JPH0562690B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a device for quantitatively extracting a minute amount of a sample, reagent, etc.

(Background of the Invention) Various analytical methods for detecting trace substances in body fluids have been proposed in the fields of biology, medicine, etc. Systems and devices that perform this have also been provided. One common problem with such systems and devices is the need to strictly control the amount of samples and reagents added to the reaction chamber, etc., and at the same time to prevent contamination between samples. For this reason, it has been widely used in pipettes using high-precision, disposable tips, such as micropipettes. With such a micropipette, the tip of the pipette must be replaced for each sample.
To prevent contamination between samples, the sample is sucked up into the chip using air pressure and weighed.

The above-mentioned problem of the need for strict control of the amount of samples, reagents, etc. added is due to variations in the amount of samples added, for example, in the immunoreaction measurement method to which the present invention is preferably applied.
The problem is how it affects the measurement results. In addition, the concentration ratio of trace components contained in biological samples and measured by immunoreaction assay varies from 10 4 to 10 ⁴ depending on the sample.
Since the range of values can be as wide as 10 ⁶ times, it is desirable to use disposable chips to prevent sample-to-sample contamination. By the way, even when using the above-mentioned micropipette etc. to take out a fixed amount of a sample etc. from a predetermined storage container, there are problems that need to be further improved in order to detect trace amounts of target substances with high precision. discovered by the inventor. This is because when inserting a pipette into a sample container and aspirating a sample, even if the negative pressure of the suction is strictly controlled, the depth at which the pipette nozzle is immersed into the sample varies depending on the volume of the sample. This is explained as a problem in that this tends to occur, and this can lead to errors that cannot be ignored when taking out a fixed amount. This problem also occurs when the sample container has a small diameter, and the liquid level is inclined (meniscus) due to the influence of surface tension, or the container itself is inclined.

From this point of view, some proposals have been made to attach a sensor to detect the liquid level to the liquid quantitative extraction device, but electrode-type sensors have problems with contamination, and general non-contact optical sensors have problems with contamination. However, it cannot be expected to have an accuracy of more than a few millimeters, and it also has the disadvantage of not being able to handle cloudy liquid or tilted liquid levels. An error of several millimeters in immersion results in a variation of several to 10% when taking out 5 μm of liquid from a 200 μm container, for example.

(Object of the Invention) The present invention has been made from the above-mentioned viewpoints, and its purpose is to provide a liquid quantitative extraction device that can control the amount taken out with high precision when taking out a small amount of liquid quantitatively. It is in a place where we provide.

Another object of the present invention is to provide a liquid quantitative extraction device that can be suitably applied as part of an automatic analyzer, particularly an automatic analyzer for measuring immune reactions.

(Summary of the Invention) The liquid quantitative extraction device according to the present invention, which has been made to achieve the above object, is characterized by a pipette having a lower end nozzle for sucking and discharging the liquid, and a pipette that is moved downward to take out the lower end nozzle. A pipette downward movement control mechanism for immersing the pipette in the target liquid;
The pipette is equipped with a sensor that projects light onto the liquid surface while approaching the liquid surface in a downward motion and detects the reflected light from the liquid surface, and determines the point at which the pipette stops moving downward based on the detection information of the sensor. The sensor is a spot-type reflective sensor having a light convergence optical element focused at a position a fixed length apart from the bottom, and the maximum light intensity of the input reflected light is determined by the sensor. The present invention is characterized in that a point is used as determination information for the pipette downward movement stop point.

The pipette downward movement control mechanism can be configured, for example, as a pedestal that supports a pipette member supporting device so as to be movable up and down, and which is moved up and down by a pulse motor via a cam mechanism or the like.

The spot-type reflective sensor used in the present invention includes, for example, a light-emitting section and a light-receiving section that allow the light source light and reflected light to go in and out through a convex lens, which is a light-converging optical element, or a light-emitting section with the convex lens. , a type in which the light-receiving section is made independent and arranged symmetrically through the focal point may be adopted as appropriate.

The maximum light intensity point of the input reflected light detected by this reflective sensor can be detected, for example, by converting the input reflected light into an electrical signal and detecting the high peak of this electrical signal.

According to a sensor with such a configuration, the maximum light intensity point of the input reflected light appears when the liquid level reaches the focal position, regardless of the inclination of the liquid surface, the dirtiness of the liquid, etc. By determining the stopping point of the pipette's downward movement, it becomes possible to strictly control the immersion depth of the pipette's lower end nozzle into the liquid.

The present invention is preferably applied to various analysis and measuring devices that generally require the quantitative extraction of liquids of approximately 1000 μm or less, and is particularly applicable to extremely minute amounts of liquids of 100 μm or less such as immunoreaction measurements and biochemical reaction measurements. It is suitably used for taking out. The target liquid may be a sample, a reagent, or the like.

