High-precision micropipetting device and control method thereof

Abstract

The invention relates to a high-precision micro-pipetting device and a control method thereof, and the pipetting device, the high-precision micro-pipetting device comprises a control module, a positive pressure system, a negative pressure system, a three-way solenoid valve and a pipetting head, the control module controls the switching of the three-way solenoid valve to enable a micro-control solenoid valve to be communicated with the positive pressure system or the negative pressure system, and the control module controls the opening time of the micro-control solenoid valve; a proportional valve, a pressure sensor and a flow sensor are arranged between the three-way electromagnetic valve and the micro-control electromagnetic valve, the proportional valve is used for adjusting the pressure and the flow of a gas circuit, and the control module conducts PID control on the proportional valve according to measurement data of the pressure sensor and the flow sensor. The positive / negative pressure value and the gas flow rate of the gas circuit are adjusted through the proportional valve, so that the positive / negative pressure at the liquid suction head can be changed, the suction and discharge of samples with different viscosities can be realized, the switching time of the liquid suction head is controlled through the micro-control electromagnetic valve, and the sample amount of each time of pipetting can be accurately controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of experimental analysis instruments, and particularly relates to a high-precision micro pipetting device and a control method thereof. Background Art

[0002] A pipette is a metering tool that transfers liquid from an original container to another container within a certain range of measuring ranges, and is widely used in fields such as biology and chemistry. An air displacement pipette can accurately dispense aqueous solutions, and the use of low-cost disposable tips effectively reduces the risk of cross-contamination, and is widely used in fields such as biochemical experiments, environmental monitoring, and food safety detection.

[0003] However, when pipetting a colloid with a certain viscosity, the existing pipetting devices are difficult to accurately control the liquid volume of each pipetting, thus affecting the accuracy and repeatability of the experiment; and due to the limited volume of the piston chamber of the existing pipetting devices, it is impossible to completely discharge the colloid in the tip, resulting in waste of reagents and increased costs.

[0004] Based on the above technical problems, the present application proposes a high-precision micro pipetting device and a control method thereof. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-precision micro pipetting device and a control method thereof to solve the technical problems mentioned in the background art. The purpose of the present invention is achieved through the following technical solutions: A high-precision micro pipetting device includes a control module, a positive pressure system, a negative pressure system, a three-way solenoid valve, and a pipette tip. The positive pressure system and the negative pressure system are respectively connected to two medium inlets of the three-way solenoid valve. The pipette tip is connected to the medium outlet of the three-way solenoid valve through a micro-control solenoid valve. The three-way solenoid valve and the micro-control solenoid valve are both electrically connected to the control module. The control module controls the three-way solenoid valve to switch so that the micro-control solenoid valve is connected to the positive pressure system or the negative pressure system, and the control module controls the opening time of the micro-control solenoid valve. A proportional valve, a pressure sensor, and a flow sensor are respectively arranged between the three-way solenoid valve and the micro-control solenoid valve. The pressure sensor and the flow sensor are both located downstream of the proportional valve. The proportional valve, the pressure sensor, and the flow sensor are all electrically connected to the control module. The proportional valve is used to adjust the pressure and flow of the gas path, and the control module performs PID control on the proportional valve according to the measurement data of the pressure sensor and the flow sensor.

[0006] Further, a manifold is arranged between the pressure sensor and the flow sensor. The manifold is provided with a plurality of channels. The number of pipette tips and micro-control solenoid valves is equal to the number of channels. The pipette tips are respectively connected to the channels through the micro-control solenoid valves one by one.

[0007] Further, the positive pressure system includes an air pump, a positive pressure tank, and a filter pressure reducing valve. The filter pressure reducing valve is connected to the air pump through the positive pressure tank, and the filter pressure reducing valve is connected to any one of the medium inlets of the three-way solenoid valve.

