Fluidic device
By designing a flow channel structure with a concave reflective surface and an ultrasonic application surface in the fluid device, the problem of unstable particle capture in the fluid device was solved, achieving stable capture at the desired location and environmental protection effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SEIKO EPSON CORP
- Filing Date
- 2022-10-10
- Publication Date
- 2026-06-19
AI Technical Summary
In the prior art, fluid devices that capture particles generated by standing waves are difficult to stably capture particles at the desired location, and the conditions for the generation of standing waves are easily disturbed.
Design a fluid device in which the reflective surface in the flow channel has a concave curved shape, the ultrasonic application surface faces the reflective surface and forms a focal point on the surface where the flow directions of the fluid intersect, the ultrasonic application surface and the reflective surface have a parabolic or concentric arc shape when viewed in cross section, multiple ultrasonic elements are in phase, and the ultrasonic frequency is in the range of 300kHz to 50MHz.
Without requiring strict standing wave generation conditions, it can stably capture particles at desired locations, broadening the application range of fluid devices. It is suitable for particle separation in domestic drainage, industrial products, and pharmaceuticals, reducing environmental pollution.
Smart Images
Figure CN115957564B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a fluid device. Background Technology
[0002] A fluid device that acoustically aggregates particles in a fluid has long been known.
[0003] For example, the fluid device disclosed in Non-Patent Document 1 includes: a flow channel substrate (glass substrate) with flow channels formed thereon, and a piezoelectric element disposed on the flow channel substrate. Ultrasonic waves generated by the piezoelectric element are transmitted into the flow channels via the flow channel substrate, thereby generating standing waves in the fluid within the flow channels. Particles in the fluid are captured within a predetermined range within the flow channels by passing through the pressure gradient of the fluid formed by the standing waves.
[0004] Although the fluid device described in Non-Patent Document 1 is a device that converges particles in a fluid by means of a standing wave generated by ultrasound, it is difficult to construct a fluid device that can stably capture particles at the desired location because the conditions for the generation of the standing wave can change due to interference.
[0005] Non-Patent Literature 1: Nobutoshi Ota, 6 others, "Enhancement in acoustic focusing of micro and nanoparticles by thinning a microfluidic device", December 2019, Royal Society Open Science, Vol. 6, No. 2, Reporter No. 181776 Summary of the Invention
[0006] The fluid device according to a first aspect of the present invention comprises: a flow channel for the flow of fluid; an ultrasonic element for transmitting ultrasonic waves, serving as a flow channel wall, the flow channel having an ultrasonic application surface for applying the ultrasonic waves transmitted from the ultrasonic element to the fluid, and a reflective surface for reflecting the ultrasonic waves applied to the fluid from the ultrasonic application surface, the reflective surface having a concave curved shape.
[0007] In the fluid device of the first embodiment, it is preferable that the reflective surface, when viewed in cross-section at the surface intersecting with the flow direction of the fluid, has a parabolic shape that forms a focal point within the flow channel.
[0008] In the fluid device of the first embodiment, preferably, the ultrasonic wave application surface faces the reflective surface.
[0009] In the fluid apparatus of the first embodiment, preferably, the ultrasonic wave applying surface faces the reflecting surface, and when viewed in cross-section at the surface where the ultrasonic wave applying surface and the reflecting surface intersect relative to the flow direction of the fluid, they have a concentric arc shape centered on an imaginary point within the flow channel.
[0010] In the fluid apparatus of the first embodiment, it is preferable to include a plurality of ultrasonic elements, the flow channel having a plurality of ultrasonic application surfaces for applying ultrasonic waves from the plurality of ultrasonic elements to the fluid, and a plurality of reflective surfaces respectively facing the plurality of ultrasonic application surfaces, wherein the plurality of ultrasonic application surfaces and the plurality of reflective surfaces, when viewed in cross-section, have concentric arc shapes centered on the same imaginary point.
[0011] In the fluid device of the first type, preferably, the phases of the ultrasonic waves transmitted from the plurality of ultrasonic elements are consistent with each other.
[0012] In the fluid device of the first embodiment, preferably, the flow channel has a circular cross-section, and when the diameter of the flow channel cross-section is set to D, the frequency of the ultrasonic wave is set to f, and the velocity of the ultrasonic wave is set to c, the width w of the ultrasonic wave application surface satisfies the following mathematical formula 1.
[0013] Mathematical formula 1:
[0014] Attached Figure Description
[0015] Figure 1 A cross-sectional view schematically showing a portion of the fluid apparatus of the first embodiment.
[0016] Figure 2 for Figure 1 A sectional view along the AA line.
