Control voltage correction method and dielectrophoresis apparatus

Abstract

To provide a control voltage correction method capable of executing correction of a control voltage while suppressing an increase in size of a fluid chip.SOLUTION: The control voltage correction method corrects a control voltage that causes a dielectrophoretic force to act on dielectric particles P1 contained in a first fluid injected into a fluid chip 11. The control voltage correction method includes: measuring S2 an impedance IM1 between first electrodes 43a, 43b in the fluid chip 11 through the first fluid or a second fluid; calculating S3 a correction coefficient based on the measured impedance IM1 and a fluid impedance IM2 derived by a mathematical formula; and correcting S4 a control voltage based on the correction coefficient. The fluid impedance IM2 indicates an impedance of the first fluid or the second fluid. The first fluid is a fluid containing the dielectric particles P1 and other particles P2. The second fluid is the same type of fluid as the fluid excluding the dielectric particles P1 and the other particles P2 from the first fluid.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a control voltage correction method and a dielectrophoretic device. [Background technology]

[0002] The fluid chip described in Patent Document 1 is a device that electrically separates and collects a target substance contained in a sample liquid. The fluid chip includes a substrate, a main flow path, a test flow path, a pair of main electrodes, and a pair of test electrodes. The main flow path is disposed on the upper surface of the substrate, and is capable of injecting a liquid. The test flow path is disposed on the upper surface of the substrate, and is spaced apart from the main flow path. The test flow path is capable of injecting a liquid. The pair of main electrodes are disposed between the upper surface of the substrate and the main flow path. The pair of test electrodes are disposed between the upper surface of the substrate and the test flow path.

[0003] Based on the inspection results of the inspection electrodes, a correction value can be obtained to correct for manufacturing variations. Then, the power supply unit applies a voltage corresponding to the correction value between the main electrodes. This allows a stable dielectrophoretic force to be applied to the collection target in the liquid injected into the main channel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-5958 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the fluid chip described in Patent Document 1, in order to correct the voltage (control voltage), it is necessary to provide an inspection electrode and an inspection flow path, which increases the size of the fluid chip.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a control voltage correction method and a dielectrophoresis device that can correct the control voltage while preventing the size of the fluid chip from increasing. [Means for solving the problem]

[0007] According to one aspect of the present invention, a control voltage correction method corrects a control voltage that exerts a dielectrophoretic force on dielectric particles contained in a first fluid injected into a fluidic chip. The control voltage correction method includes the steps of measuring an impedance between a pair of first electrodes in the fluidic chip via the first fluid or a second fluid, calculating a correction coefficient based on the measured impedance between the pair of first electrodes and a fluid impedance derived by a mathematical formula, and correcting the control voltage based on the correction coefficient. The fluid impedance indicates the impedance of the first fluid or the impedance of the second fluid. The first fluid is a fluid containing the dielectric particles and other particles. The second fluid is the same type of fluid as the first fluid excluding the dielectric particles and the other particles.

[0008] In one aspect of the present invention, the pair of first electrodes is preferably arranged downstream in the flow of the first fluid or the second fluid from the pair of second electrodes to which the control voltage is applied.

[0009] In one aspect of the present invention, the control voltage correction method preferably includes the steps of: capturing an image of the dielectric particles in a region downstream of the pair of second electrodes and upstream of the pair of first electrodes; and changing the correction coefficient based on the image of the dielectric particles. In the correcting step, the control voltage is preferably corrected based on the changed correction coefficient.

[0010] In one aspect of the present invention, when the dielectric particles are separated from the other particles by applying the control voltage to the pair of second electrodes, the changing step preferably includes a step of determining the frequency dependence of the separation rate of the dielectric particles based on the imaging results of the dielectric particles, and a step of changing the correction coefficient based on the frequency dependence of the separation rate of the dielectric particles.

[0011] In one aspect of the present invention, the control voltage correction method preferably further includes the steps of injecting the second fluid into the flow path of the fluidic chip, and injecting the first fluid into the flow path of the fluidic chip after injecting the second fluid into the flow path of the fluidic chip. In the measuring step, it is preferable to measure the impedance between the pair of first electrodes via the second fluid. In the calculating step, it is preferable to calculate the correction coefficient based on the impedance between the pair of first electrodes measured via the second fluid and the fluid impedance derived by the formula.

[0012] In one aspect of the present invention, the mathematical formula is preferably a theoretical formula or an empirical formula. The theoretical formula preferably includes the electrical resistivity or electrical conductivity of the first fluid or the electrical resistivity or electrical conductivity of the second fluid. The empirical formula is preferably a function determined by the electrical characteristics of the fluid chip and the dielectrophoretic characteristics of the dielectric particles.

[0013] In one aspect of the present invention, it is preferable that the correction coefficient is calculated each time the frequency of the control voltage is changed, and that the control voltage is corrected based on the correction coefficient calculated in response to a change in the frequency of the control voltage.

[0014] According to yet another aspect of the present invention, a dielectrophoresis device includes a fluid chip, a measurement unit, a correction coefficient calculation unit, and a voltage control unit. The fluid chip includes a pair of first electrodes, and a control voltage is applied to apply a dielectrophoretic force to dielectric particles contained in a first fluid. The measurement unit measures the impedance between the pair of first electrodes via the first fluid or the second fluid. The correction coefficient calculation unit calculates a correction coefficient based on the measured impedance between the pair of first electrodes and a fluid impedance derived by a mathematical formula. The voltage control unit corrects the control voltage based on the correction coefficient. The fluid impedance indicates the impedance of the first fluid or the impedance of the second fluid. The first fluid is a fluid containing the dielectric particles and other particles. The second fluid is the same type of fluid as the first fluid excluding the dielectric particles and the other particles.

[0015] In one aspect of the present invention, the fluidic chip preferably further includes a pair of second electrodes to which the control voltage is applied, and the pair of first electrodes is preferably arranged downstream of the pair of second electrodes in the flow of the first fluid or the second fluid.

[0016] In one aspect of the present invention, the dielectrophoresis device preferably further includes an imaging unit. The imaging unit preferably images the dielectric particles in a region downstream of the pair of second electrodes and upstream of the pair of first electrodes. The correction coefficient calculation unit preferably changes the correction coefficient based on the imaging result of the dielectric particles. The voltage control unit preferably corrects the control voltage based on the changed correction coefficient.

[0017] In one aspect of the present invention, when the dielectric particles are separated from the other particles by applying the control voltage to the pair of second electrodes, it is preferable that the correction coefficient calculation unit determines the frequency dependence of the separation rate of the dielectric particles based on the imaging results of the dielectric particles, and changes the correction coefficient based on the frequency dependence.

