Method for driving fluid device, and fluid device

Abstract

To provide a method for driving a fluid device that suppresses diffusion of fine particles and achieves high capture efficiency, and to provide the fluid device.SOLUTION: Provided is a fluid device 10 comprising: an inflow passage 20 through which a fluid flows in a first direction; a separation passage 30 into which the fluid is introduced from the inflow passage and in which fine particles in the fluid are trapped using standing waves; a first outflow passage 40 through which a fluid having a high content of the trapped fine particles flows out from the separation passage; a second outflow passage 50 through which a fluid having a low content of the trapped fine particles flows out from the separation passage; a first ultrasonic element 61 that forms a first standing wave toward a second direction orthogonal to the first direction in the inflow passage; and a second ultrasonic element 62 that forms a second standing wave toward the second direction in the separation passage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for driving a fluidic device and a fluidic device. [Background technology]

[0002] Fluidic devices that acoustically focus particles in a fluid are known. For example, in the device disclosed in Patent Document 1, ultrasonic waves of a specific intensity, frequency, and phase, or a combination of these, are introduced into a container, and a position potential gradient is created by controlling the ultrasonic waves, thereby moving the particles. For example, standing waves are formed by ultrasonic waves, and particles are moved to the node positions of the standing waves. A capillary is introduced into the node positions and sucked in, allowing the particles to be collected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-122480 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the fluidic device disclosed in Patent Document 1 has a problem in that the concentration of particles dispersed in the container is insufficient, and particles are likely to be missed. For example, when a fluid is introduced from an inlet into a container in which a position potential gradient is formed by ultrasound, if the flow path diameters of the inlet and the container are different, the flow velocity component perpendicular to the flow path in the container increases, causing the particles to diffuse and reducing the capture efficiency. [Means for solving the problem]

[0005] A method for driving a fluidic device according to one aspect of the present disclosure includes an inlet flow channel through which a fluid flows in a first direction, a separation flow channel into which the fluid is introduced from the inlet flow channel and which captures particles in the fluid using standing waves, a first outlet flow channel through which the fluid with a high content of the captured particles flows out from the separation flow channel, a second outlet flow channel through which the fluid with a low content of the captured particles flows out from the separation flow channel, a first ultrasonic element disposed in the inlet flow channel to form a first standing wave in the inlet flow channel in a second direction perpendicular to the first direction, and a second ultrasonic element disposed in the separation flow channel to form a second standing wave in the separation flow channel in the second direction. and a second ultrasonic element that forms a standing wave, the method for driving a fluid device including the first ultrasonic element and the second ultrasonic element that form a standing wave, the method comprising: a reference setting step for setting a reference position of a node or antinode of the standing wave in the second direction; a first search step for searching for a first frequency of the standing wave at which a node or antinode is located within a predetermined tolerance range from the reference position; a second search step for searching for a second frequency of the second standing wave at which a node or antinode is located within the tolerance range from the reference position; and a drive step for driving the first ultrasonic element at the searched first frequency and driving the second ultrasonic element at the searched second frequency. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic diagram illustrating a fluidic device according to an embodiment of the present invention. [Figure 2] 10 is a flowchart showing a method for driving the fluidic device of the present embodiment. [Figure 3] FIG. 3 is an enlarged view of a connection portion between an inlet channel and a separation channel of the fluidic device of the present embodiment. [Figure 4] FIG. 10 is a diagram showing an example of the relationship between the drive frequency of an ultrasonic element and impedance. [Figure 5] FIG. 1 is a diagram showing the relationship between the frequency of an ultrasonic wave and the order of a standing wave. [Figure 6] 3 is a flowchart showing details of a method for determining a drive frequency in step S7 of FIG. 2. [Figure 7] 10 is a diagram showing the distance from the ultrasonic transmitting / receiving surface to the node position counted from the ultrasonic transmitting surface when the capture position is the node. FIG. [Figure 8] 10 is a diagram showing the distance from the ultrasonic transmitting / receiving surface to the position of the antinode counted from the ultrasonic transmitting surface when the capture position is the antinode. FIG. [Figure 9] FIG. 11 is a schematic diagram showing an example of a fluidic device according to a third modification. [Figure 10] FIG. 10 is a schematic diagram showing another example of a fluidic device according to Modification 3. [Figure 11] FIG. 10 is a schematic diagram showing an example of a fluidic device according to a fourth modification. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic diagram illustrating a fluidic device 10 according to this embodiment. As shown in FIG. 1, the fluidic device 10 includes an inlet channel 20, a separation channel 30, a first outlet channel 40, a second outlet channel 50, an ultrasonic transmitter 60, and a controller 70.

[0008] The fluidic device 10 of this embodiment acoustically focuses particles in a fluid flowing from the inlet channel 20 to the separation channel 30, and allows the fluid with concentrated particles to flow out from the first outlet channel 40, while allowing the fluid with diluted or removed particles to flow out from the second outlet channel 50. The fluid is not particularly limited, and may be any liquid such as water. The particles are not particularly limited, and may be, for example, microfibers or microplastics.

[0009] In this embodiment, the inlet flow channel 20, the separation flow channel 30, the first outlet flow channel 40, and the second outlet flow channel 50 are arranged along an arbitrary direction, and allow fluid to flow along that direction. Here, the flow direction of the fluid in each flow channel (first direction in the present disclosure) is defined as the X direction, the upstream side of the flow direction of the fluid is defined as the -X side, and the downstream side of the flow direction of the fluid is defined as the +X side. Furthermore, a direction perpendicular to the X direction and in which standing waves SW1 to SW3 (described below) are formed (second direction in the present disclosure) is defined as the Y direction, one side of the Y direction is defined as the -Y side, and the other side of the Y direction is defined as the +Y side. Furthermore, the directions perpendicular to the X direction and the Y direction are defined as the Z direction.

[0010] In this embodiment, the entire flow path including the inlet flow path 20, the separation flow path 30, the first outlet flow path 40, and the second outlet flow path 50 is mainly formed by the flow path member 11. The flow path member 11 is made of a material that can reflect ultrasonic waves in the fluid, for example, a material that has an acoustic impedance different from that of the fluid.

[0011] The inflow channel 20 is a channel that allows a fluid containing fine particles to flow into the separation channel 30. An inlet pipe (not shown) that introduces a fluid into the fluidic device 10 is connected to the −X side end of the inflow channel 20, and the +X side end of the inflow channel 20 is connected to the −X side end of the separation channel 30. The channel width L1 in the Y direction of the inflow channel 20 is defined by a pair of flat wall surfaces 21 and 22 that face each other in the Y direction.

