A sealing structure with variable guide length and a pipetting system

Abstract

This invention discloses a variable guide length sealing structure, characterized by comprising a lead screw motor, a base plate, a transmission block, a lead screw nut, a guide rail, a plunger, a body, and a tip mounting structure. The lead screw motor is connected to the transmission block via the lead screw nut, and the transmission block is mounted on the guide rail and slides along the guide rail. The transmission block is also floatingly connected to the plunger. A tail guide ring is provided at the end of the plunger away from the transmission block, and a piston channel is formed on the inner wall of the body, with the plunger slidably mounted within the body. This application features dual guidance in its structure; the tail guide ring changes position with the movement of the plunger, maintaining the coaxiality of the plunger and the inner cavity of the body. During liquid discharge, this application can match different motion parameters to liquids of different viscosities based on the viscosity differences detected during aspiration, achieving optimal pipetting effect and avoiding liquid residue at the tip of the tip, especially with significant advantages in micro-volume pipetting of 2μl to 5μl.

Description

Technical Field

[0001] This invention relates to the field of automated sample and reagent pipetting, specifically to a variable guide length sealing structure and pipetting system. Background Technology

[0002] In the in vitro diagnostics industry, most automated instruments require automatic transfer and addition of reagents and samples (hereinafter referred to as automated pipetting). However, they are very sensitive to liquid residues, especially molecular diagnostic instruments, which are extremely sensitive to sample residues. Even a very small amount of residue can seriously affect the test results. In this case, the common solution is to use a pipetting pump with disposable tips, which eliminates the hassle of liquid tubing and avoids cross-contamination of liquid residues and samples.

[0003] Currently, in the field of automated sample and reagent pipetting, the following four types of pipetting pumps are commonly used:

[0004] 1) There is no guiding structure, only a sealing structure; for example, the Chinese utility model patent with authorization announcement number CN210114717U discloses a high-sealing syringe, which has only two sealing structures with inclined angles.

[0005] 2) The guiding and sealing structures are made together, but the guiding structure is only on the side away from the liquid outlet; for example, the extended embodiment in the invention patent with authorization announcement number CN1288426C.

[0006] 3) The guide and seal are separated, but the guide structure is only on the side away from the liquid outlet; for example, the invention patent with authorization announcement number CN1288426C discloses a maintenance-free syringe in which the seal and pressure ring are placed in the inner hole of the head of the body and are pressed down by the syringe cap. The plunger passes through the central hole of the syringe cap, pressure ring and seal in sequence and is inserted into the central cavity of the body.

[0007] 4) The structure of a conventional piston-type pipette pump; this structure is suitable for manual piston pushing. Because it uses electromechanical power as the power source, when the transmission thrust does not coincide with the axis of the cavity, it will force the sealing ring to deform to achieve movement, which can easily lead to seal failure.

[0008] In the above schemes 1-3, since the piston and the sealing or guiding structure need a gap to move relative to each other, the existence of the gap will cause the axis of the plunger and the axis of the cavity to have a tilt angle α that is different from the axis. The relationship between the distance t of the axis tilt offset, the angle α, and the distance L between the piston tail end and the guiding part is t = tanα * L. When the piston is close to the guiding part and away from the liquid outlet, the value of t is very small and the impact is minimal. However, when the piston tail end is close to the liquid outlet, similar to the lever principle, the value of t will be magnified many times. The plunger may rub against the inner wall of the cavity, which may lead to wear, burrs, etc. in the long run, ultimately reducing the sealing life.

[0009] Furthermore, current pipetting pump systems do not differentiate in terms of dispensing parameters for liquids of different viscosities, let alone automatically match motion parameters. They basically use the parameters directly from deionized water for testing. However, since pipetting pumps need to pipette samples and reagents of different viscosities, liquid residue is prone to occur at the tip of the tip during pipetting, especially for high-viscosity liquids. This affects pipetting accuracy, particularly for micro-volume pipetting of 2μl to 5μl. Liquid residue often results in pipetting repeatability and accuracy far exceeding the nominal value. Summary of the Invention

[0010] To overcome the problems existing in the prior art, this invention provides a sealing structure and pipetting system with variable guide length. Structurally, it features dual guidance; the tail guide ring changes position as the plunger moves, effectively maintaining the coaxiality of the plunger and the internal cavity of the pipetting system, avoiding the effects of misalignment. Pressure data is collected using a pressure sensor and converted into liquid viscosity. Different motion parameters are matched for liquids of different viscosities to ensure pipetting accuracy.

