JPH02184762A - Method for detecting blocking of automatic dispensing device - Google Patents

Abstract

PURPOSE:To speedily detect a clog by providing an air hose, a nozzle chip, and a sample tube and monitoring the pressure in the air hose. CONSTITUTION:While the liquid sample in the sample tube 16 is sucked and sampled, negative pressure is produced in the air hose 12 and drops gradually with time. Then when the intake of the nozzle chip 14 is closed owing to th suction of a solid body in the sample, the internal pressure in the air hose 12 does not returns to the atmospheric pressure and a sudden drop in the internal pressure occurs on the blocking occurrence. For the purpose, the internal pressure level of the air hose 12 which varies with suction time is sampled at a specific period while the liquid sample in the tubed 16 is sampled to detect the blocking state of the intake of the chip 14 speedily. Then the sucking operation is stopped at the same time the liquid sample which is sucked is discharged slightly immediately to separate a sucked material from the intake of the chip 14, thereby obtaining only the desired pure liquid sample.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for detecting blockage in an automatic dispensing device, and particularly to a method for detecting a blockage state caused by adsorption of a solid substance in a liquid sample to a nozzle tip.

[Prior art] Dispensing to collect a desired amount of sample by suction is essential in laboratory testing, etc., and generally there is a device that inserts a nozzle tip connected to a suction pump into the sample to collect a predetermined amount of sample by suction. Widely used.

Particularly in recent years, automatic dispensing devices that can perform each dispensing process continuously without human intervention have been developed, and are very suitable for processing many types of samples in a short time.

In normal cases, the sample to be dispensed is often a body fluid collected from a living body, such as serum or plasma, and the dispensed sample is mixed with reagents and other substances and subjected to a predetermined test.

[Problems to be Solved by the Invention] However, in reality, blood serum and plasma, which are generally subjected to automatic dispensing, are used in a state in which blood or the like has been centrifuged.

Since centrifugal agents and blood clots are mixed in the serum under such processing conditions, if the serum is directly put into the dispensing machine and subjected to dispensing, these substances will enter the extremely small nozzle tip inlet. The solid separation agent and blood clots are adsorbed and cause a blockage, making it difficult to continue the sample suction and collection operation.

In order to avoid these inconveniences, conventional methods require preliminary processing such as transferring the sample to a separate tube before applying it to the dispensing machine, which hinders the rapid progress of dispensing processing and is extremely The problem was that it was inconvenient.

Purpose of the Invention The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to prevent solid substances contained in a liquid sample from being adsorbed to the nozzle tip suction port during the suction action of the liquid sample. Easily and quickly detects the occurrence of blockages caused by the nozzle tip and removes adsorbed substances to ensure smooth and normal inhalation collection when non-analytes contain solid substances that may block the nozzle tip inlet. An object of the present invention is to provide a method for detecting occlusion in an automatic dispensing device that can realize the following.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an automatic system that absorbs and collects a predetermined amount of liquid sample by inserting a nozzle tip at the end of an air hose connected to a suction pump into a sample tube. In a method for detecting occlusion in a dispensing device, the air hose internal pressure level, which changes with the suction time during liquid sample collection in a sample tube, is sampled at a predetermined period, and the rate of change of the detected pressure level value with respect to the previously detected value is determined by a predetermined rate. The present invention is characterized in that when the above conditions are met, it is detected and determined that the suction port of the nozzle tip is in a closed state.

[Function] According to the method of the present invention configured as described above, the occurrence of so-called clogging, where the nozzle tip suction port for collecting a liquid sample is blocked by solid substances contained in the sample, can be prevented by connecting to the suction pump. It is possible to quickly detect pressure changes in the air hose as an indicator.

That is, while the liquid sample in the sample tube is being sucked and collected, the inside of the air hose becomes a negative pressure, and the internal pressure of the air hose gradually decreases as time passes.