[0012] The separation channel 30 is an intermediate channel that allows the fluid that has flowed in from the inlet channel 20 to flow out to each of the first outlet channel 40 and the second outlet channel 50. The channel width L2 of the separation channel 30 in the Y direction is determined by a pair of flat wall surfaces 31, 32 that face each other in the Y direction. The channel width L2 of the separation channel 30 is greater than the channel width L1 of the inlet channel 20. In addition, the wall surface 31 on the -Y side of the separation channel 30 is continuous with the wall surface 21 on the -Y side of the inlet channel 20 in the X direction.

[0013] The first outlet channel 40 and the second outlet channel 50 are channels for discharging the fluid from the separation channel 30, and are connected in parallel to each other in the Y direction with respect to the +X side end of the separation channel 30.

[0014] The first outlet flow path 40 is disposed at a position opposite to the inlet flow path 20 in the X direction across the separation flow path 30. In other words, the Y direction range in which the inlet flow path 20 is disposed is included in the Y direction range in which the first outlet flow path 40 is disposed. In addition, the +X side end of the first outflow channel 40 forms a concentration port 43 through which the fluid flowing in from the separation channel 30 flows out. The channel width L3 of the first outflow channel 40 in the Y direction is defined by a pair of flat wall surfaces 41 and 42 facing each other in the Y direction. The channel width L3 of the first outflow channel 40 is larger than the channel width L1 of the inflow channel 20 and smaller than the channel width L2 of the separation channel 30. Also, the -Y side wall surface 41 of the first outflow channel 40 is continuously connected to the -Y side wall surface 31 of the separation channel 30 in the X direction. In this embodiment, an example where L1 < L3 is shown, but it is not limited to this. Although details will be described later, in this embodiment, the fine particles in the fluid are captured at the node or antinode positions of the standing wave in the Y direction and are flowed downstream while substantially maintaining the capture positions. Therefore, for example, the channel width L3 of the first outflow channel 40 may be configured to have the same width as the channel width L1 of the inflow channel 20, or may be configured to have a width smaller than the channel width L1 of the inflow channel 20. In particular, by making the frequency of the ultrasonic wave output from the second ultrasonic element 62 larger than the frequency of the ultrasonic wave of the first ultrasonic element 61, the movement of the fine particles in the Y direction can be suppressed.

[0015] The second outflow channel 50 is arranged on the +Y side of the first outflow channel 40. Also, the +X side end of the second outflow channel 50 forms a purification port 53 through which the fluid flowing in from the separation channel 30 flows out. The channel width L4 of the second outflow channel 50 is defined by a pair of flat wall surfaces 51 and 52 facing each other in the Y direction.

[0016] The space between the first outflow channel 40 and the second outflow channel 50 is partitioned by a partition portion 112. In other words, the channel member 11 has a partition portion 112 that partitions the space between the first outflow channel 40 and the second outflow channel 50. This partition portion 112 forms the +Y side wall surface 42 of the first outflow channel 40 and the -Y side wall surface 51 of the second outflow channel 50. In this embodiment, it is assumed that the total dimension obtained by adding the channel width L3 of the first outflow channel 40, the channel width L4 of the second outflow channel, and the dimension of the partition portion 112 in the Y direction is equal to the channel width L2 of the separation channel 30.

[0017] The ultrasonic transmission unit 60 includes a first ultrasonic element 61 arranged in the inflow channel 20, a second ultrasonic element 62 arranged in the separation channel 30, and a third ultrasonic element 63 arranged in the first outflow channel 40. The ultrasonic transmission unit 60 also includes a first drive circuit 64 that controls the drive of the first ultrasonic element 61, a second drive circuit 65 that controls the drive of the second ultrasonic element 62, and a third drive circuit 66 that controls the drive of the third ultrasonic element 63. In this embodiment, the ultrasonic transmission surface of the first ultrasonic element 61 forms part of the wall surface 21 of the inflow channel 20. The ultrasonic transmission surface of the second ultrasonic element 62 forms part of the wall surface 31 of the separation channel 30. The ultrasonic transmission surface of the third ultrasonic element 63 forms part of the wall surface 41 of the first outflow channel 40. In this embodiment, an example is shown in which the transmitting and receiving surfaces of the first ultrasonic element 61, the second ultrasonic element 62, and the third ultrasonic element 63 configure the wall surfaces 21, 31, and 41, respectively, but the present invention is not limited to this, and at least one of the first ultrasonic element 61, the second ultrasonic element 62, and the third ultrasonic element 63 may be disposed outside the wall surfaces 21, 31, and 41. In this case, a configuration may be adopted in which ultrasonic waves are propagated into the fluid via the wall surfaces 21, 31, and 41.

[0018] The specific configuration of each of the ultrasonic elements 61, 62, and 63 of the ultrasonic transmission unit 60 is not particularly limited. For example, the ultrasonic elements 61, 62, and 63 may be bulk ultrasonic elements or thin-film ultrasonic elements. A bulk ultrasonic element is an element that vibrates a bulk piezoelectric body in response to an input signal and outputs ultrasonic waves due to the vibration of the piezoelectric body. A thin-film ultrasonic element is an element that includes a substrate with one or more openings formed therein, a thin-film vibration part that covers each opening of the substrate, and a piezoelectric film disposed on each vibration part. The piezoelectric film is expanded and contracted in response to an input signal, causing the vibration part to vibrate, and ultrasonic waves are output due to the vibration of the vibration part.

[0019] In this embodiment, the ultrasonic waves transmitted from the first ultrasonic element 61 form a first standing wave SW1 in the Y direction in the inflow channel 20. The ultrasonic waves transmitted from the second ultrasonic element 62 form a second standing wave SW2 in the Y direction in the separation channel 30. The ultrasonic waves transmitted from the third ultrasonic element 63 form a third standing wave SW3 in the Y direction in the first outflow channel 40. The first ultrasonic element 61, the second ultrasonic element 62, and the third ultrasonic element 63 are provided so as to be able to change the frequency of the ultrasonic waves they transmit.

[0020] The first drive circuit 64 causes the first ultrasonic element 61 to output ultrasonic waves to form a first standing wave SW1 based on the control of the control unit 70. Furthermore, the first drive circuit 64 changes the frequency (first frequency) of the ultrasonic waves output from the first ultrasonic element 61 to change the order (positions of the antinodes and nodes) of the first standing wave SW1. Similarly, the second drive circuit 65 causes the second ultrasonic element 62 to output ultrasonic waves to form a second standing wave SW2 based on the control of the control unit 70. Furthermore, the second drive circuit 65 changes the frequency (second frequency) of the ultrasonic waves output from the second ultrasonic element 62, thereby changing the order (positions of the antinodes and nodes) of the second standing wave SW2. Similarly, the third drive circuit 66 causes the third ultrasonic element 63 to output ultrasonic waves to form a third standing wave SW3 based on the control of the control unit 70. Furthermore, the third drive circuit 66 changes the frequency (third frequency) of the ultrasonic waves output from the third ultrasonic element 63 to change the order (positions of the antinodes and nodes) of the third standing wave SW3. In FIG. 1, the nodes of the standing waves SW1 to SW3 are shown as dotted lines (lines parallel to the X direction), and the particles in the fluid are shown as black circles.

