Fluidic device and method for controlling the fluidic device

Abstract

To provide a fluid device that can stably generate standing wave.SOLUTION: The fluid device 10 includes flow path 20 extending along the X-axis and inside of which fluid S flows, a standing wave generating unit 30 for generating standing wave SW along the Y-axis in fluid S in the flow path 20, a transmitting / receiving unit 40 for transmitting ultrasonic wave to fluid S in the flow path 20 as well as for receiving ultrasonic wave transmitted through fluid S, a flight time measuring unit 55 for measuring the flight time, which is the time from when transmitting / receiving unit 40 transmits ultrasonic wave until when receiving the same, and a driving control unit 582 for controlling driving of the standing wave generating unit 30 based on sonic wave flight time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, fluidic devices that acoustically focus particles in a fluid are known. For example, the fluidic device disclosed in Non-Patent Document 1 includes a flow channel substrate (glass substrate) on which a flow channel is formed, and a piezoelectric element provided on the flow channel substrate. Ultrasonic waves generated by the piezoelectric element are transmitted into the flow channel via the flow channel substrate, generating standing waves in the fluid in the flow channel. The particles in the fluid are trapped within a predetermined range in the flow channel due to the pressure gradient of the fluid formed by the standing wave. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Nobutoshi Ota and six others, "Enhancement in acoustic focusing of micro and nanoparticles by thinning a microfluidic device," Royal Society Open Science, Volume 6, Issue 2, Article No. 181776, December 2019 Summary of the Invention [Problem to be solved by the invention]

[0004] The fluidic device described in Non-Patent Document 1 above focuses microparticles in a fluid using ultrasonic standing waves, but it has been difficult to generate standing waves stably because the conditions for generating the standing waves change due to external disturbances such as temperature fluctuations. [Means for solving the problem]

[0005] A fluidic device of a first aspect according to the present disclosure comprises a flow path extending along a first axis and through which a fluid flows; a standing wave generating unit that generates a standing wave in the fluid within the flow path along a second axis perpendicular to the first axis; a transceiver unit that transmits ultrasonic waves to the fluid within the flow path and receives the ultrasonic waves transmitted by the fluid; a time-of-flight measuring unit that measures the time from when the transceiver unit transmits the ultrasonic waves to when it receives them; and a drive control unit that controls the drive of the standing wave generating unit based on the time-of-flight.

[0006] In the fluid device of the first embodiment, the standing wave generating unit may be a first ultrasonic element arranged in the flow path, the transmitting / receiving unit may be a second ultrasonic element arranged at a different position in the flow path from the first ultrasonic element, the time-of-flight measuring unit may measure the time of flight, which is the time from when the second ultrasonic element transmits the ultrasonic wave to when it receives a reflected wave of the ultrasonic wave, and the drive control unit may control the drive frequency of the first ultrasonic element based on the time of flight.

[0007] In the fluid device of the first embodiment, the standing wave generating unit is a first ultrasonic element arranged in the flow path, and the transmitting / receiving unit includes a second ultrasonic element arranged at a position different from the first ultrasonic element in the flow path and transmitting the ultrasonic wave to the fluid in the flow path, and a third ultrasonic element arranged at a position opposite the second ultrasonic element in the flow path and receiving the ultrasonic wave transmitted from the second ultrasonic element and transmitted through the fluid in the flow path, and the time-of-flight measuring unit measures the time-of-flight, which is the time from when the second ultrasonic element transmits the ultrasonic wave to when the third ultrasonic element receives the ultrasonic wave, and the drive control unit may control the drive frequency of the first ultrasonic element based on the time-of-flight.

[0008] In the first embodiment of the fluid device, the standing wave generating unit and the transmitting / receiving unit are the same ultrasonic element, and the device further includes a switch unit that can switch between a first mode in which the ultrasonic element operates as the standing wave generating unit and a second mode in which the ultrasonic element operates as the transmitting / receiving unit, and the time-of-flight measuring unit measures the time-of-flight, which is the time from when the ultrasonic element in the second mode transmits the ultrasonic wave to when it receives it, and the drive control unit may control the drive frequency of the ultrasonic element in the first mode.

