CN117138859A - Pipetting control method and application of pneumatic pipetting pump - Google Patents

Abstract

The invention relates to a pipetting control method of a pneumatic pipetting pump, and belongs to the technical field of automatic pipetting equipment. The pipetting control method comprises a liquid level detection step, wherein the liquid level detection step comprises the following steps: s1: starting an air pressure real-time acquisition system to acquire an air pressure value in a piston cylinder of the liquid transfer pump; s2: controlling the liquid transfer pump to move towards the liquid level, and simultaneously controlling the piston in the liquid transfer pump to move towards the liquid level according to a preset speed, so that the piston cylinder generates air flow which is continuously blown outwards; s3: when the air pressure sensor in the liquid transfer pump collects that the variation difference value of the amplitude variation of the air pressure waveform is larger than the preset liquid level triggering threshold value, the liquid level is judged to be contacted and detected. The control method is based on the air pressure feedback control pipetting process, can flexibly identify the liquid level and accurately acquire the position information of the liquid object, and compared with the conventional air pressure type detection, the control method has the advantages of high air pressure detection response speed, high air pressure detection sensitivity and high flexible adjustment.

Description

Pipetting control method and application of pneumatic pipetting pump

Technical Field

The invention relates to the technical field of automatic pipetting equipment, in particular to a pipetting control method and application of a pneumatic pipetting pump.

Background

With the rapid development of science and technology, laboratory such as biology, chemistry, environment, medicine research and development, food and the like and unit pipetting work such as hospitals, disease control, blood stations and the like enter into standardization, an automatic pipetting system (or pipetting workstation) in the market becomes gradually popular in the face of more complex study objects and increasing sample numbers, and pipetting transfer positions and pipetting process quality in the pipetting workstation determine pipetting accuracy and experimental timeliness, wherein a pneumatic liquid level detection and pipetting process quality monitoring system is the most important link of pipetting working equipment and is a set of most efficient and complex methodology system requiring stable accuracy.

However, due to the limitation of the technology, the traditional liquid level fixing liquid transfer mode needs to completely go deep to a fixed or unknown position below the liquid level to perform liquid transfer operation, so that the defects of liquid quality loss and inaccurate actual liquid transfer amount exist, and the accuracy of experiments is affected.

Based on this, various techniques have been adopted to detect the liquid level during pipetting, such as the air pressure type liquid level detection method and apparatus disclosed in CN112473760a, which detect the liquid level position by utilizing the change of air pressure in contact with the liquid level. Meanwhile, there is a pneumatic pipette disclosed in CN215087261U, which can accurately judge whether the suction head is contacted with the liquid level by detecting the air pressure value in the air cylinder and the external air pressure value and comparing the air pressure difference between the air pressure value and the external air pressure value, so that the problems that the repeated air discharge and air suction adopted in the prior art cause liquid aspiration pollution are avoided, the air in the air cylinder needs to be emptied after air suction, and the reagent is blown out of a test tube during air blowing and the like are solved.

However, the above solutions have the problems that the pressure in the cavity can be changed only by contacting the liquid surface, even immersing the cavity below the liquid surface, and the pressure in the cavity is slow to change and react, which results in longer detection time.

In order to rapidly and sensitively detect the liquid level, a liquid transfer pump disclosed in CN115069322A is further included, a dual detection system of an air pressure detection system and a capacitance detection system is adopted for detection, and a conductive suction head is contacted with a solution to be sampled to generate a capacitance signal, so that the conductive suction head is judged to reach the liquid level of the solution to be sampled. However, such a transfer pump requires a conductive shampoo, so that the consumable cost is greatly increased, and the stability and precision of the capacitive detection system are affected by the fact that the capacitive characteristics are easily interfered by magnetic fields of surrounding environments, so that the technical popularization is adversely affected.

Disclosure of Invention

Based on the above, it is necessary to provide a pipetting control method of a pneumatic pipetting pump for solving the problems of low detection precision, certain delay or higher cost of the automatic pipetting device, wherein the control method is based on pneumatic feedback control pipetting process, can flexibly identify liquid level and accurately acquire the position information of a liquid object.

A pipetting control method of a pneumatic pipetting pump, comprising a liquid level detection step comprising:

s1: starting an air pressure real-time acquisition system to acquire an air pressure value in a piston cylinder of the liquid transfer pump;

s2: controlling the liquid transfer pump to move towards the liquid level, and simultaneously controlling the piston in the liquid transfer pump to move towards the liquid level according to a preset speed, so that the piston cylinder generates air flow which is continuously blown outwards;

s3: when the air pressure sensor in the liquid transfer pump collects that the variation difference value of the amplitude variation of the air pressure waveform is larger than the preset liquid level triggering threshold value, the liquid level is judged to be contacted and detected.