[0021] As described above, the control unit 70 controls the driving of the first ultrasonic element 61, the second ultrasonic element 62, and the third ultrasonic element 63 via the first drive circuit 64, the second drive circuit 65, and the third drive circuit 66. The control unit 70 is configured by a general computer, and as shown in FIG. 1, includes a memory unit 71 that stores programs and various data, and a processor 72 that realizes predetermined functions by reading and executing the programs stored in the memory unit 71. The processor 72 reads and executes the programs stored in the storage unit 71, thereby functioning as a reference setting unit 721, a frequency search unit 722, and an ultrasound control unit 723, as shown in FIG.

[0022] The reference setting unit 721 sets a position in the Y direction (reference position) where particles in the fluid are to be captured. The reference position may be obtained by acquiring a position input by a user, or may be set by storing the reference position in advance in the storage unit 71 and having the reference setting unit 721 read the reference position from the storage unit 71.

[0023] The frequency search unit 722 sets the frequencies of the standing waves SW1, SW2, and SW3 that have nodes or antinodes that capture particles within a predetermined allowable range from the reference position. The frequency search unit 722 individually sets the frequencies of the first ultrasonic element 61, the second ultrasonic element 62, and the third ultrasonic element 63. The frequency search unit 722 searches for a first frequency of the first standing wave SW1 at which the difference (first deviation) between the position of a node or antinode of the first standing wave SW1 formed by the first ultrasonic element 61 and a reference position is equal to or less than a predetermined first reference deviation E1. If there are multiple frequencies at which the first deviation is equal to or less than the first reference deviation E1, for example, the frequency at which the order of the first standing wave SW1 is smallest may be set as the first frequency, or the frequency of the first standing wave SW1 at which the first deviation is smallest may be set as the first frequency. The first reference deviation amount may be a value arbitrarily set by the user, for example. That is, the first reference deviation amount is a value indicating to what extent the particle capture position is allowed to deviate from the reference position.

[0024] Furthermore, the frequency search unit 722 searches for a second frequency of the second standing wave SW2 at which the difference (second deviation) between the position of the node or antinode of the second standing wave SW2 formed by the second ultrasonic element 62 and the position of the antinode or node of the first standing wave SW1 is equal to or less than a predetermined second reference deviation E2. If there are multiple frequencies at which the second deviation is equal to or less than the second reference deviation E2, for example, the frequency at which the order of the second standing wave SW2 is smallest may be set as the second frequency, or the frequency of the second standing wave SW2 at which the second deviation is smallest may be set as the second frequency. The second reference deviation amount E2 is preferably set based on the wavelength (first wavelength λ1) of the ultrasonic waves forming the first standing wave SW1. That is, in this embodiment, when a particle captured at a node or antinode of the first standing wave SW1 in the inflow channel 20 flows into the separation channel 30 with the flow of fluid, the particle continues to be captured at approximately the same position in the Y direction. Therefore, it is preferable to position the node or antinode of the first standing wave SW1 and the second standing wave SW2 as close as possible. If the node or antinode of the second standing wave SW2 is λ1 / 8 or more relative to the position in the Y direction of the node or antinode of the first standing wave SW1, for example, there is a high possibility that the node of the first standing wave SW1 will be located near the antinode of the second standing wave SW2 in the Y direction. Therefore, it is preferable to form the second standing wave SW2 so that the node or antinode of the second standing wave SW2 is located at a position that is less than λ1 / 8 relative to the node or antinode position near the reference position of the first standing wave SW1, more preferably, so that the node or antinode of the second standing wave SW2 is located at a position that is less than λ1 / 10 relative to the node or antinode position near the reference position of the first standing wave SW1. Therefore, in this embodiment, the second reference shift amount E2 is set to E2=0.1λ1. As a result, the node position of the second standing wave SW2 becomes approximately the same as the node position of the first standing wave SW1 in the Y direction.

[0025] Furthermore, the frequency search unit 722 searches for a third frequency of the third standing wave SW3 at which the difference (third deviation amount) between the position of the node or antinode of the third standing wave SW3 formed by the third ultrasonic element 63 and the position of the antinode or node of the second standing wave SW2 is equal to or less than a predetermined third reference deviation amount E3. If there are multiple frequencies at which the third deviation amount is equal to or less than the third reference deviation amount E3, for example, the frequency at which the order of the third standing wave SW3 is smallest may be set as the third frequency, or the frequency of the third standing wave SW3 at which the third deviation amount is smallest may be set as the third frequency. The third reference shift amount E3 is set in the same way as the second reference shift amount E2 for the first wavelength λ1. That is, E3 = 0.1λ2 is set based on the wavelength (second wavelength λ2) of the ultrasonic waves that form the second standing wave SW2. As a result, the node positions of the third standing wave SW3 in the Y direction are approximately the same as the node positions of the second standing wave SW2.

[0026] The ultrasonic control unit 723 drives the ultrasonic elements 61, 62, and 63 at the frequency searched and determined by the frequency search unit 722.

[0027] [Operation of fluidic device 10] Next, a method for driving the fluidic device 10 of this embodiment will be described. FIG. 2 is a flowchart showing a method for driving the fluidic device 10 of this embodiment. In the fluidic device 10 of this embodiment, it is determined whether the acoustic factor of the particle to be trapped in the fluid is positive (step S1). The acoustic factor is determined by the density ratio and compressibility ratio between the medium in the sound field and the particle. If the acoustic factor is positive, the particle is trapped at the node position of the standing waves SW1, SW2, and SW3, and if the acoustic factor is negative, the particle is trapped at the antinode position of the standing waves SW1, SW2, and SW3. The control unit 70 determines whether the acoustic factor is positive or negative based on an input operation by the user.

[0028] For example, when the user inputs that the acoustic factor is positive, the control unit 70 determines YES in step S1 and sets the capture variable K to K=2k−1 (step S2). On the other hand, if the user inputs that the acoustic factor is negative, the control unit 70 determines NO in step S1 and sets the capture variable K to K=2k (step S3). This capture variable K is a variable that indicates the position of a node or antinode counted from the ultrasonic transmission surface of the ultrasonic transmission unit 60. K=2k-1 indicates the position of a node when the positions of the nodes or antinodes of the standing waves SW1, SW2, and SW3 are counted in order from the ultrasonic transmission surface. K=2k indicates the position of an antinode when the positions of the nodes or antinodes of the standing waves SW1, SW2, and SW3 are counted in order from the ultrasonic transmission surface.

