Flow path device and method for manufacturing same

Abstract

A flow path device (1) is provided with: a base (4) having a first surface (4a) and a second surface (4b) that face away from each other; and a pair of first electrode (10) and second electrode (11). The base (4) has a flow path (7) that extends along the first surface (4a) and the second surface (4b), and the pair of first electrode (10) and second electrode (11) form an electric field that intersects the flow path (7) along a direction in which the first surface (4a) and the second surface (4b) face away.

Description

Flow channel device and manufacturing method thereof

[0001] The present invention relates to a flow channel device and a method for manufacturing the same.

[0002] Non-Patent Document 1, for example, discloses a device for separating specific particles, such as cells, from other particles by dielectrophoresis. In this device, a sample solution containing suspended particles is flowed through a flow channel formed on a glass substrate. When an AC voltage is applied to multiple pairs of electrodes adjacent to the flow channel, an electric field is formed within the flow channel between adjacent pairs of electrodes. This electric field exerts an attractive force (positive dielectrophoresis) or a repulsive force (negative dielectrophoresis) on the particles. As a result, the specific particles are separated from the other particles.

[0003] Niccolo Piacentini et al., “Separation of platelets from other blood cells in continuous-flow by dielectrophoresis field-flow-fractionation,” Biomicrofluidics. September 21, 2011, 5(3): 034122-034122-8.

[0004] In Non-Patent Document 1, the electrodes are planar electrodes in which multiple pairs of electrodes are formed along the surface of a glass substrate. With this planar electrode, an electric field is formed that crosses the flow path along the surface of the glass substrate. This electric field is formed only between adjacent pairs of electrodes. Since the distance between adjacent pairs of electrodes is restricted, the range over which the electric field acts is limited. Therefore, if the flow rate of the sample solution is high, it is not possible to sufficiently separate the microparticles. On the other hand, if the flow rate is low, the throughput of the device decreases.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a flow channel device capable of forming an electric field over a long range along a flow channel, and a method for manufacturing the same.

[0006] A flow path device according to a first aspect of the present invention comprises a base having a first surface and a second surface facing back to back, and a pair of first and second electrodes, wherein the base has a flow path extending along the first and second surfaces, and the pair of first and second electrodes form an electric field that intersects the flow path along the direction in which the first and second surfaces face back to back.

[0007] In the flow channel device according to the first aspect, the first electrode extends along the flow channel on the side of the first surface, and the second electrode extends along the flow channel on the side of the second surface.

[0008] In the flow channel device according to the first aspect, the first electrode is formed on the first surface and faces the flow channel, and the second electrode is formed on the second surface and faces the flow channel.

[0009] The flow path device according to the first aspect of the present invention comprises a third electrode formed on the first surface, facing the flow path while opposing the first electrode across the flow path, and a fourth electrode formed on the second surface, facing the flow path while opposing the second electrode across the flow path.

[0010] A flow path device according to a first aspect of the present invention comprises a first covering member provided on the first surface so as to cover the flow path, and a second covering member provided on the second surface so as to cover the flow path.

[0011] In the flow channel device according to the first aspect, the flow channel has a first flow channel portion that extends linearly.

[0012] In the flow path device according to the first aspect, the flow path has a first flow path portion that extends linearly and a pair of second flow path portions that branch off from the first flow path portion.

[0013] In the flow channel device according to the first aspect, the flow channel is exposed at the first surface and the second surface of the base.

[0014] In the flow channel device according to the first aspect, the base, the pair of the first electrode and the second electrode form a flexible printed circuit board.

[0015] A method for manufacturing a flow path device according to a second aspect of the present invention includes the steps of forming a first conductive region on a first surface of a base having a first surface and a second surface facing each other, forming a second conductive region on the second surface at a position corresponding to the first conductive region, and cutting out a flow path in the base in the first conductive region and the second conductive region, wherein by cutting out the flow path, a first electrode facing the flow path is formed on the first surface of the base, and a second electrode facing the flow path is formed on the second surface.

[0016] In the manufacturing method of the flow path device according to the second aspect, a third electrode facing the flow path while facing the first electrode across the flow path is formed on the first surface of the base by cutting out the flow path, and a fourth electrode facing the flow path while facing the second electrode across the flow path is formed on the second surface of the base.

[0017] In the method for manufacturing a flow channel device according to the second aspect, the flow channels are cut out by irradiating with laser light.