The inventor finds in earlier research that in the conventional technology, the air pressure in the cavity of the piston cylinder can be changed slowly only by the contact of the gun head with the liquid surface and even immersion below the liquid surface, and the air pressure in the cavity is changed slowly, so that the detection time is longer, the difficulty is also increased in designing the length of the air duct connecting the air pressure sensor and the piston cylinder, because the longer the air duct is, the more slowly the reaction is, and the acquired liquid surface position is not accurate enough. Meanwhile, the position of the liquid level can be detected after the gun head is immersed below the liquid level, so that the problem that the gun head is stained with liquid in the liquid level detection process is solved, and the risk of pollution and liquid waste can be brought to subsequent procedures.

The liquid transferring control method of the pneumatic liquid transferring pump controls the liquid transferring pump to move towards the liquid level, and simultaneously controls the piston in the liquid transferring pump to move towards the liquid level according to the preset speed, so that the air flow continuously blown outwards (towards the liquid level) is generated in the cavity of the piston cylinder.

The method is very sensitive to the air pressure change reaction, can identify only when touching the liquid level, can identify without immersing the liquid level at a specific height, and solves the design problem that the length of the air duct needs to be considered. Meanwhile, in practical application, the requirements on the size and the moving speed of the air flow are low, for example, the liquid level can be sensitively identified by controlling the piston at the slow speed of 2mm/s, and the control method does not need fixed amplitude and frequency and can improve the sensitivity only by specific positive acceleration-related characteristics, unlike a blowing-sucking type pneumatic liquid level detection method. And judging whether the liquid level is contacted by adopting the air pressure variation, namely a front-back difference value, rather than the air pressure variation reaching a certain absolute value. In consideration of the fact that the air pressure value tends to dynamically change in different environments in the actual application process, the difference value before and after the change is monitored in the control method, so that the air pressure value does not need to be considered to reach a certain air pressure value high-point or low-point range, the risk or problem of misjudgment caused by the air pressure interference by the environment is greatly improved, the design principle also provides the stability of the detection method, and finally detected liquid level is more accurate.

In one embodiment, in step S2, the piston in the liquid transfer pump is controlled to move upward by a preset distance, and then moves toward the liquid level at a preset speed. The piston moves upwards for a certain distance and then downwards, so that stable outwards blown air flow is formed, a reverse (inwards) air flow is formed rapidly after the piston contacts the liquid level, the reflecting time of detecting the liquid level is improved, the instantaneous air pressure change difference of the liquid level is large, the accuracy and stability of liquid level detection and discrimination are improved, and the liquid level can not be contacted by mistake. After the liquid level is detected, the piston quickly returns to the original position.

In one embodiment, in step S2, the initial position of the liquid transfer pump is taken as an origin, the distance between the contact position of the liquid level detected by the liquid transfer pump and the origin is taken as a descending height, the depth of the liquid to be transferred is calculated by the distance between the bottom of the container containing the liquid to be transferred and the origin, and the liquid volume to be transferred is calculated by combining the shape of the container.

By using the method, whether the residual capacity of the container meets the target transfer requirement can be identified, the liquid depth is obtained by comparing the obtained descending height with the distance between the bottom of the container and the origin, which is obtained in advance, the residual volume is calculated by combining the shape of the container, the result that the liquid amount is enough or insufficient is identified, and the phenomenon that empty detection or empty suction is easy to occur when only a small amount of samples are used is overcome. For example: using a cylindrical vessel with radius r, the remaining liquid volume v=pi r2x, x=the distance between the bottom of the vessel and the origin-the drop height.

In one embodiment, in step S3, the air pressure waveform amplitude is subjected to the following filtering process: and acquiring air pressure values at preset time points, sorting the air pressure values according to the air pressure values after acquiring the air pressure values at a plurality of time points, removing a plurality of air pressure values before and after sorting, and carrying out average value processing on the rest air pressure values to be used as a change difference value for judging the change of the amplitude of the air pressure waveform. In the filtering treatment, the highest value sequenced at the head and the tail is removed after sequencing, so that the defect of random interference in an arithmetic average filtering method is overcome, the filtering method is simple and high in efficiency, the judgment value is more reliable and stable through the filtering treatment mode, and the risk of misjudgment is avoided.