[0029] Next, the reference setting unit 721 of the control unit 70 sets the reference position y l is set (step S4). 3 is an enlarged view of the connection portion between the inflow channel 20 and the separation channel 30 of the fluidic device 10 of this embodiment. In FIG. 3, the dashed line indicates the reference position y l 3, the broken lines indicate the node positions of the first standing wave SW1 and the second standing wave SW2. In the example of FIG. 3, the acoustic factor is positive, and the particles are captured at the node positions. Reference position y l As described above, the reference position y is an approximate position where the particles contained in the fluid are converged in the fluidic device 10, and can be arbitrarily set by the user. l As described above, the setting of the reference position y l may be acquired, and the reference position y l You can also set it by reading

[0030] Next, the frequency search unit 722 searches for the frequencies of the ultrasonic elements 61, 62, and 63. To do this, first, the frequency search unit 722 initializes the element variable x indicating the ultrasonic elements 61, 62, and 63 to x = 1 (step S5). Note that x = 1 indicates the first ultrasonic element 61, x = 2 indicates the second ultrasonic element 62, and x = 3 indicates the third ultrasonic element 63.

[0031] The frequency search unit 722 performs frequency sweep on the ultrasonic element corresponding to the element variable x, measures the impedance in the ultrasonic element, and identifies a plurality of frequencies at which a standing wave can be formed (step S6). FIG. 4 is a diagram showing an example of the relationship between the drive frequency of the ultrasonic element and the impedance. When a standing wave is formed in a flow path, the position of the ultrasonic transmission surface of the ultrasonic element becomes the antinode, and the impedance of the ultrasonic element becomes a local maximum. Therefore, by measuring the impedance and identifying the frequency at which the local maximum value is reached, it is possible to identify the frequency at which the standing wave is formed. In Figure 4, n indicates the order, and f x,n indicates the frequency of the ultrasonic wave when the ultrasonic element corresponding to the element variable x forms a standing wave of order n. In an actual fluidic device 10, there is a limit to the variable range of the frequency of the ultrasonic waves that can be transmitted by the ultrasonic element, and there is also a limit to the order of the standing wave that can be formed, but here, for the sake of simplicity, an example is shown in which a standing wave can be formed from a first-order standing wave.

[0032] For example, when x=1, ultrasonic waves are transmitted from the first ultrasonic element 61, and the frequency of the ultrasonic waves is swept to measure the impedance of the first ultrasonic element 61. When the first standing wave SW1 is formed in the inflow flow path 20, the impedance of the first ultrasonic element 61 becomes a maximum value. Therefore, by sweeping the frequency of the first ultrasonic element 61, the impedance of the first ultrasonic element 61 becomes a maximum value. 1,n can be identified. When determining whether or not a standing wave is formed by measuring impedance, it is preferable to use thin-film ultrasonic elements as the ultrasonic elements 61, 62, and 63. When using bulk ultrasonic elements, a pressure sensor (or a strain sensor) for measuring the sound pressure of ultrasonic waves is provided on the wall surfaces 21, 31, and 41, and the frequency f of ultrasonic waves at which the pressure measured by the pressure sensor reaches a maximum value is determined. x,n It is sufficient to identify the following.

[0033] Figure 5 shows the ultrasonic frequency f x,n and the order n of the standing wave. The ultrasonic frequency f that can form a standing wave x,n The relationship between the modal order and the modal frequency is as shown in the following equation (1), and is proportional to the modal frequency as shown in FIG.

[0034]

number

[0035] In equation (1), c0 represents the speed of sound in the fluid. Lx is the channel width of the fluidic device 10 at the ultrasonic element with element variable x. When x=1 representing the first ultrasonic element 61, it represents the channel width L1 of the inflow channel 20. When x=2 representing the second ultrasonic element 62, it represents the channel width L2 of the separation channel 30. When x=3 representing the third ultrasonic element 63, it represents the channel width L3 of the first outflow channel 40. In this embodiment, the frequency search unit 722 searches for ultrasonic frequencies f that can form standing waves SW1, SW2, and SW3 in each of the ultrasonic elements 61, 62, and 63. x,n and the orders of the standing waves SW1, SW2, and SW3 when the ultrasonic elements 61, 62, and 63 are driven at frequencies fx and n.

[0036] Next, the actual drive frequency of the ultrasonic element for the element variable x is determined from each frequency of the ultrasonic wave capable of forming a standing wave measured in step S6 (step S7). FIG. 6 is a flowchart showing the details of the method for determining the drive frequency in step S7. First, the frequency search unit 722 initializes the order n to the minimum value (step S21). In this embodiment, for the sake of simplicity, the minimum value is set to n=1. Next, the frequency search unit 722 searches for the wavelength λ of the ultrasonic wave for forming the standing wave of order n. x,n (Step S22). x,n can be calculated using the following formula (2).

[0037]

number

[0038] Next, the position y of the node or antinode that can capture the particle from the ultrasonic transmission surface of the ultrasonic element is calculated. lx,n is calculated (step S23). When the trapping variable K is obtained in step S2, the position of the node corresponding to K=2k-1 (k=1, 2, 3...) is the position where the particle can be trapped. Also, when the trapping variable K is obtained in step S3, the position of the antinode corresponding to K=2k (k=1, 2, 3...) is the position where the particle can be trapped. FIG. 7 is a diagram showing the distance from the ultrasonic wave transmitting surface to the position of the node counted from the ultrasonic wave transmitting surface when the capture position is the node. FIG. 8 is a diagram showing the distance from the ultrasonic wave transmission surface to the position of the antinode counted from the ultrasonic wave transmission surface when the capture position is the antinode. That is, the frequency search unit 722 searches for the node or antinode position y lx,n and calculate it using the following formula (3).

[0039]

number

[0040] The frequency search unit 722 sequentially substitutes k=1, 2, 3, . . . into equation (3) to find each position y lx,n Calculate the reference position y l The closest position to y lx,n (Step S24). The reference position y l The node or antinode closest to is assumed to be the kxth node. Next, the frequency search unit 722 determines whether or not x>1 (step S25), and if NO (x=1), sets the allowable deviation amount E to the first reference deviation amount E1 (step S26). On the other hand, if the answer to step S25 is YES (x>1), the frequency search unit 722 sets the allowable deviation E to E=0.1λ x-1,n That is, in the frequency setting of the second ultrasonic element 62, the allowable deviation E is set as follows: E=E2=0.1λ 1,nIn the frequency setting of the third ultrasonic element 63, the allowable deviation E is E=E3=0.1λ 2,n As described above, E2 is the second reference deviation amount, and E3 is the third reference deviation amount.

