JPH0634497A - Dispensing device - Google Patents

Abstract

PURPOSE:To obtain a continuous liquid dispensing device which can prevent the remaining of a liquid sample at the front end section of its chip. CONSTITUTION:An inlet valve 31 is installed to a pipeline system for sucking a reagent into a syringe pump 10 and an outlet valve 33 is installed to a pipeline system through which a liquid sample is discharged from the pump 10. By inverting the pump 10 upon completing the discharging operation under such a condition, the pump 10 is made to continuously perform dispensing operations while the formation of a liquid drop is prevented at the front end section 14a of a chip 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispensing device, and more particularly to an improvement of a dispensing device which performs a dispensing operation with high accuracy without bringing the tip end portion of the tip into contact with the liquid surface.

[0002]

2. Description of the Related Art Dispensing devices can greatly improve test efficiency by automating individual operations, and are used, for example, to greatly omit blood tests.

The structure of such a dispensing device is shown in FIG.
And is composed of a syringe pump 10, a pipe system 12 connected to the syringe pump 10, and a chip 14 installed at a tip portion of the pipe system 12. There is. Here, the syringe pump 10 is used as a pump because it is suitable for dispensing a small amount of liquid sample.
Is composed of a cylinder 10a and a piston 10b. A drive system 16 composed of a motor or the like is installed in the piston 10b, and the piston 10b is moved up and down by the drive system 16 so that the liquid sample stored in the syringe pump 10 is It is adapted to be dripped from the tip portion 14 a of the chip 14 via the piping system 12.

In order to maintain good measurement accuracy, it is necessary for both sample dispensing and reagent dispensing to accurately drop the set amount into the sample tube. However, due to the material and shape of the tip 14 and the property of the liquid sample used for dispensing, liquid droplets of different sizes may be generated at the tip portion 14a of the tip 14, and the dispensed amount may vary.

FIG. 7 is a graph showing the relationship between the time when the liquid sample is ejected from the tip 14 and the pressure inside the tip 14 by the above-mentioned conventional apparatus, P ₀
Represents atmospheric pressure. The period indicated by α in FIG. 7 is a region showing the pressure change in the first half of the discharge operation, β shows the pressure change in the latter half of the discharge operation, and γ shows the pressure change after the end of the discharge operation. . As shown in FIG. 7, in the first half period α of the ejection operation, the tip 14 reaches the pressure at which the liquid sample is ejected from the tip 14 a of the tip 14.
The internal pressure rises sharply. During the first half period α of the discharging operation, the liquid sample is not discharged from the tip portion 14a. Then, in the latter half period β of the ejection operation,
From the tip 14a to the pressure at which the liquid sample is discharged, the tip 1
Since the pressure inside 4 has risen, the liquid sample is discharged and dropped from the tip portion 14a. During the latter half period β of the discharge operation, the piston 1 of the syringe pump 10
Since the pressure inside the chip 14 increases with the moving speed of 0b, a rapid increase as in the period α does not occur.

When the discharging operation is completed, the chip 1
Although the pressure inside 4 decreases, the pressure inside the chip 14 does not decrease sharply and gradually returns to atmospheric pressure P ₀ as indicated by the region γ in FIG. 7. In this way, since the inside of the tip 14 gradually returns to atmospheric pressure, the area γ
In FIG. 8A, as shown in FIG.
A liquid droplet 18 is generated at the tip portion 14a of the.

[0007]

The presence of the liquid ball 18 has a fatal adverse effect on the accuracy of analysis when, for example, a large amount of reagent is dropped on different samples in the same amount for analysis. May affect. That is, when the reagent is desired to be dropped in several times, liquid droplets of different sizes are generated at the tip end portion of the chip, which causes variations in the amount of the reagent dropped once. Such a state is shown in FIGS. 8 (a) and 8 (b), and a liquid ball 18 is generated at the tip portion 14a, and when the reagent has a small surface tension, the liquid ball of FIG. Like the tip 1
It will remain on the tip portion 14a as it wraps around the outside of 4a. Such a residue may have a wall thickness of 0.5, for example.
5-10 μm when using a polypropylene chip with an inner diameter of 0.5 mm and an inner diameter of 0.5 mm (that is, an outer diameter of 1.5 mm)
1 will remain, which will have a significant impact on accuracy if a 50 μl drop is desired.

