Fluid apparatus and method of controlling fluid apparatus

Abstract

The present application provides a fluid device and a control method of the fluid device, which can stably generate a standing wave. The fluid device includes: a flow path extending along a first axis, in which a fluid flows; an ultrasonic wave transmitting unit disposed in the flow path, which transmits an ultrasonic wave into the flow path along a second axis orthogonal to the first axis by input of a drive signal; and a control unit that controls the ultrasonic wave transmitting unit, which changes a drive frequency of the drive signal within a predetermined range to measure an impedance of the ultrasonic wave transmitting unit when the ultrasonic wave transmitting unit is driven, and determines a drive frequency at which the impedance is maximum and sets as a first drive frequency, and inputs the drive signal of the first drive frequency to the ultrasonic wave transmitting unit.

Description

Technical Field

[0001] This invention relates to fluid equipment and a method for controlling fluid equipment. Background Technology

[0002] Previously, fluid devices for focusing sound from microparticles in a fluid were known. For example, the fluid device disclosed in Non-Patent Document 1 includes a flow path substrate (glass substrate) with flow paths formed therein and a piezoelectric element disposed on the flow path substrate. Ultrasonic waves generated by the piezoelectric element are transmitted into the flow path via the flow path substrate, causing the fluid in the flow path to generate standing waves. By utilizing the pressure gradient of the fluid formed by the standing waves, microparticles in the fluid are captured within a predetermined range in the flow path.

[0003] Non-patent document 1: Nobutoshi Ota and 6 others, "Enhancement in acoustic focusing of micro and nanoparticles by thinning a microfluidic" device)", December 2019, Royal Society Open Science, Volume 6, No. 2, Note No. 181776 Summary of the Invention

[0004] The fluid device described in Non-Patent Document 1 above is a device that uses standing waves generated by ultrasound to converge microparticles in a fluid. However, since the conditions for generating standing waves vary due to external disturbances such as temperature changes, it is difficult to generate standing waves stably.

[0005] The fluid device according to a first aspect of this disclosure includes: a flow path extending along a first axis, through which fluid flows; an ultrasonic transmitter disposed in the flow path, transmitting ultrasonic waves along a second axis orthogonal to the first axis within the flow path via an input of a drive signal; and a control unit controlling the ultrasonic transmitter, wherein the control unit causes the drive frequency of the drive signal to vary within a predetermined range to measure the impedance of the ultrasonic transmitter when it is driven, determines the drive frequency at which the impedance is at its maximum and sets it as a first drive frequency, and inputs the drive signal at the first drive frequency to the ultrasonic transmitter.

[0006] The second method for controlling a fluid device is used to capture microparticles in a fluid flowing inside a flow path extending along a first axis. The fluid device includes an ultrasonic transmitter disposed in the flow path. The ultrasonic transmitter transmits ultrasonic waves within the flow path along a second axis orthogonal to the first axis via an input drive signal. In the control method of the fluid device, the drive frequency of the drive signal is varied within a predetermined range to measure the impedance of the ultrasonic transmitter when it is driven. The drive frequency at which the impedance is at its maximum is determined and set as a first drive frequency. The drive signal at the first drive frequency is input to the ultrasonic transmitter. Attached Figure Description

[0007] Figure 1 A diagram illustrating the fluid apparatus of the first embodiment is shown.

[0008] Figure 2 A graph showing the change in impedance of the second ultrasonic element when the driving frequency of the second driving signal is changed in the first embodiment.

[0009] Figure 3 A flowchart illustrating the control method of the fluid device according to the first embodiment.

[0010] Figure 4 A graph showing the relationship between the driving frequency and the impedance of the second ultrasonic element when the temperature of the fluid changes in the first embodiment.

[0011] Figure 5 A diagram schematically illustrates the fluid apparatus of the second embodiment.

[0012] Figure 6 A flowchart illustrating the control method of the fluid device according to the second embodiment.

[0013] Explanation of reference numerals in the attached figures

[0014] 10, 10A: Fluid equipment; 20: Flow path; 20A: First position; 20B: Second position; 21: First wall surface; 22: Second wall surface; 30: First ultrasonic element; 30S: Ultrasonic transmitting surface; 40: Second ultrasonic element; 40S: Ultrasonic transmitting surface; 50, 50A: Control unit; 51: Continuous wave generation circuit; 52: Impedance measurement circuit; 53: Memory; 54: Processor; 55: Switching unit; 60: Third ultrasonic element; 60S: Ultrasonic transmitting surface; 541: Measurement control unit; 542: Drive control unit; 543: Mode switching unit; L: Flow path width; M: Microparticle; SW: Standing wave. Detailed Implementation

[0015] First Implementation Method

[0016] The fluid device of the first embodiment will now be described.

[0017] Composition of fluid equipment

[0018] Figure 1 A cross-sectional view of the fluid device 10 of the first embodiment is shown schematically.

[0019] The fluid device 10 includes: a flow path 20 extending along an X-axis (a first axis) for circulating fluid S within the flow path 20; a first ultrasonic element 30 generating a standing wave SW along a Y-axis (a second axis) within the fluid S in the flow path 20; a second ultrasonic element 40 transmitting ultrasonic waves to and receiving ultrasonic waves transmitted through the fluid S in the flow path 20; and a control unit 50 controlling the driving of the first ultrasonic element 30. It should be noted that the X-axis and Y-axis are mutually orthogonal axes, and the axis orthogonal to both the X-axis and Y-axis is designated as the Z-axis.

[0020] In this fluid device 10, a standing wave SW of arbitrary mode order is formed along the Y-axis in a portion of the X-axis region within the flow path 20. Microparticles M dispersed in the fluid S, as they flow through the flow path 20, are influenced by the pressure gradient formed by the standing wave SW and converge towards a predetermined range centered on the nodes of the standing wave SW. The fluid S is not particularly limited and can be, for example, water or blood. The microparticles M can also be, for example, tiny fibers or cells.

[0021] In such a fluid device 10, for example, by providing a concentration flow path for selectively flowing a fluid S containing converged microparticles M and a discharge flow path for selectively flowing other fluids S through the flow path 20, it is possible to concentrate the microparticles M in the fluid S.

