thrust force, and the elastic element is configured such that the counter-thrust force generated by its compression is always less than the pushing force of the lead screw nut transmission mechanism on the plunger.

[0011] By adding two elastic elements, such as springs, that provide counter-thrust, the backlash vibration generated by the lead screw itself can be eliminated. The principle is that when the lead screw drives the nut to move upward (towards the first direction), the upward force is not uniform at the microscopic level, but changes periodically due to the load resistance. Therefore, after adding the springs, the downward (opposite to the first direction) counter-force of the springs causes the lead screw nut to be pressed tightly against the ball groove of the lead screw, thus creating a dynamic transmission seat that can move upward at a constant speed and in a micrometer-scale. This transmission seat pushes the plunger of the plunger pump to move upward at a constant speed, thus generating a stable flow pressure in the plunger pump, and finally obtaining a stable flow output.

[0012] According to a preferred embodiment of the present invention, the liquid pumping mechanism includes a horizontally extending mounting plate and a support plate vertically disposed on the mounting plate. A pair of connecting seats are disposed on the mounting plate. The lead screw is horizontally disposed and its two ends are respectively rotatably connected to the pair of connecting seats. The nut is threadedly connected to the lead screw. The transmission seat is respectively connected to the mounting plate. The elastic structure is horizontally arranged, and its two ends are respectively connected to the support plate and the transmission seat.

[0013] Preferably, the transmission seat extends through the mounting plate, the elastic structure, the lead screw, and the nut are located on one side of the mounting plate, and the plunger pump is located on the opposite side of the mounting plate.

[0014] Furthermore, the liquid pumping mechanism further includes a guiding mechanism, which comprises a guide rail disposed on one of the transmission base and the mounting plate, and a guide groove disposed on the other of the transmission base and the mounting plate, wherein the guide rail and the guide groove are slidably connected. Preferably, both the guide rail and the guide groove are straight.

[0015] Preferably, the mounting plate is provided with a valve plate, and the valve plate is provided with a three-way valve, and the pump body of the plunger pump is electrically connected to one port of the three-way valve on the valve plate.

[0016] Preferably, the motor is a stepper motor with a step angle of less than or equal to 0.9 degrees, which can control the flow rate more precisely.

[0017] Furthermore, a liquid pipe is provided inside the pump body, and the ratio of the inner diameter to the length of the liquid pipe is less than or equal to 1.2 / 30 and greater than 0. This suitable inner diameter-to-length ratio can achieve higher flow control accuracy.

[0018] Another aspect of this invention provides a droplet generation system, which includes the liquid pumping mechanism described above.

[0019] Furthermore, the droplet generation system is a system that provides droplets required for digital PCR detection.

[0020] In another aspect, this invention provides a digital PCR device, which includes a liquid pumping mechanism or droplet generation system as described above, enabling more stable, uniform, and controllable acquisition of the required droplets and corresponding detection.

[0021] Due to the application of the above technical solution, this utility model has the following advantages compared with the prior art: For the needs of digital PCR and other applications that require precise flow control and ensure stability, this utility model improves the screw-nut pumping mechanism by adding an elastic structure to provide a counter-thrust force opposite to the first direction to the plunger when the plunger moves in the first direction. This ensures that the nut is always pressed into the thread groove on the screw, and the nut and transmission seat are always subjected to a stable driving force, effectively eliminating the gap vibration generated during the screw drive process, thereby achieving stable liquid output. Attached Figure Description

[0022] Appendix Figure 1 This is a schematic diagram of the overall structure of a digital PCR device.

[0023] Appendix Figure 2 This is a first-view perspective perspective of the liquid pumping mechanism of this utility model.

[0024] Appendix Figure 3 This is a two-dimensional schematic diagram of the liquid pumping mechanism of this utility model from a second perspective.

