Assay Device

Abstract

[Problem] To provide an assay device with which stable liquid replacement in a microchannel is possible even for a liquid with a relatively small interfacial tension, or even for a microchannel for which the interfacial tension has been weakened by a surface treatment such as blocking. [Solution] The assay device has: an inlet 2; an internal channel 3 in which liquid injected from the inlet 2 flows; and a liquid absorption member 4 absorbing liquid which has passed through the internal channel 3. The internal channel 3 includes: a microchannel 31 having an assay area 31c; and a separation channel 32, which is for separating internal liquid when injection of the liquid is stopped, provided between the microchannel 31 and the liquid absorption member 4. The separation channel 32 has a channel surface change section that causes a change to the surface of the separation channel 32 which the liquid contacts.

Description

[Technical Field]

[0001] The present invention relates to an assay device, and more particularly to an assay device capable of performing an assay using a small amount of liquid. [Background technology]

[0002] One known example of this type of conventional assay device is the assay device described in Patent Document 1. The assay device described in Patent Document 1 includes a microchannel configured to allow a fluid to flow, an absorbent porous medium disposed at an interval from one end of the microchannel located on one end side of the fluid flow direction, a separation space disposed between the one end of the microchannel and the absorbent porous medium, and two side air passages adjacent to the microchannel on both sides in a width direction perpendicular to the flow direction so as to communicate with the microchannel and allowing air to circulate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 045551 Summary of the Invention [Problem to be solved by the invention]

[0004] In the assay device described in Patent Document 1, when a microchannel is filled with a first liquid, a second liquid is injected into the microchannel in an amount that exceeds the amount of the first liquid, thereby replacing the liquid in the microchannel with the second liquid, i.e., liquid exchange within the microchannel is possible.

[0005] However, if the interfacial tension of the liquid is low, the liquid may not be able to stably remain in the microchannel. If the liquid does not stably remain in the microchannel, it becomes difficult for the liquid to maintain a stable shape within the microchannel. As a result, air may get mixed into the microchannel, preventing stable liquid exchange within the microchannel.

[0006] Here, sample liquids (extracts, etc.) used in biochemical tests often contain relatively large amounts of surfactants, and their interfacial tension tends to be low due to the influence of blocking agents used in blocking treatments on the surface of microchannels. Furthermore, processing sample liquids in biochemical tests may require multi-step reactions, such as ELISA (Enzyme-Linked ImmunoSorbent Assay). For these reasons, stable liquid exchange within microchannels is required, especially when sample liquids used in biochemical tests are used.

[0007] This demand is not limited to cases where sample liquids are used in biochemical tests, but is common to cases where liquids with relatively low interfacial tension are used.

[0008] Therefore, an object of the present invention is to provide an assay device that enables stable liquid exchange within a microchannel, even for liquids with relatively low interfacial tension or microchannels where the interfacial tension has been weakened by surface treatment such as blocking. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided an assay device having an injection port, an internal flow path through which a liquid injected from the injection port flows, and a liquid absorbent material that absorbs the liquid that has passed through the internal flow path, wherein the internal flow path includes a microflow path having an assay region, and a separation flow path that is provided between the microflow path and the liquid absorbent material and that separates the liquid in the internal flow path into a portion that is retained in the microflow path and a portion that is absorbed by the liquid absorbent material when the injection of the liquid is stopped, and the separation flow path has a flow path surface changing portion that changes the surface of the separation flow path that comes into contact with the liquid. The flow path surface change portion has a step structure that creates a step in the separation flow path, and the step structure of the flow path surface change portion is formed from a material that is impermeable to liquid and includes an obstacle-forming member that is installed at an upstream end of the liquid absorbent material in the flow direction of the liquid. . According to another aspect of the present invention, there is provided an assay device having an injection port, an internal flow path through which a liquid injected from the injection port flows, and a liquid absorbent material that absorbs the liquid that has passed through the internal flow path, wherein the internal flow path includes a microflow path having an assay region, and a separation flow path that is provided between the microflow path and the liquid absorbent material and that separates the liquid in the internal flow path into a portion that is retained in the microflow path and a portion that is absorbed by the liquid absorbent material when the injection of the liquid is stopped, and the separation flow path has a flow path surface changing portion that changes the surface of the separation flow path that comes into contact with the liquid, and the flow path surface changing portion has a step structure that creates a step in the separation flow path, and The device comprises a lower flow path forming member having a lower wall portion that forms a lower wall, an intermediate member joined to the upper surface of the lower flow path forming member, and an upper flow path forming member joined to the upper surface of the intermediate member and having an upper wall portion that forms the upper wall of the internal flow path, wherein the internal flow path is formed by the upper flow path forming member, the lower flow path forming member, and the intermediate member that functions as a spacer between the upper flow path forming member and the lower flow path forming member, and the step structure of the flow path surface change portion is a protrusion that is formed on at least one of the upper wall portion and the lower wall portion and protrudes into the inside of the separation flow path at a position corresponding to the upstream end of the liquid absorbent in the flow direction of the liquid. According to another aspect of the present invention, there is provided an assay device having an injection port, an internal flow path through which a liquid injected from the injection port flows, and a liquid absorbent material that absorbs the liquid that has passed through the internal flow path, wherein the internal flow path includes a microflow path having an assay region, and a separation flow path that is provided between the microflow path and the liquid absorbent material and that separates the liquid in the internal flow path into a portion that is retained in the microflow path and a portion that is absorbed by the liquid absorbent material when the injection of the liquid is stopped, and the separation flow path has a flow path surface changing portion that changes the surface of the separation flow path that comes into contact with the liquid, and the flow path surface changing portion has a step structure that creates a step in the separation flow path. The liquid absorbent material includes a lower flow path forming member having a lower wall portion that forms the lower wall of the internal flow path, an intermediate member joined to the upper surface of the lower flow path forming member, and an upper flow path forming member joined to the upper surface of the intermediate member and having an upper wall portion that forms the upper wall of the internal flow path, wherein the internal flow path is formed by the upper flow path forming member, the lower flow path forming member, and the intermediate member that functions as a spacer between the upper flow path forming member and the lower flow path forming member, and the step structure of the flow path surface change portion is a groove portion formed in at least one of the upper wall portion and the lower wall portion at a position corresponding to the upstream end of the liquid absorbent material in the flow direction of the liquid. According to another aspect of the present invention, there is provided an assay device having an injection port, an internal flow path through which a liquid injected from the injection port flows, and a liquid absorbent material that absorbs the liquid that has passed through the internal flow path, wherein the internal flow path includes a microflow path having an assay region, and a separation flow path that is provided between the microflow path and the liquid absorbent material and that separates the liquid in the internal flow path into a portion that is retained in the microflow path and a portion that is absorbed by the liquid absorbent material when the injection of the liquid is stopped, and the separation flow path has a flow path surface changing part that changes the surface of the separation flow path that comes into contact with the liquid, and a lower flow path forming member on which a lower wall part that constitutes the lower wall of the internal flow path is formed, and a lower flow path forming member that forms the lower wall of the lower flow path The liquid flow path forming member includes an intermediate member joined to the upper surface of a forming member, and an upper flow path forming member joined to the upper surface of the intermediate member and having an upper wall portion that forms the upper wall of the internal flow path, wherein the internal flow path is formed by the upper flow path forming member, the lower flow path forming member, and the intermediate member that functions as a spacer between the upper flow path forming member and the lower flow path forming member, and the lower flow path forming member is a member formed by joining a first member that is positioned upstream of the upstream end of the liquid absorbent in the flow direction of the liquid, and a second member that is positioned downstream of the upstream end of the liquid absorbent, and the flow path surface changing portion is the joint between the first member and the second member. [Effects of the Invention]

[0010] According to the present invention, an assay device can be provided that enables stable liquid exchange within a microchannel, even for liquids with relatively low interfacial tension or microchannels where the interfacial tension has been weakened by surface treatment such as blocking. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of the assay device according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the assay device according to the first embodiment. [Figure 3] FIG. 3 is an exploded perspective view of the assay device according to the first embodiment. [Figure 4] 4A to 4C are views showing the upper flow path forming member, where FIG. 4A is a top view of the upper flow path forming member, FIG. 4B is a side view of the upper flow path forming member, and FIG. 4C is a bottom view of the upper flow path forming member. [Figure 5] 5A to 5D are diagrams showing a lower flow path forming member, in which FIG. 5A is a top view of the lower flow path forming member, FIG. 5B is a side view of the lower flow path forming member, FIG. 5C is a bottom view of the lower flow path forming member, and FIG. 5D is a cross-sectional view taken along line AA in FIG. 5A. [Figure 6]6A and 6B are views showing an intermediate member disposed between an upper flow path forming member and a lower flow path forming member, where FIG. 6A is a top view of the intermediate member and FIG. 6B is a side view of the intermediate member. [Figure 7] 7A and 7B are diagrams for explaining the internal flow path and the internal ventilation space, with FIG. 7A mainly showing the upper part of the internal flow path and FIG. 7B mainly showing the lower part of the internal flow path. [Figure 8] 8A to 8D are diagrams for explaining the movement of the first liquid injected into the assay device, and are diagrams that schematically show the internal flow paths and the like when the assay device is viewed from above. [Figure 9] Figures 9A to 9D are diagrams for explaining the movement of the first liquid and the second liquid when the injection of the first liquid into the assay device is stopped and then the second liquid is injected, and are diagrams that schematically show the internal flow paths and the like when the assay device is viewed from above. [Figure 10] 10A to 10F are schematic cross-sectional views of the boundary region between the separation channel and the liquid absorbent material. [Figure 11] FIG. 11 is a perspective view of the assay device according to the second embodiment. [Figure 12] FIG. 12 is an exploded perspective view of the assay device according to the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view of the assay device according to the third embodiment. [Figure 14] FIG. 14 is an exploded perspective view of the assay device according to the third embodiment. [Figure 15] FIG. 15 is an exploded perspective view of the electrochemical assay device according to the fourth embodiment. [Figure 16] 16A and 16B are diagrams showing a structure (including a liquid absorbent material) in which an upper flow path forming member, a lower flow path forming member, and an intermediate member are stacked and integrated, where FIG. 16A is an oblique view of the structure, and FIG. 16B is a cross-sectional view taken along line BB of FIG. 16A. [Figure 17] FIG. 17 is a schematic cross-sectional view of the boundary region between the separation channel and the liquid absorbent material in the first modification. [Figure 18]FIG. 18 is a schematic cross-sectional view of the boundary region between the separation channel and the liquid absorbent material in the second modification. [Figure 19] FIG. 19 is a schematic cross-sectional view of the boundary region between the separation channel and the liquid absorbent material in the third modification. DETAILED DESCRIPTION OF THE INVENTION

[0012] An assay device according to an embodiment of the present invention will now be described.

[0013] The assay device according to the embodiment is a device capable of performing an assay using a minute amount of liquid. The liquid that can be used in the assay device according to the embodiment is not particularly limited as long as it can flow through a flow path (internal flow path) provided in the assay device. Such a liquid is typically an aqueous solution. Furthermore, the liquid that can be used in the assay device according to the embodiment includes not only chemically pure liquids but also liquids in which gases, other liquids, or solids are dissolved, dispersed, or suspended.