[0022] It should be noted that, in Figure 1 The diagram schematically illustrates the appearance of a microparticle M converging within flow path 20. Additionally, in... Figure 1 The diagram schematically illustrates a single-mode standing wave SW generated within flow path 20 as an example, but there is no particular limitation on the number of modes of the standing wave SW.

[0023] The flow path 20 has a first wall 21 and a second wall 22 that are opposite to each other in the Y-axis direction. The flow path width L between these first wall 21 and second wall 22 is a known value. The specific configuration of the flow path 20 is not particularly limited. For example, it can be formed by a base substrate forming a groove and a cover substrate covering the groove. As each substrate, a glass substrate, silicon substrate, etc. can be used.

[0024] Furthermore, in this embodiment, the distance between the first wall 21 and the second wall 22 of the flow path 20, that is, the width along the Y-axis (second axis), is made the same. It should be noted that at least the width along the Y-axis at the first position 20A where the first ultrasonic element 30 is disposed, as described later, is the same as the width along the Y-axis at the second position 20B where the second ultrasonic element 40 is disposed. For example, the width along the Y-axis can be wider or narrower between the first position 20A and the second position 20B.

[0025] Furthermore, in Figure 1 In the example shown, the first position 20A is located downstream (+X side) of the second position 20B, but it can also be located upstream of the second position 20B.

[0026] It should be noted that, although the diagram is omitted, the flow path 20 is provided with an inlet for injecting fluid S into the flow path 20 and one or more outlets for discharging 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.

[0027] The first ultrasonic element 30 constitutes the ultrasonic transmitting section of this disclosure. This first ultrasonic element 30 is positioned at a first location 20A in the flow path 20, facing into the flow path 20, and generates a standing wave SW along the Y-axis in the fluid S by transmitting ultrasonic waves of a predetermined frequency to the fluid S. In this embodiment, the ultrasonic transmitting surface 30S of the first ultrasonic element 30 forms part of the first wall surface 21 of the flow path 20, thereby generating the standing wave SW along the Y-axis direction.

[0028] The second ultrasonic element 40, together with the first ultrasonic element 30, constitutes the ultrasonic transmitting unit of this disclosure. The second ultrasonic element 40 is disposed at a second position 20B in the flow path 20, different from the first position 20A where the first ultrasonic element 30 is disposed. The second ultrasonic element 40 transmits ultrasonic waves of any frequency to the fluid S within the flow path 20. In this embodiment, the ultrasonic transmitting surface 40S of the second ultrasonic element 40 forms part of the first wall surface 21 of the flow path 20.

[0029] It should be noted that the specific configuration of each ultrasonic element constituting the first ultrasonic element 30 or the second ultrasonic element 40 is not particularly limited. For example, the ultrasonic element may have a configuration that vibrates a piezoelectric actuator, a configuration that vibrates a vibrating plate on which a piezoelectric thin film is formed, or a configuration that vibrates a vibrating plate included in an electrostatic actuator. Such an ultrasonic element vibrates and transmits ultrasonic waves by being driven by a drive signal (voltage) of a predetermined drive frequency.

[0030] Furthermore, there is no particular limitation on the relative position of the second position 20B of the second ultrasonic element 40 with respect to the first position 20A of the first ultrasonic element 30. However, it is preferable that the distance between the second ultrasonic element 40 and the first ultrasonic element 30 does not affect the generation of the standing wave SW. Additionally, it is preferable that the fluid S flowing at the first position 20A and the fluid S flowing at the second position 20B have the same temperature; for example, the first position 20A and the second position 20B are within a distance range that does not create a temperature difference between them. It should be noted that when the distance between the first position 20A and the second position 20B is large, it is preferable to set the surrounding environment at the first position 20A and the second position 20B so that the temperature of the fluid S is the same.

[0031] The control unit 50 includes a continuous wave generation circuit 51, an impedance measurement circuit 52, a memory 53, and one or more processors 54 that control the first ultrasonic element 30 and the second ultrasonic element 40 by means of the respective circuits.

[0032] The continuous wave generating circuit 51 corresponds to the first driving unit of this disclosure, generating a first driving signal output to the first ultrasonic element 30. This continuous wave generating circuit 51 is a circuit capable of changing the driving frequency of the output first driving signal. Based on the control of the processor 54, it generates a first driving signal with the driving frequency set to a predetermined first driving frequency Fd, and continuously outputs it to the first ultrasonic element 30.

[0033] The impedance measurement circuit 52 corresponds to the second drive unit of this disclosure, generating a second drive signal output to the second ultrasonic element 40. This impedance measurement circuit 52 is a circuit capable of changing the drive frequency of the output second drive signal, generating a drive signal of arbitrary drive frequency according to measurement instructions from the processor 54, and outputting it to the second ultrasonic element 40. Furthermore, the impedance measurement circuit 52 measures the impedance of the second ultrasonic element 40. For example, it includes a galvanometer that measures the current flowing in the second ultrasonic element 40, and measures the impedance of the second ultrasonic element 40 based on the voltage value of the second drive signal applied to the second ultrasonic element 40 and the current value measured by the galvanometer.

[0034] The memory 53 is a storage device for storing various programs and data. For example, the memory 53 stores the value of the first driving frequency Fd of the current first driving signal of the first ultrasonic element 30.

[0035] The processor 54 functions as a measurement control unit 541 that outputs measurement commands to the impedance measurement circuit 52 and a drive control unit 542 that controls the first drive frequency Fd of the first ultrasonic element 30 by executing the program stored in the memory 53.

[0036] Control mechanism of fluid equipment

[0037] Next, the mechanism and method for capturing microparticles M at the nodes of the standing wave SW at the first position 20A of the flow path 20 in the fluid device 10 of this embodiment will be described.

[0038] If the frequency of the ultrasonic wave sent to the fluid is set as f, the number of standing waves formed by the ultrasonic wave is set as m, the sound velocity in the fluid is set as c, and the flow path width along the Y-axis is set as L, then in order to form a standing wave SW at the first position 20A, the frequency f of the ultrasonic wave output from the first ultrasonic element 30 needs to satisfy the following condition (1).

