JP7371850B2 - Viscosity measuring device, surface tension measuring device, viscosity measuring method, and surface tension measuring method - Google Patents

Description

The present invention relates to a liquid sampling device capable of sampling even minute amounts of liquid. It also relates to microfluidic chips. The present invention also relates to a method for measuring the viscosity of a liquid. The present invention also relates to a method for measuring surface tension of a liquid.

Various experiments using biological samples or biosamples require operations such as moving and dispensing the samples. Depending on the type of experiment, the amount of sample required may be extremely small. With a typical pipette, the amount of sample collected (sampling amount) is excessive, resulting in inefficient sample movement relative to the required amount. However, commercially available micropipettes for collecting extremely small amounts of samples have sophisticated pump controls and are often expensive and difficult to use for general use. Further, when using a biological sample or a biological sample, it is preferable that the part that comes into direct contact with the sample is disposable.

Patent Document 1 discloses that a microflow pump is installed at the end of a path, a sample injector, a test tube, and a bubble detection section are installed at both ends of the test tube, and a carrier liquid is sent from the pump at a constant flow rate. Disclosed is a minute flow rate distributing method (claim 5) characterized in that bubbles are continuously injected at a desired constant interval while a certain amount of air is generated, and a constant amount between the bubbles is continuously taken out. WO 2005/000002 relates to a device for controlling bidirectional fluid flow and discloses a device having a pump operating in a continuous pump cycle having a pressurized phase and a depressurized phase.

There is also a demand for liquid feeding control using a small amount of liquid to be performed within a microfluidic chip. Patent Document 3 discloses that a capillary-like flow path is formed between two members bonded to each other, a decompression chamber is provided in communication with the path, and the decompression chamber is formed in a separate member from the member having the capillary-like flow path. Discloses a microchemical device that connects and fixes these members. Patent Document 4 discloses a liquid feeding system and the like that includes a pump that generates negative pressure, a flow cell, and a pipe that connects these.

There is also a need for viscosity measurement methods and surface tension measurement methods that use minute samples. For example, it is known that the viscosity of blood increases due to dehydration, hemorrhage, or various diseases such as myocardial infarction, cerebral infarction, liver cirrhosis, membranous nephropathy, and nephrotic syndrome. It has also been reported that when blood viscosity is high, the incidence of diabetes increases and kidney disease tends to become more severe.
Saliva secreted into the oral cavity from the salivary glands moistens the oral cavity to facilitate speech production and swallowing food, and also serves to keep the oral cavity clean and prevent tooth decay and periodontal disease. Furthermore, it has been pointed out that the saliva viscosity of patients suffering from periodontal disease is higher than that of healthy individuals, and that the higher the saliva viscosity, the more serious the periodontal disease.

Therefore, knowing the viscosity of body fluids such as blood and saliva and its changes over time is extremely important for the prevention, diagnosis, and treatment of various diseases. Conventionally, the viscosity of a liquid has been measured using a capillary viscometer (see Patent Document 5), a rotational viscometer (see Patent Document 6), a falling ball viscometer (see Patent Document 7), and an oscillatory viscometer (see Patent Document 8). ) etc. are used.

Japanese Patent Application Publication No. 2003-270018 Special Publication No. 2009-535557 Japanese Patent Application Publication No. 2001-88098 WO2015/119072 Japanese Patent Application Publication No. 2007-108045 Japanese Patent Application Publication No. 2015-175841 Japanese Patent Application Laid-Open No. 62-082340 JP2014-219338A

Various methods have been proposed for collecting a small amount of sample and for sending the liquid. However, these collection and liquid delivery methods use a pump or a reduced pressure phase as in Patent Documents 1 and 2, and require pulsation control of the pump and control of the degree of pressure reduction each time it is used. These included elements that were difficult to control or required advanced controls. In addition, in order to create a configuration that supports these controls, parts that include flow channels that come into direct contact with the sample may have complex designs, or the flow channels may be extremely large than the sample volume, making them difficult to replace. Met.

In addition, liquid delivery systems for use in microfluidic chips, etc., such as Patent Documents 3 and 4, have been disclosed, but these also require depressurization, etc., and the structure may be complicated. . Furthermore, it was difficult to control liquid feeding by controlling negative pressure (reduced pressure), and it was difficult to stop liquid feeding at an arbitrary position within the reactor. Further, even when a pump or the like is used, the pulsation of the pump may cause the liquid to be delivered to an area outside the set range within the flow path of the microfluidic chip.

Additionally, conventional viscometers are often unable to measure viscosity without a considerable amount of liquid, and there is a problem in how to stably measure viscosity when the amount of liquid to be measured is minute. there were.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid sampling device in which the sampling amount can be easily adjusted even for a minute amount of sample, and the parts that come into contact with the sample can be easily replaced. Another object of the present invention is to provide a microfluidic chip in which the flow of liquid in a channel can be easily controlled. Another object of the present invention is to provide a viscosity measuring method, a surface tension measuring method, etc., which can measure the viscosity and surface tension of even a small amount of sample.

As a result of extensive research in order to solve the above problems, the present inventors found that the following invention met the above objects, leading to the present invention. That is, the present invention relates to the following inventions.

<1> A main body portion having a capillary-like microchannel having a first opening and a second opening;
and a switching valve connected to the first opening side,
The switching valve has a flow path connected to the main body, and a flow path opened to the atmosphere and/or a flow path connected to a closed container.
<2> The liquid sampling device according to <1>, further comprising a hydrophobic tube connecting the main body and the switching valve.
<3> The liquid sampling device according to <1> or <2>, wherein the switching valve is a solenoid valve.
<4> The switching valve according to <1> to <3>, wherein the switching valve has a flow path connected to three or more flow paths and connected to the closed container that sends gas into the micro flow path. The liquid collection device according to any one of the above.
<5> The liquid sampling device according to any one of <1> to <4>, which includes a sensor that detects the position of the liquid contained in the microchannel.
<6> The sensor and the switching valve, which is a solenoid valve, are connected to a control unit, and a liquid suction amount can be set in the control unit, and the control unit is configured to open and set the switching valve for liquid suction. The liquid sampling device according to <5>, wherein the switching valve is closed when the sensor attached to the position of the microchannel corresponding to the liquid absorption amount detects liquid.
<7> The liquid sampling device according to <6>, wherein a plurality of the sensors are provided along the microchannel.
<8> Any one of <1> to <7>, comprising a storage part that accommodates a test liquid that is in contact with an opening at the second end of the microchannel, and a mounting table on which the main body part is placed. The liquid sampling device described in .

<9> A microfluidic chip, wherein the microchannel in the liquid collection device according to any one of <1> to <8> is a microchannel for processing a sample liquid to be collected.

<10> The microchannel has a storage section that accommodates the test liquid that is in contact with the opening at the second end of the microchannel, and a mounting table on which the main body section is placed;
The method according to <6> or <7>, further comprising a liquid suction time measuring means for measuring a passage time tx until the liquid passes a position detected by the sensor, with the time when the electromagnetic valve starts opening as a starting point t0. Fluid collection device.

<11> The test liquid was stored in the storage part of the liquid sampling device described in <10>, the tx was measured by the liquid absorption time measuring means, and the standard solution was measured based on the measured tx. A viscosity measuring method for measuring the viscosity of the test liquid by comparing the viscosity with the liquid absorption time txa.

<12> The liquid sampling device according to <8> contains a test liquid in the storage part, and the switching valve has a flow path connected to the closed container,
Position L0 of the liquid level of the test liquid in the microchannel when the switching valve is closed, and the test liquid in the microchannel when the switching valve is connected to the airtight container. Measure the liquid level position L1 of
A surface tension measuring method for measuring the surface tension of the test liquid by comparing the position L0 and the position L1 with positions at which a standard liquid is measured.
<13> The surface tension measuring method according to <12>, wherein the L0 and L1 are measured by a liquid level position measuring means that measures the position of the liquid level in the microchannel.

In the liquid sampling device of the present invention, the sampling amount can be easily adjusted even for a minute amount of sample, and the part that comes into contact with the sample can be easily replaced. Furthermore, the microfluidic chip of the present invention allows easy control of the flow of liquid in the channel. Further, the viscosity measuring method, surface tension measuring method, etc. of the present invention can measure the viscosity and surface tension even with a small amount of sample.

FIG. 1 is a schematic diagram for explaining a liquid sampling device according to a first embodiment of the present invention. FIG. 2 is a schematic diagram for explaining liquid collection by the liquid collection device according to the first embodiment. FIG. 3 is a diagram for explaining the amount of liquid sucked in by capillary action in the liquid sampling device of the present invention. FIG. 7 is a schematic diagram for explaining liquid collection and liquid feeding by a liquid collection device according to a second embodiment of the present invention. FIG. 7 is a schematic diagram for explaining liquid collection by a liquid collection device according to a third embodiment of the present invention. FIG. 7 is a schematic diagram for explaining a microfluidic chip using a liquid sampling device according to a fourth embodiment of the present invention. It is a graph which shows the result of measuring the liquid passage time in a microchannel using the liquid collection device based on the third embodiment of this invention.

The embodiments of the present invention will be described in detail below, but the explanation of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention will be described below unless the gist thereof is changed. is not limited to the content. Note that when the expression "~" is used in this specification, it is used as an expression including the numerical values before and after it.

[Liquid sampling device of the present invention]
The liquid collection device of the present invention includes a main body portion having a capillary-like microchannel having a first opening and a second opening, and a switching valve connected to the first opening side. , the switching valve has a flow path connected to the main body, and a flow path opened to the atmosphere and/or a flow path connected to a closed container.
In the liquid sampling device of the present invention, the sampling amount can be easily adjusted even for a minute amount of sample, and the part that comes into contact with the sample can be easily replaced.

The liquid sampling device of the present invention includes a main body portion having a capillary-like microchannel having a first opening and a second opening, and a switching valve connected to the first opening side. When a liquid is brought into contact with the second opening side of the microchannel, the main body part sucks the liquid that has been brought into contact with the microchannel due to capillary action. The amount of liquid sucked into this microchannel is determined by the condition in which the pressure in the space and the capillary force are balanced. This amount of liquid is suitable for sampling a small amount of liquid. In addition, since it is possible to suck in vertically upward against gravity, it is also suitable for collecting liquid from directly above or diagonally, as is commonly used as a liquid collecting device such as a pipette.

Further, a switching valve is connected to the first opening of the microchannel. This switching valve has a flow path open to the atmosphere and/or a flow path connected to a closed container. The pressure within the space of the microchannel can be adjusted by the channel open to the atmosphere or the channel connected to the closed container. When the switching valve is connected to a flow path open to the atmosphere or a flow path connected to a closed container with an atmospheric pressure equal to or lower than the same pressure (valve open state), capillary phenomenon occurs in the micro flow path. Liquid suction occurs. On the other hand, when the switching valve is closed, the pressure in the space up to the switching valve quickly balances with the capillary force, and suction stops.

In other words, when collecting a liquid into a microchannel, the second opening is brought into contact with the sample liquid to be sampled, and the switching valve is opened to allow the liquid to reach a predetermined space in the microchannel. Can absorb liquid. Further, when the switching valve is closed, capillary action immediately stops, and sampling of the test liquid can be stopped.

Further, in this liquid sampling device, a main body portion having a capillary-like microchannel having a first opening and a second opening comes into contact with the test liquid. This main body can be easily replaced because a capillary tube or the like can be used, and by replacing this main body, liquid can be collected using a new clean main body.

Moreover, by using the structure of such a liquid sampling device and making the shape of the microchannel into a microchannel for processing, a microfluidic chip can be formed. This process is appropriately selected depending on the type of microfluidic chip, and processes such as reaction, separation, and measurement of components accommodated in the microchannel are performed. In addition, the viscosity of a small amount of liquid can be determined by evaluating the fluidity of the test liquid in the microchannel, and the surface tension of a small amount of liquid can be determined by measuring the equilibrium position of the test liquid in the microchannel. I can do it.

[First embodiment]
FIG. 1 is a schematic diagram for explaining a liquid sampling device according to a first embodiment of the present invention. The liquid sampling device 101 includes a main body portion 11 and a switching valve 21 .

[Main body part 11]
The main body part 11 is a cylindrical body and has a capillary-like fine channel 110 in the center. The microchannel 110 has a first opening 111 at one end and a second opening 112 at the other end. The first opening 111 is connected to the flow path of the switching valve 21 via a pipe 211. The main body part 11 can use, for example, a capillary tube commercially available for chromatography sample spotting or electrophysiological experiment electrodes, a hydrophilic microchannel, etc., and the main body part 11 in the first embodiment is a capillary tube.

The main body portion 11 has a capillary-like microchannel 110, and the microchannel 110 has a thickness that allows capillarity to occur. The amount of liquid that enters the microchannel 110 is determined by the pressure within the microchannel space and the capillary force (surface tension) of the liquid. These factors include the inner diameter of the microchannel, the surface tension of the liquid, the connection state of the switching valve (capacity of the sealed container, the state of opening to the atmosphere, etc.), the affinity between the microchannel and the liquid, and the like. The inner diameter of a microchannel suitable for collection using such capillarity is about 1 mm or less.

In addition, the collection of a small amount of liquid is particularly suitable for use with small amounts of body fluids such as blood and saliva, which contain water as a main medium. For this reason, it is preferable that the main body portion 11 be made of a hydrophilic material to facilitate capillary action. The main body portion 11 may be made of glass, for example.

[Switching valve 21]
The switching valve 21 has a flow path connected to a pipe 211 and a flow path connected to a pipe 212 opened to the atmosphere, and connects these when in an open state and closes these flow paths when in a closed state. cut off. The switching valve 21 may be manually switched or may be a solenoid valve. Since the capillary phenomenon progresses relatively quickly, it is preferable to use an electromagnetic valve as the switching valve 21, which can instantly control the start and stop of liquid feeding using an electric signal, and which can easily adjust the amount of liquid to be collected. .

[Piping 211]
The first opening 111 of the main body 11 and the switching valve 21 can be connected by any means. Since the main body part 11 may be replaced each time it is used, it is preferable to connect it using a flexible tube or the like to facilitate this replacement. It is preferable to use a hydrophobic pipe for this pipe 211. As described above in part, it is preferable that the main body 11 be made of a hydrophilic material to facilitate capillary action. On the other hand, it is preferable that the liquid does not excessively enter beyond the first opening 111 of the microchannel 110 to the switching valve 21 side. By making the piping 211 a hydrophobic tube, capillarity is less likely to occur within the piping 211, and the liquid stops near the first opening 111.

FIG. 2 is a diagram for explaining an example of the work of collecting a liquid using the liquid sampling device 101. The second opening 112 of the liquid sampling device 101 is brought into contact with the liquid 51 contained in the container 41 (FIG. 2(a)). At the same time as the contact, a part of the liquid enters the microchannel 110. Further, when the switching valve 21 is opened and the space of the microchannel 110 is connected to the piping 212 via the switching valve 21, the capillary phenomenon continues, and the liquid 51 is in the microchannel 110. is sucked in, and the liquid level 511 gradually moves toward the first opening 111 (FIG. 2(b)).

After collecting the liquid up to a predetermined liquid level 512, the switching valve 21 is closed to shut off the microchannel 110 and the piping 212, and the second opening 112 is removed from the liquid 51 in the container 41. Liquid can be collected in the channel 110 up to the liquid level 512 (FIG. 2(c)). The liquid in this microchannel 110 can be sent out using hydrophilicity or surface tension by bringing the second opening 112 into contact with a highly hydrophilic or water-absorbing material, etc., and opening the switching valve. Gas can be sent in and out from the 212 side.

[Liquid 51]
As the liquid 51, any liquid in which capillarity occurs can be used. This liquid may be one in which various components are dissolved or dispersed. Samples of biological origin such as blood and saliva can also be used.

The amount of liquid collected by the liquid sampling device 101 can be set as appropriate depending on the purpose of use and various conditions that affect surface tension (thickness of fine piping), etc., but it may be within a range of 100 μL or less, 10 μL or less, 1 μL or less, or 100 nL or less. The lower limit can also be set to an extremely small amount of liquid, such as 10 pL or more, or 100 pL or more.

According to the liquid sampling device 101, liquid feeding can be quickly controlled. Further, the main body 11 and the piping 211 can be removed and safely disposed of if necessary, and liquid feeding control (liquid feeding, dispensing, sample movement, etc.) of a biological sample such as a trace amount of body fluid can be performed.

[Capillary force and pressure in space]
The liquid sampling device according to the present invention utilizes capillary phenomenon to collect liquid by utilizing the balance between capillary force and the force due to the pressure difference between the inside and outside of the capillary. FIG. 3 is a diagram for explaining this capillary force and the force due to the pressure difference between the inside and outside of the capillary, using a cylindrical capillary as an example.

Capillary force (Fs) is a force that draws liquid into a microchannel due to surface tension. This capillary force (Fs) can be determined from the following equation (A1).
Fs=2πrσ・cosα Formula (A1)
In equation (A1), π is pi, r is the radius of the capillary (m), σ is the surface tension (N/m), and α is the contact angle (rad).

The force (Fp) extruded from the tube is due to the difference in pressure between the inside and outside of the capillary. The force (Fp) extruded from this tube can be determined from the following equation (A2).
Fp=πr ² ΔP Formula (A2)
In formula (A2), π is pi, r is the radius (m) of the microchannel, and ΔP is the pressure difference (Pa) between the inside and outside of the microchannel.

Then, as shown in equation (A3), when these forces are balanced, the liquid level within the capillary becomes stationary.
Fs=Fp Formula (A3)

The condition for the balanced state of this equation (A3) is the state shown in the following equation (A4).
ΔP=4σ・cosα/D Formula (A4)
In formula (A4), σ is the surface tension (N/m), α is the contact angle (rad), and D is the inner diameter 2r (m) of the microchannel.

Using these equations, for example, when calculating water (with surface tension σ = 72 x 10 ^-3 N/m) using a capillary tube arranged horizontally with the switching valve closed, the total capacity is 0.25 ~ It is calculated that a minute amount of liquid, approximately 7 to 14 nL, can be collected into a 1 μL capillary tube with an inner diameter of 0.099 to 0.20 mm.

[Second embodiment]
FIG. 4 is a schematic diagram for explaining a liquid sampling device according to a second embodiment of the present invention and an example of its use. The liquid sampling device 102 includes a main body 12 , a switching valve 22 , and a closed container 32 . The liquid sampling device 102 will be described using an example in which the liquid 52 contained in the container 42 is sampled.

The main body 12 of the liquid collection device 102 has a capillary-like microchannel 120, and has a first opening 121 and a second opening 122. This main body section 12 can be the same as the main body section 11 of the first embodiment.

The switching valve 22 of the liquid sampling device 102 is a three-way valve. A first flow path of the switching valve 22 is connected to a first opening 121 of the main body 12 via a pipe 221. The piping 221 can be the same as the piping 211 of the first embodiment. The second flow path of the switching valve 22 is connected to the piping 222 and is open to the atmosphere. This piping 222 can be similar to the piping 212 of the first embodiment. The third flow path of the switching valve 22 is connected to the closed container 32 via piping 223. Further, the switching valve 22 can be configured to connect any two pipes from each of these pipes 221 to 223, or can be used as a shutoff valve to shut off these pipes.

[Airtight container 32]
The airtight container 32 is a container used to control the amount of suction due to the capillary phenomenon occurring within the capillary-like microchannel 120. As mentioned above, the amount of capillary action sucked in is determined by the balance between capillary force and the pressure within the space. As in the first embodiment, the pressure in this space may be released into the atmosphere by connecting the switching valve 22 to the piping 222 and sucked in by capillary action until it is balanced with gravity, etc. good. On the other hand, the amount of liquid sucked into the microchannel 120 can also be set by adjusting the pressure in the space in advance. For this purpose, the closed container 32 is connected to the microchannel 120 via the piping 223, and the amount of liquid corresponding to the capacity of the closed container 32 can be collected. This has the advantage that the amount of liquid sucked into the microchannel 120 can be easily adjusted by simply changing the volume of the closed container 32.

The liquid sampling device 102 controls the pressure inside the space using the closed container 32, but can be used in the same manner as the liquid sampling device 101 of the first embodiment in other respects.
For example, the switching valve 22 is used in a state where the pipe 221 and the pipe 223 connected to the closed container 32 are connected. When the second opening 122 of the microchannel 120 of the liquid collection device 102 is brought into contact with the liquid 52 contained in the container 42, the liquid 52 is sucked into the microchannel 120 by capillary action, and the liquid level 521 becomes the first. (FIG. 4(a)). Even if the switching valve 22 is maintained as it is, the liquid level 522 stops when it balances with the internal pressure of the closed container 32, and a predetermined amount of liquid is sucked into the microchannel 120 (FIG. 4(b)). . You can complete the liquid collection by removing the second opening 122 from the liquid 52 in this state, or you can pick up the liquid collection device 102 and move it with the switching valve 22 closed. A more stable state may be created within the flow path 120.

When supplying the liquid 52 to the container 421 as shown in FIG. The liquid droplet 523 can be moved into the container 421 by switching to a state where the piping 221 and the piping 222 are connected and sending gas from the piping 222 side toward the inside of the microchannel 120.

[Third embodiment]
FIG. 5 is a schematic diagram for explaining a liquid sampling device according to a third embodiment of the present invention and an example of its use. The liquid sampling device 103 includes a main body 13 , a switching valve 23 , and a closed container 33 . Further, the main body portion 13 is placed horizontally on a mounting table 73. The mounting table 73 has a groove serving as a liquid storage section 43, and a liquid 53 is stored therein. Sensors 631 to 636 capable of detecting the liquid level in the microchannel 130 of the main body section 13 are attached to the mounting table 73, and the sensors 631 to 636 are configured to communicate electrical signals to the control section 630. It is connected. The control unit 630 is also connected to the switching valve 23, which is a solenoid valve, so as to be able to communicate electrical signals.

The main body 13 of the liquid collection device 103 has a capillary-like microchannel 130, and has a first opening 131 and a second opening 132. This main body section 13 can be the same as the main body section 11 of the first embodiment.

The switching valve 23 of the liquid sampling device 103 is a three-way electromagnetic valve. A first flow path of the switching valve 23 is connected to a first opening 131 of the main body 13 via a pipe 231. The piping 231 can be the same as the piping 211 of the first embodiment. The second flow path of the switching valve 23 is connected to the piping 232 and is open to the atmosphere. This piping 232 can be similar to the piping 212 of the first embodiment. The third flow path of the switching valve is connected to the closed container 33 via piping 233. Further, the switching valve 23 can be configured to connect any two pipes from each of these pipes 231 to 233, or can be used as a shutoff valve to shut off these pipes.

[Placement stand 73]
The main body 13 of the liquid sampling device 103 is placed on a mounting table 73. The mounting table 73 has a structure in which a groove portion is provided for placing the main body portion 13 thereon. Further, the mounting table 73 also has a groove portion that serves as the liquid storage portion 43. A liquid 53 is contained in this storage portion 43 . When the main body portion 13 is placed on the mounting table 73, the second opening portion 132 is arranged to be in contact with the liquid 53 contained in the storage portion 43. The liquid sampling device 103 has a configuration in which the main body 13 is arranged horizontally when the mounting table 73 is placed on a horizontal table. The mounting table 73 may be replaced with a structure that allows the main body part 13 to be mounted not only horizontally but also at a predetermined angle, as appropriate.

[Sensors 631-636]
The sensors 631 to 636 are attached to a mounting table 73. A plurality of sensors 631 to 636 are provided in parallel in the microchannel 130 of the main body part 13 at predetermined intervals, and each sensor can detect a fluctuation in the microchannel 130 at a corresponding position. For example, the sensors 631 to 636 may be optical sensors that detect changes in the liquid level within the microchannel 130. When the liquid 53 is sucked into the microchannel 130, the liquid surface becomes significantly easier to observe by optical means due to the difference in refractive index and/or the difference in light scattering between the liquid and the gas in the space. Each of the sensors 631 to 636 can detect whether or not this liquid level has passed.

[Control unit 630]
The control unit 630 controls the opening/closing and connection state of the switching valve 23, which is a solenoid valve. The control unit 630 initially closes the switching valve 23 and places the main body 13 on the mounting table 73, and then connects the pipe 231 to the pipe 233 connected to the closed container 33 or the pipe 232 opened to the atmosphere. You can control the connection time. Further, it is connected to the sensors 631 to 636 so as to be able to communicate electrical signals, and it is possible to measure the time when the interface of the liquid 53 passes through a position corresponding to the sensors 631 to 636.

Further, the liquid absorption amount is set in advance in the control unit 630, and the control unit 630 opens the switching valve 23 for liquid absorption, and the control unit 630 opens the switching valve 23 for liquid absorption, and the control unit 630 opens the switching valve 23 for liquid absorption, and the microchannel 130 is attached to the position corresponding to the set liquid absorption amount. The switching valve 23 may be closed when the sensors (631 to 636) detect the liquid level. Thereby, the set amount of liquid can be absorbed into the microchannel 130. Communication between the control unit 630 and the switching valve 23 and/or the sensors 631 to 636 may be performed by any means such as wired or wireless. The liquid sampling device 103 also includes an input means for controlling the control unit 630 and a memory unit that stores information such as the control conditions of the control unit 630 and the liquid level passage time detected by the sensors 631 to 636 and its fluctuations. , it may have a display unit that displays this information as appropriate.

FIG. 5A shows a state in which the liquid 53 is contained in the storage portion 43 and the main body portion 13 is placed. When the control unit 630 opens the switching valve 23, which is an electromagnetic valve, to connect it to the closed container 33, for example, liquid is sucked into the microchannel 130. For example, when the liquid is sucked up to the liquid level 533, the sensor 633 detects the liquid level 533, and the detection result is transmitted to the control unit 630 (FIG. 5(b)). Further, when the liquid is sucked up to the liquid level 535, the sensor 635 detects the liquid level 535, and the detection result is transmitted to the control unit 630 (FIG. 5(c)).

Here, for example, if the amount up to the liquid level 533 is set as the sampling amount, when the sensor 633 detects the liquid level 533, the control unit 630 immediately controls the switching valve 23 in response to the detection result of the sensor 633. The switching valve 23 is closed by transmitting an electric signal to close the switching valve 23. Thereby, the amount up to the liquid level 533 can be collected.

Note that another sealed container (not shown) is attached to the piping 232 , and this sealed container has a positive pressure or a flexible container, and by connecting it to the piping 222, the sealed container can be closed. The liquid 53 sucked into the microchannel 130 is pumped out by positive pressure, or the gas is pumped into the microchannel 130 by pushing a flexible container. The liquid 53 may be sent out.

The liquid sampling device 103 of this embodiment takes the time when the switching valve 23, which is a solenoid valve, starts to open as a starting point t0, and measures the passage time tx1 to tx6 until the liquid passes the position detected by the sensors 631 to 636. The liquid absorption time measuring means may be provided. The time when passing the sensor 631 is tx1, the sensor 632 is the time tx2, the sensor 633 is the time tx3, the sensor 634 is the time tx4, the sensor 635 is the time tx5, and the sensor 636 is the time tx6. Measure. The liquid absorption speed can also be determined from the distance between each sensor and the passage time.
Further, in this liquid sampling device 103, when the switching valve 23 is in a closed state, the surface tension is balanced with very little liquid being absorbed, and the position of the liquid level is determined. Moreover, when the switching valve 23 is opened, liquid suction starts. Therefore, it is easy to control the timing of measuring the passing time. For example, by arranging a plurality of liquid sampling devices 103 in parallel, the passage times of a plurality of test liquids can be evaluated simultaneously.

Further, the sensors 631 to 636 may include more sensors, or may each detect the position of the liquid level over a wider range. As a device for measuring such positions, the liquid level position L0 with the switching valve 23 closed is measured, and the liquid level position L1 is further measured when the switching valve 23 is connected to the closed container 33. It can also be used as surface position measuring means.

[Fourth embodiment]
FIG. 6 is a schematic diagram for explaining a microfluidic chip using a liquid sampling device according to a fourth embodiment of the present invention. The microfluidic chip 104 includes a main body 14 , a switching valve 24 , and a closed container 34 . Furthermore, the main body portion 14 can be placed horizontally by placing its bottom surface on a table or the like. Sensors 641 and 642 capable of detecting the liquid level in the microchannels 1401 and 1402 are attached to the main body part 14, and the sensors 641 and 642 are connected to the control part 640 so as to be able to communicate electrical signals. There is. The control unit 640 is also connected to the switching valve 24, which is a solenoid valve, so as to be able to communicate electrical signals.

[Microchannels 1401, 1402]
The main body 14 of the microfluidic chip 104 has capillary microchannels 1401 and 1402, and has a first opening 141 and a second opening 142. The fine flow channels 1401 and 1402 are inner diameter flow channels in which capillarity occurs. Further, the microchannels 1401 and 1402 are microchannels for reacting the sample liquid to be collected. The main body part 14 has a liquid storage part 143 in a part that contacts the second opening 142, and the liquid stored in the storage part 143 is sucked in from the second opening 142 by capillary action and becomes a fine stream. The liquid is sucked into the first opening 141 through the channel 1401 and the fine channel 1402. A predetermined reaction is performed in these microchannels 1401 and 1402.

The fine channel 1401 is a fine channel from the second opening 142 to the position where the sensor 641 is provided. The fine flow path 1402 is a flow path continuous with the fine flow path 1401, and is a flow path from the position where the sensor 641 is provided to the first opening 141. In the fine channel 1402, a reagent 8 is arranged in an elliptical channel immediately after the sensor 641, and the sucked liquid is mixed and stirred with the reagent 8 and sucked toward the first opening 141. .

Depending on the purpose of using the microfluidic chip 104, this microchannel can be a channel that is an appropriate combination of any shape, such as a straight line, a branch, a comb shape, a curved line, a vortex, a bend, or an ellipse. Furthermore, any reagent or the like may be appropriately placed in the channel, or other openings may be provided to allow a plurality of liquids to pass through.

The switching valve 24 of the microfluidic chip 104 is a three-way electromagnetic valve. A first flow path of the switching valve 24 is connected to a first opening 141 of the main body 14 via a pipe 241. The piping 241 may be the same as the piping 241 of the first embodiment, and the first opening 141 of the main body 14 for connection to the piping 241 is a convex portion. The second flow path of the switching valve 24 is connected to the piping 242 and is open to the atmosphere. This piping 242 can be similar to the piping 212 of the first embodiment. The third flow path of the switching valve 24 is connected to the closed container 34 via piping 243. Further, the switching valve 24 can be configured to connect any two pipes from each of these pipes 241 to 243, or can be used as a shutoff valve to shut off these pipes.

Sensors 641 and 642 are attached to the main body part 14. These can be used to control reaction time within the microfluidic chip 104, etc. For example, the time from when the liquid sucked from the second opening 142 through the microchannel 1401 passes through the sensor 641 to when it reaches the sensor 642 while being mixed with the reagent 8 and being stirred is measured. Further, as soon as the sensor 642 confirms that the liquid level has passed, the switching valve 24 is closed to stop the liquid from flowing. After a predetermined reaction time has elapsed in this stopped state, the switching valve 24 is opened to allow the liquid to proceed. Since the microfluidic chip 104 according to the present invention performs liquid delivery by capillary phenomenon, there is no effect of pulsation when using a pump, etc., and by appropriately arranging and controlling sensors, it can be moved to any position with high responsiveness. It is possible to send liquid up to This makes it possible to achieve a microfluidic chip that performs advanced liquid feeding control.

[Measurement of viscosity]
The viscosity measurement method of the present invention uses the liquid sampling device of the present invention to store a test liquid in a storage part, measure tx with a liquid absorption time measuring means, and prepare a standard solution based on the measured tx. The viscosity of the test liquid can be measured by comparing it with the measured liquid absorption time txa.
By using such a viscosity measuring method, it is possible to measure the viscosity of even a small amount of the test liquid. Based on this liquid absorption time tx, the time required for the test liquid to pass a predetermined distance can be determined. For example, when using a liquid sampling device with multiple sensors, the time tx1 is the time when the sample liquid sucked after opening the solenoid valve passes the first sensor that detects the liquid level position Lp1. , a case where the time when the liquid passes the second sensor that detects the liquid level position Lp2, which is closer to the electromagnetic valve than the position Lp1, is tx2 will be explained as an example. In this case, the test liquid is absorbed and passes through the distance Lp21 (=Lp2-Lp1) between the first sensor position Lp1 and the second sensor position Lp2 at time tx21 (=tx2-tx1). . If this is similarly measured using a standard solution, let txa1 and txa2 be the times, then by comparing with the time txa21 (=txa2-txa1) when using this standard solution, you can determine the relative value of the test solution to the standard solution, etc. Viscosity can be measured. Furthermore, by sufficiently evaluating the conditions of the standard solution, it is also possible to measure the absolute viscosity of the test solution.

This viscosity measurement is performed by regression analysis based on the flow path through which the body fluid flows due to the action of force due to capillarity, the distance traveled by the body fluid along the flow path, and the travel time required to travel the distance. However, the measurement can be carried out by a measuring device including a calculating means for deriving the viscosity of the body fluid. Preferably, this calculation means performs a regression analysis using the square of the travel distance as an explanatory variable and the travel time as a target variable.

How to measure the viscosity of a test liquid by regression analysis will be explained below. Consider a situation in which a liquid flows in a horizontally arranged pipe with a circular cross section (radius r) under the following conditions.
An attractive force F _s due to surface tension acts on the liquid in the tube toward one end that is in contact with the test liquid storage portion and the other end.
The volume of the accommodating part is larger than the volume inside the tube, and one end of the tube is immersed in the liquid in the accommodating part until the liquid that has entered the tube from one end of the tube reaches the other end.

Here, the surface tension of the liquid is σ, the contact angle of the liquid with the inner wall of the tube is α, the length of the liquid column consisting of the liquid in the tube is l, the viscosity of the liquid is η, and the speed at which the liquid moves inside the tube is v. , the attractive force F _s and the frictional force F _f acting on the liquid column in the pipe are expressed by the following equations 1 and 2, respectively.

When the density of the liquid is ρ and the equation of motion of the liquid moving in the pipe is expressed by taking into account the attractive force F _s and the frictional force F _f , the equation of motion becomes as shown in the following equation 3.

By rearranging Equation 3 with lv=q, the following Equation 4 can be obtained.

When the liquid moving in the pipe is in a steady state, that is, the state where Equation 5 below holds true, q can be expressed by Equation 6 below.

If Equation 6 is integrated under the condition of l=0 at time zero, the following Equation 7 can be obtained. Note that t means the elapsed time from time zero.

Equation 7 is the Lucas-Washburn equation under the condition that the tube is arranged horizontally and the driving force acting on the liquid as it moves along the tube is surface tension.

Equation 7 can be simply expressed as Equation 9 below by using A shown in Equation 8 below.

Note that in Equation 9, D (=2r) is the inner diameter of the tube. From Equation 9, it can be seen that the moving time of the liquid in the pipe is proportional to the square of the moving distance, and the proportionality coefficient is proportional to the viscosity of the liquid.
Here, if the type of liquid whose viscosity is to be measured is determined (for example, human saliva), individual differences in surface tension and contact angle between liquids are negligible compared to individual differences in viscosity between liquids. There are cases where In the case of conditions where these can be ignored, in the xy coordinate system where x = l ² and y = t, the slope of the straight line represented by y = bx + a, that is, the value of slope b (hereinafter also simply referred to as "slope b"). It can be seen that there is a proportional relationship between the viscosity of the liquid and the viscosity of the liquid, as shown in FIG.

Therefore, for example, if the slope b can be determined, based on a relationship between the viscosity of a standard liquid whose viscosity is known and the slope b, the absolute value of the viscosity of the liquid (for example, , the unit is mPas) can be derived. That is, in comparison with the viscosity based on the absorption time txa when measuring the standard solution, tx of the test liquid is also measured by the absorption time measuring means, and the viscosity is measured based on the measured tx. I can do it.
Furthermore, since there is a one-to-one relationship between the slope b and the viscosity of the liquid, the slope b may be treated as a relative value of the viscosity of the liquid. As an example of using the slope b as a relative value of the viscosity of a liquid, by calculating the slope b of a specific body fluid of a person at different times and examining the change in slope b, the viscosity of the body fluid of that person can be determined. (For example, the viscosity of saliva became 1.3 times more viscous after breakfast compared to before breakfast.)

Then, perform a regression analysis based on the distance traveled by the liquid along the pipe and the travel time required to travel that distance (for example, the square of the distance traveled by the liquid is used as the explanatory variable, and the travel time is used as the target variable). By doing so, b of y=bx+a can be derived.

・When there is a pressure difference between both ends of the pipe Up to this point, the explanation has been based on the assumption that the pressure acting on the liquid at both ends of the pipe is equal, but if we consider the case where there is a pressure difference between both ends of the pipe, When the pressure difference is ΔP' (for example, when one end of the pipe is at atmospheric pressure and the other end of the pipe is at negative pressure), where A ₁ is the value expressed by the following equation 10, equation 9 is expressed as the following equation: It becomes 11.

In Equation 11, if the pressure difference ΔP' between both ends of the pipe remains unchanged, the viscosity of the liquid is determined from Equation 11 through regression analysis using the same idea as deriving the viscosity of the liquid from Equation 9 through regression analysis. It turns out that it is possible.

・When the pipe is arranged vertically Also, if we consider the case where the pipe is arranged vertically and the lower end (one end) of the pipe is immersed in the liquid in the container, the liquid column inside the pipe will be affected by gravity in addition to surface tension. Therefore, the first item on the right side of Equation 3 becomes Equation 12 below.

However, upward direction is considered positive.

・When placing a pipe tilted from the vertical direction If the pipe is tilted at an angle θ from the vertical direction, g (gravity) in Equation 12 can be replaced with g cos θ, so the equation of motion of the liquid moving inside the pipe is as follows. It can be expressed by Equation 13.

When the liquid moving obliquely upward in the tube reaches a steady state, the left side of Equation 13, that is, the inertia term disappears, so the equation of motion in the steady state becomes Equation 14 below, and rearranging Equation 14 gives Equation 15.

When the liquid moves in the pipe and the length of the liquid column in the pipe reaches the length l _c shown in Equation 16 below, the upward force due to surface tension and the downward force due to gravity are balanced, and the liquid column becomes The length will not change.

When formula 15 is rearranged using l _c , the following formula 17 is obtained.

By solving Equation 17 for time t, the following Equation 18 can be obtained.

However, in Equation 18, F(l _c , l) and B are expressed by Equations 19 and 20 below, respectively.

Equation 18 is more complicated than Equation 7 when the tube is placed horizontally, but since the functions F(l _c , l) and B do not include the viscosity η, the time t for the liquid to rise along the tube It can be clearly seen that is proportional to the liquid viscosity η.
Expression 18 is expanded under the condition of l<<l _c to derive an approximate expression. First, by setting x=l/l _c and leaving out the logarithmic term x ² , it can be approximated as shown in Equation 21.

Substituting Equation 21 into Equation 18 results in Equation 22 below, and Equation 18 reduces to Equation 9.

Therefore, under the condition l<<l _c , even if the pipe is not horizontal, the moving time of the liquid in the pipe is proportional to the square of the moving distance, and the proportionality coefficient is proportional to the viscosity. Therefore, it can be seen that even if the pipe is arranged vertically or obliquely to the horizontal, the viscosity of the liquid can be derived by regression analysis.

In addition, when the pipe is arranged diagonally to the vertical or horizontal, and there is a pressure difference ΔP' between both ends of the pipe (for example, when one end of the pipe is at atmospheric pressure and the other end is under negative pressure) ) is Equation 14,
2πrσ·cos α may be replaced with 2πrσ·cos α+πr ² ΔP′. At this time, l _c is expressed by the following equation 23.

In this way, the following equation 24, which is similar to equation 18, can be obtained.

Also in Equation 24, the following simplified equation (Equation 25) holds true under the condition l<<l _c .

Equation 25 is the same equation as Equation 10, and in Equation 25, A ₁ is expressed by the following Equation 26 as in Equation 10.

Therefore, it can be seen that even if the pipe is arranged vertically or obliquely to the horizontal and there is a pressure difference ΔP' between both ends of the pipe, the viscosity of the liquid can be derived by regression analysis.

[Measurement of surface tension]

The surface tension measurement method of the present invention uses the liquid sampling device of the present invention, in which a test liquid is stored in a storage part, a switching valve has a flow path connected to a closed container, and the switching valve is closed. Measure the position L0 of the liquid level of the test liquid in the microchannel in the state and the position L1 of the liquid level of the test liquid in the microchannel when the switching valve is connected to the airtight container. By comparing L0 and position L1 with the position when measuring the standard solution, the surface tension of the test liquid can be measured.
By using such a surface tension measurement method, it is possible to measure the surface tension of even a small amount of the test liquid. For the liquid level position L0 and the liquid level position L1, values obtained by reading scales arranged in accordance with the flow path of the capillary tube may be used. Alternatively, the position of the liquid level may be detected by a sensor and the detected position may be used.

Surface tension can be calculated from the following concept. When the surface tension acting on the sample in the capillary tube and the force due to the pressure inside the capillary tube are balanced, the sample stops moving. The force balance condition is ΔP=4σcosα/D. From the equation of state (under constant temperature), ΔV/V+ΔP/P=0. From these, the following equation (a1) is obtained.

Here, P (atmospheric pressure), D (capillary inner diameter), and V (total volume) are constant. Further, since the intrusion (suction) volume ΔV is the capillary cross-sectional area multiplied by the intrusion distance ΔL, the intrusion volume ΔV is proportional to the penetration distance ΔL. Therefore, by measuring ΔL, the surface tension σ can be determined. This ΔL is determined from the position L1−position L0.

By measuring ΔL of a standard sample (eg, pure water) and measuring ΔL of a test sample (eg, saliva), it is possible to relatively evaluate the surface tension value of the sample.

Further, the distance ΔL is proportional to the total volume V. Therefore, by sequentially changing the total volume V, recording ΔL, and performing regression analysis, the value of surface tension can be determined more precisely. This total volume V can be adjusted, for example, by changing the volume of the closed container 33 in the third embodiment. In addition, by providing a plurality of switching valves 23 and making it possible to select a plurality of closed containers to be connected, it is possible to calculate the You can also ask for

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is changed.

[Viscosity measurement example]
The viscosity was measured from the flow rate of the liquid using a liquid sampling device (see the third embodiment) in which the main body was placed on a mounting table equipped with an optical sensor.

Connect a drip extension tube (nominal 0.7 mL) to a horizontally installed capillary tube (length 100 mm, inner diameter 0.68 mm) via a silicone tube (inner diameter 1 mm) and a syringe needle (18G: outer diameter 1.2 mm). A solenoid valve was installed at the end. The other end of the solenoid valve was opened to the atmosphere, and the solenoid valve was initially closed.
With this electromagnetic valve closed, when a sufficient amount of sample (pure water or saliva) was brought into contact with the open end of a capillary tube placed horizontally on a mounting table, it penetrated approximately 10 mm into the capillary tube and came to rest. When the electromagnetic valve is opened in this state, flow starts within the capillary tube, and the viscosity can be measured by measuring the time during which the liquid passes through a predetermined position.

FIG. 7 shows a measurement example in which "pure water" and "saliva" were measured as measurement samples. FIG. 7 shows the measurement of the passage time of the liquid surface using five sensors arranged at equal intervals. Saliva has a higher viscosity than pure water, and the time taken to pass the liquid through the sensor at each point was slower. The ratio of the viscosity values of pure water and saliva can be determined by appropriately performing regression analysis or the like and comparing the liquid passage times of the detection peaks of the sensors arranged at these five points.

Furthermore, by using a plurality of electromagnetic valves, a plurality of samples can be held stationary in independent capillary tubes. By simultaneously opening these multiple electromagnetic valves, the liquid flow rate can be monitored and the viscosity of multiple samples can be measured and compared at the same time.