In one embodiment, in step S3, the air pressure waveform amplitude is subjected to the following filtering process: and acquiring air pressure values at time points with an interval of 100+/-20 mu s, sorting the air pressure values according to the air pressure values after acquiring the air pressure values at 30+/-10 time points, removing the air pressure values which are 5+/-3 before and 5+/-3 after sorting, and carrying out average value processing on the rest air pressure values to be used as a change difference value for judging the change of the amplitude of the air pressure waveform.

In one embodiment, the liquid level trigger threshold is set according to the percentage of the change rate of the air pressure waveform amplitude acquired by the air pressure sensor on the reference amplitude (the base value before imbibition), and when the percentage change difference is larger than the preset liquid level trigger threshold, the contact with the liquid level is judged.

In one embodiment, the pipetting control method of the pneumatic pipetting pump further comprises a pipetting step, wherein the pipetting step comprises the following steps:

s4: and controlling a piston in the liquid transfer pump to carry out liquid suction, and simultaneously controlling the liquid transfer pump to move downwards along with the descending of the liquid level, so that the depth of the gun head immersed in the liquid level is kept within a preset range.

Through the mode of the liquid level following, the liquid gun head is moved in the liquid suction process to always keep a certain immersed liquid level to follow the liquid level to descend, and the liquid level following function solves the problem caused by the fact that the liquid suction is empty or the gun head stretches into the liquid level too much under the condition of fixing the liquid level liquid suction height.

In one embodiment, the method for controlling the pipetting of the pneumatic pipetting pump further includes a pipetting quality monitoring step, the pipetting quality monitoring step is performed along with the pipetting step, and the pipetting quality monitoring step includes: suction monitoring, bubble monitoring and blockage monitoring;

the suction monitoring comprises the following steps: comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging as suction when the variation difference of the amplitude variation of the air pressure waveform is smaller than the variation difference of the amplitude variation of a preset suction waveform in the pipetting process;

the occlusion monitoring comprises the steps of: comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging that the air pressure value waveform is blocked when the air pressure value waveform variation amplitude is larger than the preset normal waveform variation amplitude difference value and the air pressure value waveform is in a low-pressure state continuously in the pipetting process;

the bubble monitoring comprises the following steps: comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging as a suction bubble when the air pressure value waveform variation amplitude is between a preset normal waveform variation amplitude difference value and a preset suction air waveform variation amplitude difference value in the pipetting process;

the normal waveform variation amplitude difference is larger than the suction waveform variation amplitude difference.

It can be appreciated that the normal pipetting waveform and the pipetting waveform can be determined by debugging through preliminary experiments. Through the variation difference of the air pressure, whether the pipetting process has the accidents of suction, air bubbles and blockage can be detected in real time, so that intelligent monitoring is realized, and the unmanned automatic operation is realized.

In one embodiment, after the liquid absorbing step is completed, the liquid drop preventing step further comprises:

s5: and monitoring the collected air pressure value in real time to finish the air pressure value in the process of imbibition as an anti-drop initial value, and controlling the piston to move upwards to return to the imbibition body when the waveform amplitude of the air pressure value changes beyond a threshold value, so that the air pressure value returns to the range of the anti-drop initial value.

In the conventional technology, after the pipetting is completed, the liquid is usually directly sucked up for a trace stroke, that is, a part of air is sucked up and remains at the tip of the gun head, so that the method is a method for preventing the liquid drops from dripping. However, according to the difference of application scenes and the difference of air tightness, for example, the time for a pump to stand in a space after sucking liquid is long, or the liquid drops can drop again when the air tightness is poor. The conventional pipetting device has the common problem of air tightness, the pipetting device using the same pipetting gun head has inconsistent air tightness, and the situation of fixed micro-stroke is difficult to set.

It can be understood that the control precision of the liquid drops is required to be higher in the fields of biology, medicine and the like, and the liquid-transferring control quantity of 1 mu l level can be achieved when liquid is separated after liquid is absorbed, so that according to practical application scenes, such as 1000 mu l, 200 mu l and 10 mu l of liquid-transferring gun heads with larger differences and different specifications, the formed liquid drops are also larger in volume and weight and unsuitable for fixed stroke compensation.

Meanwhile, a basic threshold is set to enable the basic threshold to exceed a preset threshold for compensation, so that the pump is prevented from frequently performing compensation actions, and the service life of equipment is prolonged.

The pipetting control method of the pneumatic pipetting pump further comprises a pipetting step, wherein the pipetting step comprises the following steps of:

s6: and controlling a piston in the liquid transferring pump to separate liquid, and simultaneously controlling the liquid transferring pump to move upwards along with the rising of the liquid level, so that the distance between the gun head and the liquid level is kept within a preset range.