[0017] Figure 3 A perspective view illustrating the convergence region of the flow channel in the fluid apparatus of the first embodiment.
[0018] Figure 4 A perspective view schematically showing a portion of the fluid device according to the second embodiment.
[0019] Figure 5 A cross-sectional view schematically illustrating the fluid apparatus of the second embodiment.
[0020] Figure 6 This is a schematic diagram illustrating the beam width of the ultrasonic wave in the fluid apparatus of the second embodiment.
[0021] Figure 7This is a schematic diagram illustrating a variation of the fluid apparatus according to the first embodiment. Detailed Implementation
[0022] First Implementation Method
[0023] The fluid device of the first embodiment will be described below.
[0024] Figure 1 A cross-sectional view schematically showing a portion of the fluid device 10 of this embodiment. Figure 2 for Figure 1 The AA-line sectional view shows the fluid device 10, which includes a flow channel substrate 30 forming a flow channel 20 and an ultrasonic application device 40 disposed on the flow channel substrate 30. In the following description, the flow direction of the fluid S flowing in the flow channel 20 is defined as the X direction, the direction orthogonal to the X direction is defined as the Y direction, and the direction orthogonal to both the X and Y directions is defined as the Z direction.
[0025] In the fluid device 10 of this embodiment, ultrasonic waves emitted from the ultrasonic wave application device 40 are applied to the fluid S flowing in the convergence region R, which is a part of the X-direction region of the flow channel 20, thereby causing the particles or even tiny fibers (hereinafter referred to as particles M) dispersed in the fluid S to converge. Although the fluid S is not specifically limited, it is, for example, water.
[0026] In such a fluid device 10, for example, by providing a fluid inlet for the flow channel 20 to allow the fluid S to flow in and a fluid outlet for the flow channel 20 to allow the fluid S to flow out, it is possible to concentrate the particles M within the flow channel 20.
[0027] Alternatively, by providing a concentration channel for selectively allowing the flow of fluid S containing converged particles M to flow through the flow channel 20, and a discharge channel for selectively allowing the flow of other fluids S to flow through, it is possible to concentrate the particles M in the fluid S.
[0028] In addition, Figure 1 The diagram schematically illustrates the state of particles M convergent within flow channel 20. Furthermore, in... Figure 2 In the diagram, the particle M is omitted, and the direction of travel of the ultrasonic wave incident into the flow channel 20 is indicated by an arrow.
[0029] Flow channel substrate 30
[0030] like Figure 1 as well as Figure 2 As shown, the flow channel substrate 30 includes a base substrate 31 and a packaging substrate 32 (see reference). Figure 2The substrate 31 has a recess 311 that is concave along the X direction and towards the +Z side, and the encapsulation substrate 32 is configured to cover the recess 311 of the substrate 31. The wall portion 33 is disposed along one side of the recess 311 and has a reflective surface 331 that serves as the flow channel wall. The flow channel 20 is formed mainly through the lower surface of the encapsulation substrate 32, the other side and bottom surface of the recess 311 of the substrate 31, and the reflective surface 331 of the wall portion 33.
[0031] Furthermore, in the convergence region R, which is part of the X-direction region of the flow channel 20, the groove 311 of the base plate 31 includes a portion that is formed with a larger width in the Y-direction compared to other portions, and an ultrasonic application device 40 is arranged in this portion in a manner opposite to the reflective surface 331 of the wall portion 33.
[0032] Here, Figure 3 A three-dimensional view is provided to briefly illustrate the convergence region R of the flow channel 20. Additionally, in Figure 3 In the diagram, the wall portion 33 and the ultrasonic application device 40 are represented by solid lines, while the portions of the base plate 31 and the encapsulation plate 32 facing the flow channel 20 are represented by dashed lines.
[0033] like Figure 3 As shown, the convergence region R of the flow channel 20 is formed by the lower surface of the encapsulation substrate 32, the bottom surface of the groove 311 of the bottom substrate 31, the reflective surface 331 of the wall portion 33, and the ultrasonic application surface 41 of the ultrasonic application device 40.
[0034] Reflective surface 331
[0035] like Figure 2 As shown, when viewed in cross-section (i.e., YZ cross-section) at a surface orthogonal to the flow direction (X direction) of the fluid, the reflective surface 331 has a parabolic shape with the axis parallel to the Y direction set as the axis of symmetry SL, and this parabolic shape forms a focal point F within the flow channel 20.