Further, as described at the beginning, the dispensing device is used for labor saving. Therefore, it is necessary to improve the inspection efficiency as well as the accuracy. For this purpose, it is necessary to automate the suction / discharge cycle of the liquid sample with a simple configuration.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid dispensing apparatus which performs a continuous dispensing operation with high accuracy.

[0010]

In order to solve the above problems, in a liquid dispensing apparatus according to the present invention, a syringe pump comprising a piston and a cylinder, and a liquid sample suction / discharge port of this syringe pump. A pipe system connected to the pipe system, a chip installed at the tip of the pipe system for dropping a liquid sample, and a drive system for moving the piston of the syringe pump. In a dispensing device that performs a dispensing operation by dropping a sample, a piping system connected to the liquid sample suction / discharge port of the syringe pump is branched into two branches, and one of these branches is suctioned. Valve is installed, the discharge valve is installed in the other branch,
The dispensing device further includes means for causing the tip to perform a predetermined suction operation at the time of switching from discharge to suction, sucking the liquid sample into the syringe pump, and then discharging the liquid sample from the syringe pump. After a fixed amount is dropped,
Dispense the liquid sample continuously by pulling back the piston in the syringe pump, performing a predetermined suction operation from the tip of the tip, and then again sucking the liquid sample into the syringe pump. It is characterized by

[0011]

In the liquid dispensing apparatus according to the present invention constructed as described above, when the piston in the syringe pump is pulled back, the liquid sample is sucked into the syringe pump. At this time, the suction valve installed in the piping system connected to the suction / exhaust port of the syringe pump is opened and the discharge valve is closed. Therefore, the liquid sample is sucked from one branch in which the suction valve is installed, out of the two branching piping systems. Normally, a liquid sample storage bottle (reagent bottle) is connected to the branch where the suction valve is installed, so when the piston in the syringe pump is pulled, the liquid sample is sucked from the reagent bottle into the syringe pump. The Rukoto.

When the piston in the syringe pump is pushed up, the liquid sample is discharged from the syringe pump. At this time, the suction valve installed in the piping system connected to the suction / discharge port of the syringe pump is closed and the discharge valve is opened. Therefore, the liquid sample is discharged from one branch, in which the discharge valve is installed, of the piping system branched into two branches. Normally, the tip is connected to the branch where the discharge valve is installed, and the liquid sample is discharged from this tip, so when the piston in the syringe pump is pushed, the liquid sample is discharged from the syringe pump. Then, the liquid sample is discharged from the tip of the chip.

Therefore, when the piston of the syringe pump is pulled, the liquid sample is always sucked from the reagent bottle into the syringe pump, and when the piston of the syringe pump is pushed, the liquid sample is always discharged from the tip of the tip. It will be. That is, by repeatedly pushing and pulling the piston in the syringe pump, the suction of the liquid sample from the reagent bottle and the discharge of the liquid sample from the tip of the tip are continuously performed. Then, when the piston is pulled after the piston is pushed, since the suction operation is temporarily performed at the tip end portion of the tip, at the end of the dropping operation,
The liquid sample that may remain at the tip of the chip is cut off and dropped. Therefore, the liquid sample does not remain at the tip of the tip, and continuous dispensing can be performed with high accuracy.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the principle on which the dispensing apparatus according to the present invention is predicated. The same components as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

A characteristic of the dispensing device shown in FIG. 1 is that the piston 10b of the syringe pump 10 performs a reverse operation at the end of the dropping operation. Specifically, the motor (driving system) 21 that is installed on the piston 10b and moves the piston 10b in the up-and-down direction was performing the dropping operation by the forward rotation, but the reverse operation is performed when the dropping operation is completed. In this case, the syringe pump 10 as a whole performs the suction operation at the end of the dropping operation.

FIG. 2 shows a pressure change inside the tip 14 of the dispensing apparatus of FIG. 1 and an operation map of the motor 21. As shown in FIG. 2, the operation of the motor 21 is shown. By reversing, the suction operation is performed, and the pressure inside the piping system 12 sharply decreases at the end of discharge. The operation of the motor 21 is set to stop when a pressure drop below the atmospheric pressure P ₀ occurs.

