Fluid device

Abstract

To provide a fluid device having high fine particle trapping efficiency using ultrasound.SOLUTION: A fluid device separates fine particles in a fluid using an ultrasonic element. The fluid device comprises: an inflow passage through which the fluid flows; a separation section into which the fluid enters from the inflow passage and in which standing waves are formed by ultrasound transmitted from the ultrasonic element; a first outflow passage through which the fluid flows out from the separation section; and a second outflow passage through which the fluid also flows out from the separation section. The inflow passage is connected to one end of the separation section, the first outflow passage is connected to the other end opposite to the one end of the separation section so as to face the inflow passage, and the second outflow passage is connected at the other end of the separation section to a position different from that of the first outflow passage in a first direction intersecting a flow direction of the fluid. At the separation section, an acoustic path length adjustment section with an inclined surface that is inclined from the inflow passage toward the second outflow passage, which equalizes acoustic path lengths for the standing waves.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fluidic device. [Background technology]

[0002] Fluidic devices that acoustically focus particles in a fluid are known. For example, a fluidic device disclosed in Non-Patent Document 1 transmits ultrasonic waves from an ultrasonic element into a flow channel to form a standing wave. In this fluidic device, a fluid is introduced from an inlet flow channel into a separation section whose flow channel width is wider than that of the inlet flow channel, and an ultrasonic element generates a standing wave along the width of the separation section. As a result, particles in the fluid flowing through the separation section are captured at the node of the standing wave due to the pressure gradient of the standing wave. In addition, on the opposite side (downstream side) of the separation section from the inlet flow channel, a first outlet flow channel facing the inlet flow channel and a second outlet flow channel positioned widthwise from the first outlet flow channel are connected. As a result, a concentrated fluid with a high concentration of particles flows out from the first outlet flow channel, and a diluted fluid with a low concentration of particles flows out from the second outlet flow channel. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] E. Benes, 9 others, “THE ULTRASONIC h-SHAPE SEPARATOR: HARVESTINGOF THE ALGA SPIRULINA PLATENSIS UNDER ZERO-GRAVITY CONDITIONS”, WCU 2003, Paris, september 7-10, 2003, p1631-1638 Summary of the Invention [Problem to be solved by the invention]

[0004] In the fluidic device described in Patent Document 1, the fluid flows from an inlet channel with a constant width into a separation section with a large width abruptly, which poses a problem that turbulence is likely to occur in the separation section, reducing the efficiency of capturing particles by standing waves. [Means for solving the problem]

[0005] A fluidic device according to a first aspect of the present disclosure is a fluidic device that separates fine particles in a fluid using an ultrasonic element, and is equipped with an inlet flow path through which a fluid flows, a separation section into which the fluid flows from the inlet flow path and into which a standing wave is formed by the ultrasonic element, a first outlet flow path through which the fluid flows out of the separation section, and a second outlet flow path through which the fluid flows out of the separation section, wherein the inlet flow path is connected to one end side of the separation section, the first outlet flow path is connected to the other end side of the separation section opposite the one end side and facing the inlet flow path, and the second outlet flow path is connected to the other end side of the separation section at a position different from the first outflow flow path in a first direction intersecting the flow direction of the fluid, and the separation section has an inclined surface that slopes from the inlet flow path toward the second outflow flow path, and is equipped with an acoustic path length adjustment section that aligns the acoustic path length of the standing wave. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating a fluidic device according to an embodiment of the present disclosure. [Figure 2] 5A and 5B are schematic diagrams showing the shape of a separation section having a sound path length adjustment section according to the present embodiment. [Figure 3] 5A and 5B are schematic diagrams showing another example of a separation unit having a sound path length adjustment unit according to the present embodiment. [Figure 4] FIG. 1 is a schematic diagram showing a fluid flow in a conventional fluidic device. [Figure 5] FIG. 2 is a schematic diagram showing the flow of a fluid in the fluidic device of the present embodiment. [Figure 6] 3A and 3B are schematic diagrams showing the sound pressure distribution of ultrasonic waves in the fluidic device of the present embodiment. [Figure 7]10 is a schematic diagram showing the sound pressure distribution of ultrasound in a fluid device without a sound path length adjustment unit. [Figure 8] FIG. 10 is a cross-sectional view showing a modified example of the fluidic device of the present embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing a modified example of the fluidic device of the present embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a modified example of the fluidic device of the present embodiment. [Figure 11] 11 is a schematic diagram showing the sound pressure distribution of ultrasonic waves in the fluidic device of FIG. 10. DETAILED DESCRIPTION OF THE INVENTION

