Patent ID: 12228126

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals will be used for the same elements or elements having the same functions in the following description and redundant description will be omitted.

First, a microdevice system according to the present embodiment will be described with reference toFIGS.1and2.FIG.1is a schematic diagram of a microdevice system.FIG.2is a partially enlarged view of a microfluidic device. A microdevice system1is used for observing a reaction of a captured cell to a target substance, forming a lipid bilayer membrane, or the like. The microdevice system1is, for example, a microfluidic device or a nanofluidic device.

The microdevice system1includes a microfluidic device2and a liquid supply device3. The liquid supply device3supplies a desired liquid to the microfluidic device2. In the present embodiment, the liquid supply device3supplies four types of liquids L1, L2, L3, and L4to the microfluidic device2. For example, the liquid L1is a first liquid, the liquid L2is a second liquid, the liquid L3is a third liquid, and the liquid L4is a fourth liquid.

The microfluidic device2includes cover glass4and a substrate5. The substrate5is stacked on the cover glass4. The substrate5has a pair of main surfaces. As illustrated inFIG.1, the substrate5is provided with a groove where the liquid supplied from the liquid supply device3flows.FIG.1illustrates a cross section parallel to the pair of main surfaces of the substrate5. The substrate5is in contact with the cover glass4on one of the main surfaces. The substrate5is formed of, for example, resin such as silicon rubber. Examples of the material of the silicon rubber include dimethylpolysiloxane. The groove of the substrate5is formed by, for example, photolithography or the like.

The groove provided in the substrate5includes a pair of flow channels10and20, inflow channels11,12,21, and22, outflow channels13and23, and a communication portion30. The flow channels10and20have one end and the other end. One end of the flow channels10and20constitutes a flow channel inlet. The other end of the flow channels10and20constitutes a flow channel outlet. The inflow channels11and12are connected to one end of the flow channel10. The outflow channel13is connected to the other end of the flow channel10. The inflow channels21and22are connected to one end of the flow channel20. The outflow channel23is connected to the other end of the flow channel20. The communication portion30allows the flow channel10and the flow channel20to communicate with each other in the region between one end and the other end of the flow channels10and20.

The pair of flow channels10and20run along each other in a direction D1in parallel to the main surface of the substrate5. In other words, the pair of flow channels10and20pass through a plane parallel to the main surface of the substrate5and are arranged in a direction D2orthogonal to the direction D1on the plane. The flow channel10and the flow channel20are partitioned by the wall that is positioned between the flow channel10and the flow channel20. In the present embodiment, the flow channels10and20are linear. The flow channels10and20may be arcuate.

In the present embodiment, the width of the wall between the flow channel10and the flow channel20is smaller than the width of the flow channels10and20when viewed in a direction D3orthogonal to the main surface of the substrate5. In the present embodiment, the flow channels10and20have a rectangular cross section and the cross-sectional area of the flow channel10and the cross-sectional area of the flow channel20are equal to each other. The flow channel10and the flow channel20also have the same cross-sectional shape. For example, the flow channel20is a second flow channel when the flow channel10is a first flow channel. For example, in the present embodiment, the inflow channel11is a first inflow channel, the inflow channel12is a second inflow channel, the inflow channel21is a third inflow channel, and the inflow channel22is a fourth inflow channel.

The width of the flow channels10and20in the direction D2is, for example, 100 μm. The width of the flow channels10and20in the direction D2may be 50 μm to 2,000 μm. The length of the flow channels10and20is, for example, 7 mm The depth of the flow channels10and20in the direction D3is, for example, 25 μm. The depth of the flow channels10and20in the direction D3may be 15 μm to 30 μm.

As illustrated inFIG.2, the communication portion30includes a recess31provided in the flow channel10, a recess32provided in the flow channel20, and a communication hole33allowing the recess31and the recess32to communicate with each other. The recess31has a U shape recessed toward the flow channel20side when viewed in the direction D3. The recess32has a U shape recessed toward the flow channel10side when viewed in the direction D3. The communication hole33penetrates the bottom surfaces of the U-shaped recesses31and32and allows the flow channel10and the flow channel20to communicate with each other. The communication hole33is provided in the direction D2.

The inflow channels11and12and the outflow channel13have one end and the other end. One end of the inflow channel11includes an injection port11a.The other end of the inflow channel11is connected to the flow channel10. One end of the inflow channel12includes an injection port12a.The other end of the inflow channel12is connected to the flow channel10. One end of the outflow channel13includes an outflow port13a.The other end of the outflow channel13is connected to the flow channel10.

The inflow channels11and12and the outflow channel13are provided at positions farther from the flow channel20than the communication hole33in the direction D2. The inflow channels11and12and the outflow channel13are linear. The inflow channel12runs closer to the flow channel20side than the inflow channel11when viewed in the direction D3. In the present embodiment, the inflow channels11and12and the outflow channel13run in a direction parallel to the main surface of the substrate5and intersecting with an extension direction D1of the flow channels10and20. The inflow channel11is inclined with respect to the extension direction D1of the flow channels10and20at an angle larger than that of the inflow channel12.

The inflow channels21and22and the outflow channel23have one end and the other end. One end of the inflow channel21includes an injection port21a.The other end of the inflow channel21is connected to the flow channel20. One end of the inflow channel22includes an injection port22a.The other end of the inflow channel22is connected to the flow channel20. One end of the outflow channel23includes an outflow port23a.The other end of the outflow channel23is connected to the flow channel20.

The inflow channels21and22and the outflow channel23are provided at positions farther from the flow channel10than the communication hole33in the direction D2. In the present embodiment, the inflow channels21and22and the outflow channel23are linear. The inflow channel21runs closer to the flow channel10side than the inflow channel22when viewed in the direction D3. In the present embodiment, the inflow channels21and22and the outflow channel23run in a direction parallel to the main surface of the substrate5and intersecting with the extension direction D1of the flow channels10and20. The inflow channel22is inclined with respect to the extension direction D1of the flow channels10and20at an angle larger than that of the inflow channel21. The inflow channel21may run in the extension direction D1of the flow channels10and20.

The liquid supply device3includes a supply unit40supplying a liquid to the flow channel10and a supply unit70supplying a liquid to the flow channel20. The supply unit40includes a pump unit41, a branch pipe45, introduction units50and55, and stopping portions60and65. The supply unit70includes a pump unit71, a branch pipe75, introduction units80and85, and stopping portions90and95. For example, in the present embodiment, the introduction unit50is a first introduction unit, the introduction unit55is a second introduction unit, the introduction unit80is a third introduction unit, and the introduction unit85is a fourth introduction unit. For example, the supply unit40is a first supply unit and the supply unit70is a second supply unit.

The pump unit41has a discharge port41afor discharging a fluid F1. The pump unit41is, for example, a syringe pump containing the fluid F1discharged from the discharge port41a.The pump unit41may manually discharge the fluid F1from the discharge port41a.The pump unit41discharges the fluid F1from the discharge port41aat a constant flow rate. The fluid F1is, for example, a first fluid.

The fluid F1discharged from the discharge port41aby the pump unit41is, for example, an incompressible fluid. Examples of the incompressible fluid include a liquid. Examples of the liquid include a buffer solution. The buffer solution may be, for example, phosphate buffered saline (hereinafter, referred to as “PBS”). InFIG.1, the arrow that is illustrated with respect to the supply unit40indicates the flow rate of the fluid F1. InFIG.1, the arrow that is illustrated with respect to the supply unit70indicates the flow rate of a fluid F2. The wider the arrow, the higher the flow rate. It should be noted that “flow rate” is a volumetric flow rate and means a volume per unit time of fluid movement.

The branch pipe45has a connecting portion46and a plurality of pipe portions47and48. In the present embodiment, the branch pipe45has two pipe portions47and48. The connecting portion46is connected to the discharge port41a.The fluid F1discharged from the discharge port41aflows into the branch pipe45from the connecting portion46. In the present embodiment, the syringe pump and the connecting portion46of the branch pipe45are connected by a silicone tube.

The pipe portions47and48branch off from the connecting portion46. Accordingly, the fluid F1that has flowed in from the connecting portion46flows into at least one of the plurality of pipe portions47and48. The flow rate of the fluid F1flowing into the connecting portion46after the branch pipe45is filled with the fluid F1is the total flow rate of the fluid F1flowing out of the pipe portions47and48. Although the branch pipe45branches off from the connecting portion46into the two pipe portions47and48in the present embodiment, it may branch into three or more pipe portions47and48.

The introduction unit50introduces the liquid L1into the flow channel10. The introduction unit50is disposed so as to introduce the liquid L1into the injection port11aof the inflow channel11. The introduction unit50has a configuration for containing the liquid L1. In the present embodiment, the introduction unit50includes an containing pipe51in which the liquid L1is contained. One end of the containing pipe51is connected to the pipe portion47. The other end of the containing pipe51is disposed at the injection port11aof the microfluidic device2. The containing pipe51has a sufficient length in accordance with the volume of the liquid L1to be contained. The containing pipe51is configured in a loop shape in order to save space. In the present embodiment, the introduction unit50contains the liquid L1in the containing pipe51and the volume of the contained liquid L1exceeds the volume of the flow channel10from the connection position between the inflow channel11and the flow channel10to the connection position between the flow channel10and the communication hole33in the extension direction D1. For example, the containing pipe51is a first containing pipe.

The fluid F1that has flowed out of the pipe portion47flows into the containing pipe51. As a result, the liquid L1contained in the containing pipe51is pushed out by the fluid F1that has flowed into the containing pipe51. Specifically, the liquid L1contained in the containing pipe51moves to the side opposite to the pipe portion47in accordance with the volume of the fluid F1that has flowed into the containing pipe51. Accordingly, the flow rate of the liquid L1supplied from the containing pipe51to the flow channel10of the microfluidic device2is the flow rate of the fluid F1flowing out of the pipe portion47. In other words, the introduction unit50introduces the liquid L1into the flow channel10at a flow rate corresponding to the flow rate of the fluid F1flowing through the pipe portion47. The configuration of the supply unit40is not limited to the configuration described above. The flow rate of the liquid L1supplied from the containing pipe51to the flow channel10of the microfluidic device2may be different from the flow rate of the fluid F1flowing out of the pipe portion47.

The introduction unit55introduces the liquid L2into the flow channel10. The introduction unit55is disposed so as to introduce the liquid L2into the injection port12aof the inflow channel12. The introduction unit55has a configuration for containing the liquid L2. In the present embodiment, the introduction unit55includes an containing pipe56in which the liquid L2is contained. In the present embodiment, one end of the containing pipe56is connected to the pipe portion48. The other end of the containing pipe56is disposed at the injection port12aof the microfluidic device2. The containing pipe56has a sufficient length in accordance with the volume of the liquid L2to be contained. The containing pipe56is configured in a loop shape in order to save space. For example, the containing pipe56is a second containing pipe.

The fluid F1that has flowed out of the pipe portion48flows into the containing pipe56. As a result, the liquid L2contained in the containing pipe56is pushed out by the fluid F1that has flowed into the containing pipe56. Specifically, the liquid L2contained in the containing pipe56moves to the side opposite to the pipe portion48in accordance with the volume of the fluid F1that has flowed into the containing pipe56. Accordingly, the flow rate of the liquid L2supplied from the containing pipe56to the flow channel10of the microfluidic device2is the flow rate of the fluid F1flowing out of the pipe portion48. In other words, the introduction unit55introduces the liquid L2into the flow channel10at a flow rate corresponding to the flow rate of the fluid F1flowing through the pipe portion48. The configuration of the supply unit40is not limited to the configuration described above. The flow rate of the liquid L2supplied from the containing pipe56to the flow channel10of the microfluidic device2may be different from the flow rate of the fluid F1flowing out of the pipe portion48.

The stopping portion60stops the flow of the fluid F1in the pipe portion47. The stopping portion65stops the flow of the fluid F1in the pipe portion48. In the present embodiment, the stopping portions60and65include valves61and66opening and closing the flow channels, respectively. The valve61opens and closes the flow channel connecting the pipe portion47and the introduction unit50.

The valve61is provided at the connection part between the pipe portion47and one end of the containing pipe51. The valve66opens and closes the flow channel connecting the pipe portion48and the introduction unit55. The valve66is provided at the connection part between the pipe portion48and one end of the containing pipe56. The valve61may open and close the flow channel connecting the introduction unit50and the microfluidic device2. The valve66may open and close the flow channel connecting the introduction unit55and the microfluidic device2.

The valves61and66may be, for example, MEMS technology-based pneumatic valves provided adjacent to the flow channel through which the fluid F1, the liquid L1, or the liquid L2flows. In this case, the flow channel through which the fluid F1, the liquid L1, or the liquid L2flows is pressed and the flow channel is closed as a result of an increase in air pressure in the pneumatic valve.

The pump unit71has a discharge port71afor discharging the fluid F2. The pump unit71is, for example, a syringe pump containing the fluid F2discharged from the discharge port71a.The pump unit71may manually discharge the fluid F2from the discharge port71a.The pump unit71discharges the fluid F2from the discharge port71aat a constant pressure. The fluid F2is, for example, a second fluid.

The fluid F2discharged from the discharge port71aby the pump unit71is, for example, an incompressible fluid. Examples of the incompressible fluid include a liquid. Examples of the liquid include a buffer solution. The buffer solution may be, for example, PBS.

The branch pipe75has a connecting portion76and a plurality of pipe portions77and78. In the present embodiment, the branch pipe75has two pipe portions77and78. The connecting portion76is connected to the discharge port71a.The fluid F2discharged from the discharge port71aflows into the branch pipe75from the connecting portion76. In the present embodiment, the syringe pump and the connecting portion76of the branch pipe75are connected by a silicone tube. For example, in the present embodiment, the pipe portion47is a first pipe portion, the pipe portion48is a second pipe portion, the pipe portion77is a third pipe portion, and the pipe portion78is a fourth pipe portion.

The pipe portions77and78branch off from the connecting portion76. Accordingly, the fluid F2that has flowed in from the connecting portion76flows into at least one of the pipe portions77and78. The flow rate of the fluid F2flowing into the connecting portion76after the branch pipe75is filled with the fluid F2is the total flow rate of the fluid F2flowing out of the pipe portions77and78. Although the branch pipe75branches off from the connecting portion76into the two pipe portions77and78in the present embodiment, it may branch into three or more pipe portions77and78.

The introduction unit80introduces the liquid L3into the flow channel20. The introduction unit80is disposed so as to introduce the liquid L3into the injection port21aof the inflow channel21. The introduction unit80has a configuration for containing the liquid L3. In the present embodiment, the introduction unit80includes an containing pipe81in which the liquid L3is contained. In the present embodiment, one end of the containing pipe81is connected to the pipe portion77. The other end of the containing pipe81is disposed at the injection port21aof the microfluidic device2. The containing pipe81has a sufficient length in accordance with the volume of the liquid L3to be contained. The containing pipe81is configured in a loop shape in order to save space. For example, the containing pipe81is a third containing pipe.

The fluid F2that has flowed out of the pipe portion77flows into the containing pipe81. As a result, the liquid L3contained in the containing pipe81is pushed out by the fluid F2that has flowed into the containing pipe81. Specifically, the liquid L3contained in the containing pipe81moves to the side opposite to the pipe portion77in accordance with the volume of the fluid F2that has flowed into the containing pipe81. Accordingly, the flow rate of the liquid L3supplied from the containing pipe81to the flow channel20of the microfluidic device2is the flow rate of the fluid F2flowing out of the pipe portion77. In other words, the introduction unit80introduces the liquid L3into the flow channel20at a flow rate corresponding to the flow rate of the fluid F2flowing through the pipe portion77. The configuration of the supply unit70is not limited to the configuration described above. The flow rate of the liquid L3supplied from the containing pipe81to the flow channel20of the microfluidic device2may be different from the flow rate of the fluid F2flowing out of the pipe portion77.

The introduction unit85introduces the liquid L4into the flow channel20. The introduction unit85is disposed so as to introduce the liquid L4into the injection port22aof the inflow channel22. The introduction unit85has a configuration for containing the liquid L4. In the present embodiment, the introduction unit85includes an containing pipe86in which the liquid L4is contained. In the present embodiment, one end of the containing pipe86is connected to the pipe portion78. The other end of the containing pipe86is disposed at the injection port22aof the microfluidic device2. The containing pipe86has a sufficient length in accordance with the volume of the liquid L4to be contained. The containing pipe86is configured in a loop shape in order to save space. In the present embodiment, the introduction unit85contains the liquid L4in the containing pipe86and the volume of the contained liquid L4exceeds the volume of the flow channel20from the connection position between the inflow channel21and the flow channel20to the connection position between the flow channel20and the communication hole33in the extension direction D1. For example, the containing pipe86is a fourth containing pipe.

The fluid F2that has flowed out of the pipe portion78flows into the containing pipe86. As a result, the liquid L4contained in the containing pipe86is pushed out by the fluid F2that has flowed into the containing pipe86. Specifically, the liquid L4contained in the containing pipe86moves to the side opposite to the pipe portion78in accordance with the volume of the fluid F2that has flowed into the containing pipe86. Accordingly, the flow rate of the liquid L4supplied from the containing pipe86to the flow channel20of the microfluidic device2is the flow rate of the fluid F2flowing out of the pipe portion78. In other words, the introduction unit85introduces the liquid L4into the flow channel20at a flow rate corresponding to the flow rate of the fluid F2flowing through the pipe portion78. The configuration of the supply unit70is not limited to the configuration described above. The flow rate of the liquid L4supplied from the containing pipe86to the flow channel20of the microfluidic device2may be different from the flow rate of the fluid F2flowing out of the pipe portion78.

The stopping portion90stops the flow of the fluid F2in the pipe portion77. The stopping portion95stops the flow of the fluid F2in the pipe portion78. In the present embodiment, the stopping portions90and95include valves91and96opening and closing the flow channels, respectively. The valve91opens and closes the flow channel connecting the pipe portion77and the introduction unit80. The valve91is provided at the connection part between the pipe portion77and one end of the containing pipe81. The valve96opens and closes the flow channel connecting the pipe portion78and the introduction unit85. The valve96is provided at the connection part between the pipe portion78and one end of the containing pipe86and. The valve91may open and close the flow channel connecting the introduction unit80and the microfluidic device2. The valve96may open and close the flow channel connecting the introduction unit85and the microfluidic device2.

The valves91and96may be, for example, MEMS technology-based pneumatic valves provided adjacent to the flow channel through which the fluid F2, the liquid L3, or the liquid L4flows. In this case, the flow channel through which the fluid F2, the liquid L3, or the liquid L4flows is pressed and the flow channel is closed as a result of an increase in air pressure in the pneumatic valve.

Next, the liquid supply operation in the microdevice system1will be described in detail with reference toFIGS.1,3, and4. Although only a part of the microfluidic device2and the supply unit40are illustrated inFIGS.3and4, a case where the liquid is supplied to the flow channel20by the supply unit70will also be described along with a case where the liquid is supplied to the flow channel10by the supply unit40.FIG.3illustrates a state where both the valve61and the valve66of the supply unit40are open.FIG.4illustrates a state where the valve66of the supply unit40is closed. InFIGS.3and4, arrows indicate the flow rates of the fluid F1and the liquids L1and L2. The wider the arrow, the higher the flow rate. InFIGS.3and4, two-dot chain lines indicate the boundary between the liquid L1and the liquid L2. The liquid L1and the liquid L2are mixed at this boundary.

As illustrated inFIG.3, in a state where both the valve61and the valve66of the supply unit40are open, the fluid F1introduced from the pump unit41into the branch pipe45flows out of both the pipe portion47and the pipe portion48. In this case, the liquid L1is introduced from the introduction unit50into the inflow channel11and the liquid L2is introduced from the introduction unit55into the inflow channel12. The liquid L1that has flowed through the inflow channel11and the liquid L2that has flowed through the inflow channel12merge at the flow channel10. The merged liquid L1and liquid L2flow through the flow channel10in parallel to each other and in the extension direction D1. In other words, a layer through which the liquid L1flows and a layer through which the liquid L2flows are formed in the flow channel10. When viewed in the direction D3, the liquid L2flows on the flow channel20side. In other words, the flow of the liquid L2is closer to the flow channel20than the flow of the liquid L1in the direction D2. Accordingly, only the liquid L2is supplied to the flow channel10side of the communication hole33.

In a state where both the valve91and the valve96of the supply unit70are open, the fluid F2introduced from the pump unit71into the branch pipe75flows out of both the pipe portion77and the pipe portion78. In this case, the liquid L3is introduced from the introduction unit80into the inflow channel21and the liquid L4is introduced from the introduction unit85into the inflow channel22. The liquid L3that has flowed through the inflow channel21and the liquid L4that has flowed through the inflow channel22merge at the flow channel20. The merged liquid L3and liquid L4flow through the flow channel20in parallel to each other and in the extension direction D1as in the case of the liquids L1and L2. In other words, a layer through which the liquid L3flows and a layer through which the liquid L4flows are formed in the flow channel20. When viewed in the direction D3, the liquid L3flows on the flow channel10side. In other words, the flow of the liquid L3is closer to the flow channel10than the flow of the liquid L4in the direction D2. Accordingly, only the liquid L3is supplied to the flow channel20side of the communication hole33.

As illustrated inFIG.4, in a state where the valve61is open and the valve66is closed, the fluid F1introduced from the pump unit41into the branch pipe45flows out of the pipe portion47and does not flow out of the pipe portion48. Accordingly, the liquid L2is not introduced from the introduction unit55into the inflow channel12although the liquid L1is introduced from the introduction unit50into the inflow channel11. Accordingly, the flow of the liquid L2in the inflow channel12stops and only the liquid L1flows through the flow channel10in the extension direction D1. At this time, the liquid L1flushes the liquid L2remaining in the flow channel10. As a result, only the liquid L1is supplied to the flow channel10side of the communication hole33.

In a state where the valve61is open and the valve66is closed, the flow rate of the fluid F1flowing through the pipe portion47increases as the flow rate of the fluid F1flowing through the pipe portion48decreases. In the present embodiment, the entire fluid F1newly introduced into the branch pipe45from the pump unit41flows out of the pipe portion47. As a result, the flow rate of the fluid F1in the pipe portion47increases from the state where both the valve61and the valve66are open. Accordingly, the flow rate of the liquid L1introduced from the introduction unit50into the inflow channel11also increases from the state where both the valve61and the valve66are open. Accordingly, a change in the flow rate of the liquid flowing in the flow channel10is suppressed and a pressure change in the flow channel10is suppressed even in the event of a switch from the state where both the valve61and the valve66are open to the state where the valve66is closed.

In a state where the valve96is open and the valve91is closed, the fluid F2introduced from the pump unit71into the branch pipe75flows out of the pipe portion78and does not flow out of the pipe portion77. Accordingly, the liquid L3is not introduced from the introduction unit80into the inflow channel21although the liquid L4is introduced from the introduction unit85into the inflow channel22. Accordingly, the flow of the liquid L3in the inflow channel21stops and only the liquid L4flows through the flow channel20in the extension direction D1. At this time, the liquid L4flushes the liquid L3remaining in the flow channel20. As a result, only the liquid L4is supplied to the flow channel20side of the communication hole33.

In a state where the valve96is open and the valve91is closed, the flow rate of the fluid F2flowing through the pipe portion78increases as the flow rate of the fluid F2flowing through the pipe portion77decreases. In the present embodiment, the entire fluid F2newly introduced into the branch pipe75from the pump unit71flows out of the pipe portion78. As a result, the flow rate of the fluid F2in the pipe portion78increases from the state where both the valve91and the valve96are open. Accordingly, the flow rate of the liquid L4introduced from the introduction unit85into the inflow channel22also increases from the state where both the valve91and the valve96are open. Accordingly, a pressure change in the flow channel20is suppressed even in the event of a switch from the state where both the valve91and the valve96are open to the state where the valve91is closed.

Next, a method for using the microdevice system in the present embodiment will be described. In the present embodiment, a case where the microdevice system1is used for observing a cell reaction to a target substance will be described. In the present embodiment, the liquids L1and L3are, for example, buffer solutions. This buffer solution may be, for example, HBS buffer (140 mM NaCl, 5 mM KCl, 2 mM CaCl2, 1 mM MgCl2, 10 mM glucose, 0.2% bovine serum albumin (BSA), and 10 mM HEPES (pH 7.4)). The liquid L2is a suspension containing a plurality of cells (hereinafter, referred to as “cell suspension”). The liquid L4is a sample containing a target substance to be brought into contact with a cell (hereinafter, simply referred to as “sample”). The liquid L1does not contain cells. The liquid L3does not contain the target substance. F1uorescent dyes may be added to the liquids L1, L2, L3, and L4so that the respective flows are confirmed.

The diameter of the communication hole33of the microfluidic device2in the present embodiment is smaller than the diameter of the cell. For example, the diameter of the communication hole33is less than 75% of the cell diameter. For example, the diameter of the communication hole33is 1 to 15 μm. In the present embodiment, the diameter of the communication hole33is 3 μm.

The cell used in the present embodiment has a fluorescent indicator.

The target substance is not particularly limited and may be a stimulant such as ATP and histamine.

The fluorescent indicator is not particularly limited insofar as it is a substance that fluoresces as a result of stimulation by the target substance. The fluorescent indicator may be, for example, a fluorescent protein or a fluorescent dye. Preferably, the fluorescent indicator is a genetically encoded fluorescent protein. When the stimulation by the target substance results in, for example, a change in intracellular ion concentration, the fluorescent indicator may be a fluorescent protein or a fluorescent dye sensitive to the ion. Examples of the fluorescent protein include GCaMP3, GCaMP6s, and GCaMP7 proteins as calcium-sensitive fluorescent proteins. Examples of the fluorescent dye include calcium-sensitive fluorescent dyes such as F1uo 3-AM, Rhod 2-AM, Calbryte (trademark) 520, F1uo 4-AM, Fura 2-AM, Indo 1-AM, Calbryte 590, and Calbryte 630.

The cells are, for example, human cervical epithelial cancer cells HeLa.

Next, a method for supplying a liquid to the microfluidic device2in the present embodiment will be described with reference toFIGS.5to9.FIG.5is a flowchart illustrating the method for supplying the liquid to the microfluidic device2in the present embodiment.FIGS.6to9are diagrams for describing each step of the method for supplying the liquid to the microfluidic device2. InFIGS.6to9, arrows indicate the flow direction of the liquid. InFIGS.6to8, two-dot chain lines indicate the boundary between different liquids. The different liquids are mixed at this boundary.

First, as illustrated inFIG.5, the liquid supply device3for liquid supply to the microfluidic device2is prepared (process S11). Specifically, the introduction unit50is disposed so as to introduce the buffer solution as the liquid L1into the injection port11a of the inflow channel11. The introduction unit55is disposed so as to introduce the cell suspension as the liquid L2into the injection port12aof the inflow channel12. The introduction unit80is disposed so as to introduce the buffer solution as the liquid L3into the injection port21aof the inflow channel21. The introduction unit85is disposed so as to introduce the sample as the liquid L4into the injection port22aof the inflow channel22.

Subsequently, as illustrated inFIG.5, the fluids F1and F2are introduced into the pipe portions47,48,77, and78by the pump units41and71(process S12). Specifically, the fluid F1is discharged at a constant flow rate from the discharge port41aof the pump unit41of the supply unit40and the fluid F1is caused to flow into the pipe portions47and48. The fluid F2is discharged at a constant flow rate from the discharge port71aof the pump unit71of the supply unit70and the fluid F2is caused to flow into the pipe portions77and78. At this time, the valves61,66,91, and96are open without exception. As a result, as illustrated inFIG.6, the liquids L1and L2are introduced into the flow channel10and the liquids L3and L4are introduced into the flow channel20by the liquid supply device3. The buffer solution and the cell suspension flow in parallel through the flow channel10such that the cell suspension flows closer to the flow channel20than the buffer solution. The buffer solution and the sample flow in parallel through the flow channel20such that the buffer solution flows closer to the flow channel10than the sample. In other words, a layer through which the buffer solution flows and a layer through which the cell suspension flows are formed in the flow channel10. A layer through which the buffer solution flows and a layer through which the sample flows are formed in the flow channel20.

In the present embodiment, the fluids F1and F2are discharged from the pump unit41of the supply unit40and the pump unit71of the supply unit70such that the pressure in the flow channel10becomes higher than the pressure in the flow channel20. Accordingly, a pressure difference occurs in the communication hole33. As a result of this pressure difference, a cell α in the liquid L2is captured at the communication hole33on the flow channel10side as illustrated inFIG.7. It should be noted that “pressure” in the flow channel means a static pressure. Accordingly, “pressure difference” is the difference in static pressure between the flow channels.

In the present embodiment, the pressure in the flow channel10becomes higher than the pressure in the flow channel20owing to the difference between the total flow rate of the liquids L1and L2flowing through the flow channel10and the total flow rate of the liquids L3and L4flowing through the flow channel20. However, the pressure in the flow channel10may become higher than the pressure in the flow channel20owing to the difference in shape between the flow channel10and the flow channel20instead of the difference between the flow rate flowing through the flow channel10and the flow rate of the flow channel20. In the process S12, the total flow rate of the liquids L1and L2flowing through the flow channel10is 60 μL/h. The total flow rate of the liquids L3and L4flowing through the flow channel20is 40 μL/h.

Subsequently, as illustrated inFIG.5, the cell suspension introduction into the flow channel10is stopped (process S13). Specifically, the valve66is closed and the flow of the fluid F1in the pipe portion48is stopped while the fluid F1is caused to flow into the pipe portion47. The fluid F2flows in the pipe portions77and78. As a result, as illustrated inFIG.8, only the buffer solution as the liquid L1flows through the flow channel10and the cell α not captured at the communication hole33is washed away. As in the case of the process S12, the buffer solution and the sample as the liquids L3and L4flow in parallel in the flow channel20.

The flow rate of the fluid F1discharged by the pump unit41of the supply unit40and the flow rate of the fluid F2discharged by the pump unit71of the supply unit70in the process S12are maintained in the process S13. Since the valve66is closed and the flow of the fluid F1in the pipe portion48is stopped, the flow rate of the fluid F1in the pipe portion47increases by the flow rate of the fluid F1flowing in the pipe portion48in the process S12. As a result, the flow rate of the buffer solution flowing through the flow channel10increases by the flow rate of the cell suspension flowing through the flow channel10in the process S12. Accordingly, a pressure change in the flow channel10is suppressed regardless of the switch from the process S12to the process S13.

Subsequently, as illustrated inFIG.5, the buffer solution introduction into the flow channel20is stopped (process S14). Specifically, the valve91is closed and the flow of the fluid F2in the pipe portion77is stopped while the fluid F2is caused to flow into the pipe portion78. The fluid F1flows in the pipe portion47. The flow of the fluid F1in the pipe portion48is stopped. As a result, as illustrated inFIG.9, only the sample as the liquid L4flows into the flow channel20and the sample containing the target substance also flows into the communication hole33side of the flow channel20. Accordingly, through the communication hole33, the target substance comes into contact with the cell α captured by the communication hole33. As a result, the reaction of the cell α to the target substance is initiated.

The flow rate of the fluid F1discharged by the pump unit41of the supply unit40and the flow rate of the fluid F2discharged by the pump unit71of the supply unit70in the process S12and the process S13are maintained in the process S14. Since the valve91is closed and the flow of the fluid F2in the pipe portion77is stopped, the flow rate of the fluid F2in the pipe portion78increases by the flow rate of the fluid F2flowing in the pipe portion77in the process S12and the process S13. As a result, the flow rate of the sample flowing through the flow channel20increases by the flow rate of the buffer solution flowing through the flow channel20in the process S12and the process S13. Accordingly, a pressure change in the flow channel20is suppressed regardless of the switch from the process S13to the process S14.

Next, a method for using the microdevice system according to a modification example of the present embodiment will be described. Described in this modification example is a case where the microdevice system1is used for lipid bilayer membrane formation. The microdevice system in this modification example is generally similar or identical to the embodiment described above. In the microdevice system of this modification example, the diameter of the communication hole33of the microfluidic device2and the types of the liquids L1, L2, L3, and L4are different from those of the embodiment described above. Hereinafter, the differences between the above-described embodiment and the modification example will be mainly described.

The diameter of the communication hole33of the microfluidic device2in this modification example is larger than the diameter of the communication hole33in the embodiment described above. For example, the upper limit of the diameter of the communication hole33in this modification example is equal to or less than the depth of the flow channels10and20. In other words, the diameter of the communication hole33may be 100 μm insofar as the depth of the flow channels10and20is 100 μm. In the microfluidic device2of this modification example, the diameter of the communication hole33may be, for example, 1 to 30 μm. In this modification example, the diameter of the communication hole33is 10 μm. The liquids L2and L3are lipid-dissolved oily solutions (hereinafter, simply referred to as “oily solutions”). The liquids L1and L4are aqueous solutions. F1uorescent dyes may be added to the liquids L1, L2, L3, and L4so that the respective flows are confirmed.

The lipid is a component forming a lipid bilayer membrane and has a hydrophilic group (hydrophilic atomic group) and a hydrophobic group (hydrophobic atomic group). The lipid is appropriately selected depending on the lipid bilayer membrane to be formed. The lipid is, for example, phospholipid, glycolipid, cholesterol, or another compound. Examples of the phospholipid include phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, and sphingomyelin. Examples of the glycolipid include cerebroside and ganglioside.

Various organic solvents are appropriately selected as an oily solvent for lipid dissolution. Examples of the oily organic solvent include hexadecane and squalene.

The aqueous solution of the liquids L1and L4is, for example, a buffer solution. The buffer solution may be, for example, PBS. The aqueous solution of the liquids L1and L4contains various components that do not affect the lipid bilayer membrane formation.

Next, a method for supplying a liquid to the microfluidic device2in this modification example will be described with reference toFIGS.10to13.FIG.10is a flowchart illustrating the method for supplying the liquid to the microfluidic device2in this modification example.FIGS.11to13are diagrams for describing each step of the method for supplying the liquid to the microfluidic device2. InFIGS.11to13, arrows indicate the flow direction of the liquid. InFIGS.11and12, two-dot chain lines indicate the boundary between different liquids. The different liquids are mixed at this boundary.

First, as illustrated inFIG.10, the liquid supply device3for liquid supply to the microfluidic device2is prepared (process S21). Specifically, the introduction unit50is disposed so as to introduce the aqueous solution as the liquid L1into the injection port11aof the inflow channel11. The introduction unit55is disposed so as to introduce the oily solution as the liquid L2into the injection port12aof the inflow channel12. The introduction unit80is disposed so as to introduce the oily solution as the liquid L3into the injection port21aof the inflow channel21. The introduction unit85is disposed so as to introduce the aqueous solution as the liquid L4into the injection port22aof the inflow channel22.

Subsequently, as illustrated inFIG.10, the fluids F1and F2are introduced into the pipe portions47,48,77, and78by the pump units41and71(process S22). Specifically, the fluid F1is discharged at a constant flow rate from the discharge port41aof the pump unit41of the supply unit40and the fluid F1is caused to flow into the pipe portions47and48. The fluid F2is discharged at a constant flow rate from the discharge port71aof the pump unit71of the supply unit70and the fluid F2is caused to flow into the pipe portions77and78. At this time, the valves61,66,91, and96are open without exception. As a result, as illustrated inFIG.11, the liquids L1and L2are introduced into the flow channel10and the liquids L3and L4are introduced into the flow channel20by the liquid supply device3. The aqueous solution and the oily solution flow in parallel through the flow channel10such that the oily solution flows closer to the flow channel20than the aqueous solution. The oily solution and the aqueous solution flow in parallel through the flow channel20such that the oily solution flows closer to the flow channel10than the aqueous solution. In other words, a layer through which the aqueous solution flows and a layer through which the oily solution flows are formed in each of the flow channel10and the flow channel20.

In this modification example, the fluids F1and F2are discharged from the pump unit41of the supply unit40and the pump unit71of the supply unit70such that the pressure in the flow channel10and the pressure in the flow channel20become equal to each other. This “equal” includes a case where a pressure difference occurs to the extent that the lipid membrane formed in the communication hole33is not crushed. It should be noted that “pressure” in the flow channel means a static pressure. Accordingly, “pressure difference” is the difference in static pressure between the flow channels.

In this modification example, the pressure in the flow channel10and the pressure in the flow channel20are equal to each other by the total flow rate of the liquids L1and L2flowing through the flow channel10and the total flow rate of the liquids L3and L4flowing through the flow channel20being equal to each other. However, even with the flow rate flowing through the flow channel10and the flow rate of the flow channel20different from each other, the pressure in the flow channel10may be equal to the pressure in the flow channel20by the flow channel10and the flow channel20having different shapes. In the process S22, the total flow rate of the liquids L1and L2flowing through the flow channel10is 10 μL/h. The total flow rate of the liquids L3and L4flowing through the flow channel20is 10 μL/h.

Subsequently, as illustrated inFIG.10, the oil and fat solution introduction into the flow channel10is stopped (process S23). Specifically, the valve66is closed and the flow of the fluid F1in the pipe portion48is stopped while the fluid F1is caused to flow into the pipe portion47. The fluid F2flows in the pipe portions77and78. As a result, as illustrated inFIG.12, only the aqueous solution as the liquid L1flows through the flow channel10and the oily solution in the flow channel10is washed away. Accordingly, the aqueous solution is supplied to the flow channel10side of the communication hole33and the interface between the aqueous solution of the liquid L1and the oily solution of the liquid L3is formed in the communication hole33. At the interface, a single molecule lipid membrane in which a hydrophilic group is arranged toward the aqueous solution side is formed in the communication hole33. As in the case of the process S22, the aqueous solution and the oily solution as the liquids L3and L4flow in parallel in the flow channel20.

The flow rate of the fluid F1discharged by the pump unit41of the supply unit40and the flow rate of the fluid F2discharged by the pump unit71of the supply unit70in the process S22are maintained in the process S23. Since the valve66is closed and the flow of the fluid F1in the pipe portion48is stopped, the flow rate of the fluid F1in the pipe portion47increases by the flow rate of the fluid F1flowing in the pipe portion48in the process S22. As a result, the flow rate of the aqueous solution flowing through the flow channel10increases by the flow rate of the oily solution flowing through the flow channel10in the process S22. Accordingly, a pressure change in the flow channel10is suppressed regardless of the switch from the process S22to the process S23.

Subsequently, as illustrated inFIG.10, the oily solution introduction into the flow channel20is stopped (process S24). Specifically, the valve91is closed and the flow of the fluid F2in the pipe portion77is stopped while the fluid F2is caused to flow into the pipe portion78. The fluid F1flows in the pipe portion47. The flow of the fluid F1in the pipe portion48is stopped. As a result, as illustrated inFIG.13, only the aqueous solution as the liquid L4flows into the flow channel20and the oily solution in the flow channel20is washed away. At this time, the hydrophobic group of a lipid β in the oily solution is disposed in the hydrophobic group of the single molecule lipid membrane formed in the communication hole33and a lipid bilayer membrane is formed in the communication hole33. The formed lipid bilayer membrane has a structure in which the hydrophobic groups of two lipid molecules are oriented so as to face each other in a tail-to-tail manner.

The flow rate of the fluid F1discharged by the pump unit41of the supply unit40and the flow rate of the fluid F2discharged by the pump unit71of the supply unit70in the process S22are maintained in the process S24. Since the valve91is closed and the flow of the fluid F2in the pipe portion77is stopped, the flow rate of the fluid F2in the pipe portion78increases by the flow rate of the fluid F2flowing in the pipe portion77in the process S23. As a result, the flow rate of the aqueous solution flowing through the flow channel20increases by the flow rate of the oily solution flowing through the flow channel20in the process S23. Accordingly, a pressure change in the flow channel20is suppressed regardless of the switch from the process S23to the process S24.

As described above, in the supply unit40, the introduction unit55introduces the liquid L2into the flow channel10at a flow rate corresponding to the flow rate of the fluid F1flowing through the pipe portion48. Accordingly, the introduction of the liquid L2into the flow channel10is stopped by the flow of the fluid F1in the pipe portion48being stopped. In a state where the flow of the fluid F1in the pipe portion48is stopped, the fluid F1discharged from the discharge port41aof the pump unit41flows into a part of the branch pipe45other than the pipe portion48. In the branch pipe45, the pipe portions47and48branch off from the connecting portion46, and thus the flow rate of the fluid F1in the pipe portion47in the state where the flow of the fluid F1in the pipe portion48is stopped increases as compared with a state where the flow of the fluid F1in the pipe portion48is not stopped. In the embodiment and the modification example described above, the fluid F1flows into the pipe portion47by the flow rate that does not flow into the pipe portion48. The introduction unit50introduces the liquid L1into the flow channel10at a flow rate corresponding to the flow rate of the fluid F1flowing through the pipe portion47. Accordingly, a change in the total flow rate of the liquids L1and L2flowing through the flow channel10is suppressed even in the case of transition between the state where the flow of the fluid F1in the pipe portion48is stopped and the state where the flow of the fluid F1in the pipe portion48is not stopped. Accordingly, in the liquid supply device3, a change in pressure in the flow channel10is suppressed even in the case of transition between the state where the flow of the fluid F1in the pipe portion48is stopped and the state where the flow of the fluid F1in the pipe portion48is not stopped. As a result, it is possible to suppress a change in the pressure difference between the flow channel10and the flow channel20with a simple configuration and without electronically controlling the amounts of introduction of the liquids L1and L2.

The supply unit70is similar in configuration to the supply unit40. Accordingly, a change in pressure in the flow channel20is suppressed even in the case of transition between a state where the flow of the fluid F2in the pipe portion77is stopped and a state where the flow of the fluid F2in the pipe portion77is not stopped. As a result, it is possible to suppress a change in the pressure difference between the flow channel10and the flow channel20with a simple configuration and without electronically controlling the amounts of introduction of the liquids L1, L2, L3, and L4.

The introduction unit50includes the containing pipe51connected to the pipe portion47and containing the liquid L1. The introduction unit55includes the containing pipe56connected to the pipe portion48and containing the liquid L2. Accordingly, the liquid L1contained in the containing pipe51is pushed out in accordance with the flow rate of the fluid F1flowing through the pipe portion47. The liquid L2contained in the containing pipe56is pushed out in accordance with the flow rate of the fluid F1flowing through the pipe portion48. As a result, it is possible to suppress a change in the pressure difference between the flow channel10and the flow channel20with a simpler configuration.

The stopping portion65includes the valve66opening and closing the flow channel connecting the pipe portion48and the introduction unit55. Accordingly, the flow of the fluid F1in the pipe portion48can be easily stopped by the valve66. Insofar as the valve66is provided between the introduction unit55and the pipe portion48, the fluid F1from the pump unit41flows into the pipe portion47without being affected by the compressibility of the liquid L2, flow channel expansion in the introduction unit55, and so on when the flow of the fluid F1of the pipe portion48is stopped by the valve66. Accordingly, a change in pressure in the flow channel10is further suppressed.

The microfluidic device2has the inflow channels11and12connected to the flow channel10. The inflow channels11and12are disposed at positions farther from the flow channel20than the communication hole33in the direction D2. The inflow channel12runs closer to the flow channel20side than the inflow channel11when viewed in the direction D3. The introduction unit50is disposed so as to introduce the liquid L1into the inflow channel11. The introduction unit55is disposed so as to introduce the liquid L2into the inflow channel12. In this case, a layer through which the liquid L1flows and a layer through which the liquid L2flows are formed in the flow channel10by the liquids L1and L2being introduced into the inflow channels11and12, respectively. With this configuration, it is possible to control the liquid supplied to the communication hole33depending on whether or not the liquid L2is introduced into the inflow channel12.

The microfluidic device2has the inflow channels21and22connected to the flow channel20. The inflow channels21and22are disposed at positions farther from the flow channel10than the communication hole33in the direction D2. The inflow channel21runs closer to the flow channel10side than the inflow channel22when viewed in the direction D3. The introduction unit80is disposed so as to introduce the liquid L3into the inflow channel21. The introduction unit85is disposed so as to introduce the liquid L4into the inflow channel22. In this case, a layer through which the liquid L3flows and a layer through which the liquid L4flows are formed in the flow channel20by the liquids L3and L4being introduced into the inflow channels21and22, respectively. With this configuration, it is possible to control the liquid supplied to the communication hole33depending on whether or not the liquid L3is introduced.

The diameter of the communication hole33is 1 to 15 μm. In this case, the cell α can be captured by the communication hole33by a pressure difference being provided between the flow channel10and the flow channel20.

In the liquid supply method described above, the liquids L1and L2are introduced into the flow channel10in the step of causing the fluid to flow into the pipe portions47and48. In the step of stopping the flow of the fluid F1in the pipe portion48, the liquid L1is introduced into the flow channel10without the liquid L2being introduced. In a state where the flow of the fluid F1in the pipe portion48is stopped, the fluid F1discharged from the discharge port41aof the pump unit41flows into a part of the branch pipe45other than the pipe portion48. Accordingly, the flow rate of the fluid F1in the pipe portion47in the state where the flow of the fluid F1in the pipe portion48is stopped increases as compared with a state where the flow of the fluid F1in the pipe portion48is not stopped. Accordingly, in the liquid supply method described above, a change in pressure in the flow channel10is suppressed between the step of causing the fluid F1to flow into the pipe portions47and48and the step of stopping the flow of the fluid F1in the pipe portion48. As a result, it is possible to suppress a change in the pressure difference between the flow channel10and the flow channel20with a simple configuration and without electronically controlling the amounts of introduction of the liquids L1and L2.

In the step of causing the fluid to flow into the pipe portions47and48, the liquid L1and the liquid L2are caused to flow in parallel such that the liquid L2flows closer to the flow channel20than the liquid L1in the flow channel10. In this case, the liquid supplied to the communication hole33can be controlled between the step of causing the fluid F1to flow into the pipe portions47and48and the step of stopping the flow of the fluid F1in the pipe portion48.

In the step of causing the fluid F2to flow into the pipe portions77and78, the liquids L3and L4are introduced into the flow channel20. In the step of stopping the flow of the fluid F2in the pipe portion77, the liquid L4is introduced into the flow channel20without the liquid L3being introduced. Even in a state where the flow of the fluid in the pipe portion77is stopped, the fluid discharged from the discharge port71aof the pump unit71flows into a part of the branch pipe75other than the pipe portion77. Accordingly, the flow rate of the fluid F2in the pipe portion78in the state where the flow of the fluid F2in the pipe portion77is stopped increases as compared with a state where the flow of the fluid F2in the pipe portion77is not stopped. Accordingly, in the liquid supply method described above, a change in pressure in the flow channel20is suppressed between the step of causing the fluid F2to flow into the pipe portions77and78and the step of stopping the flow of the fluid F2in the pipe portion77. As a result, it is possible to suppress a change in the pressure difference between the flow channel10and the flow channel20with a simple configuration and without electronically controlling the amounts of introduction of the liquids L1, L2, L3, and L4.

In the step of causing the fluid F2to flow into the pipe portions77and78, the liquid L3and the liquid L4are caused to flow in parallel such that the liquid L3flows closer to the flow channel10than the liquid L4in the flow channel20. In this case, the liquid supplied to the communication hole33can be controlled between the step of causing the fluid F2to flow into the pipe portions77and78and the step of stopping the flow of the fluid F2in the pipe portion77.

In the embodiment described above, the liquid L2is a suspension containing the plurality of cells α. The liquid L4may be a sample containing a target substance to be brought into contact with the cell α. In the step of causing the fluid F1to flow into the pipe portions47and48and the step of causing the fluid F2to flow into the pipe portions77and78, the fluids F1and F2are discharged from the pump unit41of the supply unit40and the pump unit71of the supply unit70such that the pressure in the flow channel10becomes higher than the pressure in the flow channel20. The flow rate of the fluid F1discharged by the pump unit41of the supply unit40and the flow rate of the fluid F2discharged by the pump unit71of the supply unit70in the step of causing the fluid F1to flow into the pipe portions47and48and the step of causing the fluid F2to flow into the pipe portions77and78are maintained in the step of stopping the flow of the fluid F1in the pipe portion48.

In this case, the cell α can be captured on the flow channel10side of the communication hole33. In the step of stopping the flow of the fluid F2in the pipe portion77, the target substance is capable of being brought into contact with the captured cell α. In the step of stopping the flow of the fluid F1in the pipe portion48, a change in the pressure difference between the flow channel10and the flow channel20is suppressed. Accordingly, the captured cell α is prevented from being unintentionally detached from the communication hole33and the captured cell a is prevented from being pressed against the communication hole33and crushed.

The flow rate of the fluid F1discharged by the pump unit41of the supply unit40and the flow rate of the fluid F2discharged by the pump unit71of the supply unit70in the step of causing the fluid F1to flow into the pipe portions47and48and the step of causing the fluid F2to flow into the pipe portions77and78are maintained in the step of stopping the flow of the fluid F2in the pipe portion77. In this case, a change in the pressure difference between the flow channel10and the flow channel20is suppressed in the step of stopping the flow of the fluid F2in the pipe portion77. Accordingly, the captured cell a is prevented from being unintentionally detached from the communication hole33and the captured cell α is prevented from being pressed against the communication hole33and crushed.

In the modification example described above, the liquid L4is an aqueous solution. The liquid L3is an oily solution in which the lipid β is dissolved. The liquid supply step includes a step of supplying the aqueous solution to the flow channel10before the step of stopping the flow of the fluid F2in the pipe portion77. In the step of causing the fluid F2to flow into the pipe portions77and78and the step of supplying the aqueous solution to the flow channel10, the fluid F1and the fluid F2are discharged from the pump unit41of the supply unit40and the pump unit71of the supply unit70such that the pressure in the flow channel10and the pressure in the flow channel20become equal to each other. The flow rate of the fluid F1discharged by the pump unit41of the supply unit40and the flow rate of the fluid F2discharged by the pump unit71of the supply unit70in the step of causing the fluid F2to flow into the pipe portions77and78and the step of supplying the aqueous solution to the flow channel10are maintained in the step of stopping the flow of the fluid F2in the pipe portion77. In this case, a single molecule lipid membrane is formed in the communication hole33before the flow of the fluid F2in the pipe portion77is stopped and a lipid bilayer membrane is formed in the communication hole33in the step of stopping the flow of the fluid F2in the pipe portion77. A change in the pressure difference between the flow channel10and the flow channel20is suppressed in the step of stopping the flow of the fluid F2in the pipe portion77. Accordingly, the formed lipid membrane is prevented from being crushed.

Although an embodiment and a modification example of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiment and modification example. Various modifications can be made within the gist thereof.

For example, the shape of the communication portion30is not limited to the shapes described in the above-described embodiment and modification example. The communication portion30may include a slit allowing the flow channel10and the flow channel20to communicate with each other instead of the communication hole33. In this case, “diameter of the communication hole33” described in the embodiment and the modification example should be read as “slit width of the communication portion30”.

The number of the pipe portions branching off from the connecting portion46in the branch pipe45is not limited to two. The number of the pipe portions branching off from the connecting portion76in the branch pipe75is not limited to two. The liquid supply device3may be provided with introduction units connected to the pipe portions, the introduction units may be equal in number to the pipe portions of the branch pipes45and75, and each pipe portion may be provided with a stopping portion.

The inflow channels11,12,21, and22of the flow channels10and20are not limited to two in number. Three or more inflow channels may be connected to each of the flow channels10and20.

The microfluidic device2may have a plurality of the communication portions30allowing the flow channel10and the flow channel20to communicate with each other.

The liquid supply device3may supply a liquid to only one of the flow channels10and20. In this case, either the supply unit40or the supply unit70may not be used.

The fluids F1and F2discharged from the discharge ports41aand71amay be gases. The compressibility of a gas is greater than the compressibility of a liquid. Accordingly, when the fluids F1and F2discharged from the discharge ports41aand71aare liquids, the amounts of the liquids L1, L2, L3, and L4supplied to the microfluidic device2as a result of the operation of the pump units41and71are adjusted with higher accuracy than when the fluids F1and F2are gases. In the above-described embodiment and modification example, the liquid supply device3is configured such that gas does not enter from the pump units41and71to the flow channels10and20.

Various liquids may be disposed in the microfluidic device2before the fluids F1and F2are discharged from the pump unit41and the pump unit71. For example, the liquid L1may be disposed at a part of the inflow channel11and the flow channel10, the liquid L2may be disposed at a part of the inflow channel12and the flow channel10, the liquid L3may be disposed at a part of the inflow channel21and the flow channel20, and the liquid L4may be disposed at a part of the inflow channel22and the flow channel20, before the operation of the pump unit41and the pump unit71. In this case, the layer of the liquid L1and the layer of the liquid L2may be formed in advance in the flow channel10. The layer of the liquid L3and the layer of the liquid L4may be formed in advance in the flow channel20.

The introduction units50,55,80, and85containing the liquids L1, L2, L3, and L4are not limited to a tubular member directly connected to the branch pipes45and75as in the case of the containing pipes51,56,81, and86. For example, the introduction units50,55,80, and85may be syringes discharging the respective liquids L1, L2, L3, and L4with the pressure applied from the fluids F1and F2discharged from the pipe portions47,48,77, and78.

The supply unit40may lack the stopping portion60. The supply unit70may lack the stopping portion95.

The stopping portions60,65,90, and95may be provided at one end or both ends of the containing pipes51,56,81, and86, respectively. The stopping portions60,65,90, and95may be provided in the middle of the flow channels of the containing pipes51,56,81, and86, respectively.

The stopping portions60,65,90, and95are not limited to a configuration stopping a fluid flow by means of a valve. For example, the stopping portions60,65,90, and95may include an elastic tube instead of the valve and the elastic tube may constitute a part of the flow channel from the pipe portions47,48,77, and78to the microfluidic device2. The stopping portions60,65,90, and95may be configured to close a part of the flow channel from the pipe portions47,48,77, and78to the microfluidic device2by, for example, the elastic tube being bent manually.

REFERENCE SIGNS LIST

1: microdevice system,2: microfluidic device,3: liquid supply device,10,20: flow channel,11,12,21,22: inflow channel,33: communication hole,40,70: supply unit,41,71: pump unit,41a,71a:discharge port,45,75: branch pipe,46,76: connecting portion,47,48,77,78: pipe portion,50,55,80,85: introduction unit,51,56,81,86: containing pipe,60,65,90,95: stopping portion,61,66,91,96: valve, F1, F2: fluid, L1, L2, L3, L4: liquid, D1, D2, D3: direction, α: cell, β: lipid.