In the present invention, the means for moving the sensor downwardly toward the target liquid level may be integrally assembled with the pedestal supporting the pipette, or the pipette supporting pedestal may be independently attached to the sensor pedestal and its pedestal. A lowering mechanism may be provided. It is desirable for the liquid level detected by the sensor to correspond as much as possible to the horizontal position where the pipette lower end nozzle is immersed in the liquid level for highly accurate control of the amount of liquid taken out.

(Embodiments of the Invention) The present invention will be described below based on embodiments shown in the drawings.

Fig. 1 is a diagram schematically showing an example of the configuration of the device according to the present invention. A diagram showing the illustration.

In the figure, 1 is a sample container, 2 is a sample stored in the container 1, and 3 is a main body of a pipette, on the lower end of which a nozzle tip 4 is replaceably attached. The pipette main body 3 is supported by a pulse motor-type pipette vertical drive mechanism 5 via a support rod (frame) 6, and applies negative pressure to the interior of the pipette for sucking liquid and for discharging liquid. It is connected via a tube 8 to a volume controller 7 which is connected to apply a positive pressure of . Reference numeral 9 denotes a drive control device for controlling the operation of the pipette vertical drive mechanism 5.

Reference numeral 10 denotes a spot-type reflective optical sensor fixedly supported by the support rod 6, such as an optical reflective sensor HEDS-1000.
(manufactured by Yokogawa Heuretsu Card Co., Ltd.) (see Figure 4). This spot-type reflective optical sensor 10 emits light source light toward the liquid surface by moving the lower end of the nozzle tip 4 of the pipette downward relative to the sample container 1, and detects light from the liquid surface incident on the light receiving section. It is designed to receive reflected light, and the level of the reflected light intensity reaches its maximum when the optical sensor 10 moves downward and approaches the focal length set in the convex lens (not shown) of the light receiving section. (See Figure 2). Therefore, when this maximum value is detected, the downward movement of the pipette is stopped (or the pipette may be moved further down a certain length from this point), and at this stop position, the nozzle tip 4 at the lower end of the pipette is kept in the liquid. What is necessary is just to provide it so that it is immersed only in depth. A known high peak detection circuit or the like can be used to detect each time the light intensity reaches the maximum value, and the gap distance l ₁ from the liquid surface where the maximum light intensity is obtained is determined by the slope of the liquid level. (curvature) is constant as shown in Figure 2 without being affected by liquid smudges, etc., and therefore the depth at which the pipette nozzle tip 4 is immersed in the liquid can be made constant with high precision. It is.

Figures 2 a and b show the relationship between the distance when the optical sensor approaches the liquid surface, the state of reflection of the light emitted from the optical sensor on the liquid surface, and the intensity of light incident on the optical sensor and detected. FIG.

Of these, FIG. 2a shows a case where the liquid level is maintained in a horizontal state, and FIG. 2b shows a case where the liquid level is inclined. Even if the liquid level in Figure 2b is inclined, the curve indicating the detection level of light intensity will be gentle, but the maximum value (peak) can still be detected, unless the slope is extremely extreme. I understand. The maximum value (peak) is taken as 100, and ±0.2 mm from the focal length that indicates this maximum value (peak).
It is preferable to use a highly sensitive type optical sensor such as an optical sensor in which the value of the detected light intensity decreases by about 10% due to the deviation of the sensor.

FIG. 3 shows a specific embodiment of the device of the present invention.

In this figure, numerals 1, 3, 4, 8, and 10 indicate the same devices and parts as schematically shown in FIG. 1 above. The pipette vertical drive mechanism 5 rotates a rotating shaft 5b by a pulse motor 5a, and rotates a cam 5c according to the amount of rotation of the pulse motor 5a, thereby moving the pedestal 11 supporting the pipette main body 3. Move it down. Therefore, the nozzle 4 attached to the lower end of the pipette 3 moves down by the amount of downward movement given above and enters the sample container.

The position where this nozzle 4 moves downward and stops is the first
As explained in the figure, the determination is made by the optical sensor 10 detecting the maximum value of the reflected light intensity.

The structure of the optical sensor of this example is as follows. This optical sensor 10 emits light from an LED light source 10a from a glass window 10c via a convex lens 10b having a focal point at 10e. The reflected light is made incident on the photodiode 10d via a convex lens 10b having the same focal length. The signal input/output of this optical sensor 10 is connected to the first
It is connected to the drive control mechanism 9 shown in the figure, and the maximum value of the intensity of light incident on the photodiode 10d is detected.

FIG. 5 shows a circuit for detecting the maximum value of light intensity in a block diagram, in which 15 is an oscillator;
6 is an amplifier, 17 is a detector, 18 is an A/D converter, and 19 is a microcomputer.
A so-called high peak detector constructed by these can be easily constructed using known electrical techniques. When the maximum value (high peak) of the light intensity is detected by the microcomputer 1, this information is transmitted to the pulse motor 5a, and the downward movement of the nozzle 4 is stopped.