[0041] After that, the frequency search unit 722 searches for the reference position y l The node or antinode position closest to y lx,n and the reference position y l It is determined whether the absolute value of the difference between is less than the allowable deviation amount E (step S28). If the determination in step S28 is NO, 1 is added to the degree n (step S29), and the process returns to step S22. If the determination in step S28 is YES, the frequency search unit 722 searches for the drive frequency f x As, f x,n That is, if the determination in step S28 is YES, the order n of the standing wave to be formed is determined, and the wavelength λ of the standing wave is adopted (step S30). x is the wavelength λ x,n Also, the position y of the node (or antinode) closest to the reference position yl is determined as lx,n is the trapping position of the particle in the standing wave formed by the ultrasonic element corresponding to the element variable x. l At this capture position y lx,n (Step S31). As a result, in the loop where the element variable is x+1, the capture position y corresponding to the determined element variable x is updated to lx,n A search for a drive frequency is performed based on the above.

[0042] After the above, the frequency search unit 722 determines whether the element variable x is at the maximum value (step S8). If the determination in step S8 is NO, 1 is added to the element variable x (step S9), and the process returns to step S6. If the determination in step S8 is YES, the search process ends, and the ultrasonic control unit 723 drives the ultrasonic transmission unit 60 (step S10). That is, the ultrasonic control unit 723 drives the first ultrasonic element 61 at the set drive frequency f1, drives the second ultrasonic element 62 at the drive frequency f2, and drives the third ultrasonic element 63 at the drive frequency f3.

[0043] As a result, the reference position y l The particles are captured at a capture position within a predetermined tolerance range (within the range of E1 + E2 + E3) from the inlet flow path 20, the separation flow path 30, and the first outlet flow path 40, and the outflow of the particles into the second outlet flow path 50 is suppressed.

[0044] [Effects of this embodiment] The fluidic device 10 of this embodiment includes an inflow channel 20 through which a fluid flows in the X direction (first direction), a separation channel 30 into which a fluid is introduced from the inflow channel 20, a first outflow channel 40 through which a fluid with a high content of fine particles flows out from the separation channel 30, a second outflow channel 50 through which a fluid with a low content of fine particles flows out from the separation channel 30, and a control unit 70. The inflow channel 20 is provided with a first ultrasonic element 61 that forms a first standing wave SW1 in the Y direction (second direction) perpendicular to the X direction. The separation channel 30 is provided with a second ultrasonic element 62 that forms a second standing wave SW2 in the separation channel 30 in the Y direction. The control unit 70 controls the reference position y of a node or antinode of the standing wave in the Y direction. l a reference setting step (step S4) for setting the reference position y l The first frequency f of the first standing wave SW1, at which a node or antinode is located within a predetermined tolerance range from l1,n The first search step (step S7 in the loop where x=1) searches for the reference position y l A second frequency f of the second standing wave SW2 having a node or antinode located within the tolerance range l2,n A second search step (step S7 in the loop with x=2) searches for the first frequency f l1,n The first ultrasonic element 61 is driven at the second frequency f l2,nThen, a driving step (step S10) of driving the second ultrasonic element 62 is performed.

[0045] As a result, the behavior of the particle immediately before the particle is captured at the node or antinode of the second standing wave SW2 in the separation channel 30 can be controlled by the first standing wave SW1 formed by the first ultrasonic element 61, and the particle capture efficiency can be improved. l The particles captured at the nodes or antinodes of the first standing wave SW1 within the allowable range from the reference position y l Therefore, when the fluid flows from the inlet channel 20 into the separation channel 30, a velocity component of the fluid in the Y direction is generated. l The first standing wave SW1 is captured at a node or antinode of the first standing wave SW1 within the allowable range from the reference position y l Therefore, the movement of the particles in the Y direction is restricted, which suppresses diffusion, improves the efficiency of capturing the particles, and allows a fluid with a high concentration of particles to flow out of the first outlet flow path 40.

[0046] Furthermore, mass-produced fluidic devices 10 typically contain minute errors during manufacturing. When using ultrasonic elements with fixed frequencies, it is difficult to form appropriate standing waves for the channel width of the fluidic device, which contains manufacturing errors. It is possible to measure the channel width after manufacturing for each individual fluidic device and set the driving frequency of the ultrasonic element, but this increases the manufacturing cost. Furthermore, the channel width of the fluidic device 10 may vary depending on the usage environment or aging, in which case maintenance or replacement is required to form appropriate standing waves. In contrast, in this embodiment, a first frequency f that can form standing waves SW1 and SW2 is set regardless of the channel width of the fluidic device 10, and even if the channel width varies depending on the usage environment or aging. l1,n , and the second frequency f l2,ncan be searched, whereby the capture efficiency of the fine particles can be improved and the decrease in the capture efficiency can be suppressed.

[0047] In the fluid device 10 of the present embodiment, in step S7 (the loop with x = 1), the position of the node or antinode of the first standing wave SW1 and the reference position y l The first displacement amount (|y l1,n ― y l |) is calculated, and based on the difference between the first displacement amount and a predetermined first reference displacement amount E1, the first frequency f l1,n is searched. That is, the first frequency f l1,n ― y l | < E1 is satisfied, and the first frequency f l1,n is searched. Thereby, the first frequency f l that can form the first standing wave SW1 in which the position of the node or antinode appears at a position close to the set reference position y l1,n can be searched.

[0048] In the fluid device 10 of the present embodiment, the capture position y l1,n of the node or antinode close to the reference position y l formed by the first standing wave SW1 formed at the searched first frequency f l1,n is set as a new reference position y l . Then, in step S7 (the loop with x = 2), the displacement amount of the position of the node or antinode of the second standing wave SW2 and the newly set reference position y l (that is, the capture position y l1,n of the first standing wave SW1 formed at the searched first frequency f l1,n ) is the second displacement amount |y l2,n -y l | (= |y l2,n -y <00​​​​​​​​​​As a result, a second frequency f that can form a second standing wave SW2 having a node or antinode position appearing at a position close to the capture position where the particle is captured by the first standing wave SW1 is generated. l2,n can be explored.