[0014] For example, biologically derived liquids may be used. When biologically derived liquids are used, the assay device can measure diagnostically useful analytes in the liquid for applications such as pregnancy tests, urine tests, stool tests, adult disease tests, allergy tests, infectious disease tests, drug tests, and cancer tests. Food suspensions, drinking water, river water, and soil suspensions may also be used. When these are used, the assay device can measure pathogens in food or drinking water, or contaminants in river water or soil.

[0015] As used herein, the term "analyte" refers to a compound or composition that is detected or measured primarily using a liquid. Examples of "analyte" include sugars (e.g., glucose), cells, proteins or peptides (e.g., serum proteins, hormones, enzymes, immunomodulators, lymphokines, monokines, cytokines, glycoproteins, vaccine antigens, antibodies, growth factors), fats, amino acids, nucleic acids, steroids, vitamins, pathogens or their antigens, natural or synthetic chemicals, pollutants, therapeutic or illicit drugs, or metabolites or antibodies of these substances.

[0016] In addition, in this specification, the term "microchannel" refers to a channel within an assay device that enables detection or measurement of a sample using a minute amount of liquid on the order of μl (microliter), i.e., a minute amount of liquid of 1 μl or more but less than 1000 μl.

[0017] [First embodiment] 1 to 3 show an assay device 1 according to a first embodiment. Fig. 1 is a perspective view of the assay device 1, Fig. 2 is a cross-sectional view of the assay device 1, and Fig. 3 is an exploded perspective view of the assay device 1.

[0018] First, the basic configuration of the assay device 1 will be described.

[0019] The assay device 1 is formed into a roughly rectangular parallelepiped overall, and has an inlet 2 through which a liquid is injected (mainly by drop injection) on one side (the right side in FIG. 2) in the longitudinal direction L. The inlet 2 is formed into a circle and opens on the top surface of the assay device 1.

[0020] The assay device 1 also has an internal flow path 3 through which liquid injected from the inlet 2 flows, and a first liquid absorbent 4 that absorbs the liquid that has passed through the internal flow path 3. The internal flow path 3 extends in the longitudinal direction L inside the assay device 1. The first liquid absorbent 4 is made of a flexible porous material that can absorb liquid, and is contained in a storage space 5 provided on the other side of the longitudinal direction L within the assay device 1 (the left side in Figure 2). In other words, the longitudinal direction L is also the direction in which the liquid flows within the assay device 1. In this case, the side of the longitudinal direction L where the inlet 2 is located is the upstream side, and the other side of the longitudinal direction L where the first liquid absorbent 4 is located is the downstream side.

[0021] In this embodiment, the first liquid absorbent 4 is composed of an upper absorbent 4a and a lower absorbent 4b. However, this is not limiting, and the first liquid absorbent 4 may be composed of a single absorbent material.

[0022] In this embodiment, the internal flow path 3 has an upper wall and a lower wall, as is clear from Fig. 2. Furthermore, in this embodiment, the internal flow path 3 is defined by the upper wall and the lower wall and does not have a side wall. The internal flow path 3 also includes a microflow path 31 and a separation flow path 32.

[0023] The microchannel 31 constitutes the upstream channel of the internal channel 3, i.e., the channel on the side closer to the injection port 2. The base end (upstream end) 31a of the microchannel 31 is located near the injection port 2, preferably below the injection port 2 in the height direction H, more specifically directly below the injection port 2. The liquid injected from the injection port 2 flows into the base end 31a of the microchannel 31 and flows from the base end 31a to the downstream side of the microchannel 31. The microchannel 31 extends approximately horizontally from the base end 31a toward the other side in the longitudinal direction L, and the tip end (downstream end) 31b is located approximately in the center in the longitudinal direction L.

[0024] An assay region 31c is provided in the middle of the microchannel 31, i.e., between the base end 31a and the tip end 31b. One or more assay reagents are disposed in the assay region 31c. The assay reagent is any substance that produces a detectable result by reacting with a liquid or a sample contained therein, and may be, for example, an antibody or an antigen. The detectable result is preferably visible to the naked eye of an observer, but is not limited thereto. The detectable result may also be visible to the observer using a predetermined device. The detectable result includes color development, absorbance, luminescence, fluorescence, etc. When performing an assay using an electrochemical method, the detectable result is an electrochemical signal, and the assay reagent preferably includes an electrochemiluminescent label and a reducing agent. An example of the configuration of an assay device for performing an assay using an electrochemical method will be described in detail in the fourth embodiment.

[0025] In this embodiment, the first assay reagent 6a and the second assay reagent 6b are arranged in the assay region 31c, spaced apart from each other in the longitudinal direction L. Specifically, in this embodiment, the first assay reagent 6a and the second assay reagent 6b are fixed to either the lower wall or the upper wall of the microchannel 31, or to both the lower wall and the upper wall. However, this is not limitative. The first assay reagent 6a and / or the second assay reagent 6b may be supported on a porous material that allows liquid to pass through, and the porous material (support) may be placed in the assay region 31c.

[0026] The separation channel 32 constitutes a downstream channel of the internal channel 3, i.e., a channel on the side closer to the first liquid absorbent material 4. One end (upstream end) of the separation channel 32 is connected to the tip end (downstream end) 31b of the microchannel 31. The separation channel 32 extends from the one end toward the other side in the longitudinal direction L, and the other end (downstream end) is in contact with the first liquid absorbent material 4.

[0027] That is, in this embodiment, the first liquid absorbent 4 is provided at a distance from the tip portion (downstream end) 31b of the microchannel 31 in the longitudinal direction L, and the separation channel 32 is provided between (the tip portion 31b of) the microchannel 31 and the first liquid absorbent 4. As will be described later, the separation channel 32 is configured to separate the liquid in the internal channel 3 when the injection of liquid into the inlet 2 is stopped, in other words, when the supply of liquid to the internal channel 3 is stopped. Specifically, when the injection of liquid into the inlet 2 is stopped, the liquid in the internal channel 3 is separated in the separation channel 32, and part of the separated liquid is absorbed by the first liquid absorbent 4, and the remainder remains (is retained) in the microchannel 31.

[0028] The separation channel 32 is further provided with a channel surface change portion that changes the surface of the separation channel 32 that comes into contact with the liquid, in order to promote separation of the liquid on the upstream side of the first liquid absorbent 4. The channel surface change portion will be described later.

[0029] Furthermore, an internal ventilation space 7 is provided inside the assay device 1, which, in top view, surrounds the microchannel 31 except for the tip 31b to which the one end (upstream end) of the separation channel 32 is connected and communicates with the outside. As described above, in this embodiment, the internal channel 3 has no sidewalls. Therefore, the internal ventilation space 7 also communicates with the microchannel 31. In this embodiment, the internal ventilation space 7 includes a pair of side spaces 7a, 7a (one of which is shown by a dashed line in FIG. 2 ) adjacent to the microchannel 31 on both sides in the short direction (hereinafter referred to as the "width direction") W and communicating with the microchannel 31, and a connecting space 7b extending along the outer edge of the injection port 2 and connecting the pair of side spaces 7a, 7a. The communication between the internal ventilation space 7 and the outside will be described later.

[0030] 2, in this embodiment, the upper and lower walls of the microchannel 31 extend substantially horizontally, and the height of the microchannel 31, i.e., the distance between the upper and lower walls of the microchannel 31 in the height direction H, is constant (it does not need to be strictly constant, as long as it is approximately constant; the same applies below). The height of the microchannel 31 is determined so as to generate interfacial tension of the liquid that prevents leakage of the liquid into the internal ventilation space 7 (particularly the side space) when the liquid flows through the microchannel 31. On the other hand, the upper wall of the separation channel 32 is formed by directly extending the upper wall of the microchannel 31 and extends substantially horizontally, but the lower wall of the separation channel 32 is inclined downward so that the height position decreases as it moves away from (the tip 31b of) the microchannel 31, i.e., as it approaches the first liquid absorbent 4.

[0031] Here, although not particularly limited, the height of the microchannel 31 may be set in the range of, for example, 1 μm to 1 mm, the width (dimension in the width direction W) of the microchannel 31 may be set in the range of, for example, 100 μm to 1 cm, and the length (dimension in the longitudinal direction L) of the microchannel 31 may be set in the range of, for example, 10 μm to 10 cm.

[0032] Furthermore, particularly when the liquid is a sample liquid for biochemical testing, it is preferable that the surfaces of the internal channel 3 (microchannel 31 and separation channel 32) that come into contact with the liquid be subjected to a blocking treatment or plasma treatment to prevent nonspecific adsorption of biological substances, antigens, antibodies, etc. Blocking agents used in blocking treatment include commercially available blocking agents, bovine serum albumin, casein, skim milk, gelatin, surfactants, polyvinyl alcohol, globulin, serum (e.g., fetal bovine serum or normal rabbit serum), ethanol, MPC polymer, etc. Commercially available blocking agents include, but are not limited to, Immunoblock, Block Ace, Pierce Blocking Buffer, StartingBlock, StabilGuard, StabilBrock, StabilCoat, and ChonBlock.

[0033] The internal flow path 3 and the internal ventilation space 7 will be further described.

[0034] In this embodiment, the internal flow path 3 and the internal ventilation space 7 are formed by stacking an upper flow path forming member 11, a lower flow path forming member 12, and an intermediate member 13 that functions as a spacer between them. Below, the upper flow path forming member 11, the lower flow path forming member 12, and the intermediate member 13 will be described in order.

[0035] 4A to 4C show the upper flow path forming member 11. Fig. 4A is a top view of the upper flow path forming member 11, Fig. 4B is a side view of the upper flow path forming member 11, and Fig. 4C is a bottom view of the upper flow path forming member 11.

[0036] In this embodiment, the upper flow path forming member 11 is made of a transparent synthetic resin and is formed to have a certain degree of flexibility. Preferably, the upper flow path forming member 11 is made of a molded product of a transparent synthetic resin. Examples of such synthetic resins include, but are not limited to, PS resin (polystyrene), PMMA (acrylic resin), PC (polycarbonate), COP (cycloolefin polymer), COC (cycloolefin copolymer), ABS resin, AS resin, and silicone resin. In addition, the contact angle of the surface of the upper flow path forming member 11 with respect to water is preferably 90 degrees or less.

[0037] 4A to 4C, the upper flow path forming member 11 has an outer shape that is rectangular when viewed from above. In addition, the upper flow path forming member 11 has a predetermined range on one side in the longitudinal direction L that is larger in the height direction H than other portions, in other words, is formed to have a thicker wall thickness. Hereinafter, the portion on one side in the longitudinal direction L that is larger in the height direction H (thicker wall thickness) will be referred to as the thick portion 11a, and the remaining portion that is thinner in thickness than the thick portion 11a will be referred to as the thin portion 11b.

[0038] An injection port 2 is formed in the thick portion 11a of the upper flow path forming member 11 so as to penetrate the thick portion 11a in the height direction H. That is, the injection port 2 opens on the upper surface of the thick portion 11a of the upper flow path forming member 11. The injection port 2 is formed in the center in the width direction W and at a position close to the thin portion 11b.