Through the mode that above-mentioned liquid level follows, move liquid rifle head in the imbibition in-process and follow the liquid level with keeping having certain height all the time and rise along the liquid level, solved in the liquid in-process liquid and be stained with the problem that the rifle head outer wall leads to the result inaccurate easily.

The invention also discloses a pneumatic liquid transfer pump, which comprises: the pipetting control system adopts the control method to finish pipetting operation.

In one embodiment, the liquid transferring pump assembly comprises a liquid transferring pump, a driving device and a position sensing device, the liquid transferring control system sends out an instruction to control the driving device to drive the liquid transferring pump and the piston therein to move after analysis and judgment are carried out according to the collected air pressure value in the piston cylinder of the liquid transferring pump, and when the liquid transferring pump is located at the initial position, the position sensing device is triggered to send out a signal.

It can be appreciated that the specific structure of the pneumatic liquid transfer pump can adopt conventional pneumatic liquid transfer equipment, and only the functions of monitoring the air pressure in the piston cavity in real time, coordinating and controlling the lifting of the liquid transfer pump and the movement of the piston to finish sucking and blowing are ensured.

Compared with the prior art, the invention has the following beneficial effects:

the liquid transfer control method of the pneumatic liquid transfer pump provided by the invention is based on pneumatic liquid level detection, can flexibly identify the liquid level and accurately acquire the liquid level position information, and has the characteristics of high response speed of liquid level detection and high sensitivity of pneumatic detection.

Compared with capacitive liquid level detection, the pneumatic liquid level detection has the characteristic of low cost, does not have conductive requirements on the hair washing gun head used for liquid transfer, is applicable to materials with conductive characteristics or nonconductive characteristics, and greatly reduces the cost of consumable materials.

And the invention can also be based on the air pressure detection, carry the pipetting quality monitoring system, form a complete system of whole process from beginning pipetting to pipetting and finishing, in order to guarantee the pipetting position, guarantee the accuracy of pipetting quality. The pipetting quality monitoring method can identify the faults and interferences in the pipetting process, including the pipetting empty suction interference, the bubble interference, the blockage interference and the like, and can avoid the cross contamination or interference in the pipetting process by a liquid drop anti-dripping flow.

Drawings

Fig. 1 is a flow chart of a pipetting control method of a pneumatic pipetting pump.

Fig. 2 is a schematic diagram of a normal pipetting waveform obtained by monitoring air pressure.

Fig. 3 is a flow chart of the fluid level detection operation.

Fig. 4 is a pipetting quality monitoring workflow diagram.

Fig. 5 is a schematic diagram of waveforms of air pressure values collected under different conditions.

Fig. 6 is a workflow diagram of a drop prevention step.

Fig. 7 is a schematic diagram of an air pressure waveform of the drop prevention control process.

Detailed Description

In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, 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 invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

Examples

A pipetting control method of a pneumatic pipetting pump is shown in figure 1, and comprises the steps of liquid level detection, pipetting, drop prevention, pipetting separation and the like, and pipetting quality monitoring is carried out in the pipetting process, so that pipetting accuracy and stability are improved, and risks of pollution, pipetting errors, failures and the like are reduced.

It can be appreciated that the pipetting control method of the pneumatic pipetting pump of the embodiment can be realized by means of equipment comprising a pipetting pump assembly and a pipetting control system, and the pipetting control system can acquire and obtain the air pressure value in a pipetting pump piston cylinder only by requiring the pipetting pump assembly to comprise a pipetting pump, a driving device and a position sensing device, and the driving device can drive the pipetting pump and the piston therein to move according to the instruction of the pipetting control system.

For the normal pipetting process, the monitored normal pipetting waveform curve is shown in fig. 2, wherein the line segment marked 1 represents the pre-pipetting stage, and A is the liquid level detection starting point; the line segment of the mark 2 represents the liquid level detection process; b is the liquid level detection completion point; c is a liquid transfer (imbibition) starting point, and a bubble, suction and blockage monitoring starting point; the line segment of the mark 3 represents a pipetting process, and pipetting operation and pipetting quality monitoring operation are carried out in the pipetting process; d is a liquid transfer completion point, and a bubble, suction and blockage monitoring end point; e is a monitoring starting point of the drop prevention process; the line segment denoted by 4 represents the holding process after the completion of pipetting, which performs the drop prevention operation.

The pipetting control method of the invention is described below in connection with a specific application scenario, but it can be understood that the following process flow can be flexibly adjusted according to the equipment requirements and the detection conditions.

First, liquid level detection is performed, and the operation flow thereof is shown in fig. 3.