[0018] According to the present invention, it is possible to provide a flow channel device capable of forming an electric field over a long range along a flow channel, and a method for manufacturing the same.

[0019] 10 is a perspective view schematically showing the structure of a flow channel device 1 according to a first embodiment of the present invention; FIG. 11 is a plan view schematically showing the structure of a flow channel device 1 according to a first embodiment of the present invention; FIG. 12 is an exploded perspective view schematically showing the structure of a flow channel device 1 according to a first embodiment of the present invention; FIG. 13 is a perspective view of the base 4 alone as seen from the rear surface side of the base 4; FIG. 14 is an end view of a cross section taken along line 5-5 in FIG. 2; FIG. 15 is a partially enlarged cross section of the flow channel device 1, schematically showing the state of an electric field formed in a flow channel 7; FIG. 16 is a cross section taken along line 7-7 in FIG. 6; FIG. 17 is a diagram schematically showing a method for manufacturing a flow channel device 1 according to an embodiment of the present invention; FIG. 18 is a plan view schematically showing the structure of a flow channel device 1A according to a second embodiment of the present invention; FIG. 19 is an end view of a cross section taken along line 11-11 in FIG. 10; FIG. 19 is a partially enlarged cross section of the flow channel device 1A, schematically showing the state of an electric field formed in a flow channel 7A; and FIG. 20 is a plan view schematically showing the structure of a flow channel device 1B according to a third embodiment of the present invention.

[0020] An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view schematically illustrating the structure of a flow channel device 1 according to a first embodiment of the present invention. FIG. 2 is a plan view schematically illustrating the structure of the flow channel device 1 according to the first embodiment of the present invention. FIG. 3 is an exploded perspective view schematically illustrating the structure of the flow channel device 1 according to the first embodiment of the present invention. The flow channel device 1 is a device for separating (sorting) specific particles, such as cells, from other particles, such as cells, using, for example, dielectrophoresis. Note that, for convenience, the terms "up" and "down" are used in the following description, but these terms do not necessarily correspond to up and down in the direction of gravity.

[0021] 1 to 3, the flow path device 1 has a laminated structure in which multiple layers are stacked. Specifically, the flow path device 1 has a laminated structure of, from the top, a first covering member 2, a first cover 3, a base 4, a second cover 5, and a second covering member 6. The first covering member 2, the first cover 3, the base 4, the second cover 5, and the second covering member 6 are adhered to each other with an adhesive or the like. The flow path device 1 is formed, for example, from a thin plate that is rectangular in plan view and has a first surface, i.e., a front surface 1a, and a second surface, i.e., a back surface 1b, facing back to back. Note that, for convenience, in this example, the upper surface of the flow path device 1 is defined as the front surface 1a, and the lower surface of the flow path device 1 is defined as the back surface 1b, but the opposite may also be true.

[0022] The first covering member 2, the first cover 3, the base 4, the second cover 5, and the second covering member 6 are all formed from a flexible, transparent material. In this example, the first covering member 2 and the second covering member 6 are formed from a resin material such as polydimethylsiloxane (PDMS). The base 4, the first cover 3, and the second cover 5 are all formed from a resin material such as polyimide. The base 4, the first cover 3, and the second cover 5 form a flexible printed circuit board (FPC). The thickness of the FPC is set to, for example, about 100 μm. The flow path device 1 as a whole is flexible.

[0023] The flow path device 1 has a flow path 7 for flowing a sample solution in which a substance that is a particle is suspended. The flow path 7 extends along the front surface 1a and the back surface 1b within the flow path device 1. In this example, the flow path 7 has a first flow path portion 71 that extends linearly from one end to the other end, and a pair of second flow path portions 72, 72 that are connected at one end to the other end of the first flow path portion 71. The second flow path portions 72, 72 branch into two from the other end of the first flow path portion 71 and extend linearly to the other end, moving away from each other. As will be described later, the flow path 7 is formed in the first cover 3, the base 4, and the second cover 5, and its upper surface is covered with the first covering member 2 and its lower surface is covered with the second covering member 6.