[0009] A second aspect of the present disclosure is a control method for a fluidic device comprising: a flow path extending along a first axis and through which a fluid flows; a standing wave generating unit that generates a standing wave in the fluid within the flow path along a second axis perpendicular to the first axis; and a transceiver unit that transmits ultrasonic waves to the fluid within the flow path and receives the ultrasonic waves transmitted by the fluid, the control method including a measurement step of measuring the time of flight, which is the time from when the transceiver unit transmits the ultrasonic waves to when it receives them, and a control step of controlling the drive of the standing wave generating unit based on the time of flight. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram schematically illustrating a fluidic device according to a first embodiment. [Figure 2] 4 is a flowchart illustrating a control method for the fluidic device of the first embodiment. [Figure 3] FIG. 4 is a diagram schematically illustrating a fluidic device according to a second embodiment. [Figure 4] FIG. 10 is a diagram schematically illustrating a fluidic device according to a third embodiment. [Figure 5] 10 is a flowchart illustrating a control method for a fluidic device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] A fluidic device 10 according to a first embodiment will be described below with reference to FIG. FIG. 1 is a cross-sectional view schematically showing a fluidic device 10 of the first embodiment. The fluidic device 10 includes a flow path 20 that extends along the X-axis, which is a first axis, and through which a fluid S flows, a standing wave generating unit 30 that generates a standing wave SW along the Y-axis, which is a second axis, in the fluid S in the flow path 20, a transmitting / receiving unit 40 that transmits ultrasonic waves to the fluid S in the flow path 20 and receives ultrasonic waves transmitted by the fluid S, and a control unit 50 that controls the driving of the standing wave generating unit 30. The X-axis and Y-axis are axes that are orthogonal to each other, and the axis that is orthogonal to each of the X-axis and Y-axis is referred to as the Z-axis.

[0012] In this fluidic device 10, a standing wave SW of an arbitrary mode order is formed along the Y-axis in a partial region in the X-axis direction within the flow channel 20. As particles M dispersed in the fluid S flow through the flow channel 20, they are affected by the pressure gradient formed by the standing wave SW and converge to a predetermined range centered on a node of the standing wave SW. The fluid S is not particularly limited, but may be, for example, water or blood. The particles M may be, for example, microfibers or cells. In such a fluid device 10, for example, the flow path 20 can be provided with a concentration flow path that selectively circulates the fluid S containing the converged particles M, and a discharge flow path that selectively circulates other fluids S, thereby concentrating the particles M in the fluid S. 1 schematically illustrates the state of the particles M converged within the flow path 20. In addition, as an example, FIG. 1 also schematically illustrates a standing wave SW of a first mode generated within the flow path 20, but the mode order of the standing wave SW is not particularly limited.

[0013] The flow channel 20 has a first wall surface 21 and a second wall surface 22 that face each other in the Y-axis direction. The flow channel width L between the first wall surface 21 and the second wall surface 22 is a known value. The specific configuration of the flow channel 20 is not particularly limited, but may be formed, for example, by a base substrate in which a groove is formed and a lid substrate that covers the groove, and each substrate may be a glass substrate, a silicon substrate, or the like.

[0014] Although not shown, the flow path 20 is provided with an inlet for injecting the fluid S into the flow path 20 and one or more outlets for discharging the fluid S from the flow path 20. When the flow path 20 is provided with the concentration flow path and the discharge flow path as described above, an outlet is provided for each flow path.

[0015] The standing wave generating unit 30 is an ultrasonic element (first ultrasonic element) provided in the flow path 20, and generates a standing wave SW in the fluid S by transmitting ultrasonic waves of a predetermined frequency to the fluid S in the flow path 20. In particular, in this embodiment, the ultrasonic wave transmitting surface 30S of the standing wave generating unit 30 forms part of the first wall surface 21 of the flow path 20, and generates a standing wave SW along the Y-axis direction.

[0016] The transmitter / receiver 40 is an ultrasonic element (second ultrasonic element) arranged in a position different from the standing wave generating unit 30 in the flow channel 20, and transmits ultrasonic waves of an arbitrary frequency to the fluid S in the flow channel 20. The transmitter / receiver 40 also receives ultrasonic waves transmitted through the fluid S, and outputs a reception signal corresponding to the ultrasonic waves. In particular, in this embodiment, the ultrasonic wave transmitting / receiving surface 40S of the transmitter / receiver 40 forms part of the first wall surface 21 of the flow channel 20, and receives ultrasonic waves transmitted from the ultrasonic wave transmitting / receiving surface 40S and reflected by the second wall surface 22 of the flow channel 20.