[0018] In one aspect of the present invention, the dielectrophoresis device preferably further includes a fluid injection unit. The fluid injection unit preferably injects the first fluid or the second fluid into the flow path of the fluidic chip. The fluid injection unit preferably injects the second fluid into the flow path of the fluidic chip, and then injects the first fluid into the flow path of the fluidic chip. The measurement unit preferably measures the impedance between the pair of first electrodes via the second fluid. The correction coefficient calculation unit preferably calculates the correction coefficient based on the impedance between the pair of first electrodes measured via the second fluid and the fluid impedance derived by the formula.

[0019] In one aspect of the present invention, the mathematical formula is preferably a theoretical formula or an empirical formula. The theoretical formula preferably includes the electrical resistivity or electrical conductivity of the first fluid or the electrical resistivity or electrical conductivity of the second fluid. The empirical formula is preferably a function determined by the electrical characteristics of the fluid chip and the dielectrophoretic characteristics of the dielectric particles.

[0020] In one aspect of the present invention, it is preferable that the correction coefficient calculation unit calculates the correction coefficient each time the frequency of the control voltage is changed, and the voltage control unit corrects the control voltage based on the correction coefficient calculated in response to the change in the frequency of the control voltage. [Effects of the Invention]

[0021] According to the present invention, it is possible to correct the control voltage while suppressing an increase in the size of the fluidic chip. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a plan view showing a dielectrophoresis device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of the fluidic chip taken along line II-II in FIG. 1. [Figure 3]FIG. 2 is a schematic cross-sectional view of the fluidic chip taken along line III-III in FIG. 1. [Figure 4] FIG. 2 is a block diagram showing a control unit according to the present embodiment. [Figure 5] 4 is a flowchart showing a control voltage correction method according to the present embodiment. [Figure 6] 10 is a graph showing an example of a correction coefficient according to the present embodiment. [Figure 7] FIG. 10 is a plan view showing a dielectrophoresis device according to a first modified example of the present embodiment. [Figure 8] 10 is a flowchart showing a control voltage correction method according to a first modified example of the present embodiment. [Figure 9] 10 is a graph showing the frequency dependency of the separation rate of dielectric particles according to the first modified example of the present embodiment. [Figure 10] 10 is a flowchart showing a control voltage correction method according to a second modification of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated. In addition, in this specification, mutually orthogonal X-axis, Y-axis, and Z-axis may be described to facilitate understanding of the invention. Typically, the X-axis and Y-axis are parallel to the horizontal direction, and the Z-axis is parallel to the vertical direction. In addition, in this specification, a planar view typically refers to viewing an object from the vertical direction.

[0024] A dielectrophoresis device 1 according to an embodiment of the present invention will be described with reference to Figures 1 to 6. Figure 1 is a plan view showing the dielectrophoresis device 1.

[0025] As shown in FIG. 1, a dielectrophoresis device 1 applies a dielectrophoretic force to dielectric particles P1 contained in a first fluid, thereby separating the dielectric particles P1 from other particles P2 and collecting the dielectric particles P1. The first fluid is, for example, a liquid. The first fluid is a fluid containing the dielectric particles P1 and other particles P2. Typically, the first fluid is a buffer solution containing the dielectric particles P1 and other particles P2. The dielectric particles P1 are, for example, microorganisms, cells, proteins, or nucleic acids. The microorganisms are, for example, fungi (e.g., bacteria or fungi) or viruses. The other particles P2 are, for example, particles of a different type from the dielectric particles P1, or particles of the same type as the dielectric particles P1 but in a different state. Particles in a different state are, for example, living particles (e.g., cells) and dead particles (e.g., cells).

[0026] Specifically, the dielectrophoresis device 1 includes a fluid chip 11. The fluid chip 11 applies a dielectrophoretic force to the dielectric particles P1 contained in the first fluid, thereby separating the dielectric particles P1 from other particles P2 and collecting the dielectric particles P1. The diameter of the dielectric particles P1 is, for example, several μm or more and several tens of μm or less.

[0027] The fluid chip 11 includes a substrate 21, a flow channel 31, a pair of second electrodes 33a, 33b, a pair of first electrodes 43a, 43b, a pair of second electrode pad portions 331a, 331b, and a pair of first electrode pad portions 431a, 431b.

[0028] The material of the substrate 21 is, for example, glass or silicon. However, the material of the substrate 21 is not limited to quartz glass. The substrate 21 has a substantially rectangular flat plate shape. However, the shape of the substrate 21 is not limited to a substantially rectangular flat plate shape.

[0029] The flow channel 31 is disposed on one main surface 211 of a pair of main surfaces of the substrate 21. In the example of FIG. 1, the one main surface 211 of the substrate 21 is the upper surface of the substrate 21, and the other main surface of the substrate 21 is the lower surface of the substrate 21.

[0030] A first fluid or a second fluid can be injected into the flow path 31. The second fluid is the same type of fluid as the first fluid excluding the dielectric particles P1 and other particles P2. The second fluid is, for example, a liquid. The second fluid is typically a buffer solution. For example, the electrical resistivity of the second fluid is approximately equal to the electrical resistivity of the first fluid.

[0031] The first fluid or the second fluid flows through a channel 31. The channel 31 includes a separation channel 311 and a pair of collection channels 313a and 313b. The fluid chip 11 further includes a supply unit 315, a first collection unit 317a, and a second collection unit 317b.

[0032] The separation channel 311 extends linearly along direction D1. The width of the separation channel 311 in direction D2 is, for example, on the microscale. The direction D2 runs along the substrate 21 and is approximately perpendicular to direction D1. One end of the separation channel 311 is connected to a supply unit 315. The supply unit 315 supplies a first fluid or a second fluid to the separation channel 311. The supply unit 315 has, for example, an opening. The supply unit 315 is connected, for example, via a tube, to a fluid injection unit 100, which is a supply source of the first fluid or the second fluid. That is, the dielectrophoresis device 1 further includes the fluid injection unit 100. The fluid injection unit 100 injects the first fluid or the second fluid into the fluid chip 11. Specifically, the fluid injection unit 100 injects the first fluid or the second fluid into the supply unit 315. The fluid injection unit 100 is, for example, a syringe pump. The syringe pump includes, for example, a motor, a syringe, and a plunger.

[0033] Furthermore, the channel 31 branches at the other end of the separation channel 311 into a collection channel 313a and a collection channel 313b.

