JPH10123026A - Sample-suction method and sample-suction control apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a gap from being split even when a sample suction speed is increased and to shorten the suction time. SOLUTION: A tapered nozzle 1 which comprises a taper part 7 is used, a cleaning liquid inside the nozzle 1 is sucked by a syringe pump 15 so as to be moved, and a sample is sucked. A gap is formed between the sample and the cleaning liquid. First, the sample is sucked at a suction speed at a critical speed or lower at which the gap is not split when the gap is passed through the taper part 7. Then, when the gap is passed through the taper part 7 and after the sample has arrived at a safe region in which the gap is not split, the suction speed is changed over to the side of a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample suction method and a sample suction control device, and more particularly, to a method using a tapered nozzle having a tapered portion and drawing and moving a liquid injected into the nozzle from a nozzle tip. And a control device applied to the method.

[0002]

2. Description of the Related Art Conventionally, in a sample test, a pipetting operation is performed in which a sample in a test tube is sucked into a nozzle and the sample is discharged to another test tube for inspection. At this time, a dispensing device in which a nozzle and a dispensing pump are connected by a piping system such as a tube is used. In the dispensing device, the suction force generated in the dispensing pump is transmitted to the nozzle via the piping system, and the sample is sucked from the opening at the tip of the nozzle. Hereinafter, a conventional sample suction method will be described by taking a sample suction in a dispensing apparatus as an example.

[0003] As one type of conventional dispensing apparatus, there is one in which a liquid for pressure transmission is injected into a piping system between a nozzle and a dispensing pump. In this conventional device, the liquid in the pipe functions as a medium for transmitting the suction force to the nozzle. That is, when a suction force is generated in the dispensing pump, the liquid in the pipe moves toward the dispensing pump, and as a result, the sample is sucked from the tip of the nozzle.

Further, in this conventional apparatus, generally, FIG.
As shown in (2), a layer of air or the like is formed between the pressure transmitting liquid and the sucked sample in the nozzle. Hereinafter, this layer of air or the like is referred to as a gap. The formation of the gap, for example,
From the state where the liquid for pressure transmission is filled up to the nozzle tip,
This is performed by suctioning air or the like into the nozzle before suctioning the sample. The gap has a function of preventing the liquid for pressure transmission from mixing with the sample.

[0005]

Conventionally, there has been a demand for an improvement in the inspection processing speed. To meet this demand, it is desired to reduce the suction time as much as possible. But simply,
If the suction speed (the amount of suction per unit time) is increased to shorten the suction time, the gap may be split as described below.

A general nozzle has a tapered portion and is tapered. When the sample to be aspirated passes through the reduced diameter portion at the tip, the flow velocity of the sample becomes extremely large. Therefore, when the sample passes through the tapered portion after passing through the reduced diameter portion, it is considered that the sample swirls like a fountain. When the suction speed of the sample is increased, a part of the gap is left behind from the other part due to the action of the fountain-like vortex. As a result, it is considered that the gap is split as shown in FIG.
FIG. 7 shows the case where the gap splits into two,
One gap is formed in the middle of the sample.

[0007] When a sample is discharged in a state in which a gap has been split, the dispensed amount becomes smaller than the specified amount in accordance with the volume of the gap that has been split and left behind. Therefore,
In order to dispense a specified amount of sample, it is necessary to prevent the occurrence of gap splitting. In the prior art, the suction speed of the sample has been limited to a speed lower than a limit speed at which no gap split occurs at the tapered portion. Therefore, it has been difficult to shorten the sample suction time.

In particular, when the inner diameter difference between the reduced diameter portion and the normal portion of the nozzle is large, the above-mentioned limit speed is low. Since the sample must be sucked at a speed lower than this limit speed, there is a problem that the suction time becomes longer, and as a result, the number of processes per unit time is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sample suction method and a sample suction control apparatus which can solve the above-mentioned problems and can reduce the sample suction time without causing a gap split. . Further, it is an object of the present invention to provide a sample suction method and a sample suction control device in which the suction time does not become long even when the inner diameter difference before and after the tapered portion of the nozzle is large.

[0010]

According to the present invention, a tapered nozzle having a tapered portion is used, and the liquid in the nozzle injected into the nozzle is drawn and moved to suck a sample from the tip of the nozzle. A sample suction method performed while interposing a gas layer between the liquid in the nozzle and the sample,
A low-speed suction step of sucking a sample at a suction speed equal to or lower than a limit speed at which the gas layer does not split when passing through the tapered portion, and after the gas layer passes through the tapered portion, switching the suction speed to a high speed side. A high-speed suction step of sucking the sample.

Here, the gas layer is a gap of air or the like described in the prior art. According to the present invention, when the gas layer passes through the tapered portion, which is a location that is easily split,
The sample is sucked at a suction speed less than the limit speed at which the gas layer does not split. Then, after the gas layer has passed through the tapered portion, the suction speed is switched to the high speed side to suck the sample. Therefore, the time for aspirating the sample is reduced without causing the gas layer to split.