[0017] The specific configuration of each ultrasonic element constituting the standing wave generating unit 30 or the transmitting / receiving unit 40 is not particularly limited. For example, the ultrasonic element may have a configuration that vibrates a piezoelectric actuator, a configuration that vibrates a diaphragm on which a piezoelectric thin film is formed, or a configuration that vibrates a diaphragm included in an electrostatic actuator. Such ultrasonic elements generate vibrations when a voltage is applied as a drive signal, and transmit ultrasonic waves. Furthermore, the relative position of the transmitter / receiver 40 with respect to the standing wave generating unit 30 is not particularly limited, but it is preferable that the transmitter / receiver 40 is located far enough from the standing wave generating unit 30 that it does not affect the generation of the standing wave SW, and is located in a position where the temperature of the fluid S is approximately the same between the area where the transmitter / receiver 40 transmits ultrasound and the area where the standing wave SW is generated.

[0018] The control unit 50 includes a continuous wave generating circuit 51 connected to the standing wave generating unit 30, a burst wave generating circuit 52 and a receiving circuit 53 connected to the transmitting / receiving unit 40, a TOF measurement circuit 54 connected to the receiving circuit 53, and a CPU (Central Processing Unit) 56 that controls each circuit.

[0019] The continuous wave generating circuit 51 generates a drive signal of a predetermined frequency under the control of the CPU 56, and continuously outputs the drive signal to the standing wave generating unit 30. The frequency of the drive signal generated by the continuous wave generating circuit 51 (hereinafter referred to as drive frequency Fd) is set so as to generate a standing wave in the fluid S.

[0020] The burst wave generating circuit 52 generates a drive signal of an arbitrary frequency in response to a measurement request from the CPU 56, and outputs the drive signal to the transmitting / receiving unit 40 for a predetermined period of time. The receiving circuit 53 is configured to include, for example, an amplifier circuit and a detection circuit, and performs signal processing on the received signal output when ultrasound is received by the transceiver 40, and outputs the processed received signal to the TOF measurement circuit 54. The TOF measurement circuit 54 measures the time of flight (TOF value), which is the time from when the transceiver 40 transmits ultrasonic waves to when it receives them, based on a timing signal input simultaneously with a request from the CPU 56 to the burst wave generating circuit 52 and a receiving signal input from the receiving circuit 53. In this embodiment, the burst wave generating circuit 52, the receiving circuit 53, and the TOF measuring circuit 54 constitute a time-of-flight measuring unit 55 for measuring the TOF value.

[0021] The CPU 56 includes a memory 57 in which various programs and various data are stored, and a processor 58 that executes the programs stored in the memory 57 . The memory 57 stores the current value of the drive frequency Fd of the standing wave generating section 30 and the like. By executing a program stored in memory 57, processor 58 functions as a measurement control unit 581 that outputs a measurement request to burst wave generating circuit 52, and a drive control unit 582 that controls the drive frequency Fd of standing wave generating unit 30 based on the TOF value measured by TOF measurement circuit 54.

[0022] Next, the control of the fluidic device 10 of this embodiment will be described with reference to the flowchart of Fig. 2. Note that the following describes the control while standing waves are occurring in the fluidic device 10.

[0023] First, when a predetermined measurement timing arrives (Step S1; Yes), the measurement control unit 581 outputs a measurement request to the burst wave generation circuit 52, and the burst wave generation circuit 52 outputs a drive signal for forming a burst wave for a predetermined time (Step S2). As a result, the transceiver 40 transmits ultrasonic waves for a predetermined time in response to the drive signal input from the burst wave generation circuit 52. The ultrasonic waves are transmitted to the fluid S, reflected by the second wall surface 22 of the flow path 20, and then incident on the transceiver 40. The transceiver 40 outputs a reception signal corresponding to the incident ultrasonic waves, and the TOF measurement circuit 54 measures a TOF value, which is the time from when the transceiver 40 transmits the ultrasonic waves to when it receives them, based on the reception signal.

[0024] Next, the drive control unit 582 determines the optimum drive frequency Fs for generating a standing wave in the fluid S in the flow channel 20 based on the TOF value input from the TOF measurement circuit 54 (step S3). Here, the condition for generating a standing wave in the fluid S in the flow path 20 is expressed by the following formula (1): In the formula, Fs is the optimal drive frequency, m is the order of the standing wave SW, c is the speed of sound in the fluid S, and L is the flow path width of the flow path 20.

