Fluidic device and method for controlling fluidic device

1 . A fluidic device comprising:

a channel that extends along a first axis and through which a fluid flows;

an ultrasonic transmission part that is disposed at the channel and transmits an ultrasonic wave into the channel along a second axis orthogonal to the first axis in response to an input of a drive signal;

a first circuit;

a second circuit; and

a processor that:

controls the ultrasonic transmission part via at least one of the first circuit or the second circuit;

controls the second circuit to change a drive frequency of the drive signal within a predetermined range;

controls the second circuit to drive the ultrasonic transmission part by changing the drive frequency of the drive signal within the predetermined range;

controls the second circuit to measure impedance of the ultrasonic transmission part at a time when the ultrasonic transmission part is driven while changing the drive frequency of the drive signal within the predetermined range;

specifies a drive frequency at which the impedance is a local maximum;

sets the drive frequency at which the impedance is the local maximum as a first drive frequency; and

controls the first circuit to input the drive signal of the first drive frequency to the ultrasonic transmission part.

2 . The fluidic device according to claim 1 , wherein

the ultrasonic transmission part includes

a first ultrasonic element that is provided at a first position of the channel and transmits the ultrasonic wave along the second axis in response to an input of a first drive signal, and

a second ultrasonic element that is provided at a second position different in position from the first position in the channel in a direction along the first axis, and transmits the ultrasonic wave along the second axis in response to an input of a second drive signal,

a width of the channel along the second axis at the first position and a width of the channel along the second axis at the second position are the same, and

the processor:

controls the second circuit to change a drive frequency of the second drive signal within the predetermined range;

controls the second circuit to drive the second ultrasonic element by changing the drive frequency of the second drive signal within the predetermined range;

controls the second circuit to measure impedance of the second ultrasonic element at a time of driving the second ultrasonic element while changing the drive frequency of the second drive signal input to the second ultrasonic element within the predetermined range;

sets a drive frequency at which the impedance of the second ultrasonic element is the local maximum as the first drive frequency;

sets a drive frequency of the first drive signal to the first drive frequency; and

controls the first circuit to input the first drive signal of the first drive frequency to the first ultrasonic element.

3 . The fluidic device according to claim 2 , wherein

the first circuit:

outputs the first drive signal; and

changes the drive frequency of the first drive signal,

the first circuit is coupled to the first ultrasonic element, and

the second circuit:

outputs the second drive signal;

the drive frequency of the second drive signal, wherein the second circuit is coupled to the second ultrasonic element; and

measures the impedance of the second ultrasonic element at a time when the drive frequency of the second drive signal is changed within the predetermined range.

4 . The fluidic device according to claim 1 , wherein

the ultrasonic transmission part is a single ultrasonic element,

the processor operates in a measurement mode and a drive mode, and

the processor:

controls, in the measurement mode, the second circuit to change the drive frequency of the drive signal within the predetermined range;

controls, in the measurement mode, the second circuit to input the drive signal of a corresponding drive frequency to the single ultrasonic element;

fixes, in the drive mode, the drive frequency of the drive signal;

controls, in the drive mode, the first circuit to input the drive signal of the fixed drive frequency to the single ultrasonic element;

controls, in the measurement mode, the second circuit to measure impedance of the single ultrasonic element;

specifies, in the measurement mode, the drive frequency at which the impedance is the local maximum;

sets, in the measurement mode, the specified drive frequency as the first drive frequency;

fixes, in the drive mode, the drive frequency of the drive signal to the first drive frequency; and

controls, in the drive mode, the first circuit to input the drive signal of the first drive frequency to the single ultrasonic element.

5 . The fluidic device according to claim 4 , further comprising:

a switch part coupled to the first circuit, the second circuit, and the ultrasonic transmission part, wherein

the first circuit outputs the drive signal and is configured to change the drive frequency of the drive signal,

the second circuit:

outputs the drive signal;

changes the drive frequency of the drive signal; and

measure the impedance of the ultrasonic transmission part at a time when the drive frequency of the drive signal is changed within the predetermined range,

the switch part switches between a first coupling state and a second coupling state,

the switch part couples, in the first coupling state, the first circuit and the ultrasonic transmission part, and

the switch part couples, in the second coupling state, the second circuit and the ultrasonic transmission part.

6 . A method for controlling a fluidic device that captures a fine particle in a fluid flowing through a channel extending along a first axis,

the fluidic device including an ultrasonic transmission part that is disposed at the channel and transmits an ultrasonic wave into the channel along a second axis orthogonal to the first axis in response to input of a drive signal,

the fluidic device further including a first circuit, a second circuit, and a processor for controlling execution of the method, and

the method for controlling the fluidic device comprising:

controlling the ultrasonic transmission part via at least one of the first circuit or the second circuit;

controlling the second circuit to change a drive frequency of the drive signal within a predetermined range;

controlling the second circuit to drive the ultrasonic transmission part by changing the drive frequency of the drive signal within the predetermined range;

controlling the second circuit to measure impedance of the ultrasonic transmission part at a time when the ultrasonic transmission part is driven while changing the drive frequency of the drive signal within the predetermined range;

specifying a drive frequency at which the impedance is a local maximum;

setting the drive frequency at which the impedance is the local maximum as a first drive frequency; and

controlling the first circuit to input the drive signal of the first drive frequency to the ultrasonic transmission part.

7 . The method for controlling the fluidic device according to claim 6 ,

the ultrasonic transmission part including

a first ultrasonic element that is provided at a first position of the channel and transmits the ultrasonic wave along the second axis in response to an input of a first drive signal, and

a second ultrasonic element that is provided at a second position different in position from the first position in the channel in a direction along the first axis, and transmits the ultrasonic wave along the second axis in response to an input of a second drive signal, and

in the channel, a width along the second axis at the first position and a width along the second axis at the second position are the same,

the method further comprising:

controlling the second circuit to change a drive frequency of the second drive signal within the predetermined range;

controlling the second circuit to drive the second ultrasonic element by changing the drive frequency of the second drive signal within the predetermined range;

controlling the second circuit to measure impedance of the second ultrasonic element at a time when the second ultrasonic element is driven while changing the drive frequency of the second drive signal input to the second ultrasonic element within the predetermined range;

setting a drive frequency at which the impedance of the second ultrasonic element is the local maximum as the first drive frequency;

setting a drive frequency of the first drive signal to the first drive frequency; and

controlling the first circuit to input the first drive signal of the first drive frequency to the first ultrasonic element.

8 . The method for controlling the fluidic device according to claim 6 ,

the ultrasonic transmission part being a single ultrasonic element,

the processor operating in a measurement mode and a drive mode, and

the method comprising:

controlling, in the measurement mode, the second circuit to change the drive frequency of the drive signal within the predetermined range;

controlling, in the measurement mode, the second circuit to input the drive signal of a corresponding drive frequency to the single ultrasonic element;

fixing, in the drive mode, the drive frequency of the drive signal;

controlling, in the drive mode, the first circuit to input the drive signal of the fixed drive frequency to the single ultrasonic element;

controlling, in the measurement mode, the second circuit to measure impedance of the single ultrasonic element;

specifying, in the measurement mode, the drive frequency at which the impedance is the local maximum;

setting, in the measurement mode, the specified drive frequency as the first drive frequency;

fixing, in the drive mode, the drive frequency of the drive signal to the first drive frequency; and

controlling, in the drive mode, the first circuit to input the drive signal of the first drive frequency to the single ultrasonic element.