JP2015190946A - Liquid dispensing device and liquid dispensing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid dispensing device increased in dispensing accuracy using the device which suppresses reduction in sucking amount of a liquid which may be generated when sucking and discharging of the liquid is repeated using identical inlet and outlet nozzles.SOLUTION: A liquid dispensing device includes: liquid dispensing means for dispensing a constant amount of a liquid, which is provided with a nozzle, an air pipe communicating to the nozzle, and a pump for transmitting a sucking and discharging force to the nozzle via the air pipe; and drive means for driving the pump. The liquid dispensing device is further provided with a pressure open valve for the air pipe provided in the liquid dispensing means, and solves a problem by a liquid dispensing method that performs a pressure open operation by the pressure open valve before performing the next liquid dispensing operation after the liquid dispensing operation performed by the liquid dispensing means provided in the liquid dispensing device.

Description

  The present invention relates to a liquid dispensing apparatus for dispensing a liquid sample (specimen, reagent, washing liquid, etc.) and a liquid dispensing method using the liquid dispensing apparatus.

  2. Description of the Related Art An automatic dispensing device that dispenses and transfers a certain amount of liquid using a suction / discharge nozzle that discharges from the same end as a suction end is widely used in various industrial fields. In many of these automatic dispensing apparatuses, a syringe pump having a piston driving means with a fixed stroke is used as a metering pump for dispensing a fixed amount of liquid. The metering pump and the nozzle are connected by piping, and the gas (mostly air) in the piping is a pressure transmission medium.

  When liquid is sucked and discharged using the suction / discharge nozzle, there is a case where liquid remaining after discharge adheres to the tip of the nozzle and remains. Since the adhering and remaining liquid may block the tip of the nozzle in the form of a film or a droplet, it is preferable that all the liquid sucked into the nozzle is discharged. As a method of discharging all the liquid sucked into the nozzle, a method of sucking air before sucking the liquid and discharging the air after discharging the liquid is usually performed.

  As described above, as a method of discharging all the liquid sucked into the nozzle, a method of sucking air before sucking the liquid and discharging the air after discharging the liquid is performed. However, if the liquid to be sucked and discharged is a liquid that tends to clog the nozzle tip due to liquid droplets or a liquid film, the liquid adhering to the inner wall of the nozzle due to the air discharge gathers at the nozzle tip and closes the nozzle and discharges air There is a possibility that the pressure inside the pipe will be positively increased by that amount. In addition, there is a possibility that the heat generated from the inside of the automatic analyzer provided with the dispensing device warms the air inside the intake / exhaust nozzle and the piping, and the pressure inside the blocked intake / exhaust nozzle and the piping becomes positive. When the pressure inside the intake / exhaust nozzle or the pipe becomes positive, the pressure reduction operation of the metering pump is constant, so when sucking the liquid again, the degree of vacuum in the pipe and the nozzle is insufficient and the liquid suction amount decreases. Can happen.

  Therefore, the present invention uses a liquid dispensing apparatus that suppresses a decrease in the amount of liquid suction that can occur when liquid suction and discharge are repeated using the same suction / discharge nozzle, and improves the dispensing precision, and the liquid dispensing apparatus. An object of the present invention is to provide a liquid dispensing method.

  This invention made | formed in view of the said subject includes the following aspects.

That is, the first aspect of the present invention is:
A liquid dispensing means for dispensing a fixed amount of liquid, comprising a nozzle, an air pipe communicating with the nozzle, and a pump for transmitting suction and discharge force to the nozzle through the air pipe;
Drive means for driving the pump;
A liquid dispensing device comprising:
In the liquid dispensing apparatus, a pressure release valve is further provided in an air pipe provided in the liquid dispensing unit.

  A second aspect of the present invention is the liquid dispensing according to the first aspect, wherein after the liquid is dispensed by the liquid dispensing means, the pressure relief operation is performed by the pressure relief valve before the next liquid dispensing. This is a liquid dispensing method using a pouring device.

  In the present invention, the nozzle may be fixed or screwed to the distal end of the pipe, or may be in the form of a dispensing tip that can be attached to and detached from the distal end of the pipe.

  The present invention provides a liquid dispensing means for dispensing a predetermined amount of liquid, provided with a nozzle, an air pipe communicating with the nozzle, and a pump for transmitting suction and discharge force to the nozzle through the air pipe, and driving the pump In the liquid dispensing apparatus provided with the driving means to be operated, a pressure release valve is further provided in the air pipe.

  In the present invention, the nozzle tip is closed in the form of a film or a droplet by the liquid remaining from the discharge, so that the positive pressure inside the pipe can be easily eliminated even when the pressure inside the pipe becomes positive. it can. Therefore, it is possible to suppress the sporadic decrease in the amount of suction that can occur when the liquid is repeatedly sucked and discharged using the same dispensing nozzle, and the effect of increasing the dispensing accuracy can be obtained.