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[0025] Thereafter, the drive control section 582 refers to the memory 57 and determines whether or not the optimum drive frequency Fs calculated in step S3 above matches the current drive frequency Fd in the standing wave generating section 30 (step S4). Note that the drive control section 582 may determine that they "match" when the absolute value of the difference between the current drive frequency Fd and the optimum drive frequency Fs is equal to or less than a predetermined threshold value.

[0026] If it is determined that the optimum drive frequency Fs matches the current drive frequency Fd (step S4; YES), the processing in the control unit 50 returns to step S1. On the other hand, if it is determined that the optimum drive frequency Fs does not match the current drive frequency Fd of the standing wave generating section 30 (step S4; NO), the drive control section 582 adjusts the drive frequency Fd to match the optimum drive frequency Fs (step S5; control step). After that, the processing in the control section 50 returns to step S1. It is preferable that the control unit 50 repeatedly performs the above-described flow chart at predetermined intervals to trigger measurement.

[0027] [Effects of the first embodiment] As described above, the fluidic device 10 of this embodiment comprises a flow path 20 extending along the X-axis and through which a fluid S flows, a standing wave generating unit 30 that generates a standing wave SW along the Y-axis in the fluid S within the flow path 20, a transceiver unit 40 that transmits ultrasonic waves to the fluid S within the flow path 20 and receives the ultrasonic waves transmitted by the fluid S, a time-of-flight measuring unit 55 that measures the time from when the transceiver unit 40 transmits the ultrasonic waves to when it receives them, and a drive control unit 582 that controls the drive of the standing wave generating unit 30 based on the TOF value.

[0028] This fluidic device 10 generates a standing wave SW in a fluid S in a flow path 20 by a standing wave generating unit 30. In this fluidic device 10, when the temperature of the fluid S changes, the speed of sound in the fluid S changes, and therefore the driving conditions of the standing wave generating unit 30 for generating the standing wave SW also change. Therefore, in this embodiment, the time-of-flight measurement unit 55 measures a TOF value related to the speed of sound in the fluid S, and the drive control unit 582 controls the drive of the standing wave generating unit 30 based on the TOF value. This makes it possible to feedback-control the drive of the standing wave generating unit 30 in response to temperature changes in the fluid S. As a result, it is possible to stably generate the standing wave SW.

[0029] In order to perform control that follows the temperature change of the fluid S, it is possible to consider a method of directly measuring the temperature of the fluid S by providing a temperature sensor in the flow path 20, but this would impose a heavy load on the calculation process of determining the drive conditions of the standing wave generating unit 30 based on the temperature of the fluid S. On the other hand, in this embodiment, by using the TOF value in the fluid S instead of the temperature of the fluid S, it is possible to easily determine the optimal drive frequency Fs, which is the drive condition of the standing wave generating unit 30, and the load on the calculation process can be reduced.

[0030] In this embodiment, the standing wave generating unit 30 is a first ultrasonic element arranged in the flow path 20, the transmitter / receiver unit 40 is a second ultrasonic element arranged in a position different from the standing wave generating unit 30 in the flow path 20, the time-of-flight measuring unit 55 measures the TOF value, which is the time from when the standing wave generating unit 30 transmits an ultrasonic wave to when it receives a reflected wave of the ultrasonic wave, and the drive control unit 582 controls the drive frequency of the standing wave generating unit 30 based on the TOF value. In this configuration, the transmission / reception unit 40 can be simply configured by utilizing the reflected waves within the flow path 20.

[0031] Furthermore, in this embodiment, by using water as the fluid S, it is possible to provide a fluidic device 10 that can appropriately separate fine particles M contained in water, thereby broadening the range of applications. For example, by flowing domestic wastewater discharged from a washing machine or a kitchen into the fluidic device 10, it is possible to separate the fine particles contained in the domestic wastewater. In this case, it is possible to separate fine plastic fibers contained in the washing water and abrasive powder from detergent contained in kitchen wastewater, thereby making it possible to reduce environmental damage caused by substances such as plastic waste. However, the fluid S is not limited to water. For example, by using blood as the fluid S, it is possible to provide a fluidic device 10 capable of separating cellular components contained in the blood. If the cellular components are cancer cells in the blood, the cancer cells contained in the blood can be separated and removed, and it is also possible to suppress the metastasis of cancer.