[0007] A fluidic device according to an embodiment of the present disclosure will now be described. [Configuration of fluidic devices] Fig. 1 is a cross-sectional view that schematically shows a fluidic device 10 of this embodiment. Fig. 2 is a schematic diagram that shows the shape of a separation section 30 of this embodiment. As shown in FIG. 1, the fluidic device 10 includes an inlet flow channel 20, a separation section 30, a first outlet flow channel 40, a second outlet flow channel 50, an ultrasonic element 60, and an acoustic path length adjustment section 70. In the fluidic device 10, a fluid containing fine particles flows from the inlet flow channel 20 into the separation section 30. A portion of the fluid that flows into the separation section 30 flows out through the first outlet flow channel 40, and the other portion flows out through the second outlet flow channel 50. In this embodiment, the inflow direction of the fluid from the inflow channel 20 into the separation unit 30 is defined as the X direction. In the separation unit 30, one end where the inflow channel 20 is located is the -X side in the X direction, and the other end where the first outflow channel 40 and the second outflow channel 50 are located is the +X side in the X direction. In addition, the up-down direction of the paper in FIG. 1 is the Z direction that intersects (is perpendicular to) the X direction, with the upper side of the paper being the +Z side and the lower side of the paper being the -Z side.

[0008] In this embodiment, the ultrasonic element 60 is installed at the +Z side end of the separation unit 30, and the sound path length adjustment unit 70 is installed at the −Z side end of the separation unit 30. When ultrasonic waves are transmitted from the ultrasonic element 60 to the separation unit 30 in the Z direction, the transmitted ultrasonic waves are reflected by the reflecting surface 71 of the sound path length adjustment unit 70, and a standing wave SW is formed in the separation unit 30. Specifically, ultrasonic waves of wavelength λ are transmitted from the ultrasonic element 60, and the transmission frequency of the ultrasonic element 60 is adjusted so that an integer multiple of half the wavelength λ / 2 matches the sound path length from the ultrasonic element 60 to the reflecting surface 71 of the sound path length adjustment unit 70, thereby forming a standing wave SW in the fluid in the separation unit 30 (the space between the surface of the ultrasonic element 60 and the inclined surface 73 of the sound path length adjustment unit 70). In FIG. 1, the standing wave SW is represented by a plurality of horizontal lines (lines parallel to the X direction), and these horizontal lines indicate examples of the positions of the nodes of the standing wave SW.

[0009] The standing wave SW formed in the separation unit 30 has multiple nodes, and traps particles in the fluid at the node positions. The fluid that flows in from the inflow channel 20 connected to the -X side and the +Z side of the separation unit 30 is trapped at the node positions of the standing wave SW on the +Z side of the standing wave SW, and flows along the flow of the fluid to the first outflow channel 40 provided on the +X side and the +Z side. At this time, the particles in the fluid are captured at the node of the standing wave SW on the +Z side, and are therefore prevented from moving toward the -Z side. Therefore, a concentrated fluid with a high concentration of particles flows out from the first outlet flow path 40 provided on the +Z side of the separation unit 30, and a diluted fluid with a low concentration of particles flows out from the second outlet flow path 50 provided on the -Z side.

[0010] In this embodiment, the ultrasonic element 60 is provided at the +Z side end of the separation unit 30. The ultrasonic element 60 may have any configuration as long as it generates a standing wave SW in the Z direction of the separation unit 30. For example, the ultrasonic element 60 may be a bulk-type ultrasonic element that transmits ultrasonic waves by applying a voltage to a piezoelectric body, thereby vibrating the piezoelectric body itself. In this case, the position of the ultrasonic element 60 is not particularly limited as long as ultrasonic waves can propagate to the separation unit 30, and the ultrasonic element 60 can be placed at any position in the fluidic device 10. For example, the ultrasonic element 60 may be provided on the +Z side or -Z side of the separation unit 30. The direction perpendicular to the X direction and the Z direction is defined as the Y direction, and the ultrasonic element 60 may be provided on the +Y side or -Y side of the separation unit 30. Alternatively, the ultrasonic element 60 may be provided at a position away from the separation unit 30. Alternatively, a thin-film ultrasonic element may be used as the ultrasonic element 60, in which a plurality of ultrasonic transducers, each having a piezoelectric element disposed in a thin-film vibration portion, are arranged in an array, and ultrasonic waves are transmitted by vibrating each vibration portion when a voltage is applied to the piezoelectric element. When such a thin-film ultrasonic element is used as the ultrasonic element 60, it is possible to make the element smaller and thinner than when a bulk ultrasonic element is used, which can facilitate miniaturization of the fluidic device 10.