It is a figure which shows the one aspect | mode of the liquid dispensing apparatus which concerns on this invention. FIG. 6 is a diagram showing actual measurement values of suction amount / discharge amount in Comparative Example 1; It is a figure which shows the pressure change inside the piping in the comparative example 1. FIG. It is a figure which shows the actual value of the suction amount / discharge amount in Example 1. FIG. It is a figure which shows the pressure change inside the piping in Example 1. FIG.

  As one mode for carrying out the present invention, FIG. 1 shows a liquid dispensing apparatus 100 provided with eight nozzles. The liquid dispensing apparatus shown in FIG. 1 is suitably used for a nucleic acid analyzer that processes a large number of specimens at high speed.

  In FIG. 1, the syringe pump 12 communicates with an air pipe 13 in a form corresponding to each nozzle 11. The eight syringe pumps 12 are driven by driving means 20 (for example, means based on a stepping motor). A container 30 containing a sample (specimen, reagent, cleaning liquid, etc.) is placed in a form corresponding to each nozzle 11, and the container 30 and the nozzle 11 are configured to be relatively movable vertically and horizontally. A pressure gauge 14 for measuring the pressure inside the air pipe 13 and a two-way electromagnetic valve 15 as a pressure release valve are further provided in the air pipe 13 that communicates the syringe pump 12 and the nozzle 11. The data processing of the drive means 20, the nozzle 11 and / or the container 30, the pressure gauge 14, and the two-way electromagnetic valve 15 is collectively controlled by a control means (not shown).

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example and a comparative example, this invention is not limited to these examples.

Comparative Example 1
In the liquid dispensing apparatus of FIG. 1, the operation of sucking and discharging the liquid in the container 30 was performed twice with all the two-way solenoid valves 15 closed. The sucked and discharged liquid is a mixed liquid of dimethyl sulfoxide and water (density 1.1 g / mL at 20 ° C.). Specifically, the suction and discharge operation was performed by the following method. Here, the air suction before sucking the liquid and the air discharge after discharging the liquid are performed to discharge the entire amount of the sucked liquid.
(Suction / discharge operation)
Air suction (80 μL; not shown) -After liquid landing, liquid suction (15 μL, liquid suction 1) -After liquid separation, liquid discharge (15 μL, liquid discharge 1) -3 seconds later, air discharge (40 μL, air discharge 1) -After liquid landing, liquid suction (15 μL, liquid suction 2)-After liquid separation, liquid discharge (15 μL, liquid discharge 2)-After 3 seconds, air discharge (40 μL, air discharge 2)
Of the suction and discharge operations, the measured value of the suction amount in the step of liquid suction 2 and the measured value of the discharge amount in the step of liquid discharge 2 were evaluated for each dispenser (combination of the syringe pump 12 and the nozzle 11). The results are shown in FIG. It can be seen that the suction amount and the discharge amount are significantly reduced in one dispenser (No. 4) among the eight dispensers.

  For the dispenser (No. 1) showing the normal suction amount and discharge amount and the dispenser (No. 4) showing the low suction amount and discharge amount in the suction and discharge operation, each dispenser FIG. 3 shows the result of comparing the measured values with the pressure gauge 14 provided. FIG. 3A shows a dispenser No. 1, and FIG. 4 is the result.

  Dispenser No. showing normal suction volume and discharge volume. 1 (FIG. 3A), in the liquid suction 1 step, the pressure suddenly drops to −0.4 kPa or less due to air suction, and the pressure rises back to −0.1 kPa as the liquid enters the nozzle. To do. In the step of liquid discharge 1, the pressure suddenly rises to 0.4 kPa by pushing out the air in the pipe, and after the liquid is discharged from the nozzle, the pressure drops to 0.1 kPa because the tip of the nozzle is opened. . In the process of air discharge 1, the pressure rises to 0 kPa after the peak of pressure rise occurs. The pressure change in the process of liquid suction 2 -liquid discharge 2 -air discharge 2 is equivalent to the pressure change in the process of liquid suction 1 -liquid discharge 1 -air discharge 1.

  On the other hand, dispenser No. showing a low suction amount and discharge amount. 4 (FIG. 3 (b)), the process of liquid suction 1-liquid discharge 1 is almost the same as the pressure change (FIG. 3 (a)) in the dispenser showing the normal suction amount and discharge amount. An abnormal pressure change is shown in the air discharge 1 and subsequent steps. In other words, in the air discharge 1 process, after a waveform in which the pressure rises and falls rapidly occurs, the pressure remains high at 0.4 kPa. The waveform shows a rapid pressure increase that occurs when liquid adhering to the nozzle inner wall by air discharge gathers at the nozzle tip and closes the nozzle, and a rapid pressure drop due to breakage of the nozzle tip by further air discharge. This phenomenon is caused by repeated phenomena, and the high pressure is thought to be because the pressure inside the pipe was stabilized in a positive pressure state by discharging air in a state of being blocked by a liquid film. . The peak of pressure drop due to the liquid suction 2 step is -0.3 kPa, which is a pressure lower than the pressure value (-0.4 kPa) (FIG. 3 (a)) in the dispenser showing the normal suction amount and discharge amount. It can be seen that the degree is insufficient and the time to pressure recovery (-0.1 kPa) is also long. This phenomenon is thought to have led to a decrease in the amount of suction. The pressure after the step of liquid discharge 2 returns to the positive pressure state 0.4 kPa before the step of liquid suction 2. This suggests that the nozzle tip is blocked by the liquid even after the liquid is discharged. In the step of air discharge 2, the liquid film that has blocked the nozzle tip is broken, and the pressure returns to 0 kPa.

