JP2013088300A - Method for inspecting air bubble and leakage by measuring pressure in fine tube - Google Patents

Abstract

The present invention provides a method for easily detecting the presence or absence of bubbles or leakage in a fine tube and a system therefor.
SOLUTION: A liquid is injected into a closed micropipe, the pressure in the micropipe is measured, and the time until the pressure starts to rise, the time until a constant pressure is reached, and the pressure rise rate are compared with the control. A method for inspecting the presence or absence of bubbles and the presence or absence of leakage in the fine tube. Presence / absence of bubbles in the micro-tube having a closed micro-tube, a pump connected to the micro-tube and pressurizing liquid into the micro-tube, a pressure sensor for measuring the pressure in the micro-tube, and an output device for the pressure measurement result And system for checking for leaks.
[Selection] Figure 3

Description

  The present invention relates to a method for inspecting whether there are bubbles or leaks in a fine tube for liquid feeding used in an inspection apparatus using a small amount of liquid sample, and a system used for the method.

  When measurement is performed by introducing a small amount of liquid into the inspection apparatus, if a bubble enters the microtube used for introducing the liquid or leakage occurs, the measurement result is adversely affected. For example, Patent Literature 1 discloses a blood test apparatus that evaluates thrombus formation and the like by flowing blood or a reagent into a microchip through a fine tube. In this method, as shown in FIG. 10, a liquid having a specific gravity smaller than that of blood, such as mineral oil, is filled in a microfeed pump, and this is press-fitted into a sample syringe containing the blood through a press-fitting tube (fine tube). Then, it is layered on the blood and the blood is pushed into the microchip and measured. However, if bubbles enter the press-fit pipe or a hole leaks in the press-fit pipe and the liquid leaks, there is a problem in that the measurement results vary and accurate measurement cannot be performed.

  In Patent Document 2, a pressure fluid is supplied to a tube or a container, a leakage flow rate in the tube or the container is measured while changing the pressure of the pressure fluid, and the degree of leakage of the tube or the container based on a change pattern of the leakage flow rate. A method of assessing is disclosed. However, this method relates to the evaluation of pipes or containers with large diameters such as underground pipes, and does not evaluate fine pipes connected to microchips, but measures the leakage flow rate while changing the pressure. It is.

Patent Document 3 discloses a method for confirming the presence of bubbles in a flow path with a microscope and image analysis. However, since this method requires a microscope and an image analysis apparatus, it is a large scale, and it is impossible to quantify bubbles.
Patent Document 4 discloses a method for determining the presence or absence of bubbles in a pipe in a dispensing device by measuring a pressure change in the pipe. This method captures pressure changes (number of peaks in the waveform of pressure changes) in a very short time, and uses a highly accurate device to calculate and judge. Can not.

International Publication No. 2007/46450 JP 59-052728 JP 2007-245038 A JP 2007-278834 A

  In inspection systems that use micro-channels, the amount of liquid delivered is so small that it is difficult to detect the presence of air bubbles in the channel that hinders measurement other than by visual inspection. It is difficult to detect bubbles before measurement. Therefore, it is desired to develop a method for easily detecting the mixing of bubbles into the micropipe. In addition, it is desired to develop a method for detecting leakage by a simple method.

In order to solve the above-mentioned problem, the present invention measures the pressure in a micropipe by injecting a liquid into a closed micropipe, the time until the pressure rise starts or reaches a certain pressure, and the pressure rise. A method for inspecting the presence or absence of air bubbles in the microtubule and the presence or absence of leakage is provided by comparing the speed of the airflow with the control.
The fine tube preferably has an inner diameter of 0.1 to 1 mm, and the liquid is preferably pressed into the fine tube at a flow rate of 1 to 10 μl / min.
The present invention also includes a micro tube having a closed system, a pump connected to the micro tube and press-fitting liquid into the micro tube, a pressure sensor for measuring the pressure in the micro tube, and an output device for the pressure measurement result. A system is provided for inspecting for the presence and absence of bubbles in a tube.
The present invention also provides the system further including an evaluation unit that determines the presence or absence of bubbles and the presence or absence of leakage from the measurement result of the pressure.
The present invention further provides a blood measuring device including the system.