S1: and starting the air pressure real-time acquisition system to acquire the air pressure value in the piston cylinder of the liquid transfer pump.

When equipment is started and a pipetting procedure is carried out, an air pressure acquisition chip arranged in a pipetting pump is initialized, liquid level detection parameter adaptation is carried out, meanwhile, software obtains a current air pressure value as a reference value for analysis and judgment such as pipetting process monitoring, air bubble monitoring, blockage monitoring and the like, and the acquisition system is kept to acquire and monitor the air pressure value in a pipetting pump piston cylinder in real time.

In this embodiment, parameters for performing parameter adaptation include: maximum travel and speed of the liquid transfer pump in the vertical direction, a liquid level trigger threshold value of the detected liquid level, liquid level detection sensitivity and liquid level following speed.

It can be understood that the liquid level detection sensitivity refers to the reaction speed when contacting the liquid level in the liquid level detection process, and is the variation amplitude of the air pressure when contacting the liquid level under the same environment and method, and the air pressure can be realized by setting and adjusting the gain parameters of the air pressure sensor, and the gains of 1 time, 2 times, 4 times and 16 times can be respectively adjusted. For example, the air pressure value before detection is 1000, the air pressure value under the condition of sensitivity A (1-time gain) is changed from 1000 to 1200, the liquid level is judged to be detected, and the air pressure value under the condition of sensitivity B (2-time gain) is changed from 1000 to 1400, the liquid level is judged to be detected.

S2: the liquid transferring pump is controlled to move towards the liquid level (namely downwards), and meanwhile, the piston in the liquid transferring pump is controlled to move towards the liquid level according to the preset speed, so that the piston cylinder generates air flow which is continuously blown outwards.

In order to form stable outward-blown air flow, the accuracy and stability of liquid level detection are improved. In this embodiment, the piston in the liquid transfer pump is controlled to move upward by a certain distance (for example, 30 mm), and then moves in the direction of the liquid surface at a predetermined speed.

It will be appreciated that the stroke may be defined according to the time requirement of detection, if the function of detecting the liquid level is required to be completed within 3 seconds, the movement time of the piston should be longer than 3 seconds, for example, the movement speed is 2mm/s, and the distance of upward movement is longer than 6mm, because the speed of movement of the stroke may be faster, and in this embodiment, the piston may be directly moved by 30mm.

The operation controls the liquid transferring pump to move towards the liquid level, and simultaneously controls the piston in the liquid transferring pump to move towards the liquid level according to the preset speed, so that the piston cylinder generates air flow which is continuously blown outwards, therefore, when the gun head of the liquid transferring pump is far away from the liquid level, the air pressure in the cavity of the piston cylinder is almost unchanged, when the tip of the gun head of the liquid transferring pump contacts the liquid level, the downward air flow is blocked instantaneously, a reverse air pressure is formed, and the air pressure sensor monitors that the original air pressure environment is changed, and instantly judges that the liquid level is detected.

In this embodiment, in order to avoid the problem that empty detection or empty suction is easy to occur when only a small amount of samples are available, the starting position of the liquid transfer pump can be recorded and positioned by using the position sensing device such as the photoelectric switch, the starting position of the liquid transfer pump is taken as the origin, the distance between the contact position of the liquid level detected by the liquid transfer pump and the origin is taken as the descending height, the depth of the liquid to be transferred is calculated by the distance between the bottom of the container for containing the liquid to be transferred and the origin, and the liquid volume to be transferred is calculated by combining the shape of the container.

For example, when the device is started and the pipetting process is performed, the pipetting pump is controlled to return to the initial position, and a photoelectric switch is arranged at the initial position to detect and determine the initial position of the pipetting pump, and the initial position is defined as the origin position. It can be understood that the operation of restoring the initial position can be confirmed by combining a plurality of pipetting pump assembly modules, single pipetting pump control and the like, and corresponding photoelectric switches and other elements can be arranged according to the requirement.

By using the method, whether the residual capacity of the container meets the target transfer requirement can be identified, the residual volume is calculated by combining the container shape through comparing the acquired descending height with the distance between the bottom of the container and the origin point acquired in advance, and the result that the liquid amount is sufficient or insufficient is identified. For example: using a cylindrical vessel with radius r, the remaining liquid volume v=pi r2x, x=the distance between the bottom of the vessel and the origin-the drop height.

S3: when the air pressure sensor in the liquid transfer pump collects that the variation difference value of the amplitude variation of the air pressure waveform is larger than the preset liquid level triggering threshold value, the liquid level is judged to be contacted and detected, and the liquid transfer pump piston is controlled to reset (namely, the piston returns to the initial position, and the liquid transfer operation is ready to be started according to the preset liquid transfer amount).