In particular, when the difference in inner diameter before and after the tapered portion of the nozzle is large and the limit speed at which the gas layer does not split is low, the suction speed of only a part of the suction step may be set low. Therefore, it is possible to prevent the suction time from being lengthened due to the limitation of the limit speed.

In one aspect of the present invention, in the high-speed suction step, the suction speed is switched at a position where the lower surface of the gas layer has risen a predetermined distance above the tapered portion. The effect of the factor of the gas layer splitting may remain even when the gas layer passes through the tapered layer. In the above configuration, the speed is switched after reaching the safety region where the influence of the splitting factor of the gas layer is eliminated, so that the splitting of the gas layer can be reliably prevented.

Further, the present invention uses a tapered nozzle having a tapered portion, and draws and moves the liquid in the nozzle injected into the nozzle, thereby sucking a sample from the nozzle tip,
This suction is a sample suction control device in which a gas layer is interposed between the liquid in the nozzle and the sample, and the suction amount of the sample is controlled by controlling the moving amount and moving speed of the drawing movement of the liquid in the nozzle. Control means for adjusting the suction speed, the control means comprising: a low-speed suction means for sucking a sample at a suction speed less than a limit speed at which the gas layer does not split when the gas layer passes through the tapered portion; and And high-speed suction means for switching the suction speed to a high-speed side after passing through the tapered portion and sucking the sample. With this configuration,
The same operation and effect as those of the sample suction method described above can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a sample suction method and a sample suction control device according to an embodiment of the present invention will be described with reference to the drawings. Here, a case where the present invention is applied to a dispensing apparatus having the configuration shown in FIG. 1 will be described. This dispensing apparatus is provided on a base (not shown), aspirates a sample from a dispensing source test tube placed on the base to a nozzle, and moves the nozzle to a dispensing destination test tube. Discharge the sample.

In FIG. 1, a nozzle 1 is a non-disposable type nozzle made of stainless steel. Nozzle 1
Has a sample holding section 3 having an inner diameter of about 2 mm, and a suction section 5 having an inner diameter of about 0.5 mm and a length of about 6 mm at the tip. Then, the sample holding unit 3 and the suction unit 5 are connected to a conical tapered portion 7.
It is connected by. In the nozzle 1, a sample for dispensing can be sucked up to several hundred μl. Nozzle 1 is XYZ
By the robot 10, a sample suction position, a sample discharge position,
Move to nozzle cleaning position. The nozzle 1 is communicated with the switching valve 11 by a polymer tube 13. The inner diameter of the tube 13 is about 2 mm.

The switching valve 11 is further connected to a syringe pump 15 and a tube 17, and is connected to a cleaning liquid tank 19 and a tube 21. The tube 17 and the tube 21 are both made of polymer and have an inner diameter of about 2 mm. The switching valve 11 performs a switching operation by being driven by a valve motor 12.
Then, the nozzle 1 communicates with the syringe pump 15, and the syringe pump 15 communicates with the cleaning liquid tank 19.

The syringe pump 15 is a cylindrical syringe 2
3, a piston 25 is inserted into the syringe 23, and a syringe chamber 27 is formed by the syringe 23 and the piston 25.
Are formed. The syringe 23 is connected to the tube 17 at an opening 29 on the end face. The piston 25 is connected to the syringe 23 by the pump motor 31.
It is driven to reciprocate within. In the syringe room 27,
A cleaning liquid is injected as described below. When the piston 25 moves in the direction of the opening 29, the cleaning liquid is pushed out of the opening 29, and when the piston 25 moves in the direction opposite to the opening 29, the cleaning liquid is sucked. Hereinafter, the former piston movement is referred to as push-out movement, and the latter piston movement is referred to as retracting movement.

The cleaning liquid tank 19 stores a cleaning liquid. In this embodiment, the cleaning liquid functions as a liquid for pressure transmission described in the related art, in addition to functioning as a liquid for cleaning nozzles and the like. The cleaning liquid is supplied to the entire dispensing device by the switching operation of the switching valve 11 and the driving of the syringe pump 15.

FIG. 2 is a block diagram showing a configuration of a control system for driving the nozzle 1, the switching valve 11, and the syringe pump 15. In the figure, a control unit 35 is mainly composed of a computer,
In 5, setting conditions such as the dispensing amount, the number of dispensing processes, and the arrangement of test tubes are input. Further, the control unit 35 is connected to a liquid level detector 39 that detects a liquid level position of the sample in the test tube. The control unit 35 drives the XYZ robot 10 and the valve motor 12 by outputting a drive signal according to the input setting conditions. Further, the control unit 35 controls the driving of the pump motor 31 to adjust the moving amount and the moving speed of the piston 25 of the syringe pump 15. At this time, the control unit 35 adjusts the moving speed of the piston 25 by changing the pulse rate of the drive signal supplied to the pump motor 31.