[0032] [Second embodiment] Next, a fluidic device 10A according to a second embodiment will be described with reference to FIG. FIG. 3 is a diagram schematically illustrating a fluidic device 10A according to the second embodiment. The fluidic device 10A has almost the same configuration as the fluidic device 10 of the first embodiment, except for the configuration of the transceiver 40A. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted or simplified.

[0033] In the second embodiment, the transmitter / receiver 40A includes a second ultrasonic element 41 and a third ultrasonic element 42 that are arranged in a position different from the standing wave generating unit 30 (i.e., the first ultrasonic element) in the flow path 20. The second ultrasonic element 41 transmits ultrasonic waves of an arbitrary frequency to the fluid S in the flow path 20. The third ultrasonic element 42 is arranged opposite the second ultrasonic element 41, and receives ultrasonic waves transmitted from the second ultrasonic element 41 and propagated through the fluid S, thereby outputting a reception signal corresponding to the ultrasonic waves. In particular, in this embodiment, the ultrasonic transmitting surface 41S of the second ultrasonic element 41 forms part of the first wall surface 21 of the flow path 20, and the ultrasonic receiving surface 42S of the third ultrasonic element 42 forms part of the second wall surface 22 of the flow path 20.

[0034] The burst wave generating circuit 52 generates a drive signal of an arbitrary frequency in response to a measurement request from the CPU 56, and outputs the drive signal to the second ultrasonic element 41 of the transmitting / receiving unit 40A for a predetermined period of time. The receiving circuit 53 is configured to include, for example, an amplifier circuit and a detection circuit, and performs signal processing on the received signal output when an ultrasonic wave is received by the third ultrasonic element 42 of the transceiver unit 40A, and outputs the processed received signal to the TOF measurement circuit 54. The TOF measurement circuit 54 measures the time of flight (TOF value), which is the time from when the second ultrasonic element 41 transmits an ultrasonic wave until when the third ultrasonic element 42 receives the ultrasonic wave.

[0035] In the fluidic device 10A according to the second embodiment, control is performed according to the flowchart of FIG. 2, similarly to the first embodiment. Here, the condition for generating a standing wave in the fluid S in the flow path 20 is expressed by the following formula (1), as in the first embodiment. In the formula, Fs is the optimum drive frequency, m is the order of the standing wave SW, c is the sound speed in the fluid S, and L is the flow path width of the flow path 20.

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[0036] According to the second embodiment, similar to the first embodiment described above, even when the temperature of the fluid S changes, the standing wave SW can be generated stably. Furthermore, in the second embodiment, the transmitting / receiving unit 40A is divided into the second ultrasonic element 41, which is the ultrasonic wave transmitting side, and the third ultrasonic element 42, which is the ultrasonic wave receiving side, so that reception noise due to reverberation during ultrasonic wave transmission is unlikely to occur even when the flow path width L is small. Therefore, compared to the first embodiment, even when the flow path width L is small, the drive of the standing wave generating unit 30 can be feedback-controlled with high precision.

[0037] [Third embodiment] Next, a fluidic device 10B according to a third embodiment will be described with reference to FIG. FIG. 4 is a diagram schematically illustrating a fluidic device 10B according to the third embodiment. In the fluidic device 10B, the standing wave generating unit 30 and the transmitting / receiving unit 40 of the first embodiment are configured using the same ultrasonic element 60. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted or simplified.

[0038] In the third embodiment, the ultrasonic element 60 is provided in the flow path 20 and can be switched between a first mode in which it operates as a standing wave generating unit and a second driving mode in which it operates as a transmitting and receiving unit. The first mode ultrasonic element 60 transmits ultrasonic waves of a predetermined frequency to the fluid S in the flow channel 20, thereby generating standing waves SW in the fluid S. The second mode ultrasonic element 60 transmits ultrasonic waves of an arbitrary frequency to the fluid S in the flow path 20, and receives ultrasonic waves transmitted through the fluid S, thereby outputting a reception signal corresponding to the ultrasonic waves. In particular, in this embodiment, the ultrasonic transmission / reception surface 60S of the ultrasonic element 60 is arranged to form part of the first wall surface 21 of the flow path 20, and the ultrasonic element 60 receives ultrasonic waves transmitted from the ultrasonic transmission / reception surface 60S and reflected by the second wall surface 22 of the flow path 20.