[0039] Number 1

[0040]

[0041] As the temperature in the fluid changes, the velocity of sound c in the fluid S changes, and thus the frequency f used to form the standing wave SW also changes.

[0042] On the other hand, if a standing wave SW is formed in the flow path 20, the sound pressure will increase at the antinode of the standing wave SW. Therefore, the impedance when driving the first ultrasonic element 30 and the second ultrasonic element 40 will also increase.

[0043] Figure 2 A graph showing the change in impedance of the second ultrasonic element 40 when the driving frequency of the second driving signal is changed.

[0044] like Figure 2 As shown, although the impedance of the second ultrasonic element 40 gradually decreases by increasing the driving frequency of the second driving signal, the peak points Pn (n = 1, 2, 3...) when the impedance is at its maximum value appear at predetermined intervals. These peak points Pn are visible when the standing wave SW is formed within the flow path 20, and the position of the antinode when the sound pressure of the standing wave SW is at its maximum is shown to be located at the ultrasonic transmitting surface 40S of the second ultrasonic element 40.

[0045] That is, even when the sound velocity c changes due to the temperature of the fluid S, the optimal driving frequency for forming the standing wave SW can be determined by detecting the peak point Pn of the impedance of the second ultrasonic element 40.

[0046] Furthermore, in this embodiment, the flow path width L at the second position 20B of the second ultrasonic element 40 is the same as the flow path width L at the first position 20A of the first ultrasonic element 30, and the temperatures of the fluid S at the first position 20A and the second position 20B are also the same. Therefore, the conditions for the driving frequency used to form a standing wave SW at the second position 20B are consistent with the conditions for the driving frequency used to form a standing wave SW at the first position 20A.

[0047] Control methods for fluid equipment

[0048] Next, the control method of the fluid device 10 in this embodiment will be described.

[0049] Figure 3 A flowchart illustrating the control method of the fluid device 10 according to this embodiment is provided.

[0050] In this embodiment, the frequency of the ultrasonic waves output from the first ultrasonic element 30 is controlled by feedback based on the impedance measurement results of the second ultrasonic element 40. The impedance measurement of the second ultrasonic element 40 can be performed periodically, for example, it can be performed when the fluid device 10 is started.

[0051] exist Figure 3 The example shown illustrates an instance where the impedance of the second ultrasonic element 40 is measured periodically.

[0052] That is, the drive control unit 542 of the control unit 50 reads the first drive frequency Fd recorded in the memory 53 and outputs a drive command indicating that the first ultrasonic element 30 is driven by the first drive signal of the first drive frequency Fd to the continuous wave generation circuit 51 (step S1).

[0053] Therefore, the continuous wave generating circuit 51 continuously outputs a first driving signal with a first driving frequency Fd to the first ultrasonic element 30, and sends a continuous wave with the first driving frequency from the first ultrasonic element 30 to the fluid S (step S2). At this time, when the first driving frequency Fd satisfies the optimal conditions for forming a standing wave SW, microparticles M are captured at the position of the node of the standing wave SW formed at the first position 20A.

[0054] Then, when the predetermined measurement timing is reached (step S3: Yes), the measurement control unit 541 outputs an impedance measurement command to the impedance measurement circuit 52 and measures the change in impedance in the second ultrasonic element 40 (step S4). When the measurement timing is not reached, the transmission of continuous waves in step S2 continues.

[0055] When a measurement command is input to the impedance measurement circuit 52, the impedance measurement circuit 52 outputs a second drive signal to the second ultrasonic element 40 and causes the drive frequency of the second drive signal to vary within a predetermined range. Then, the impedance measurement circuit 52 measures the change in impedance of the second ultrasonic element 40 caused by the change in the drive frequency of the second drive signal.

[0056] The predetermined range refers to the range corresponding to the number m of the standing wave SW formed in the flow path 20. Figure 4 A graph showing the relationship between the driving frequency and the impedance of the second ultrasonic element 40 when the temperature of the fluid S changes.

[0057] For example, in Figure 2 In the process, when a standing wave SW with a frequency m of 3 is formed, a peak point P3 appears near 1570 kHz. Although the driving frequency corresponding to the peak point P3 changes when the temperature of the fluid S changes, as... Figure 4 As shown, the frequency variation range is within ±10kHz. Therefore, in this case, as a predetermined range, it is sufficient to vary the driving frequency within the range of 1560kHz to 1580kHz.

[0058] It should be noted that the predetermined range of the driving frequency of the second driving signal can be appropriately set according to the allowable temperature range of the fluid S flowing in the flow path 20 and the number of times m is set as the peak point of the detection object. For example, when the allowable temperature range of the fluid S flowing in the flow path 20 is 20℃~40℃ and the number of times m is 3, such as Figure 4 As shown, the driving frequency can be varied within a range of ±10kHz centered at 1570kHz. Furthermore, to further expand the permissible temperature range of the fluid S, the range of variation of the driving frequency of the second driving signal can be further expanded.

[0059] In addition, when changing the driving frequency of the second driving signal, the impedance measurement circuit 52 can, for example, sweep the driving frequency within a predetermined range, or change the driving frequency sequentially at predetermined intervals (e.g., 1 kHz intervals).

[0060] Then, the measurement control unit 541 determines the driving frequency (second driving frequency Fs) of the second driving signal when the impedance of the second ultrasonic element 40 is at its maximum based on the impedance measurement result output from the impedance measurement circuit 52 (step S5). As described above, if the range of variation of the driving frequency is small (a narrow range of ±10kHz), the driving frequency at which the maximum impedance is reached can be determined as the second driving frequency Fs. It should be noted that when the range of variation of the driving frequency is wider, for example, when the driving frequency is varied in the range of 500kHz to 3000kHz, multiple maxima (peak points Pn) are detected based on the impedance change, and the second driving frequency Fs corresponding to the desired number m is determined based on each peak point Pn.

[0061] Then, the drive control unit 542 determines whether the current first drive frequency Fd is consistent with the second drive frequency Fs determined in step S5 (step S6). Here, "consistency" is defined as including not only that the first drive frequency Fd and the second drive frequency Fs are completely consistent, but also that there is a slight error within the range of the standing wave SW. That is, in step S6, when |Fd - Fs| is within a preset error range, it is determined that the two are consistent.