[0049] In the fluidic device 10 of this embodiment, the second reference deviation amount E2 is set to the wavelength λ of the ultrasonic wave that forms the first standing wave SW1. 1,n It is set based on That is, the nodes and antinodes of the first standing wave SW1 are λ 1,n / 8 interval, the capture position of the particle by the second standing wave SW2 is y l2,n is the capture position y of the particle by at least the first standing wave SW1. l1,n For λ 1,n In this embodiment, the wavelength λ of the ultrasonic wave forming the first standing wave SW1 is preferably within a range of λ / 8. 1,n Using E2=0.1λ 1,n By doing so, the particle capture position y l1,n and the capture position y of the particle by the second standing wave SW2. l2,n and can be brought close to each other, and the second standing wave SW2 can be formed so as to suppress the diffusion of the particles when they flow from the inflow channel 20 into the separation channel 30.

[0050] In the fluidic device 10 of this embodiment, the second displacement amount (|y l2,n -y l If |) is greater than the second reference deviation amount E2, in step S29, the order n of the second standing wave SW2 is increased to obtain the second frequency f l2,n Explore. By increasing the order n of the second standing wave SW2, the second standing wave SW2 can be formed with a small node or antinode interval. l1,n Therefore, the second standing wave SW2 having a node or antinode close to the point SW2 can be efficiently searched for.

[0051] The fluidic device 10 of this embodiment further includes a third ultrasonic element 63 that forms a third standing wave SW3 in the Y direction in the first outflow channel 40. The control unit 70 then lto within an allowable range, the third frequency f of the third standing wave SW3 at which a node or an antinode is located l3,n A third search step (step S7 in the loop with x = 3) of searching for is further performed. In step S10, the searched third frequency f l3,n is used to drive the third ultrasonic element 63 As a result, the fine particles captured at the node or antinode position of the second standing wave SW2 in the separation channel 30 are directly captured at the node or antinode position of the third standing wave SW3 in the first outflow channel 40 and flow in the X direction. Therefore, it is possible to suppress the inconvenience that the fine particles diffuse in the first outflow channel 40 and the diffused fine particles return to the separation channel 30, and it is possible to improve the capture efficiency of the fine particles Also, similar to the first standing wave SW1 and the second standing wave SW2, even when the channel width L3 of the first outflow channel 40 includes a manufacturing error or the channel width L3 fluctuates due to the use environment or aging, it is possible to search for the third frequency that forms an appropriate third standing wave SW3 capable of capturing fine particles

[0052] In the fluid device 10 of the present embodiment, at the second standing wave SW2 formed at the searched second frequency f l2,n a node or antinode position (capture position y l ) close to the reference position y l2,n is set as a new reference position y l . Then, in step S7 (loop with x = 3), the difference between the node or antinode position of the third standing wave SW3 and the newly set reference position y l (that is, the capture position y of the second standing wave SW2 formed at the searched second frequency f l2,n ) is calculated as the third deviation amount (|y l2,k - y l3,n | = |y l - y l3,n |). Based on the difference between the third deviation amount and a predetermined third reference deviation amount E3, the third frequency f l3,n is searched for That is, a third frequency f l3,n satisfying |y l3,n - y l | < E3 is searched for l3,n As a result, the capture position y for capturing fine particles with the second standing wave SW2​l2,n A third frequency f that can form a third standing wave SW3 in which a node or antinode appears at a position close to l3,n can be explored.

[0053] In the fluidic device 10 of this embodiment, the third reference deviation amount E3 is set to the wavelength λ of the ultrasonic wave that forms the second standing wave SW2. 2,n That is, the wavelength λ of the ultrasonic wave that forms the second standing wave SW2 is set based on 2,n Using E3=0.1λ 2,n Let's say. As a result, the particle capture position y l2,n and the capture position y of the particle by the third standing wave SW3. l3,n and can be placed close to each other, and the third standing wave SW3 can be formed so as to suppress the diffusion of the particles when they flow from the separation channel 30 into the first outlet channel 40.

[0054] [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.

[0055] [Variation 1] In the above embodiment, an example is shown in which the fluid device 10 is provided with an ultrasonic transmitting unit 60 including a first ultrasonic element 61, a second ultrasonic element 62, and a third ultrasonic element 63, but the third ultrasonic element 63 does not have to be provided. In other words, even if the third ultrasonic element 63 is not provided, the particles move from the inlet channel 20 to the separation channel 30 at the reference position y l The ultrasonic wave is captured at a capture position (node ​​or antinode) located within a predetermined tolerance range from the first ultrasonic element 63, and moves along with the flow of the fluid to the first outlet flow path 40. Therefore, the third ultrasonic element 63 is not necessarily required. Furthermore, as in the above embodiment, by providing the third ultrasonic element 63, the movement of particles in the Y direction within the first outflow flow path 40 is suppressed, thereby preventing the inconvenience of particles that have moved from the first outflow flow path 40 to the +Y side flowing back into the separation flow path 30.

[0056] [Variation 2] In the above embodiment, in steps S25 to S28, the particle capture position y lx,n and the reference position y l Although it is determined whether the absolute value of the difference between is less than the allowable deviation amount E, the present invention is not limited to this. For example, y l -y lx,n >Frequency f where E x,n The driving frequency f x In this case, the particle capture position y at the node (or antinode) of the first standing wave SW1 in the inflow channel 20 may be l1,n On the other hand, the trapping position y of the particle at the node (or antinode) of the second standing wave SW2 in the separation channel 30 l2,n is located closer to the -Y side. The movement of the particles from the separation channel 30 to the first outlet channel 40 is similar, moving closer to the -Y side. Therefore, when the particles move from the inlet channel 20, through the separation channel 30, to the first outlet channel 40, they flow to the side away from the second outlet channel 50. This makes it possible to further suppress the problem of the particles flowing to the +Y side (the second outlet channel 50 side), and to increase the concentration of particles in the fluid flowing out of the first outlet channel 40.

[0057] [Variation 3] In the above embodiment, an example was shown in which the first ultrasonic element 61, the second ultrasonic element 62, and the third ultrasonic element 63 are all arranged on the -Y side of the flow channel, but at least one of them may be located on the +Y side. Fig. 9 is a schematic diagram showing an example of a fluidic device 10A according to Modification 3. Note that the first drive circuit 64, the second drive circuit 65, the third drive circuit 66, and the control unit 70 are not shown in Fig. 9. 9, the first ultrasonic element 61 may be provided on the wall surface 22 on the +Y side of the inflow channel 20. The second ultrasonic element 62 may be provided on the wall surface 32 on the +Y side of the separation channel 30. The third ultrasonic element 63 may be provided on the wall surface 42 on the +Y side of the first outflow channel 40. In FIG. 9, the first ultrasonic element 61, the second ultrasonic element 62, and the third ultrasonic element 63 are all arranged on the +Y side of the flow path, but it is also possible to configure at least one of them to be arranged on the +Y side of the flow path and the rest to be arranged on the -Y side.

