A liquid absorption method based on liquid surface tension for preventing liquid hanging and a pneumatic pipette

Abstract

The present invention provides a liquid absorption method and a pneumatic pipette for preventing liquid hanging based on the surface tension of a liquid, which relates to the technical field of pipettes. The method includes using a pressure detection device to record the pressure state Q0 of the pneumatic pipette in the initialization mode; performing a liquid level detection operation and recording the current reagent height H0; controlling the pneumatic pipette to perform a blowing operation, detecting the change of the pressure in real time during the blowing operation, and recording the output signal at the time point of steep drop during the change process and the height value of the real-time z-axis corresponding to the time point, confirming whether the reagent height H0 is correct, and recording the confirmed height as the reference height H1; controlling the pneumatic pipette to descend to the reference height H1 and sucking a preset liquid absorption volume V n and then stopping; calculating according to the reference height H1 and the preset liquid absorption volume V n to obtain the liquid absorption position H for each time n . The beneficial effect of the present invention is to prevent liquid from hanging on the inner and outer walls of the TIP tip by using the surface tension of the reagent on the liquid surface, and the improvement effect is obvious, and there is no obvious reagent on the TIP tip.

Description

Technical Field

[0001] The present invention relates to the technical field of pipettes, and in particular, to a liquid suction method based on liquid surface tension for preventing liquid hanging and a pneumatic pipette. Background Art

[0002] Whether it is capacitance or air pressure for detecting the liquid level, during this process, the device controls the pipette not to descend further. The control mechanism can control the tip of the TIP to be immersed in the reagent by 1 - 3 mm at this time. At this time, the tip of the TIP is immersed in the reagent, which destroys the liquid surface tension and causes a small amount of reagent to enter the TIP, affecting the accuracy and CV of the micro - liquid transfer of the pipette. And when further performing liquid transfer operations with reagents of different viscosities from 1 - 200 cP, the phenomenon that the destruction of the liquid surface tension causes a small amount of reagent to enter the TIP becomes more obvious as the viscosity decreases, and the resulting impact on accuracy is also more serious.

[0003] During the experiment, when directly leaving the liquid surface without a blowing action, there will be a phenomenon that the destruction of the liquid surface tension causes a small amount of reagent to enter the TIP at the front end of the TIP. Due to the surface adhesion force formed by the liquid inside the TIP, this part of the reagent will not fall off automatically when the TIP is taken out of the reagent. After leaving the liquid surface, an attempt is made to introduce blowing to remove this part of the reagent. However, removing the reagent at the front end of the TIP is likely to cause the reagent to be blown onto the outer wall of the TIP tip by the air pressure eddy current, and this part of the reagent will also affect the subsequent micro - liquid discharge accuracy. Summary of the Invention

[0004] The purpose of the present invention is to provide a liquid suction method based on liquid surface tension for preventing liquid hanging and a pneumatic pipette to improve the above - mentioned problems. To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0005] In a first aspect, the present application provides a pneumatic pipette, including a pipette body, and the pipette body includes:

[0006] A tip, having an inner cavity; a TIP head, disposed at the lower end of the tip;

[0007] An air pressure detection module, including at least a first detection port and a second detection port; the first detection port is communicated with the inner cavity of the tip, the second detection port is communicated with the external environment, and a sensor is disposed at the first detection port;

[0008] Wherein, when the whole pneumatic pipette descends, the inner cavity is communicated with the sensor. When the TIP head descends to contact the reagent, the reagent enters the TIP interior, and when the pneumatic pipette detects an increase in air pressure, it will send out a signal, thereby driving the mechanism to control the pneumatic pipette to stop descending. The driving mechanism is used to control the movement of the pneumatic pipette.

[0009] Preferably, an alarm mechanism is further included in the pipette body, and the alarm mechanism is used to give an alarm prompt for the failure of the liquid level detection of the pneumatic pipette, the failure of the pneumatic pipette, and the overlimit of the driving mechanism.