[0062] If the determination in step S6 is negative, the drive control unit 542 rewrites the first drive frequency Fd recorded in the memory 53 with the second drive frequency Fs determined in step S5 to update it (step S7), and returns to step S1. That is, in step S1, the first ultrasonic element 30 is driven by the updated first drive frequency Fd. Therefore, in step S2, the first ultrasonic element 30 is driven by the optimal first drive frequency Fd used to form the standing wave SW.

[0063] When the determination is yes in step S6, the first ultrasonic element 30 continues to be driven by the first drive signal at the current first drive frequency Fd. That is, the first drive frequency Fd is not updated, and the driving of the first ultrasonic element 30 in step S2 continues in a unchanged state.

[0064] Then, the control unit 50 determines whether to continue forming the standing wave SW (step S8). For example, if an input indicating the end of processing is received through user settings, etc., it is determined to be no in step S8, and the operation of the fluid device 10 is stopped. If it is determined to be yes in step S8, the process returns to step S2. That is, the operation of the first ultrasonic element 30 in step S2 continues.

[0065] It should be noted that, in Figure 3 Although step S8 is implemented after step S6 determines that it is true, step S8 can also be implemented at any time.

[0066] In addition, Figure 3 In the example shown, in step S1, the first driving frequency Fd stored in memory 53 is read to drive the first ultrasonic element 30. That is, the first driving frequency Fd measured during the last operation of the fluid device 10 is used immediately after the fluid device 10 is started. Alternatively, steps S4 to S7 can be performed before step S1, and the optimal first driving frequency Fd for forming the standing wave SW can be set initially.

[0067] The effect of this implementation method

[0068] The fluid device 10 of this embodiment includes: a flow path 20 extending along the X-axis (first axis), through which fluid S flows; a first ultrasonic element 30 and a second ultrasonic element 40 disposed in the flow path 20 and transmitting ultrasonic waves into the flow path 20 along the Y-axis (second axis) via an input drive signal; and a control unit 50. The control unit 50 varies the drive frequency of the second drive signal within a predetermined range to measure the impedance of the second ultrasonic element 40 when it is driven, determines the drive frequency at which the impedance is at its maximum and sets it as the first drive frequency, and inputs the first drive signal of the first drive frequency to the first ultrasonic element 30.

[0069] The fluid device 10 generates a standing wave SW in the fluid S within the flow path 20 via a first ultrasonic element 30. However, since the sound velocity in the fluid S changes when the temperature of the fluid S changes, the conditions for forming the standing wave SW also change. Therefore, in this embodiment, as described above, the impedance of the second ultrasonic element 40 is measured while the driving frequency of the second ultrasonic element 40 is varied. In this case, the driving frequency (second driving frequency Fs) at which the impedance is at its maximum can be determined as the first driving frequency Fd used to form the standing wave SW. Therefore, even when the fluid temperature and sound velocity change, the driving frequency of the first driving signal of the first ultrasonic element 30 can be feedback-controlled according to the temperature change. As a result, a standing wave SW can be stably generated even when the fluid temperature changes.

[0070] In this embodiment, the first ultrasonic element 30 is disposed at the first position 20A of the flow path 20, and transmits ultrasonic waves along the Y-axis upon input of a first drive signal. The second ultrasonic element 40 is disposed at the second position 20B of the flow path 20, and transmits ultrasonic waves along the Y-axis upon input of a second drive signal. Furthermore, the first position 20A and the second position 20B of the flow path 20 have the same flow path width L. As described above, the control unit 50 varies the drive frequency of the second drive signal input to the second ultrasonic element 40 within a predetermined range to measure the impedance of the second ultrasonic element 40, determines the drive frequency (second drive frequency Fs) when the impedance is at its maximum, and sets it as the first drive frequency Fd. That is, when the first drive frequency Fd already recorded in the memory 53 is inconsistent with the determined second drive frequency Fs, the determined second drive frequency Fs is recorded as the new first drive frequency Fd in the memory 53. Then, the control unit 50 inputs the first drive signal of the new first drive frequency Fd to the first ultrasonic element 30.

[0071] In flow path 20, since the flow path width L is the same at the first position 20A where the first ultrasonic element 30 is disposed and at the second position 20B where the second ultrasonic element 40 is disposed, the frequency f of the ultrasonic wave used to form a standing wave SW at the first position 20A is the same as the frequency f of the ultrasonic wave used to form a standing wave at the second position 20B, as shown in equation (1). Therefore, the first driving frequency Fd for driving the first ultrasonic element 30 can be set based on the impedance of the second ultrasonic element 40 disposed at the second position 20B.

[0072] Therefore, by separating the second ultrasonic element 40 for measuring impedance from the first ultrasonic element 30 for forming a standing wave SW, it is possible to measure the impedance in the second ultrasonic element 40 while the standing wave SW is still being formed at the first position 20A, and to perform feedback control on the first ultrasonic element 30 based on the measurement result.

[0073] In this embodiment, the control unit 50 includes a continuous wave generating circuit 51 serving as a first driving unit and an impedance measuring circuit 52 serving as a second driving unit. The continuous wave generating circuit 51 is a circuit that outputs a first driving signal to the first ultrasonic element 30 and is capable of changing the driving frequency of the first driving signal. The impedance measuring circuit 52 is a circuit that outputs a second driving signal to the second ultrasonic element 40 and is capable of changing the driving frequency of the second driving signal within a predetermined range, and measures the impedance of the second ultrasonic element 40 when the driving frequency of the second driving signal is changed within the predetermined range.

[0074] In this embodiment, the first ultrasonic element 30 can be driven by the continuous wave generation circuit 51 while the impedance of the second ultrasonic element 40 is measured by the impedance measurement circuit 52. That is, in this embodiment, a standing wave SW can be continuously formed at the first position 20A while feedback control is performed based on the impedance of the second ultrasonic element 40 located at the second position 20B.