[0011] [Configuration of sound path length adjustment unit 70] In this embodiment, a sound path length adjusting section 70 is provided at the −Z side end of the separating section 30. The sound path length adjusting section 70 has a reflecting surface 71 , a guide member 72 , and an inclined surface 73 . The reflecting surface 71 is formed on the wall surface of the −Z side end of a cavity formed in the fluidic device 10 to serve as the separation section 30, and is a flat surface inclined with respect to the X direction so that the +X side transitions to the −Z side. The +X side end of the reflecting surface 71 is continuous with the −Z side inner wall surface of the second outflow channel 50. The guide member 72 is formed from a sound-transmitting resin material, and its surface on the −Z side is in close contact with the reflecting surface 71 . Inclined surface 73 is a flat surface formed on the surface of guide member 72 and inclined with respect to the X direction so that the +X side transitions to the -Z side. The -X side end of inclined surface 73 is continuous with the -Z side inner wall surface of inflow flow channel 20, and the +X side end of inclined surface 73 is continuous with the -Z side inner wall surface of second outflow flow channel 50 at the same position as the +X side end of reflecting surface 71.

[0012] The resin material forming the guide member 72 is preferably a material with a sound speed significantly different from that of the flowing fluid and an acoustic impedance similar to that of the flowing fluid. Examples of such materials include silicone-based materials used in the matching layer of ultrasonic probes. The guide member 72 can be integrally fabricated by insert molding, overmolding, or the like when fabricating the fluidic device 10 by injection molding, cutting, 3D printing, or the like. On the other hand, it is preferable to select a material for the reflecting surface 71 that has a significantly different acoustic impedance from the resin material of the guide member 72 .

[0013] In this embodiment, the resin material forming the guide member 72 is a material in which the speed of sound inside the material is slower than the speed of sound of the fluid flowing into the separation section 30 . Ultrasonic waves in the Z direction transmitted from the ultrasonic element 60 travel through the separation unit 30 to the -Z side and enter the inside of the guide member 72 from the inclined surface 73. The incident ultrasonic waves are refracted based on the difference in the speed of sound in the medium, and the direction of travel of the ultrasonic waves traveling inside the guide member 72 is deflected toward the -X side with respect to the Z direction. If the ultrasonic waves traveling inside the guide member 72 are incident in a direction perpendicular to the reflecting surface 71, they are reflected and travel toward the +Z side along their original path, and a standing wave SW can be formed in the separation unit 30.

[0014] 2, the maximum flow path width W1 of the separation section 30, the length A of the separation section 30 in the X direction, the flow path width W01 of the inflow flow path 20, the sound speed C1 of the fluid flowing into the separation section 30, the sound speed C2 (C1 <C2)とする。 If the inclination angle of the reflecting surface 71 with respect to the X-axis direction is α and the inclination angle of the inclined surface 73 is β, then according to Snell's law, the angle of incidence (β) and angle of refraction γ (γ=β-α) of the sound wave are as follows: C1·sin(β-α)=C2·sinβ At a position a distance P from the +X side end of the separation unit 30 to the -X side, the sound path length of the ultrasonic wave from the ultrasonic element 60 to the inclined surface 73 is Lx1, the sound path length of the ultrasonic wave from the inclined surface 73 to the reflecting surface 71 is Lx2, and the sound path length of the ultrasonic wave refracted at the inclined surface 73 from the ultrasonic element 60 to the reflecting surface 71 is Lx, as follows: Lx1=W1―P·tanβ Lx2=(C1 / C2)·(P / cosβ)·sin(β-α) Lx=Lx1+Lx2 =W1―P·tanβ+(P / cosβ)·(C1 / C2)·sin(β-α) =W1 Therefore, the sound path length Lx of the ultrasonic wave that passes from the ultrasonic element 60 through the separation section 30, refracts at the inclined surface 73, and reaches the reflecting surface 71 is a constant sound path length Lx (= W1) at any position in the X direction of the separation section 30, and a standing wave SW can be formed by adjusting the frequency of the ultrasonic wave from the ultrasonic element 60.