[0010] In a second aspect, the present application also provides a liquid suction method for preventing liquid hanging based on the surface tension of the liquid, including:

[0011] Set the pneumatic pipette to the initialization mode, and use the air pressure detection device to record the air pressure state Q of the pneumatic pipette in the initialization mode 0 ;

[0012] Perform a liquid level detection action by using the capacitance method or the air pressure method, stop the detection after detecting the reagent liquid level signal, and record the current reagent height H 0 ;

[0013] Control the pneumatic pipette to perform a blowing operation, detect the change of the air pressure during the blowing operation in real time, and record the output signal at the time point of the steep drop during the change and the height value of the real-time Z-axis corresponding to the time point, and confirm the reagent height H 0 Whether it is correct, and record the confirmed height as the reference height H 1 ;

[0014] Control the pneumatic pipette to descend to the reference height H 1 and perform a liquid suction action to suck a preset liquid suction volume V n and then stop;

[0015] According to the reference height H 1 and the preset liquid suction volume V n calculate to obtain the liquid suction position H for each time n , repeat the above steps to record the height H confirmed when leaving the liquid surface after each liquid level detection 2n , and compare H 2n with the calculation result H n for verification to obtain a verification result.

[0016] Preferably, when performing the liquid level detection action and stopping the detection after detecting the reagent liquid level signal, it includes:

[0017] Send a first control command, and the first control command is to control the pneumatic pipette to move downward to detect the reagent liquid level;

[0018] Receive a first signal, and the first signal is a feedback detection success signal sent when the pneumatic pipette detects the reagent liquid level, and the detection of the reagent liquid level means that the front end of the TIP head of the pneumatic pipette touches the reagent liquid level;

[0019] Compare the first signal with a preset signal to determine whether it is a signal indicating contact with the reagent liquid level; if so, drive the pneumatic pipette to stop moving towards the reagent liquid level, and if not, give an alarm.

[0020] Preferably, the real-time detection of the change in air pressure during the blowing operation includes:

[0021] Judge whether the air pressure value when the pneumatic pipette is not in contact with the reagent liquid level has returned to the air pressure state Q 0 , if it has returned to the air pressure state Q 0 , then the pneumatic pipette enters the state where it can aspirate the reagent; if it has not returned to the air pressure state Q 0 , then give an alarm.

[0022] Preferably, record the output signal at the time point of the steep drop during the change process and the height value of the real-time Z-axis corresponding to the time point to confirm the reagent height H 0 Whether it is correct, and record the confirmed height as the reference height H 1 , which includes:

[0023] Obtain the change in air pressure of the pneumatic pipette during the process of leaving the reagent liquid level;

[0024] Record the output signal at the time point of the steep drop during the air pressure change process and the height value of the Z-axis at this time corresponding to the recorded time point of the steep drop;

[0025] Compare the obtained height value of the Z-axis with the reagent height H 0 Judge whether the height value is close to the reagent height H 0 If they are close, it is confirmed successfully, and the confirmed height is recorded as the reference height H 1 ; if they are not close, it is confirmed as failed and an alarm is given.

[0026] Preferably, calculate based on the reference height H 1 and the preset liquid aspiration volume V n to obtain the liquid aspiration position H each time n , which includes that if the preset liquid aspiration volume V n drops by H (Vn) in the reagent container, then the liquid aspiration position is H n =H 1 -H (Vn) .

[0027] Preferably, set a rated liquid aspiration range, judge whether the liquid aspiration position H n exceeds the rated range, and if it exceeds the rated range, give an alarm.

[0028] Preferably, the preset liquid aspiration volume V n is 9.5 - 10.5 ul.

[0029] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0030] After the pipette of the present invention is installed with a TIP, due to the airtightness, a small amount of reagent will enter as the depth of insertion into the liquid increases. However, the reagent entering the TIP will not continuously increase with the increase of the depth of insertion into the liquid surface. As it slowly leaves the liquid surface, the pressure P = ρgh at the front end of the TIP will gradually decrease. Along with the driving motor blowing air to make the TIP leave the liquid surface, the reagent entering the front end of the TIP can be effectively discharged from the TIP. In this process, the blowing action is relatively slow and will not cause the reagent to splash. When leaving the liquid surface, by using the surface tension of the original reagent liquid and the introduced blowing process, the reagent at the front end and outer wall of the TIP can be retained in the original reagent. Using the method of the present invention to blow out the reagent in the TIP, and at the same time using the surface tension of the reagent on the liquid surface to prevent liquid from hanging on the inner and outer walls of the TIP tip, while ensuring the effect of the liquid surface detection function, it reduces the impact of the entry of trace reagents into the TIP on the pipetting accuracy, and the improvement effect is obvious.