[0075] Furthermore, in this embodiment, by using water as the fluid S, a fluid device 10 capable of properly separating microparticles M contained in water can be provided, thus expanding its application range. For example, by allowing domestic wastewater from a washing machine or kitchen to flow into the fluid device 10, microparticles contained in the wastewater can be separated. In this case, fine plastic fibers contained in laundry water, abrasive powders from detergents contained in kitchen wastewater, etc., can be separated, and environmental hazards caused by substances such as plastic waste can also be suppressed. However, the fluid S is not limited to water. For example, by using blood as the fluid S, a fluid device 10 capable of separating cellular components contained in the blood can be provided. In the case where the cellular component is cancer cells in the blood, cancer cells contained in the blood can be separated and removed, and cancer metastasis can also be suppressed.

[0076] Second Implementation Method

[0077] Next, the fluid device of the second embodiment will be described.

[0078] In the first embodiment described above, an example is shown where the ultrasonic transmitting unit of this disclosure includes a first ultrasonic element 30 and a second ultrasonic element 40. A standing wave SW is generated within the flow path 20 by the first ultrasonic element 30, and the optimal driving frequency is determined using the impedance of the second ultrasonic element 40. In contrast, in the second embodiment, the difference from the first embodiment is that the ultrasonic transmitting unit is composed of a single ultrasonic element.

[0079] Figure 5 The figure illustrates the fluid device 10A of the second embodiment. It should be noted that in the following description, the same reference numerals as those already described will be omitted or simplified.

[0080] Similar to the first embodiment, the fluid device 10A has a flow path 20, and a third ultrasonic element 60, which is identical to the first ultrasonic element 30, is provided at a predetermined position in the flow path 20. That is, the third ultrasonic element 60 is provided on the first wall 21 such that the ultrasonic transmitting surface 60S forms part of the first wall 21 in the flow path 20, and transmits ultrasonic waves toward the second wall 22 along the Y-axis.

[0081] In addition to a continuous wave generation circuit 51, an impedance measurement circuit 52, a memory 53, and a processor 54, the control unit 50A also includes a switching unit 55.

[0082] The switching unit 55 is connected to the continuous wave generating circuit 51, the impedance measuring circuit 52, and the third ultrasonic element 60. Furthermore, the switching unit 55 can switch between a drive mode connection connecting the continuous wave generating circuit 51 and the third ultrasonic element 60 and a measurement mode connection connecting the impedance measuring circuit 52 and the third ultrasonic element 60, and these connections are switched under the control of the processor 54.

[0083] The processor 54 functions as the measurement control unit 541, drive control unit 542, and mode switching unit 543 by executing the program stored in the memory 53.

[0084] In this embodiment, the mode switching unit 543 switches the connection state of the switching unit 55 to measurement mode connection and drive mode connection.

[0085] Furthermore, when the switching unit 55 switches to the measurement mode connection via the mode switching unit 543, the measurement control unit 541 outputs a measurement command to the impedance measurement circuit 52. As a result, the impedance measurement circuit 52 sweeps the drive frequency of the drive signal input to the third ultrasonic element 60 within a predetermined range and measures the impedance of the third ultrasonic element 60.

[0086] Furthermore, when the switching unit 55 switches to drive mode connection via the mode switching unit 543, the drive control unit 542 outputs a drive command to the continuous wave generation circuit 51 indicating that a drive signal of the first drive frequency Fd will be output to the third ultrasonic element 60. Thus, ultrasonic waves of the optimal drive frequency for forming a standing wave SW are output from the third ultrasonic element 60.

[0087] Control methods for fluid equipment

[0088] Next, the control method of the fluid device 10A according to the second embodiment will be described. Figure 6 A flowchart illustrating the control method of the fluid device 10A according to the second embodiment.

[0089] In this embodiment, the frequency of the ultrasonic wave output from the third ultrasonic element 60 is controlled by feedback based on the impedance measurement result measured in measurement mode. The impedance measurement of the third ultrasonic element 60 can be performed periodically, for example, when the fluid device 10A is started.

[0090] exist Figure 6 The example shown illustrates an instance where the impedance of the third ultrasonic element 60 is measured periodically.

[0091] In this embodiment, firstly, the mode switching unit 543 switches the operating mode to the drive mode. That is, the mode switching unit 543 switches the switching unit 55 to drive mode connection and connects the third ultrasonic element 60 and the continuous wave generating circuit 51 (step S11).

[0092] After that, similar to step S1 of the first embodiment, the drive control unit 542 reads the first drive frequency Fd recorded in the memory 53 and outputs a drive command indicating that the third ultrasonic element 60 is driven by the drive signal of the first drive frequency Fd to the continuous wave generation circuit 51 (step S12).

[0093] Therefore, similar to step S2, the continuous wave generating circuit 51 continuously outputs the first driving signal of the first driving frequency Fd to the third ultrasonic element 60, and sends the continuous wave of the first driving frequency Fd from the third ultrasonic element 60 to the fluid S (step S13).

[0094] After this, the mode switching unit 543 determines whether the predetermined measurement time has been reached (step S14). When the measurement time has been reached (step S14: Yes), the operating mode is switched to the measurement mode. That is, the mode switching unit 543 switches the switching unit 55 to the measurement mode connection and connects the third ultrasonic element 60 and the impedance measurement circuit 52 (step S15).

[0095] Then, similar to step S4, the measurement control unit 541 outputs a measurement command for impedance to the impedance measurement circuit 52, and measures the change in impedance in the third ultrasonic element 60 (step S16).

[0096] In addition, similar to step S5, the measurement control unit 541 determines the driving frequency (second driving frequency Fs) of the driving signal output to the third ultrasonic element 60 at a time when the impedance of the third ultrasonic element 60 is extremely large based on the impedance measurement result output from the impedance measurement circuit 52 (step S17).

[0097] After this, the same processing as steps S6 to S8 of the first embodiment is performed. That is, in step S6, it is determined whether the current first driving frequency Fd is consistent with the second driving frequency Fs determined in step S17. If it is determined not to be consistent in step S6, in step S7, the first driving frequency Fd recorded in the memory 53 is updated and the process returns to step S11. Thus, after switching to the driving mode in step S11, in step S12, a driving command indicating that the third ultrasonic element 60 is driven by the updated first driving frequency Fd is output to the continuous wave generation circuit 51. In step S13, a standing wave SW is formed in the fluid S by the third ultrasonic element 60.

[0098] If the determination in step S6 is yes, the process in step S8 determines whether to continue forming a standing wave SW. If it continues (step S8: yes), the process returns to step S11. That is, the first driving frequency Fd is not updated, and the operating mode is switched to driving mode. It should be noted that, similar to the first embodiment, the process in step S8 can also be implemented at any time.

[0099] In addition, Figure 6 In the example shown, after the driving mode is implemented in steps S11 to S13, steps S14 to S17 and steps S6 to S7 are performed, but this is not a limitation. For example, it is also possible that step S14 is performed to switch to measurement mode before step S11, the impedance measurement processing in steps S13 to S17 and the first driving frequency update processing in steps S6 to S7 are performed, and then the switching to driving mode is performed in step S11.

[0100] The effect of this implementation method

[0101] In the fluid device 10A of this embodiment, the ultrasonic transmitting unit is composed of a single third ultrasonic element 60. Furthermore, the control unit 50A implements a measurement mode in which the drive frequency of the drive signal is varied within a predetermined range and input to the third ultrasonic element 60, and a drive mode in which the drive frequency of the drive signal is fixed and input to the third ultrasonic element 60. In the measurement mode, the impedance of the third ultrasonic element 60 is measured, and the drive frequency at which the impedance is at its maximum is determined and set as the first drive frequency. In the drive mode, a drive signal at the first drive frequency Fd set in the measurement mode is input to the third ultrasonic element 60.

[0102] In this case, the formation of the standing wave SW and the measurement of impedance for setting the optimal driving frequency (first driving frequency Fd) can be implemented by a single third ultrasonic element 60, which simplifies the configuration of the ultrasonic equipment.

[0103] In this embodiment, the control unit 50A includes a continuous wave generation circuit 51, an impedance measurement circuit 52, and a switching unit 55.

[0104] Therefore, by switching the switching unit 55 to drive mode connection, a standing wave SW can be formed in the flow path 20 by the third ultrasonic element 60, and by switching the switching unit 55 to measurement mode connection, the impedance of the third ultrasonic element 60 can be measured to determine a first drive frequency Fd suitable for forming the standing wave SW.

[0105] Variations

[0106] This invention is not limited to the embodiments described above. Modifications, improvements, and configurations obtained by appropriately combining the embodiments are all included in this invention, within the scope of achieving the purpose of this invention.

[0107] Variation Example 1

[0108] In the first embodiment, a second driving frequency Fs based on the impedance measured by the second ultrasonic element 40 is stored as a first driving frequency Fd in the memory 53, and the drive control unit 542 reads the first driving frequency Fd to drive the first ultrasonic element 30, but this is not limited to this. It can also be configured such that, when the second driving frequency Fs is obtained, the drive control unit 542 outputs a drive command to set the second driving frequency Fs as the first driving frequency Fd to the continuous wave generation circuit 51.

[0109] Variation Example 2

[0110] In the first embodiment, a configuration in which a first ultrasonic element 30 and a second ultrasonic element 40 are disposed on the first wall surface 21 is illustrated. In the second embodiment, a configuration in which a third ultrasonic element 60 is disposed on the first wall surface 21 is illustrated, but the embodiment is not limited to these configurations.

[0111] For example, it can also be configured such that the first ultrasonic element 30, the second ultrasonic element 40, and the third ultrasonic element 60 are disposed on the second wall surface 22.

[0112] Furthermore, when ultrasonic waves are emitted from the first ultrasonic element 30, the second ultrasonic element 40, and the third ultrasonic element 60, the ultrasonic waves diffuse and propagate outwards from the ultrasonic emission surfaces 30S, 40S, and 60S. Therefore, the first ultrasonic element 30, the second ultrasonic element 40, and the third ultrasonic element 60 can also be configured to be disposed on a side orthogonal to the first wall surface 21 and the second wall surface 22, such as the bottom surface of a groove in a base substrate or a cover substrate. In this case, the first ultrasonic element 30, the second ultrasonic element 40, and the third ultrasonic element 60 can be positioned at the antinodes of the standing wave SW.

[0113] Variation Example 3

[0114] In the first embodiment, the first ultrasonic element 30 and the second ultrasonic element 40 are respectively formed on the flow path wall of the flow path 20, but this is not a limitation. For example, the wall component of the flow path 20 can be disposed between the first ultrasonic element 30 and the fluid S, or the wall component of the flow path 20 can be disposed between the second ultrasonic element 40 and the fluid S. The same applies to the third ultrasonic element 60 in the second embodiment.

[0115] This is a summary of the disclosure.

[0116] The fluid apparatus of the first aspect of this disclosure comprises: a flow path extending along a first axis, wherein a fluid flows within the flow path; an ultrasonic transmitter disposed in the flow path and transmitting ultrasonic waves within the flow path along a second axis orthogonal to the first axis via an input of a drive signal; and a control unit controlling the ultrasonic transmitter, wherein the control unit causes the drive frequency of the drive signal to vary within a predetermined range to measure the impedance of the ultrasonic transmitter when the ultrasonic transmitter is driven, determines the drive frequency at which the impedance is at its maximum and sets it as a first drive frequency, and inputs the drive signal at the first drive frequency to the ultrasonic transmitter.

[0117] When a standing wave is formed by the ultrasonic transmitter, the transmitter is located at the antinode of the standing wave. Because the sound pressure is extremely high at the antinode of the standing wave, the impedance when driving the ultrasonic transmitter is also extremely high. Therefore, as described above, by measuring the impedance of the ultrasonic transmitter while changing its driving frequency, it is possible to determine whether a standing wave has been formed. In other words, it can be determined that when the ultrasonic transmitter is driven at the driving frequency where the impedance is extremely high, a standing wave is formed in the flow path, and the sound pressure in the ultrasonic transmitter is extremely high. Therefore, even when the fluid temperature and sound velocity change, the first driving frequency of the driving signal used to form the standing wave can be determined, and the frequency of the ultrasonic waves transmitted from the ultrasonic transmitter can be feedback controlled according to the temperature change. As a result, a standing wave can be stably generated even when the fluid temperature changes.