[0024] A flow path inlet 73 opening on the surface 1a of the flow path device 1 is formed at one end of the first flow path portion 71. A flow path outlet 74 opening on the surface 1a of the flow path device 1 is formed at the other end of each second flow path portion 72. As described below, when separating a substance such as a fine particle of cells suspended in a sample solution, the sample solution is introduced into the flow path 7 from the flow path inlet 73. The sample solution that flows through the flow path 7 at a predetermined flow rate is collected from the two flow path outlets 74. A pair of first and second conductive pads 8 and 9 for applying a voltage to electrodes described below are exposed on the surface 1a of the flow path device 1. Each of the first and second conductive pads 8 and 9 is exposed, for example, in a notch 1c formed on the surface 1a of the flow path device 1. The notch 1c is formed in the first covering member 2 and the first cover 3 (see FIG. 3 ).

[0025] As is clear from FIG. 3 , the flow channel 7 is formed to penetrate the base 4, the first cover 3, and the second cover 5. That is, the flow channel 7 penetrates from the front surface to the back surface of the FPC formed from the base 4, the first cover 3, and the second cover 5. The front and back surfaces of the FPC are covered by the first covering member 2 and the second covering member 6, respectively. As a result, the upper and lower surfaces of the flow channel 7 are defined by the first covering member 2 and the second covering member 6, respectively. In this example, the flow channel 7 extends, for example, parallel to the side surfaces 1d and 1e on the long sides of the flow channel device 1 (see FIG. 2 ). A flow channel inlet 73 and a flow channel outlet 74 are formed in the first covering member 2. On the other hand, nothing is formed in the second closing member 6.

[0026] FIG. 4 is a perspective view of the base 4 alone, as viewed from the back side of the base 4. Referring to FIGS. 2 to 4 together, the base 4 is composed of a thin plate having a front surface 4a and a back surface 4b that face each other. In this example, the front surface 4a and the back surface 4b extend parallel to each other. The first conductive pad 8 and the second conductive pad 9 described above are formed on the front surface 4a of the base 4. In this example, the first conductive pad 8 and the second conductive pad 9 are exposed on the side surface 1d of the long side of the base 4 (see FIG. 1). The first conductive pad 8 is electrically connected to a first electrode 10 that is also formed on the front surface 4a of the base 4. Meanwhile, the second conductive pad 9 is electrically connected to a second electrode 11 that is formed on the back surface 4b of the base 4.

[0027] A first conductive pattern 12 extending along the front surface 4a of the base 4 is used to electrically connect the first conductive pad 8 and the first electrode 10. A second conductive pattern 13 extending along the front surface 4a and rear surface 4b of the base 4 is used to electrically connect the second conductive pad 9 and the second electrode 11. The second conductive pattern 13 extends from the second conductive pad 9 along the front surface 4a, and then extends along the rear surface 4b via a through-hole via 14 that penetrates the base 4 to be connected to the second electrode 11. In a plan view of the base 4, the first electrode 10 and the second electrode 11 are arranged at positions corresponding to each other. In this example, the first electrode 10 and the second electrode 11 are arranged at the same position and have the same outline in a plan view.

[0028] A first dummy electrode 15 corresponding to the first electrode 10 is further formed on the front surface 4a of the base 4. Similarly, a second dummy electrode 16 corresponding to the second electrode 11 is formed on the back surface 4b of the base 4. The first dummy electrode 15 faces the first electrode 10 across the flow path 7. The second dummy electrode 16 faces the second electrode 11 across the flow path 7. No conductive patterns are connected to these first dummy electrode 15 and second dummy electrode 16. The first conductive pad 8, the second conductive pad 9, the first electrode 10, the second electrode 11, the first conductive pattern 12, the second conductive pattern 13, the through-hole via 14, the first dummy electrode 15, and the second dummy electrode 16 are all made of a conductive material such as copper.

[0029] FIG. 5 is a cross-sectional end view taken along line 5-5 in FIG. 2. As shown in FIG. 5, the first electrode 10 and the second electrode 11 are arranged facing each other in the direction in which the front surface 4a and the back surface 4b of the base 4 face each other, in this case, in the thickness direction of the base 4 defined by the front surface 4a and the back surface 4b of the base 4. The thickness direction is perpendicular to the front surface 4a and the back surface 4b of the base 4. The first electrode 10 and the second electrode 11 face one side surface 7a of the flow channel 7. Furthermore, the first electrode 10 and the second electrode 11 face the flow channel 7 at the same length in the longitudinal direction of the flow channel 7 (see FIGS. 2 to 4). On the other hand, as shown in FIG. 5, the first dummy electrode 15 and the second dummy electrode 16 face the other side surface 7b of the flow channel 7. In this example, the side surface 7a and the side surface 7b are defined parallel to each other.

[0030] A power supply (not shown) is connected to the first conductive pad 8 and the second conductive pad 9. The power supply is, for example, an AC power supply that can apply a voltage of a variable voltage value at a variable frequency between the first electrode 10 and the second electrode 11. The first electrode 10 is the electrode on the voltage application side, while the second electrode 11 is the electrode on the ground side. As will be described later, when a voltage is applied between the first electrode 10 and the second electrode 11, an electric field is formed between the first electrode 10 and the second electrode 11. The formation of this electric field can exert a dielectrophoretic effect on the sample solution flowing through the flow channel 7.

[0031] The flow path device 1 includes an imaging device (not shown) and a light source (not shown). Both the imaging device and the light source may be disposed, for example, facing the front surface 1a of the flow path device 1, or may be disposed facing the back surface 1b. The imaging device can capture an image of the flow path 7 illuminated by the light source. For example, a substance flowing through the flow path 7 may be fluorescently dyed in advance, and fluorescence observation of the substance may be performed by observing the fluorescence emitted from the substance when illuminated by the light source. The imaging device may be disposed facing the front surface 1a, while the light source may be disposed facing the back surface 1b. Conversely, the imaging device may be disposed facing the back surface 1b, while the light source may be disposed facing the front surface 1a.

[0032] Next, a description will be given of how the flow channel device 1 is used. For example, a sample solution containing two types of substances, such as microparticles of cells, having different dielectric constants, and a solution for suspending the substances is prepared. A buffer solution may be mixed into the solution at a predetermined concentration to adjust the dielectric constant of the solution. The prepared sample solution is injected through the flow channel inlet 73. For example, the sample solution is extracted from the flow channel outlet 74 by negative pressure. As a result, the sample solution flows through the flow channel 7 at a predetermined flow rate. At this time, a voltage of a predetermined frequency and a predetermined voltage value is applied between the first electrode 10 and the second electrode 11. This voltage application forms an electric field between the first electrode 10 and the second electrode 11 in the flow channel 7 adjacent to the first electrode 10 and the second electrode 11. At this time, the flow channel 7 illuminated by the light source is imaged by the imaging device.

[0033] FIG. 6 is a partially enlarged cross-sectional view of the flow channel device 1, schematically illustrating the electric field formed in the flow channel 7. FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 6. As shown in FIG. 6, when a voltage is applied between the first electrode 10 and the second electrode 11, an electric field E is formed in the flow channel 7. In the flow channel device 1, the electric field E is formed in the direction in which the front surface 4a and the back surface 4b of the base 4 face each other, i.e., in the thickness direction of the flow channel 7, and intersects with the flow channel 7. As a result, as shown in FIG. 7, in the sample liquid flowing at a predetermined flow rate along the flow channel 7 from the flow channel inlet 73 to the flow channel outlet 74, this electric field E exerts a repulsive force F1 (negative dielectrophoresis) on a substance C1, which is a particle such as a cell having a dielectric constant smaller than that of the solution, while exerting an attractive force F2 (positive dielectrophoresis) on a substance C2, which is a particle such as a cell having a dielectric constant larger than that of the solution.

[0034] As a result, in the sample solution flowing through the flow channel 7 in the region adjacent to the first electrode 10 and the second electrode 11, substance C1, which has a smaller dielectric constant than the solution, migrates toward the side surface 7b of the flow channel 7, while substance C2, which has a larger dielectric constant than the solution, migrates toward the side surface 7a of the flow channel 7. Thus, substances C1 and C2 that have passed through the region adjacent to the first electrode 10 and the second electrode 11 flow separately into one second flow channel portion 72 and the other second flow channel portion 72 due to the difference in dielectric constant. Substance C1 on the side surface 7b of the flow channel 7 is extracted from the flow channel outlet 74 of one second flow channel portion 72 that is continuous with the side surface 7b. At the same time, substance C2 that has migrated to the side surface 7a of the flow channel 7 is extracted from the flow channel outlet 74 of the other second flow channel portion 72 that is continuous with the side surface 7a. As a result, substance C1 is separated from substance C2 by dielectrophoresis.

[0035] According to the flow channel device 1 described above, the first electrode 10 and the second electrode 11 are disposed adjacent to the flow channel 7 and facing each other in the thickness direction of the flow channel 7. As a result, the first electrode 10 and the second electrode 11 form an electric field E that crosses the flow channel 7 along the thickness direction of the flow channel 7. Because the first electrode 10 and the second electrode 11 are both disposed facing each other along the flow channel 7, a constant electric field E can be constantly formed over a relatively long range along the flow channel 7. Therefore, for example, even when the force generated by the electric field E is small, separation of the substance C can be more reliably performed. Furthermore, for example, even when the flow rate of the sample solution is high, separation of the substance C can be more reliably performed.

[0036] Next, a method for manufacturing a flow channel device 1 according to one embodiment of the present invention will be described. FIGS. 8 and 9 are diagrams schematically illustrating a method for manufacturing a flow channel device 1 according to one embodiment of the present invention. As shown in FIG. 8 , a first conductive region 41 is formed on a front surface 40a of a polyimide thin plate 40 that will form the base 4. The first conductive region 41 forms a first circuit pattern that resembles the contours of the first conductive pad 8, the second conductive pad 9, the first electrode 10, the first conductive pattern 12, a portion of the second conductive pattern 13, and the first dummy electrode 15. Similarly, a second conductive region 42 is formed on a rear surface 40b of the thin plate 40. The second conductive region 42 forms a second circuit pattern that resembles the contours of the second electrode 11, a portion of the second conductive pattern 13, and the second dummy electrode 16.

[0037] For example, to form the first conductive region 41, a copper foil layer is adhered to the surface 40a of the thin plate 40. A photoresist layer is laminated on the copper foil layer. For example, ultraviolet light is irradiated to predetermined areas of the photoresist layer. In the irradiated areas, the photoresist layer is hardened by exposure to light. The unhardened areas of the photoresist layer are removed. Thereafter, the copper foil layer is removed in areas other than the hardened photoresist layer by, for example, chemical etching. The photoresist layer is then removed. In this way, the first conductive region 41 is formed on the surface 40a of the thin plate 40. Note that a second conductive region 42 is also formed on the back surface 40b of the thin plate 40 by a similar method.

[0038] The regions of the front surface 40a and the back surface 40b that will become the second conductive pattern 13 are electrically connected by through-hole vias 43. To form the through-hole vias 43, for example, through holes are formed in the regions of the front surface 40a and the back surface 40b of the thin plate 40 where the first conductive region 41 and the second conductive region 42 overlap. Then, the through-hole vias 43 are formed in the through holes by, for example, plating or the like. After the first conductive region 41 and the second conductive region 42 are formed, polyimide covers (not shown) are attached to the front surface 40a and the back surface 40b of the thin plate 40, respectively, by adhesive or the like. These covers constitute the first cover 3 and the second cover 5. In this manner, the FPC 44 is manufactured.

[0039] As shown in FIG. 9 , the FPC 44 is subjected to, for example, laser ablation processing. Specifically, laser light is irradiated onto the FPC 44 along a pattern that resembles the flow channel 7 in an area that crosses the first conductive region 41 and the second conductive region 42. As a result, the polyimide and copper in the area irradiated with the laser light melt and evaporate. As a result, a pattern 45 that resembles the flow channel 7 is cut out of the FPC 44. The pattern 45 penetrates from the front surface 40 a to the back surface 40 b. Then, thin PDMS plates (not shown) are attached to the front surface 40 a and the back surface 40 b. Note that through holes corresponding to the flow channel inlet 73 and the flow channel outlet 74 are pre-formed in the thin plate attached to the front surface 40 a. The thin plates constitute the first covering member 2 and the second covering member 6. In this manner, the flow channel device 1 is manufactured.

[0040] According to the manufacturing method described above, a pattern 45 modeled after the flow path 7 is cut out in the FPC 44 in a region that crosses the first conductive region 41 and the second conductive region 42 formed on the front surface 40a and the back surface 40b of the thin plate 40. By this cutout, the first electrode 10 and the second electrode 11, as well as the first dummy electrode 15 and the second dummy electrode 16, are simultaneously formed on both sides of the pattern 45 on the front surface 4a and the back surface 4b of the base 4. Since the first electrode 10 and the second electrode 11 facing the pattern 45 are formed simultaneously with the formation of the pattern 45, highly accurate alignment of the first electrode 10 and the second electrode 11 with respect to the flow path 7 is not required.

[0041] According to this manufacturing method, the electrodes 10 and 11 can be formed simultaneously with the formation of the flow channel 7, thereby reducing the number of manufacturing steps. By reducing the number of manufacturing steps, the manufacturing efficiency of the flow channel device 1 can be improved. As a result, the flow channel device 1 can be easily mass-produced. Furthermore, since the flow channel device 1 uses the FPC 44, the flow channel device 1 can be manufactured more inexpensively than when manufactured using glass or the like. Note that the first dummy electrode 15 and the second dummy electrode 16 do not necessarily have to be formed. In other words, the electrodes 10 and 11 may be formed by cutting out the pattern 45 along the edges of the first conductive region 41 and the second conductive region 42.

[0042] Fig. 10 is a plan view schematically showing the structure of a flow channel device 1A according to a second embodiment of the present invention. Fig. 11 is an end view of a cross section taken along line 11-11 in Fig. 10. Unlike the flow channel device 1 according to the first embodiment, this flow channel device 1A is a device for aligning (focusing) specific particles such as cells using dielectrophoresis.

[0043] 10 and 11 , the flow path device 1A according to the second embodiment has a laminated structure of a first covering member 2, a first cover 3, a base 4, a second cover 5, and a second covering member 6, similar to the flow path device 1 according to the first embodiment. This flow path device 1A has a flow path 7A having a shape different from the flow path 7 of the above-described flow path device 1, and further has a third electrode 17 and a fourth electrode 18 instead of the first dummy electrode 15 and the second dummy electrode 16 of the above-described flow path device 1. Otherwise, the same components as those of the flow path device 1 according to the first embodiment are denoted by the same reference numerals, and redundant description will be omitted here.

[0044] The flow path 7A has a third flow path portion 75 that extends linearly along the front surface 1a and back surface 1b of the flow path device 1. A flow path inlet 73 is formed at one end of the third flow path portion 75, and a flow path outlet 74 is formed at the other end of the third flow path portion 75. In this example, the flow path 7A also extends along the long side surfaces 1d and 1e of the flow path device 1. The flow path 7A is similar to the structure of the flow path device 1 according to the first embodiment in that it is formed to penetrate the base 4, the first cover 3, and the second cover 5, i.e., the FPC, from the front surface to the back surface, that the upper and lower surfaces of the flow path 7A are closed by the first covering member 2 and the second covering member 5, respectively, and that the flow path inlet 73 and the flow path outlet 74 are formed in the first covering member 2.

[0045] The third electrode 17 is formed on the front surface 4a of the base 4 and faces the first electrode 10 across the flow path 7A. The fourth electrode 18 is formed on the back surface 4b of the base 4 and faces the second electrode 11 across the flow path 7A. The third electrode 17 and the fourth electrode 18 are disposed opposite each other in the thickness direction of the base 4. The third electrode 17 and the fourth electrode 18 face the other side surface 7b of the flow path 7. The third electrode 17 and the fourth electrode 18 also face the flow path 7A at the same length in the longitudinal direction of the flow path 7A. Similarly, the third electrode 17 and the fourth electrode 18 also face the flow path 7A at the same length in the longitudinal direction of the flow path 7A as the first electrode 10 and the second electrode 11.

[0046] In the second embodiment, the first conductive pad 8 is electrically connected to the second electrode 11 and the third electrode 17 via the first conductive pattern 12. To electrically connect the first conductive pad 8 and the second electrode 11, the first conductive pattern 12 extends between the front surface 4 a and the back surface 4 b of the base 4 via a through-hole via 19. On the other hand, the second conductive pad 9 is electrically connected to the first electrode 10 and the fourth electrode 18 via the second conductive pattern 13. To electrically connect the second conductive pad 9 and the fourth electrode 18, the second conductive pattern 13 extends between the front surface 4 a and the back surface 4 b of the base 4 via a through-hole via 20. In this example, the second electrode 11 and the third electrode 17 are electrodes to which a voltage is applied, and the first electrode 10 and the fourth electrode 18 are electrodes to which a voltage is applied.

[0047] FIG. 12 is a partially enlarged cross-sectional view of the flow channel device 1A, schematically illustrating the electric field formed in the flow channel 7A. In the flow channel device 1A, a solution and a substance C, e.g., multiple types of cells or other microparticles having a dielectric constant smaller than that of the solution, are suspended in the sample solution. When a predetermined voltage is applied between the first electrode 10 and the second electrode 11 and between the third electrode 17 and the fourth electrode 18, an electric field is formed in the flow channel 7A. In this flow channel device 1A, electric fields E1 and E2 are formed along the thickness direction of the flow channel 7A, crossing the flow channel 7A. Specifically, an electric field E1 is formed between the first electrode 10 and the second electrode 11 on the side surface 7a of the flow channel 7A, and an electric field E2 is formed between the third electrode 17 and the fourth electrode 18 on the side surface 7b.

[0048] In this case, the inventors conducted a simulation using finite element analysis (FEM) software and confirmed that these electric fields E1 and E2 exert a repulsive force F1 (negative dielectrophoresis) not only toward the center of the flow channel 7A in the width direction (a direction parallel to the front surface 1a and back surface 1b and perpendicular to the length direction of the flow channel 7A) but also toward the center of the thickness direction (a direction perpendicular to the front surface 1a and back surface 1b) of the flow channel 7A. That is, in the flow channel 7A, the substance C is subjected to the repulsive force F1 so as to move toward the center in both the thickness direction and the width direction of the flow channel 7A. As a result, the substance C is aligned at the center of the thickness direction and the width direction of the flow channel 7A. In this manner, focusing is performed in the flow channel device 1A. The flow channel device 1A is manufactured using the same manufacturing method as the flow channel device 1. A redundant description will be omitted here.

[0049] 13 is a plan view schematically showing the structure of a flow path device 1B according to a third embodiment of the present invention. The flow path device 1B according to the third embodiment has a structure that combines the flow path device 1 according to the first embodiment and the flow path device 1A according to the second embodiment. The flow path device 1B has the flow path 7 of the flow path device 1 according to the first embodiment. The configuration of the flow path device 1A is established on the flow path inlet 73 side of the flow path 7, and the configuration of the flow path device 1 is established on the flow path outlet 74 side. In other words, the configuration of the flow path device 1A and the configuration of the flow path device 1 are arranged along the flow path 7. Other components that are similar to those of the flow path device 1 according to the first embodiment and the flow path device 1A according to the second embodiment are denoted by the same reference numerals, and redundant description will be omitted here.

[0050] In the flow path device 1B, the first electrode 10, the second electrode 11, the third electrode 17, and the fourth electrode 18 of the flow path device 1A are arranged adjacent to the flow path 7 on the upstream side of the first flow path portion 71. Furthermore, the first electrode 10, the second electrode 11, the first dummy electrode 15, and the second dummy electrode 16 of the flow path device 1 are arranged adjacent to the flow path 7 on the downstream side of the first flow path portion 71. Note that although the pattern shapes of the first conductive pattern 12 and the second conductive pattern 13 shown in FIG. 13 are different from those of the first and second embodiments, the electrical connection relationship is similar to that of the first and second embodiments. Note that the flow path device 1B is manufactured by the same manufacturing method as the flow path device 1. Duplicate explanations will be omitted here.

[0051] In this flow path device 1B, a sample solution prepared so that substances such as microparticles (e.g., cells) and solutions have the same dielectric constant as described above is flowed through the flow path 7. Furthermore, voltages with the same frequency and voltage value as described above are applied between the electrodes in the flow path device 1A region and the flow path device 1 region. As a result, substances that pass through the flow path device 1A region upstream of the flow path 7 are aligned (focused) to the center in the thickness and width directions of the flow path 7. When the substances aligned at the center of the flow path 7 pass through the flow path device 1 region downstream of the flow path 7, they are separated (sorted) by moving to the side 7a and side 7b of the flow path 7 based on the difference in dielectric constant. The separated substances are extracted from the flow path outlet 74 via the respective second flow path portions 72.

[0052] In this flow path device 1B, substances that have passed through the region of the flow path device 1A are aligned at the center of the thickness and width directions of the flow path 7 due to a repulsive force (negative dielectrophoresis) generated by the electric field between the electrodes of the flow path device 1A. When the aligned substances pass through the region of the flow path device 1, attractive forces (positive dielectrophoresis) and repulsive forces (negative dielectrophoresis) can act uniformly on the substances in the region of the flow path device 1. As a result, after passing through the region of the flow path device 1, one substance is separated from the other substance. Because attractive and repulsive forces act uniformly on the aligned substances, the accuracy of separating substances in the region of the flow path device 1 can be significantly improved.