[0031] Other features and advantages of the present invention will be described in the subsequent specification, and part of them will become obvious from the specification, or can be understood by implementing the embodiments of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the structures specifically pointed out in the written specification, claims, and drawings. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0033] Figure 1 The front view of the drive structure and pneumatic pipette provided by the embodiment of the present invention;

[0034] Figure 2 The structural schematic diagram of the pneumatic pipette provided by the embodiment of the present invention;

[0035] Figure 3 The partial cross-sectional view at the tip of the pipette provided by the embodiment of the present invention;

[0036] Figure 4 The schematic flow chart of the liquid absorption method for preventing liquid from hanging based on the surface tension of the liquid provided by the embodiment of the present invention;

[0037] In the figure: 1 - pipette body, 11 - tip, 11a - inner cavity, 12a - sensor, 2 - TIP head, 3 - driving member. Detailed implementation mode

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0040] Embodiment:

[0041] In the prior art, whether it is capacitance or air pressure used to detect the liquid level, during this process, the device controls the pipette to stop descending further, and the control mechanism can control the tip of the TIP to be immersed in the reagent by 1-3 mm at this time. At this time, the tip of the TIP is immersed in the liquid surface of the reagent, breaking the liquid surface tension and causing a small amount of reagent to enter the TIP, affecting the accuracy and CV of the micro-pipetting of the pipette. When further performing pipetting operations with reagents having different viscosities of 1-200 cP, the phenomenon of a small amount of reagent entering the TIP due to the breakage of the liquid surface tension becomes more obvious as the viscosity decreases, and the resulting impact on accuracy is also more serious.

[0042] Therefore, referring to Figures 1-3 , this embodiment provides a pneumatic pipette, including a pipette body 1, and the pipette body 1 includes:

[0043] A tip 11 having an inner cavity 11a; a TIP head 2 provided at the lower end of the tip 11;

[0044] An air pressure detection module, at least including a first detection port and a second detection port; the first detection port is communicated with the inner cavity 11a of the tip 11, the second detection port is communicated with the external environment, and a sensor 12a is provided at the first detection port;

[0045] It should be noted that the pressure detection module has at least a first detection port and a second detection port. Among them, the first detection port is communicated with the inner cavity 11a of the gun head 11 to detect the air pressure in the inner cavity 11a of the gun head 11, and the second detection port is communicated with the external environment to detect the air pressure in the external environment. It can be understood that the pressure detection module in this embodiment can be a differential pressure sensor with two detection probes. At this time, one of the detection probes of the differential pressure sensor is communicated with the first detection port, and the other detection probe of the differential pressure sensor is communicated with the second detection port to detect the air pressure in the inner cavity 11a of the gun head 11 and the external environment respectively; of course, the pressure detection module can also be two independent pressure sensors. At this time, the detection probe of one pressure sensor is communicated with the first detection port, and the detection probe of the other pressure sensor is communicated with the second detection port. The air pressure in the inner cavity 11a of the gun head 11 and the external environment can also be detected respectively through the two pressure sensors. The specific setting method of the pressure detection module is not specially limited here. In this embodiment, a sensor 12a is provided at the first detection port.

[0046] The pressure detection module of this embodiment is arranged inside the pipette body 1. At this time, continue to refer to Figure 2 , a sensor 12a communicated with the inner cavity 11a of the gun head 11 is arranged on the pipette body 1. The first detection port of the pressure detection module is connected to the inner cavity 11a of the gun head 11 through the sensor 12a to detect the pressure in the inner cavity 11a of the gun head 11 by using the pressure detection module.

[0047] Among them, when the pneumatic pipette as a whole descends, the inner cavity 11a is communicated with the sensor 12a. When the TIP head 2 descends to contact the reagent, since the reagent enters the TIP, the pneumatic pipette detects an increase in air pressure and will send out a signal of "liquid level detected", thereby driving the mechanism to control the pneumatic pipette to stop descending. The driving mechanism is used to control the movement of the pneumatic pipette.

[0048] It should be noted that the driving mechanism includes a driving member 3. The driving member 3 is movably connected to the pipette body 1, and the driving member 3 is used to control the movement of the pneumatic pipette.

[0049] An alarm mechanism is further included in the pipette body 1. The alarm mechanism is used to give an alarm prompt for the failure of the liquid level detection of the pneumatic pipette, the failure of the pneumatic pipette, and the overlimit of the driving mechanism.

[0050] Next, the specific liquid suction method based on liquid surface tension to prevent liquid hanging will be elaborated in detail. Combining Figure 4 with the schematic flow chart of the liquid suction method based on liquid surface tension to prevent liquid hanging shown, this liquid suction method includes the following steps:

[0051] This embodiment provides a liquid absorption method for preventing liquid hanging based on the surface tension of a liquid, including step S100, step S200, step S300, step S400, and step S500.