Example 1
Based on the result of Comparative Example 1, in this example, after the liquid suction / discharge operation is performed once, before the next liquid suction / discharge operation is performed, the pressure is released by the two-way electromagnetic valve 15 provided in the apparatus of FIG. The operation was performed. Specifically, the suction / discharge operation was performed by the following method. The sucked and discharged liquid is the same as the liquid used in Comparative Example 1. In addition, the air suction amount before sucking the liquid and the air discharge amount after discharging the liquid were increased from the comparative example in order to discharge the entire amount of sucked liquid more completely and the liquid discharge This is because the phenomenon of positive pressure in the nozzle due to the subsequent air discharge is reproduced more frequently.
(Suction / discharge operation)
Air suction (160 μL; not shown)-After liquid landing, liquid suction (15 μL, liquid suction 3)-After liquid separation, liquid discharge (15 μL, liquid discharge 3)-After 5 seconds, air discharge (160 μL, air discharge 3) -After 5 seconds, all the two-way solenoid valves 15 are opened (3 seconds, valve open)-After the two-way solenoid valve 15 is closed, air suction (160 μL, air suction 4)-After liquid landing, liquid suction (15 μL) , Liquid suction 4)-after liquid separation, liquid discharge (15 μL, liquid discharge 4)-after 5 seconds, air discharge (130 μL, air discharge 4)
Of the suction and discharge operations, the measured value of the suction amount in the step of liquid suction 4 and the measured value of the discharge amount in the step of liquid discharge 4 were evaluated for each dispenser (combination of the syringe pump 12 and the nozzle 11). The results are shown in FIG. Of the eight dispensers, there is no dispenser that showed significantly lower suction volume and discharge volume, the suction volume was from 15.0 μL to 15.5 μL, and the discharge volume was from 14.6 μL to 15. The result was within the width of 4 μL.

  In the suction and discharge operation, the dispenser No. 1 and No. FIG. 5 shows the result of comparing the measured values with the pressure gauge 14 provided in each dispenser for 2. FIG. 5A shows a dispenser No. 1, and FIG. The result of 2. Dispenser No. 1 (FIG. 5A) is the same as the pressure fluctuation pattern shown in FIG. 3A except that there is a slight disturbance in pressure fluctuation in the air suction 4 step.

  On the other hand, dispenser No. 2 (FIG. 5B), the pressure value disturbance as shown in FIG. 3B occurs in the steps of air discharge 3 and air discharge 4. However, in this example, after the step of air discharge 3, the pressure release valve (two-way solenoid valve) is opened (valve open) and the pressure returns to 0 kPa. Realizes normal suction and discharge. A negative pressure peak was confirmed during the air suction 4 process (around 21 s). This was because the air was sucked without changing the closed state due to liquid wetting at the nozzle tip even when the solenoid valve was opened, and the pressure suddenly increased. It is thought that it was lowered.

  To summarize the above, the decrease in the liquid suction amount and the discharge amount in the liquid dispensing means provided with the nozzle and the pump is caused by the positive pressure accompanying the liquid blockage to the nozzle in the air discharge step after the liquid discharge. Before installing the pressure relief valve in the air pipe that connects the nozzle and pump, after dispensing the liquid (after discharging the liquid) by the liquid dispensing means, and before dispensing the next liquid (suctioning the liquid) It can be seen that by performing the pressure release by the pressure release valve, the phenomenon of the positive pressure is eliminated, and the problem of a decrease in the liquid suction amount and the discharge amount is solved.

100: Sample suction device 11: Nozzle 12: Syringe pump 13: Air pipe 14: Pressure gauge 15: Two-way solenoid valve 20: Driving means 30: Sample container

Claims (2)

A liquid dispensing means for dispensing a fixed amount of liquid, comprising a nozzle, an air pipe communicating with the nozzle, and a pump for transmitting suction and discharge force to the nozzle through the air pipe;
Drive means for driving the pump;
A liquid dispensing device comprising:
The liquid dispensing apparatus, wherein a pressure release valve is further provided in an air pipe provided in the liquid dispensing unit. The liquid dispensing method using the liquid dispensing apparatus according to claim 1, wherein after the liquid is dispensed by the liquid dispensing means and before the next liquid is dispensed, the pressure relief operation is performed by the pressure relief valve.

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