[0053] In the above-described flow channel devices 1, 1A, and 1B, the first electrode 10, the second electrode 11, the third electrode 17, and the fourth electrode 18 face the side surface 7a or the side surface 7b of the flow channel 7 or 7A. However, as long as an electric field required for dielectrophoretic action can be formed in the flow channel 7 or 7A, the first electrode 10, the second electrode 11, the third electrode 17, and the fourth electrode 18 may be disposed at a position recessed from the side surface 7a or the side surface 7b of the flow channel 7 or 7A along the front surface 4a or the back surface 4b of the base 4. In other words, the first electrode 10, the second electrode 11, the third electrode 17, and the fourth electrode 18 may face the side surface 7a or the side surface 7b of the flow channel 7 or 7A at a predetermined distance.

[0054] Although the present invention has been described above through the above embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0055] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shapes, sizes, and the like, are not limited to those exemplified and may be modified as appropriate.

[0056] For example, the present invention includes differences that occur during implementation, such as manufacturing tolerances. Furthermore, within the scope of technical inconsistencies, components shown in different embodiments can be partially substituted or combined. Furthermore, each configuration can be appropriately and selectively combined to achieve at least some of the above-described problems and effects.

[0057] 1, 1A, 1B Flow path device, 1a First surface (surface), 1b Second surface (back surface), 1c Notch, 1d Side, 1e Side, 2 First covering member, 3 First cover, 4 Base, 4a Front surface, 4b Back surface, 40 Thin plate, 40a Front surface, 40b Back surface, 41 First conductive region, 42 Second conductive region, 43 Through-hole via, 44 Flexible printed circuit board, 45 Pattern, 5 Second cover, 6 Second covering member, 7, 7A Flow path, 7a Side, 7b Side, 71 First flow path portion, 72 Second flow path portion, 73 Flow path inlet, 74 Flow path outlet, 75 Third flow path portion, 8 First conductive pad, 9 Second conductive pad, 10 First electrode, 11 Second electrode, 12 First conductive pattern, 13 Second conductive pattern, 14 Through-hole via, 15 First dummy electrode, 16 Second dummy electrode, 17 Third electrode, 18 Fourth electrode, C, C1, C2 Substance, E, E1, E2 Electric field, F1 Repulsion force (negative dielectrophoresis), F2 Attraction force (positive dielectrophoresis)

Claims

1. A flow path device comprising: a base having a first surface and a second surface facing away from each other; and a pair of first and second electrodes, wherein the base has a flow path extending along the first and second surfaces, and the pair of first and second electrodes form an electric field that intersects the flow path along the direction in which the first and second surfaces face away from each other.

2. A flow path device according to claim 1, wherein the first electrode extends along the flow path on the side of the first surface, and the second electrode extends along the flow path on the side of the second surface.

3. The flow path device according to claim 2, wherein the first electrode is formed on the first surface and faces the flow path, and the second electrode is formed on the second surface and faces the flow path.

4. A flow path device as described in claim 3, comprising: a third electrode formed on the first surface and facing the flow path while facing the first electrode across the flow path; and a fourth electrode formed on the second surface and facing the flow path while facing the second electrode across the flow path.

5. A flow path device as described in claim 1, comprising: a first covering member provided on the first surface so as to cover the flow path; and a second covering member provided on the second surface so as to cover the flow path.

6. The flow path device according to claim 1, wherein the flow path has a first flow path portion that extends linearly.

7. The flow path device according to claim 1, wherein the flow path has a first flow path portion extending linearly and a pair of second flow path portions branching off from the first flow path portion.

8. The flow path device according to claim 1, wherein the flow path is exposed at each of the first surface and the second surface of the base.

9. The flow path device according to any one of claims 1 to 8, wherein the base, the pair of first electrodes and the second electrode form a flexible printed circuit board.

10. A method for manufacturing a flow path device, comprising the steps of: forming a first conductive region on a first surface of a base having a first surface and a second surface facing each other; forming a second conductive region on the second surface at a position corresponding to the first conductive region; and cutting out a flow path in the base in the first conductive region and the second conductive region, wherein by cutting out the flow path, a first electrode facing the flow path is formed on the first surface of the base, and a second electrode facing the flow path is formed on the second surface.

11. A method for manufacturing a flow path device as described in claim 10, wherein by cutting out the flow path, a third electrode facing the flow path and opposing the first electrode across the flow path is formed on the first surface of the base, and a fourth electrode facing the flow path and opposing the second electrode across the flow path is formed on the second surface of the base.

12. The method for manufacturing a flow channel device according to claim 10 or 11, wherein the flow channel is cut out by irradiating with laser light.

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