Next, the operation of the dispensing apparatus will be described separately for "sample suction", "sample discharge" and "washing".

[Specimen Suction] In this case, a sample is sucked into the nozzle 1 from the dispensing source test tube placed on the base. FIG.
Is an enlarged view of the nozzle 1 and the test tube, and shows a suction method of the present apparatus in a time series. At the start of suction, the nozzle 1 is moved by the XYZ robot 10 above the dispensing source test tube. Further, the switching valve 11 is connected to the nozzle 1
And the syringe pump 15 are communicated. Then, the piston 25 of the syringe pump 15 is at a predetermined start position in the syringe. The syringe chamber 27, the tubes 17, 13 and the nozzle 1 are filled with a cleaning liquid. At this time, the cleaning liquid is filled up to the tip of the nozzle 1 as shown in FIG.

First, the piston 25 is pulled and moved in a state where the nozzle port 9 is not inserted into the sample in the test tube. The volume of the syringe chamber 27 increases in response to the movement of the piston 25, and the amount of cleaning liquid corresponding to the change in the volume moves from the nozzle 1 to the syringe pump 15. By the movement of the cleaning liquid, air is sucked from the nozzle port 9 as shown in FIG.

Next, the nozzle 1 is moved downward and inserted into the sample. At this time, the liquid level detector 39 in FIG. 2 detects the liquid level position of the sample and inputs the same to the control unit 35. Control unit 35
Controls the XYZ robot 10 based on the position of the liquid level. Then, the XYZ robot 10 moves about 1-2
The nozzle 1 is inserted to a depth of about mm, and the nozzle 1 is held in this state. FIG. 3C shows the state at this time.

Next, the piston 25 is further retracted and moved. The cleaning liquid moves toward the syringe pump 15 in accordance with the movement of the piston, and the portion of the air previously sucked has a negative pressure. Then, the sample is sucked from the nozzle port 9 by the action of the negative pressure.

FIG. 4 shows the setting of the sample suction speed. The horizontal axis indicates the position of the lower surface of the gap (that is, the upper surface of the sample to be sucked) with respect to the nozzle tip, and the vertical axis indicates the sample suction speed. Speed.

In FIG. 4, positions A and B are positions where the tapered portion 7 of the nozzle 1 starts and ends, respectively. The position C is a position that is a predetermined distance after the end of the tapered portion. The suction speed is set to Va from the start of the suction of the sample until the lower surface of the gap reaches the position C. The suction speed Va is set lower than the limit speed at which the gap does not split when the gap passes through the tapered portion 7. Note that this limit speed is determined by the suction unit 5.
The value varies depending on the inner diameter of the sample, the flow rate of the sample in the suction section 5, the taper angle of the tapered section 7, and the like.

When the lower surface of the gap reaches the position C,
As shown in FIG. 4, the suction speed is switched to the high speed side and becomes Vb. In FIG. 4, the area on the retraction movement side from the position C is in a safe area where there is no influence of a vortex (see FIG. 7) generated on the upper surface of the sample and causing a gap split. Therefore, even if the suction speed is increased, no gap split occurs.
After switching the suction speed, the suction speed Vb is maintained, and the retraction movement of the piston 25 is continued until a predetermined suction amount is sucked. FIG. 3D shows a state in which the lower surface of the gap is at the position C and the speed is switched. FIG.
(E) shows a state where the sample is sucked at the suction speed Vb and the suction is completed.

The control unit 35 moves the piston 25 in accordance with the settings shown in FIG. That is, at the beginning of suction,
The moving speed of the piston 25 is set so that the suction speed Va is obtained. At the time of speed switching, the suction speeds Vb and V
The pulse rate of the drive signal is raised according to the speed difference a, and the moving speed of the piston 25 is switched.

[Specimen Discharge] Here, the sample sucked by the nozzle 1 is discharged to a test tube of a dispensing destination. XYZ robot 1
0 moves the nozzle 1 to the dispensing test tube, inserts the tip of the nozzle 1 into the test tube, and holds the nozzle 1 with the nozzle port 9 in the air. Then, the piston 25 of the syringe pump 15 is driven by the pump motor 31 and pushes out. By this pushing movement, the volume of the syringe chamber 27 is reduced corresponding to the dispensed amount. As a result, the washing liquid corresponding to the dispensed amount moves toward the nozzle 1 and the sample is discharged from the nozzle port 9 into the test tube.

After the “washing” of the sample is completed, the XYZ robot 10 moves the nozzle 1 to a washing position where a washing tank is provided. Then, the piston 25 of the syringe pump 15 is pushed out and moved, and several hundred μl of the cleaning liquid is discharged to the cleaning tank.
At this time, the cleaning liquid is also applied to the outside of the nozzle 1 at the same time. Thereby, the inner and outer surfaces of the nozzle 1 are cleaned.