[0034] The collection channel 313a is a channel into which the dielectric particles P1 flow from the separation channel 311. The collection channel 313b is a channel into which the other particles P2 flow from the separation channel 311. One end of the collection channel 313a and one end of the collection channel 313b are connected to the other end of the separation channel 311. The other end of the collection channel 313a is connected to a first collection unit 317a. The other end of the collection channel 313b is connected to a second collection unit 317b. The first collection unit 317a collects the dielectric particles P1 to be separated. The first collection unit 317a may have, for example, an opening and supply a solution containing the dielectric particles P1 from the fluidic chip 11 to the outside. The second collection unit 317b collects the other particles P2 not to be separated. The second collection unit 317b may have, for example, an opening and supply a solution containing the other particles P2 from the fluidic chip 11 to the outside.

[0035] When a control voltage Vcn is applied to the second electrodes 33a and 33b, a dielectrophoretic force can be exerted on the dielectric particles P1 contained in the first fluid injected into the flow path 31. The control voltage Vcn is an AC voltage. The second electrodes 33a and 33b are made of a metal such as aluminum.

[0036] In a plan view, the second electrodes 33a and 33b intersect with the channel 31 (separation channel 311) at an acute angle θ. Each of the second electrodes 33a and 33b is a comb-shaped electrode. The second electrodes 33a and 33b are electrically isolated from each other.

[0037] The second electrode 33a includes a plurality of second line electrodes 333a arranged in a comb-like pattern. The plurality of second line electrodes 333a are arranged at equal intervals in direction D1. Direction D1 indicates the direction in which the flow channel 31 (separation flow channel 311) extends. The plurality of second line electrodes 333a intersect with the flow channel 31 (separation flow channel 311) at an acute angle θ in a plan view. The second line electrodes 333a cross the flow channel 31 (separation flow channel 311) at an acute angle θ. The second line electrodes 333a are connected to the second electrode pad portion 331a.

[0038] The second electrode 33b includes a plurality of second line electrodes 333b arranged in a comb-like shape. The plurality of second line electrodes 333b are arranged at equal intervals in direction D1. In a plan view, the plurality of second line electrodes 333b intersect with the flow channel 31 (separation flow channel 311) at an acute angle θ. The second line electrodes 333b cross the flow channel 31 (separation flow channel 311) at an acute angle θ. The second line electrodes 333b are connected to the second electrode pad portion 331b.

[0039] The second line electrodes 333a and the second line electrodes 333b are alternately arranged at intervals in the direction D1.

[0040] Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1. As shown in Fig. 2, the second electrodes 33a and 33b are disposed between the main surface 211 of the substrate 21 and the flow channel 31 (separation flow channel 311). Specifically, the second line electrodes 333a and 333b are disposed between the main surface 211 of the substrate 21 and the flow channel 31 (separation flow channel 311).

[0041] The fluid chip 11 further includes an insulating protective film 23 and a channel cover 25. The insulating protective film 23 covers the second electrodes 33a, 33b. The insulating protective film 23 is, for example, an oxide film or a nitride film. The oxide film is, for example, a silicon oxide film (SiOx). The nitride film is, for example, a silicon nitride film. Covering the second electrodes 33a, 33b with the insulating protective film 23 suppresses electrochemical reactions that occur at the interface between the electrode metal and the liquid, and can suppress deterioration and wear of the electrode metal over time.

[0042] The material of the channel cover 25 is, for example, silicone such as PDMS (dimethylpolysiloxane). The channel cover 25 and the upper surface of the insulating protective film 23 form a channel 31.

[0043] 1, the width of the substrate 21 in the direction D2 is greater than the width of the flow path cover 25 in the direction D2. At least a part of the second electrode pad portion 331a and at least a part of the second electrode pad portion 331b are disposed outside the flow path cover 25. Furthermore, the portions of the second electrode pad portions 331a and 331b that are disposed outside the flow path cover 25 are not covered with the insulating protective film 23.

[0044] The second electrode pad portion 331a is connected to the second electrode 33a, and the second electrode pad portion 331b is connected to the second electrode 33b.

[0045] A measurement voltage Vm is applied to the first electrodes 43a and 43b, thereby measuring the impedance IM1 between the first electrodes 43a and 43b. The measurement voltage Vm is an AC voltage. The first electrodes 43a and 43b are made of a metal such as aluminum.

[0046] The first electrodes 43a and 43b are substantially perpendicular to the channel 31 (separation channel 311) in a plan view. Each of the first electrodes 43a and 43b is a comb-shaped electrode. The first electrodes 43a and 43b are electrically isolated from each other.

[0047] The first electrodes 43a and 43b are spaced apart from the second electrodes 33a and 33b in the direction D1. Specifically, the first electrodes 43a and 43b are disposed downstream of the second electrodes 33a and 33b.

[0048] The first electrode 43a has a plurality of first line electrodes 433a arranged in a comb-like shape. The first electrode 43b has a plurality of first line electrodes 433b arranged in a comb-like shape. The plurality of first line electrodes 433a and the plurality of first line electrodes 433b extend along direction D2. The first line electrodes 433a and the first line electrodes 433b are alternately arranged at intervals in direction D1.

[0049] Some of the first line electrodes 433a are arranged at equal intervals in the direction D1, substantially perpendicular to the collection channel 313a in plan view. Some of the first line electrodes 433b are arranged at equal intervals in the direction D1, substantially perpendicular to the collection channel 313a in plan view.

[0050] Another part of the first line electrodes 433a are arranged at equal intervals in the direction D1, substantially perpendicular to the collection channel 313b in plan view. Another part of the first line electrodes 433b are arranged at equal intervals in the direction D1, substantially perpendicular to the collection channel 313b in plan view.

[0051] The first line electrode 433a is connected to the first electrode pad portion 431a. The first line electrode 433a crosses the flow path 31 (collection flow path 313a) at a substantially right angle. The first line electrode 433b is connected to the first electrode pad portion 431b. The first line electrode 433b crosses the flow path 31 (collection flow path 313b) at a substantially right angle.

[0052] Fig. 3 is a schematic cross-sectional view taken along line III-III in Fig. 1. Fig. 3 shows first electrodes 43a and 43b on the side of collection channel 313a. As shown in Fig. 3, first electrodes 43a and 43b are disposed between main surface 211 of substrate 21 and channel 31 (collection channel 313a). Specifically, first line electrodes 433a and 433b are disposed between main surface 211 of substrate 21 and channel 31 (collection channel 313a).

[0053] The insulating protective film 23 covers the first electrodes 43a and 43b. The channel cover 25 and the upper surface of the insulating protective film 23 form the channel 31 (collection channel 313a).

[0054] The first line electrodes 433a and 433b on the collection channel 313b side are configured in the same manner as the first line electrodes 433a and 433b on the collection channel 313a side.

[0055] Returning to FIG. 1, at least a portion of the first electrode pad portion 431a and at least a portion of the first electrode pad portion 431b are disposed outside the flow path cover 25. Furthermore, of the first electrode pad portions 431a and 431b, the portions disposed outside the flow path cover 25 are not covered with the insulating protective film 23. The first electrode pad portion 431a is connected to the first electrode 43a. The first electrode pad portion 431b is connected to the first electrode 43b.

[0056] The dielectrophoresis device 1 further includes a control device 200. The control device 200 controls the fluid chip 11 and the fluid injection unit 100.

[0057] Specifically, the control device 200 includes a first power supply unit 201, a second power supply unit 202, a measurement unit 203, a control unit 204, and a storage unit 205.

[0058] The second power supply unit 202 is electrically connected to the second electrode pad units 331a and 331b. The second power supply unit 202 applies a control voltage Vcn corresponding to the dielectric particles P1 to the second electrodes 33a and 33b via the second electrode pad units 331a and 331b. That is, the second power supply unit 202 applies the control voltage Vcn corresponding to the dielectric particles P1 between the second electrodes 33a and 33b via the second electrode pad units 331a and 331b. The control voltage Vcn is an AC voltage. The second power supply unit 202 is, for example, a signal generator such as a function generator.

[0059] The control voltage Vcn according to the dielectric particles P1 is a frequency that generates an electric field that specifically exerts a dielectrophoretic force (attractive force) on the dielectric particles P1, and is a voltage of a magnitude that does not destroy the dielectric particles P1.

[0060] Specifically, the frequency of the control voltage Vcn is set so that a positive dielectrophoretic force (attractive force) acts on the dielectric particles P1 by the second electrodes 33a, 33b. Therefore, a positive dielectrophoretic force (attractive force) acts on the dielectric particles P1, and the dielectric particles P1 flow through the separation channel 311 along the extension direction of the second electrodes 33a, 33b (second line electrodes 333a, 333b) while being attracted to the second electrodes 33a, 33b (second line electrodes 333a, 333b), and are collected in the first collector 317a through the collection channel 313a. On the other hand, the frequency of the control voltage Vcn is set so that no dielectrophoretic force acts on the other particles P2, or even if a positive or negative dielectrophoretic force (attractive force or repulsive force) acts on the other particles P2, the dielectrophoretic force is relatively small. Therefore, the other particles P2 are carried by the flow in direction D1 in separation channel 311, pass through collection channel 313b and are collected in second collection section 317b.

[0061] 1 to 3, a control voltage Vcn that applies a dielectrophoretic force to the dielectric particles P1 contained in the first fluid is applied to the fluid chip 11. Then, by applying a positive dielectrophoretic force (attractive force) to the dielectric particles P1, the fluid chip 11 separates the dielectric particles P1 from other particles P2 and collects the dielectric particles P1 in the first collector 317a.

[0062] The first power supply unit 201 generates a measurement voltage Vm. The first power supply unit 201 applies the measurement voltage Vm to the first electrodes 43a and 43b via the first electrode pad units 431a and 431b. The first power supply unit 201 is, for example, a signal generator such as a function generator.

[0063] The measuring unit 203 measures the impedance IM1 between the first electrodes 43a and 43b via the second fluid. In this case, the measuring unit 203 measures the impedance IM1 for each frequency while changing the frequency of the measurement voltage Vm.

[0064] With the first power supply unit 201 applying a measurement voltage Vm between the first electrodes 43a and 43b, the measurement unit 203 measures the impedance I M1 between the pair of first electrodes 43a and 43b via the second fluid injected into the flow path 31. Specifically, with the first power supply unit 201 applying the measurement voltage Vm between the first electrodes 43a and 43b, the measurement unit 203 measures the current flowing between the first electrodes 43a and 43b via the first electrodes 43a and 43b. The measurement unit 203 calculates the impedance I M1 between the first electrodes 43a and 43b from the measurement voltage Vm and the current measured via the first electrodes 43a and 43b. The measurement unit 203 is, for example, a measuring instrument such as an oscilloscope.

[0065] The measurement unit 203 outputs to the control unit 204 data indicating the frequency of the measurement voltage Vm and the impedance IM1 between the first electrodes 43a and 43b.

[0066] The control unit 204 controls the first power supply unit 201, the second power supply unit 202, the measurement unit 203, the storage unit 205, and the fluid injection unit 100. The control unit 204 includes, for example, a processor. The processor is, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit).

[0067] The storage unit 205 stores data and computer programs. The storage unit 205 is, for example, a storage device. The storage device includes a main storage device such as a semiconductor memory and an auxiliary storage device such as a semiconductor memory, a solid-state drive, and / or a hard disk drive. The storage device may also include removable media. The storage device is an example of a non-transitory computer-readable storage medium.

[0068] The control device 200 may be constituted by, for example, a source-measure unit.

[0069] Next, a control voltage correction method according to this embodiment will be described with reference to Figures 1 to 6. The control voltage correction method corrects a control voltage Vcn that applies a dielectrophoretic force to dielectric particles P1 contained in a first fluid injected into the fluid chip 11. In this embodiment, by performing the control voltage correction method, it is possible to reduce the influence of parasitic components of the fluid chip 11 on the separation and collection performance of the dielectric particles P1 from other particles P2 in the fluid chip 11.

[0070] Before describing specific corrections, the parasitic components of the fluid chip 11 will be described first. The parasitic components of the fluid chip 11 include device parasitic components caused by the fluid chip 11 itself and fluid parasitic components. The device parasitic components include the parasitic resistance of the electrode metal, the parasitic resistance and parasitic capacitance of the insulating protective film 23, and the parasitic resistance and parasitic capacitance of the interface between the electrode metal and the fluid. The fluid parasitic components are the parasitic resistance and parasitic capacitance of the fluid. The electrode metal refers to the first electrodes 43a, 43b or the second electrodes 33a, 33b. The fluid refers to the first fluid or the second fluid.

[0071] The control voltage Vcn applied to the first fluid is attenuated by device parasitic components, and the amount of attenuation is frequency-dependent due to the presence of parasitic capacitance (electrostatic capacitance component). Therefore, when the control voltage Vcn having a specific voltage value Vx is applied to the second electrodes 33a and 33b, the voltage value of the voltage actually applied to the first fluid differs from the specific voltage value Vx, which is the target value of the voltage to be applied to the first fluid.

[0072] Therefore, the voltage value of the control voltage Vcn is corrected by adding the voltage value attenuated by the device parasitic component to the specific voltage value Vx. Specifically, as shown in equation (1), the correction voltage value Vy is calculated by multiplying the specific voltage value Vx by a correction coefficient C. The correction coefficient C is a real number greater than 1. By applying the control voltage Vcn having the correction voltage value Vy to the first fluid, the voltage value of the voltage actually applied to the first fluid becomes the specific voltage value Vx, which is the target value.

[0073] Vy = C × Vx …(1)

[0074] The control voltage correction method will be described in detail below. Fig. 4 is a block diagram showing the control unit 204. As shown in Fig. 4, the control unit 204 includes a correction coefficient calculation unit 251 and a voltage control unit 252. Specifically, the processor of the control unit 204 executes a computer program stored in the storage device of the storage unit 205, thereby functioning as the correction coefficient calculation unit 251 and the voltage control unit 252.

[0075] 5 is a flowchart showing the control voltage correction method according to this embodiment. As shown in FIG. 5, the control voltage correction method includes steps S1 to S6.

[0076] 1 and 5, first, in step S1, the fluid injection unit 100 injects the second fluid into the fluidic chip 11. Specifically, the fluid injection unit 100 injects the second fluid into the supply unit 315, thereby injecting the second fluid into the flow path 31 via the supply unit 315.

[0077] Next, in step S2, the first power supply unit 201 applies a measurement voltage Vm between the pair of first electrodes 43a, 43b, and the measurement unit 203 measures the impedance IM1 between the pair of first electrodes 43a, 43b via the second fluid injected into the flow path 31. The measurement voltage Vm has a specific voltage value Vx. The measurement voltage Vm is an AC voltage. Therefore, the specific voltage value Vx is represented by an effective value.

[0078] Preferably, the measurement unit 203 measures the impedance I M1 between the pair of first electrodes 43 a, 43 b via the second fluid for each frequency while changing the frequency of the measurement voltage Vm. Then, the storage unit 205 stores the impedance I M1 between the pair of first electrodes 43 a, 43 b for each frequency of the measurement voltage Vm.

[0079] 4 and 5, in step S3, the correction coefficient calculation unit 251 calculates a correction coefficient C based on the impedance IM1 between the pair of first electrodes 43a, 43b measured in step S2 and the fluid impedance IM2 derived by a formula. The fluid impedance IM2 is the impedance of the first fluid or the impedance of the second fluid. The impedance of the first fluid and the impedance of the second fluid are approximately equal.

[0080] Preferably, the correction coefficient calculation unit 251 calculates the correction coefficient C for each frequency of the measurement voltage Vm based on the impedance IM1 between the pair of first electrodes 43a, 43b and the fluid impedance IM2 derived by a mathematical formula.

[0081] FIG. 6 is a graph showing the correction coefficient C. For ease of understanding, FIG. 6 shows the correction coefficient C as a percentage [%]. The horizontal axis represents the frequency [MHz] of the measurement voltage Vm, and the vertical axis represents the correction coefficient C [%]. As shown in FIG. 6, the correction coefficient calculation unit 251 calculates the correction coefficient C for each frequency.

[0082] The correction coefficient C is expressed by equation (2) using the voltage output efficiency VOE. The voltage output efficiency VOE is expressed by equation (3). Therefore, the voltage output efficiency VOE indicates the ratio of the "voltage value of the voltage actually applied to the second fluid when a measurement voltage Vm having a specific voltage value Vx is applied to the first electrodes 43a, 43b" to the "specific voltage value Vx, which is the target value of the voltage to be applied to the second fluid." In other words, the voltage output efficiency VOE indicates the ratio of the "voltage value of the voltage actually applied to the first fluid when a control voltage Vcn having a specific voltage value Vx is applied to the second electrodes 33a, 33b" to the "specific voltage value Vx, which is the target value of the voltage to be applied to the first fluid." This is because the electrical resistivity of the first fluid and the electrical resistivity of the second fluid are approximately equal.

[0083] C=1 / VOE …(2) VOE=IM2 / IM1 …(3)

[0084] Returning to FIG. 5, next, in step S4, the voltage control unit 252 corrects the control voltage Vcn applied between the pair of second electrodes 33a, 33b based on the correction coefficient C. Specifically, the voltage control unit 252 corrects the control voltage Vcn having the specific voltage value Vx based on the correction coefficient C. That is, the voltage control unit 252 corrects the specific voltage value Vx based on the correction coefficient C to calculate the corrected voltage value Vy. Specifically, the voltage control unit 252 calculates the corrected voltage value Vy using the above equation (1). In this case, the voltage control unit 252 selects, from the frequency-dependent correction coefficients C (FIG. 6), a correction coefficient C that corresponds to a frequency fx (hereinafter referred to as a "specific frequency fx") that is set in advance for the control voltage Vcn.

[0085] Next, in step S5, the fluid injection unit 100 injects the first fluid into the fluidic chip 11. Specifically, the fluid injection unit 100 injects the first fluid into the supply unit 315, thereby injecting the first fluid into the flow path 31 via the supply unit 315.

[0086] Next, in step S6, the voltage control unit 252 controls the second power supply unit 202 to output the corrected control voltage Vcn. As a result, the second power supply unit 202 applies the corrected control voltage Vcn between the second electrodes 33a and 33b. Specifically, the second power supply unit 202 applies the control voltage Vcn having the corrected voltage value Vy and the specific frequency fx between the second electrodes 33a and 33b.

[0087] As described above with reference to Figure 5, according to this embodiment, by correcting the control voltage Vcn using the correction coefficient C, the influence of device parasitic components on the separation and collection performance of the dielectric particles P1 from other particles P2 contained in the first fluid can be reduced.

[0088] In particular, when calculating the correction coefficient C, the correction coefficient calculation unit 251 uses the fluid impedance IM2 derived by a formula, rather than an actual measurement value. Therefore, it is not necessary to provide a test electrode and a test flow path for calculating the correction coefficient C. Therefore, it is possible to prevent the size of the fluid chip 11 from increasing.

[0089] Therefore, according to this embodiment, the control voltage Vcn can be corrected while preventing the size of the fluid chip 11 from increasing.

[0090] In this embodiment, the impedance IM1 between the first electrodes 43a and 43b is measured via the second fluid (step S2). In this case, the second fluid is the same fluid as the first fluid minus the dielectric particles P1 and other particles P2. Therefore, it is only necessary to prepare the second fluid, which is the fluid before the dielectric particles P1 and other particles P2 are mixed in. As a result, it is not necessary to separately prepare a test liquid with different electrical properties. This reduces the cost of calculating the correction coefficient C. Furthermore, it is possible to prevent new surface contamination due to the test fluid with different electrical properties and clogging of the flow path due to the inclusion of particles.

[0091] In the reference example, the test liquid is a sodium chloride solution or the like, which has a lower electrical resistivity than the first fluid. In other words, a liquid with high electrical conductivity must be separately prepared as the test liquid. The test liquid is then injected into the test flow path, and the impedance IMa is measured using the test electrode via the test liquid. Meanwhile, the sample liquid is injected into the main flow path, and the impedance IMa is measured using the main electrode via the sample liquid. Then, the voltage output efficiency VOEx (=(IMb-IMa) / IMb) is calculated. Furthermore, the correction coefficient Cx (=1 / VOEx) is calculated.

[0092] Furthermore, this embodiment does not require the preparation of a test liquid with high electrical conductivity, the injection of the test liquid into the test flow path, or the measurement of the impedance IMa using a test electrode via the test liquid, thereby reducing the cost, labor, and environmental impact required to calculate the correction coefficient C.

[0093] Furthermore, in this embodiment, the fluid injection unit 100 injects a second fluid for measuring the impedance IM1 into the flow path 31 of the fluid chip 11, and then injects a first fluid containing the dielectric particles P1 into the flow path 31 of the fluid chip 11 (step S5). That is, before injecting the first fluid containing the dielectric particles P1 to be captured, a preliminary operation is performed to fill the flow path 31 with a second fluid, which is the same as the first fluid except that the dielectric particles P1 and other particles P2 have been removed from the first fluid. Then, after the second fluid has been filled and before the first fluid is injected, or while the second fluid is being filled, the impedance IM1 is measured. Therefore, the operation for calculating the correction coefficient C can be performed during the preliminary operation performed before the main operation for capturing the dielectric particles P1. As a result, in this embodiment, a seamless process from the operation for calculating the correction coefficient C to the main operation for capturing the dielectric particles P1 is possible, compared to the reference example, which requires a dedicated operation time and a separate testing electrode, etc., for calculating the correction coefficient Cx. Therefore, it is possible to substantially eliminate the time difference between the correction of the control voltage Vcn and the capture of the dielectric particles P1 by the application of the control voltage Vcn, thereby improving the accuracy of the correction.

[0094] Furthermore, in this embodiment, the pair of first electrodes 43a, 43b used to measure the impedance IM1 are positioned downstream in the flow of the first or second fluid from the pair of second electrodes 33a, 33b to which the control voltage Vcn for capturing the dielectric particles P1 is applied. Therefore, according to this embodiment, the impedance IM1 can be measured even during the period when the first fluid is injected into the flow path 31 and the dielectric particles P1 are captured by the second electrodes 33a, 33b. Therefore, the correction coefficient C can be modified during the period when the dielectric particles P1 are captured. As a result, the correction voltage value Vy of the control voltage Vcn can be modified depending on the capture status of the dielectric particles P1. This further reduces the influence of device parasitics on the separation and collection performance of the dielectric particles P1 from other particles P2 contained in the first fluid.

[0095] Furthermore, in this embodiment, the mathematical formula for deriving the fluid impedance IM2 is a theoretical formula. The theoretical formula includes the electrical resistivity or electrical conductivity of the first fluid, or the theoretical formula includes the electrical resistivity or electrical conductivity of the second fluid. Therefore, the fluid impedance IM2 can be easily derived by the theoretical formula.

[0096] Equation (4) is an example of a theoretical formula. In equation (4), "ρ" represents the electrical resistivity of the first fluid or the second fluid. "σ" represents the electrical conductivity of the first fluid or the second fluid. "ρ" and "σ" are material-specific values ​​determined by the type of the first fluid or the second fluid. "L" represents the length of the first fluid or the second fluid. "S" represents the cross-sectional area of ​​the first fluid or the second fluid. Specifically, "L" and "S" are determined based on the structure and dimensions of the first electrodes 43a, 43b (first line electrodes 433a, 433b) that measure the fluid impedance IM2.

[0097] IM2=ρ×(L / S)=(1 / σ)×(L / S) …(4)

[0098] Preferably, the formula for deriving the fluid impedance IM2 is an empirical formula. The empirical formula is a function determined by the electrical characteristics of the fluid chip 11 and the dielectrophoretic characteristics of the dielectric particles P1. Therefore, the fluid impedance IM2 can be derived according to the electrical characteristics of the fluid chip 11 and the dielectrophoretic characteristics of the dielectric particles P1. As a result, the correction coefficient C can be calculated more appropriately using the fluid impedance IM2.

[0099] Equation (5) is an example of an empirical formula. The function F(IM1) is a function determined by the electrical characteristics of the fluid chip 11 and the dielectrophoretic characteristics of the dielectric particles P1. The function F(IM1) has, as a variable, the impedance IM1 between the first electrodes 43a, 43b measured by the measurement unit 203. For example, the function F(IM1) is derived based on the relationship between the electrical characteristics of the fluid chip 11 and the dielectrophoretic characteristics of the dielectric particles P1 and the resistance value of the first fluid. Note that another example of the empirical formula may be a function that does not have the impedance IM1 as a variable.

[0100] IM2=F(IM1) …(5)

[0101] Furthermore, in this embodiment, it is preferable that the correction coefficient calculation unit 251 calculates the correction coefficient C every time the frequency of the control voltage Vcn is changed. It is also preferable that the voltage control unit 252 corrects the control voltage Vcn based on the correction coefficient C calculated in response to a change in the frequency of the control voltage Vcn. According to this preferable example, it is possible to appropriately correct the control voltage Vcn in accordance with the frequency for each frequency of the control voltage Vcn.

[0102] (First Modification) A first modified example of this embodiment will be described with reference to Fig. 4 and Fig. 7 to Fig. 9. The first modified example differs from the embodiment described above with reference to Fig. 5 mainly in that the correction coefficient C is changed by feeding back the separation characteristics of the dielectric particles P1. Below, the differences between the first modified example and the embodiment described above will be mainly described.

[0103] FIG. 7 is a plan view showing a dielectrophoresis device 1A according to a first modified example of this embodiment. As shown in FIG. 7, the dielectrophoresis device 1A further includes an imaging unit 300 in addition to the configuration of the dielectrophoresis device 1 in FIG. 1. The imaging unit 300 is, for example, a camera. The camera includes, for example, an image sensor. The imaging unit 300 captures an image of the dielectric particles P1 in a region of interest 301. The region of interest 301 is a region downstream of the pair of second electrodes 33a, 33b in the flow of the first fluid or the second fluid. The region of interest 301 is a region upstream of the pair of first electrodes 43a, 43b in the flow of the first fluid or the second fluid. Specifically, the region of interest 301 includes a region where the separation channel 311 branches into a collection channel 313a and a collection channel 313b. That is, the region of interest 301 includes the downstream end of the separation channel 311, the upstream end of the collection channel 313a, and the upstream end of the collection channel 313b. In the example of Fig. 7, the region of interest 301 includes the upstream end of the collection channel 313a and the upstream end of the collection channel 313b, but the downstream end of the separation channel 311 is its main region.

[0104] The region of interest 301 corresponds to an example of the "region" of the present invention.

[0105] Fig. 8 is a flowchart showing a control voltage correction method according to Modification 1. As shown in Fig. 8, the control voltage correction method includes steps S21 to S31.

[0106] 8, steps S21 to S26 are executed. Steps S21 to S26 are similar to steps S1 to S6 in FIG.

[0107] Next, as shown in FIGS. 7 and 8, in step S27, the imaging section 300 captures an image of the dielectric particle P1 in the region of interest 301.

[0108] 4 and 8, in step S28, the correction coefficient calculation unit 251 changes the correction coefficient C based on the imaging results of the dielectric particles P1. Therefore, according to the first modification, the correction coefficient calculation unit 251 can calculate the correction coefficient C in which the separation status of the dielectric particles P1 by the second electrodes 33a, 33b is fed back. As a result, the separation performance and collection performance of the dielectric particles P1 from other particles P2 in the fluid chip 11 can be further improved.

[0109] Specifically, step S28 includes step S281 and step S282.

[0110] In step S281, when the control voltage Vcn is applied to the pair of second electrodes 33a, 33b to separate the dielectric particles P1 from the other particles P2, the correction coefficient calculation unit 251 calculates the frequency dependence of the separation rate SP of the dielectric particles P1 based on the imaging results of the dielectric particles P1. The separation rate SP of the dielectric particles P1 is the ratio of the number K of the dielectric particles P1 that flow into the collection flow path 313a per certain time to the number M of the dielectric particles P1 that reach the region of interest 301 per certain time. In other words, SP = K / M.

[0111] Specifically, the imaging unit 300 images the dielectric particles P1 in the region of interest 301 while the second power supply unit 202 changes the frequency of the control voltage Vcn. As a result, captured images showing the imaging results of the dielectric particles P1 are obtained for each frequency. The correction coefficient calculation unit 251 then analyzes the captured images of the dielectric particles P1 obtained for each frequency and calculates the separation rate SP for each frequency. As a result, information showing the frequency dependency of the separation rate SP of the dielectric particles P1 is obtained.

[0112] Next, in step S282, the correction coefficient calculation section 251 changes the correction coefficient C based on the frequency dependency of the separation rate SP of the dielectric particles P1.

[0113] FIG. 9 is a graph showing the frequency dependence of the separation ratio SP of the dielectric particles P1. The horizontal axis represents the frequency of the control voltage Vcn. The vertical axis represents the separation ratio SP. As shown in FIG. 9, the correction coefficient calculation unit 251 calculates information 401, 402, and 403 indicating the frequency dependence of the separation ratio SP based on the image captured by the imaging unit 300, and repeatedly changes the correction coefficient C until the target separation ratio SP1 is obtained at a specific frequency fx, which is the target frequency. In the example of FIG. 9, the frequency dependence of the separation ratio SP indicated by information 401 achieves the target separation ratio SP1 at the specific frequency fx. On the other hand, the frequency dependence of the separation ratio SP indicated by information 402 and information 403 does not achieve the target separation ratio SP1 at the specific frequency fx. Therefore, the correction coefficient C is repeatedly changed until the frequency dependence of the separation ratio SP indicated by information 401 is obtained. Note that in the example of FIG. 9, the target separation ratio SP1 is 0.5 (50%), but is not limited to this.

[0114] Next, in step S29, the voltage control unit 252 changes the control voltage Vcn based on the correction coefficient C after the change.

[0115] Next, in step S30, the voltage control unit 252 controls the second power supply unit 202 to output the changed control voltage Vcn. As a result, the second power supply unit 202 applies the changed control voltage Vcn between the second electrodes 33 a and 33 b. Specifically, the second power supply unit 202 applies the control voltage Vcn having the changed correction voltage value Vy and the specific frequency fx between the second electrodes 33 a and 33 b.

[0116] Next, in step S31, the correction coefficient calculation unit 251 determines whether a change completion condition for the correction coefficient C is satisfied. The change completion condition is that the frequency dependency of the separation rate SP of the dielectric particles P1 satisfies a predetermined condition. The predetermined condition is that the target separation rate SP1 is obtained at a specific frequency fx that is the target frequency in the information indicating the frequency dependency of the separation rate SP.

[0117] If it is determined in step S31 that the change completion condition is not satisfied (No), the process proceeds to step S27. Therefore, imaging and change of the correction coefficient C are executed until the change completion condition is satisfied.

[0118] On the other hand, if it is determined in step S31 that the change completion condition is met (Yes), the voltage correction method ends.

[0119] (Second Modification) A second modified example of this embodiment will be described with reference to Figures 4, 7, and 10. The second modified example differs from the first modified example described above with reference to Figure 8 mainly in that the correction coefficient C is calculated based on the impedance IM1 and fluid impedance IM2 measured between the pair of first electrodes 43a, 43b via the first fluid. Below, the differences between the second modified example and the first modified example will be mainly described.

[0120] Fig. 10 is a flowchart showing a control voltage correction method according to Modification 2. As shown in Fig. 10, the control voltage correction method includes steps S41 to S50.

[0121] 7 and 10 , first, in step S41, the fluid injection unit 100 injects a first fluid into the fluidic chip 11. Specifically, the fluid injection unit 100 injects the first fluid into the supply unit 315, thereby injecting the first fluid into the flow path 31 via the supply unit 315.

[0122] Next, in step S42, the first power supply unit 201 applies a measurement voltage Vm between the pair of first electrodes 43a, 43b, and the measurement unit 203 measures the impedance IM1 between the pair of first electrodes 43a, 43b via the first fluid injected into the flow path 31. The measurement voltage Vm has a specific voltage value Vx. The measurement voltage Vm is an AC voltage. Therefore, the specific voltage value Vx is represented by an effective value.

[0123] Preferably, the measurement unit 203 measures the impedance I M1 between the pair of first electrodes 43 a, 43 b via the first fluid for each frequency while changing the frequency of the measurement voltage Vm. Then, the storage unit 205 stores the impedance I M1 between the pair of first electrodes 43 a, 43 b for each frequency of the measurement voltage Vm.