[0036] For example, if the YZ section of the reflecting surface 331 has a parabolic shape as represented by the following equation (1), the distance from the origin O of the parabolic shape to the focal point F will be 1 / 4a. Here, the flow channel 20 is formed such that the shortest distance from the portion of the reflecting surface 331 corresponding to the origin O of the parabolic shape (set as the bottom 332) to the ultrasonic wave application surface 41 is greater than the distance from the bottom 332 to the focal point F (that is, 1 / 4a).
[0037] Mathematical formula 2
[0038] y = ax 2 …Formula (1)
[0039] In addition, such as Figure 3 As shown, the reflective surface 331 forms a linear focal point FL in the X direction, which is a continuous parabolic focal point F within the flow channel 20.
[0040] In such a structure, when an ultrasonic wave along the axis of symmetry SL (i.e., the Y direction) is incident on the reflecting surface 331, the incident angle and reflection angle of the ultrasonic wave become symmetrical with respect to the normal of the reflecting surface 331, and the ultrasonic wave reflected on the reflecting surface 331 is focused on the linear focal point FL.
[0041] Ultrasonic application device 40
[0042] The ultrasonic application device 40 is configured to include one or more ultrasonic elements and to transmit ultrasonic waves as plane waves to the reflecting surface 331. The ultrasonic elements may have, for example, piezoelectric actuators or vibrating plates as oscillators.
[0043] For example, in the case where an ultrasonic element has a piezoelectric actuator as an oscillator, sound waves are generated by applying a driving voltage to the piezoelectric actuator, causing the piezoelectric actuator to vibrate itself.
[0044] Furthermore, when the ultrasonic element has a vibrating plate as an oscillator, sound waves are generated by applying a driving voltage to a piezoelectric film formed on the vibrating plate, causing the vibrating plate to vibrate.
[0045] Alternatively, the ultrasonic element may be configured such that it comprises a vibrating plate serving as an oscillator and a substrate disposed opposite to the vibrating plate, and electrodes formed on the vibrating plate and the substrate respectively constitute an electrostatic actuator. In this case, the ultrasonic element generates sound waves by applying a driving voltage to the electrostatic actuator, thereby causing the vibrating plate to vibrate.
[0046] Alternatively, the ultrasonic application device 40 may be configured to include not only the ultrasonic element described above, but also an acoustic matching layer, an acoustic lens, etc.
[0047] In the ultrasonic application device 40, the frequency of the ultrasonic waves generated by the ultrasonic element is not particularly limited, but ultrasonic waves in the frequency band of 300 kHz to 50 MHz are preferred. For example, in the low-frequency region of ultrasonic waves, specifically in the frequency band of 10 kHz to 300 kHz, cavitation occurs in the fluid S, making it unsuitable for capturing particles M in the fluid S. Therefore, ultrasonic waves with a frequency of 300 kHz or higher are preferred. Furthermore, when using ultrasonic waves in the frequency band of 50 MHz or lower, a general drive source can be used as the drive source for the ultrasonic element.
[0048] In this embodiment, the ultrasonic application device 40 has an ultrasonic application surface 41 for applying ultrasonic waves emitted from the ultrasonic element to the fluid S. Here, the ultrasonic application surface 41 may also be formed by a vibrating plate constituting the ultrasonic element. Furthermore, if the ultrasonic application device 40 includes an acoustic matching layer or an acoustic lens, the ultrasonic application surface 41 may also be formed by an acoustic matching layer or an acoustic lens. As described above, this ultrasonic application surface 41 becomes part of the flow channel wall constituting the convergence region R of the flow channel 20.
[0049] Furthermore, in this embodiment, it is preferable that the ultrasonic wave applying device 40 transmits highly directional ultrasonic waves toward the reflecting surface 331. Specifically, it is desirable that the near-field length N of the ultrasonic waves transmitted from the ultrasonic wave applying device 40 is greater than the shortest distance from the ultrasonic wave applying surface 41 to the bottom 332 of the reflecting surface 331.
[0050] Here, the near-field length N of the ultrasonic wave transmitted from the ultrasonic wave application device 40 of this embodiment is expressed by the following formula (2) or formula (3). Specifically, when the shape of the vibration region (hereinafter referred to as the vibration part) of the vibrating plate constituting the ultrasonic wave application device 40 is circular, the following formula (2) holds; when the shape of the vibration part is rectangular, the following formula (3) holds.
[0051] Mathematical Formula 3
[0052]
[0053]
[0054] In equations (2) and (3) above, the frequency (Hz) of the ultrasonic wave is set as f, and the velocity of sound (m / s) is set as c. Furthermore, in equation (2), the diameter (m) of the circular vibrating part is set as d, and in equation (3), the length (m) of the rectangular vibrating part is set as L. Furthermore, the coefficient k specified in equation (3) is defined as shown in Table 1 below. The dimension ratios in Table 1 below are the ratios of the shorter side to the longer side of the vibrating part; when the dimension ratio is 1, the shape of the vibrating part is square. Additionally, since the maximum value of the dimension ratio is 1, the maximum value of the specified coefficient k is 1.37.
[0055] Table 1
[0056] Size ratio k 1 1.37 0.9 1.25 0.8 1.15 0.7 1.09 0.6 1.04 0.5 1.01 0.4 1 0.3 0.99
[0057] Capture of particle M
[0058] According to the above structure, the ultrasonic waves applied to the fluid S from the ultrasonic application surface 41 are incident relative to the reflecting surface 331 in the direction along the axis of symmetry SL (i.e., the Y direction). The ultrasonic waves reflected by the reflecting surface 331 are concentrated at the linear focal point FL, and constructive interference is generated. As a result, the sound pressure is concentrated at the linear focal point FL, and a sound pressure gradient is generated such that the particles M remain at the linear focal point FL, thereby capturing the particles M in the fluid S near the linear focal point FL.
[0059] Effects of the first implementation method
[0060] As described above, the fluid device 10 of this embodiment includes: a flow channel 20 through which a fluid S flows; and an ultrasonic wave application device 40 that transmits ultrasonic waves. As a wall of the flow channel, the flow channel 20 has an ultrasonic wave application surface 41 for applying ultrasonic waves to the fluid S, and a reflective surface 331 for reflecting ultrasonic waves applied to the fluid S from the ultrasonic wave application surface 41. The reflective surface 331 has a concave curved surface shape. In particular, in this embodiment, the YZ cross-section of the reflective surface 331 has a parabolic shape that forms a focal point F within the flow channel 20.
[0061] According to this structure, the reflecting surface 331 forms a linear focal point FL continuously connected to the focal point F within the flow channel 20, and the ultrasonic waves reflected by the reflecting surface 331 are concentrated at the linear focal point FL within the flow channel 20. This creates a region with strong sound pressure near the linear focal point FL within the flow channel 20, thereby enabling the capture of particles M within this region.
[0062] Therefore, in the fluid device 10 of this embodiment, it is not necessary to generate standing waves under strict conditions, and it is possible to easily capture particles M at the desired location.
[0063] Furthermore, in the fluid device 10 of this embodiment, the ultrasonic wave application surface 41 is positioned opposite the reflecting surface 331. With this structure, since the ultrasonic waves emitted from the ultrasonic wave application surface 41 are easily incident along the parabolic axis of symmetry SL relative to the reflecting surface 331, the ultrasonic waves can be appropriately concentrated at the linear focal point FL within the flow channel 20. As a result, the particles M can be captured more effectively.
[0064] The fluid device 10 described above can appropriately separate the particles M contained in the fluid S, thereby broadening the scope of application of the fluid device 10. For example, by allowing domestic wastewater discharged from a washing machine or kitchen to flow into the fluid device 10, the particles M contained in the domestic wastewater can be separated. In this case, fine composite fiber contained in the washing water, abrasive powder of detergent contained in the kitchen wastewater, etc., can also be separated, thereby suppressing environmental damage caused by harmful substances such as composite waste.
[0065] Furthermore, the fluid device 10 can also be preferably used for the separation of particles M dispersed in media such as industrial products and pharmaceuticals, as well as the separation of cells and viruses in liquids.
[0066] Second Implementation Method
[0067] Next, refer to Figures 4-6 The fluid device of the second embodiment will be described. Furthermore, the same reference numerals are used for structures identical to those in the first embodiment, and there are instances where descriptions are omitted or simplified.
[0068] Figure 4 A perspective view schematically showing a portion of the fluid device 10A according to the second embodiment. Figure 5 This is a cross-sectional view of the fluid device 10A of the second embodiment, cut along a plane orthogonal to the flow direction of the fluid S.
[0069] like Figure 4 as well as Figure 5 As shown, the fluid device 10A includes a cylindrical member 50, a plurality of ultrasonic application devices 40 disposed on the cylindrical member 50, and a flow channel 20A for the flow of fluid S in the X direction. In this fluid device 10A, similar to the first embodiment, ultrasonic waves emitted from the ultrasonic application devices 40 are applied to the fluid S flowing in the convergence region R, which is a part of the X direction region of the flow channel 20, thereby causing the particles M dispersed in the fluid S to converge.
[0070] The cylindrical component 50 has a cylindrical shape along the central axis C in the X direction, and the flow channel 20A in the fluid device 10A is formed mainly through the inner peripheral surface 51 of the cylindrical component 50. When viewed in cross-section (i.e., YZ cross-section) on a plane orthogonal to the flow direction of the fluid S, the inner peripheral surface 51 of the cylindrical component 50 has a circular shape centered on the central axis C.
[0071] The ultrasonic application device 40 has the same structure as in the first embodiment. In this embodiment, the ultrasonic application device 40 is disposed within a through hole formed on the cylindrical member 50 and has an ultrasonic application surface 41 that serves as the flow channel wall. That is, in this embodiment, the convergence region R of the flow channel 20 is formed through the inner peripheral surface 51 of the cylindrical member 50 and the ultrasonic application surface 41 of the ultrasonic application device 40.
[0072] Furthermore, multiple ultrasonic application devices 40 are configured to be located at different positions on the same circumference centered on the central axis C of the cylindrical component 50, and to transmit ultrasonic waves that are phase-matched to each other.
[0073] In this embodiment, each ultrasonic application surface 41 of the plurality of ultrasonic application devices 40 is preferably an arc shape that is concentric with the inner circumferential surface 51 of the cylindrical member 50 when viewed in cross-section (i.e., YZ cross-section) at a surface orthogonal to the flow direction of the fluid S. Such ultrasonic application surfaces 41 apply ultrasonic waves toward the central axis C of the cylindrical member 50 in the diametrical direction of the cylindrical member 50. Furthermore, such ultrasonic application surfaces 41 are preferably formed, for example, by means of an acoustic matching layer or an acoustic lens constituting the ultrasonic application device 40.
[0074] Furthermore, in this embodiment, the ultrasonic application device 40 is preferably one that transmits ultrasonic waves with high directivity. Specifically, the near-field length N of the ultrasonic waves transmitted from the ultrasonic application device 40 is preferably greater than the flow channel diameter D, which is the diameter of the inner circumferential surface 51 of the cylindrical component 50 (i.e., the diameter of the flow channel cross-section). In addition, the formula for calculating the near-field length N can be obtained using equation (2) or equation (3) described in the first embodiment above.
[0075] According to the above structure, the ultrasonic wave applied to the fluid S from the ultrasonic wave application surface 41 passes through the central axis C of the cylindrical component 50 and reaches the region of the inner circumferential surface 51 of the cylindrical component 50 opposite to the ultrasonic wave application surface 41 (i.e., the reflecting surface 511). The ultrasonic wave is incident on the reflecting surface 511 at an angle of 0° and reflected by the reflecting surface 511, thus changing its orientation by 180° from the incident direction and passing through the central axis C again within the flow channel 20A. Therefore, the ultrasonic wave applied to the fluid S from the ultrasonic wave application surface 41 and the ultrasonic wave reflected by the reflecting surface 511 are each concentrated on the central axis C, and constructive interference is generated between them.
[0076] Here, in this embodiment, the cylindrical component 50 is provided with a plurality of (e.g., three) ultrasonic application devices 40, and the inner peripheral surface 51 of the cylindrical component 50 includes a plurality of (e.g., three) reflective surfaces 511 opposite to each ultrasonic application surface 41. Each YZ section of these inner peripheral surfaces 51 and reflective surfaces 511 has a circular arc shape.
[0077] Therefore, in this embodiment, as Figure 5 As shown, not only ultrasound waves from one ultrasound application surface 41, but also ultrasound waves from multiple ultrasound application surfaces 41 overlap near the central axis C. Furthermore, ultrasound waves from multiple reflecting surfaces 511 also overlap near the central axis C. In addition, since the ultrasound waves from multiple ultrasound application surfaces 41 are in phase with each other, the ultrasound waves from multiple ultrasound application surfaces 41 and from multiple reflecting surfaces 511, through overlapping near the central axis C, produce constructive interference.
[0078] Therefore, in this embodiment, the sound pressure is concentrated near the central axis C in the flow channel 20A, and a sound pressure gradient is generated such that the particles M will remain near the central axis C, thereby capturing the particles M in the fluid S.
[0079] Furthermore, in this embodiment, there is a preferred range of beam widths as the beam width of the ultrasonic wave applied from the ultrasonic application surface 41.
[0080] Specifically, if the diameter d of the circular vibrating part or the long side dimension L of the rectangular vibrating part in the ultrasonic application device 40 is equal to the beam width w of the ultrasonic wave, and if K is set to kf / 4c in the above equation (2) (or K is set to f / 4c in the above equation (3), then the following equation (4) holds.
[0081] Mathematical expression 4
[0082] N = Kw 2 …Formula (4)
[0083] Furthermore, under the condition that the channel diameter D is less than the near-field length N, the lower limit of the beam width w can be specified by the following equations (5) to (7).