[0008] Further, the negative pressure system includes a throttle valve, a vacuum generator, and a negative pressure tank. The vacuum generator is connected to the filter pressure reducing valve through the throttle valve. The air extraction port of the negative pressure tank is connected to the vacuum generator, and the air inlet of the negative pressure tank is connected to the other medium inlet of the three-way solenoid valve.

[0009] Further, a flow switch is installed downstream of the proportional valve.

[0010] Further, a disposable pipette tip is detachably installed at the liquid suction head.

[0011] A control method for any one of the above high-precision micro pipetting devices includes the following steps: Step S1: Obtain the viscosity coefficient of the sample, and set the positive pressure, negative pressure, and air flow rate according to the viscosity coefficient of the sample; Step S2: The control module controls the three-way solenoid valve to act, so that the negative pressure system is connected to the micro control solenoid valve. The micro control solenoid valve is opened for t1 and then closed, so that a negative pressure is generated at the liquid suction head to suck the sample; Step S3: The control module controls the three-way solenoid valve to act, so that the positive pressure system is connected to the micro control solenoid valve. The micro control solenoid valve is opened for t2 and then closed, so that a positive pressure is generated at the liquid suction head to eject the sample.

[0012] Further, when the viscosity coefficient of the sample is 1 - 50 mPa·s, the positive pressure is 50 - 100 kPa, the negative pressure is -50 kPa, and the air flow rate is 5 - 10 L / min; when the viscosity coefficient of the sample is 50 - 100 mPa·s, the positive pressure is 100 - 200 kPa, the negative pressure is -80 kPa, and the air flow rate is 10 - 20 L / min; when the viscosity coefficient of the sample is 100 - 200 mPa·s, the positive pressure is 300 kPa ± 5%, the negative pressure is -100 kPa, and the air flow rate is 20 - 50 L / min.

[0013] Further, t1 is 10 ms - 100 ms, and t1 is calibrated and determined by the weighing method.

[0014] Further, t2 is 10 ms - 100 ms.

[0015] The technical solution provided by the embodiment of the present application has at least the following technical effects or advantages: 1. By adjusting the positive / negative pressure value and air flow rate of the air circuit through the proportional valve, the positive / negative pressure at the liquid suction head can be changed, and the suction and discharge of samples with different viscosities can be realized, improving the application range of the pipetting device; 2. By adjusting the positive / negative pressure values and air flow rate of the gas path through a proportional valve, and controlling the opening and closing time of the pipette tip through a micro-controlled solenoid valve, the sample volume of each pipetting can be accurately controlled, ensuring the accuracy and repeatability of the experiment; 3. By providing the power for liquid aspiration and drainage to the pipette tip through a positive / negative pressure system, the volume limitation of the traditional piston-type pipetting device is broken through. It can ensure that the sample is completely discharged from the pipette tip, avoiding waste of reagents caused by sample residue, and saving costs. Brief Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic diagram of the structure of an embodiment of the present application.

[0018] Reference numerals: 1, positive pressure system; 2, filter pressure reducing valve; 3, negative pressure system; 4, three-way solenoid valve; 5, proportional valve; 6, flow switch; 7, pressure sensor; 8, flow sensor; 9, micro-controlled solenoid valve; 10, pipette tip. Detailed Embodiments

[0019] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following will, in conjunction with the accompanying drawings and preferred embodiments, detail the specific embodiments, structures, features and their effects of the present invention as follows.

[0020] Embodiment 1 As Figure 1 shown, a high-precision micro-pipetting device includes a control module (not shown), a positive pressure system 1, a filter pressure reducing valve 2, a negative pressure system 3, a three-way solenoid valve 4, a proportional valve 5, a pressure sensor 7, a flow sensor 8, a micro-controlled solenoid valve 9 and a pipette tip 10. The three-way solenoid valve 4 is a two-in-one-out three-way solenoid valve. The positive pressure system 1 is connected to a medium inlet of the three-way solenoid valve 4 through the filter pressure reducing valve 2, and the negative pressure system 3 is communicated with the other medium inlet of the three-way solenoid valve 4.