If the suction operation is performed normally, the internal pressure of the air hose will return to atmospheric pressure when the sample collection is completed, but the suction port of the nozzle tip is blocked by solid matter such as fibrin in the sample. When this occurs, the air hose internal pressure does not return to atmospheric pressure as described above, and a sudden decrease in internal pressure occurs at the same time as this blockage occurs.

Therefore, by sampling the air hose internal pressure level, which changes with the suction time, at predetermined intervals during liquid sample collection in the sample tube, it is possible to quickly detect the blockage state of the nozzle tip suction port, which appears as a sudden drop in internal pressure. can do.

Then, at the same time as the blockage state is detected, the suction operation is stopped and the suctioned liquid sample is immediately discharged slightly, thereby making it possible to remove the adsorbed substance from the nozzle tip suction port.
Only the desired pure liquid sample can be taken.

[Example] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 schematically shows the principle configuration of an automatic dispensing device to which the method of the present invention is applied. A nozzle tip 14 is connected to the tip of an air hose 12 connected to the suction pump 10, and the nozzle tip 14 is inserted into a sample tube 16, such as a test tube, filled with a liquid sample in advance, and a predetermined amount is Collect a liquid sample by inhalation.

A characteristic feature of the present invention is that it prevents the occurrence of blockages caused by blood clots, which frequently occur when serum, plasma, etc. are used as liquid contaminants, and drugs added during centrifugation adsorb to the tip of the nozzle tip. The object of the present invention is to have a simple configuration that allows for accurate and quick detection, as well as immediate removal of the adsorbed substance from the nozzle tip to continue normal sample collection.

The reality is that in the past, there were almost no measures taken to prevent the nozzle tip inlet from becoming clogged during the sample suction and collection process. The reality is that the patient remains in a state of neglect until he or she consciously recognizes this, and is unable to continue normal inhalation work.

For this reason, when a liquid sample that can cause clogging is to be used, pretreatment such as filtering it is required, which can avoid inefficiency in dispensing work due to extremely troublesome labor and extended work time. There wasn't.

Under these circumstances, the method of the present invention focuses on the fact that large pressure fluctuations occur in the air hose at the same time as the nozzle tip suction port becomes clogged, and it is possible to reliably detect this and, by the time it becomes clear that a blockage has occurred, the suction has already been started. By returning a small amount of the liquid sample to the sample tube, the adsorbed substances are removed and normal suction collection is possible again.

A pressure sensor 18 is connected on the way to monitor the internal pressure of the air hose 12, and the output of the pressure sensor 18 is amplified by a DC amplifier 16, then supplied to a limiter 22, and converted into a digital signal by an A/D converter 24. converted.

The suction pump 10 to the limiter 22 constitute one channel, and by driving and controlling a plurality of channels usually arranged in parallel at the same time, it is possible to monitor the internal pressure of a large number of air hoses 12 at the same time. In this embodiment, only a single channel is shown for convenience of explanation.

The detection signal digitized within the A/D converter 24 is analyzed by the liquid sensing unit 26, and the result is sent to the host M.
When it is determined that the nozzle tip 14 is in a blocked state due to the action described below,
A nozzle/pump stop signal will be output to the suction pump 10 drive section.

The liquid sensing unit 26 outputs a signal specifying a channel to be monitored and controlled to the A/D converter 24 based on a command from the host MP028, and it is possible to monitor only a desired channel among a plurality of channels.

FIG. 2 is a graph showing the relationship between the internal pressure of the air hose 12 and the sample suction time when a blockage occurs in which a solid substance such as fibrin in a liquid sample is adsorbed to the suction port of the minute nozzle tip 14.

As described above, the method of the present invention maintains the suction action by catching the sudden drop in the internal pressure of the air hose 12 during suction.

If we consider this simply, if the internal pressure of the air hose 12 during suction drops to the conversion limit of the A/D converter 24, it can be unconditionally determined that a blockage has occurred.
This causes a problem in that the detection of the blockage state is delayed and the stuck substance is sucked deeply into the nozzle tip 14.