[0039] An upper wall portion 111 that, together with a part of the thick portion 11a (the portion surrounding the injection port 2), constitutes the upper wall of the internal flow path 3, and a pair of first openings 112, 112 that sandwich the upper wall portion 111 in the width direction W, are formed in the thin portion 11b of the upper flow path forming member 11. The upper wall portion 111 extends from the vicinity of the injection port 2 toward the other side in the longitudinal direction L. The pair of first openings 112, 112 are formed symmetrically, extend in the longitudinal direction L along the side edges of the upper wall portion 111, and penetrate the thin portion 11b of the upper flow path forming member 11 in the height direction. In other words, a pair of first openings 112, 112 spaced apart in the width direction W and penetrating in the height direction H are formed in the thin-walled portion 11b of the upper flow path forming member 11, and the area between the pair of first openings 112, 112 in the thin-walled portion 11b of the upper flow path forming member 11 constitutes the upper wall portion 111.

[0040] In this embodiment, the upper wall portion 111 has, in order from the one side in the longitudinal direction L, i.e., the side closer to the injection port 2, an upper tapered portion 111a, a first upper straight portion 111b, an upper narrow portion 111c, and a second upper straight portion 111d.

[0041] Upper tapered portion 111a extends from the vicinity of injection port 2 toward the other side in longitudinal direction L and is formed so that its width gradually narrows (the dimension in width direction W gradually decreases) with increasing distance from injection port 2.

[0042] The first upper straight portion 111b has the same width as the tip of the upper tapered portion 111a and extends linearly from the tip of the upper tapered portion 111a toward the other side in the longitudinal direction L. The width of the first upper straight portion 111b is constant. The tip of the first upper straight portion 111b is located approximately in the center in the longitudinal direction L.

[0043] The upper narrow width portion 111c is a portion where the width of the upper wall portion 111 narrows. In this embodiment, the second upper straight portion 111d is formed to be narrower than the first upper straight portion 111b. The upper narrow width portion 111c is formed in a tapered shape in which its width gradually narrows from the width of the first upper straight portion 111b to the width of the second upper straight portion 111d, connecting the first upper straight portion 111b and the second upper straight portion 111d. However, this is not limited to this. The upper narrow width portion 111c may be any portion where the width of the upper wall portion 111 narrows, and may be formed in a stepped shape or a multiple-tapered shape, for example.

[0044] As described above, the second upper straight portion 111d is formed to be narrower than the first upper straight portion 111b, and extends linearly from the upper narrow portion 111c toward the other side in the longitudinal direction L. The width of the second upper straight portion 111d is constant.

[0045] Furthermore, rectangular through-holes 113, 113 that are long in the width direction W are formed in the thin-walled portion 11b of the upper flow path forming member 11. The through-holes 113, 113 are provided spaced apart from each other in the longitudinal direction L at positions spaced apart from the tip end of (the second upper straight portion 111d of) the upper wall portion 111 on the other side in the longitudinal direction L.

[0046] 5A to 5D show the lower flow path forming member 12. Fig. 5A is a top view of the lower flow path forming member 12, Fig. 5B is a side view of the lower flow path forming member 12, Fig. 5C is a bottom view of the lower flow path forming member 12, and Fig. 5D is a cross-sectional view taken along line AA in Fig. 5A.

[0047] In this embodiment, the lower flow path forming member 12, like the upper flow path forming member 11, is made of a transparent synthetic resin and is formed to have a certain degree of flexibility. The lower flow path forming member 12 is preferably formed as a molded product of a transparent synthetic resin. The lower flow path forming member 12 is preferably formed of the same synthetic resin as the upper flow path forming member 11, but may be formed of a different synthetic resin. The contact angle of the surface of the lower flow path forming member 12 with respect to water is preferably 90 degrees or less.

[0048] 5A to 5C, the lower flow-path forming member 12 is formed to have a rectangular outer shape in top view so as to correspond to the upper flow-path forming member 11. Furthermore, the lower flow-path forming member 12 has a lower wall portion 121 that constitutes the lower wall of the internal flow path 3, formed so as to correspond to the injection port 2 and upper wall portion 111 formed in the upper flow-path forming member 11. In other words, the lower wall portion 121 is formed so as to be located below the injection port 2 and upper wall portion 111 of the upper flow-path forming member 11 when the upper flow-path forming member 11, the lower flow-path forming member 12, and the intermediate member 13 are stacked. The lower wall portion 121 extends from one side to the other side in the longitudinal direction L, similar to the upper wall portion 111.

[0049] In this embodiment, the lower wall portion 121 has, in order from one side in the longitudinal direction L, a semicircular portion 121a, a lower tapered portion 121b, a first lower straight portion 121c, a lower narrow portion 121d, and a second lower straight portion 121e.

[0050] The semicircular portion 121a is a portion corresponding to the injection port 2 of the upper flow path forming member 11. The semicircular portion 121a is concentric with the injection port 2 of the upper flow path forming member 11 indicated by the two-dot chain line in FIG. 5A and has a diameter larger than that of the injection port 2.

[0051] The lower tapered portion 121b is a portion corresponding to the upper tapered portion 111a of the upper flow path forming member 11. The lower tapered portion 121b extends from the semicircular portion 121a toward the other side in the longitudinal direction L and is formed so that its width gradually narrows with increasing distance from the semicircular portion 121a. The gradient of the lower tapered portion 121b is set to be the same as the gradient of the upper tapered portion 111a.

[0052] The first lower straight portion 121c is a portion corresponding to the first upper straight portion 111b of the upper flow path forming member 11. The first lower straight portion 121c has the same width as the tip end of the lower tapered portion 121b, and extends linearly from the tip end of the lower tapered portion 121b toward the other side in the longitudinal direction L. The first lower straight portion 121c has the same width as the first upper straight portion 111b.

[0053] Here, in this embodiment, a substantially U-shaped groove portion 122 with its open portion facing the other side is formed on the upper surface of the lower flow path forming member 12 on the one side of the center in the longitudinal direction L, and the inner part of the groove portion 122 in the lower flow path forming member 12 constitutes a semicircular portion 121a, a lower tapered portion 121b, and a first lower straight portion 121c.

[0054] The lower narrow width portion 121d is a portion corresponding to the upper narrow width portion 111c of the upper flow path forming member 11, and is a portion where the width of the lower wall portion 121 narrows. In this embodiment, the second lower straight portion 121e is narrower than the first lower straight portion 121c and is formed to have the same width as the second upper straight portion 111d of the upper flow path forming member 11. The lower narrow width portion 121d is formed in a tapered shape in which its width gradually narrows from the width of the first lower straight portion 121c to the width of the second lower straight portion 121e, thereby connecting the first lower straight portion 121c and the second lower straight portion 121e. Note that if the upper narrow width portion 111c is formed in a stepped shape or a tapered shape, for example, the lower narrow width portion 121d is also formed in a stepped shape or a tapered shape accordingly.

[0055] The second lower straight portion 121e is a portion corresponding to the second upper straight portion 111d of the upper flow path forming member 11. As described above, the second lower straight portion 121e is formed to be narrower than the first lower straight portion 121c (having the same width as the second upper straight portion 111d), and extends linearly from the lower narrow portion 121d toward the other side in the longitudinal direction L.

[0056] In this embodiment, a generally U-shaped cutout hole 123 with its open portion facing the one side is formed on the other side of the center of the lower flow-path forming member 12 in the longitudinal direction L, and the portion inside the cutout hole 123 in the lower flow-path forming member 12 forms the lower narrow portion 121d and the second lower straight portion 121e. The upper surfaces of the lower narrow portion 121d and the second lower straight portion 121e are inclined so that their height positions gradually decrease with increasing distance from the tip end of the first lower straight portion 121c. A portion of the cutout hole 123 on the other side in the longitudinal direction L forms the storage space 5 in which the first liquid absorbent 4 is stored.

[0057] A recess 124 is formed on the lower surface of the lower flow path forming member 12 on the one side of the center in the longitudinal direction L. The recess 124 is large enough to contain at least most of the lower tapered portion 121b of the lower wall portion 121 in a top view. A back plate 15, which will be described later, is housed in this recess 124.

[0058] Furthermore, a plurality of (six in this case) pins 125 are provided at intervals from one another to protrude from the peripheral edge of the lower surface of the lower flow path forming member 12. Although six pins 125 are provided in this case, the number of pins 125 can be set arbitrarily.

[0059] 6A and 6B show the intermediate member 13. Fig. 6A is a top view of the intermediate member 13, and Fig. 6B is a side view of the intermediate member 13.

[0060] 6A and 6B, the intermediate member 13 has a rectangular outer shape in top view so as to correspond to the upper flow path forming member 11 and the lower flow path forming member 12. The intermediate member 13 has a small dimension in the height direction H (i.e., thickness) and has a second opening 13a penetrating through in the height direction H on the inside. The dimension (thickness) of the intermediate member 13 in the height direction H is set according to the required height of the microflow path 31. The second opening 13a has a size sufficient to accommodate the injection port 2, the upper wall portion 111, the pair of first openings 112, 112, and the through-holes 113, 113 formed in the upper flow path forming member 11, in top view.

[0061] The upper and lower surfaces of the intermediate member 13 are formed as adhesive surfaces. As an example, the intermediate member 13 can be formed by arranging double-sided adhesive sheets on the upper and lower surfaces of a sheet material. In this case, for example, by appropriately selecting a sheet material having an arbitrary thickness, the dimension of the intermediate member 13 in the height direction H, and therefore the height of the microchannel 31, can be freely changed. Furthermore, the shape and type of the intermediate member 13 can be freely changed as long as the liquid does not penetrate at least into the portion (spacer portion) of the intermediate member 13 that functions as a spacer.

[0062] Then, the lower surface of the upper flow path-forming member 11 is joined to the upper surface of the intermediate member 13, and the upper surface of the lower flow path-forming member 12 is joined to the lower surface of the intermediate member 13, whereby the upper flow path-forming member 11, the lower flow path-forming member 12, and the intermediate member 13 are stacked and integrated. This forms the internal flow path 3 and the internal ventilation space 7. Here, in actual assembly, before the upper flow path-forming member 11, the lower flow path-forming member 12, and the intermediate member 13 are integrated, the lower absorbent 4b of the first liquid absorbent 4 is accommodated in a predetermined position (accommodation space 5) in the cutout hole 123 of the lower flow path-forming member 12, and further the upper absorbent 4a is placed on the lower absorbent 4b.

[0063] The upper absorbent material 4a is at least partially provided with the flow path surface change portion described above. Specifically, obstacle-forming members 410a and 410b, which function as flow path surface change portions that bring about changes in the surface of the separation flow path 32, are provided on the upper and lower surfaces of the upper absorbent material 4a, respectively. As a result, the upper absorbent material 4a with the obstacle-forming members 410a and 410b provided thereon is placed on top of the lower absorbent material 4b housed in the housing space 5.