Here, as can be seen by comparing the regions γ of FIGS. 7 and 2, in the conventional device shown in FIG. 7, the pressure inside the tip 14 gradually decreases even after the ejection operation is completed. On the other hand, in the dispensing device of the present embodiment, the pressure inside the tip 14 sharply drops after the discharging operation is completed. In addition,
The liquid sample is not discharged from the tip portion 14a of the tip 14, and the piping system 12 is used until the pressure at which the liquid sample is discharged from the tip portion 14a.
The period α of the first half of the discharge operation when the internal pressure rises sharply,
The liquid sample is discharged from the tip portion 14a to cause dripping, and the pressure β inside the chip 14 increases with the moving speed of the piston 10b. The period β in the latter half of the discharging operation is the same as that of the conventional device shown in FIG. is there.

In the dispensing apparatus according to the present embodiment, since the piston 10b is rotated in the reverse direction just before the dropping of the predetermined amount of the liquid sample is completed, as shown in FIG. The liquid sample 23 in the last portion of the predetermined amount of 14a is dropped as it is due to the inertial force of itself, and a predetermined space 25 is formed in the tip portion 14a as shown in FIG. 3 (b). Will be done. In this way, the downward movement of the liquid is rapidly raised by the reverse movement of the piston 10b, so that the inertia of the liquid cuts and drops a predetermined amount of the liquid sample at the last portion of the tip portion and drops it. In the dispensing device according to the present embodiment, liquid droplets do not remain on the tip portion 14a.

The principle of the dispensing apparatus according to this embodiment is as follows:
When liquid drops are formed, liquid inertia + liquid drop weight +
Although the equation of water pressure = surface tension of liquid droplet formation is established, it is almost impossible to control the weight and water pressure of the liquid droplet (water pressure inside the tip applied to the tip portion 14a). However, since the inertial force of the liquid can be easily controlled by controlling the motor (driving system) 21, in the present embodiment, the tip 14a is abruptly reversed by reversing the movement direction of the liquid. It is designed to prevent the formation of liquid drops.

By the way, in the dispensing, a sample dispensing for dispensing the sample separated from the sample into the sample tube and a reagent dispensing for dispensing a predetermined amount of reagent into the sample dispensed in the sample tube, respectively. There is a note.

Here, in the sample dispensing, since the specimens are different from each other, it is necessary to prevent the mixing or mixing of the samples in order to improve the measurement accuracy, so most of the chips 14 are disposable. It has become so. At present, a material such as polypropylene is often used in many of the disposable tips 14, but the tip portions 14a are not always uniform. For example, when the tip 14a is chipped or burred, the liquid sample is likely to remain on the tip 14a. Further, the liquid sample used for the dispensing is usually mixed with a surfactant in order to prevent the liquid sample from remaining in the piping system or the tip 14. Therefore, the liquid sample is more likely to travel from the tip of the chip to the outer wall of the tip portion 14a than in a normal liquid.

However, in the dispensing apparatus shown in FIG. 1, when the predetermined amount of liquid sample is dropped, the pressure inside the tip 14 is drastically reduced to cut off the liquid sample at the tip portion 14a. In addition to preventing the generation of liquid droplets, the tip 14a of the liquid sample can be used even when the tip of the disposable tip is chipped or burr, or when the liquid sample is mixed with a surfactant. It is possible to prevent the residue from remaining in the sample, and regardless of whether it is sample dispensing or reagent dispensing,
The set amount can be accurately dropped into the sample tube, and the dispensing measurement accuracy can be kept good.

FIG. 4 is a diagram showing a preferred embodiment of the dispensing apparatus according to the present invention.

The characteristic feature of the dispensing apparatus according to the present embodiment is that the piping system connected to the suction / discharge port 10c of the syringe pump 10 branches into two branches, and the suction valve 31 and the discharge valve 33 are provided here. It is installed, and when the piston 10b of the syringe pump 10 is lowered and the suction operation is performed,
The reagent comes to be sucked into the syringe pump 10 via the suction valve 31. At this time, since the discharge valve 33 is in the closed state, suction is not performed from the tip of the tip 14.

On the other hand, the piston 10 of the syringe pump 10
When b is raised and the discharge operation of the syringe pump 10 is performed, the tip 14 is discharged through the discharge valve 33 which is in the open state.
The reagent is discharged from the tip portion 14a of the.
At this time, since the suction valve 31 is closed, the reagent in the syringe pump 10 is not discharged to the reagent bottle 35. Then, by repeating this operation, the continuous dispensing operation is performed while preventing the generation of the liquid droplets at the tip portion 14a.