[0015] The resin material forming the guide member 72 may be a material in which the speed of sound inside the material is faster than the speed of sound of the fluid flowing into the separation section 30 (C1>C2). 3, the maximum flow path width W1 of separation section 30, the length A of separation section 30 in the X direction, the flow path width W01 of inflow flow path 20, the sound speed C1 of the fluid flowing into separation section 30, the sound speed C2 in the material of guide member 72, and the sound path lengths Lx1, Lx2, and Lx are the same as those explained in Fig. 2. However, because the sound speed of the fluid is C1>C2, the inclination angle α of reflecting surface 71 becomes negative, and reflecting surface 71 is inclined so that it deviates toward the -Z side as it approaches the -X side.

[0016] [Fluid flow in the fluidic device 10] FIG. 4 is a schematic diagram showing the flow of fluid flowing through a separation section 30R in a conventional fluidic device 10R. 4, inlet flow path 20 is connected to separation unit 30R on the -X side, a first outlet flow path 40 that allows concentrated fluid to flow is connected to the +X side opposite inlet flow path 20, and a second outlet flow path 50 is connected to the -Z side of first outlet flow path 40. Separation unit 30R has wall surfaces whose +Z side end and -Z side end are each continuous in the X direction. The example shown in FIG. 4 is a simulation result in which a fluid is introduced from the inflow channel 20 at a flow rate of 5 mL / min. As shown in FIG. 4, the fluid that flows into the separation unit 30R generates turbulence in the separation unit 30R. That is, not only does the flow velocity component toward the -Z side increase, but a flow velocity component that tries to return to the inflow channel 20 side also occurs. Turbulence is also generated when the fluid with the flow velocity component toward the inflow channel 20 collides with the fluid flowing in from the inflow channel 20. In this conventional separation unit 30R, a vortex U1 is generated on the +Z side of the separation unit 30R. As a result, even if a standing wave SW is formed in the separation unit 30R, particles in the fluid trapped at the nodes of the standing wave SW may deviate from the pressure gradient of the ultrasonic waves, resulting in a decrease in the amount of particles flowing into the first outflow channel 40.

[0017] 5 is a schematic diagram showing the flow of fluid flowing through the separation section 30 in the fluidic device 10 of this embodiment. Fig. 5 shows the flow of fluid through the separation section 30 when the flow rate of the fluid is 5 (mL / min). In this embodiment, the -Z side of the separation section 30 is an inclined surface 73, and therefore the separation section 30 is tapered such that the cross-sectional area continuously increases from the -X side end to the +X side end, and the fluid flowing in from the inlet flow path 20 reaches the +X side end while maintaining laminar flow, and flows out into the first outlet flow path 40 or the second outlet flow path 50 without generating turbulence.

[0018] [Formation of standing wave SW in fluidic device 10] FIG. 6 is a schematic diagram showing the sound pressure distribution of the fluid in the separation unit 30 when ultrasonic waves are transmitted from the ultrasonic element 60 in the fluidic device 10 of this embodiment. In the fluidic device 10, when ultrasonic waves are transmitted from the ultrasonic element 60, the ultrasonic waves travel toward the -Z side through the fluid in the separation unit 30 and are incident on the inclined surface 73. The incident ultrasonic waves are refracted at the inclined surface 73, travel through the material of the guide member 72, and are incident at a right angle on the reflecting surface 71. The ultrasonic waves are reflected by the reflecting surface 71 and travel along the reverse path, returning from the inclined surface 73 to the separation unit 30 and to the ultrasonic element 60. In this embodiment, the length of the path that the ultrasonic waves follow (the above-described sound path length Lx in FIG. 2) is kept constant (Lx=W1) regardless of the position in the X direction by the sound path length adjustment unit 70. Therefore, the ultrasonic waves transmitted from the ultrasonic element 60 form standing waves SW in the guide member 72 of the sound path length adjustment unit 70 and the fluid in the separation unit 30, which are between the ultrasonic element 60 and the reflection surface 71.

[0019] In the fluidic device 10 of this embodiment, the sound path length is adjusted by the sound path length adjusting section 70, so that the inclined surface 73 rectifies the flow and creates a standing wave SW. In contrast to this, if the sound path length adjusting section 70 is not provided, the standing wave SW cannot be formed in the separating section 30.

[0020] FIG. 7 is a schematic diagram showing the sound pressure distribution of the fluid in a fluidic device 10Q that has an inclined surface 73 but does not have a guide member 72 or a reflecting surface 71 as a sound path length adjuster 70. In FIG. In the fluidic device 10Q, the ultrasonic waves transmitted from the ultrasonic element 60 cannot trace their original path even when reflected by the inclined surface 73, and therefore the desired standing wave SW cannot be formed.

[0021] [Effects of this embodiment] The fluidic device 10 of this embodiment includes an inflow channel 20 through which a fluid flows, a separation unit 30 into which the fluid flows from the inflow channel 20 and into which standing waves are formed by ultrasonic waves transmitted from an ultrasonic element, a first outflow channel 40 through which the fluid flows out of the separation unit, and a second outflow channel 50 through which the fluid flows out of the separation unit 30. The inflow channel 20 is connected to the −X side of the separation unit 30, the first outflow channel 40 is connected to the +X side of the separation unit 30 opposite the inflow channel 20, and the second outflow channel 50 is connected to the +X side of the separation unit 30 at a position different from the first outflow channel 40 in the Z direction. The −Z side end of the separation unit 30 is provided with an acoustic path length adjustment unit 70 having an inclined surface 73 inclined from the inflow channel 20 toward the second outflow channel 50 and adjusting the acoustic path length of the standing wave SW.

[0022] In this fluidic device 10, the fluid flowing from the inlet channel 20 into the separation unit 30 flows out from the separation unit 30 to the first outlet channel 40 and the second outlet channel 50. In the flow leading to the first outlet channel 40, the first outlet channel 40 faces the inlet channel 20, suppressing the generation of turbulence. In the flow leading to the second outlet channel 50, the flow from the inlet channel 20 is guided by the inclined surface 73 of the sound path length adjustment unit 70, suppressing the generation of turbulence. Here, the sound path length adjustment unit 70 aligns the acoustic path length of the ultrasonic waves, thereby forming a standing wave SW in the separation unit 30 even if the inclined surface 73 is located on the ultrasonic wave path. Therefore, particles captured at the node positions of the standing wave SW can flow into the first outlet channel 40 without being swept toward the inlet channel 20 or the second outlet channel 50 by the turbulent fluid flow, thereby suppressing a decrease in the ultrasonic wave capture efficiency.

[0023] In this embodiment, the sound path length adjusting section 70 is made of a material that transmits ultrasonic waves. This allows the sound path length adjusting section 70 to transmit the ultrasonic waves that form the standing wave SW, and allows the inclined surface 73 to be placed on the path of the standing wave SW.

[0024] In this embodiment, the reflecting surface 71 is perpendicular to the direction of travel of the ultrasonic waves that have passed through the inclined surface 73 and reflects the ultrasonic waves. As a result, ultrasonic waves transmitted through the inclined surface 73 are reflected by the reflecting surface 71, and a standing wave SW can be formed on the sound path of the ultrasonic waves, and the inclined surface 73 can be placed on the path of the standing wave SW.

[0025] In this embodiment, the ultrasonic element 60 is disposed on the flow path wall of the separation section 30 . This allows ultrasonic waves to be sent from the ultrasonic element 60 to the fluid flowing through the separation section 30, thereby forming a standing wave SW.

[0026] In this embodiment, the ultrasonic element 60 is disposed on the surface opposite to the inclined surface 73 of the sound path length adjustment section 70 . This allows the formation of a standing wave SW that travels from the ultrasonic element 60 through the inclined surface 73 and reaches the reflecting surface 71.

[0027] [Variations] The present invention is not limited to the above-described embodiment, and the present invention includes configurations obtained by modifications and improvements within the scope that can achieve the object of the present invention.

[0028] (Variation 1) In the above-described embodiment, the entire surface of the guide member 72 on the ultrasonic element 60 side is formed as the inclined surface 73, but a configuration in which only a portion is not the inclined surface 73 is also possible. 8, the fluidic device 10A has a sound path length adjustment unit 70A including a reflecting surface 71A, a guide member 72A, and an inclined surface 73A, and the -X side end of each extends toward the -X side. An extension surface 711 of the reflecting surface 71 and an extension surface 731 of the inclined surface 73 are each parallel to the X direction. In this fluidic device 10A, in the region of the inclined surface 73A, ultrasonic waves transmitted from the ultrasonic element 60 are reflected along a path similar to that in the above-described embodiment, forming a standing wave SW in the separation unit 30. Meanwhile, in the region of the extension surface 731 of the inclined surface 73A, ultrasonic waves transmitted from the ultrasonic element 60 are incident on the extension surface 731 at a right angle, pass through the extension portion 721 of the guide member 72A, are reflected by the extension surface 711 of the reflecting surface 71A, and return from the extension surface 731 to the ultrasonic element 60. The acoustic path length in this region is the same as that at the end on the -X side of the inclined surface 73A, and forms a constant standing wave SW in the X direction. Therefore, the desired standing wave SW can be formed in the separating section 30 also in the configuration of FIG.

[0029] (Variation 2) In the above-described embodiment, the ultrasonic element 60 is installed on the flow path wall on the +Z side of the separation unit 30, but the ultrasonic element 60 may also be installed on the −Z side of the sound path length adjustment unit . 9, the fluidic device 10B has a guide member 72 and an inclined surface 73 as a sound path length adjustment section 70B, and an ultrasonic element 60B is installed on the surface of the guide member 72 opposite the inclined surface 73. The surface of the guide member 72 opposite the inclined surface 73 is formed with the same inclination as the reflecting surface 71 (see FIG. 1) in the fluidic device 10 of the above-described embodiment, and the surface of the ultrasonic element 60B also has the same inclination angle. Meanwhile, in the fluidic device 10B, the wall surface on the +Z side of the separation section 30 is a reflecting surface 71B that reflects ultrasonic waves. In this fluidic device 10B, ultrasonic waves from the ultrasonic element 60B are emitted from the inclined surface 73 through the guide member 72, pass through the fluid flowing in the separation section 30, are reflected by the reflecting surface 71B, and travel the same path in the opposite direction, from the inclined surface 73 through the guide member 72, and return to the ultrasonic element 60B. The ultrasonic path is in the opposite direction to that of the fluidic device 10 described above, but the acoustic path length is the same, and therefore a standing wave SW similar to that of the fluidic device 10 can be formed.

[0030] (Variation 3) In the embodiment described above, a guide member 72 having a substantially triangular cross section is used as the sound path length adjustment unit 70, and a configuration is adopted in which the guide member 72 has inclined surfaces 73 and reflecting surfaces 71 on its front and back sides. However, the inclined surfaces 73 may be formed by a plate-like member instead of the guide member 72. In Figure 10, the fluidic device 10C has an inlet flow path 20, a separation section 30, a first outlet flow path 40, a second outlet flow path 50, and an ultrasonic element 60 similar to those of the previously described fluidic device 10, and also has a sound path length adjustment section 70C. The sound path length adjustment unit 70C has a reflecting surface 71C, a guide member 72C, and an inclined surface 73. The reflecting surface 71C is formed by the wall surface on the -Z side of a cavity formed in the fluidic device 10 to serve as the separation unit 30, and extends along the X direction. The guide member 72C is a plate member of a constant thickness made of a sound-transmitting resin material, and the surface on the +Z side is the inclined surface 73. The guide member 72C may be a plate-shaped acoustic metamaterial material having sound transparency. In fluidic device 10C, the cavity that will become separation section 30 is divided into a +Z side and a -Z side by guide member 72C. The compartment on the +Z side of guide member 72C becomes separation section 30, through which fluid flows from inflow channel 20. Space 74 on the -Z side of guide member 72C is connected to inflow channel 20 by connecting channel 75, and is filled with fluid introduced from inflow channel 20.

[0031] In such a fluidic device 10C, fluid flows from the inflow channel 20 into the separation section 30 and flows out from the separation section 30 into the first outflow channel 40 and the second outflow channel 50. At this time, the wall surface of the separation section 30 is continuous from the inflow channel 20 to the first outflow channel 40 on the +Z side, and is continuous from the inflow channel 20 to the second outflow channel 50 via the inclined surface 73 on the -Z side. Therefore, the fluid flowing through the separation section 30 maintains laminar flow and flows out into the first outflow channel 40 or the second outflow channel 50 without generating turbulence. Meanwhile, in the separation unit 30, ultrasonic waves transmitted from the ultrasonic element 60 travel through the fluid in the separation unit 30, reach the inclined surface 73 of the sound path length adjustment unit 70C, and then travel through the guide member 72C and the fluid in the space 74 to the reflecting surface 71C, where they are reflected and return to the ultrasonic element 60 along the original path. Here, in the sound path length adjustment unit 70C, the guide member 72C is disposed at an angle, but has a constant thickness from the -X side end to the +X side end of the separation unit 30, so that the ultrasonic waves entering the guide member 72C and the ultrasonic waves exiting the guide member 72C travel in the same direction. Therefore, the sound path length of the ultrasonic waves from the ultrasonic element 60 to the reflecting surface 71C is constant regardless of the position in the X direction. Therefore, by adjusting the ultrasonic element 60, a standing wave SW can be formed over the entire length of the separation unit 30 in the X direction.

[0032] FIG. 11 is a schematic diagram showing the sound pressure distribution of the fluid in the separation unit 30 when ultrasonic waves are transmitted from the ultrasonic element 60 in the fluidic device 10C. In the fluidic device 10C, the length of the path that the ultrasonic waves follow is constant (Lx=W1) regardless of the position in the X direction by the sound path length adjusting unit 70C. Therefore, the ultrasonic waves transmitted from the ultrasonic element 60 can form a standing wave SW in the fluid between the separating unit 30 and the reflecting surface 71C.

[0033] In this way, in the fluidic device 10C, the sound path length adjuster 70C uses the guide member 72C, which is a plate-like member, and the surface of the guide member 72C on the side where the inflow channel 20 is located can be used as the inclined surface 73. Furthermore, since there is provided a connecting flow path 75 that connects the inflow flow path 20 to the space 74 that contacts the surface of the sound path length adjustment unit 70C opposite to the inclined surface 73, the space 74 that contacts the surface of the guide member 72C opposite to the inclined surface 73 can be filled with the fluid that flows in from the inflow flow path 20. This allows the propagation direction of the ultrasonic waves that enter the inclined surface 73 to be the same as the propagation direction of the ultrasonic waves that exit from the surface on the opposite side.

[0034] In the fluidic device 10C, the connecting flow path 75 that connects the inflow flow path 20 and the space 74 is not limited to being formed inside the fluidic device 10C, but may be an external pipe or the like. The space 74 is not limited to being introduced with the fluid flowing through the inflow flow path 20, but may be a closed space filled with a fluid of the same quality as the fluid flowing through the separation section 30. The space 74 may be provided with a discharge flow path for discharging the fluid therein. In the fluidic device 10C, the fluid contained in the space 74 is not limited to being of the same quality as the fluid flowing through the separation unit 30, and may be a different type of fluid. In this case, the inclination angle of the reflection surface 71C or the acoustic characteristics of the fluid may be adjusted so that the sound path length of the ultrasonic waves from the ultrasonic element 60 to the reflection surface 71C is constant at any position in the X direction of the separation unit 30.

[0035] Summary of this disclosure A fluidic device according to a first aspect of the present disclosure is a fluidic device that separates particles in a fluid using ultrasound transmitted from an ultrasonic element, and comprises an inlet flow path through which a fluid flows, a separation section into which the fluid flows from the inlet flow path and into which a standing wave is formed by the ultrasonic element, a first outlet flow path through which the fluid flows out of the separation section, and a second outlet flow path through which the fluid flows out of the separation section, wherein the inlet flow path is connected to one end of the separation section, the first outlet flow path is connected to the other end of the separation section opposite the one end, facing the inlet flow path, and the second outlet flow path is connected to the other end of the separation section at a position different from the first outlet flow path in a first direction intersecting the flow direction of the fluid, and the separation section is provided with an inclined surface that slopes from the inlet flow path toward the second outlet flow path and that aligns the acoustic path length of the standing wave.

[0036] As a result, the fluid flowing into the separation section from the inlet flow path flows out of the separation section into the first outlet flow path and the second outlet flow path. In the flow leading to the first outlet flow path, the first outlet flow path faces the inlet flow path, suppressing the generation of turbulence. Furthermore, in the flow leading to the second outlet flow path, the flow from the inlet flow path is guided by the inclined surface of the acoustic path length adjustment section, suppressing the generation of turbulence. Here, the acoustic path length adjustment section aligns the acoustic path length of the standing wave, thereby enabling the formation of a standing wave in the separation section even if an inclined surface is present in the ultrasonic sound path. Therefore, particles captured at the node position of the standing wave can flow into the first outlet flow path where they were captured, without being swept toward the inlet flow path or the second outlet flow path by the turbulent fluid flow, thereby suppressing a decrease in the ultrasonic capture efficiency.