[0039] The control unit 50B further includes a switch unit 59 that switches between the first mode and the second mode of the ultrasonic element 60. One end of this switch unit 59 is connected to the ultrasonic element 60, and the other end can be switched between the continuous wave generating circuit 51 and the burst wave generating circuit 52. In the control unit 50B, the processor 58 also functions as a mode switching unit 583 that controls the connection of the switch unit 59.

[0040] Next, the control of the fluidic device 10B of the third embodiment will be described with reference to the flowchart of Fig. 5. Note that the same steps as those in the first embodiment are denoted by the same reference numerals, and the description may be simplified.

[0041] First, in the initial stage, the switch unit 59 is connected to the continuous wave generating circuit 51, and the first mode ultrasonic element 60 generates a standing wave SW. When a predetermined measurement timing arrives (Step S1; Yes), the mode switching unit 583 outputs a switching signal to the switch unit 59, and the measurement control unit 581 outputs a measurement request to the burst wave generating circuit 52. Then, the connection of the switch unit 59 switches from the continuous wave generating circuit 51 to the burst wave generating circuit 52 (Step S11), and the burst wave generating circuit 52 outputs a drive signal for forming a burst wave for a predetermined time (Step S2). This causes the ultrasonic element 60 to switch from the first mode to the second mode and transmit ultrasonic waves for a predetermined time in response to the drive signal input from the burst wave generating circuit 52. The ultrasonic waves are transmitted to the fluid S, reflected by the second wall surface 22 of the flow path 20, and then incident on the ultrasonic element 60. The ultrasonic element 60 outputs a reception signal corresponding to the incident ultrasonic waves, and the TOF measurement circuit 54 measures a TOF value, which is the time from when the ultrasonic element 60 transmits ultrasonic waves to when the ultrasonic element 60 receives the ultrasonic waves, based on the reception signal.

[0042] Next, the drive control unit 582 determines the optimum drive frequency Fs for generating a standing wave in the fluid S in the flow channel 20 based on the TOF value input from the TOF measurement circuit 54 (step S3). Thereafter, the drive control unit 582 refers to the memory 57 and determines whether or not the optimum drive frequency Fs calculated in the above-mentioned step S3 matches the drive frequency Fd of the ultrasonic element 60 in the first mode (step S4). Note that the drive control unit 582 may determine that they "match" when the absolute value of the difference between the drive frequency Fd and the optimum drive frequency Fs is equal to or less than a predetermined threshold value.

[0043] If it is determined that the optimum drive frequency Fs matches the drive frequency Fd (step S4; YES), the process in the control unit 50 proceeds to step S12, which will be described later. On the other hand, if it is determined that the optimum drive frequency Fs does not match the drive frequency Fd (step S4; NO), the drive control unit 582 adjusts the drive frequency Fd to match the optimum drive frequency Fs (step S5).

[0044] Then, when the mode switching unit 583 outputs a switching signal to the switch unit 59, the connection of the switch unit 59 switches from the burst wave generating circuit 52 to the continuous wave generating circuit 51 (step S12). As a result, the ultrasonic element 60 switches from the second mode to the first mode, and the generation of the standing wave SW is resumed. Thereafter, the process returns to step S1 in the control unit 50. It is preferable that the control unit 50 repeats the measurement timing at predetermined intervals and repeats the above-described flowchart.

[0045] According to the third embodiment, similar to the first embodiment described above, even when the temperature of the fluid S changes, the standing wave SW can be generated stably. Furthermore, in the third embodiment, one ultrasonic element 60 serves as both a standing wave generating section and a transmitting / receiving section, which allows the configuration of the fluidic device 10B to be simplified.

[0046] [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.

[0047] In the first embodiment, the standing wave generating unit 30 and the transmitting / receiving unit 40 each form a flow path wall surface of the flow path 20, but this is not limiting. For example, a wall member of the flow path 20 may be disposed between the standing wave generating unit 30 and the fluid S, or a wall member of the flow path 20 may be disposed between the transmitting / receiving unit 40 and the fluid S. When a wall member of the flow path 20 is disposed between the transmitting / receiving unit 40 and the fluid S, it is preferable to determine the optimal drive frequency Fs by performing a calculation process that takes into account the propagation time of the ultrasonic waves through the wall member. Such modifications also apply to the second and third embodiments.