After the washing is completed, the washing liquid is supplied to the syringe pump 15 as appropriate. In this replenishment, the switching valve 11 performs a switching operation, and the syringe pump 15 and the cleaning liquid tank 19 are switched.
To communicate. When the piston 25 retracts, the cleaning liquid in the cleaning tank 19 is supplied to the syringe pump 1.
Move to 5.

The embodiment of the present invention has been described above. In the sample suction according to the present embodiment, the suction speed is set to a low speed (Va) in a section in which gap splitting easily occurs until the upper surface of the sample reaches the position C in FIG. Then, after the upper surface of the sample has passed the position C, the suction speed is switched to the high speed side (Vb).

FIG. 5 shows how the suction speed of the sample changes over time. In the same drawing, a change in the suction speed when the same amount of sample is suctioned by the suction method of the present embodiment and the conventional suction method is shown in comparison. In the prior art, as shown by a dotted line, the suction speed is set so as to change to a trapezoidal shape. On the other hand, in the present embodiment,
As shown by the solid line, the suction speed is switched in two stages, and suction is performed at a lower suction speed (Va) than the conventional one until time tc when the lower surface of the gap reaches the speed switching point (position C in FIG. 4). Therefore, the occurrence of gap splitting is more reliably prevented than before. Then, at time tc, the suction speed is rapidly switched, and becomes significantly higher than in the past (V
b). As a result, the total suction time is greatly reduced as compared with the conventional case. As described above, according to the present embodiment, the occurrence of gap splitting can be reliably prevented, and the entire suction time can be reduced.

In particular, in this embodiment, the difference between the inner diameter (2 mm) of the sample holder 3 and the inner diameter (0.5 mm) of the suction unit 5 is large. Therefore, the limit speed of the splitting of the gap in the tapered portion 7 is low. If the suction is performed at a constant speed below the limit speed as in the related art, the suction time becomes longer, and the number of processes per unit time is reduced. However, in the present embodiment, since only the suction speed at the beginning of suction is set low by switching the suction speed as shown in FIG. 4, the suction time is prevented from becoming long.

When the suction amount is particularly large, a large amount of the sample is still sucked after the upper surface of the sample has passed the tapered portion 7. Therefore, the suction time is greatly reduced by the speed switching of the present embodiment.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a dispensing device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control system for driving a nozzle, a switching valve, and a syringe pump of the apparatus of FIG.

FIG. 3 is an enlarged view of a nozzle showing a dispensing operation of the apparatus of FIG. 1 in chronological order.

FIG. 4 is an explanatory diagram showing setting of a suction speed at the time of sucking a sample in the apparatus of FIG. 1;

FIG. 5 is an explanatory diagram showing a time change of a sample suction / suction speed in the apparatus of FIG. 1;

FIG. 6 is a cross-sectional view of a nozzle showing a state where a sample is sucked.

FIG. 7 is a cross-sectional view of the nozzle showing a state in which a gap split has occurred in the nozzle.

[Explanation of symbols]

1 nozzle, 3 sample holding section, 5 suction section, 7 taper section, 9 nozzle port, 10 XYZ robot, 11 switching valve, 12 valve motor, 13, 17, 21 tube,
15 syringe pump, 19 cleaning liquid tank, 23 syringe, 25 piston, 27 syringe chamber, 31 pump motor

Claims (3)

[Claims] 1. A tapered nozzle having a tapered portion,
A sample is sucked from the nozzle tip by drawing and moving the liquid in the nozzle injected into the nozzle, and this suction is a sample suction method performed while a gas layer is interposed between the liquid in the nozzle and the sample, A low-speed suction step of sucking a sample at a suction speed equal to or lower than a limit speed at which the gas layer does not split when passing through the tapered portion, and after the gas layer passes through the tapered portion, switching the suction speed to a high speed side. A high-speed suction step of sucking a sample, comprising: 2. The method according to claim 1, wherein in the high-speed suction step, the suction speed is switched at a position where the lower surface of the gas layer rises by a predetermined distance from the tapered portion. Method. 3. A tapered nozzle having a tapered portion,
A sample suction control device which draws and moves the liquid in the nozzle injected into the nozzle to suction the sample from the nozzle tip, and the suction is performed while a gas layer is interposed between the liquid in the nozzle and the sample. A control unit that adjusts a suction amount and a suction speed of the sample by controlling a movement amount and a movement speed of the drawing movement of the liquid in the nozzle, wherein the control unit causes the gas layer to pass through the tapered portion. A low-speed suction means for sucking the sample at a suction speed equal to or lower than the limit speed that does not split, A sample suction control device characterized by including: