Flow passage structure, micro flow passage device, and wearable device

Abstract

To provide a technique of suppressing influence of air bubbles generated from liquid in a micro flow passage device.SOLUTION: One of flow passage structures according to the present invention is a flow passage structure constituting a part of a micro flow passage device. The flow passage structure includes: an inflow passage into which liquid flows; a liquid reservoir part connected to the inflow passage; a gas reservoir part provided upward in a vertical direction of the liquid reservoir part; and an outflow passage connected to the liquid reservoir part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a flow channel structure, a microflow channel device, and a wearable device. [Background technology]

[0002] Microfluidic devices have micrometer-sized channels and are used to process or manipulate liquids within the channels. Applications of microfluidic devices include DNA analysis and cell analysis. Compared to conventional devices, microfluidic devices have the advantage of being able to use smaller amounts of chemicals, samples, and reagents for testing and analysis, and in recent years, technological developments have been made regarding the manufacture of microfluidic devices and testing methods.

[0003] In tests and analyses using microchannel devices, processes are performed to manipulate the flow of liquid by branching, expanding, or contracting the flow channel, or to heat the liquid using a heater or the like, and the reactions to these processes are sensed. Here, gas dissolved in the liquid may be generated as bubbles during the process. The bubbles may have a significant effect on the measurement results, for example, by staying in the flow channel and obstructing the flow, or by adhering to the sensing part and obstructing normal testing. For example, the following Patent Documents 1 and 2 are cited as technologies for suppressing the effects of bubbles in such microchannels.

[0004] Patent Document 1 aims to reduce the risk of air bubbles becoming mixed into liquid when the liquid is flowed through the flow path in a flow path device, and discloses the following content regarding the flow path device: "One embodiment of a flow path device according to the present invention comprises a flow path, and a first space and a second space located in the flow path. The flow path has a side along the direction in which the liquid flows. The second space is connected to the first space. The upper end of the second space is located at a different height from the upper end of the first space. At least a part of the first space is located between the side of the flow path and at least a part of the outer periphery of the second space." Patent Document 2 aims to provide a micro-channel chip capable of removing air bubbles generated in a micro-channel and preventing the elution of adhesive components into the channel to suppress reaction inhibition of the solution in the channel, and a method for manufacturing the same, and discloses the following as the micro-channel chip and the method for manufacturing the micro-channel chip: "Micro-channel chip 1 comprises substrate 10, partition layer 11 forming a channel on substrate 10, and upper cover layer 12 formed on the surface of partition layer 11 opposite substrate 10 and serving as a lid for channel section 3, upper cover layer 12 is provided with air bubble removal section 7 which is part of upper cover layer 12 and removes air bubbles generated in channel section 3, and no adhesive layer is provided between partition layer 11 and upper cover layer 12." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2021 / 107003 [Patent Document 2] JP 2023-18620 A Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, prevention of air bubbles from being mixed into the liquid flowing through the flow path is considered, but air bubbles generated within the flow path are not considered. Also, in Patent Document 2, the air bubble removal unit is applied when the micro flow path has a specific structure, and there is still room for consideration for micro flow paths having other structures. Therefore, an object of the present invention is to provide a technique for suppressing the effects of air bubbles generated from liquid in a microchannel device. [Means for solving the problem]

[0007] In order to solve the above problems, one representative flow path structure of the present invention is a flow path structure constituting a part of a microflow path device, characterized in that the flow path structure comprises an inflow flow path through which a liquid flows, a liquid reservoir connected to the inflow flow path, a gas reservoir provided vertically upward from the liquid reservoir, and an outflow flow path connected to the liquid reservoir. Effect of the Invention

[0008] According to the present invention, it is possible to suppress the influence of air bubbles generated from the liquid in the microchannel device. Problems, configurations and effects other than those described above will become apparent from the following description of the preferred embodiment of the invention. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a schematic diagram of a flow path structure of the first embodiment. [Diagram 2] FIG. 2 is a diagram showing the control process of the inlet and outlet valves. [Diagram 3] FIG. 3 is a schematic diagram showing the forces acting on a bubble. [Figure 4] FIG. 4 is a flow chart showing the operation of the inlet and outlet valves. [Diagram 5] FIG. 5 is a diagram showing a schematic diagram of a flow channel structure of the second embodiment. [Figure 6] FIG. 6 is a flowchart showing the operation of the flow path structure of the second embodiment. [Figure 7] FIG. 7 is a diagram illustrating a wearable device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiment. In addition, in the description of the drawings, the same parts are denoted by the same reference numerals.

[0011] In addition, in order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings. In addition, in this disclosure, "upper" refers to the vertically upward direction when a plate-like member or layer is placed horizontally. Furthermore, "upper" and its opposite, "lower", may be referred to as the "positive z-axis direction" and the "negative z-axis direction". Furthermore, the distance in the z-axis direction may be referred to as the "height", and the distance in the x-axis direction or the y-axis direction may be referred to as the "width". Furthermore, the part in the negative z-axis direction and parallel to the z-axis direction may be referred to as the "bottom". Additionally, the terms "planar shape" and "plan view" refer to the shape of a surface or layer when viewed from above. Furthermore, the terms "cross-sectional shape" and "cross-sectional view" refer to the shape of a plate-like member or layer when cut in a specific direction and viewed from the horizontal direction.

[0012] Furthermore, the term "liquid" refers to a liquid reagent, a solvent containing a solute, etc. It is not limited to a liquid only, but also includes a viscous state and a state in which a liquid and a solid are mixed.

[0013] (Cause of air bubbles) The reason why bubbles form in a liquid is because the amount of gas dissolved in the liquid exceeds the saturation solubility. In general, the saturation solubility varies depending on the type of solution, the type of gas, and the temperature and pressure at which the solution and gas exist.

[0014] When a microfluidic device is used for testing and analysis, for example, a liquid is heated and a reaction is analyzed. As the temperature increases, the saturated solubility of a gas generally decreases, and the excess dissolved gas appears as bubbles.

[0015] When a gas is dissolved in a liquid that exceeds the saturation solubility, it is called supersaturation. When a liquid is supersaturated, the gas forms bubbles when the liquid is vibrated or stirred.

[0016] Example 1 (Flow path structure) First, the channel structure of the microchannel device will be described with reference to FIG. Fig. 1 is a diagram showing a schematic diagram of a flow channel structure of Example 1, Fig. 1(a) shows a plan view of the flow channel structure 1, and Fig. 1(b) shows a cross-sectional view of the flow channel structure 1. The flow channel structure 1 constitutes a part of a micro flow channel device, and includes an inflow channel 10 through which a liquid flows, a liquid reservoir 11 connected to the inflow channel 10, a gas reservoir 12 provided vertically upward of the liquid reservoir 11, and an outflow channel 13 connected to the liquid reservoir 11. A specific description will be given below.

[0017] In Fig. 1, the arrow fd indicates the flow direction, and in the example of Fig. 1, the liquid flows from the minus x direction to the plus x direction. Therefore, when devices for performing inspection, analysis, etc. are provided ahead of the flow direction fd, the flow path structure 1 is provided upstream of these devices.

[0018] The flow channel structure 1 is not limited by the shape, use, material, etc. of the microchannel device, and can be applied to any microchannel device. For example, the flow channel structure 1 of the present disclosure can be applied even when the microchannel device is composed of a first substrate and a second substrate, and the flow channel is composed of a groove in the first substrate and the second substrate attached to the first substrate so as to cover the groove. In addition, two or more flow channel structures 1 can be provided in the microchannel device.

[0019] The inflow flow path 10 is connected to the upstream side of the liquid pool 11, and introduces the liquid into the liquid pool 11. The liquid pool 11 is a space that retains the liquid introduced from the inflow flow path 10. The outflow flow path 13 is connected to the downstream side of the liquid pool 11, and the liquid retained in the liquid pool 11 flows out. An inlet valve 14 is provided between the inlet flow path 10 and the liquid pool 11, and an outlet valve 15 is provided between the liquid pool 11 and the outlet flow path 13. When the outlet valve 15 is closed, communication between the liquid pool 11 and the outlet flow path 13 is blocked. When the outlet valve 15 changes from a closed state to an open state, the outlet valve 15 has a structure that opens so that the opening widens from the bottom side of the outlet flow path 13. The inlet valve 14 and the outlet valve 15 will be described later.

[0020] In a cross-sectional view perpendicular to the flow direction fd, the liquid pool 11 has a larger flow area than the inflow flow path 10 and the outflow flow path 13. Specifically, as shown in FIG. 1(a), the liquid pool 11 has a width (for example, a width indicated by width W2) larger than the width W1 of the inflow flow path 10 and the outflow flow path 13, and has an arc-shaped outer shape with a continuously changing width. Also, as shown in FIG. 1(b), the inflow flow path 10, the liquid pool 11, and the outflow flow path 13 share a bottom. When this bottom is used as a reference, the height H of the liquid pool 11 is approximately the same as or higher than the height h1 of the inflow flow path 10, and is higher than the height h2 of the outflow flow path 13. Incidentally, when the bottom of the microchannel device is placed horizontally, the liquid level of the outflow flow path 13 is lower than the liquid level of the inflow flow path 10. In this way, since the flow path area of ​​the liquid pool 11 is larger than the flow path area of ​​the inflow flow path 10, it is possible to reduce the flow rate of the liquid when the liquid is introduced from the inflow flow path 10 to the liquid pool 11. Also, since the flow area of ​​the liquid pool 11 is larger than the flow path area of ​​the inflow flow path 10, it is possible to retain the liquid in the liquid pool 11. Also, since the flow path area of ​​the liquid pool 11 is larger than the flow path area of ​​the outflow flow path 13, it is possible to suppress the outflow amount of the liquid retained in the liquid pool 11 without flowing out to the outflow flow path 13 all at once.

[0021] Moreover, the liquid pool 11 is disposed between the inlet valve 14 and the outlet valve 15, and has a length D1. In a section of length D2 from the inlet valve 14 in the positive x-axis direction, the liquid pool 11 has a connecting flow path 11a having the same shape as the inlet flow path 10. If the liquid were to be introduced directly from the inlet flow path 10 to the liquid pool 11 without providing the connecting flow path 11a, the change in the flow path would be large, and sudden turbulence would occur in the liquid, which could result in secondary generation of air bubbles. By providing the connecting flow path 11a, a buffer section is formed between the inlet flow path 10 and the liquid pool 11, making it possible to suppress the effect on the flow of the liquid.

[0022] Although the shape of the liquid reservoir 11 has been described above, the present disclosure is not limited thereto. The shape of the liquid reservoir 11 may be any shape that has a function of retaining liquid. In addition, since the flow channel structure 1 is incorporated into the flow channel of the micro flow channel device, the structures of the inflow flow channel 10 and the outflow flow channel 13 can also be adapted to match the structure of the micro flow channel device. For example, the cross sections of the inflow flow channel 10 and the outflow flow channel 13 in the direction perpendicular to the flow direction fd may be rectangular or circular. In addition, a shape suitable for the flow channel structure 1 can be appropriately selected.

[0023] The gas reservoir 12 is provided vertically upward (in the positive z-axis direction) of the liquid reservoir 11, and is a space in which gas can exist. Bubbles generated from the liquid retained in the liquid reservoir 11 become gas and are released from the liquid into the gas reservoir 12. As shown by the angle θ1 in FIG. 1(b), the gas reservoir 12 is configured so that the space narrows toward the flow direction fd. This shape makes it possible to prevent the gas retained in the gas reservoir 12 from re-entering the outflow flow path 13.

[0024] Although the shape of the gas accumulation portion 12 has been described above, the present disclosure is not limited thereto. The shape of the gas accumulation portion 12 may be any shape that has the function of retaining gas. The gas accumulation portion 12 retains bubbles or gas generated while the liquid is retained in the liquid accumulation portion 11. If the liquid penetrates into the gas accumulation portion 12 while the liquid is retained in the liquid accumulation portion 11 and the gas accumulation portion 12 is filled with liquid, the function of the gas accumulation portion 12 may not be exerted. Even if the gas is retained in the gas accumulation portion 12 once, when the pressure of the gas accumulation portion 12 increases, the gas in the gas accumulation portion 12 may dissolve again into the liquid. The shape of the gas accumulation portion 12 is set in consideration of the type of liquid, the flow rate of the liquid, the size of the microchannel device, and the like.

[0025] The flow path structure 1 may also include other components, such as a sensor for measuring the flow velocity of the liquid, a sensor for measuring the flow rate, a drive mechanism for driving the inlet valve 14 and the outlet valve 15, a heating member for heating the liquid, and the like.

[0026] (Effects of liquid and gas pools) While the liquid is temporarily retained in the liquid reservoir 11, bubbles generated from the liquid rise up in the liquid. For this reason, bubbles or liquid containing many bubbles is present on the upper side of the liquid reservoir 11, mainly near the liquid surface, while liquid from which the bubbles have been removed is present on the lower side of the liquid reservoir 11. The bubbles collected on the upper side of the liquid reservoir 11 are held as gas in the gas reservoir 12, and are prevented from dissolving back into the liquid. In this way, the flow path structure 1 can extract the liquid from which the bubbles have been removed and flow it downstream by utilizing the property of bubbles rising up without the application of any external force.

[0027] Furthermore, when electrochemical measurements are performed using a microfluidic device, the measurement sensitivity may deteriorate if air bubbles adhere to the measurement sensor. By providing the liquid reservoir 11 and the gas reservoir 12 as in the present disclosure, the liquid from which air bubbles have been removed can reach the sensor, thereby suppressing the effect of air bubbles on the measurement.

[0028] (Inlet and outlet valve control) Next, the control of the inlet valve 14 and the outlet valve 15 will be described with reference to FIGS. The influence of air bubbles can be further suppressed by controlling inflow valve 14 and outflow valve 15 in addition to liquid reservoir 11 and gas reservoir 12. Inflow valve 14 and outflow valve 15 are adjustment valves capable of controlling the flow of liquid, and manipulating inflow valve 14 and outflow valve 15 promotes the induction of air bubbles generated from the liquid to the upper side of liquid reservoir 11. Note that, for example, solenoid valves can be applied as inflow valve 14 and outflow valve 15, but the present disclosure is not limited to the case of solenoid valves.

[0029] Fig. 2 is a diagram showing the control process of the inlet valve 14 and the outlet valve 15. Fig. 2 shows the process performed from time t=0 to t=t6, and also shows the process from the generation of bubbles to their removal. Note that in Fig. 2, the dimensions of the components included in the flow path structure 1 are changed for ease of understanding, but the present disclosure is not limited to the embodiment in Fig. 2.

[0030] Moreover, the flow path structure 1 further includes an absorbing member that absorbs gas in the gas pool portion 12. FIG. 2 shows an example in which a remover 43 is provided as an absorbing member at the boundary portion between the liquid pool portion 11 and the gas pool portion 12. Here, the remover 43 can be set according to the type of gas contained in the bubbles. For example, when it is expected that bubbles 40 containing carbon dioxide will be generated, it is possible to set a remover 43 containing activated carbon. As a method of installation, for example, a film-like absorbing member such as an absorption sheet can be used. The relationship between the generated gas and the absorbent is shown in the following table. Basically, it is possible to place a solid as the absorbent 43, but when a liquid absorbent is used, it is possible to hold the liquid absorbent in a hydrophilic and water-absorbent member and then place it in the flow path structure 1. In addition, when a sheet that absorbs VOCs (volatile organic compounds) is used as the absorbing member, it is also advantageous in terms of reducing the environmental load. [Table 1]

[0031] In FIG. 2, t=0 indicates the time when the bubble 40 occurs. The bubble factor section 41 is a location where there is a cause for generating bubbles from the liquid, and indicates a location where the bubble 40 can occur. The bubble factor section 41 may be, for example, a heat source for heating the liquid, a structure provided on the flow path for stirring the liquid, or a location where a user operation is input and vibration is applied. When the bubble is generated by the bubble factor section 41, the flow velocity meter 42 measures the flow velocity of the liquid. The flow velocity of the bubble 40 is treated as being the same as v0, which is the flow velocity of the liquid. The generation of the bubble 40 may be determined by using the occurrence of a causative event as a trigger, or it can also be determined by detecting the bubble 40 itself. After the bubble 40 is generated in the bubble factor section 41, it flows through the inflow flow path 10 having a length L.

[0032] At t=t1, the air bubbles 40 flow through the inlet flow path 10 and reach the inlet valve 14. In this case, the outlet valve 15 is closed to block the flow path, and the liquid containing the air bubbles 40 is prevented from flowing into the outlet flow path 13.

[0033] Here, a method for deriving t1 will be described with reference to Fig. 3. Fig. 3 is a diagram showing the forces acting on the air bubble 40. In Fig. 3, of the main forces acting on the air bubble 40, buoyancy F1, gravity F2, and fluid resistance F3 are shown. Note that ρ f is the density of the liquid [kg / m 3 ], V g is the volume of bubble 40 [m 3 ], g is the gravitational acceleration [m / s 2 ], ρ g is the density of bubble 40 [kg / m 3 ], C d is the resistance coefficient, A g is the reference area of ​​bubble 40 [m 2 ], v f is the liquid flow velocity [m / s]. The reference area is the cross-sectional area of ​​the bubble, which is the projected area in the flow direction fd.

[0034] The air bubble 40 in the liquid is subjected to buoyancy F1 (a force that tries to rise) caused by the difference in density between the liquid and the gas, gravity F2 (a force that acts vertically downward), and drag F3 caused by the viscosity of the liquid. The buoyancy F1 is proportional to the volume V of the air bubble 40. g The drag force F3 is proportional to the cross-sectional area (projected area) of the bubble A g and velocity v f Generally, the buoyancy F1 is greater than the gravity F2, and the bubble 40 rises vertically upward in the liquid. Here, the volume V of the sphere is g is proportional to the cube of the radius, and the cross-sectional area A g is proportional to the square, so when the bubble radius becomes larger, the cross-sectional area A g Compared to the increase in volume V g In other words, as the radius of the bubble 40 increases, the buoyancy F1 increases more than the drag F3, so that larger bubbles have the tendency to rise faster.

[0035] Here, when only the force acting in the flow direction fd of the air bubble 40 is considered, the following equation of motion (1) is derived for the x-axis direction.

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[0036] In this case, at t=0, the velocity of the bubble is v x = v0, and the distance traveled by the bubble from the bubble source 41 (in other words, the distance traveled by the bubble from the end of the inflow channel 10) is x = 0. Also, at t = t1, v x =v f Let x = L. By solving equation (1) under these conditions, t1 is derived as equation (2).

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[0037] If we substitute the following values ​​into the variables and calculate equation (2), we get t1 = 1.048 [s]. Bubble density ρ g :1.293[kg / m 3 ] (Air density when bubbles are air) fluid density ρ f :997[kg / m 3 ] (Density of water when the liquid is water) Bubble volume V g :5×10 -4 x5x10 -4 x3.14=7.85x10 -7 [m 3 ] (Assuming bubble diameter is 1mm) Initial bubble velocity v0: 0.01 [m / s] flow velocity v f :0.01[m / s] Drag coefficient C d :0.45[-] Length of inlet flow passage 10: L: 0.02 [m] Reference area A g :3.14×(1×10 -3 )2 / 4=7.85×10 -7 [m 2 ]

[0038] t=t2 indicates a state in which the inlet valve 14 is closed and the flow path is blocked. This causes the liquid containing the bubbles 40 to accumulate in the liquid reservoir 11. t2 may be the same time as t1, or may be, for example, a time when the operation of the outlet valve 15 is started after the inlet valve 14 has completely blocked the flow path at t1. t2 may be set in consideration of the flow velocity v0 so that the liquid containing the bubbles 40 can be prevented from flowing out into the outlet flow path 13.

[0039] t=t3 indicates a case where the liquid containing the air bubbles 40 is retained in the liquid pool 11. By retaining the liquid containing the air bubbles 40 in the liquid pool 11 between t2 and t3, it is possible to cause the air bubbles 40 to float to the upper side of the liquid pool 11.

[0040] Referring now to FIG. 3, the time t taken for the air bubble 40 to move from the bottom of the liquid pool 11 to the liquid surface is 3a Assume that an air bubble is present at the bottom of the liquid pool 11 at t=t2, and that the air bubble rises to the upper side of the liquid pool 11 at t=t3. The following equation of motion (3) is derived for the vertical direction.

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[0041] In this case, at t=0, the velocity of the bubble is v z The distance traveled by the air bubble from the bottom of the liquid pool 11 is z=0. Also, t=t 3a In this case, z = H. By solving equation (3) under these conditions, we obtain equation (4) for t 3a is derived.

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[0042] If we substitute the following values ​​for the variables and calculate equation (4), t 3a =0.00163[s]. Bubble density ρ g :1.293[kg / m 3 ] fluid density ρ f :997[kg / m 3 ] Gravitational acceleration g:9.8[m / s 2 ] Height of liquid pool 11: H: 0.01 [m]

[0043] t 3a is the maximum time required for the air bubble 40 to reach the upper side of the liquid pool 11. 3a By keeping inflow valve 14 closed during this time, it is possible to allow air bubbles 40 to reach the upper side of liquid pool 11. Note that a backflow of liquid may occur between inflow valve 14 and inflow channel 10.

[0044] Referring to FIG. 2, t=t4 indicates a case where the air bubbles 40 are removed. The air bubbles 40 that reach the upper side of the liquid pool 11 are absorbed by the remover 43. Although the case where the remover 43 is installed is shown here, the present disclosure is not limited to this. It is also possible to install only the gas pool 12 without providing the remover 43, or to install a gas permeable membrane between the liquid pool 11 and the gas pool 12. The gas permeable membrane allows gas to permeate from the liquid pool 11 to the gas pool 12, but does not allow liquid to permeate. The gas permeable membrane can prevent liquid from leaking into the discharge mechanism 21. In addition, the air bubbles 40 may be removed by retaining the gas released from the air bubbles 40 in the gas pool 12.

[0045] The time required to remove the air bubbles 40, in other words the time from t3 to t4, can be set depending on the method of removing the air bubbles 40. Note that there may be cases where t3 and t4 are the same.

[0046] At t=t5, the outflow valve 15 is opened. The liquid retained in the liquid reservoir 11 is now in a state in which the air bubbles 40 have been removed, and is discharged to the outflow channel 13.

[0047] At t=t6, the inlet valve 14 is opened, and the liquid flows into the liquid reservoir 11. If air bubbles are generated, the process from t=0 to t=t6 is repeated again.

[0048] Here, we estimate the time required for one cycle from t=0 to t=t6. If the time from t1 to t2, the time from t3 to t4, the time from t4 to t5, and the time from t5 to t6 are each 1 [s], then one cycle is 5.05963 [s]. Although the addition of flow channel structure 1 may affect the flow of liquid through the microchannel device, the effect is thought to be negligible since the time required for one cycle is approximately 5 [s].

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[0049] (Flowchart of adjusting valve control) FIG. 4 is a flow chart showing the operation of the inlet valve 14 and the outlet valve 15.

[0050] First, in step S1, liquid is introduced into a microchannel device having a channel structure 1. Then, in step S2, the flow velocity of the liquid is measured immediately after bubbles are generated by the bubble-causing unit 41. The time at this point is defined as time t=0.

[0051] Next, in step S3, when the air bubble 40 reaches the inlet valve 14, the inlet valve 14 and the outlet valve are closed to retain the liquid containing the air bubble in the liquid reservoir 11. Step S3 corresponds to the control performed at time t1 or t2.

[0052] Next, in step S4, air bubbles 40 are caused to rise to the upper side of liquid pool portion 11 and are removed by remover 43. Step S4 corresponds to control performed at times t3 and t4.

[0053] Next, in step S5, outflow valve 15 is opened to drain the liquid within liquid reservoir 11. Step S5 corresponds to the control performed at time t5.

[0054] Next, in step S6, the inlet valve 14 is opened. Step S6 corresponds to the control performed at time t6.

[0055] (Effect of controlling the inlet and outlet valves) By controlling the inlet valve 14 and the outlet valve 15, it is possible to secure a period of time for the liquid to remain in the liquid pool 11 and for the air bubbles to rise to the upper side of the liquid pool 11. In addition, by opening the outlet valve 15 before the air bubbles dissolve again in the liquid, it is possible to discharge the liquid from which the air bubbles have been removed to the outlet flow path 13. In addition, in the liquid pool 11, the liquid at the upper side is more likely to have air bubbles remaining than the liquid at the lower side. For this reason, the flow path flowing downstream from the outlet valve 15 is made lower than the flow path on the upstream side, so that the lower liquid containing as few air bubbles as possible can be discharged. In other words, the height h2 of the outlet flow path 13 is made lower than the height h1 of the inlet flow path 10, and the height h2 is made lower than the height H of the liquid pool 11, so that the lower liquid containing no air bubbles can be discharged as much as possible. By repeatedly and appropriately controlling the inlet valve 14 and the outlet valve 15, the liquid from which the air bubbles have been removed can be discharged downstream without worrying about the generation of air bubbles.

[0056] The flow velocity of the liquid decreases when passing through the liquid pool 11. Since the kinetic energy of the liquid decreases when the liquid flows out of the flow path structure 1, it is possible to suppress secondary generation of bubbles downstream of the flow path structure 1.

[0057] Example 2 Example 2 differs from Example 1 in that a discharge mechanism 21 is provided in the gas accumulation portion 12 and that a partition member 22 is provided instead of the outflow valve 15. In the following description, components that are the same as or equivalent to those in Example 1 described above are given the same reference numerals, and the description thereof will be simplified or omitted.

[0058] (Flow path structure) The flow channel structure of the microchannel device of Example 2 will be described with reference to Fig. 5. Fig. 5 is a schematic diagram of the flow channel structure of Example 2. Fig. 5(a) shows a plan view of the flow channel structure 1a, and Fig. 5(b) shows a cross-sectional view of the flow channel structure 1a. Fig. 5(a) is a cross-sectional view taken along line AA' in Fig. 5(b). Fig. 5(c) is a cross-sectional view taken along line AA' in Fig. 5(b) in a direction perpendicular to the flow direction fd, focusing in particular on the partition member 22. Fig. 5(c) is a cross-sectional view taken along line BB' in Fig. 5(b).

[0059] In the second embodiment, the bottom of the liquid reservoir 11 is at a different height from the bottom of the inflow channel 10 and the bottom of the outflow channel 13. When the bottom of the liquid reservoir 11 is taken as the reference, the bottom of the inflow channel 10 is at a height d1. The bottom of the outflow channel 13 is at a height d2. The height d1 is greater than the height d2. The width (size in the xy plane) and height (size in the xz plane) of the inlet flow path 10 and the outlet flow path 13 may be the same as in Example 1, or may be set in accordance with the configuration of the flow path structure 1a.

[0060] The exhaust mechanism 21 is a mechanism that opens the space of the gas accumulation portion 12 to the outside of the microchannel device. The exhaust mechanism 21 is, for example, an exhaust path that is connected to the outside of the microchannel device. Compared to the case where a gas absorbing member such as a remover is used, the exhaust mechanism has the advantage that it can be used for a long period of time without the need for replacement of the member.

[0061] The partition member 22 is provided in the liquid pool 11 and has a surface extending in a direction perpendicular to the flow direction fd. In a cross-sectional view perpendicular to the flow direction fd, the partition member 22 covers an area including the liquid level height wd, which is the liquid level reached by the liquid remaining in the liquid pool, and the shape of the partition member 22 changes so that the area covering the liquid pool 11 narrows as it moves vertically downward from the liquid level height wd. Specifically, the liquid pool 11 has a trapezoidal shape as shown in FIG. 5(c). An upper base 22a of the trapezoid is located in the gas pool 12 and has a width larger than the width W3 of the liquid pool 11 and the gas pool 12. A lower base 22b of the trapezoid is located inside the liquid pool 11 and has a width smaller than the width W3. As shown in FIG. 5(c), the partition member 22 does not completely close the liquid pool 11, and a gap 25 through which liquid can flow is formed between the partition member 22 and the side of the liquid pool 11. As shown in FIG. 5(b), the partition member 22 is provided in the liquid pool 11 on a side closer to the outflow passage 13 than to the inflow passage 10.

[0062] The cleaning flow path 23 is a flow path for introducing a cleaning liquid. For example, when introducing a different liquid into the microchannel device, the cleaning liquid is caused to flow through the cleaning flow path 23 into the liquid reservoir 11 in order to wash away the liquid remaining in the liquid reservoir 11. It is also assumed that a sensor is installed in the liquid reservoir 11. In order to clean the sensor, the cleaning liquid is caused to flow through the cleaning flow path 23 into the liquid reservoir 11. Note that while the microchannel device is being used, a stopper 24 blocks the gap between the cleaning flow path 23 and the liquid reservoir 11.

[0063] (Operation of Example 2) Next, the operation of the flow path structure 1a of Example 2 will be described. In the first step, the inflow valve 14 is opened and liquid is introduced into the liquid reservoir 11 through the inflow flow path 10. At this point, the stopper 24 of the cleaning flow path 23 is closed in advance to prevent the liquid from flowing out.

[0064] In the second step, the introduction of the liquid continues, and the liquid is accumulated in the liquid pool 11. At this time, because a step of height d1 is provided between the bottom of the inflow channel 10 and the bottom of the liquid pool 11, the liquid gains momentum when it is introduced from the inflow channel 10 into the liquid pool 11. This causes the liquid to be agitated in the liquid pool 11, making it easier for bubbles to be generated. Due to their nature, bubbles gradually rise to the surface of the liquid accumulated in the liquid pool 11.

[0065] Partition member 22 is provided in liquid pool 11 so as to separate the space inside liquid pool 11 up to a position slightly higher than the height of outflow channel 13. Specifically, when the bottom of liquid pool 11 is used as a reference, height pd of partition member 22 is higher than the height of outflow channel 13 (a height similar to height wd of the liquid surface in liquid pool 11). This is to prevent air bubbles generated in gas pool 12 from flowing out toward outflow channel 13 as much as possible.

[0066] However, when viewed from the flow direction fd, if the partition member 22 completely separates the liquid pool 11 and has a height that reaches the gas pool 12, when the liquid overflows from the upper side of the partition member 22 to the outflow flow path 13 side, the liquid may be agitated to generate air bubbles, which may increase the number of air bubbles. To avoid such a case, as shown in Fig. 5(c), the partition member 22 has a shape that forms a gap 25, which is an area between the partition member 22 and the liquid pool 11, and allows a certain amount of liquid to flow in and out through this gap 25. There is a possibility that air bubbles will move from the gap 25 to the outflow flow path 13 side, but the effect is considered to be negligible.

[0067] Moreover, since the air bubbles gradually rise up from the liquid pooled in the liquid pool 11, there are more of them on the upper side of the liquid pool 11 than on the lower side. The upper side of the partition member 22 is structured to prevent the liquid from overflowing from the liquid pool 11 into the outflow flow path 13, and the lower side is structured to allow the liquid pooled in the liquid pool 11 to properly flow out into the outflow flow path 13.

[0068] In addition, in Fig. 5(b), the liquid level wd of the liquid pool 11 and the height of the outflow flow path 13 (the liquid level in the outflow flow path 13) are substantially the same, but the present disclosure is not limited to this. It is also possible to make the liquid level of the liquid pool 11 and the liquid level of the outflow flow path 13 different. Also, as shown in Fig. 5(c), the gap 25 has a shape that is symmetrical with respect to the partition member 22, but the present disclosure is not limited to this. The size, shape, and position of the gap 25 can be set according to the properties of the liquid and the structure of the liquid pool 11.

[0069] Continuing with the explanation of the operation, in the third step, when the liquid accumulates in the liquid pool 11 up to the height of the outflow flow path 13, the inflow valve 14 is closed a little to reduce the opening of the inflow valve 14. By doing so, the amount of liquid flowing into the liquid pool 11 can be reduced. The state of the liquid accumulated in the liquid pool 11 approaches a stationary state, and a situation is created in which air bubbles are likely to rise to the liquid surface. Note that if the inflow valve 14 is completely closed, liquid may flow in forcefully when the inflow valve 14 is opened again, which may create a situation in which air bubbles are likely to be generated. The generated air bubbles basically accumulate in the liquid pool 11, so the impact is small, but there is a possibility that the air bubbles may leak to the outflow flow path 13 side. For this reason, it is preferable to avoid completely closing the inflow valve 14.

[0070] Next, in a fourth step, the air bubbles that have accumulated near the liquid surface of the liquid pool 11 are discharged to the outside of the flow path structure 1a using a discharge mechanism. Specifically, the gas generated from the air bubbles is discharged from the discharge mechanism 21 to the outside of the micro flow path device including the flow path structure 1a. In addition, if the gas is likely to remain near the liquid surface of the liquid pool 11, it is also possible to place an absorbing member such as a remover near the liquid surface and allow the absorbing member to adsorb the gas.

[0071] Next, in a fifth step, the liquid that has accumulated in the liquid pool 11 up to the same height as the outflow flow path 13 is drained into the outflow flow path 13. That is, of the liquid that has accumulated in the liquid pool 11, the liquid that has exceeded the height of the bottom of the outflow flow path 13 is drained from the outflow flow path 13, and the outflowing liquid has had air bubbles removed.

[0072] Next, in a sixth step, it is detected that the liquid level in the liquid pool 11 drops and liquid no longer flows out from the liquid pool 11 to the outflow flow path 13. If the liquid is not discharged to the outflow flow path 13, the inflow valve 14 is opened and the operation is repeated from the first step.

[0073] Furthermore, if the inlet valve 14 is left closed, liquid will remain in the liquid pool 11, so in order to drain the liquid, the stopper 24 of the cleaning flow path 23 will be opened and the liquid in the liquid pool 11 will be drained.

[0074] (Flowchart of operation in the second embodiment) Next, the operation of the second embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing the operation of the flow path structure 1a of the second embodiment.

[0075] First, in step S20, a liquid is introduced into a microchannel device including a channel structure 1a.

[0076] Next, in step S21, inlet valve 14 is opened to introduce liquid into liquid reservoir 11. Step S21 corresponds to the first step.

[0077] Then, in step S22, the introduction of the liquid continues. Step S22 corresponds to the above-mentioned second step.

[0078] Next, in step S23, it is detected whether or not the liquid flows out into the outflow channel 13. If no outflow is detected (No in step S23), the injection of the liquid in step S22 is continued. If outflow is detected (Yes in step S23), the process proceeds to step S24.

[0079] In step S24, the opening of the inlet valve 14 is adjusted to be smaller. Step S24 corresponds to the third step.

[0080] While the opening of the inlet valve 14 is being adjusted to be small, air bubbles generated in the liquid reservoir 11 are removed (step S25, fourth step). Specifically, the gas generated from the air bubbles is discharged to the outside of the microchannel device by the discharge mechanism 21. Moreover, the gas remaining near the liquid surface of the liquid reservoir 11 is adsorbed by an absorbent such as a remover. Moreover, the liquid is discharged from the liquid reservoir 11 to the outflow channel 13 (step S26, fifth step).

[0081] Next, in step S27, it is detected whether liquid flows out from the liquid pool 11 to the outflow flow path 13. Step S27 corresponds to the sixth step. If liquid no longer flows out (No in step S27), the process returns to step S21 again, and the inflow valve 14 is opened to inject liquid. If liquid flows out (Yes in step S27), the detection in step S27 is performed again.

[0082] (Effects of Example 2) The flow path structure 1a is provided with a liquid pool 11 that temporarily pools liquid ahead of the inflow flow path 10 in the flow direction fd. When the liquid pool 11 is filled with liquid, the liquid naturally flows to the outflow flow path 13. Since the flow rate of the liquid passing through the outflow flow path 13 is suppressed, it is possible to suppress secondary generation of air bubbles when the liquid passes through the outflow flow path 13.

[0083] Furthermore, partition member 22 is provided on a side of liquid pool 11 closer to outflow passage 13 than inflow passage 10. By increasing the distance that the liquid injected into liquid pool 11 travels to reach partition member 22, the liquid can be retained in liquid pool 11 for as long as possible, ensuring a period during which air bubbles can be removed. Furthermore, by adjusting the opening of inflow valve 14, a state close to a stationary state is created in liquid pool 11, making it possible to more effectively remove air bubbles.