Therefore, when the pressure change becomes large to a certain extent, it is considered that a blockage state has occurred. However, if this is done alone, there is a risk that the pressure change at the start of the inhalation action may be erroneously determined as the occurrence of a blockage state, so the detection action is not performed at the start of the inhalation action.

In the graph of Fig. 2, the blockage check starts after a certain period of time after the start of the suction action, and the air hose
Monitor the pressure inside 2. Here, a blockage may occur immediately after the suction action of the liquid starts, so in order to deal with such a case, the check is started as soon as the air hose internal pressure drops to a certain level below the level at the start of suction.

That is, in the illustrated example, the occlusion check is entered at the same time as either 10 hours have elapsed since the start of the suction operation or the internal pressure of the air hose 12 has decreased by 90 degrees or more.

If the sample collection operation progresses normally without clogging the suction port, the pressure change curve shows that the internal pressure of the air hose 12 slowly decreases as shown by the chain line in the figure, and the specified sample suction is completed. Once completed, the internal pressure will quickly return to atmospheric pressure.

On the other hand, if a solid substance such as fibrin is adsorbed to the suction port at the tip of the nozzle tip during suction, causing a blockage, the suction operation by the suction pump 10 will continue even though the tip is blocked, so the air hose The internal pressure of No. 12 shows a sudden drop as shown in the figure.

Therefore, the slope of the graph at this time is 6 during the time Δt.
When the pressure changes by 1 or more, it is considered that a blockage condition has occurred. Then, at the same time as the blockage state is detected, the drive of the suction pump 10 is stopped, and a small amount of the liquid that has already been sucked into the nozzle tip 14 is returned to the non-sample tube 16, thereby removing the substance that had been adsorbed to the tip suction port. is washed away and returned to the sample tube 16, the adsorbed substances are removed, and the sample tube is placed in a state where normal sample suction can be performed again.

Note that 10 is set to the time at which the pressure change at the start of suction is stabilized, and p is set to t. It is sufficient to specify a level difference that is slightly higher than the current pressure.

Further, it must be noted that Δt becomes a substantially fixed value once the device is determined, and that if Δt is small, the detection response will be improved, but at the same time malfunctions will be more likely to occur.

[Effects of the Invention] As explained above, according to the method of the present invention, the internal pressure of the air hose to which the nozzle tip is connected can be monitored to detect the occurrence of so-called clogging in which the nozzle tip suction port is blocked by solid substances in the liquid sample. As soon as a blockage condition is detected, the suction operation is temporarily stopped, and a small amount of the liquid sample that has already been sucked is returned to wash away the adsorbed material and resume normal sample placement. For example, serum or plasma after centrifugation can be directly used for dispensing without any pretreatment, and even if a blockage occurs, it can be quickly removed. It becomes possible to continue the desired dispensing work.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of an automatic dispensing device to which the method of the present invention is applied, and FIG. 2 is a graph diagram showing the relationship between air hose internal pressure and suction time when a blockage occurs. 10... Suction pump 12... Air hose 14... Nozzle tip 16... Sample tube 18... Pressure test 20... DC amplifier 22... Limiter 24... A/D converter 26... ...Liquid sensing unit 28...Host MPU0

Claims (1)

[Claims] (1) In a blockage detection method for an automatic dispensing device in which a nozzle tip at the end of an air hose connected to a suction pump is inserted into a sample tube to absorb and collect a predetermined amount of liquid sample, when collecting a liquid sample in the sample tube. The air hose internal pressure level that changes with the suction time is sampled at a predetermined period, and if the rate of change of the detected pressure level value with respect to the previously detected value is more than a predetermined value, it is detected that the inlet of the nozzle tip is in a blocked state. A method for detecting occlusion in an automatic dispensing device, characterized by: