Fluid device

Abstract

To provide a fluid device having high capture efficiency of fine particles by ultrasonic waves.SOLUTION: A fluid device for separating fine particles in fluid using ultrasonic waves includes an inflow passage for allowing the fluid to flow therein, a separation part for allowing the fluid to flow from the inflow passage therein, and forming stationary waves in a first direction by the ultrasonic waves, a first outflow passage for allowing the fluid to flow from the separation part, and a second outflow passage for allowing the fluid to flow from the separation part, wherein the inflow passage is connected to one end side of the separation part, the first outflow passage is connected to the other end side opposite to the one end side of the separation part so as to face the inflow passage, the second outflow passage is connected to a position different from the first outflow passage in the first direction, on the other end side of the separation part, and the inflow passage becomes large in passage diameter as approaching the separation part.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 fixed width into a separation section with a large width abruptly, which causes turbulence in the separation section, which reduces 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 microparticles in a fluid using ultrasound, 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 along a first direction by the ultrasound, 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 the first direction, and the inlet flow path has a flow path diameter that increases as it approaches the separation section. [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] FIG. 4 is an enlarged cross-sectional view of a separation portion of the embodiment. [Figure 3] FIG. 10 is a schematic diagram showing the flow of fluid flowing through a separation unit of a conventional fluidic device. [Figure 4] FIG. 3 is a schematic diagram showing the flow of fluid flowing through a separation section of the fluidic device of the present embodiment. [Figure 5] FIG. 4 is a schematic diagram showing the tapered shape of an inflow channel according to the present embodiment. [Figure 6] 5A and 5B are schematic diagrams showing other examples of the tapered shape of the inflow channel of the present embodiment. [Figure 7] 10 is a schematic diagram showing the flow of fluid flowing through a separation section of a fluidic device according to Modification 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] A fluidic device according to an embodiment of the present disclosure will now be described. (Configuration of fluidic device) Fig. 1 is a cross-sectional view schematically showing a fluidic device 10 of this embodiment. Fig. 2 is an enlarged cross-sectional view of a separation section 30 of this embodiment. As shown in FIG. 1, the fluidic device 10 includes an inflow channel 20, a separation section 30, a first outflow channel 40, a second outflow channel 50, and an ultrasonic element 60. In the fluidic device 10 of this embodiment, a fluid containing fine particles flows from the inflow channel 20 to the separation section 30. Here, the inflow direction in which the fluid flows from the inflow channel 20 to the separation section 30 is referred to as the X direction. The X direction is the second direction of the present disclosure. One end side of the separation unit 30 is on the −X side in the X direction, and the other end side of the separation unit 30 is on the +X side in the X direction. 1, the up-down direction on the paper surface is the Z direction that intersects (is perpendicular to) the X direction, and is the first direction of the present disclosure. In this embodiment, as shown in FIG. 1, a standing wave SW is formed in the Z direction by ultrasonic waves being reflected between flat surface 31 on the -Z side of separation unit 30 and flat surface 32 on the +Z side. Note that in FIG. 1, the standing wave SW is represented by multiple horizontal lines (lines parallel to the X direction), and these horizontal lines indicate examples of node positions of the standing wave SW.

[0008] The inflow channel 20 is connected to the −X side, which is one end side of the separation section 30, and allows the fluid to flow in toward the +X side. The inflow channel 20 is tapered so that its channel diameter (channel width) increases toward the separation section 30, suppressing the generation of turbulence in the separation section 30. That is, an inlet pipe (not shown) that introduces fluid into the fluidic device 10 is connected to the −X side end of the inflow channel 20. Therefore, the channel diameter at the −X side end of the inflow channel 20 is formed to be approximately the same as the channel diameter D1 of the inlet pipe, e.g., 3 mm to 4 mm. Meanwhile, in the separation section 30, particles are captured at the node positions of the standing wave SW. Therefore, the flat surfaces 31 and 32 are set at a predetermined distance so that the standing wave SW can be formed, and the distance between the flat surfaces 31 and 32 is greater than that of the inflow channel 20. In such a fluidic device 10, it is necessary to suppress the flow of fluid that resists the pressure gradient of the ultrasound in the separation section 30, i.e., turbulence in the separation section 30. For this reason, inflow channel 20 of this embodiment is formed in a tapered shape so that the channel diameter increases toward separation unit 30, and channel diameter D2 at the +X side opening end of inflow channel 20 is larger than channel diameter D1 at the -X side opening end. This reduces the flow rate of the fluid flowing into separation unit 30 while maintaining laminar flow by enlarging the channel diameter. The tapered shape of the inflow channel 20 will be described in detail later.

[0009] The separation section 30 separates fine particles from the fluid flowing in from the inlet flow path 20, and flows a concentrated fluid containing a large amount of the separated fluid into the first outlet flow path 40, and flows a diluted fluid from which the fine particles have been separated into the second outlet flow path 50. Specifically, as described above, inlet flow channel 20 is connected to the −X side and the +Z side of separation unit 30. Furthermore, a first outlet flow channel 40 is connected to the +X side and the +Z side of separation unit 30, that is, at a position facing inlet flow channel 20. Furthermore, a second outlet flow channel 50 is connected to the +X side and the −Z side of separation unit 30.

[0010] The separation unit 30 is provided with an ultrasonic element 60 that generates a standing wave SW in the fluid. 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 may 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.

[0011] Alternatively, the ultrasonic element 60 may be a thin-film ultrasonic element, 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 applying a voltage to the piezoelectric element to vibrate each vibration portion. When such a thin-film ultrasonic element is used, the ultrasonic element 60 is provided on at least one of the ±Z side surfaces (flat surfaces 31, 32) of the separation unit 30. The ultrasonic transmission surface of the ultrasonic element 60 may be configured to be in close contact with the flat surfaces 31, 32 of the separation unit 30, and the ultrasonic transmission surface may constitute at least one of the flat surfaces 31, 32 of the separation unit 30. When such a thin-film ultrasonic element is used as the ultrasonic element 60, it is possible to make the ultrasonic element 60 smaller and thinner than when a bulk ultrasonic element is used, which can facilitate miniaturization of the fluidic device 10.

[0012] As described above, the separation unit 30 has flat surfaces 31 and 32 on the ±Z sides. These flat surfaces 31 and 32 are parallel to the X direction and perpendicular to the Z direction. There is a fixed distance (flow path width W) between the flat surfaces 31 and 32 that face each other in the Z direction. Therefore, by transmitting ultrasonic waves with a wavelength λ from the ultrasonic element 60 and adjusting the flow path width W and the transmission frequency of the ultrasonic element 60 so that an integer multiple of half the wavelength λ / 2 matches the flow path width W, a standing wave SW can be formed between the flat surfaces 31 and 32 of the separation unit 30. The standing wave SW of this embodiment has multiple nodes and captures particles in the fluid at the node positions. The fluid flowing in from the inflow channel 20 connected to the -X and +Z sides of the separation unit 30 is captured at the node positions of the standing wave SW on the +Z side of the standing wave SW and flows along the fluid flow to the first outflow channel 40 provided on the +X and +Z sides. Furthermore, the fluid introduced from the inflow channel 20 into the separation unit 30 expands in the -Z direction due to the enlarged channel width. At this time, particles in the fluid are captured at the node positions of the standing wave SW on the +Z side, and therefore their movement toward the -Z side is suppressed. Therefore, a concentrated fluid flows out from the first outflow channel 40 provided on the +Z side of the separation unit 30, and a diluted fluid flows out from the second outflow channel 50 provided on the -Z side.

[0013] Incidentally, when turbulence occurs in such a separation unit 30, particles captured at the node position by the flow velocity component of the turbulence toward the -Z side move due to the pressure gradient of the ultrasound, and particles captured by the flow velocity component of the turbulence toward the +X side are returned to the inflow channel 20 side. Therefore, in this embodiment, in order to suppress the generation of turbulence in the separation unit 30 and maintain laminar flow along the X direction, the inflow channel 20 is formed in a tapered shape that increases in diameter toward the +X direction, as described above.

[0014] Furthermore, a recess 33 that is concave toward the -X side is provided on the -X side and the -Z side of the separation unit 30, i.e., at a position facing the second outflow channel 50. This recess 33 has a semicircular or semi-elliptical shape in cross section as viewed from the Y direction. For example, in the example shown in FIGS. 1 and 2, the recess 33 is formed in a semi-elliptical shape. Here, with respect to the elliptical shape of the recess 33, as shown in FIG. 2, the minor axis is parallel to the Z direction and the major axis extends concavely toward the -X side. The minor axis A of the minor axis satisfies W / 4≦A≦W / 2, where W is the channel width of the separation unit 30. The major axis B of the major axis satisfies A≦B≦2L, where L is the length of the separation unit 30 in the X direction (separation length). When A=B, the recess 33 is semicircular.

[0015] As described above, the first outlet flow channel 40 is connected to the +X side and the +Z side of the separation unit 30. The first outlet flow channel 40 is provided coaxially (main flow channel axis L1) with the inlet flow channel 20 and parallel to the X direction. Furthermore, the fluid flowing from the inlet flow channel 20 into the separation unit 30 flows into the separation unit 30 from the +X side opening end of the inlet flow channel 20 centered on the main flow channel axis L1 and is captured at the node position of the standing wave SW on the +Z side of the separation unit 30. The captured fine particles are then induced to flow into the first outlet flow channel 40 by the fluid flow along the main flow channel axis L1, causing a concentrated fluid containing a large amount of fine particles to flow out from the first outlet flow channel 40. For this reason, it is preferable that the flow channel diameter D3 of the -X side opening end of the first outlet flow channel 40 satisfy the relationship D3≧D2. Furthermore, the +X side opening end of the first outflow channel 40 is connected to a first outflow pipe (not shown) through which the concentrated fluid flows out. Therefore, the +X side opening end of the first outflow channel 40 is formed with a flow channel diameter corresponding to the pipe diameter of the first outflow pipe. When the flow channel diameters of the +X side opening end and the -X side opening end of the first outflow channel 40 are different, the flow channel is formed in a tapered shape from the -X side opening end to the +X side opening end. For example, in the example of FIG. 1, the pipe diameter of the first outflow pipe is smaller than that of the -X side opening end of the first outflow channel 40. In this case, the flow channel is formed in a tapered shape in which the flow channel diameter becomes smaller toward the +X side. This prevents the fluid flowing into the first outflow channel 40 from generating turbulence due to a sudden change in flow channel diameter, allowing fine particles in the concentrated fluid to flow into the first outflow pipe.

[0016] The second outlet flow channel 50 is connected to the +X side and the -Z side of the separation unit 30. The flow channel diameter D4 of the -X side open end of the second outlet flow channel 50 preferably satisfies the relationship D4≧D3. The second outlet flow channel 50 is also provided along the X direction and a sub-flow channel axis L2 that is parallel to the main flow channel axis L1. By satisfying the relationship D4≧D3, the diluted fluid separated in the separation unit 30 can be discharged from the second outlet flow channel 50. Furthermore, a second outlet pipe (not shown) that discharges the diluted fluid is connected to the +X-side opening end of the second outlet flow path 50. Therefore, the +X-side opening end of the second outlet flow path 50 is formed with a flow path diameter corresponding to the pipe diameter of the second outlet pipe. When the +X-side opening end and the −X-side opening end of the second outlet flow path 50 have different flow path diameters, the second outlet flow path 50 is tapered from the −X-side opening end toward the +X-side opening end. For example, in the example of FIG. 1 , the pipe diameter of the second outlet pipe is smaller than that of the −X-side opening end of the second outlet flow path 50. In this case, the second outlet pipe is tapered so that the flow path diameter decreases toward the +X side. This prevents turbulence due to a sudden change in flow path diameter from occurring in the fluid that flows into the second outlet flow path 50, thereby preventing the diluted fluid from flowing back into the separation unit 30.

[0017] [Fluid flow in the fluidic device 10] FIG. 3 is a schematic diagram showing the flow of fluid flowing through a separation section 70 of a conventional fluidic device. 3, an inlet flow channel 71 is connected to a separation unit 70 on the -X side, a first outlet flow channel 72 for flowing a concentrated fluid is connected to the +X side opposite the inlet flow channel 71, and a second outlet flow channel 73 is connected to the -Z side of the first outlet flow channel 72. The inlet flow channel 71 has the same diameter at its -X side opening end and its +X side opening end, i.e., the inlet flow channel 71 is formed in a tubular shape with a uniform flow channel diameter. The flow channel diameter of this inlet flow channel 71 is the flow channel diameter D1 of the introduction pipe connected to the fluidic device. The example shown in FIG. 3 is a simulation result when a fluid is introduced from the inflow channel 71 at a flow rate of 8 (l / h). As shown in FIG. 3, the fluid that flows into the separation unit 30 generates turbulence in the separation unit 30. 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 71 side also occurs. Turbulence is also generated when the fluid with the flow velocity component toward the inflow channel 71 collides with the fluid flowing in from the inflow channel 71. In this conventional separation unit 70, a vortex U1 is generated on the +Z side of the separation unit 70. This may cause particles in the fluid captured at the node of the standing wave SW to deviate from the pressure gradient of the ultrasound, resulting in a decrease in the amount of particles flowing into the first outflow channel 72.

[0018] Fig. 4 is a schematic diagram showing the flow of fluid flowing through the separation unit 30 of this embodiment. Fig. 4 shows the flow of fluid in the separation unit 30 when the flow rate of the fluid is 50 (l / h). In this embodiment, the vortex U2 is generated at a position on the -X side and the -Z side, but the vortex U2 is not generated on the main flow path axis L1 where a large amount of fine particles are contained. 3, the flow velocity of the fluid from the inlet flow channel 20 is high, and turbulence in the separation section 30 generates a vortex U1 on the +Z side more than in this embodiment. In contrast, in this embodiment, as described above, the inlet flow channel 20 is tapered, so the flow velocity of the fluid flowing into the separation section 30 is slower than in the conventional example. As a result, even if a vortex U2 is formed, it is only near the recess 33 that is off the main flow channel axis L1, and no flow velocity component returning to the inlet flow channel 20 appears.

[0019] In this embodiment, in order for the fluid that has flowed into the separation section 30 to maintain a laminar flow, the following two conditions are satisfied. The first condition is that the hydraulic diameter d of the +X side open end of the inflow channel 20, that is, the connecting portion with the separation section 30, satisfies the condition of the following formula (1).

[0020]

number

[0021] In equation (1), hydraulic diameter d is the quantity that represents the length equivalent to the diameter of a circular pipe, and is generally expressed as d = 4A / P, where A is the cross-sectional area of the pipe and P is the perimeter of the wetted edge of the cross section. Furthermore, ρ is the density of the fluid, V is the flow rate, and μ is the viscosity coefficient.

[0022] In this embodiment, the inflow channel 20 is tapered so that its diameter increases toward the separation unit 30, as described above. This reduces the flow rate of the fluid flowing into the separation unit 30, suppressing the generation of turbulence in the separation unit 30. However, if the diameter of the inflow channel 20 increases rapidly, turbulence occurs within the inflow channel 20, which in turn makes turbulence more likely to occur in the separation unit 30. The greater the flow rate of the fluid flowing from the inflow channel 20, the more likely it is to generate turbulence. In particular, this embodiment aims to provide a fluidic device 10 that can separate particles using standing waves SW even when a fluid is introduced at a flow rate of 200 (l / h). In this case, the tapered shape must be configured to prevent turbulence in the inflow channel 20 when a fluid with a flow rate of 200 (l / h) is introduced.

[0023] 5 and 6 are schematic diagrams showing the tapered shape of the inflow channel 20 of this embodiment. From the condition of the above formula (1), when a fluid at a flow rate of 200 (l / h) is introduced into the fluidic device 10, the hydraulic diameter d needs to be 38.4 mm or more. In addition, the flow channel diameter D1 of the opening end on the −X side of the inflow channel 20 through which the fluid is introduced is formed to be 3 mm or more. In this case, as shown in FIGS. 5 and 6, the second condition is that the inflow passage 20 is configured so that the sum of the taper angles α+β of the inflow passage 20 is 3.8 degrees or less. 5, in the case where the flow path diameter of inflow flow path 20 expands toward both the +Z side and the -Z side, taper angle α on the +Z side and taper angle β on the -Z side may each be 1.9 degrees. Alternatively, taper angle α on the +Z side and taper angle β on the -Z side may each be different angles; for example, taper angle α on the +Z side may be 1 degree, and taper angle β on the -Z side may be 2.8 degrees. Also, as shown in Figure 6, when the flow path diameter of the inlet flow path 20 is expanded only toward the +Z side, the taper angle β on the -Z side is 0 degrees, so the taper angle α on the +Z side needs to be 3.8 degrees or less. The examples in Figures 5 and 6 illustrate the cross section of the inlet flow channel 20 in the XZ plane including the main flow channel axis L1, but even when the inlet flow channel 20 is cross-sectioned at any cross section including the main flow channel axis L1, the inlet flow channel 20 is configured so that the sum of the taper angles α and β is 3.8 degrees or less.

[0024] The above conditions are for the fluidic device 10 of this embodiment when the target flow rate is 200 (l / h), and larger taper angles α and β may be used when introducing a fluid at a flow rate lower than that. In other words, by making the sum of the taper angles α+β 3.8 degrees or less, it is possible to suppress the generation of turbulence in the separation section 30 and prevent the fluid from returning to the inlet channel 20 when introducing a fluid at a flow rate lower than 200 (l / h).

[0025] In addition, in this embodiment, a recess 33 is provided in the separation unit 30. This ensures that the vortex U2 generated in the separation unit 30 occurs near the recess 33, and is more reliably prevented from occurring on the +Z side. In other words, the flow velocity component that forms the vortex U2 enters the recess 33 and travels along the semi-elliptical curved surface of the recess 33. The fluid that has traveled along the curved surface of the recess 33 is released to the +X side when it leaves the recess 33, thereby preventing the generation of a flow velocity component that travels toward the inlet flow channel 20.

[0026] [Effects of this embodiment] The fluidic device 10 of this embodiment includes an inflow channel 20 through which a fluid flows, a separation section 30 into which the fluid flows from the inflow channel 20 and into which a standing wave SW is formed along the Z direction by ultrasonic waves, a first outflow channel 40 through which the fluid flows out of the separation section 30, and a second outflow channel 50 through which the fluid flows out of the separation section 30. The inflow channel 20 is connected to the −X side of the separation section 30, the first outflow channel 40 is connected to the +X side of the separation section 30 opposite the inflow channel 20, and the second outflow channel 50 is connected to the +X side of the separation section 30 at a position different from the first outflow channel 40 in the Z direction. The inflow channel 20 has a larger channel diameter along the Z direction as it approaches the separation section 30.

[0027] In this fluidic device 10, even when a large flow rate of fluid, for example, 50 (l / h) to 200 (l / h), is introduced from the inlet channel 20, the generation of turbulent fluid flow in the separation section 30 is suppressed. In particular, the fluid becomes a laminar flow on the main channel axis L1 from the inlet channel 20 toward the first outlet channel 40. Even if a vortex U2 occurs in the separation section 30, it will be located away from the main channel axis L1, that is, in an area where it has little effect on capturing fine particles. As a result, the flow velocity component caused by the turbulence improves the efficiency of capturing fine particles at the nodes of the standing wave SW, allowing a concentrated fluid with a high concentration of fine particles to flow out of the first outlet channel 40.

[0028] In this embodiment, the separation section 30 includes a recess 33 that is recessed in a direction away from the second outflow channel 50 at a position facing the second outflow channel 50 on the −X side. As a result, even if a vortex U2 occurs in the separation section 30, the return of the fluid to the inlet flow channel 20 can be suppressed in the -X side and -Z side regions where the recessed portion 33 is provided away from the main flow channel axis L1.

[0029] The recess 33 has a semicircular or semielliptical cross section taken along a plane including the X and Z directions. As a result, the fluid flowing into the recess 33 advances along the arcuate surface (ellipsoidal surface) of the recess, and as it flows out of the recess 33, the flow velocity component heading toward the +X side increases and the flow velocity component heading toward the inflow channel 20 decreases. This makes it possible to suppress the generation of vortices near the main channel axis L1.

[0030] In this embodiment, the inflow channel 20 and the first outflow channel 40 extend along the X direction intersecting the Z direction. That is, the inflow channel 20 and the first outflow channel 40 are arranged on the main channel axis L1. As a result, the fine particles contained in the fluid introduced from the inlet flow path 20 to the separation section 30 can be captured at the node position on the main flow path axis L1 of the standing wave SW and then discharged from the first outlet flow path 40, allowing a concentrated fluid with a high concentration of fine particles to be discharged from the first outlet flow path 40.

[0031] In this embodiment, the first outflow channel 40 has a channel diameter that decreases with increasing distance from the separation section 30 . This allows the concentrated fluid to be guided from the first outlet flow channel 40 to the first outlet pipe, which has a smaller flow channel diameter. Furthermore, if the flow channel width of the first outlet flow channel 40 is suddenly reduced, a flow velocity component may be generated in the direction returning to the separation unit 30. However, by gradually narrowing the flow channel width, the flow velocity component returning to the separation unit 30 as described above can be reduced, and the generation of turbulence in the separation unit 30 can be suppressed.

[0032] The same is true for the second outflow channel 50, and the channel diameter decreases with increasing distance from the separation section 30. This makes it possible to suppress the generation of a flow velocity component in the direction returning to the separation section 30, and to suppress the generation of turbulence in the separation section 30, compared to when the flow path diameter of the second outflow path 50 is suddenly reduced.

[0033] In this embodiment, the separator 30 has flat surfaces 31 and 32 that are perpendicular to the Z direction. This allows a standing wave SW to be formed between the opposing flat surfaces 31 and 32.

[0034] [Variations] The present invention is not limited to the above-described embodiments, and the present invention includes configurations obtained by modifications, improvements, and appropriate combinations of the embodiments within the scope that can achieve the object of the present invention.

[0035] (Variation 1) In the above embodiment, the configuration in which the recess 33 is provided in the separation section 30 has been exemplified, but the recess 33 is not essential, and for example, the configuration in which the recess 33 is not provided may also be adopted. FIG. 7 is a diagram showing the flow path of the fluid flowing through the separation section 30 when no recess is provided. The inlet flow path 20 is formed so that the flow path diameter increases as it approaches the separation section 30, as in the above embodiment, and is configured to satisfy the first condition, equation (1), and to satisfy the second condition, that the sum of the taper angles α and β of both is 3.8 degrees or less. 7, even in this case, a vortex U2 is formed at a position away from the main flow path axis L1 on the -X side and the -Z side of the separation unit 30, even without the recess 33. This makes it possible to suppress the generation of turbulence in other parts of the separation unit 30, and similarly to the above embodiment, it is possible to suppress the movement of the particles captured by the standing wave SW toward the inflow flow path 20 side and the second outflow flow path 50 side.

[0036] (Variation 2) In the above embodiment, an example has been shown in which the flow channel diameter of the inflow channel 20 increases toward the separation section 30, but the cross-sectional shape of the flow channel may also be modified. For example, the flow channel cross section may be deformed so that it has a circular flow channel cross section on the −X side of inflow channel 20 and becomes rectangular as it approaches separation section 30. Alternatively, the flow channel diameter may be enlarged on the −X side of inflow channel 20, and the flow channel cross section may be deformed from a circular cross section to a rectangular cross section on the +X side of inflow channel 20.

[0037] Similarly, the first outflow channel 40 and the second outflow channel 50 may have a rectangular cross section on the separation section 30 side and may have a cross section that becomes circular toward the +X side.

[0038] (Variation 3) In the above embodiment, the inflow channel 20 and the first outflow channel 40 are connected to the +Z side of the separation unit 30, but the present invention is not limited to this. For example, when a first-order standing wave SW is formed by the ultrasonic element 60, the node position is the central position in the Z direction of the separation unit 30. In this case, the inflow channel 20 is connected to the -X side of the separation unit 30 at the central position in the Z direction, and the first outflow channel 40 is connected to the +X side of the separation unit 30 at the central position in the Z direction. Furthermore, it is preferable that the second outflow channels 50 are provided on the +X side of the separation unit 30, on the +Z side and the -Z side of the first outflow channel 40. Similarly, it is preferable that the recesses 33 are provided on the +X side of the separation unit 30, on the +Z side and the -Z side of the inflow channel 20, that is, at positions facing each of the two second outflow channels 50.