[0084] Example 3 Example 3 shows a case where a microfluidic device having a flow channel structure according to the present disclosure is used in a wearable device, which may be used for, for example, so-called health care monitoring, such as testing and analyzing components of sweat (e.g., cortisol, etc.) generated from the human body. In the following description, the microfluidic device is used in a manner in which it is attached to the human body, but the present disclosure is not limited to this. The microfluidic device can also be used as a sensor that acquires human body information in a non-contact or unconstrained manner.

[0085] A wearable device of Example 3 will be described with reference to FIG. 7. FIG. 7 is a diagram showing a wearable device of Example 3. FIG. 7(a) shows a cross section of the wearable device, and FIG. 7(b) shows a state in which the wearable device is used. The wearable device 300 is equipped with a microchannel device having a channel structure according to the present disclosure, and includes a holding mechanism 30 that holds the gas pool 12 so that it faces vertically upward relative to the liquid pool 11. A specific description will be given below.

[0086] FIG. 7(a) shows a cross-sectional view of a wearable device 300. The wearable device 300 has a liquid pool 11 and a gas pool 12 in the flow channel structure 1 or 1a of the mounted micro-channel device, and a holding mechanism 30. The holding mechanism 30 has a roller portion 31 and a support portion 32. Here, in order to explain the positional relationship between the liquid pool 11 and the gas pool 12, the flow channel configuration and the configuration of the micro-channel device are omitted. For example, a glass member or a resin member constituting the micro-channel device may be present between the liquid pool 11 and the holding mechanism 30, but these are omitted in FIG. 7. In addition, in order to explain the positional relationship between the liquid pool 11 and the gas pool 12, the structure of the holding mechanism 30 is omitted in detail.

[0087] Liquid pool 11 is positioned vertically upward relative to gas pool 12. Establishing such a positional relationship causes air bubbles generated in liquid pool 11 to rise to the upper side of liquid pool 11 and are removed in liquid pool 11, and gas remaining in gas pool 12 is removed. In order for wearable device 300 to function, it is necessary to maintain the positional relationship between liquid pool 11 and gas pool 12 in the vertical direction.

[0088] 7(b) shows a case where the wearable device 300 is attached to the human body 33. The human body 33 is a part of the human body, and may be, for example, the wrist, fingers, head, neck, etc., depending on the aspect of the wearable device. It is not limited to being in direct contact with the human skin, and may be attached to clothing worn by the human.

[0089] The roller portion 31 is located between the liquid pool portion 11 and the support portion 32. The roller portion 31 is a rolling element that rotates around the x-axis direction. While four roller portions 31 are shown in FIG. 7, each roller portion 31 is disposed at a predetermined position of the support portion 32.

[0090] The support part 32 is fixed to the human body 33. As shown in (1) and (2) of FIG. 7(b), when the orientation of the human body 33 changes, the orientation of the support part 32 also changes according to the human body 33. Meanwhile, the liquid pool part 11 and the gas pool part 12 move on the roller part 31 along the shape of the support part 32. When moving, the gas pool part 12 is maintained in a state of being positioned vertically upward with respect to the liquid pool part 11. It is also possible to arrange a weight member at a position facing the gas pool part 12 through the liquid pool part 11, so that when the orientation of the wearable device 300 changes, the weight member moves vertically downward, making it easier for the gas pool part 12 to maintain a vertically upward position. Also, FIG. 7 shows an example of the configuration, and the present disclosure is not limited thereto. The configuration and shape of the roller part 31 and the support part 32 can also be set appropriately.

[0091] (Effects of Example 3) Generally, the orientation of a wearable device changes in response to the movement of the human body while it is being used, which may make it difficult to utilize the function of the gas reservoir, which is the space above the flow path structure described in the first and second embodiments of the present disclosure.

[0092] In contrast, the wearable device of Example 3 has a holding mechanism 30 having a support portion 32 on which a roller portion 31 is arranged. When a change occurs in the body of the person wearing the wearable device, the liquid pool portion 11 moves to a vertically downward position, and the flow path structure tries to keep as horizontal as possible. Therefore, the positional relationship between the liquid pool portion 11 and the gas pool portion 12 can be maintained so that the function of collecting air bubbles can be exerted.

[0093] (Aspects and Effects of the Present Disclosure) As described above, the present disclosure includes the following aspects. Furthermore, according to these aspects, it is possible to suppress the effects of bubbles generated from the liquid in the microchannel device. The effects of each aspect of the present disclosure are as follows. (First aspect) A flow channel structure constituting a part of a microchannel device, The flow path structure includes: an inlet flow path through which a liquid flows; A liquid pool portion connected to the inflow flow path; a gas reservoir portion provided vertically above the liquid reservoir portion; an outflow flow path connected to the liquid pool; A flow path structure comprising: [Effect of the first aspect] When sensing in a system using a microfluidic device, the movement of air bubbles into the sensing area is prevented, reducing problems during measurement. -Reduces the generation of air bubbles that can affect the flow of liquid in microfluidic devices.

[0094] (Second aspect) an inlet valve provided between the inlet flow path and the liquid reservoir; An outflow valve provided between the liquid reservoir and the outflow flow path, The flow path structure described in the first aspect, characterized in that the inlet valve and the outlet valve are adjustment valves capable of controlling the flow of the liquid, and by operating the inlet valve and the outlet valve, air bubbles generated from the liquid are guided to the upper side of the liquid pool portion. [Effect of the second aspect] - Backflow can be prevented by appropriately controlling the microchannels with valves. -Air bubbles can be easily guided to the upper part of the liquid pool. By reducing the kinetic energy of the liquid when it flows out, the secondary generation of bubbles while passing through the flow path can be suppressed.

[0095] (Third aspect) The direction in which the liquid flows is the flow direction, and in a cross-sectional view in a direction perpendicular to the flow direction, The flow path structure according to the first or second aspect, wherein the liquid reservoir portion has a flow path area larger than the inflow flow path and the outflow flow path. (Fourth aspect) The flow channel structure according to any one of the first to third aspects, characterized in that, when the microchannel device is placed on the flow channel, the liquid level in the outlet flow channel is lower than the liquid level in the inlet flow channel. [Effects of the third and fourth aspects] By providing flow paths at different height positions before and after the liquid pool (the flow path in front of the liquid pool (the inlet flow path) is at a higher position than the outlet flow path) and providing space above the liquid pool, it is possible to trap air bubbles using only the structure, without using external forces.