[0021] Specifically, the positive pressure system 1 includes an air pump and a positive pressure tank. The air inlet of the positive pressure tank is connected to the air outlet of the air pump, the air outlet of the positive pressure tank is connected to the filter pressure reducing valve 2, and the air outlet of the filter pressure reducing valve 2 is communicated with a medium inlet of the three-way solenoid valve 4 through a three-way joint. When in use, the air pump sends the compressed air into the positive pressure tank, and after being filtered and pressure-regulated by the filter pressure reducing valve 2, it is transported to the three-way solenoid valve 4.

[0022] The negative pressure system 3 includes a throttle valve, a vacuum generator, and a negative pressure tank. The vacuum generator is connected to the air outlet of the filter pressure reducing valve 2 through a tee joint. The throttle valve is installed between the tee joint and the vacuum generator. The air suction port of the negative pressure tank is connected to the vacuum generator, and the air inlet of the negative pressure tank is connected to the other medium inlet of the three-way solenoid valve 4. During use, high-pressure air is introduced into the vacuum generator through the throttle valve, thereby creating a negative pressure in the negative pressure tank.

[0023] As shown in Figure 1 the figure, the proportional valve 5, the pressure sensor 7, the flow sensor 8, the micro-controlled solenoid valve 9, and the liquid suction head 10 are sequentially installed at the medium outlet of the three-way solenoid valve 4. A disposable tip is detachably installed at the liquid suction head 10 to avoid cross-contamination and ensure the accuracy of the experiment. The three-way solenoid valve 4 is electrically connected to the control module, and the control module controls the three-way solenoid valve 4 to switch so that the liquid suction head 10 is respectively connected to the positive pressure system 1 or the negative pressure system 3. When the liquid suction head 10 is connected to the negative pressure system 3, the negative pressure system 3 provides a negative pressure at the liquid suction head 10 for sucking the sample into the liquid suction head 10; when the liquid suction head 10 is connected to the positive pressure system 1, the positive pressure system 1 provides a positive pressure at the liquid suction head 10 for discharging the sample in the liquid suction head 10.

[0024] The proportional valve 5, the pressure sensor 7, and the flow sensor 8 are all electrically connected to the control module. The proportional valve 5 is used to adjust the pressure and flow rate of the gas path. The control module performs PID control on the proportional valve 5 according to the measurement data of the pressure sensor 7 and the flow sensor 8 to improve the accuracy and stability of pressure control and flow control. When the gas path pressure is high, the opening degree of the proportional valve 5 is increased; when the gas path pressure is low, the opening degree of the proportional valve 5 is decreased until the pipeline pressure fluctuation tends to be stable.

[0025] The micro-controlled solenoid valve 9 is electrically connected to the control module. The control module controls the opening time of the micro-controlled solenoid valve 9. The longer the opening time of the micro-controlled solenoid valve 9, the greater the flow rate of the positive / negative pressure gas flowing through the liquid suction head 10, and the more the sample volume sucked / discharged.

[0026] Among them, a flow switch 6 is also installed between the proportional valve 5 and the pressure sensor 7. The flow switch 6 is used to monitor the gas path flow rate. When the gas path flow rate is higher or lower than the set threshold, the device is automatically shut down to ensure the safety of the pipetting device.

[0027] As a preferred embodiment of the present application, a manifold is also installed between the pressure sensor 7 and the flow sensor 8. Eight channels are opened on the manifold. The number of the micro-controlled solenoid valves 9 and the liquid suction heads 10 are both eight. Each liquid suction head 10 is respectively connected to a channel through a micro-controlled solenoid valve 9, so that multi-channel pipetting can be realized.