[0084] Mathematical formula 5
[0085] D < N = Kw 2 …Formula (5)
[0086]
[0087]
[0088] Furthermore, an upper limit for the beam width w can be specified under the condition that when an ultrasonic wave from any ultrasonic application surface 41 arrives at the reflecting surface 511 as an incident wave, the reflected wave emitted from the reflecting surface 511 will not directly reach the ultrasonic application surface 41 adjacent to the arbitrary ultrasonic application surface 41.
[0089] For example, Figure 6 A diagram illustrating the diffusion of ultrasound waves from an ultrasound application surface 41 positioned at the very center of the diagram.
[0090] exist Figure 6 In the equation (8), the angle θ of the arc formed by the reflecting surface 511 reached by the incident wave is geometrically represented by the following equation (8).
[0091] Mathematical formula 6
[0092]
[0093] In addition, Figure 6 In the equation (9), the angle φo of the arc formed by the region of the inner circumferential surface 51 reached by the reflected wave is geometrically represented by the following equation (9).
[0094] Mathematical Formula 7
[0095] φ0=φ+θ=3θ…Equation (9)
[0096] Furthermore, φ in equation (9) above is, in Figure 6 The angle is formed by connecting points A and B at both ends of the reflecting surface and point P where the reflected wave converges. Let point P be an angle such that although the reflected wave converges, constructive interference does not occur due to the phase deviation between them.
[0097] Here, in order to prevent the reflected wave from directly reaching the adjacent ultrasonic application surface 41, the following equation (10) needs to be satisfied. Furthermore, in the following equation (10), φ i The angle formed by the central axes of adjacent ultrasonic application surfaces 41 is such that the central axis of the ultrasonic application surface 41 intersects the central axis C of the cylindrical portion. Furthermore, the maximum value of φi is the angle when the two ultrasonic application devices 40 are arranged opposite each other with the central axis C of the cylindrical portion apart, which is 180°.
[0098] Mathematical formula 8
[0099] φ0<φ i …Formula (10)
[0100] Based on the above equations (8) to (10), the following equations (11) to (13) are valid.
[0101] Mathematical formula 9
[0102]
[0103]
[0104]
[0105] Therefore, according to equation (7) and equation (13) above, the beam width w is expressed by the following equation (14).
[0106] Mathematical formula 10
[0107]
[0108] Here, an example that satisfies equation (14) above is illustrated.
[0109] Regarding the lower limit of the beam width w
[0110] Mathematical formula 11
[0111]
[0112] When K = kf / 4c and k ≤ 1.37, the following equation (15) holds.
[0113] Mathematical expression 12
[0114]
[0115] Furthermore, regarding the upper limit of the beam width w...
[0116] Mathematical formula 13
[0117]
[0118] Let it be φ i When the maximum value is 180°, the following equations (16) and (17) hold true.
[0119] Mathematical formula 14
[0120]
[0121]
[0122] When equations (15) and (17) are substituted into equation (14), equation (18) holds true.
[0123] Mathematical formula 15
[0124]
[0125] Therefore, in this embodiment, the beam width w preferably satisfies the above formula (18). In addition, the beam width w is set to be equal to the width of the ultrasonic application surface 41, specifically the diameter D of the circular vibrating part in the ultrasonic application device 4, or the long side dimension L of the rectangular vibrating part.
[0126] Effects of the second implementation method
[0127] The fluid device 10A of this embodiment, like that of the first embodiment, has a concave curved reflective surface 511. Furthermore, the ultrasonic application surface 41 is opposite to the reflective surface 511, and when viewed in YZ cross section, the ultrasonic application surface 41 and the reflective surface 511 have concentric arc shapes with the central axis C (corresponding to an imaginary point in the flow channel 20) as the center.
[0128] According to this structure, by focusing the ultrasonic waves applied from the ultrasonic application surface 41 and the ultrasonic waves reflected by the reflective surface 511 near the central axis C in the flow channel 20, it is possible to create a region in the flow channel 20 where a strong sound pressure is generated and to capture the particles M in that region.
[0129] Therefore, in the fluid device 10A of this embodiment, similar to the first embodiment, it is not necessary to generate standing waves under strict conditions, and it is easier to capture particles M at the desired location.