[0118] In a fluid apparatus of the first aspect, the ultrasonic transmitting unit includes: a first ultrasonic element disposed at a first position in the flow path, transmitting ultrasonic waves along a second axis via an input of a first drive signal; and a second ultrasonic element disposed at a second position, transmitting ultrasonic waves along the second axis via an input of a second drive signal, wherein the position of the second position along the first axis is different from that of the first position in the flow path, and the width of the flow path along the second axis at the first position is the same as the width along the second axis at the second position. The control unit causes the drive frequency of the second drive signal input to the second ultrasonic element to vary within a predetermined range to measure the impedance of the second ultrasonic element when it is driven, sets the drive frequency at which the impedance of the second ultrasonic element is at its maximum as the first drive frequency, and sets the drive frequency of the first drive signal as the first drive frequency and inputs it to the first ultrasonic element.

[0119] In this aspect, the flow path width along the second axis is the same at the first position where the first ultrasonic element is set and the second position where the second ultrasonic element is set, and the conditions for the formation of standing waves are the same at both positions. Therefore, by measuring the change in impedance of the second ultrasonic element when the driving frequency of the second driving signal input to the second ultrasonic element changes, the conditions for the formation of standing waves at the first position can be determined. That is, by determining the driving frequency at which the impedance of the second ultrasonic element is at its maximum and setting it as the first driving frequency, and applying a first driving signal at the first driving frequency to the first ultrasonic element, a standing wave can be reasonably formed at the first position.

[0120] Therefore, by separating the second ultrasonic element that measures impedance from the first ultrasonic element that forms a standing wave, it is possible to measure the impedance in the second ultrasonic element while a standing wave continues to form at the first position, and to perform feedback control on the first ultrasonic element based on the measurement result.

[0121] In a fluid apparatus according to a first aspect, the control unit includes: a first drive unit that outputs a first drive signal and is capable of changing the drive frequency of the first drive signal, the first drive unit being connected to a first ultrasonic element; and a second drive unit that outputs a second drive signal and is capable of changing the drive frequency of the second drive signal, the second drive unit being connected to a second ultrasonic element, and measuring the impedance of the second ultrasonic element when the drive frequency of the second drive signal is changed within the predetermined range.

[0122] As described above, when a first ultrasonic element and a second ultrasonic element are arranged in the flow path, a first driving unit for driving the first ultrasonic element and a second driving unit for driving the second ultrasonic element and measuring the impedance of the second ultrasonic element are arranged in the control unit. Therefore, by separating the first driving unit for driving the first ultrasonic element and the second driving unit for driving the second ultrasonic element, it is possible to measure the impedance of the second ultrasonic element while a standing wave continues to form at the first position through the first ultrasonic element.

[0123] In the fluid device of the first aspect, the ultrasonic transmitting unit may also be configured such that the ultrasonic transmitting unit is a single ultrasonic element, and the control unit implements: a measurement mode in which the driving frequency of the driving signal is varied within a predetermined range and input to the ultrasonic element; and a driving mode in which the driving frequency of the driving signal is fixed and input to the ultrasonic element. In the measurement mode, the impedance of the ultrasonic element is measured, the driving frequency when the impedance is at its maximum is determined and set as the first driving frequency, and in the driving mode, the driving frequency of the driving signal is fixed to the first driving frequency and input to the ultrasonic element.

[0124] In this case, the formation of standing waves and the measurement of impedance for setting the optimal driving frequency can be achieved through a single ultrasonic element, which simplifies the configuration of the ultrasonic equipment.

[0125] In the fluid apparatus of the first aspect, the control unit includes: a first drive unit that outputs the drive signal and is capable of changing the drive frequency of the drive signal; a second drive unit that outputs the drive signal and is capable of changing the drive frequency of the drive signal, and measures the impedance of the ultrasonic transmitter when the drive frequency of the drive signal is changed within a predetermined range; and a switching unit that is connected to the first drive unit, the second drive unit, and the ultrasonic transmitter, and is capable of switching between a drive mode connection between the first drive unit and the ultrasonic transmitter and a measurement mode connection between the second drive unit and the ultrasonic transmitter.

[0126] As described above, when the ultrasonic transmitting unit is constructed using a single ultrasonic element, a first driving unit for forming a standing wave, a second driving unit for measuring impedance, and a switching unit are provided in the control unit. Therefore, by switching the switching unit to driving mode connection, a standing wave can be formed within the flow path by the ultrasonic element, and by switching the switching unit to measurement mode connection, the impedance of the ultrasonic element can be measured to determine a first driving frequency suitable for forming the standing wave.

[0127] The second aspect of this disclosure relates to a control method for a fluid device for capturing microparticles in a fluid flowing inside a flow path extending along a first axis. The fluid device includes an ultrasonic transmitter disposed in the flow path, which transmits ultrasonic waves along a second axis orthogonal to the first axis within the flow path via an input of a drive signal. In the control method, the drive frequency of the drive signal is varied within a predetermined range to measure the impedance of the ultrasonic transmitter when it is driven. A drive frequency at which the impedance is at its maximum is determined and set as a first drive frequency. The drive signal at the first drive frequency is then input to the ultrasonic transmitter.

[0128] Thus, similar to the first aspect of this disclosure, standing waves can be stably generated even when the temperature of the fluid changes.

[0129] In the control method of the fluid device in the second aspect, the ultrasonic transmitting unit includes: a first ultrasonic element disposed at a first position in the flow path, transmitting ultrasonic waves along a second axis via an input of a first driving signal; and a second ultrasonic element disposed at a second position, transmitting ultrasonic waves along the second axis via an input of a second driving signal, wherein the position of the second position along the first axis is different from that of the first position in the flow path, and the width of the flow path along the second axis at the first position is the same as the width along the second axis at the second position. In the control method of the fluid device, the driving frequency of the second driving signal input to the second ultrasonic element is varied within a predetermined range to measure the impedance of the second ultrasonic element when driving it, the driving frequency when the impedance is at its maximum is set as the first driving frequency, and the driving frequency of the first driving signal is set as the first driving frequency and input to the first ultrasonic element.