According to the method of the present invention, the pressure in the microtube is measured by injecting a liquid into the closed microtubule, and the time until the pressure starts to rise or reaches a certain pressure and the speed of the pressure rise are compared with the control. By comparing, the presence / absence of air bubbles and the presence / absence of leakage in the fine tube can be easily and simultaneously inspected.
It is preferable that the fine tube has an inner diameter of 0.1 to 1 mm because the tube used for a minute amount measurement can be evaluated.
When the liquid is pressed into the microtube at a flow rate of 1 to 10 μl / min, it is preferable because it is easy to quantitatively evaluate the relationship between a small amount of leakage and bubbles and an increase in pressure. As the flow rate increases, the error in the change in pressure increases, so a minute amount of leakage or bubbles cannot be measured.
The present invention includes a closed micro tube, a pump connected to the micro tube and press-fitting liquid into the micro tube, a pressure sensor for measuring the pressure in the micro tube, and an output device for the pressure measurement result. According to the system for inspecting the presence or absence of bubbles and the presence or absence of leakage, it is possible to easily evaluate whether there are bubbles or leakage in the microtubule from the pressure pattern. It is preferable to further include an evaluation unit that determines the presence / absence of air bubbles and the presence / absence of leakage from the pressure measurement result, because it is possible to evaluate before using the microtube for actual measurement and to determine whether it can be used.
According to the blood measuring apparatus of the present invention, it is possible to check in advance whether air bubbles are contained in the fine tube of the blood observation apparatus. In many cases, bubbles in a microfluidic control device become an obstacle (an obstacle to pressure measurement and optical measurement) when analyzing, so it is important to verify before measurement.

The figure which shows the one aspect | mode of the apparatus used for the method of this invention. The figure which shows the one aspect | mode of the system of this invention. The graph which shows the relationship between the amount of bubble mixing and a pressure rise. The graph which shows the relationship between the amount of leakage, and a pressure rise.

  Hereinafter, the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and modifications and the like are allowed without departing from the gist of the present invention.

FIG. 1 shows an embodiment of an apparatus used in the method of the present invention.
A liquid feed pump 3 is connected to one end (starting end) of the micropipe 1 to feed a liquid such as water into the micropipe 1. The microtubule may have one or a plurality of branches such as branching from the branching portion 2 in FIG. In the method of the present invention, bubbles and leakage can be accurately detected even in a complicated system having a plurality of branches.

The ends of the microtubules are sealed at least at the time of measurement and constitute a closed system. For example, as shown in FIG. 1, the end of the tube branched from the branch portion 2 is sealed by a valve 6, and the end (end) of the microtube 1 can be sealed with a cap 5. . Note that the ends of the microtubules may always be blocked.

The flow rate is preferably a constant flow rate of 1 to 10 μl / min. More preferred is a constant flow rate of 3-7 μl / min. The liquid feed pump is not particularly limited as long as it can control the flow rate in the above range, and a commercially available micropump or the like can be used.
The liquid may be water, but may also be liquid paraffin, various oils and fats such as mineral oil and silicone oil, and physiological saline.
The material of the fine tube is not particularly limited. However, since it cannot be measured accurately when expanded due to internal pressure, a hard material is preferable, and examples thereof include plastics such as Teflon (registered trademark) and polypropylene, metals, and the like. The fine tube preferably has an inner diameter of 0.1 to 1 mm, and more preferably 0.2 to 0.7 mm. The length from the start end to the end of the fine tube is not particularly limited, but is preferably 0.3 to 0.7 m.