[0130] In the fluid device 10A of this embodiment, the flow channel 20 has a plurality of ultrasonic application surfaces 41 and a plurality of reflecting surfaces 511 respectively opposite to the plurality of ultrasonic application surfaces 41, and the plurality of ultrasonic application surfaces 41 and the plurality of reflecting surfaces 511 have concentric arc shapes centered on the central axis C (corresponding to the same imaginary point) within the flow channel 20. According to this structure, by concentrating the ultrasonic waves applied from the plurality of ultrasonic application surfaces 41 and the ultrasonic waves reflected by the plurality of reflecting surfaces 511 near the central axis C within the flow channel 20, it is possible to generate a region within the flow channel 20 where stronger sound pressure is applied, thereby enabling the appropriate capture of particles M.
[0131] In the fluid device 10A of this embodiment, the phases of the ultrasonic waves applied to the fluid S from the plurality of ultrasonic application surfaces 41 are consistent with each other. According to this structure, the ultrasonic waves concentrated near the central axis C in the flow channel 20 can appropriately generate constructive interference.
[0132] In the fluid device 10A of this embodiment, the width of the ultrasonic application surface 41 (i.e., the beam width w) is preferably such that it satisfies the above-described formula (14), and in particular, the above-described formula (18). With such a structure, adjacent ultrasonic application surfaces 41 do not cause negative effects on each other, and can emit highly directional ultrasonic waves toward their corresponding reflecting surfaces 511. As a result, particles M can be appropriately captured.
[0133] Variations
[0134] This invention is not limited to the embodiments described above. Modifications, improvements, and structures obtained by appropriately combining the embodiments are also included in this invention.
[0135] Although in the first and second embodiments, the ultrasonic application device 40 has an ultrasonic application surface 41 that serves as a flow channel wall, it is also possible to configure a wall member between the ultrasonic application device 40 and the fluid S, and this wall member has an ultrasonic application surface that serves as a flow channel wall. That is, the ultrasonic waves emitted from the ultrasonic application device 40 can also be applied to the fluid S via the wall member.
[0136] In the fluid device 10 of the first embodiment, an ultrasonic application device 40 is provided, which has a planar ultrasonic application surface 41. As a variation thereof, such as... Figure 7 As shown in the schematic diagram, a wall component 60 constituting the flow channel wall can also be used, and a plurality of ultrasonic application devices 40 are provided relative to the wall component 60. In this case, the wall component 60 has an ultrasonic application surface 61 that applies each ultrasonic wave transmitted from the plurality of ultrasonic application devices 40 to the fluid S. Furthermore, it is preferable that the plurality of ultrasonic application devices 40 form a plane wave W from the ultrasonic application surface 61 toward the reflecting surface 331 by shifting the phase of the transmitted wave relative to each other according to their respective positions.
[0137] Although in the second embodiment, the ultrasonic application surface 41 and the reflecting surface 511 have the same circular arc shape, the present invention is not limited thereto. For example, the ultrasonic application surface 41 and the reflecting surface 511 opposite to the ultrasonic application surface 41 may also have concentric arc shapes with different diameters.
[0138] Furthermore, although the fluid device 10A of the second embodiment has a plurality of ultrasonic application surfaces 41 and a plurality of reflective surfaces 511 opposite to each ultrasonic application surface 41, the present invention is not limited thereto, and may also have a single ultrasonic application surface 41 and a reflective surface 511 opposite to the ultrasonic application surface 41.
[0139] Although in the first embodiment the reflecting surface 331, which serves as the flow channel wall, has a parabolic shape when viewed in YZ cross-section, and in the second embodiment the reflecting surface 511, which serves as the flow channel wall, has an arc shape when viewed in YZ cross-section, the present invention is not limited to these. That is, the reflecting surface 331 in the first embodiment or the reflecting surface 511 in the second embodiment only needs to be a structure with any concave curved surface shape.
[0140] This is a summary of the disclosure.
[0141] The fluid device according to a first aspect of the present invention comprises: a flow channel for the flow of fluid; an ultrasonic element for transmitting ultrasonic waves, serving as a flow channel wall, the flow channel having an ultrasonic application surface for applying the ultrasonic waves transmitted from the ultrasonic element to the fluid, and a reflective surface for reflecting the ultrasonic waves applied to the fluid from the ultrasonic application surface, the reflective surface having a concave curved shape.
[0142] According to this structure, ultrasonic waves reflected by the concave reflective surface generate constructive interference within the flow channel, thereby creating a region with strong sound pressure, which in turn enables the capture of particles. Therefore, a fluid device can be provided that can easily capture particles at desired locations without requiring the generation of a standing wave under stringent conditions.
[0143] In the fluid apparatus of the first embodiment, it is preferable that the reflecting surface, when viewed in cross-section at a surface intersecting with the flow direction of the fluid, has a parabolic shape that forms a focal point within the flow channel. In such a structure, the reflecting surface forms a linear focal point within the flow channel, and the ultrasonic waves reflected by the reflecting surface are concentrated at the linear focal point within the flow channel. This allows for the creation of an area with appropriately strong sound pressure near the linear focal point within the flow channel.