[0048] Furthermore, in the first embodiment, the transmitter / receiver unit 40 is arranged so that the ultrasound transmitting / receiving surface 40S faces the Y-axis direction, but this is not limited thereto and the transmitter / receiver unit 40 may be arranged so that the ultrasound transmitting / receiving surface 40S faces in a direction intersecting the Y-axis direction, for example, the Z-axis direction. In such a modified example, it is preferable to determine in advance the transmission / reception distance x that the ultrasound travels through the fluid S in order to measure the TOF value. As a result, in the above-mentioned step S3, the optimal drive frequency Fs can be determined by substituting the TOF value into the following equation (6). This modified example also applies to the second embodiment.

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[0049] Furthermore, in each of the above embodiments, the method of controlling the drive of the standing wave generating unit based on the TOF value is not limited to the method of calculating the optimal drive frequency Fs, and other calculations may be performed, such as determining the frequency change range based on the TOF value change range.

[0050] Summary of this disclosure A fluidic device of a first aspect according to the present disclosure comprises a flow path extending along a first axis and through which a fluid flows; a standing wave generating unit that generates a standing wave in the fluid within the flow path along a second axis perpendicular to the first axis; a transceiver unit that transmits ultrasonic waves to the fluid within the flow path and receives the ultrasonic waves transmitted by the fluid; a time-of-flight measuring unit that measures the time from when the transceiver unit transmits the ultrasonic waves to when it receives them; and a drive control unit that controls the drive of the standing wave generating unit based on the time-of-flight. This allows feedback control of the driving of the standing wave generating unit in response to changes in the temperature of the fluid, thereby enabling stable generation of standing waves even when the temperature of the fluid changes.

[0051] In the fluid device of the first embodiment, the standing wave generating unit may be a first ultrasonic element arranged in the flow path, the transmitting / receiving unit may be a second ultrasonic element arranged at a different position in the flow path from the first ultrasonic element, the time-of-flight measuring unit may measure the time of flight, which is the time from when the second ultrasonic element transmits the ultrasonic wave to when it receives a reflected wave of the ultrasonic wave, and the drive control unit may control the drive frequency of the first ultrasonic element based on the time of flight. In this configuration, the transmission and reception section can be simply configured by utilizing the reflected waves within the flow path.

[0052] In the fluid device of the first embodiment, the standing wave generating unit is a first ultrasonic element arranged in the flow path, and the transmitting / receiving unit includes a second ultrasonic element arranged at a position different from the first ultrasonic element in the flow path and transmitting the ultrasonic wave to the fluid in the flow path, and a third ultrasonic element arranged at a position opposite the second ultrasonic element in the flow path and receiving the ultrasonic wave transmitted from the second ultrasonic element and transmitted through the fluid in the flow path, and the time-of-flight measuring unit measures the time-of-flight, which is the time from when the second ultrasonic element transmits the ultrasonic wave to when the third ultrasonic element receives the ultrasonic wave, and the drive control unit may control the drive frequency of the first ultrasonic element based on the time-of-flight. In such a configuration, even if the flow path width is small, the driving of the standing wave generating section can be feedback controlled with high precision.

[0053] In the first embodiment of the fluid device, the standing wave generating unit and the transmitting / receiving unit are the same ultrasonic element, and the device further includes a switch unit that can switch between a first mode in which the ultrasonic element operates as the standing wave generating unit and a second mode in which the ultrasonic element operates as the transmitting / receiving unit, the time-of-flight measuring unit measures the time-of-flight, which is the time from when the ultrasonic element in the second mode transmits the ultrasonic wave to when it receives it, and the drive control unit controls the drive frequency of the ultrasonic element in the first mode. In such a configuration, one ultrasonic element serves as both a standing wave generating section and a transmitting / receiving section, and therefore the configuration of the ultrasonic device can be simplified.