[0028] Embodiment 2 A control method for a high-precision micro pipetting device in Embodiment 1, comprising the following steps: Step S1: Obtain the viscosity coefficient of the sample, and set the positive pressure, negative pressure, and air flow rate according to the viscosity coefficient of the sample; Wherein, when the viscosity coefficient of the sample is 1 - 50 mPa·s, the positive pressure is 50 - 100 kPa, the negative pressure is -50 kPa, and the air flow rate is 5 - 10 L / min; when the viscosity coefficient of the sample is 50 - 100 mPa·s, the positive pressure is 100 - 200 kPa, the negative pressure is -80 kPa, and the air flow rate is 10 - 20 L / min; when the viscosity coefficient of the sample is 100 - 200 mPa·s, the positive pressure is 300 kPa ± 5%, the negative pressure is -100 kPa, and the air flow rate is 20 - 50 L / min.

[0029] Step S2: The control module controls the three-way solenoid valve to act, so that the negative pressure system is connected to the micro-control solenoid valve. The micro-control solenoid valve is opened for t1 and then closed, so that a negative pressure is generated at the liquid suction head to suck the sample; Specifically, first move the liquid suction head to the original container and make the liquid suction head extend into the sample to be moved. Then, the control module controls the three-way solenoid valve 4 to act, so that the negative pressure system 3 is connected to the micro-control solenoid valve 9. The negative pressure of the negative pressure system 3 is finely adjusted by the proportional valve 5 and then input into the micro-control solenoid valve 9. Finally, the micro-control solenoid valve 9 is opened for t1 and then closed, so that a negative pressure is generated at the liquid suction head to suck the sample.

[0030] Wherein, t1 is 10 ms - 100 ms, and t1 is calibrated and determined by the weighing method, that is, different t1 times are preset, and the sample after suction is weighed, so as to obtain the sample volume sucked at different t1. Finally, t1 is determined according to the required sample volume to be sucked. The larger t1 is, the more sample is sucked.

[0031] Step S3: The control module controls the three-way solenoid valve to act, so that the positive pressure system is connected to the micro-control solenoid valve. The micro-control solenoid valve is opened for t2 and then closed, so that a positive pressure is generated at the liquid suction head to eject the sample.

[0032] Specifically, first move the liquid suction head 9 with the sucked sample to the new container. Then, the control module controls the three-way solenoid valve 4 to act, so that the positive pressure system 1 is connected to the micro-control solenoid valve 9. The positive pressure of the positive pressure system 1 is finely adjusted by the proportional valve 5 and then input into the micro-control solenoid valve 9. Finally, the micro-control solenoid valve 9 is opened for t2 and then closed, so that a positive pressure is generated at the liquid suction head 9 to discharge the sample.

[0033] Wherein, t2 is 10 ms - 100 ms, and t2 is calibrated and determined by the weighing method, that is, different t2 times are preset, and the liquid suction head after discharge is weighed, so as to obtain the sample volume discharged at different t2. Finally, t2 is determined according to the required sample volume to be discharged. The larger t2 is, the more sample is discharged.

[0034] The technical solution provided by the embodiments of the present application has at least the following technical effects or advantages: 1. By adjusting the positive / negative pressure values and air flow rates of the air circuit through a proportional valve, the positive / negative pressure at the liquid suction head can be changed, enabling the aspiration and discharge of samples with different viscosities, and improving the applicable range of the pipetting device. 2. By adjusting the positive / negative pressure values and air flow rates of the air circuit through a proportional valve and controlling the opening and closing time of the liquid suction head through a micro-controlled solenoid valve, the sample volume for each pipetting can be accurately controlled, ensuring the accuracy and repeatability of the experiment. 3. By providing the power for liquid suction and discharge to the pipetting head through a positive / negative pressure system, the volume limitation of the traditional piston-type pipetting device is broken through, ensuring that the sample can be completely discharged from the liquid suction head, avoiding waste of reagents caused by sample residue, and saving costs.