[0037] In the fluidic device of this aspect, the sound path length adjustment section is made of a material that transmits the ultrasonic waves. This allows the sound path length adjusting section to transmit ultrasonic waves that form standing waves, and allows the inclined surface to be placed on the path of the standing waves.

[0038] In the fluidic device of this aspect, the sound path length adjusting section has a reflecting surface that is perpendicular to the propagation direction of the ultrasonic waves that have passed through the inclined surface and that reflects the ultrasonic waves. This allows ultrasonic waves that have passed through the inclined surface to be reflected by the reflecting surface, forming a standing wave on the sound path of the ultrasonic waves, and allows the inclined surface to be positioned on the path of the standing wave.

[0039] In the fluidic device of this aspect, the sound path length adjustment section is formed of a plate-like member. This allows the surface of the plate-like member on the side where the inflow channel is located to be used as an inclined surface. If the space in contact with the surface of the plate-like member opposite the inclined surface is filled with a fluid of the same quality as the fluid flowing in from the inflow channel, the ultrasonic waves entering the inclined surface and the ultrasonic waves exiting from the opposite surface can travel in the same direction.

[0040] The fluidic device of this aspect further comprises a connecting flow path that connects the inflow flow path to a space that contacts the surface of the sound path length adjustment portion opposite the inclined surface. This allows the fluid flowing in from the inflow channel to fill the space in contact with the surface of the plate-like member opposite the inclined surface.

[0041] In the fluidic device of this aspect, the ultrasonic element is disposed on the flow path wall of the separation section. This allows ultrasonic waves to be transmitted from the ultrasonic element to the fluid flowing through the separation section, thereby forming standing waves.

[0042] In the fluidic device of this aspect, the ultrasonic element is disposed on the surface of the sound path length adjustment section opposite to the inclined surface. This allows the formation of a standing wave that passes from the ultrasonic element through the inclined surface and reaches the reflecting surface. [Explanation of symbols]

[0043] 10, 10A, 10B, 10C...fluidic device, 20...inlet flow path, 30...separation section, 40...first outlet flow path, 50...second outlet flow path, 60, 60B...ultrasonic element, 70, 70A, 70B, 70C...sound path length adjustment section, 71, 71B, 71C...reflecting surface, 711...extension surface, 72, 72C...guide member, 721...extension section, 73...inclined surface, 731...extension surface, 74...space, 75...connecting flow path, C1, C2...sound speed, Lx, Lx1, Lx2...sound path length, P...distance, SW...standing wave, U1...vortex, W01, W1...flow path width, α, β...inclination angle, γ...refraction angle.

Claims

1. A fluidic device that separates particles in a fluid using an ultrasonic element, an inlet flow path through which a fluid flows; a separation section into which the fluid flows from the inflow channel and into which a standing wave is formed by ultrasonic waves transmitted from the ultrasonic element; a first outlet flow path through which the fluid flows out from the separation portion; a second outlet flow path through which the fluid flows out from the separation section, the inflow channel is connected to one end side of the separation section, the first outlet flow path is connected to the other end side of the separation section opposite to the one end side thereof so as to face the inlet flow path; the second outlet flow path is connected to the other end side of the separation section at a position different from the first outlet flow path in a first direction intersecting a flow direction of the fluid, A fluidic device characterized in that the separation section has an inclined surface that slopes from the inlet flow path toward the second outlet flow path, and is provided with an acoustic path length adjustment section that aligns the acoustic path length of the standing wave.

2. The sound path length adjusting section is made of a material that transmits the ultrasonic waves. The fluidic device according to claim 1 .

3. The sound path length adjusting section has a reflecting surface that is perpendicular to the direction of travel of the ultrasonic waves that have passed through the inclined surface and that reflects the ultrasonic waves. The fluidic device according to claim 2 .

4. The sound path length adjusting section is formed of a plate-like member. The fluidic device according to claim 2 .

5. Further, a connecting flow path is provided that connects the inflow flow path to a space that contacts the surface of the sound path length adjustment portion opposite to the inclined surface. The fluidic device according to claim 4 .

6. The ultrasonic element is disposed on a flow path wall of the separation section. The fluidic device according to claim 1 .

7. The ultrasonic element is disposed on the surface of the sound path length adjustment part opposite to the inclined surface. The fluidic device according to claim 1 .

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