[Surface tension measurement example]

Surface tension was measured from changes in the liquid level using a liquid sampling device (see the third embodiment) configured to place the main body on a mounting table. Connect a drip extension tube (nominal 0.7 mL) to a horizontally installed capillary tube (length 100 mm, inner diameter 0.68 mm) via a silicone tube (inner diameter 1 mm) and a syringe needle (18G: outer diameter 1.2 mm). A solenoid valve was installed at the end. A tube (capacity: 4 mL; end closed) was connected to the other end of the solenoid valve. At the start of measurement, this solenoid valve is closed.

When a sufficient amount of sample (pure water or saliva) is brought into contact with the open end of a capillary tube placed horizontally on a mounting table with this solenoid valve closed, it penetrates approximately 10 mm into the capillary tube and comes to rest (L0 ). Here, L0 is the position of equilibrium when the volume from the open end of the capillary tube to the inlet of the electromagnetic valve is V in equation (a1). When the electromagnetic valve is opened in this state, flow starts within the capillary tube, and the capillary force and the pressure within the capillary tube are balanced at the position of the new penetration distance L1. Surface tension can be determined by measuring the difference ΔL between L0 and L1.

ΔL (=L1−L0) is proportional to σcosα. The surface tension σ of pure water is 72×10 ⁻³ N/m, and the contact angle with respect to a clean glass surface is almost zero. From this, σcosα of the sample (saliva) can be determined using pure water as a reference.

The ΔL of pure water was 63.6 mm as the average of three measurements. On the other hand, the ΔL of saliva was 51.75 mm as the average of three measurements. From this result, the surface tension of the saliva used in this test was determined from the calculation of "ΔL (saliva) / ΔL (pure water) x surface tension of pure water", and was approximately 58.6 × 10 ^-3 N/m. Met. Note that, as described above, regression analysis can also be performed by changing the volume V of the closed container (tube) connected to the solenoid valve stepwise and measuring ΔL for each step.

Unlike the conventional capillary method (capillary rise method), this surface tension measurement method does not require information on sample density (mass per unit volume) to calculate the surface tension value, and can be measured with a minute amount of sample. be. After measurement, the test liquid storage section, mounting table, and capillary tube can be safely disposed of as one unit, making it suitable for measuring biological samples. Furthermore, it is easy to obtain multiple measurements necessary for regression analysis. Therefore, highly reliable measurements can be performed with simple operations.

INDUSTRIAL APPLICATION This invention can be utilized for collection of a trace amount of liquid, a microfluidic chip, viscosity measurement, and surface tension measurement of a liquid, and is industrially useful.

101, 102, 103 Liquid collection device 104 Microfluid chip 11, 12, 13, 14 Main body 110, 120, 130, 1401, 1402 Microchannel 111, 121, 131, 141 First opening 112, 122, 132 , 142 Second opening 143, 43 Storage part 21, 22, 23, 24 Switching valve 211, 212, 221, 222, 223, 231, 232, 233, 241, 242, 243 Piping 32, 33, 34 Sealed container 41, 42, 421 Container 51, 52, 53 Liquid 511, 512, 521, 522, 533, 535 Liquid level 630, 640 Control section 631-636, 641-642 Sensor 73 Mounting table 8 Reagent

Claims (7)

a main body having a capillary-like microchannel having a first opening and a second opening;
a switching valve connected to the first opening side and having a flow path connected to the main body portion and a flow path connected to a flow path open to the atmosphere ;
a sensor that detects the position of the liquid contained in the microchannel;
a storage part that contains a test liquid that is in contact with an opening at a second end of the microchannel and is open to the atmosphere; a mounting table on which the main body part is placed;
a control unit comprising a liquid absorption time measuring means for measuring the travel time for the test liquid to move through a predetermined position in the capillary microchannel, and a calculation means for deriving the viscosity of the test liquid;
A viscosity measuring device with A test liquid is stored in the storage part of the viscosity measuring device according to claim 1,
A regression analysis is performed based on the travel distance and travel time required for the movement of the test liquid at a predetermined position in the capillary-like microchannel by the action of force due to surface tension of capillary phenomenon, and A viscosity measuring method characterized in that the viscosity is derived by the calculation means. 3. The viscosity measuring method according to claim 2, wherein the calculation means performs regression analysis using the square of the travel distance as an explanatory variable and the travel time as a target variable. In the viscosity measuring method according to claim 2 or 3,
Bringing an opening at the end of the second opening into contact with the test liquid while the switching valve is closed;
In a state where the test liquid flows into the capillary-like microchannel and is stopped by the action of force due to surface tension of capillary phenomenon,
Switching the switching valve to connect it to a flow path open to the atmosphere,
The time when the switching valve is switched and connected to the flow path open to the atmosphere is the time measurement start point,
Measuring the passage time until the test liquid passes a position detected by a sensor installed at a predetermined position with the liquid absorption time measuring means,
A viscosity measuring method characterized in that the viscosity of the test liquid is derived by the calculation means. a main body having a capillary-like microchannel having a first opening and a second opening;
and a switching valve connected to the first opening side,
The switching valve has a flow path connected to the main body, a flow path open to the atmosphere, and/or a flow path connected to the main body.
has a flow path connected to a closed container,
The sample is placed in the storage part of the liquid sampling device, which has a storage part that stores the test liquid that is in contact with the opening at the second end of the microchannel, and a mounting table on which the main body part is placed. containing a liquid and having a flow path connecting the switching valve to the sealed container,
Position L0 of the liquid level of the test liquid in the microchannel when the switching valve is closed, and the test liquid in the microchannel when the switching valve is connected to the airtight container. Measure the liquid level position L1 of
A surface tension measuring method for measuring the surface tension of the test liquid by comparing the position L0 and the position L1 with positions at which a standard liquid is measured. 6. The surface tension measuring method according to claim 5 , wherein the L0 and L1 are measured by a liquid level position measuring means that measures the position of the liquid level in the microchannel. a main body having a capillary-like microchannel having a first opening and a second opening;
and a switching valve connected to the first opening side,
The switching valve has a flow path connected to the main body, a flow path open to the atmosphere, and/or a flow path connected to the main body.
has a flow path connected to a closed container,
The sample is placed in the storage part of the liquid sampling device, which has a storage part that stores the test liquid that is in contact with the opening at the second end of the microchannel, and a mounting table on which the main body part is placed. containing a liquid and having a flow path connecting the switching valve to the sealed container,
Position L0 of the liquid level of the test liquid in the microchannel when the switching valve is closed, and the test liquid in the microchannel when the switching valve is connected to the airtight container. Measure the liquid level position L1 of
A surface tension measuring device that measures the surface tension of the test liquid by comparing the position L0 and the position L1 with a position when measuring a standard liquid.