FIG. 6 shows a flowchart for simply explaining the entire operating procedure of the apparatus of this example.

In this example, the pedestal 11 and the cam mechanism 5c are provided so that they can be operated in the horizontal direction by guide rods 13, 13. 12 is the overall support frame.

As a device having the above configuration, the diameter of the sample container 1 is
11mmφ, pipette internal volume 200μ, suction liquid volume 5μ
, Immersion depth of the lower end of nozzle tip 4 into the liquid is 3 mm.
and the focal length of the optical sensor 10 as
Experimentally, when the distance from the lower end of the optical sensor 10 to the lower end of the nozzle tip is 7.3 mm, the variation in the immersion depth of the nozzle tip 4 is 1 mm or less, and the variation in the amount of suction liquid is 2% or less. was confirmed.

Note that although the present embodiment shows that the nozzle and the sensor are fixed to the same control mechanism, they may be fixed to separate control mechanisms. In this case, the sensor first detects the liquid level, and based on the result, the nozzle is lowered.
All you have to do is keep it immersed in the liquid to a certain depth.

FIG. 7 shows an example in which such a nozzle and a sensor (optical sensor) are configured as separate mechanisms.

In the example shown in this figure, a vertical movement mechanism 2 that moves up and down an optical sensor stand 21 that supports an optical sensor 10 is shown.
2 is a predetermined initial position (maximum upward movement position)
While moving the optical sensor 10 downward, check the downward movement distance until the maximum value (high peak) of the light intensity is detected, and then rotate the pulse motor to a predetermined rotation based on the information on the detected downward movement distance. All you have to do is rotate it by the same amount. Specifically, after measuring a certain amount of sample, the result is stored in the memory of the control device, and when the sample is transferred directly below the nozzle, the measured value of the sample volume is retrieved from the memory and the nozzle is lowered. You will be asked to decide where to stop.

In the example shown in FIG. 7, the sample container 1 is supported by the sample rack 20.
This has no direct relation to the present invention.

FIG. 8 shows a flowchart for simply explaining the entire operating procedure of the apparatus in the example of FIG. 7.

(Effects of the Invention) According to the present invention, it is possible to quantitatively extract a minute amount of liquid with extremely high accuracy, and this invention greatly contributes to improving the precision of various qualitative and quantitative analyses. It also has the effect that it can be suitably used in various automatic analysis systems and devices, and its usefulness is extremely great.

[Brief explanation of the drawing]

FIGS. 1a and 1b are diagrams schematically showing an example of the configuration of a liquid quantitative extraction device according to the present invention, in which a shows the state of the pipette before it is immersed in the liquid, and FIG. 1b shows the state when the pipette is immersed in the liquid. Figure 2a shows the characteristics of the light intensity detected by the optical sensor used in the present invention.
Figures b and c are diagrams for explaining the relationship between the focal point position and the peak of light intensity. FIG. 3 is a perspective view showing a liquid quantitative extraction device according to the first embodiment of the present invention, FIG. 4a is a sectional view of an optical sensor, FIG. Figure 6 is a control block diagram of the pipette vertical drive mechanism, Figure 6 is a flowchart explaining the operation for taking out a fixed amount of liquid, Figure 7 is a diagram showing another embodiment of the device of the present invention, and Figure 8 is the operation for taking out a fixed amount of liquid. This is a flowchart explaining. 1: sample container, 2: sample, 3: pipette body,
4: Nozzle tip, 5: Pipette vertical drive mechanism,
5a: pulse motor, 5b: rotating shaft, 5c: cam mechanism, 6: support rod, 7: volume controller, 8: tube, 9: drive control device, 10: optical sensor (spot type reflective optical sensor), 10a :LED, 10b:
Lens, 10c: glass window, 10d: photodiode, 10e: focal point, 11: pedestal, 12: support frame, 13: guide rod, 14: electric cable, 15: oscillator, 16: amplifier, 17: detector, 18: A /D converter, 19: microcomputer, 20: sample rack, 21: optical sensor mount, 22: vertical movement mechanism.

Claims (1)

[Claims] 1 A pipette having a lower end nozzle for suctioning and discharging liquid, a pipette lowering control mechanism that moves the pipette downward to immerse the lower end nozzle in the liquid, and a pipette that moves downward and approaches the liquid surface while applying light to the liquid surface. A liquid quantitative dispensing device is provided with a sensor that projects light and detects reflected light from the liquid surface, and is configured to determine a downward movement stop point of a pipette based on information detected by the sensor, the sensor comprising: A spot-type reflective sensor having a light-converging optical element focused at a position a fixed length apart from the bottom is used, and the maximum light intensity point of the input reflected light is used as information for determining the point at which the pipette stops moving downward. Liquid quantitative extraction device.