[0025] In the attached diagrams: 1. Housing; 2. X-axis slide rail; 3. Y-axis slide rail; 4. Moving detection platform; 5. Drive unit; 6. Microdroplet generation unit; 7. Optical detection unit; 8. Moving load-bearing platform; 9. Drive screw; 10. Thermal circulation unit; 11. Oil supply unit; 12. Oil pumping unit; 13. Vibration unit; 14. Plunger pump; 15. Motor; 16. Screw; 17. Nut; 18. Transmission seat; 19. Base; 20. First spring; 21. Second spring; 22. Mounting plate; 23. Support plate; 24. Connecting seat; 25. Guide rail; 26. Guide groove; 27. Valve plate. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. 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 should fall within the protection scope of the present invention.

[0027] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0029] As attached Figure 1 The digital PCR device shown includes a housing 1, an X-axis slide rail 2 mounted on the housing 1, a Y-axis slide rail 3 mounted inside the housing 1, a movable detection platform 4 slidably mounted on the housing 1 via the X-axis slide rail 2, a drive device 5 for driving the movable detection platform 4 to move, a microdroplet generation unit 6 (i.e., a droplet generation system) mounted on the movable detection platform 4, an optical detection unit 7 mounted on the movable detection platform 4, a movable support platform 8 mounted inside the housing 1 via the Y-axis slide rail 3, a drive screw 9 for driving the movable support platform 8 to move, and multiple thermal circulation units 10 mounted on the movable support platform 8. The microdroplet generation unit 6 for micro-droplet processing of samples includes an oil supply unit 11 for providing oil (formulated oil), an oil pumping unit 12 for obtaining and pumping oil from the oil supply unit 11, a droplet generating nozzle (not shown in the figure) for obtaining the oil pumped by the oil pumping unit 12 and capable of aspirating the sample and outputting droplets, and a vibration unit 13 for vibrating the liquid in the droplet generating nozzle to form droplets. The oil supply unit 11 and the oil pumping unit 12, and the oil pumping unit 12 and the droplet generating nozzle are connected by pipelines. The oil pumping unit 12 first draws oil from the oil supply unit 11 and then slowly pumps it into the droplet generating nozzle to expel any gas. After the droplet generating nozzle aspirates the sample, microdroplets are formed and discharged under the vibration of the vibration unit 13.

[0030] The oil pumping unit 12 adopts the following structure of liquid pumping mechanism.

[0031] As attached Figure 2 and attached Figure 3 As shown, the liquid pumping mechanism includes multiple plunger pumps 14 arranged in a row, a motor 15, and a screw-nut transmission mechanism. The screw-nut transmission mechanism connects the motor 15 and the plunger pumps 14 respectively. The power output by the motor 15 is transmitted to the plunger pumps 14 through the screw-nut transmission mechanism, thereby driving the plunger pumps 14. Specifically, the plunger pump 14 includes a cylindrical pump body and a plunger slidably connected to the pump body. The plunger is inserted into the pump body and can slide along the axial direction of the pump body. When the plunger slides in different directions, it can draw liquid into the pump body or pump liquid out of the pump body.

[0032] The motor 15 is preferably a servo motor or a stepper motor, especially a stepper motor 15 with a step angle of less than or equal to 0.9 degrees.

[0033] The lead screw and nut transmission mechanism includes a lead screw 16, a nut 17, and a transmission seat 18. The lead screw 16 is coaxially connected to the output shaft of the motor 15, the nut 17 is threadedly connected to the lead screw 16, and the nut 17 is connected to the transmission seat 18. The plunger of the plunger pump 14 is also connected to the transmission seat 18. The transmission seat 18 is symmetrically arranged about the plane containing the center of the nut 17. When the lead screw 16 rotates, the nut 17 and the transmission seat 18 move together along the axial direction of the lead screw 16, causing the plunger to move relative to the pump body. When pumping liquid, the lead screw and nut transmission mechanism, driven by the motor 15, pushes the plunger in the first direction; when drawing in liquid, the lead screw and nut transmission mechanism, driven by the motor 15, pushes the plunger in the opposite direction. Furthermore, the liquid pumping mechanism also includes an elastic structure that provides a counter-thrust force opposite to the first direction to the plunger, the nut 17, and the transmission seat 18 when the plunger moves in the first direction. When the lead screw 16 rotates, it provides a driving force to the nut 17 in the first direction. Under the action of this counter-thrust, the nut 17 is attached to the side groove wall on the lead screw 16 where the driving force is provided, thereby preventing the nut 17, the transmission seat 18 and the plunger from vibrating due to the gap between the nut 17 and the lead screw 16, so that the plunger can advance smoothly.