The liquid level triggering threshold is set according to the percentage of the change rate of the air pressure waveform amplitude acquired by the air pressure sensor on the reference amplitude, and when the percentage change difference is larger than the preset liquid level triggering threshold, the contact with the liquid level is judged.

In this embodiment, the air pressure waveform amplitude is subjected to the following filtering process: and acquiring air pressure values at time points with an interval of 100 mu s, sorting the air pressure values according to the air pressure values after acquiring the air pressure values at 30 time points, removing the air pressure values which are 5 before and 5 after sorting, and carrying out average value processing on the rest air pressure values to be used as a change difference value for judging the change of the amplitude of the air pressure waveform. In the filtering treatment, the head and tail maximum values are removed after sequencing, so that the defect of random interference in an arithmetic average filtering method is overcome, the filtering method is simple and high in efficiency, the judgment value is more reliable and stable by the filtering treatment mode, and the risk of misjudgment is avoided.

According to the pneumatic liquid level detection mode, whether the liquid level is contacted is judged according to the percentage of the change rate of the air pressure on the reference, and the judgment is not carried out according to the fixed air pressure change value, so that the problem of misjudgment caused by inapplicability of the air pressure value due to external factors such as the atmospheric pressure environment, the temperature environment and the like is solved, and the stability of air pressure detection is greatly enhanced.

S4: and controlling a piston in the liquid transfer pump to carry out liquid suction, and simultaneously controlling the liquid transfer pump to move downwards along with the descending of the liquid level, so that the depth of the gun head immersed in the liquid level is kept within a preset range.

Through the mode of the liquid level following, the liquid gun head is moved in the liquid suction process to always keep a certain immersed liquid level to follow the liquid level to descend, and the liquid level following function solves the problem caused by the fact that the liquid suction is empty or the gun head stretches into the liquid level too much under the condition of fixing the liquid level liquid suction height.

S4': and carrying out a pipetting quality monitoring step along with the pipetting step, wherein the pipetting quality monitoring step comprises the following steps: suction monitoring, bubble monitoring and blockage monitoring to realize the purpose of automatically distinguishing and monitoring the quality of the pipetting process by an unattended procedure.

The pipetting quality monitoring workflow is shown in fig. 4.

1) Suction monitoring: and comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging as suction when the variation difference of the amplitude variation of the air pressure waveform is smaller than the variation difference of the amplitude variation of the preset suction waveform in the pipetting process.

2) Blocking monitoring: comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging that the air pressure value waveform is blocked when the air pressure value waveform variation amplitude is larger than the preset normal waveform variation amplitude difference value and the air pressure value waveform is in a low-pressure state continuously in the pipetting process.

3) Bubble monitoring: comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging as a suction bubble when the air pressure value waveform variation amplitude is between a preset normal waveform variation amplitude difference value and a preset suction air waveform variation amplitude difference value in the pipetting process.

The normal waveform variation amplitude difference is larger than the suction waveform variation amplitude difference.

The principle of the monitoring is that when the liquid transferring pump sucks liquid, the pipeline is communicated with the atmosphere, the air pressure is sealed, the specific normal pressure value is maintained in the pipeline, if the liquid transferring pump sucks air, the original air pressure only slightly changes and basically keeps unchanged, and the change difference value of the amplitude change of the air pressure waveform is approximately zero; if the air bubble is sucked, the variation difference value of the amplitude variation of the air pressure waveform is smaller, namely the variation amplitude is between the preset normal waveform variation amplitude difference value and the preset suction waveform variation amplitude difference value; if a clot were to clog the gun head, the pressure would drop sharply and the sensor would be able to detect this anomaly.

It will be appreciated that when the transfer pump is performing a dispensing operation, a specific positive pressure is maintained in the pneumatic closed circuit and if a clot becomes clogged with the tip, the pressure will rise sharply and such abnormal changes will be detected by the module as well.

In this embodiment, the normal pipetting waveform and the suction waveform are determined by performing debugging through a preliminary experiment. Through the variation of the air pressure, whether the suction, the air bubble and the blockage accidents occur in the pipetting process can be detected in real time.