[0064] 7A and 7B are diagrams for explaining the internal flow path 3 and the internal ventilation space 7. Fig. 7A is a view of the upper flow path forming member 11 and the intermediate member 13 seen from the lower flow path forming member 12 side, and mainly shows the upper part of the internal flow path 3. Fig. 7B is a view of the lower flow path forming member 12 seen from the intermediate member 13 side, and mainly shows the lower part of the internal flow path 3. Note that the two-dot chain line in the figure indicates the first liquid absorbent 4 (upper absorbent 4a, lower absorbent 4b), and the obstacle-forming members 410a, 410b arranged on the upper absorbent 4a are shown by hatching.

[0065] In this embodiment, the upper tapered portion 111a and the first upper straight portion 111b of the upper wall portion 111 of the upper flow path forming member 11 form the upper wall of the microflow path 31 in the internal flow path 3, and the semicircular portion 121a, the lower tapered portion 121b and the first lower straight portion 121c of the lower wall portion 121 of the lower flow path forming member 12 form the lower wall of the microflow path 31 in the internal flow path 3. Furthermore, the upper narrow portion 111c and the second upper straight portion 111d of the upper wall portion 111 of the upper flow path forming member 11 form the upper wall of the separation flow path 32 in the internal flow path 3, and the lower narrow portion 121d and the second lower straight portion 121e of the lower wall portion 121 of the lower flow path forming member 12 form the lower wall of the separation flow path 32 in the internal flow path 3.

[0066] That is, the microchannel 31 is formed as a channel having a tapered channel section 311 that extends from the vicinity of the injection port 2 toward the separation channel 32 and whose channel width gradually narrows with increasing distance from the injection port 2, and a first straight channel section 312 that extends from the tip of the tapered channel section 311 to the separation channel 32 and has a constant channel width. Note that, although not particularly limited, the channel width near the inlet of the microchannel 31 (i.e., near the injection port 2) may be, for example, 2 mm or more and 10 mm or less, and the channel width near the outlet of the microchannel 31 (i.e., near the separation channel 32) may be, for example, 1 mm or more and 6 mm or less.

[0067] The separation channel 32 is formed as a channel extending from the microchannel 31 toward the first liquid absorbent 4, and is formed as a channel having a narrow width portion 321 where the channel width narrows, and a second straight channel portion 322 that extends from the narrow width portion 321 to the first liquid absorbent 4 and has a channel width narrower than the first straight channel portion 312. The narrow width portion 321 is formed in a tapered shape such that the channel width gradually narrows from the channel width of the first straight channel portion 312 of the microchannel 31 to the channel width of the second straight channel portion 322. The lower wall of the separation channel 32 is inclined downward so that the height position decreases as it approaches the first liquid absorbent 4. Although not particularly limited, the channel width near the outlet of the narrow width portion 321 can be, for example, 0.5 mm or more and 5 mm or less.

[0068] Obstacle-forming members 410a and 410b are arranged in the second straight flow path portion 322 of the separation flow path 32. Specifically, the obstacle-forming members 410a and 410b are arranged at positions corresponding to the upstream end of the first liquid absorbent 4 in the liquid flow direction.

[0069] Furthermore, the internal ventilation space 7 (side spaces 7a, 7a and connecting space 7b) is formed by a substantially U-shaped recessed groove portion 122 and the space above it, which are formed on the upper surface of the lower flow path forming member 12 on the one side of the center in the longitudinal direction L. The pair of first openings 112, 112 formed in the upper flow path forming member 11 are located above the side spaces 7a, 7a of the internal ventilation space 7 and communicate with the side spaces 7a, 7a.

[0070] Here, the obstacle-forming members 410a, 410b will be described. As described above, the obstacle-forming members 410a, 410b are members provided to promote separation of the liquid on the upstream side of the first liquid absorbent 4, and are configured to function as flow path surface change sections that bring about changes in the surface of the separation flow path 32 that comes into contact with the liquid. In this embodiment, the obstacle-forming members 410a, 410b are provided on the first liquid absorbent 4, but because they are members that promote separation of the liquid, they can also be said to be part of the separation flow path 32.

[0071] By providing the obstacle-forming members 410a and 410b to the first liquid absorbent 4, a step structure is essentially formed that protrudes from the upper passage-forming member 11 and the lower passage-forming member 12 toward the inside of the separation flow channel 32. That is, by providing the obstacle-forming members 410a and 410b, the surface of the separation flow channel 32 that comes into contact with the liquid changes, that is, the dimension in the height direction H of the separation flow channel 32 changes locally. The obstacle-forming member 410a is provided on the upper surface of one side, i.e., the upstream end, of the upper absorbent 4a of the first liquid absorbent 4, and the obstacle-forming member 410b is provided on the lower surface of one side, i.e., the upstream end, of the upper absorbent 4a.

[0072] As an example, the obstacle-forming members 410a, 410b can be formed by placing double-sided adhesive sheets or the like on the upper and lower surfaces of a sheet material, respectively. By appropriately selecting a sheet material with a desired thickness, the height direction H of the obstacle-forming members 410a, 410b can be set to a desired dimension. The sheet material is made of a hydrophobic material that is impermeable to liquids, such as, but not limited to, PET (polyethylene terephthalate) or glass. The obstacle-forming members 410a, 410b are attached to the upper and lower surfaces of the upper absorbent material 4a, respectively, via double-sided adhesive sheets.

[0073] The upper absorbent material 4a is formed from a flexible porous material such as cotton, and therefore obstacle-forming members 410a, 410b are respectively placed on the upper and lower surfaces of the upper absorbent material 4a, and when the upper flow path forming member 11, the lower flow path forming member 12 and the intermediate member 13 are integrated, the obstacle-forming members 410a, 410b are positioned so as to sink into the upper absorbent material 4a.

[0074] Here, the shape of the obstacle-forming members 410a, 410b is not particularly limited, but can be, for example, a rectangular parallelepiped. The thickness (dimension in the height direction H) of the obstacle-forming members 410a, 410b is set depending on the height of the separation channel 32 and the composition of the liquid injected into the assay device 1 to promote liquid separation. Although not particularly limited, the thickness of each of the obstacle-forming members 410a, 410b can be set, for example, in the range of 1 μm to 1000 μm. The width (dimension in the width direction W) of the obstacle-forming members 410a, 410b is preferably equal to or greater than the channel width, but is not particularly limited. Furthermore, the length (dimension in the longitudinal direction L) of the obstacle-forming members 410a, 410b is set depending on, for example, the dimensions of the first liquid absorbent 4, the dimensions of the separation channel 32, and the composition of the liquid injected into the assay device 1 to promote liquid separation. Although not particularly limited, the lengths of the obstacle forming members 410a and 410b can be set in the range of, for example, 0.1 mm to 100 mm.

[0075] In this embodiment, the obstacle-forming member 410a is provided on the upper surface of the upper absorbent material 4a, and the obstacle-forming member 410b is provided on the lower surface of the upper absorbent material 4a, but it is also possible to provide only one of them. Whether to provide both obstacle-forming members 410a and 410b or only one of the obstacle-forming members 410a and 410b can be determined appropriately depending on the thickness of the obstacle-forming members, the height of the separation channel 32, the composition of the liquid injected into the assay device 1, and other factors. Because the upper absorbent material 4a is made of a flexible porous material, even if the number and dimensions of the obstacle-forming members are changed depending on the composition of the liquid, no additional materials or processing are required to provide the obstacle-forming members.

[0076] Next, other configurations of the assay device 1 will be described with reference to FIGS.

[0077] In addition to the above-mentioned first liquid absorbent 4 (upper absorbent 4a and lower absorbent 4b), upper flow path forming member 11, lower flow path forming member 12, and intermediate member 13, the assay device 1 further has an upper cover 14, a back panel 15, a second liquid absorbent 16, and a lower case 17.

[0078] The upper cover 14 is made of, for example, synthetic resin and formed in a flat plate shape. Preferably, the upper cover 14 is a molded product of synthetic resin. The upper cover 14 is attached (adhered) to the upper surface of the upper flow path forming member 11 (the thin portion 11b thereof) via a double-sided adhesive sheet 18 formed in substantially the same shape as the upper cover 14.

[0079] The upper cover 14 has ventilation holes 141, 141 that connect the internal ventilation space 7 with the outside. The ventilation holes 141, 141 are arranged above a pair of first openings 112, 112 of the upper flow path forming member 11 that communicate with the internal ventilation space 7 (side spaces 7a, 7a).

[0080] Additionally, the upper cover 14 is formed with observation windows 142, 142 through which an observer can observe (the detectable result occurring in) the assay region 31c of the microchannel 31. The observation windows 142, 142 are disposed above the assay region 31c of the microchannel 31, more specifically, above the first assay reagent 6a and the second assay reagent 6b.

[0081] Furthermore, the upper cover 14 is formed with confirmation / ventilation windows 143, 143 that connect the storage space 5 that stores the first liquid absorbent material 4 with the outside and that allow the state (liquid absorption status, etc.) of the first liquid absorbent material 4 to be confirmed. The confirmation / ventilation windows 143, 143 are arranged above the first liquid absorbent material 4 and above the two through holes 113, 113 of the upper flow path forming member 11.

[0082] The back plate 15 is made of a white or black synthetic resin and is preferably a molded synthetic resin. The back plate 15 is accommodated in a recess 124 formed in the lower surface of the lower flow-path forming member 12. As described above, in this embodiment, the upper flow-path forming member 11 and the lower flow-path forming member 12 that form the internal flow path 3 are formed to be transparent. The recess 124 formed in the lower surface of the lower flow-path forming member 12 is large enough to accommodate most of the lower tapered portion 121b of the lower wall portion 121 that forms the lower wall of the microflow path 31. Therefore, by being accommodated in the recess 124 formed in the lower surface of the lower flow-path forming member 12, the back plate 15 is positioned below the assay region 31c of the microflow path 31. The back plate 15 accommodated in the recess 124 provides a white or black background for the assay region 31c, thereby facilitating an observer's observation of the assay region 31c (the detectable result occurring therein) through the observation windows 142.

[0083] Therefore, it is preferable that the color of the back plate 15 be appropriately selected depending on the detectable result occurring in the assay region 31 c. For example, when an observer needs to observe color development, absorbance, or the like through the observation windows 142, 142, a white back plate 15 is selected, and when an observer needs to observe luminescence, fluorescence, or the like through the observation windows 142, 142, a black back plate 15 is selected.

[0084] The second liquid absorbent 16 is formed of a porous material capable of absorbing liquid, similar to the first liquid absorbent 4. The second liquid absorbent 16 is formed larger than the first liquid absorbent 4 and is disposed below the first liquid absorbent 4 and the lower flow path forming member 12. The second liquid absorbent 16 absorbs liquid mainly via the first liquid absorbent 4.

[0085] The lower case 17 is made of, for example, synthetic resin, and is preferably a molded product of synthetic resin. The lower case 17 has an upper opening containing section 171 for containing the second liquid absorbent 16, and a support surface 172 for supporting the lower surface of the back plate 15 contained in a recess 124 formed in the lower surface of the lower flow path forming member 12. In addition, six pin holes 173 are formed on the periphery of the upper surface of the lower case 17, into which six pins 125 protruding from the lower surface of the lower flow path forming member 12 are fitted.