[0058] Furthermore, at least one of the first ultrasonic element 61, the second ultrasonic element 62, and the third ultrasonic element 63 may be configured to be provided on both the ±Y sides of the flow channel. FIG. 10 is a diagram showing another example of a fluidic device 10B according to the third modification. 10, first ultrasonic elements 61A and 61B may be provided on the wall surfaces 21 and 22 on the ±Y sides of the inflow channel 20. In this case, the first ultrasonic element 61A and the first ultrasonic element 61B are driven at the same drive frequency f1, and the drive periods of the first ultrasonic element 61A and the first ultrasonic element 61B are shifted by half a period to form a first standing wave SW1. The same applies to the second ultrasonic elements 62A and 62B and the third ultrasonic elements 63A and 63B.

[0059] [Variation 4] Furthermore, in the above embodiment, a configuration in which the -Y side wall surface 21 of the inlet flow path 20, the -Y side wall surface 31 of the separation flow path 30, and the -Y side wall surface 41 of the first outlet flow path 40 are continuous is exemplified, but this is not limited to this. FIG. 11 is a diagram showing an example of a fluidic device 10C according to the fourth modification. 11, the inflow channel 20A may be connected to the center of the separation channel 30A. In this case, the first outflow channel 40A is connected to the center of the separation channel 30A, facing the inflow channel 20A. In order to make the flow distribution in the Y direction in the separation channel 30A symmetrical, it is preferable to provide second outflow channels 50A with the same channel diameter on each of the ±Y sides of the first outflow channel 40A. 11, the first ultrasonic element 61 is provided on the -Y side of the inflow channel 20A, the second ultrasonic element 62 is provided on the -Y side of the separation channel 30A, and the third ultrasonic element 63 is provided on the -Y side of the first outflow channel 40, but this is not limiting. As explained in the above-mentioned modified example 3, the ultrasonic elements 61, 62, 63 may be arranged on the +Y side of each channel, or may be arranged on both the ±Y sides.

[0060] [Variation 5] In the above embodiment, an upper limit may be set for the drive frequency of each of the ultrasonic elements 61, 62, and 63. For example, when microfibers are used as the particles, the frequency of each of the ultrasonic elements 61, 62, and 63 is set to be equal to or less than (sound speed in the fluid) / (4×fiber length). In this case, the fiber length direction of the microfibers can be made approximately parallel to the X direction in which the fluid flows, and clogging of the microfibers in the flow path can be suppressed. Furthermore, when separating microfibers as fine particles, it is preferable to set the drive frequency f2 of the second ultrasonic element 62 corresponding to the separation channel 30 higher than at least the drive frequency f1 of the first ultrasonic element 61. In this case, the acoustic radiation force increases for the separation channel 30, which has a channel width larger than that of the inflow channel 20, and the region of the near-field sound field where the density of sound waves is high can be expanded. As a result, even if the fine particles are microfibers, the microfibers can be efficiently captured and flowed into the first outlet flow path 40.

[0061] Summary of this disclosure A method for driving a fluidic device according to a first aspect of the present disclosure includes an inlet flow channel through which a fluid flows in a first direction, a separation flow channel into which the fluid is introduced from the inlet flow channel and which captures particles in the fluid using standing waves, a first outlet flow channel through which the fluid with a high content of the captured particles flows out from the separation flow channel, a second outlet flow channel through which the fluid with a low content of the captured particles flows out from the separation flow channel, a first ultrasonic element disposed in the inlet flow channel and which forms a first standing wave in the inlet flow channel in a second direction perpendicular to the first direction, and a second ultrasonic element disposed in the separation flow channel and which forms a second standing wave in the separation flow channel in the second direction. and a second ultrasonic element that forms two standing waves, the method comprising: a reference setting step of setting a reference position of a node or antinode of the standing wave in the second direction; a first search step of searching for a first frequency of the standing wave at which a node or antinode is located within a predetermined tolerance range from the reference position; a second search step of searching for a second frequency of the second standing wave at which a node or antinode is located within the tolerance range from the reference position; and a drive step of driving the first ultrasonic element at the searched first frequency and driving the second ultrasonic element at the searched second frequency. This allows for control of the behavior of particles immediately before they are trapped at the node or antinode of the standing wave in the separation channel, improving particle trapping efficiency. Furthermore, the flow channel widths of the inlet and separation channels may contain minute errors during the manufacturing process of the fluidic device. In this case, minute errors in the flow channel widths prevent the formation of the appropriate first and second standing waves for trapping particles, reducing the trapping efficiency. In contrast, the method for driving a fluidic device disclosed herein allows for the search for a frequency capable of forming a standing wave for a given flow channel width, even when the flow channel width of the fluidic device contains manufacturing errors, improving particle trapping efficiency.

[0062] In the method for driving a fluidic device of this aspect, it is preferable that in the first search step, a first deviation amount, which is the deviation amount between the position of a node or antinode of the standing wave and the reference position, is calculated, and the first frequency is searched for based on the difference between the first deviation amount and a predetermined first reference deviation amount. This makes it possible to search for a first frequency that can form a first standing wave in which a node or antinode appears at a position close to the set reference position.

[0063] In the method for driving a fluidic device of this aspect, in the second search step, it is preferable to calculate a second deviation amount, which is the deviation between the position of a node or antinode of the second standing wave and the position of a node or antinode of the standing wave formed at the searched first frequency, and to search for the second frequency based on the difference between the second deviation amount and a predetermined second reference deviation amount. This makes it possible to search for a second frequency that can form a second standing wave having a node or antinode close to the position where the particle is trapped in the first standing wave.

[0064] In the method for driving a fluidic device according to this aspect, it is preferable that the second reference deviation amount be set based on the wavelength of the ultrasonic waves that form the standing wave. This allows the formation of a second standing wave that suppresses the diffusion of particles when they flow from the inflow channel into the separation channel.

[0065] In the method for driving a fluidic device of this aspect, if the second deviation amount is greater than the second reference deviation amount in the second search step, it is preferable to increase the order of the second standing wave and search for the second frequency. By using a second standing wave of a higher order, the distance between nodes or antinodes can be reduced, and a second standing wave having a node or antinode close to the node or antinode position that captures the particles of the first standing wave can be searched for.

[0066] In the method for driving a fluidic device of this aspect, the fluidic device further includes a third ultrasonic element disposed in the first outlet flow path and forming a third standing wave in the first outlet flow path toward the second direction, the first outlet flow path is provided at a position opposite the inlet flow path, and a third search step is further performed to search for a third frequency of the third standing wave whose node or antinode is located within the allowable range from the reference position, and in the driving step, the third ultrasonic element is driven at the searched third frequency. This allows the particles captured at the node or antinode of the second standing wave in the separation channel to be captured and flown at the node or antinode of the standing wave in the first outlet channel, improving the particle capture efficiency. Also, even if the channel width of the first outlet channel includes manufacturing errors, it is possible to search for a frequency that can form a standing wave for that channel width, improving the particle capture efficiency.