Fig. 5 shows waveforms of air pressure values acquired under different conditions, wherein each waveform is a suction air waveform curve, a suction air bubble waveform curve, a blockage occurrence waveform curve and a normal pipetting waveform curve. As can be seen from the figure, after the bubbles are sucked, the waveform amplitude of the air pressure value in the imbibition process is smaller due to the small amount of gas sucked; when the air is sucked, the waveform amplitude of the air pressure value only slightly changes, and the air pressure value is slightly changed after the air bubble is sucked, different from the air bubble is sucked; when the device is blocked, the negative pressure formed by suction cannot be timely supplemented with liquid, the amplitude of the waveform change of the air pressure value is larger in amplitude, and the low pressure state can be maintained for a longer time. The method can detect whether the accidents such as suction, air bubbles, blockage and the like occur in the pipetting process in real time through different changes of air pressure.

S5: and monitoring the collected air pressure value in real time to obtain an air pressure value which is an anti-falling initial value when the liquid suction is finished, and controlling the piston to move upwards to return to the liquid suction body when the waveform amplitude of the air pressure value changes beyond a threshold value, so that the air pressure value returns to the initial value range. The workflow of this drop prevention step is shown in fig. 6.

In the conventional technology, after pipetting is completed, liquid is usually directly sucked up for a trace stroke, that is, a part of air is sucked up and is remained at the tip of the gun head, so that the liquid drops are prevented from dripping again according to the difference of application scenes and the difference of air tightness, for example, the time of standing in a space after the liquid is sucked up by a pump is long, or the liquid drops are prevented from dripping again when the air tightness is poor. The problem that the air tightness is poor is generally solved by the conventional pipetting device, the situation that the air tightness is inconsistent is also solved by using the pipetting device with the same pipetting gun head, and the anti-dripping method utilizes the characteristic that the air tightness of the pipetting device is reflected in a positive correlation by the change of air pressure, and the purpose of circularly compensating and finally keeping no dripping is achieved by adopting the cyclic detection, so that the cross contamination problem of laboratories such as biology, chemistry, environment, medicine research and development, food and the like and units such as hospitals, disease control and blood stations and the like caused by the liquid transferring process is effectively solved.

In consideration of the fields of biology, medicine and the like, which require higher control precision of liquid drops, the liquid-transferring control quantity of the level of 1 mu l can be achieved when liquid is separated after liquid is absorbed, so that according to practical application scenes, such as 1000 mu l, 200 mu l and 10 mu l of liquid-transferring gun heads with larger differences and different specifications, the volumes and the weights of the formed liquid drops are also larger, and the liquid-transferring gun heads are not suitable for fixed stroke compensation.

In this embodiment, after the liquid is obtained and sucked into the gun head under the action of the piston pump, the air pressure collecting sensor monitors the amplitude change percentage of the air pressure waveform in the piston cylinder, when the air pressure waveform changes, the program self-adaptive algorithm controls the pump motor to drive the piston to vertically move upwards for a certain distance to drive the liquid to suck back for a certain capacity, so that the liquid in the gun head is maintained at the original position, the drop dropping is prevented, the problems of drop dropping precision deviation and drop dropping cross pollution caused by drop dropping in the standing or moving process in the liquid dropping process are solved, the air pressure waveform diagram is shown in fig. 7, wherein the 1, 3 and 5 points are the detected air pressure changes, and the 2, 4 and 6 points are subjected to drop compensation operation.

According to the method, different variable quantity thresholds are flexibly preset according to actual application scenes, and the variable quantity thresholds are set according to the relative proportion of initial values, so that the purposes of preventing liquid drops from dripping and accurately controlling liquid transfer are achieved.

Meanwhile, the embodiment sets a basic threshold value to enable the basic threshold value to exceed a preset threshold value for compensation, so that the pump is prevented from frequently compensating, and the service life of equipment is prolonged.

S6: and controlling a piston in the liquid transferring pump to separate liquid, and simultaneously controlling the liquid transferring pump to move upwards along with the rising of the liquid level, so that the distance between the gun head and the liquid level is kept within a preset range.

Through the mode that above-mentioned liquid level follows, move liquid rifle head in the imbibition in-process and follow the liquid level with keeping having certain height all the time and rise along the liquid level, solved in the liquid in-process liquid and be stained with the problem that the rifle head outer wall leads to the result inaccurate easily.

S7: the liquid was emptied.

The emptying function is to completely discharge the liquid in the gun head, and mainly solves the problems of uncleanness in liquid separation and blockage. According to the design method, after the liquid is sucked, when a emptying function is started, the stroke of the liquid transferring pump is the stroke reserved for the amount of the sucked liquid, so that the liquid is completely discharged, the liquid transferring pump is automatically reset to reserve a stroke capable of exhausting air again after the liquid is emptied, and the emptying function can be recycled in the liquid transferring process.