Here, when the device switches from discharge to suction, the piston 10b is suddenly pulled back. If the suction is temporarily performed from the tip portion 14a at this time, it is possible to prevent the reagent from remaining on the tip portion 14a and improve the dispensing accuracy, as described in the premise. . In the present embodiment, the size of the discharge valve 33 is made larger than that of the intake valve 31, and the difference between the characteristics of the two valves causes
When the device switches from discharge to suction, suction is temporarily performed at the tip portion 14a.

The operation of the syringe pump 10 will be described in detail with reference to FIG. First, when the piston 10b is lowered and the suction operation is performed (step A), the reagent is sucked from the reagent bottle 35 into the syringe pump 10, and a predetermined amount of the reagent is sucked into the syringe pump 10. Next, the sample tube is carried to a predetermined position below the chip 14 (step B). Then, the discharging operation is performed (step C). Here, the tip portion 14a
In order to prevent the generation of the liquid droplets in (3), the reverse operation is immediately performed at the time (P) when the discharging operation is completed, which prevents the liquid sample from remaining at the tip portion of the tip 14. Then, after the temporary suction at the tip portion 14a is completed, the suction operation from the reagent bottle 35 is continuously performed and a predetermined amount of the reagent is sucked into the syringe pump 10 (step D). In this way, first, suction is performed (step A), after a predetermined time has elapsed (step B), discharge operation is performed (step C), reverse operation is performed at the end of the discharge operation (time point P), and suction operation is continued. Then syringe pump 1
Aspirate the reagent into 0 (step D). By repeating such operations, the dispensing apparatus according to the present embodiment operates in a cycle such as reagent suction, reagent discharge, liquid droplet generation prevention, and subsequent reagent suction, so that continuous operation is possible. The dispensing operation can be performed with high accuracy.

In the dispensing apparatus according to this embodiment, a pressure sensor (not shown) is installed in the pipe system 12 near the tip 14, and the motor (drive system) 21 of the motor 21 is driven based on the information from the pressure sensor. The operation may be controlled. In this case, the motor (driving system) 21 can be accurately controlled based on the situation of individual dispensing.

[0029]

As described above, in the dispensing apparatus according to the present invention, regardless of the type of liquid sample or the type of chip used, the liquid sample is prevented from remaining at the tip portion of the chip, The dispensing operation can be performed continuously. As a result, the efficiency of the dispensing operation can be improved while preventing the accuracy from deteriorating due to the liquid sample remaining on the chip.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a principle that is a premise for explaining an embodiment of a dispensing device according to the present invention.

FIG. 2 is a diagram for explaining the operation of the dispensing device in FIG.

FIG. 3 is a diagram illustrating a state of a tip end portion of the tip during operation of the dispensing device of FIG.

FIG. 4 is a diagram showing a configuration of a dispensing device according to a preferred embodiment of the present invention.

5 is a schematic diagram showing the operation of the syringe pump of the dispensing device of FIG.

FIG. 6 is a diagram showing a basic configuration of a conventional dispensing device.

FIG. 7 is a diagram illustrating a pressure change inside a tip of a conventional dispensing device.

FIG. 8 is a diagram illustrating liquid droplet generation at a tip end portion of a conventional dispensing device.

[Explanation of symbols]

 10 Syringe Pump 10a Cylinder 10b Piston 10c Suction / Discharge Port 12 Piping System 14 Tip 14a Tip 16 Drive System 18 Liquid Ball 21 Motor 23 Liquid Sample 25 Space 33 Discharge Valve 31 Intake Valve

Claims (1)

[Claims] 1. A syringe pump comprising a piston and a cylinder, a pipe system connected to a liquid sample inlet / outlet of the syringe pump, and a chip installed at the tip of the pipe system for dropping the liquid sample. A drive system for moving the piston of the syringe pump, and in a dispensing device that performs a dispensing operation by dropping a liquid sample from the tip of the tip, to the suction / discharge port of the liquid sample of the syringe pump. The connected pipe system is branched into two branches, one of which has a suction valve and the other has a discharge valve. The chip is provided with a means for performing a predetermined suction operation when switching to suction, and after sucking the liquid sample into the syringe pump, the liquid sample is discharged from the syringe pump, and a predetermined amount of the liquid sample is dropped. After that, by pulling back the piston in the syringe pump, performing a predetermined suction operation from the tip of the tip, and then repeating the cycle of sucking the liquid sample into the syringe pump again, the liquid sample is continuously separated. Dispensing device characterized by performing pouring.