[0034] In the illustrated embodiment, the elastic structure includes an elastic element whose axial direction is aligned with the first direction. Specifically, the elastic element may be a spring. The elastic element may be sleeved around the outer periphery of the lead screw 16 or symmetrically distributed on both sides of the lead screw 16 to provide a balanced counter-thrust force. In this embodiment, the elastic element includes a first elastic element and a second elastic element, namely a first spring 20 and a second spring 21, which are symmetrically distributed on both sides of the lead screw 16 axially. The axis of the elastic element is coplanar with the axis of the lead screw 16, or the axis of the elastic element is not coplanar with the axis of the lead screw 16 but can still provide a balanced counter-thrust force on both sides.

[0035] When the plunger moves in the first direction, the elastic force generated by the compression of the elastic element forms a counter-thrust force. The elastic element is configured such that the counter-thrust force generated by its compression is always less than the pushing force of the screw nut transmission mechanism on the plunger, or in other words, the counter-thrust force provided by the elastic element to the nut 17 and the transmission seat 18 is always less than the driving force of the screw 16 on the nut 17.

[0036] The liquid pumping mechanism also includes a mounting plate 22 and a support plate 23 for mounting the various components. Specifically, the surface of the mounting plate 22 is parallel to the first direction, and the support plate 23 is mounted on the mounting plate 22 with its surface perpendicular to the mounting plate 22. For example, the mounting plate 22 can extend horizontally, while the support plate 23 is vertically mounted on the mounting plate 22. The elastic structure, lead screw 16, nut 17, and transmission seat 18 are located on one side of the mounting plate 22, and the plunger pump 14 is located on the opposite side of the mounting plate 22. On the side where the lead screw 16 is located, a pair of connecting seats 24 are spaced apart on the mounting plate 22. The lead screw 16 is arranged horizontally along the direction parallel to the surface of the mounting plate 22, and its two ends are rotatably connected to a pair of rotating seats. The transmission seat 18 is slidably connected to the mounting plate 22. The elastic structure is also arranged horizontally along the direction parallel to the surface of the mounting plate 22, and its two ends are connected to the support plate 23 and the transmission seat 18, respectively. The transmission seat 18 is disposed through the mounting plate 22 for connection of the plunger pump 14. On the side where the plunger pump 14 is located, a base 19 connected to the transmission seat 18 can also be disposed, and the plunger of the plunger pump 14 can be connected to the base 19.

[0037] The liquid pumping mechanism further includes a guiding mechanism, which is located on the side of the mounting plate 22 where the transmission seat 18 is located. The guiding mechanism includes a linear guide rail 25 mounted on one of the transmission seat 18 and the mounting plate 22, and a linear guide groove 26 mounted on the other of the two. The guide rail 25 and the guide groove 26 are slidably connected. There are two guide rails 25 and two guide grooves 26, respectively located on both sides of the lead screw 16. The guiding mechanism further ensures the linearity and stability of the drive operation. In this embodiment, the guide rail 25 is mounted on the mounting plate 22, and the guide groove 26 is mounted on the transmission seat 18.

[0038] A valve plate 27 is provided on the mounting plate 22 on one side of the plunger pump 14. The valve plate 27 has three-way valves corresponding to the plunger pump 14. The pump body of the plunger pump 14 is connected to one port of the three-way valve on the valve plate 27. The other two ports of the three-way valve are connected to the oil supply unit 11 and the droplet generating nozzle respectively via pipelines. Therefore, in different open / closed states of the three-way valves, the oil supply unit 11 can supply oil to the plunger pump 14, or pump the oil out of the plunger pump 14 and send it to the droplet generating nozzle.