[0052] S100. Set the pneumatic pipette to the initialization mode, and use a pressure detection device to record the air pressure state Q of the pneumatic pipette in the initialization mode. 0 .

[0053] S200. Use the capacitance method or the air pressure method to perform a liquid level detection operation. After detecting the reagent liquid level signal, stop the detection, and record the current reagent height H. 0 .

[0054] It can be understood that in this step S200, it includes S201, S202, and S203, where:

[0055] S201. Send a first control command, and the first control command is to control the pneumatic pipette to move downward to detect the reagent liquid level.

[0056] It should be noted that the Z-axis drive controls the pipette to move downward, and at the same time, the pipette performs a liquid level detection operation.

[0057] S202. Receive a first signal, and the first signal is a feedback signal indicating successful detection when the pneumatic pipette detects the reagent liquid level. The detection of the reagent liquid level means that the front end of the TIP head 2 of the pneumatic pipette touches the reagent liquid level.

[0058] It should be noted that when the liquid level is detected, a feedback signal indicating successful detection is sent, and the successful signal is the signal sent when the reagent liquid level is detected, and this signal is received.

[0059] S203. Compare the first signal with a preset signal to determine whether it is a signal indicating contact with the reagent liquid level; if so, drive the pneumatic pipette to stop moving towards the reagent liquid level, and if not, give an alarm.

[0060] It should be noted that drive the device to stop the pipette from moving towards the reagent, record the current reagent height H. 0 , if the liquid level is not detected within the specified range during the movement, an alarm is given. After detecting the reagent, the Z-axis drive controls the pipette to stop. During the detection process, all devices will submerge below the liquid level after detecting the reagent liquid level, so the front end of the TIP, that is, the front end of the TIP head 2, is below the reagent surface.

[0061] S300. Control the pneumatic pipette to perform a blowing operation, and continuously detect the change of air pressure during the blowing operation, and record the output signal at the time point of steep drop during the change process and the corresponding real-time Z-axis height value at the time point to confirm the reagent height H. 0Whether it is correct, and record the confirmed height as the reference height H 1 。

[0062] It can be understood that in this step S300, S301, S302, S303, and S304 are included, where:

[0063] S301. Determine whether the air pressure value when the pneumatic pipette does not contact the reagent liquid level returns to the air pressure state Q 0 ;

[0064] If it has returned to the air pressure state Q 0 at this time, the pneumatic pipette enters the state where it can aspirate the reagent; if it has not returned to the air pressure state Q 0 , an alarm is given.

[0065] S302. Obtain the air pressure change situation of the pneumatic pipette during the process of leaving the reagent liquid level;

[0066] S303. Record the output signal at the time point of the steep drop during the air pressure change process and record the height value of the Z-axis at this time corresponding to the time point of the steep drop;

[0067] S304. Compare the obtained height value of the Z-axis with the reagent height H 0 and determine whether the height value is close to the reagent height H 0 If they are close, it is confirmed as successful, and the confirmed height is recorded as the reference height H 1 ; if they are not close, it is confirmed as failed and an alarm is given.

[0068] It should be noted that after successfully detecting the liquid level, the Z-axis drives to control the pipette to leave the liquid level, and at the same time the pipette performs a blowing operation. When it is detected that the air pressure (the air pressure when not in contact with the liquid level) returns to the state Q recorded in step S100 0 at this time, the pipette state quickly becomes ready and enters the state where it can aspirate the reagent (if the air pressure cannot return to the Q 0 state, an alarm is given).

[0069] When driving the motor to blow air and leaving the liquid level, the air pressure change is detected in real time. When leaving the liquid level, the air pressure rises slowly and then drops steeply. At the same time, the output signal at the time point of this steep drop should be recorded, and the height of the Z-axis at this time corresponding to the time point is recorded, so as to further confirm whether the reagent height H 0 detected by the liquid level detection in step S200 is correct, and the confirmed height is used as the reference H1. It should be added that if the two values are close, it means success and confirmation is performed, otherwise it is failure and an alarm is given.

[0070] S400. Control the pneumatic pipette to descend to the reference height H 1 and perform a liquid aspiration action to aspirate the preset liquid aspiration volume V nStop afterwards.

[0071] It can be understood that in this step, according to the reference height H 1 and the preset liquid suction volume V n calculations are performed to obtain the liquid suction position H each time n , including if the preset liquid suction volume V n descends by H in the reagent container (Vn) , then the liquid suction position is H n = H 1 - H (Vn) .