[0011] To achieve the above objectives, the present invention provides the following technical solution: a sealing structure with variable guide length, comprising a lead screw motor, a base plate, a transmission block, a lead screw nut, a guide rail, a plunger, a body, and a tip mounting structure;

[0012] The aforementioned tip installation structure includes a tip unload sleeve, a tip unload column, a tip installation column, and a tip header;

[0013] The lead screw motor is connected to the transmission block via a lead screw nut. The transmission block is mounted on the guide rail and slides along the guide rail. The transmission block is also floatingly connected to the plunger. A tail guide ring is provided at the end of the plunger away from the transmission block, and a sealing ring is provided at the connection between the tail guide ring and the plunger. A piston channel is formed on the inner wall of the body, and the plunger is slidably installed in the body.

[0014] The invention is further configured such that a compression spring is provided between the transmission block and the plunger. This is intended to eliminate the backlash error in floating transmissions.

[0015] The tail guide ring changes position as the plunger moves, so the effective guide length of the plunger is always a large proportion, which can maintain the coaxiality of the plunger and the inner cavity of the body and avoid the effects of misalignment.

[0016] The invention is further configured such that: the base plate also includes a motor mounting block and a pressure plate, the lead screw motor is mounted on the motor mounting block, and the track is set next to the lead screw motor.

[0017] The invention is further configured such that the variable guide length sealing structure also includes a body fixing block, the body fixing block is provided with a through hole, the body passes through the through hole and is fixed in the body fixing block by a guide ring; the tip unloading sleeve is provided at the bottom of the body fixing block and covers the part of the body that passes through the body fixing block.

[0018] The present invention is further configured such that: a stop block is installed on one end of the main body fixing block near the transmission block, and an optocoupler PCBA and a pressure sensor are arranged on the side; the optocoupler PCBA has a zero-position optocoupler and a tip detection optocoupler; and an optocoupler baffle is installed on the transmission block.

[0019] The invention is further configured such that: a through hole is provided on the side of the main body, which is connected to the pressure sensor through a capillary tube for collecting pressure change data within the main body; the main body is also provided with an exhaust hole to keep the pressure in the gap between the guide ring and the sealing ring consistent with the outside, thereby avoiding the influence of pressure difference caused by trapped air and improving the precision of pipetting.

[0020] The invention is further configured such that: a tip unloading post is provided inside the main body fixing block, and a spring is sleeved around the tip unloading post; the tip unloading post is connected to the tip unloading sleeve. The spring is used to keep the tip unloading post facing upwards, preventing interference with the position of the tip unloading sleeve. A protruding baffle is provided on one side of the tip unloading sleeve, and a contact plate is provided on the other side; the tip unloading post and the tip unloading sleeve are connected through the contact plate.

[0021] The present invention is further configured such that: the end of the tip unloading sleeve near the pipette port is connected to the tip mounting post, and the tip head is mounted on the tip mounting post.

[0022] This invention also provides a pipetting system suitable for the aforementioned variable guide length sealing structure, enabling pressure acquisition and viscosity conversion for liquid aspiration and optimal matching of motion parameters for liquid discharge, comprising the following steps:

[0023] S1: Before liquid aspiration, the pressure sensor collects the atmospheric pressure AD value N1;

[0024] S2: Pressure sensor collects pressure AD value N2 during liquid aspiration;

[0025] S3: Transmit the pressure AD values ​​N1 and N2 to the control software;

[0026] S4: The control software converts the difference ΔN between N1 and N2 into liquid viscosity using an algorithm;

[0027] S5: When the pipette pump performs the dispensing action, the control software automatically matches the motion parameters according to the calculation results and sends different pulse frequency signals to the motor;

[0028] S6: After receiving a pulse signal, the motor discharges liquid at different speeds.

[0029] The present invention is further configured such that the motion parameter is the drainage speed obtained by actual testing and verification of liquids with different viscosities.