The pipetting control method of the pneumatic pipetting pump improves sensitivity and stability in the liquid level detection process, does not need high-cost special consumables such as electric conduction and the like, has no problem of exceeding standard of radiation emission, and efficiently executes various operations such as serum separation, bacterial liquid transfer, nucleic acid transfer and the like transferred from a tube to a plate.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. A pipetting control method of a pneumatic pipetting pump, comprising a liquid level detection step comprising:

s1: starting an air pressure real-time acquisition system to acquire an air pressure value in a piston cylinder of the liquid transfer pump;

s2: controlling the liquid transfer pump to move towards the liquid level, and simultaneously controlling the piston in the liquid transfer pump to move towards the liquid level according to a preset speed, so that the piston cylinder generates air flow which is continuously blown outwards;

s3: when the air pressure sensor in the liquid transfer pump collects that the variation difference value of the amplitude variation of the air pressure waveform is larger than the preset liquid level triggering threshold value, the liquid level is judged to be contacted and detected.

2. The method according to claim 1, wherein in step S2, the piston in the liquid transfer pump is controlled to move upward by a predetermined distance and then to move in the direction of the liquid surface at a predetermined speed.

3. The method according to claim 1, wherein in the step S2, the distance between the origin and the contact position of the liquid surface detected by the liquid transfer pump is the descending height, the depth of the liquid to be transferred is calculated by the distance between the bottom of the container containing the liquid to be transferred and the origin, and the volume of the liquid to be transferred is calculated by combining the shape of the container.

4. The method according to claim 1, wherein in step S3, the amplitude of the pneumatic waveform is subjected to the following filtering process: and acquiring air pressure values at preset time points, sorting the air pressure values according to the air pressure values after acquiring the air pressure values at a plurality of time points, removing a plurality of air pressure values before and after sorting, and carrying out average value processing on the rest air pressure values to be used as a change difference value for judging the change of the amplitude of the air pressure waveform.

5. The method according to claim 4, wherein in step S3, the amplitude of the pneumatic waveform is subjected to the following filtering process: and acquiring air pressure values at time points with an interval of 100+/-20 mu s, sorting the air pressure values according to the air pressure values after acquiring the air pressure values at 30+/-10 time points, removing the air pressure values which are 5+/-3 before and 5+/-3 after sorting, and carrying out average value processing on the rest air pressure values to be used as a change difference value for judging the change of the amplitude of the air pressure waveform.

6. The pipetting control method of a pneumatic pipetting pump according to claim 1, further comprising a pipetting step of:

s4: and controlling a piston in the liquid transfer pump to carry out liquid suction, and simultaneously controlling the liquid transfer pump to move downwards along with the descending of the liquid level, so that the depth of the gun head immersed in the liquid level is kept within a preset range.

7. The pipetting control method of a pneumatic pipetting pump according to claim 1, further comprising a pipetting quality monitoring step performed with the pipetting step, the pipetting quality monitoring step comprising: suction monitoring, bubble monitoring and blockage monitoring;

the suction monitoring comprises the following steps: comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging as suction when the variation difference of the amplitude variation of the air pressure waveform is smaller than the variation difference of the amplitude variation of a preset suction waveform in the pipetting process;

the occlusion monitoring comprises the steps of: comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging that the air pressure value waveform is blocked when the air pressure value waveform variation amplitude is larger than the preset normal waveform variation amplitude difference value and the air pressure value waveform is in a low-pressure state continuously in the pipetting process;

the bubble monitoring comprises the following steps: comparing the air pressure value waveform acquired in real time with a preset normal pipetting waveform, and judging as a suction bubble when the air pressure value waveform variation amplitude is between a preset normal waveform variation amplitude difference value and a preset suction air waveform variation amplitude difference value in the pipetting process;

the normal waveform variation amplitude difference is larger than the suction waveform variation amplitude difference.

8. The method according to any one of claims 1 to 7, characterized by further comprising a drop prevention step after completion of the pipetting step, the drop prevention step comprising:

s5: and monitoring the collected air pressure value in real time to obtain an air pressure value which is an anti-falling initial value when the liquid suction is finished, and controlling the piston to move upwards to return to the liquid suction body when the waveform amplitude of the air pressure value changes beyond a threshold value, so that the air pressure value returns to the initial value range.

9. The pipetting control method of a pneumatic pipetting pump of claim 8, further comprising a pipetting step comprising:

s6: and controlling a piston in the liquid transferring pump to separate liquid, and simultaneously controlling the liquid transferring pump to move upwards along with the rising of the liquid level, so that the distance between the gun head and the liquid level is kept within a preset range.

10. A pneumatic transfer pump, comprising: a pipetting assembly and a pipetting control system for performing pipetting using the control method of any one of claims 1-9.