[0039] For the plunger pump 14, a liquid tube is provided inside the pump body. The ratio of the inner diameter to the length of the liquid tube is less than or equal to 1.2 / 30 and greater than 0. The preferred value for the ratio of the inner diameter to the length of the liquid tube is 1 / 60. The plunger pump 14 with its slender liquid tube structure can achieve a liquid flow control accuracy of nanoliters per second. In conjunction with the lead screw nut transmission mechanism that eliminates lead screw backlash vibration, the plunger is pushed by the transmission seat 18, enabling the plunger to achieve uniform and stable movement, generating a stable flow pressure within the plunger pump 14, and ultimately obtaining a stable flow output when pumping liquid.

[0040] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. A liquid pumping mechanism, characterized in that: The device includes a plunger pump, a motor, and a screw-nut transmission mechanism connecting the motor and the plunger pump. The plunger pump includes a pump body and a plunger slidably connected to the pump body. The screw-nut transmission mechanism includes a screw, a nut, and a transmission seat. The screw is connected to the motor, the nut is connected to the transmission seat, and the transmission seat is connected to the plunger of the plunger pump. Driven by the motor, the screw-nut transmission mechanism pushes the plunger to move in a first direction to achieve liquid pumping. The liquid pumping mechanism also includes an elastic structure for providing a counter-thrust force opposite to the first direction to the plunger when it moves in the first direction.

2. The liquid pumping mechanism according to claim 1, characterized in that: The elastic structure includes an elastic element, and the axial extension direction of the elastic element is consistent with the first direction.

3. The liquid pumping mechanism according to claim 2, characterized in that: The axis of the elastic element is coplanar with the axis of the lead screw.

4. The liquid pumping mechanism according to claim 2, characterized in that: The elastic element is a spring.

5. The liquid pumping mechanism according to any one of claims 2-4, characterized in that: The elastic element is sleeved on the outer periphery of the lead screw, or the elastic element includes a first elastic element and a second elastic element symmetrically distributed on both sides of the lead screw.

6. The liquid pumping mechanism according to claim 2, characterized in that: When the plunger moves in the first direction, the elastic force generated by the compression of the elastic element forms the counter-thrust force. The elastic element is configured such that the counter-thrust force generated by its compression is always less than the pushing force of the lead screw and nut transmission mechanism on the plunger.

7. The liquid pumping mechanism according to claim 1, characterized in that: The liquid pumping mechanism includes a horizontally extending mounting plate and a support plate vertically mounted on the mounting plate. A pair of connecting seats are provided on the mounting plate. The lead screw is horizontally positioned and its two ends are rotatably connected to the pair of connecting seats respectively. The nut is threadedly connected to the lead screw. The transmission seat is connected to the mounting plate. The elastic structure is horizontally arranged, and its two ends are connected to the support plate and the transmission seat respectively.

8. The liquid pumping mechanism according to claim 7, characterized in that: The transmission seat extends through the mounting plate. The elastic structure, the lead screw, and the nut are located on one side of the mounting plate, and the plunger pump is located on the opposite side of the mounting plate.

9. The liquid pumping mechanism according to claim 7, characterized in that: The liquid pumping mechanism further includes a guiding mechanism, which includes a guide rail disposed on one of the transmission base and the mounting plate, and a guide groove disposed on the other of the transmission base and the mounting plate, wherein the guide rail and the guide groove are slidably connected.

10. The liquid pumping mechanism according to claim 7, characterized in that: The mounting plate is provided with a valve plate, and the valve plate is provided with a three-way valve. The pump body of the plunger pump is electrically connected to one port of the three-way valve on the valve plate.

11. The liquid pumping mechanism according to claim 1, characterized in that: The motor is a stepper motor with a step angle of less than or equal to 0.9 degrees.

12. The liquid pumping mechanism according to claim 1, characterized in that: The pump body is equipped with a liquid pipe, and the ratio of the inner diameter to the length of the liquid pipe is less than or equal to 1.2 / 30 and greater than 0.

13. A droplet generation system, characterized in that: Includes the liquid pumping mechanism as described in any one of claims 1-12.

14. The droplet generation system according to claim 13, characterized in that: The droplet generation system is a system that provides the droplets required for digital PCR detection.

15. A digital PCR device, characterized in that: Includes a liquid pumping mechanism as described in any one of claims 1-12 or a droplet generation system as described in claim 13.

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