[0096] (Fifth aspect) A partition member having a surface that is provided in the liquid pool and extends in a direction perpendicular to the liquid flow direction, the partition member being configured so that the liquid flows in the direction perpendicular to the liquid flow direction, The partition member, in a cross-sectional view in a direction perpendicular to the flow direction, covering an area including a liquid level height that is a liquid level height reached by the liquid remaining in the liquid pool; The flow path structure according to any one of the first to fourth aspects, wherein the shape of the flow path changes such that the area covering the liquid pool portion narrows as the flow path moves vertically downward from the liquid level height. [Effect of the fifth aspect] -Secondary bubbles are less likely to occur as the liquid passes through the flow path.

[0097] (Sixth aspect) The flow channel structure according to any one of the first to fifth aspects, wherein the gas accumulation portion includes an exhaust mechanism that opens a space of the gas accumulation portion to the outside of the microchannel device. [Effect of the 6th aspect] -Because it is an open system, trapped gas is discharged outside, allowing it to be used for a long time.

[0098] (Seventh aspect) Aspect 10. The flow path structure according to aspect 1, further comprising an absorbing member that absorbs gas in the gas accumulation portion. [Effect of the seventh aspect] The absorbent material (e.g., absorbent sheet) can reliably trap air bubbles inside the device. -Using sheets that absorb VOCs (volatile organic compounds) helps reduce the environmental impact.

[0099] (Eighth aspect) A flow path structure according to any one of the first to seventh aspects, further comprising a gas permeable membrane between the liquid pool and the gas pool. [Effect of the 8th aspect] The gas permeable membrane prevents leakage of liquid sample from the discharge mechanism.

[0100] (Ninth aspect) The flow path structure according to any one of the first to eighth aspects, further comprising a cleaning flow path that introduces a cleaning liquid into the liquid pool. [Effect of the 9th aspect] - It becomes possible to clean the liquid pool area.

[0101] (Tenth aspect) A microchannel device having the channel structure according to any one of the first to ninth aspects. [Effect of the 10th aspect] A microchannel device can be obtained that can suppress the effects of air bubbles generated from the liquid.

[0102] (Eleventh aspect) A wearable device equipped with a microchannel device having a channel structure according to any one of the first to ninth aspects, A wearable device comprising: a holding mechanism that holds the gas pool portion so that it is positioned vertically upward relative to the liquid pool portion. [Effect of the 11th aspect] Even if a flow path is incorporated into a wearable device, rollers can be provided between the wearable device and its flow path to ensure that as much space as possible is provided above, even if the flow path is tilted due to exercise, etc., so that the flow path can be kept as horizontal as possible. [Industrial Applicability]

[0103] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present invention.

[0104] In addition, bubbles often exist in the flow path due to changes in temperature and pressure, but when the flow path is used as a biodevice, CO2 is inevitably emitted due to microbial respiration, etc. In addition, a large amount of CO2 is emitted during alcohol fermentation in brewing using yeast. Microfluidic devices are often used as biodevices rather than to observe physical changes. In such cases, such as in the fields of microbiology and brewing, the ability to predict the presence of large amounts of air bubbles and remove them as much as possible is likely to become increasingly necessary in the future. [Explanation of symbols]

[0105] 1, 1a: flow path structure, 10: inflow flow path, 11: liquid pool, 11a: connection flow path, 12: gas pool, 13: outflow flow path, 14: inflow valve, 15: outflow valve, 21: discharge mechanism, 22: partition member, 22a: upper base, 22b: lower base, 23: cleaning flow path, 24: stopper, 25: gap, 30: holding mechanism, 31: roller portion, 32: support portion, 33: human body, 40: air bubble, 41: air bubble generating portion, 42: flow rate meter, 43: remover, 300: wearable device

Claims

1. A flow channel structure constituting a part of a microchannel device, The flow path structure includes: an inlet flow path through which a liquid flows; A liquid pool connected to the inflow channel; a gas reservoir portion provided vertically above the liquid reservoir portion; an outflow flow path connected to the liquid pool; A flow path structure comprising:

2. an inlet valve provided between the inlet flow path and the liquid reservoir; An outflow valve provided between the liquid reservoir and the outflow flow path, 2. The flow path structure according to claim 1, wherein the inlet valve and the outlet valve are adjustment valves capable of controlling the flow of the liquid, and by operating the inlet valve and the outlet valve, air bubbles generated from the liquid are guided to an upper side of the liquid pool portion.

3. The direction in which the liquid flows is the flow direction, and in a cross-sectional view in a direction perpendicular to the flow direction, The flow path structure according to claim 1 , wherein the liquid pool portion has a flow path area larger than the inflow flow path and the outflow flow path.

4. 2. The flow channel structure according to claim 1, wherein when the microchannel device is placed, a liquid level in the outflow channel is lower than a liquid level in the inflow channel.

5. A partition member having a surface that is provided in the liquid pool and extends in a direction perpendicular to the liquid flow direction, the partition member being configured so that the liquid flows in the direction perpendicular to the liquid flow direction, The partition member, in a cross-sectional view in a direction perpendicular to the flow direction, covering an area including a liquid level height that is a liquid level height reached by the liquid remaining in the liquid pool; 2. The flow path structure according to claim 1, wherein the shape of the flow path changes such that the area covering the liquid pool portion narrows as the flow path moves vertically downward from the liquid level height.

6. The flow channel structure according to claim 1 , wherein the gas accumulation portion includes a discharge mechanism that opens a space of the gas accumulation portion to the outside of the microchannel device.

7. The flow path structure according to claim 1 , further comprising an absorbing member for absorbing gas in the gas accumulation portion.

8. The flow path structure according to claim 1 , further comprising a gas-permeable membrane between the liquid pool and the gas pool.

9. The flow path structure according to claim 5 , further comprising a cleaning flow path for introducing a cleaning liquid into the liquid pool portion.

10. A microchannel device having the channel structure according to claim 1 .

11. A wearable device equipped with a microchannel device having the channel structure according to any one of claims 1 to 9, A wearable device comprising: a holding mechanism that holds the gas pool portion so that it is positioned vertically upward relative to the liquid pool portion.

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