[0067] In the method for driving a fluidic device of this aspect, in the third search step, it is preferable to calculate a third deviation amount, which is the deviation between the position of a node or antinode of the third standing wave and the position of a node or antinode of the second standing wave formed at the searched second frequency, and to search for the third frequency based on the difference between the third deviation amount and a predetermined third reference deviation amount. This makes it possible to search for a third frequency that can form a third standing wave having a node or antinode close to the position where the particle is trapped in the second standing wave.

[0068] In the method for driving a fluidic device of this aspect, it is preferable that the third reference deviation amount be set based on the wavelength of the ultrasonic waves that form the second standing wave. This allows the third standing wave to be formed so as to suppress the diffusion of the particles when they flow from the separation channel into the first outlet channel.

[0069] a first ultrasonic element disposed in the inlet flow channel and forming a first standing wave in the inlet flow channel toward a second direction perpendicular to the first direction; a second ultrasonic element disposed in the separation flow channel and forming a second standing wave in the separation flow channel toward the second direction; and a control unit that controls driving of the first ultrasonic element and the second ultrasonic element, wherein the control unit sets a reference position of a node or antinode of the standing wave in the second direction, searches for a first frequency of the standing wave at which a node or antinode is located within a predetermined tolerance range from the reference position, searches for a second frequency of the second standing wave at which a node or antinode is located within the tolerance range from the reference position, drives the first ultrasonic element at the searched first frequency, and drives the second ultrasonic element at the searched second frequency. As a result, similar to the first aspect, it is possible to control the behavior of the microparticles immediately before they are trapped at the node or antinode of the standing wave in the separation channel, thereby improving the efficiency of trapping the microparticles. Furthermore, even if the channel width of the fluidic device contains manufacturing errors, it is possible to search for a frequency that can form a standing wave for that channel width, thereby improving the efficiency of trapping the microparticles. [Explanation of symbols]

[0070] 10, 10A, 10B, 10C...fluidic device, 11...flow path member, 20, 20A...inlet flow path, 21, 2...wall surface of inlet flow path, 30, 30A...separation flow path, 31, 32...wall surface of separation flow path, 40, 40A...first outlet flow path, 41, 42...wall surface of first outlet flow path, 43...concentration port, 50, 50A...second outlet flow path, 51, 52...wall surface of second outlet flow path, 53...purification port, 60...ultrasonic transmitting unit, 61, 61A, 61B...first ultrasonic element, 62, 62A, 62B...second ultrasonic element, 63, 63A, 63B...third ultrasonic element, 64...first drive circuit, 65...second drive circuit, 66...third drive circuit, 70...control unit, 71...memory unit, 72...processor, 112...partition unit, 721...reference setting unit, 722...frequency search unit, 723...ultrasonic control unit.

Claims

1. a first outlet flow path through which the fluid captured from the separation flow path flows out; a second outlet flow path through which the fluid captured from the separation flow path flows out; a first ultrasonic element disposed in the inflow flow path, which forms a first standing wave in the inflow flow path in a second direction perpendicular to the first direction; and a second ultrasonic element disposed in the separation flow path, which forms a second standing wave in the separation flow path in the second direction, a reference setting step of setting a reference position of a node or antinode of a standing wave in the second direction; a first search step of searching for a first frequency of the standing wave whose node or antinode is located within a predetermined tolerance range from the reference position; a second search step of searching for a second frequency of the second standing wave whose node or antinode is located within the tolerance range from the reference position; A driving step of driving the first ultrasonic element at the searched first frequency and driving the second ultrasonic element at the searched second frequency; A method for driving a fluidic device.

2. In the first search step, a first deviation amount is calculated, which is a deviation amount between a node or antinode position of the standing wave and the reference position, and the first frequency is searched for based on a difference between the first deviation amount and a predetermined first reference deviation amount. A method for driving a fluidic device according to claim 1 .

3. In the second search step, a second deviation amount is calculated, which is a deviation amount between a position of a node or antinode of the second standing wave and a position of a node or antinode of the standing wave formed at the searched first frequency, and the second frequency is searched based on a difference between the second deviation amount and a predetermined second reference deviation amount. A method for driving a fluidic device according to claim 1 .

4. the second reference deviation amount is set based on the wavelength of the ultrasonic waves forming the standing wave; The method for driving the fluidic device according to claim 3 .

5. In the second search step, if the second deviation amount is greater than the second reference deviation amount, the order of the second standing wave is increased to search for the second frequency. The method for driving the fluidic device according to claim 3 .

6. the fluidic device further includes a third ultrasonic element disposed in the first outlet flow path and forming a third standing wave in the first outlet flow path toward the second direction, the first outlet flow path being provided at a position opposite the inlet flow path; further performing a third search step of searching for a third frequency of the third standing wave, the third frequency having a node or antinode located within the tolerance range from the reference position; In the driving step, the third ultrasonic element is driven at the searched third frequency. A method for driving a fluidic device according to claim 1 .

7. in the third search step, a third deviation amount is calculated, which is a deviation amount between a position of a node or antinode of the third standing wave and a position of a node or antinode of the second standing wave formed at the searched second frequency, and the third frequency is searched for based on a difference between the third deviation amount and a predetermined third reference deviation amount. The method for driving the fluidic device according to claim 6 .

8. the third reference deviation amount is set based on the wavelength of the ultrasonic waves forming the second standing wave. The method for driving the fluidic device according to claim 7 .

9. A fluidic device that separates particles in a fluid using ultrasound, an inlet flow channel through which fluid flows in a first direction; a separation channel into which the fluid flows from the inlet channel; a first outlet flow path for causing the fluid to flow out from the separation flow path; a second outlet flow path for causing the fluid to flow out from the separation flow path; a first ultrasonic element disposed in the inflow channel and configured to generate a standing wave in the inflow channel in a second direction perpendicular to the first direction; a second ultrasonic element disposed in the separation channel to form a second standing wave in the separation channel in the second direction; a control unit that controls the driving of the first ultrasonic element and the second ultrasonic element, The control unit sets a reference position of a node or antinode of a standing wave in the second direction, searches for a first frequency of the standing wave at which a node or antinode is located within a predetermined tolerance range from the reference position, searches for a second frequency of the second standing wave at which a node or antinode is located within the tolerance range from the reference position, drives the first ultrasonic element at the searched first frequency, and drives the second ultrasonic element at the searched second frequency.

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