A pressure sensor 4 is attached to the microtube 1 to measure the pressure in the microtube.
When there are bubbles in the micro tube, the time to start the pressure rise and the time to reach a certain pressure will be slower than when there is no bubble, so measure the pressure rise pattern using the micro tube to be evaluated In addition, the presence or absence of bubbles can be evaluated by comparing with a reference pattern measured using a microtube that has been confirmed to be free of bubbles. Specifically, it can be determined that bubbles are present when the evaluation target is delayed in time until the start of pressure increase and / or time until reaching a certain pressure as compared with the control. It is also possible to change the amount of bubbles in advance to obtain the time to start pressure rise and / or the time to reach a certain pressure, measure the evaluation object, and quantify the amount of bubbles from the measured value. it can.

  On the other hand, when there is a hole in a part of the fine tube or when there is a leak due to a loose valve or connection part, the pressure rise rate is slower than when there is no leak. It is possible to evaluate the presence / absence of leakage by measuring the pressure increase pattern and comparing it with a reference pattern measured using a microtube that has been confirmed to have no leakage. Specifically, the evaluation object can be determined to have a leak when the pressure increase is delayed compared to the control. It is also possible to obtain the pressure increase rate in advance by changing the degree of leakage, measure the evaluation object, and quantify the degree of leakage from the measured value.

  In the method of the present invention, it is possible to investigate both bubbles and leaks by examining the time until the pressure starts to rise or the time until a certain pressure is reached and the rate of increase. That is, when the time until the pressure starts to rise or the time until the pressure reaches a certain pressure and the rate of increase decrease compared to the control, it can be determined that there are bubbles or leaks. It is possible to eliminate the factors that adversely affect the measurement results by removing air bubbles from the tube, plugging loose holes and holes that cause leakage, or replacing the micro tube, so accurate measurement can be performed. Can be avoided.

The system of the present invention includes a closed micro-tube, a pump connected to the micro-tube and press-fitting liquid into the micro-tube, a pressure sensor for measuring the pressure in the micro-tube, and an output device for the pressure measurement result, Furthermore, an evaluation unit that determines the presence / absence of bubbles and the presence / absence of leakage from pressure measurement results may be included.
As an output device, you can use graphs of pressure measurement values that are displayed on the screen or printed on paper, etc., and visually compare the graph with a reference pattern to check for bubbles or leaks. Can be determined.
An example of the system of the present invention will be described with reference to FIG. First, the pressure in the fine tube is detected by the pressure sensor (S101). Next, the detected value is compared with the value of the control measured in advance (S102). Based on the result, it is determined whether there is a leak or a bubble (S103). If there are no leaks or bubbles, an instruction is given to allow use (S104), and if there are leaks or bubbles, an instruction is given for leakage or removal of bubbles (S105). After removing the leak or air bubble, measure the pressure again to confirm that it has been removed. In addition, when there is a bubble or a leak, it may be instructed that it cannot be used.
The evaluation unit may be anything such as a computer connected to the pressure sensor, and based on the pressure increase pattern detected by the pressure sensor, this is compared with the control value input in advance, It can be determined that there is a leak.

The system of the present invention can be used for various measuring devices, but preferably, blood is flowed through a channel in a microchip disclosed in International Publication No. 2007/46450 to measure blood properties. Used for evaluation of microtubules used in blood observation devices. Specifically, it is a thrombus monitoring device for observing thrombus generation by flowing anticoagulated blood through a channel simulating a blood vessel in a microchip, and induces thrombus generation in at least a part of the thrombus It can be preferably used for a thrombus monitoring device having a thrombus generation chamber provided with a thrombus inducing material.
After confirming that there are no bubbles or leaks in the microtube using the system of the present invention, as shown in FIG. 10 of International Publication No. 2007/46450, the microtube is used as a press-fit pipe 317 and one end thereof is fed in a small amount. Connected to the liquid pump 330, the other end is connected to a reservoir (sample syringe 320) in which blood is stored, and the liquid feed pump 330 is filled with a liquid having a specific gravity smaller than that of blood, such as mineral oil. The sample syringe 320 is press-fitted from a (micro-tube), layered on the blood, press-fitted into the microchip 300 having the blood observation chamber 311, passed through the thrombus observation chamber 311, and the pressure change at that time is examined. The blood properties can be examined.
Accordingly, the present invention also provides a thrombus monitoring device incorporating the system.
The system of the present invention can also be used in a platelet evaluation apparatus as disclosed in WO 2010/018833.