[0072] It should be noted that the preset liquid suction volume V n is set by the user independently. After using the method of the present invention (the method of blowing air away from the liquid surface), it avoids the communication delay from the detection success signal to the stop of the Z-axis drive, and the influence on accuracy caused by different Z-axis drive speeds resulting in different immersion depths of the TIP tip after the liquid surface is detected and different reagent volumes for this part.

[0073] S500. According to the reference height H 1 and the preset liquid suction volume V n calculations are performed to obtain the liquid suction position H each time n , repeat the above steps to record the height H confirmed when leaving the liquid surface after each liquid surface detection 2n , and compare H 2n with the calculation result H n to obtain the verification result.

[0074] It can be understood that in this step, a rated liquid suction range is set, and it is judged whether the liquid suction position H n exceeds the rated range. If it exceeds the rated range, an alarm is given.

[0075] It should be noted that the liquid surface detection of steps S200 - S400 is repeated, and the height H confirmed when leaving the liquid surface after the nth liquid surface detection is recorded 2n . According to the reference height H recorded in step S300 1 and the liquid suction volume V n calculations are performed; assuming that V n the reagent descends by H in the reagent container (Vn) , then the liquid suction position H each time n = H 1 - H (Vn) , if the Z-axis drive position H n exceeds the rated range, an alarm is given.

[0076] In summary, when the liquid surface detection is repeated, H 2n can be compared with the calculation result H nPerform verification to further confirm that the liquid is aspirated at a fixed position below the liquid level each time, and there will be no precision error caused by factors such as communication and Z-axis speed.

[0077] Further, the preset liquid aspiration volume V n is 9.5 - 10.5 ul. In this embodiment, when measuring micro liquid discharge, the theoretical liquid aspiration is 10 ul, and the theoretical weight should be 9.997 mg. Affected by atmospheric pressure, temperature, humidity, evaporation, etc., the measured weight of the reagent should be less than this theoretical value. Through the method of the present invention, the influence of the reagent attached to the front end of the TIP on the precision instability can be reduced, and at the same time, the overall CV also shows a downward trend. This method can obtain more stable data, more truly reflect the performance of the pipette, and is more referenceable.

[0078] To sum up, after the pipette is installed with the TIP, due to the airtightness, a small amount of reagent will enter as the penetration depth into the liquid increases. However, the reagent entering the TIP does not continuously increase with the penetration depth into the liquid surface. As it slowly leaves the liquid surface, the pressure P = ρgh at the front end of the TIP will gradually decrease. Along with the driving motor blowing air into the TIP to leave the liquid surface, the reagent entering the front end of the TIP can be effectively discharged from the TIP; during this process, the blowing action is relatively slow and will not cause the reagent to splash. When leaving the liquid surface, by using the surface tension of the original reagent liquid and the introduced blowing process, the reagent on the front end and outer wall of the TIP can be retained in the original reagent.

[0079] It should be further noted that during the process of blowing air after leaving the liquid surface, the sudden change in air flow forms a vortex on the outer wall of the tip. Due to the hydrophobicity of the TIP material, a liquid bead with an apparent contact angle α > 90° is formed, which affects the micro liquid discharge performance. It is concluded in the experiment that when directly leaving the liquid surface without a blowing action, there will be a phenomenon that the surface tension of the liquid is damaged at the front end of the TIP, resulting in a small amount of reagent entering the TIP; due to the surface adhesion force formed by the liquid inside the TIP, this part will not fall off by itself when the TIP is taken out of the reagent. After leaving the liquid surface, an attempt is made to introduce blowing to remove this part of the reagent. However, when removing the reagent at the front end of the TIP, it is very likely that the reagent will be blown onto the outer wall of the TIP tip by the air pressure vortex, and this part of the reagent will affect the subsequent micro liquid discharge precision. But when slowly blowing air when leaving the liquid surface, that is, using the method of the present invention, an attempt is made to blow out the reagent in the TIP, and at the same time, the surface tension of the reagent on the liquid surface is used to prevent the liquid from hanging on the inner and outer walls of the TIP tip; the improvement effect is obvious, and there is no obvious reagent at the TIP tip.