[0086] The assay device 1 shown in FIG. 1 is obtained by assembling the members (components) shown in FIG.

[0087] Next, the movement of liquid in the assay device 1 will be described with reference to Figures 8A to 10F.

[0088] 8A to 8D are diagrams illustrating the movement of a liquid (hereinafter referred to as the "first liquid LQ1") injected into the assay device 1, and FIGS. 9A to 9D are diagrams illustrating the movement of a liquid (hereinafter referred to as the "second liquid LQ2") injected into the assay device 1, and schematically show the internal flow path 3 and other components when the assay device 1 is viewed from above. In FIGS. 8A to 8D and 9A to 9D, the first liquid LQ1 and the second liquid LQ2 are indicated by hatching. FIGS. 10A to 10F are schematic cross-sectional views of the boundary region between the separation flow path 32 and the first liquid absorbent 4, showing how the liquid is separated on the upstream side of the first liquid absorbent 4. FIG. 10A shows the state before the liquid reaches the separation flow path 32.

[0089] 8A, the first liquid LQ1 enters (is supplied to) the microchannel 31. The first liquid LQ1 that has entered the microchannel 31 flows smoothly toward the separation channel 32.

[0090] As the injection of the first liquid LQ1 continues and an amount of the first liquid LQ1 that exceeds the capacity of the microchannel 31 is supplied, the first liquid LQ1 flows into the separation channel 32. Here, as shown in FIG. 10B, the bottom wall of the separation channel 32 is inclined downward so that the height position becomes lower the closer it is to the first liquid absorbent material 4. For this reason, as shown in FIG. 8B, the first liquid LQ1 that has flowed into the separation channel 32 flows through the separation channel 32 toward the first liquid absorbent material 4 and comes into contact with the first liquid absorbent material 4. The first liquid LQ1 is then absorbed into the first liquid absorbent material 4 by the capillary force of the first liquid absorbent material 4.

[0091] At this time, the first liquid LQ1, which flows smoothly through the downwardly inclined separation flow path 32, passes through the obstacle-forming members 410a, 410b, comes into contact with the first liquid absorbent material 4, and is absorbed, as shown in Figures 10C and 10D.

[0092] Thereafter, when the injection of the first liquid LQ1 is stopped, the first liquid LQ1 from the injection port 2 flows toward the first liquid absorbent material 4, and then the first liquid LQ1 from the microchannel 31 stops flowing into the separation channel 32. At this time, the capillary force of the first liquid absorbent material 4 acts on the first liquid LQ1, and so the first liquid LQ1 is pulled by the microchannel 31 and the first liquid absorbent material 4, as shown by the arrows in Figures 8C and 10E.

[0093] In this embodiment, the separation channel 32, located between the microchannel 31 and the first liquid absorbent 4, is provided with obstacle-forming members 410a and 410b, which function as flow channel surface changing portions that change the surface of the separation channel 32. The first liquid LQ1 is pulled to one side (upstream) by the interfacial tension of the liquid in the microchannel 31 and to the other side (downstream) by the capillary force of the first liquid absorbent 4. The presence of the obstacle-forming members 410a and 410b changes the flow channel surface with which the first liquid LQ1 comes into contact, making it more likely to be separated into the upstream and downstream sides. The separation channel 32 further has a narrow width portion 321, where the flow channel width is narrowed. Therefore, the first liquid LQ1 in the microchannel 31 upstream of the narrow width portion 321 is strongly retained in the microchannel 31 by the interfacial tension, and the first liquid LQ1 in the microchannel 31 is prevented from flowing downstream beyond the narrow width portion 321. On the other hand, the first liquid LQ1 present on the downstream side of the narrow width portion 321 is sucked in by the capillary force of the first liquid absorbent material 4.

[0094] As a result, the first liquid LQ1 in the internal flow path 3 is divided on the upstream side of the first liquid absorbent material 4. As a result, as shown in FIG. 8D and FIG. 10F, a portion of the first liquid LQ1 (the portion on the downstream side of the narrow width portion 321) is absorbed by the first liquid absorbent material 4, while the remainder is retained on the upstream side of the narrow width portion 321, that is, mainly within the microflow path 31. As a result, the first liquid LQ1 in the internal flow path 3 is separated into the portion absorbed by the first liquid absorbent material 4 and the portion retained within the microflow path 31.

[0095] In this manner, in this embodiment, obstacle-forming members 410a, 410b that function as flow path surface changing portions are provided in the separation flow path 32, and further, a narrow width portion 321 is provided, so that even if the first liquid LQ1 has a small (weak) interfacial tension, it will not be sucked from the micro flow path 31 into the first liquid absorbent 4 due to the capillary force of the first liquid absorbent 4.

[0096] As a result, the first liquid LQ1 in the internal flow channel 3 is stably separated at the separation flow channel 32; in other words, the first liquid LQ1 can stably remain within the microflow channel 31. Then, as the first liquid LQ1 remains within the assay region 31c, the first assay reagent 6a and / or the second assay reagent 6b react with the first liquid LQ1 or the sample contained therein, producing the detectable result. In other words, an assay is performed in the assay region 31c.

[0097] 9A to 9D are diagrams for explaining the movements of the first liquid LQ1 and the second liquid LQ2 when a new liquid (hereinafter referred to as the "second liquid LQ2") is injected after the injection of the first liquid LQ1 into the assay device 1 has stopped, and they schematically show the internal flow path 3 and other components when viewed from above the assay device 1. In Figures 9A to 9D, the first liquid LQ1 is shown with the same hatching as in Figures 8A to 8D, and the second liquid LQ2 is shown with hatching that differs from that of the first liquid LQ1.

[0098] 9A, when the second liquid LQ2 is injected after the injection of the first liquid LQ1 is stopped, the second liquid LQ2 enters (is supplied to) the microchannel 31 and, similar to the case of the first liquid LQ1, flows toward the separation channel 32. Here, as described above, the first liquid LQ1 is retained in the microchannel 31, but the first liquid LQ1 retained in the microchannel 31 is pushed out of the microchannel 31 by the newly injected second liquid LQ2, flows through the separation channel 32, comes into contact with the first liquid absorbent material 4, and is absorbed by the first liquid absorbent material 4.

[0099] As the injection of the second liquid LQ2 continues, and an amount of the second liquid LQ2 that exceeds the capacity of the microchannel 31 is supplied, in other words, an amount of the second liquid LQ2 that exceeds the amount of the first liquid LQ1 that had been retained in the microchannel 31, all of the first liquid LQ1 that had been retained in the microchannel 31 is pushed out of the microchannel 31. As a result, the first liquid LQ1 is replaced with the second liquid LQ2 in the microchannel 31. In other words, liquid exchange occurs in the microchannel 31. Then, as the second liquid LQ2 is further injected, the second liquid LQ2 flows from the microchannel 31 into the separation channel 32, and flows through the separation channel 32 toward the first liquid absorbent 4, coming into contact with the first liquid absorbent 4. As a result, the second liquid LQ2, following the first liquid LQ1, is absorbed by the first liquid absorbent 4 due to the capillary force of the first liquid absorbent 4.

[0100] Thereafter, when the injection of the second liquid LQ2 is stopped, the second liquid LQ2 from the injection port 2 flows toward the first liquid absorbent 4, and then the second liquid LQ2 in the microchannel 31 stops flowing into the separation channel 32. At this time, the capillary force of the first liquid absorbent 4 acts on the second liquid LQ2, and therefore, as shown in Fig. 9C, the microchannel 31 and the first liquid absorbent 4 mutually pull on the second liquid LQ2, just as in the case of the first liquid LQ1.

[0101] As in the case of the first liquid LQ1, the presence of the obstacle-forming members 410a and 410b promotes the division of the second liquid LQ2 on the upstream side of the first liquid absorbent 4, and the second liquid LQ2 on the downstream side of the narrow width portion 321 is sucked in by the capillary force of the first liquid absorbent 4. On the other hand, the second liquid LQ2 in the microchannel 31 on the upstream side of the narrow width portion 321 is tightly retained in the microchannel 31 by interfacial tension, and the second liquid LQ2 in the microchannel 31 is prevented from passing over the narrow width portion 321 and flowing downstream thereof.

[0102] 9D, a portion of the second liquid LQ2 (the portion on the downstream side of the narrow width portion 321) is absorbed by the first liquid absorbent 4, and the remainder is retained on the upstream side of the narrow width portion 321, that is, mainly within the microchannel 31. Furthermore, as the second liquid LQ2 remains within the microchannel 31, an assay is carried out in the assay region 31c, just as in the case of the first liquid LQ1.

[0103] As described above, when the liquid in the microchannel 31 is absorbed by the first liquid absorbent 4, interfacial tension also acts on the liquid. However, the liquid is more likely to be cut off at the location where interfacial tension acts least, i.e., near the boundary between the other end of the separation channel 32 and the first liquid absorbent 4. The flow channel surface change portions 410a, 410b are provided near the boundary between the other end of the separation channel 32 and the first liquid absorbent 4, where interfacial tension acts least. Therefore, the liquid is effectively separated at this location. Thus, in the assay device 1, even if the interfacial tension is small (weak), after the injection of the liquid is stopped, the liquid in the internal flow channel 3 is stably separated by the separation channel 32 and can stably remain in the microchannel 31. Furthermore, when a liquid (e.g., the first liquid LQ1) is retained in the microchannel 31, liquid exchange occurs in the microchannel 31 by injecting new liquid (e.g., the second liquid LQ2) in an amount exceeding the amount of the liquid (e.g., the first liquid LQ1) retained in the microchannel 31. In other words, the assay device 1 can stably exchange liquids within the microchannel 31 even for liquids with low (weak) interfacial tension. Such stable liquid exchange can facilitate the occurrence of multi-stage antigen-antibody reactions in ELISA and other methods. In the assay device 1, the narrow section 321 is provided in the separation channel 32, which can more effectively separate the liquids. However, the narrow section 321 is not essential, and the separation channel 32 can also be configured without the narrow section 321.

[0104] The assay device 1 according to the present embodiment described above can provide the following advantageous effects.

[0105] The assay device 1 has an inlet 2, an internal flow channel 3 through which a liquid injected from the inlet 2 flows, and a first liquid absorbent 4 that absorbs the liquid that has passed through the internal flow channel 3. The internal flow channel 3 includes a microflow channel 31 having an assay region 31c, and a separation flow channel 32 that is provided between the microflow channel 31 and the first liquid absorbent 4 and that separates the liquid in the internal flow channel 3 into a portion that is retained in the microflow channel 31 and a portion that is absorbed by the first liquid absorbent 4 when the injection of the liquid is stopped, and the separation flow channel 32 has obstacle-forming members 410a, 410b as flow channel surface changing parts that change the surface of the separation flow channel 32 that comes into contact with the liquid.

[0106] In the assay device 1, when the injection of liquid is stopped, the liquid in the injection port 2 flows toward the first liquid absorbent material 4, and then the microchannel 31 and the first liquid absorbent material 4 start to pull on each other (see FIGS. 8C and 10E). At this time, the liquid in the microchannel 31 tries to remain in the microchannel 31 strongly due to its own interfacial tension. The presence of the flow channel surface changing portions 410a and 410b makes the flow of liquid more easily disrupted. Even if the interfacial tension of the liquid in the internal flow channel 3 is small, the liquid is stably disrupted downstream of the separation flow channel 32, i.e., upstream of the first liquid absorbent material 4, and the liquid can be stably retained in the microchannel 31. Therefore, there is almost no risk of air being mixed into the microchannel 31, and the liquid can be stably exchanged in the microchannel 31, allowing the assay in the microchannel 31 to proceed stably.

[0107] The flow channel surface change portions 410a and 410b have a step structure that creates a step in the separation channel 32, and therefore the step can promote separation of the liquid.

[0108] The step structure of the flow path surface change section is formed from a material that is impermeable to liquid and includes obstacle-forming members 410a, 410b installed at the upstream end of the first liquid absorbent 4 in the liquid flow direction, so the step structure can be easily formed.

[0109] The obstacle-forming members 410a, 410b are placed on at least one of the upper and lower surfaces of the first liquid absorbent 4 depending on the height of the separation flow path 32 and the composition of the liquid injected into the assay device 1 to promote separation of the liquid.

[0110] [Second embodiment] Figures 11 and 12 show an assay device 10 according to a second embodiment. Figure 11 is a perspective view of the assay device 10, and Figure 12 is an exploded perspective view of the assay device 10. In Figures 11 and 12, elements common to the assay device 1 according to the first embodiment are designated by the same reference numerals and their description will be omitted.

[0111] The main difference between the assay device 1 of the first embodiment and the assay device 10 of the second embodiment is that the assay device 1 of the first embodiment has one injection port 2 and one internal flow path 3, whereas the assay device 10 of the second embodiment has multiple injection ports 2 and multiple internal flow paths 3 (here, three of each), and accordingly, additional features such as an air vent 141 and an observation window 142 are also provided.

[0112] The first liquid absorbent 4 is arranged to absorb the liquid that has passed through the multiple internal flow paths 3, and obstacle-forming members 410a, 410b that function as flow path surface changers that change the surfaces of the separation flow paths 32 that come into contact with the liquid are installed on at least one of the upper and lower surfaces of the upstream end of the upper absorbent 4a. The dimension of the obstacle-forming members 410a, 410b in the width direction W is substantially the same as the dimension of the upper absorbent 4a in the width direction W. Other configurations are basically the same as those of the first embodiment.

[0113] The assay device 10 according to the second embodiment also provides the same effects as the assay device 1 according to the first embodiment. Furthermore, the assay device 10 according to the second embodiment can perform assays on multiple liquids simultaneously and in parallel.

[0114] [Third embodiment] In the first and second embodiments described above, the upper flow path forming member 11, the lower flow path forming member 12, the lower case 17, etc. are made of three-dimensional molded synthetic resin parts, and further, the separation flow path 32 is provided with a narrow width portion 321 where the flow path width is narrowed. In the third embodiment, the assay device is fabricated using a layered structure in which flat plate-shaped members are stacked, and the separation flow path has a simple configuration without a narrow width portion. The following mainly describes the differences from the first embodiment described above.

[0115] 13 shows a schematic cross-sectional view of an assay device 100 according to the third embodiment, and Fig. 14 shows an exploded perspective view of the assay device 100. The assay device 100 mainly includes an upper cover 150, an upper flow path forming member 110, an intermediate member 130, a first liquid absorbent 140, a lower flow path forming member 120, a housing member 160, a second liquid absorbent 170, and a lower case 180.

[0116] The upper flow path forming member 110 and the lower flow path forming member 120 are made of a transparent synthetic resin so as to be flexible, similar to the first embodiment described above. In this embodiment, similar to the first embodiment described above, the internal flow path 3 is formed by stacking the upper flow path forming member 110, the lower flow path forming member 120, and the intermediate member 130 that functions as a spacer between them.

[0117] Liquid injected from an inlet 2 located on one side in the longitudinal direction L of the assay device 100 (the right side in FIG. 13) flows through the internal flow path 3, and the liquid that passes through the internal flow path 3 is absorbed by a first liquid absorbent 140 located on the other side in the longitudinal direction L (the left side in FIG. 13). The first liquid absorbent 140 is formed in a block shape from a flexible porous material or the like that is capable of absorbing liquid. As in the first embodiment, the first liquid absorbent 140 is provided with obstacle-forming members 411a, 411b that function as flow path surface changing parts that change the surface of the separation flow path 32 that comes into contact with the liquid, in order to promote separation of the liquid on one side, i.e., the upstream side, of the first liquid absorbent 140.

[0118] The upper flow path forming member 110 is formed as a flat plate-like member having a rectangular outer shape in top view. The upper flow path forming member 110 is formed with a first circular hole 111 that is circular in top view and a pair of first slit holes 112, 112 that are rectangular in top view. The first circular hole 111 and the pair of first slit holes 112, 112 penetrate the upper flow path forming member 110 in the height direction H. In the upper flow path forming member 110, an upper wall portion 117 that constitutes the upper wall of the internal flow path 3 is formed by a first inter-slit region 114 sandwiched between the pair of first slit holes 112, 112.

[0119] The lower flow path forming member 120 is formed as a flat plate-like member having approximately the same outer shape as the outer shape of the upper flow path forming member 110. The lower flow path forming member 120 is formed with a pair of second slit holes 122, 122 that are rectangular in top view, and a U-shaped hole 123 that is approximately U-shaped and facing sideways in top view. The pair of second slit holes 122, 122 and the U-shaped hole 123 penetrate the lower flow path forming member 120 in the height direction H.

[0120] The pair of second slit holes 122, 122 and the pair of straight line portions of the U-shaped hole 123 are formed to correspond to the pair of first slit holes 112, 112 of the upper flow path forming member 110. In other words, the pair of second slit holes 122, 122 and the pair of straight line portions of the U-shaped hole 123 are formed to be located below the pair of first slit holes 112, 112 of the upper flow path forming member 110 when the upper flow path forming member 110, the intermediate member 130, and the lower flow path forming member 120 are stacked.

[0121] A lower wall portion 127 that constitutes the lower wall of the internal flow path 3 is formed by a second inter-slit region 124 sandwiched between a pair of second slit holes 122, 122, an inner region 125 on the inside of the U-shaped hole 123, and a second connecting region 126 that connects the second inter-slit region 124 and the inner region 125. Furthermore, the second inter-slit region 124 and the second connecting region 126 form the lower wall of the microflow path 31, and the inner region 125 forms the lower wall of the separation flow path 32.

[0122] The upper cover 150 is formed into a flat plate shape from, for example, synthetic resin. The upper cover 150 has approximately the same outer shape as the upper flow path forming member 110, and is attached to the upper surface of the upper flow path forming member 110 using a double-sided adhesive sheet (not shown) or the like. The upper cover 150 is formed with a second circular hole 151 that is circular in top view and observation windows 152, 152 that are rectangular in top view. The second circular hole 151 and the observation windows 152, 152 penetrate the upper cover 150 in the height direction H.

[0123] In this embodiment, the injection port 2 is formed by a first circular hole 111 in the upper flow path forming member 110 and a second circular hole 151 in the upper cover 150. The observation windows 152, 152 are disposed above the first assay reagent 6a and the second assay reagent 6b in the assay region 31c of the microflow path 31.

[0124] The housing member 160 is made of, for example, a molded product of synthetic resin. The housing member 160 has an outer shape substantially the same as that of the lower flow path forming member 120, and is attached to the lower surface of the lower flow path forming member 120 using a double-sided adhesive sheet (not shown) or the like. The housing member 160 has an opening 161 that is rectangular in top view. The opening 161 penetrates the housing member 160 in the height direction H.

[0125] The lower case 180 is made of, for example, a molded product of synthetic resin. The lower case 180 has an outer shape substantially the same as that of the housing member 160, and is attached to the lower surface of the housing 160 using a double-sided adhesive sheet (not shown) or the like. The lower case 180 has a storage section 181 with an opening on the top surface for storing the second liquid absorbent 170. The second liquid absorbent 170 is formed in a block shape that is larger than the first liquid absorbent 140, and is placed inside the storage section 181 of the lower case 180.

[0126] As in the first embodiment described above, the obstacle-forming members 411a and 411b can be formed by placing double-sided adhesive sheets on the upper and lower surfaces of a sheet material, respectively. The obstacle-forming members 411a and 411b are attached to the upper and lower surfaces of the first liquid absorbent 140 via the double-sided adhesive sheets. More specifically, the obstacle-forming member 411a is placed on the upper surface of one side, i.e., the upstream end, of the first liquid absorbent 140, and the obstacle-forming member 411b is placed on the lower surface of one side, i.e., the upstream end, of the first liquid absorbent 140. However, this is not limited thereto, and the obstacle-forming members 411a and 411b may be placed on only one of the upper and lower surfaces of the first liquid absorbent 140.

[0127] The assay device 100 shown in Fig. 13 is obtained by assembling the members (components) shown in Fig. 14. As described above, the obtained assay device 100 has an inlet 2 on its upper surface through which a liquid is injected, an internal flow path 3 through which the liquid injected from the inlet 2 flows, and a first liquid absorbent 140 that absorbs the liquid that has passed through the internal flow path 3. The internal flow path 3 includes a microflow path 31 that communicates with the inlet 2, and a separation flow path 32 that is provided between the microflow path 31 and the first liquid absorbent 140 and that separates the liquid in the internal flow path 3 when the injection of the liquid is stopped.

[0128] When the upper flow path-forming member 110, the lower flow path-forming member 120, and the intermediate member 130 are stacked and integrated, the first liquid absorbent 140 is disposed on the downstream end side of the U-shaped hole 123 of the lower flow path-forming member 120, and therefore the inner portion 125 of the lower flow path-forming member 120 is bent and deformed downward by being pressed against the block-shaped first liquid absorbent 140. Therefore, when the upper flow path-forming member 110, the lower flow path-forming member 120, and the intermediate member 130 are stacked and integrated, a separation flow path 32 is formed that extends from the microflow path 31 toward the first liquid absorbent 140 and has a downwardly sloping lower wall that becomes lower as it approaches the first liquid absorbent 140.

[0129] When liquid is injected from the inlet 2, as in the first embodiment described above, the liquid in the internal flow path 3 is subjected to a force that tries to keep the liquid in the microflow path 31 due to interfacial tension and a capillary force of the first liquid absorbent 140, resulting in a state in which the liquid is pulled by the microflow path 31 and the first liquid absorbent 140. At this time, the liquid being pulled from the upstream and downstream sides is easily separated into the upstream and downstream sides by the presence of the obstacle-forming members 411a and 411b.

[0130] Thereafter, when the injection of the liquid is stopped, the liquid in the internal flow path 3 is separated in the separation flow path 32, with a portion of the liquid being absorbed by the first liquid absorbent 140 and the remainder being retained in the micro flow path 31. In other words, the liquid in the internal flow path 3 is separated into a portion that is retained in the micro flow path 31 and a portion that is absorbed by the first liquid absorbent 140.

[0131] In the third embodiment described above, by providing obstacle-forming members 411a, 411b in the separation channel 32, it is possible to achieve the same effects as in the first embodiment. Furthermore, by making the separation channel 32 have a linear structure that does not include a narrow section 321, it is possible to make the internal channel 3 a tapered channel or a straight channel as a whole. Note that the assay device 100 according to the third embodiment may also be configured to have a plurality of injection ports 2 and internal channels 3, as in the second embodiment described above.

[0132] [Fourth embodiment] The present invention can also be applied to an assay device configured to use a small amount of liquid and to perform an assay by electrochemical method. In the fourth embodiment, in an assay device that performs an assay by electrochemical method, a flow path surface changing portion that changes the surface of the separation flow path 32 is provided to promote separation of the liquid, similar to the above-mentioned embodiments.

[0133] The assay device according to the fourth embodiment is configured using a laminated structure in which flat plate-like members are stacked, similar to the third embodiment. The following mainly describes the differences from the third embodiment.

[0134] Fig. 15 is an exploded perspective view of an assay device 1000 according to the fourth embodiment. Figs. 16A and 16B show a structure 20 (including a first liquid absorbent material 140) in which an upper flow path forming member 110, a lower flow path forming member 120, and an intermediate member 130 are stacked and integrated, Fig. 16A is a perspective view of the structure 20, and Fig. 16B is a cross-sectional view taken along line BB of Fig. 16A.

[0135] The assay device 1000 mainly comprises an upper cover 150, an upper housing 155, an upper flow path forming member 110, an intermediate member 130, a first liquid absorbent 140, a lower flow path forming member 120, a second liquid absorbent 170, a lower housing 180, and a lower cover 190. As in the third embodiment described above, the upper flow path forming member 110, the lower flow path forming member 120, and the intermediate member 130 that functions as a spacer between them are stacked to form an internal flow path 3.

[0136] Liquid injected from an inlet 2 located on one side of the longitudinal direction L of the assay device 100 (the left side in FIG. 16B) flows through the internal flow path 3, and the liquid that passes through the internal flow path 3 is absorbed by a first liquid absorbent 140 located on the other side of the longitudinal direction L (the right side in FIG. 16B). The first liquid absorbent 140 is formed in a block shape from a flexible porous material or the like that is capable of absorbing liquid. As in the third embodiment, the first liquid absorbent 140 is provided with obstacle-forming members 411a, 411b that function as flow path surface changing parts that change the surface of the separation flow path 32 that comes into contact with the liquid, in order to promote separation of the liquid on one side of the first liquid absorbent 140, i.e., the upstream side.

[0137] The upper flow path forming member 110 is formed as a flat plate-like member having a rectangular outer shape in a top view. The upper flow path forming member 110 is formed with a first circular hole 111 that is circular in a top view, a pair of first slit holes 112, 112 that are rectangular in a top view, and a U-shaped hole 113 that is substantially U-shaped in a sideways direction in a top view. The first circular hole 111, the pair of first slit holes 112, 112, and the U-shaped hole 113 penetrate the upper flow path forming member 110 in the height direction H. An upper wall portion 117 that constitutes the upper wall of the internal flow path 3 is formed by a first inter-slit region 114 sandwiched between the pair of first slit holes 112, 112, an inner region 115 inside the U-shaped hole 113, and a first connecting region 116 that connects the first inter-slit region 114 and the inner region 115. The first inter-slit region 114 and the first connection region 116 form the upper wall of the microchannel 31, and the inner region 115 forms the upper wall of the separation channel 32.

[0138] The lower flow path forming member 120 is formed as a flat plate-like member having approximately the same outer shape as the outer shape of the upper flow path forming member 110. A pair of second slit holes 122, 122 having a rectangular shape in top view and a pair of third slit holes 123, 123 having a rectangular shape in top view are formed in the lower flow path forming member 120. The pair of second slit holes 122, 122 and the pair of third slit holes 123, 123 penetrate the lower flow path forming member 120 in the height direction H.

[0139] The pair of second slit holes 122, 122 are formed to correspond to the pair of first slit holes 112, 112 of the upper flow path forming member 11. The pair of third slit holes 123, 123 are formed to correspond to a pair of straight line portions of the U-shaped hole 113 of the upper flow path forming member 11.

[0140] A second inter-slit region 124 sandwiched between a pair of second slit holes 122, 122, a third inter-slit region 125 sandwiched between a pair of third slit holes 123, 123, and a second connection region 126 connecting the second inter-slit region 124 and the third inter-slit region 125 form a lower wall portion 127 that constitutes the lower wall of the internal flow path 3. Furthermore, the second inter-slit region 124 and the second connection region 126 form the lower wall of the microflow path 31, and the third inter-slit region 125 forms the lower wall of the separation flow path 32.

[0141] Furthermore, the lower flow-path forming member 12 is formed with an electrode portion 51, a connection portion 52, and a conductor portion 53 for electrochemical assay. Specifically, in this embodiment, the electrode portion 51, the connection portion 52, and the conductor portion 53 are integrally formed with the lower flow-path forming member 12 by printing a conductive material on the upper surface of the lower flow-path forming member 12. Examples of conductive materials include, but are not limited to, conductive carbon, gold, silver, silver chloride, platinum, nickel, graphite, palladium, iron, copper, zinc, carbon paste, mesh electrodes, diamond, and ITO (indium-tin oxide) electrodes. The electrode portion, the connection portion, and the conductor portion are preferably printed with the same material, but may be printed with different materials. Since the electrochemical assay is not directly related to the separation of liquid in the separation channel 32, details thereof will be omitted.

[0142] The upper housing 155 is made of, for example, a molded product of synthetic resin. The upper housing 155 has an outer shape substantially the same as that of the upper flow path forming member 110, and is attached to the upper surface of the upper flow path forming member 110 using a double-sided adhesive sheet (not shown) or the like. The upper housing 155 is formed with a second circular hole 156 that is circular in a top view, a first window hole 157 that is rectangular in a top view, and an opening 158 that is rectangular in a top view. The second circular hole 156, the first window hole 157, and the opening 158 penetrate the upper housing 14 in the height direction H.

[0143] The second circular hole 156 is formed at a position corresponding to the first circular hole 111 of the upper flow path forming member 110, and constitutes a part of the injection port 2. The first window hole 157 is formed so as to be located above the electrode part 51 of the lower flow path forming member 120, and constitutes a part of the observation window 7. The opening 158 is formed at a position corresponding to the U-shaped hole 113 of the upper flow path forming member 110, and has a size that can accommodate the U-shaped hole 113.

[0144] The upper cover 150 is made of, for example, a molded product of synthetic resin. The upper cover 150 is formed in a flat plate shape and has an outer shape substantially the same as that of the upper housing 155. The upper cover 150 is attached to the upper surface of the upper housing 155 using a double-sided adhesive sheet (not shown) or the like. The circular third circular hole 151 and the rectangular second window hole 152 formed in the upper cover 150 penetrate the upper cover 150 in the height direction H.

[0145] In this embodiment, the injection port 2 is formed by the first circular hole 111 in the upper flow path forming member 110, the second circular hole 156 in the upper housing 155, and the third circular hole 151 in the upper cover 150. The observation window 7 is formed by the first window hole 157 in the upper housing 155 and the second window hole 152 in the upper cover 150.

[0146] The pair of third liquid absorbents 175, 175 are formed of a porous material or the like capable of absorbing liquid, similar to the first liquid absorbent 140. The pair of third liquid absorbents 175, 175 are each formed in an elongated block shape, and are arranged on the other side in the longitudinal direction L within the pair of third slit holes 123, 123 of the lower flow path forming member 120.

[0147] The second liquid absorbent 170, like the first liquid absorbent 140 and the pair of third liquid absorbents 175, 175, is formed of a block-shaped porous material or the like that is capable of absorbing liquid.

[0148] The lower housing 180 is made of, for example, a molded product of synthetic resin. The lower housing 180 has an outer shape that is substantially the same as the outer shapes of the upper flow path forming member 110 and the upper housing 155, and is attached to the lower surface of the lower flow path forming member 120 using a double-sided adhesive sheet (not shown) or the like. The lower housing 180 has an accommodating section 181 with an upper opening for accommodating the second liquid absorbent material 170.

[0149] Lower cover 190 is made of, for example, a molded product made of synthetic resin. Lower cover 190 is formed in a flat plate shape and has an outer shape that is approximately the same as the outer shape of lower housing 180. Lower cover 190 is attached to the lower surface of lower housing 180 using a double-sided adhesive sheet (not shown) or the like.

[0150] The obstacle-forming members 411a and 411b may be formed by placing double-sided adhesive sheets on the upper and lower surfaces of a sheet material, respectively, as in the third embodiment described above. The obstacle-forming members 411a and 411b are attached to the upper and lower surfaces of the first liquid absorbent 140 via the double-sided adhesive sheets. More specifically, the obstacle-forming member 411a is placed on the upper surface of one side, i.e., the upstream end, of the first liquid absorbent 140, and the obstacle-forming member 411b is placed on the lower surface of one side, i.e., the upstream end, of the first liquid absorbent 140. However, this is not limited thereto, and the obstacle-forming members 411a and 411b may be placed on only one of the upper and lower surfaces of the first liquid absorbent 140.

[0151] 15 are assembled to obtain an assay device 1000. As described above, the obtained assay device 1000 has an inlet 2 on its upper surface through which a liquid is injected, an internal flow path 3 through which the liquid injected from the inlet 2 flows, and a first liquid absorbent 140 that absorbs the liquid that has passed through the internal flow path 3. The internal flow path 3 includes a microflow path 31 that communicates with the inlet 2, and a separation flow path 32 that is provided between the microflow path 31 and the first liquid absorbent 140 and that separates the liquid in the internal flow path 3 when the injection of the liquid is stopped.

[0152] 16A and 16B , when the upper flow path-forming member 110, the lower flow path-forming member 120, and the intermediate member 130 are stacked and integrated, the first liquid absorbent 140 is disposed on the other side in the longitudinal direction L within the opening 131 of the intermediate member 130, and therefore the inner portion 115 of the upper flow path-forming member 110 is brought into contact with and pressed by the first liquid absorbent 4, thereby being flexibly deformed upward. Therefore, when the upper flow path-forming member 110, the lower flow path-forming member 120, and the intermediate member 130 are stacked and integrated, a separation flow path 32 is formed that extends from the microflow path 31 toward the first liquid absorbent 140 and has an upper wall that is inclined upward so that it becomes higher as it approaches the first liquid absorbent 140.

[0153] When liquid is injected from the inlet 2, as in the first embodiment described above, the liquid in the internal flow path 3 is subjected to a force that tries to keep the liquid in the microflow path 31 due to interfacial tension and a capillary force of the first liquid absorbent 140, resulting in a state in which the liquid is pulled by the microflow path 31 and the first liquid absorbent 140. At this time, the liquid being pulled from the upstream and downstream sides is easily separated into the upstream and downstream sides by the presence of the obstacle-forming members 411a and 411b.