[0030] For liquids of different viscosities, when aspirating with the same motion parameters, the pressure change detected by the pressure sensor is correlated with the liquid viscosity. The algorithm converts the pressure into viscosity to accurately determine the viscosity difference of the liquid. During the discharge process, based on the viscosity difference detected during aspiration, different motion parameters are matched for liquids of different viscosities to achieve the best pipetting effect and avoid liquid residue at the tip of the tip. This advantage is particularly obvious when pipetting micro-volumes of 2μl to 5μl.

[0031] The working process of a pipetting system consists of four parts: loading the tip, aspirating, discharging, and unloading the tip.

[0032] The tip loading process is as follows: Driven by the motion mechanism, the tip mounting column on the pipetting system of this invention can load the tip. During loading, the tip pushes the tip unloading sleeve upwards. The protruding baffle on the tip unloading sleeve acts as an optocoupler baffle, blocking the tip detection optocoupler on the optocoupler PCBA, thereby providing signal feedback to the control software. If loading is unsuccessful, such as due to inaccurate positioning or no tip being placed, no signal feedback will be received. If the control software does not receive signal feedback within a set time, it will report a loading error message, which can prevent the situation where the tip has already been installed but the user is unaware of it and the tip is reinstalled.

[0033] The liquid aspiration process is as follows: The lead screw motor drives the transmission block, which in turn drives the plunger to move away from the liquid outlet. This causes the pressure inside the body cavity to decrease. Because of the pressure difference between the plunger and atmospheric pressure, the liquid is drawn into the tip head. The displacement of the plunger can be adjusted by the control software according to the required amount of liquid to be aspirated. Simultaneously, a pressure sensor collects pressure changes during this process and converts these changes into the viscosity of the liquid.

[0034] The drainage process is as follows: Before drainage begins, the control software calculates the liquid viscosity information based on pressure changes collected during the suction process and matches the optimal motion parameters to the lead screw motor. The lead screw motor drives the transmission block, which in turn drives the plunger to move closer to the outlet, causing the internal cavity pressure to increase. Due to the pressure difference between the plunger and atmospheric pressure, the liquid is discharged from the tip. The displacement of the plunger can be adjusted by the control software according to the required amount of liquid to be drawn, allowing for either one-time suction and one-time discharge, or multiple-time suction and discharge.

[0035] The tip unloading process is as follows: Driven by the motion mechanism, the pipetting system of this invention moves to the tip unloading position, which is usually above the tip collection box. The lead screw motor drives the transmission block, which further drives the plunger to move closer to the outlet. The small displacement at the lower end is the tip unloading stroke, which is usually set to 1-5mm. During the unloading stroke, the transmission block moves from near to pushing the tip unloading column downwards. The tip unloading column pushes the tip unloading sleeve downwards, pushing the tip out of the installation position, completing the tip unloading. At the same time, the optocoupler baffle on the tip unloading sleeve disengages from the obstruction area of ​​the tip detection optocoupler on the optocoupler PCBA, triggering a feedback signal to the control software. During this process, the tip unloading column compresses the spring, and after unloading, the spring helps the tip unloading column return to its original position.

[0036] In summary, the beneficial effects of the above-mentioned technical solution of the present invention are as follows:

[0037] 1. The pipetting system of this application has a dual guide structure. The position of the tail guide ring changes with the movement of the plunger, so the effective guide length of the plunger is always a large proportion, which can maintain the coaxiality of the plunger and the internal cavity of the body and avoid the influence of misalignment.

[0038] 2. For liquids of different viscosities, this application shows that when aspirating liquid with the same motion parameters, the pressure change detected by the pressure sensor is correlated with the liquid viscosity. The algorithm converts the pressure into viscosity, thereby accurately determining the viscosity difference of the liquid. During the liquid discharge process, based on the viscosity difference detected during aspiration, different motion parameters are matched for liquids of different viscosities to achieve the best liquid transfer effect and avoid liquid residue at the tip of the tip. This advantage is particularly obvious when transferring micro-volume liquids from 2μl to 5μl. Attached Figure Description

[0039] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0041] Figure 2 This is a partial cross-sectional view of the present invention;

[0042] Figure 3 This is an exploded view of the present invention;

[0043] Figure 4 This is a flowchart of the automatic matching motion parameters of the pipetting system of the present invention;

[0044] Figure 5 This represents the relationship between viscosity and the pulse frequency for automatic matching.