[0039] Summary of this disclosure A fluidic device according to a first aspect of the present disclosure is a fluidic device that separates microparticles in a fluid using ultrasound, 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 along a first direction by the ultrasound, 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 the first direction, and the inlet flow path has a flow path diameter that increases as it approaches the separation section.

[0040] This reduces the flow velocity of the fluid in the inlet flow channel while maintaining laminar flow, and suppresses the generation of turbulence when the fluid flows into the separation section. Therefore, the particles captured at the node position of the standing wave can be flowed into the first outlet flow channel where they were captured, without being swept away by the turbulent fluid flow toward the inlet flow channel or the second outlet flow channel, and the decrease in the ultrasonic wave capture efficiency can be suppressed.

[0041] In the fluidic device of this aspect, the separation section has a recess that is recessed in a direction away from the second outflow channel at a position facing the second outflow channel on the one end side. This allows a vortex to be formed at a position away from the inlet flow path of the separation section, thereby preventing the inconvenience of fluid flowing into the separation section from the inlet flow path forming a vortex near the extension of the inlet flow path and generating turbulence.

[0042] In the fluidic device of this aspect, the recess has a semicircular or semielliptical cross-sectional shape when cut along a plane including the first direction and a second direction from the inflow channel toward the first outflow channel. This allows the fluid to flow along the arcuate or semi-elliptical surface of the recess, thereby suppressing the flow of the fluid toward the inflow channel, thereby suppressing the problem of turbulence caused by the fluid heading toward the inflow channel and the fluid flowing from the inflow channel into the separation section colliding with each other.

[0043] In the fluidic device of this aspect, the inflow channel and the first outflow channel extend along a second direction intersecting the first direction. This allows particles in the fluid that flows in along the axis of the inlet flow path and the first outlet flow path to be captured at the node position of the standing wave SW, and then flowed by the fluid along the axis, allowing the particles to flow out of the first outlet flow path.

[0044] In the fluidic device of this aspect, the first outflow channel has a channel diameter that decreases with increasing distance from the separation section. This makes it possible to suppress the occurrence of turbulent flow in the fluid, and to suppress the movement of fine particles toward the inflow flow path side due to the turbulent flow, compared to when the flow path diameter of the first outflow flow path is suddenly reduced.

[0045] In the fluidic device of this aspect, the second outflow channel has a channel diameter that decreases with increasing distance from the separation section. This makes it possible to suppress the occurrence of turbulent flow in the fluid, and to suppress the movement of fine particles toward the inflow flow path side due to the turbulent flow, compared to when the flow path diameter of the first outflow flow path is suddenly reduced.

[0046] In the fluidic device of this aspect, the separation section has a flat surface that is perpendicular to the first direction. This allows ultrasonic waves reflected by the flat surface to form standing waves. [Explanation of symbols]

[0047] 10...fluidic device, 20...inlet flow path, 30...separation section, 31...flat surface, 32...flat surface, 33...recess, 40...first outlet flow path, 50...second outlet flow path, 60...ultrasonic element, L1...main flow path axis, L2...sub-flow path axis, SW...standing wave.

Claims

1. A fluidic device that separates particles in a fluid using ultrasound, 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 along a first direction by the ultrasonic waves; 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 the first direction, The inflow channel has a channel diameter that increases as it approaches the separation section. Fluidic devices.

2. the separation portion includes a recessed portion that is recessed in a direction away from the second outflow channel at a position facing the second outflow channel on the one end side, The fluidic device according to claim 1 .

3. the recess has a semicircular or semielliptical cross-sectional shape when cross-sectioned along a plane including the first direction and a second direction from the inflow channel toward the first outflow channel; The fluidic device according to claim 2 .

4. The inflow channel and the first outflow channel extend along a second direction intersecting the first direction. The fluidic device according to claim 1 .

5. The first outflow channel has a channel diameter that decreases with increasing distance from the separation section. The fluidic device according to claim 1 .

6. The second outflow channel has a channel diameter that decreases with increasing distance from the separation section. The fluidic device according to claim 1 .

7. The separation portion has a flat surface perpendicular to the first direction. The fluidic device according to claim 1 .

Images