[0130] Therefore, by separating the second ultrasonic element that measures impedance from the first ultrasonic element that forms a standing wave, it is possible to measure the impedance in the second ultrasonic element while a standing wave continues to form at the first position, and to perform feedback control on the first ultrasonic element based on the measurement result.

[0131] In the control method of the fluid device in the second aspect, the ultrasonic transmitting unit may be a single ultrasonic element. In the control method of the fluid device, the following are implemented: a measurement mode in which the driving frequency of the driving signal is varied within a predetermined range and input to the ultrasonic element; and a driving mode in which the driving frequency of the driving signal is fixed and input to the ultrasonic element. In the measurement mode, the impedance of the ultrasonic element is measured, the driving frequency when the impedance is at its maximum is determined and set as the first driving frequency, and in the driving mode, the driving frequency of the driving signal is fixed to the first driving frequency and input to the ultrasonic element.

[0132] Therefore, the formation of standing waves and the measurement of impedance for setting the optimal driving frequency can be achieved through a single ultrasonic element, which simplifies the configuration of ultrasonic equipment.

Claims

1. A fluid device, characterized in that, have: A flow path extends along the first axis, and fluid flows within the flow path; An ultrasonic transmitting unit is disposed in the flow path and transmits ultrasonic waves within the flow path along a second axis orthogonal to the first axis via the input of a drive signal; as well as The control unit controls the ultrasonic transmitting unit. The control unit changes the driving frequency of the driving signal within a predetermined range to measure the impedance of the ultrasonic transmitter when driving the ultrasonic transmitter, determines the driving frequency when the impedance is at its peak and sets it as the first driving frequency, and inputs the driving signal at the first driving frequency to the ultrasonic transmitter.

2. The fluid device according to claim 1, characterized in that, The ultrasonic transmitting unit includes: A first ultrasonic element, disposed at a first position in the flow path, transmits ultrasonic waves along the second axis upon input of a first drive signal; and A second ultrasonic element, disposed at a second position, transmits ultrasonic waves along the second axis upon input of a second drive signal. The position of the second position along the first axis in the flow path differs from that of the first position. The width of the flow path along the second axis at the first position is the same as the width along the second axis at the second position. The control unit causes the driving frequency of the second driving signal input to the second ultrasonic element to vary within the predetermined range to measure the impedance of the second ultrasonic element when driving it. The driving frequency at which the impedance of the second ultrasonic element is at its peak is set as the first driving frequency. The driving frequency of the first driving signal is set as the first driving frequency and input to the first ultrasonic element.

3. The fluid device according to claim 2, characterized in that, The control unit includes: A first driving unit outputs the first driving signal and is capable of changing the driving frequency of the first driving signal. The first driving unit is connected to the first ultrasonic element. as well as The second driving unit outputs the second driving signal and is capable of changing the driving frequency of the second driving signal. The second driving unit is connected to the second ultrasonic element and measures the impedance of the second ultrasonic element when the driving frequency of the second driving signal is changed within the predetermined range.

4. The fluid device according to claim 1, characterized in that, The ultrasonic transmitter is a single ultrasonic element. The control unit implements: The measurement mode allows the driving frequency of the driving signal to vary within a predetermined range and be input to the ultrasonic element; as well as In the driving mode, the driving frequency of the driving signal is fixed and input to the ultrasonic element. In the measurement mode, the control unit measures the impedance of the ultrasonic element, determines the driving frequency at which the impedance reaches its peak value, and sets it as the first driving frequency. In the driving mode, the control unit fixes the driving frequency of the driving signal to the first driving frequency and inputs it to the ultrasonic element.

5. The fluid device according to claim 4, characterized in that, The control unit includes: The first driving unit outputs the driving signal and is capable of changing the driving frequency of the driving signal; The second driving unit outputs the driving signal and is capable of changing the driving frequency of the driving signal, and measures the impedance of the ultrasonic transmitting unit when the driving frequency of the driving signal is changed within the predetermined range; as well as The switching unit is connected to the first driving unit, the second driving unit, and the ultrasonic transmitting unit, and can switch between a driving mode connection connecting the first driving unit and the ultrasonic transmitting unit and a measurement mode connection connecting the second driving unit and the ultrasonic transmitting unit.

6. A control method for a fluid device, characterized in that, The control method of the fluid device is used to capture microparticles in the fluid flowing inside a flow path extending along a first axis. The fluid device includes an ultrasonic transmitting unit disposed in the flow path, which transmits ultrasonic waves along a second axis orthogonal to the first axis within the flow path upon input of a drive signal. In the control method of the fluid device. The driving frequency of the driving signal is varied within a predetermined range to measure the impedance of the ultrasonic transmitting unit when it is driven. The driving frequency at which the impedance reaches its peak value is determined and set as the first driving frequency. The driving signal at the first driving frequency is then input to the ultrasonic transmitting unit.

7. The control method for a fluid device according to claim 6, characterized in that, The ultrasonic transmitting unit includes: A first ultrasonic element, disposed at a first position in the flow path, transmits ultrasonic waves along the second axis upon input of a first drive signal; and A second ultrasonic element, disposed at a second position, transmits ultrasonic waves along the second axis upon input of a second drive signal. The position of the second position along the first axis in the flow path differs from that of the first position. The width of the flow path along the second axis at the first position is the same as the width along the second axis at the second position. In the control method of the fluid device. The driving frequency of the second driving signal input to the second ultrasonic element is varied within the predetermined range to measure the impedance of the second ultrasonic element when it is driven. The driving frequency when the impedance is at its peak is set as the first driving frequency. The driving frequency of the first driving signal is set as the first driving frequency and input to the first ultrasonic element.

8. The control method for a fluid device according to claim 6, characterized in that, The ultrasonic transmitter is a single ultrasonic element. In the control method of the fluid device, the following is implemented: The measurement mode allows the driving frequency of the driving signal to vary within a predetermined range and be input to the ultrasonic element; as well as In the driving mode, the driving frequency of the driving signal is fixed and input to the ultrasonic element. In the measurement mode, the impedance of the ultrasonic element is measured, and the driving frequency at which the impedance reaches its peak value is determined and set as the first driving frequency. In the driving mode, the driving frequency of the driving signal is fixed to the first driving frequency and input to the ultrasonic element.

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