[0144] In the first type of fluid device, it is preferable that the ultrasonic wave application surface faces the reflecting surface. With this configuration, since the ultrasonic waves emitted from the ultrasonic wave application surface are easily incident along the parabolic axis of symmetry relative to the reflecting surface, the ultrasonic waves can be appropriately concentrated at a linear focal point within the flow channel.
[0145] In the first embodiment of the fluid apparatus, preferably, the ultrasonic wave applying surface and the reflecting surface face each other, and when viewed in cross-section at the surface where the ultrasonic wave applying surface and the reflecting surface intersect relative to the flow direction of the fluid, they have a concentric arc shape centered on an imaginary point within the flow channel. With this structure, by concentrating both the ultrasonic waves applied from the ultrasonic wave applying surface and the ultrasonic waves reflected by the reflecting surface near the imaginary point within the flow channel, a region with a strong sound pressure can be generated within the flow channel, thereby enabling the capture of particles in that region.
[0146] In the fluid apparatus of the first embodiment, it is preferable to include a plurality of ultrasonic elements, the flow channel having a plurality of ultrasonic application surfaces for applying ultrasonic waves from the plurality of ultrasonic elements to the fluid, and a plurality of reflecting surfaces respectively facing the plurality of ultrasonic application surfaces, wherein the plurality of ultrasonic application surfaces and the plurality of reflecting surfaces, when viewed in cross-section, have concentric arc shapes centered on a common imaginary point. With this structure, by concentrating the ultrasonic waves applied from the plurality of ultrasonic application surfaces and the ultrasonic waves reflected by the plurality of reflecting surfaces near the imaginary point within the flow channel, it is possible to generate a region within the flow channel where a stronger sound pressure is applied.
[0147] In the fluid apparatus of the first type, it is preferable that the phases of the ultrasonic waves transmitted from the plurality of ultrasonic elements are consistent with each other. According to this configuration, the ultrasonic waves concentrated near an imaginary point within the flow channel can appropriately generate constructive interference.
[0148] In the fluid device of the first embodiment, preferably, the flow channel has a circular cross-section, and when the diameter of the flow channel cross-section is set to D, the frequency of the ultrasonic wave is set to f, and the velocity of the ultrasonic wave is set to c, the width w of the ultrasonic wave application surface satisfies the following mathematical formula 16.
[0149] Mathematical formula 16
[0150]
[0151] With this structure, adjacent ultrasonic application surfaces do not negatively affect each other and can emit highly directional ultrasonic waves toward their corresponding reflecting surfaces. Therefore, it is possible to appropriately capture microparticles.
[0152] Symbol Explanation
[0153] 10, 10A…fluid device; 20, 20A…flow channel; 30…flow channel substrate; 31…bottom substrate; 311…groove; 32…encapsulation substrate; 33…wall; 331…reflective surface; 332…bottom; 40…ultrasonic application device; 41…ultrasonic application surface; 50…cylinder component; 51…inner circumferential surface; 511…reflective surface; 60…wall component; 61…ultrasonic application surface; C…central axis; D…flow channel diameter; F…focal point; FL…linear focal point; M…particle; R…convergence region; S…fluid; SL…symmetry axis; w…beam width.
Claims
1. A fluid device comprising: A flow channel, through which fluids circulate; Multiple ultrasonic elements that transmit ultrasonic waves. As the flow channel wall constituting the flow channel, the flow channel has a plurality of ultrasonic application surfaces that apply ultrasonic waves emitted from the plurality of ultrasonic elements to the fluid, and a plurality of reflective surfaces that face the plurality of ultrasonic application surfaces and reflect the ultrasonic waves applied to the fluid from the plurality of ultrasonic application surfaces. The reflective surface has a concave curved shape. When viewed in cross-section at the intersection of the plurality of ultrasonic application surfaces and the plurality of reflecting surfaces relative to the flow direction of the fluid, they have concentric arc shapes centered on the same imaginary point within the flow channel. The flow channel has a circular cross-section. When the diameter of the flow channel cross-section is set to D, the frequency of the ultrasonic wave is set to f, and the velocity of the ultrasonic wave is set to c, the width w of the ultrasonic wave application surface satisfies the following mathematical formula 1. Mathematical formula 1: 。 2. The fluid device as claimed in claim 1, wherein, The phases of the ultrasonic waves emitted from the plurality of ultrasonic elements are consistent with each other.