Examples Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following modes.

Measurements were made with the system shown in FIG. The microtube 1 has an outer diameter of 1/16 inch (1.6 mm),
A Teflon (registered trademark) tube having an inner diameter of 0.02 inch (about 0.5 mm) was used. The microtube 1 was branched from the branch portion 2 and a valve 6 was provided at the end of the branched microtube to seal it. A pump 3 was connected to the starting end of the micropipe 1 and a liquid (mineral oil) was press-fitted into the micropipe using the pump 3. The end of the microtube 1 was sealed with a cap 5 to form a closed system. A pressure sensor 4 was provided in the middle of the microtube 1 to measure the pressure in the microtube.

After adding each amount (1, 2.5, 5 μl and a large amount) of bubbles into the microtube, mineral oil was injected at 5 μl / min, and the pressure pattern was measured. The results are shown in Table 1 and FIG. From FIG. 3, it was found that the time until the start of the pressure increase was delayed according to the amount of bubbles. Thus, it was found that the presence / absence of bubbles in the microtube can be measured by examining the time until the start of pressure increase. It was also found that the amount of bubbles can be measured by mixing a certain amount of bubbles in advance and examining the time until the pressure starts at that time. Furthermore, the presence or absence of bubbles can also be measured by examining the time required to reach a certain pressure.
In FIGS. 3 and 4, the pressure starts to increase after 20 seconds have elapsed, after 20 seconds from the state in which the mineral oil has been previously filled in the micropipe (the state where no liquid inflow pressure is applied). This is because pressure is applied.

Base ：圧力上昇(差分)を計算しているために、流していない時の圧力をBaseとして絶対
値‐Baseで圧力上昇を計算している。

Base: Since the pressure rise (difference) is calculated, the pressure rise is calculated as an absolute value -Base with the pressure when not flowing as Base.

  After the valve 6 was loosened so that each amount (T2> T3> T4> T5> T6) leaked into the fine tube, mineral oil was introduced at 5 μl / min, and the pressure pattern was measured. The results are shown in Table 2 and FIG. FIG. 4 shows that the pressure increase is delayed depending on the degree of leakage. Thus, it was found that the presence or absence of leakage in the micropipe can be measured by examining the rate of pressure increase. It was also found that the amount of leakage can be measured by making a certain amount of leakage in advance and examining the pressure increase rate at that time.

A: Pressure evaluation system, 1: Fine tube, 2: Branch, 3: Pump, 4: Pressure sensor, 5:
Cap, 6: Valve

  The method of the present invention can be usefully used for prior evaluation of a measurement system using a small amount of liquid.

Claims (7)

By measuring the pressure in the micropipe by injecting liquid into the closed micropipe and comparing the time to the start of the pressure rise or the time to reach a certain pressure with the control, the presence or absence of bubbles in the micropipe is determined. How to inspect. A method of inspecting the presence or absence of leakage in a micropipe by measuring the pressure in the micropipe by injecting liquid into a closed micropipe and comparing the rate of pressure increase with a control. The method according to claim 1, wherein the microtube has an inner diameter of 0.1 to 1 mm. The method according to claim 1, wherein the liquid is pressed into the microtubule at a flow rate of 1 to 10 μl / min. A closed micro-tube, a pump connected to the micro-tube and press-fitting liquid into the micro-tube, a pressure sensor for measuring the pressure in the micro-tube, and an output device for the pressure measurement results, A system for checking for the presence and absence of leaks. The system according to claim 5, further comprising an evaluation unit that determines the presence or absence of bubbles and the presence or absence of leakage from the measurement result of the pressure. A blood measurement apparatus comprising the system according to claim 5.

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