[0045] The attached diagram lists the components represented by each number as follows:

[0046] 1-Screw motor, 2-Motor mounting block, 3-Base plate, 4-Transmission block, 5-Screw nut, 6-Optical coupler baffle, 7-Block, 8-Optical coupler PCBA, 9-Pressure sensor, 10-Tip unloading sleeve, 11-Plunger, 12-Sealing ring, 13-Tail guide ring, 14-Wire pressure plate, 15-Guide rail, 16-Compression spring, 17-Tip unloading post, 18-Guide ring, 19-Spring, 20-Body fixing block, 21-Body, 22-Tip mounting post, 23-Tip head. Detailed Implementation

[0047] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0049] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0050] Example 1:

[0051] like Figure 1-3 As shown, this is a preferred embodiment of the present invention, a sealing structure with variable guide length, including a lead screw motor 1, a base plate 3, a transmission block 4, a lead screw nut 5, a guide rail 15, a plunger 11, a body 21 and a tip mounting structure;

[0052] The tip installation structure includes a tip unloading sleeve 10, a tip unloading post 17, a tip installation post 22, and a tip head 23;

[0053] like Figure 3 As shown, the lead screw motor 1 is connected to the transmission block 4 via the lead screw nut 5. The transmission block 4 is mounted on the guide rail 15 and slides along the guide rail 15. The transmission block 4 is also floatingly connected to the plunger 11. A tail guide ring 13 is provided at the end of the plunger 11 away from the transmission block 4, and a sealing ring 12 is provided at the connection between the tail guide ring 13 and the plunger 11. A piston channel is formed on the inner wall of the body 21, and the plunger 11 is slidably installed inside the body 21.

[0054] A compression spring 19 is also provided between the transmission block 4 and the plunger 11. The purpose is to eliminate the backlash difference of the floating transmission.

[0055] The tail guide ring 13 changes position as the plunger 11 moves, so the effective guide length of the plunger 11 is always a large proportion, which can maintain the coaxiality of the plunger 11 and the inner cavity of the body 21 and avoid the influence of misalignment.

[0056] The base plate 3 also includes a motor mounting block 2 and a pressure plate 14. The lead screw motor 1 is mounted on the motor mounting block 2, and the track 15 is located next to the lead screw motor 1.

[0057] like Figure 2 As shown, the variable guide length sealing structure also includes a body fixing block 20, which has a through hole. The body 21 passes through the through hole and is fixed inside the body fixing block 20 by a guide ring 18. The tip unloading sleeve 10 is set at the bottom of the body fixing block 20 and wraps the part of the body 21 that passes through the body fixing block 20.

[0058] The main body fixing block 20 is equipped with a stop block 7 near the transmission block 4, and an optocoupler PCBA8 and a pressure sensor 9 are arranged on the side. The optocoupler PCBA8 has a zero position optocoupler and a tip detection optocoupler; the transmission block 4 is equipped with an optocoupler baffle 6.

[0059] The main body 21 has a through hole on its side, which is connected to the pressure sensor 9 through a capillary tube to collect pressure change data within the main body. The main body 21 also has an exhaust hole to keep the pressure in the gap between the guide ring 18 and the sealing ring consistent with the outside, thereby avoiding the influence of pressure difference caused by trapped air and improving the precision of pipetting.

[0060] The main body fixing block 20 is equipped with a tip unloading post 17, which is covered by a spring 19. The tip unloading post 17 is connected to the tip unloading sleeve 10. The spring 19 is used to keep the tip unloading post 17 facing upwards to avoid interfering with the position of the tip unloading sleeve 10. The tip unloading sleeve has a protruding baffle on one side and a contact plate on the other side. The tip unloading post and the tip unloading sleeve are connected through the contact plate.

[0061] The tip unloading sleeve 10 is connected to the tip mounting post 22 near the pipette port, and the tip head 23 is mounted on the tip mounting post 22.

[0062] Example 2:

[0063] like Figure 4 The diagram illustrates the specific steps of the pipetting system described in this application, applicable to the aforementioned variable guide length sealing structure, to achieve optimal motion parameter matching for liquid suction pressure acquisition, viscosity conversion, and liquid discharge:

[0064] S1: Before liquid aspiration, pressure sensor 9 collects atmospheric pressure AD value N1;

[0065] S2: Pressure sensor 9 collects pressure AD value N2 during liquid aspiration;

[0066] S3: Transmit the pressure AD values ​​N1 and N2 to the control software;

[0067] S4: The control software converts the difference ΔN between N1 and N2 into liquid viscosity using an algorithm;

[0068] S5: When the pipette pump performs the dispensing action, the control software automatically matches the motion parameters according to the calculation results and sends different pulse frequency signals to the lead screw motor 1; the relationship between viscosity and the automatically matched pulse frequency is as follows: Figure 5 As shown;

[0069] S6: After receiving the pulse signal, the lead screw motor 1 discharges liquid at different speeds.

[0070] It should be noted that, according to the references, there is a positive correlation between liquid viscosity and absorption pressure changes; that is, the higher the liquid viscosity, the higher the absorption pressure. The specific conversion relationship is existing technology and will not be explained in detail here. The kinematic parameters mentioned are the drainage rates obtained through actual testing and verification of liquids with different viscosities.

[0071] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principle of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A sealing structure with variable guide length, characterized in that, Includes a lead screw motor, base plate, transmission block, lead screw nut, guide rail, plunger, body, and tip mounting structure; The aforementioned tip installation structure includes a tip unload sleeve, a tip unload column, a tip installation column, and a tip header; The lead screw motor is connected to the transmission block via a lead screw nut. The transmission block is mounted on the guide rail and slides along the guide rail. The transmission block is floatingly connected to the plunger. A tail guide ring is provided at the end of the plunger away from the transmission block, and a sealing ring is provided at the connection between the tail guide ring and the plunger. A piston channel is formed on the inner wall of the main body, and the plunger is slidably installed in the main body. The tail guide ring changes position as the plunger moves to ensure the effective guiding length of the plunger. The main body has a through hole on its side, which is connected to the pressure sensor through a capillary tube; the main body also has an exhaust hole.

2. The sealing structure with variable guide length according to claim 1, characterized in that, A compression spring is also installed between the transmission block and the plunger.

3. The sealing structure with variable guide length according to claim 2, characterized in that, The sealing structure also includes a motor mounting block and a pressure plate, which are mounted on the base plate. The lead screw motor is mounted on the motor mounting block, and the track is located next to the lead screw motor.

4. A sealing structure with variable guide length according to claim 3, characterized in that, The sealing structure also includes a body fixing block, which has a through hole. The body passes through the through hole and is fixed inside the body fixing block by a guide ring. The tip unloading sleeve is set at the bottom of the body fixing block and covers the part of the body that passes through the body fixing block.

5. A sealing structure with variable guide length according to claim 4, characterized in that, The main body fixing block is equipped with a stop block near the transmission block, and an optocoupler PCBA and a pressure sensor are arranged on the side. The optocoupler PCBA has a zero-position optocoupler and a tip detection optocoupler; the transmission block is equipped with an optocoupler baffle.

6. A sealing structure with variable guide length according to claim 5, characterized in that, The main body fixing block is provided with a tip unloading post, the tip unloading post is covered with a spring, and the tip unloading post is connected to the tip unloading sleeve; the tip unloading sleeve is provided with a protruding baffle on one side and a contact plate on the other side, and the tip unloading post and the tip unloading sleeve are connected through the contact plate.

7. A sealing structure with variable guide length according to claim 6, characterized in that, The tip unloading sleeve is connected to the tip mounting post at the end near the pipette tip, and the tip head is mounted on the tip mounting post.

8. A pipetting system, applicable to the variable guide length sealing structure as described in any one of claims 1-7, for achieving optimal motion parameter matching for liquid suction pressure acquisition and viscosity conversion, and for liquid discharge, characterized in that, Includes the following steps: S1: Before liquid aspiration, the pressure sensor collects the atmospheric pressure AD value N1; S2: Pressure sensor collects pressure AD value N2 during liquid aspiration; S3: Transmit the pressure AD values ​​N1 and N2 to the control software; S4: The control software will calculate the difference between N1 and N2. The viscosity is converted into liquid viscosity using an algorithm. S5: When the pipette pump performs the dispensing action, the control software automatically matches the motion parameters according to the calculation results and sends different pulse frequency signals to the motor; S6: After receiving a pulse signal, the motor discharges liquid at different speeds.

9. A pipetting system according to claim 8, characterized in that, The aforementioned motion parameters are the drainage rates obtained through actual testing and verification of liquids with different viscosities.

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