[0080] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A liquid absorption method for preventing liquid hanging based on liquid surface tension, which is realized by a pneumatic pipette. The pneumatic pipette includes a pipette body, and the pipette body includes a tip, a TIP head, a pressure detection module and an alarm mechanism. The TIP head is arranged at the lower end of the tip. The pressure detection module includes at least a first detection port and a second detection port. The first detection port is communicated with the inner cavity of the tip, and the second detection port is communicated with the external environment. A sensor is arranged at the first detection port. When the whole pneumatic pipette descends, the inner cavity is communicated with the sensor. When the TIP head descends to contact the reagent, the reagent enters the TIP head. When the pneumatic pipette detects an increase in pressure, it sends a signal to make the driving mechanism control the pneumatic pipette to stop descending. The alarm mechanism is used to give an alarm prompt for the failure of the liquid level detection of the pneumatic pipette, the failure of the pneumatic pipette and the overlimit of the driving mechanism. It is characterized in that The liquid absorption method for preventing liquid hanging based on liquid surface tension includes: Set the pneumatic pipette to the initialization mode, and use the air pressure detection module to record the air pressure state Q of the pneumatic pipette in the initialization mode 0 ; Perform the liquid level detection operation using the capacitance method or the air pressure method. Stop the detection after detecting the reagent liquid level signal and record the current reagent height H 0 ; Control the pneumatic pipette to perform a blowing operation, detect the change of air pressure in real time during the blowing operation, and record the output signal at the time point of sharp drop during the change process and the height value of the real-time Z-axis corresponding to the time point, and confirm the reagent height H 0 Whether it is correct, and record the confirmed height as the reference height H 1 ; Control the pneumatic pipette to descend to the reference height H 1 and perform a liquid aspiration operation to aspirate a preset liquid aspiration volume V n and then stop; According to the reference height H 1 and the preset liquid suction volume V n perform calculations to obtain the liquid suction position H each time n , including if the preset liquid suction volume V n descends by H (Vn) in the reagent container, then the liquid suction position is H n = H 1 - H (Vn) . Repeat the above steps to record the height H confirmed when leaving the liquid surface after each liquid level detection 2n , and compare H 2n with the calculation result H n for verification to obtain the verification result and confirm that liquid is suctioned at a fixed position below the liquid surface each time.

2. The liquid absorption method for preventing liquid hanging based on liquid surface tension according to claim 1, It is characterized in that Performing a liquid level detection action and stopping the detection after detecting a reagent liquid level signal, which includes: Sending a first control command, which is to control the pneumatic pipette to move downward to detect the reagent liquid level; Receiving a first signal, which is a signal fed back to indicate successful detection when the pneumatic pipette detects the reagent liquid level. Detecting the reagent liquid level means that the front end of the TIP head of the pneumatic pipette contacts the reagent liquid level; Comparing the first signal with a preset signal to judge whether it is a signal of contacting the reagent liquid level. If so, drive the pneumatic pipette to stop moving towards the reagent liquid level. If not, give an alarm.

3. The liquid absorption method for preventing liquid hanging based on liquid surface tension according to claim 1, It is characterized in that Real-time detecting the change of pressure during the blowing operation, which includes: Determine whether the air pressure value of the pneumatic pipette returns to the air pressure state Q when it does not touch the reagent liquid level 0 If it has returned to the air pressure state Q 0 then the pneumatic pipette enters the state where it can aspirate the reagent; if it has not returned to the air pressure state Q 0 then an alarm is given.

4. The liquid absorption method for preventing liquid hanging based on liquid surface tension according to claim 1, It is characterized in that The output signal at the time point when the record drops steeply during the change process and the height value of the real-time Z-axis corresponding to the time point are used to confirm the reagent height H 0 to check whether it is correct, and record the confirmed height as the reference height H 1 , including: Obtaining the change of pressure of the pneumatic pipette during the process of leaving the reagent liquid level; Recording the output signal at the time point of steep drop during the pressure change process and the height value of the Z-axis corresponding to the time point of steep drop at this time; Compare the obtained height value of the Z-axis with the reagent height H 0 to determine whether the height value is close to the reagent height H 0 If they are close, confirm success and record the confirmed height as the reference height H 1 ; if not, confirm failure and give an alarm.

5. The liquid absorption method for preventing liquid hanging based on liquid surface tension according to claim 4, It is characterized in that Set the rated liquid suction range and determine the liquid suction position H n Check if it exceeds the rated range. If it exceeds the rated range, an alarm will be triggered.

6. The liquid absorption method for preventing liquid hanging based on liquid surface tension according to claim 1, It is characterized in that The preset liquid absorption volume V n is 9.5 - 10.5 ul.

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