[0154] Thereafter, when the injection of the liquid is stopped, the liquid in the internal flow path 3 is separated in the separation flow path 32, with a portion of the liquid being absorbed by the first liquid absorbent 140 and the remainder being retained in the micro flow path 31. In other words, the liquid in the internal flow path 3 is separated into a portion that is retained in the micro flow path 31 and a portion that is absorbed by the first liquid absorbent 140.

[0155] In the fourth embodiment described above, even if the upper wall of the separation channel 32 is slanted upward so that it becomes higher as it approaches the first liquid absorbent material 140, by providing obstacle-forming members 411a, 411b, it is possible to achieve the same effects as in the first embodiment described above. Furthermore, the assay device 1000 according to the fourth embodiment may also be configured to have a plurality of injection ports 2 and internal channels 3, as in the second embodiment described above.

[0156] -Variation 1- In the first to fourth embodiments described above, the obstacle-forming members 410a, 410b, 411a, 411b are provided on the first liquid absorbent 4, 140 as flow path surface changing parts that change the surface of the separation flow path 32 that comes into contact with the liquid, so as to create a step in the separation flow path 32. However, the configuration of the flow path surface changing part is not limited to this, as long as it can change the surface of the separation flow path 32 that comes into contact with the liquid and promote separation of the liquid.

[0157] For example, as a step structure of the flow path surface changing portion, a protrusion that protrudes into the separation flow path 32 can be provided on at least one of the upper and lower wall portions of the internal flow path 3. Specifically, as shown in Fig. 17, protrusions 420a and 420b can be formed as steps that protrude from the upper flow path forming member 11A and the lower flow path forming member 12A that constitute the upper and lower walls of the internal flow path 3. The protrusions 420a and 420b are disposed at positions corresponding to the upstream end of the first liquid absorbent 4 in the direction of liquid flow, and extend in the width direction W of the first liquid absorbent 4. The dimension in the height direction H of the protrusions 420a and 420b is set according to the height of the separation flow path 32 and the composition of the liquid injected into the assay device 1, etc., so as to promote separation of the liquid.

[0158] The protrusions 420a, 420b may be formed on only one of the upper flow path forming member 11A and the lower flow path forming member 12A. The protrusions 420a, 420b may also be arranged upstream of the upstream end of the first liquid absorbent 4, i.e., at the other end (downstream end) of the separation flow path 32. In other words, the protrusions 420a, 420b can be arranged near the boundary between the other end of the separation flow path 32 and the first liquid absorbent 4.

[0159] The protrusions 420a, 420b may be formed integrally with the upper flow path forming member 11A and the lower flow path forming member 12A, for example, as a three-dimensional molded product, or may be formed as separate members from the upper flow path forming member 11A and the lower flow path forming member 12A and joined to them.

[0160] -Variation 2- As a step structure of the flow path surface changing portion, a groove can be provided in at least one of the upper wall and lower wall of the internal flow path 3. Specifically, as shown in Fig. 18, grooves 430a and 430b can be formed as recesses formed in the upper flow path forming member 11B and the lower flow path forming member 12B that constitute the upper and lower walls of the internal flow path 3. The grooves 430a and 430b are disposed at positions corresponding to the upstream end of the first liquid absorbent 4 in the direction of liquid flow, and extend in the width direction W of the first liquid absorbent 4. The dimension in the height direction H of the grooves 430a and 430b is set according to the height of the separation flow path 32 and the composition of the liquid injected into the assay device 1 so as to promote separation of the liquid.

[0161] The grooves 430a, 430b may be formed in only one of the upper flow path forming member 11B and the lower flow path forming member 12B. The grooves 430a, 430b may also be located upstream of the upstream end of the first liquid absorbent 4, i.e., at the other end (downstream end) of the separation flow path 32. In other words, the grooves 430a, 430b can be located near the boundary between the other end of the separation flow path 32 and the first liquid absorbent 4.

[0162] -Variation 3- The flow path surface changing portion is not limited to a stepped structure, as long as it can change the surface of the separation flow path 32 that comes into contact with the liquid. For example, as shown in Fig. 19, the lower flow path forming member 12C that constitutes the lower wall of the internal flow path 3 can be formed as a member in which a first member 12Ca, which is located upstream of the upstream end of the first liquid absorbent 4 in the liquid flow direction, and a second member 12Cb, which is located downstream of the upstream end of the first liquid absorbent 4, are joined together, and the junction 440 between the first member 12Ca and the second member 12Cb can be used as the flow path surface changing portion. The liquid being pulled from the upstream and downstream sides in the separation flow path 32 is easily separated into the upstream and downstream sides by the presence of the junction (seam) 440, thereby facilitating separation of the liquid upstream of the first liquid absorbent 4. Instead of or in addition to the joint 440 of the lower flow path forming member 12C, a joint (seam) may be provided in the upper flow path forming member 11C that constitutes the upper wall of the internal flow path 3.

[0163] -Variation 4- The flow channel surface change portion is not limited to the shape change of the surface of the separation channel 32 as described above, as long as it can bring about a change in the surface of the separation channel 32 that comes into contact with the liquid. For example, the surface of the separation channel 32 that comes into contact with the liquid can be subjected to a surface treatment to promote liquid separation. This surface treatment includes a treatment that partially changes the polarity of the surface of the separation channel 32 to hydrophobicity. As an example, a hydrophobic surface treatment is performed on the surface region near the boundary between the other end of the separation channel 32 and the first liquid absorbent 4 on at least one of the upper channel-forming member 11 and the lower channel-forming member 12 that form the upper and lower walls of the internal channel 3. The range (area) to which the surface treatment is applied is determined depending on the height of the separation channel 32 and the composition of the liquid injected into the assay device 1, etc., so as to promote liquid separation. This promotes liquid separation upstream of the first liquid absorbent 4.

[0164] Although the embodiments and their modifications of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications and variations are possible based on the technical concept of the present invention. Furthermore, the above-described embodiments and their modifications can be combined in any desired manner. [Explanation of symbols]

[0165] 1,10,100,1000...assay device, 2...inlet, 3...internal flow path, 4...first liquid absorbent, 4a...upper absorbent, 4b...lower absorbent, 11,11A,11B,11C,110...upper flow path forming member, 12,12A,12B,12C,120...lower flow path forming member, 12Ca...first member, 12Cb...second member, 13,130...intermediate member, 31...microflow path, 32...separation flow path, 111,117...upper wall portion, 121,127...lower wall portion, 410a,410b,411a,411b...obstacle forming member, 420a,420b...protrusion portion, 430a,430b...groove portion, 440...junction portion, LQ1...first liquid, LQ2...second liquid

Claims

1. An inlet; an internal flow path through which the liquid injected from the injection port flows; a liquid absorbent material that absorbs liquid that has passed through the internal flow path; 1. An assay device comprising: The internal flow path is a microchannel having an assay region; a separation flow path provided between the micro flow path and the liquid absorbent material, for separating the liquid in the internal flow path into a portion to be retained in the micro flow path and a portion to be absorbed by the liquid absorbent material when the injection of the liquid is stopped; Including, the separation channel has a channel surface changing portion that changes the surface of the separation channel that comes into contact with the liquid, the flow path surface change portion has a step structure that causes a step in the separation flow path, The step structure of the flow path surface change portion is formed from a material that is impermeable to liquid, and includes an obstacle-forming member installed at the upstream end of the liquid absorbent material in the flow direction of the liquid, in an assay device.

2. The assay device according to claim 1 , wherein the obstacle-forming member is disposed on at least one of the upper and lower surfaces of the liquid absorbent material.

3. An inlet; an internal flow path through which the liquid injected from the injection port flows; a liquid absorbent material that absorbs liquid that has passed through the internal flow path; 1. An assay device comprising: The internal flow path is a microchannel having an assay region; a separation flow path provided between the micro flow path and the liquid absorbent material, for separating the liquid in the internal flow path into a portion to be retained in the micro flow path and a portion to be absorbed by the liquid absorbent material when the injection of the liquid is stopped; Including, the separation channel has a channel surface changing portion that changes the surface of the separation channel that comes into contact with the liquid, the flow path surface change portion has a step structure that causes a step in the separation flow path, a lower flow path forming member having a lower wall portion that constitutes a lower wall of the internal flow path; an intermediate member joined to an upper surface of the lower flow path forming member; an upper flow path forming member joined to an upper surface of the intermediate member and having an upper wall portion that forms an upper wall of the internal flow path, the internal flow path is formed by the upper flow path forming member, the lower flow path forming member, and the intermediate member that functions as a spacer between the upper flow path forming member and the lower flow path forming member, An assay device in which the step structure of the flow path surface change portion is formed on at least one of the upper wall portion and the lower wall portion, and is a protrusion that protrudes into the inside of the separation flow path at a position corresponding to the upstream end of the liquid absorbent material in the flow direction of the liquid.

4. An inlet; an internal flow path through which the liquid injected from the injection port flows; a liquid absorbent material that absorbs liquid that has passed through the internal flow path; 1. An assay device comprising: The internal flow path is a microchannel having an assay region; a separation flow path provided between the micro flow path and the liquid absorbent material, for separating the liquid in the internal flow path into a portion to be retained in the micro flow path and a portion to be absorbed by the liquid absorbent material when the injection of the liquid is stopped; Including, the separation channel has a channel surface changing portion that changes the surface of the separation channel that comes into contact with the liquid, the flow path surface change portion has a step structure that causes a step in the separation flow path, a lower flow path forming member having a lower wall portion that constitutes a lower wall of the internal flow path; an intermediate member joined to an upper surface of the lower flow path forming member; an upper flow path forming member joined to an upper surface of the intermediate member and having an upper wall portion that forms an upper wall of the internal flow path, the internal flow path is formed by the upper flow path forming member, the lower flow path forming member, and the intermediate member that functions as a spacer between the upper flow path forming member and the lower flow path forming member, An assay device, wherein the step structure of the flow path surface change portion is a groove portion formed in at least one of the upper wall portion and the lower wall portion at a position corresponding to the upstream end of the liquid absorbent material in the flow direction of the liquid.

5. An inlet; an internal flow path through which the liquid injected from the injection port flows; a liquid absorbent material that absorbs liquid that has passed through the internal flow path; 1. An assay device comprising: The internal flow path is a microchannel having an assay region; a separation flow path provided between the micro flow path and the liquid absorbent material, for separating the liquid in the internal flow path into a portion to be retained in the micro flow path and a portion to be absorbed by the liquid absorbent material when the injection of the liquid is stopped; Including, the separation channel has a channel surface changing portion that changes the surface of the separation channel that comes into contact with the liquid, a lower flow path forming member having a lower wall portion that constitutes a lower wall of the internal flow path; an intermediate member joined to an upper surface of the lower flow path forming member; an upper flow path forming member joined to an upper surface of the intermediate member and having an upper wall portion that forms an upper wall of the internal flow path, the internal flow path is formed by the upper flow path forming member, the lower flow path forming member, and the intermediate member that functions as a spacer between the upper flow path forming member and the lower flow path forming member, the lower flow path forming member is a member formed by joining a first member arranged upstream of an upstream end of the liquid absorbent in the flow direction of the liquid, and a second member arranged downstream of the upstream end of the liquid absorbent, The assay device, wherein the flow path surface changing portion is a junction between the first member and the second member.

Images