[0035] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to form equivalent embodiments with equivalent changes. However, as long as the technical content of the present invention is not departed from, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high-precision micro pipetting device, characterized in that, It includes a control module, a positive pressure system, a negative pressure system, a three-way solenoid valve, and a liquid suction head. The positive pressure system and the negative pressure system are respectively connected to two medium inlets of the three-way solenoid valve. The liquid suction head is connected to the medium outlet of the three-way solenoid valve through a micro-control solenoid valve. The three-way solenoid valve and the micro-control solenoid valve are both electrically connected to the control module. The control module controls the three-way solenoid valve to switch so that the micro-control solenoid valve is connected to the positive pressure system or the negative pressure system, and the control module controls the opening time of the micro-control solenoid valve. A proportional valve, a pressure sensor, and a flow sensor are respectively arranged between the three-way solenoid valve and the micro-control solenoid valve. The pressure sensor and the flow sensor are both located downstream of the proportional valve. The proportional valve, the pressure sensor, and the flow sensor are all electrically connected to the control module. The proportional valve is used to adjust the pressure and flow rate of the gas path. The control module performs PID control on the proportional valve according to the measurement data of the pressure sensor and the flow sensor.

2. The high-precision micro pipetting device according to claim 1, wherein, A manifold is arranged between the pressure sensor and the flow sensor. The manifold is provided with a plurality of channels. The number of the liquid suction heads and the number of the micro-control solenoid valves are both equal to the number of the channels. The liquid suction heads are respectively connected to the channels through the micro-control solenoid valves one by one.

3. A high-precision micro pipetting device according to claim 1, characterized in that, The positive pressure system includes an air pump, a positive pressure tank, and a filter pressure reducing valve. The filter pressure reducing valve is connected to the air pump through the positive pressure tank. The filter pressure reducing valve is connected to any one of the medium inlets of the three-way solenoid valve.

4. A high-precision micro pipetting device according to claim 3, characterized in that, The negative pressure system includes a throttle valve, a vacuum generator, and a negative pressure tank. The vacuum generator is connected to the filter pressure reducing valve through the throttle valve. The air extraction port of the negative pressure tank is connected to the vacuum generator. The air inlet of the negative pressure tank is connected to the other medium inlet of the three-way solenoid valve.

5. A high-precision micro pipetting device according to claim 1, characterized in that, A flow switch is installed downstream of the proportional valve.

6. The high-precision micro pipetting device according to claim 1, characterized in that, A disposable tip is detachably installed at the liquid suction head.

7. A control method for the high-precision micro pipetting device according to any one of claims 1-6, characterized in that, It includes the following steps: Step S1: Obtain the viscosity coefficient of the sample, and set the positive pressure, negative pressure, and air flow rate according to the viscosity coefficient of the sample. Step S2: The control module controls the three-way solenoid valve to act so that the negative pressure system is connected to the micro-control solenoid valve. The micro-control solenoid valve is opened for t1 and then closed to generate negative pressure at the liquid suction head to suck the sample. Step S3: The control module controls the three-way solenoid valve to act so that the positive pressure system is connected to the micro-control solenoid valve. The micro-control solenoid valve is opened for t2 and then closed to generate positive pressure at the liquid suction head to eject the sample.

8. The control method of a high-precision micro pipetting device according to claim 7, characterized in that, When the viscosity coefficient of the sample is 1 - 50 mPa·s, the positive pressure is 50 - 100 kPa, the negative pressure is -50 kPa, and the air flow rate is 5 - 10 L / min; when the viscosity coefficient of the sample is 50 - 100 mPa·s, the positive pressure is 100 - 200 kPa, the negative pressure is -80 kPa, and the air flow rate is 10 - 20 L / min; when the viscosity coefficient of the sample is 100 - 200 mPa·s, the positive pressure is 300 kPa ± 5%, the negative pressure is -100 kPa, and the air flow rate is 20 - 50 L / min.

9. The control method of a high-precision micro pipetting device according to claim 7, characterized in that, The t1 is 10 ms - 100 ms, and the t1 is determined by calibration through the weighing method.

10. The control method of a high-precision micro pipetting device according to claim 7, characterized in that, The t2 is 10 ms - 100 ms.

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