[0054] A second aspect of the present disclosure is a control method for a fluidic device comprising: a flow path extending along a first axis and through which a fluid flows; a standing wave generating unit that generates a standing wave in the fluid within the flow path along a second axis perpendicular to the first axis; and a transceiver unit that transmits ultrasonic waves to the fluid within the flow path and receives the ultrasonic waves transmitted by the fluid, the control method including a measurement step of measuring the time of flight, which is the time from when the transceiver unit transmits the ultrasonic waves to when it receives them, and a control step of controlling the drive of the standing wave generating unit based on the time of flight. As a result, similar to the first aspect of the present disclosure, standing waves can be generated stably even when the temperature of the fluid changes. [Explanation of symbols]

[0055] 10, 10A, 10B...fluid device, 20...flow path, 21...first wall surface, 22...second wall surface, 30...standing wave generating section, 30S...ultrasonic transmitting surface, 40, 40A...transmitting and receiving section, 40S...ultrasonic transmitting and receiving surface, 41...second ultrasonic element, 41S...ultrasonic transmitting surface, 42...third ultrasonic element, 42S...ultrasonic receiving surface, 50, 50B...control section, 51...continuous wave generating circuit, 52...burst wave generating circuit, 53...receiving circuit, 54...TOF measurement circuit, 55...time of flight measuring section, 56...CPU, 57...memory, 58...processor, 581...measurement control section, 582...drive control section, 583...mode switching section, 59...switch section, 60...ultrasonic element, 60S...ultrasonic transmitting and receiving surface, L...flow path width, M...microparticle, S...fluid, SW...standing wave.

Claims

1. a flow channel extending along a first axis and through which a fluid flows; A standing wave is generated in the fluid in the flow path along a second axis perpendicular to the first axis. a wave generating unit; An ultrasonic wave is transmitted to the fluid in the flow path, and the ultrasonic wave transmitted to the fluid is received. a transceiver unit for receiving the signal; The transmitting and receiving unit measures a time of flight, which is the time from when the transmitting and receiving unit transmits the ultrasonic wave until when the receiving unit receives the ultrasonic wave. a time-of-flight measurement unit; a drive control unit that controls driving of the standing wave generating unit based on the time of flight, Fluidic devices.

2. the standing wave generating unit is a first ultrasonic element disposed in the flow path, The transmitting and receiving unit includes a second ultrasonic element disposed at a position different from that of the first ultrasonic element in the flow channel. an ultrasonic element, The time-of-flight measurement unit measures the time of flight of the ultrasonic wave after the second ultrasonic element transmits the ultrasonic wave. Measure the time of flight, which is the time it takes to receive the reflected wave; The drive control unit controls a drive frequency of the first ultrasonic element based on the time of flight. The fluidic device according to claim 1 .

3. the standing wave generating unit is a first ultrasonic element disposed in the flow path, The transmitting / receiving unit The first ultrasonic element is disposed at a different position from the first ultrasonic element in the flow path, a second ultrasonic element that transmits the ultrasonic waves into the fluid; a second ultrasonic element disposed in the flow path and facing the second ultrasonic element; a third ultrasonic element for receiving the ultrasonic waves transmitted from the third ultrasonic element and propagating through the fluid in the flow path; and, The time-of-flight measurement unit measures the time from when the second ultrasonic element transmits the ultrasonic wave to when the third ultrasonic element transmits the ultrasonic wave. measuring the time of flight, which is the time it takes for the wave element to receive the ultrasonic wave; The drive control unit controls a drive frequency of the first ultrasonic element based on the time of flight. The fluidic device according to claim 1 .

4. the standing wave generating unit and the transmitting / receiving unit are the same ultrasonic element, a first mode in which the ultrasonic element operates as the standing wave generating unit, and a second mode in which the ultrasonic element operates as the front a switch unit that can switch between a first mode and a second mode in which the transmitter / receiver operates; The time-of-flight measurement unit measures the time of flight from the time when the ultrasonic element in the second mode transmits the ultrasonic wave to the time when the ultrasonic element in the second mode transmits the ultrasonic wave. measuring the time of flight, which is the time it takes to receive the signal; The drive control unit controls the drive frequency of the ultrasonic element in the first mode based on the time of flight. The fluidic device according to claim 1 , wherein the wave number is controlled.

5. a flow path extending along a first axis and having a fluid flowing therethrough; a standing wave generating section for generating a standing wave along a second axis perpendicular to the first axis; a transceiver that transmits ultrasound waves to the body and receives the ultrasound waves transmitted by the fluid; A method for controlling a fluidic device comprising: The transmitting and receiving unit measures a time of flight, which is the time from when the transmitting and receiving unit transmits the ultrasonic wave until when the receiving unit receives the ultrasonic wave. a measurement step; a control step of controlling driving of the standing wave generating unit based on the time of flight, A method for controlling a fluidic device.

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