[0124] 4 and 10, in step S43, the correction coefficient calculation unit 251 calculates a correction coefficient C based on the impedance IM1 between the pair of first electrodes 43a, 43b measured in step S42 and the fluid impedance IM2 derived by a mathematical formula. Step S43 is similar to step S23 in FIG. 8.

[0125] Next, in step S44, the voltage control unit 252 corrects the control voltage Vcn to be applied between the pair of second electrodes 33a, 33b based on the correction coefficient C. Step S44 is similar to step S24 in FIG.

[0126] Next, in step S45, the voltage control unit 252 controls the second power supply unit 202 to output the corrected control voltage Vcn. As a result, the second power supply unit 202 applies the corrected control voltage Vcn between the second electrodes 33a and 33b. Step S45 is the same as step S26 in FIG. 8.

[0127] Next, steps S46 to S50 are executed. Steps S46 to S50 are respectively similar to steps S27 to S31 in Fig. 8. Furthermore, steps S471 and S472 in Fig. 10 are respectively similar to steps S281 and S282 in Fig. 8.

[0128] The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiments and can be implemented in various forms without departing from the spirit of the present invention. Furthermore, the components disclosed in the above embodiments can be modified as appropriate. For example, some of the components shown in one embodiment may be added to the components of another embodiment, or some of the components shown in one embodiment may be deleted from the embodiment.

[0129] Furthermore, the drawings mainly show each component in a schematic manner to facilitate understanding of the invention, and the thickness, length, number, spacing, etc. of each component shown in the drawings may differ from the actual ones due to the convenience of creating the drawings. Furthermore, the configuration of each component shown in the above embodiment is merely an example and is not particularly limited, and it goes without saying that various modifications are possible within a range that does not substantially deviate from the effects of the present invention.

[0130] (1) In the embodiment described with reference to Fig. 5, the measurement unit 203 measured the impedance I M1 between the first electrodes 43a and 43b via the second fluid. However, the measurement unit 203 may measure the impedance I M1 between the first electrodes 43a and 43b via the first fluid. The correction coefficient calculation unit 251 may then calculate the correction coefficient C based on the impedance I M1 measured via the first fluid and the fluid impedance I M2 derived using a mathematical formula.

[0131] (2) In FIGS. 1 to 3, the insulating protective film 23 may not be provided. [Industrial Applicability]

[0132] The present invention relates to a control voltage correction method and a dielectrophoresis device, and has industrial applicability. [Explanation of symbols]

[0133] 1. Dielectrophoresis device 11 Fluidic Chip 33a, 33b 2nd electrode 43a, 43b 1st electrode 100 Fluid injection part 203 Measuring section 251 Correction coefficient calculation unit 252 Voltage control section 300 Imaging unit P1 dielectric particles P2 Other particles

Claims

1. 1. A control voltage correction method for correcting a control voltage that applies a dielectrophoretic force to dielectric particles contained in a first fluid injected into a fluid chip, comprising: measuring an impedance between a pair of first electrodes in the fluidic chip via the first fluid or the second fluid; calculating a correction coefficient based on the measured impedance between the pair of first electrodes and the fluid impedance derived by a mathematical formula; correcting the control voltage based on the correction coefficient; Including, the fluid impedance indicates the impedance of the first fluid or the impedance of the second fluid, the first fluid is a fluid containing the dielectric particles and other particles, A control voltage correction method, wherein the second fluid is the same type of fluid as the first fluid excluding the dielectric particles and the other particles.

2. The control voltage correction method according to claim 1 , wherein the pair of first electrodes is arranged downstream in a flow of the first fluid or the second fluid from a pair of second electrodes to which the control voltage is applied.

3. capturing an image of the dielectric particles in a region downstream of the pair of second electrodes and upstream of the pair of first electrodes; changing the correction coefficient based on the imaging result of the dielectric particles; Including, The control voltage correction method according to claim 2 , wherein in the correcting step, the control voltage is corrected based on the correction coefficient after the correction coefficient has been changed.

4. The step of modifying comprises: determining frequency dependence of a separation rate of the dielectric particles based on an imaging result of the dielectric particles when the dielectric particles are separated from the other particles by applying the control voltage to the pair of second electrodes; changing the correction coefficient based on the frequency dependency of the separation rate of the dielectric particles; The control voltage correction method of claim 3 , comprising:

5. injecting the second fluid into a channel of the fluidic chip; injecting the second fluid into the flow channel of the fluidic chip, and then injecting the first fluid into the flow channel of the fluidic chip; Further comprising: In the measuring step, an impedance between the pair of first electrodes is measured via the second fluid; 3. The control voltage correction method according to claim 1, wherein in the calculating step, the correction coefficient is calculated based on the impedance between the pair of first electrodes measured via the second fluid and the fluid impedance derived by the formula.

6. The formula is a theoretical formula or an empirical formula, the theoretical formula includes an electrical resistivity or an electrical conductivity of the first fluid or an electrical resistivity or an electrical conductivity of the second fluid, 3. The control voltage correction method according to claim 1, wherein the empirical formula is a function determined by electrical characteristics of the fluid chip and dielectrophoretic characteristics of the dielectric particles.

7. The correction coefficient is calculated every time the frequency of the control voltage is changed, 3. The control voltage correction method according to claim 1, wherein the control voltage is corrected based on the correction coefficient calculated in response to a change in the frequency of the control voltage.

8. a fluidic chip including a pair of first electrodes to which a control voltage is applied to cause a dielectrophoretic force to act on dielectric particles contained in the first fluid; a measuring unit that measures the impedance between the pair of first electrodes via the first fluid or the second fluid; a correction coefficient calculation unit that calculates a correction coefficient based on the measured impedance between the pair of first electrodes and the fluid impedance derived by a mathematical formula; a voltage control unit that corrects the control voltage based on the correction coefficient; Equipped with the fluid impedance indicates the impedance of the first fluid or the impedance of the second fluid, the first fluid is a fluid containing the dielectric particles and other particles, A dielectrophoretic device, wherein the second fluid is the same type of fluid as the first fluid excluding the dielectric particles and the other particles.

9. the fluidic chip further includes a pair of second electrodes to which the control voltage is applied; The dielectrophoresis device according to claim 8 , wherein the pair of first electrodes are arranged downstream of the pair of second electrodes in a flow of the first fluid or the second fluid.

10. an imaging unit configured to image the dielectric particles in a region downstream of the pair of second electrodes and upstream of the pair of first electrodes in the flow direction, the correction coefficient calculation unit changes the correction coefficient based on an imaging result of the dielectric particle; The dielectrophoretic device according to claim 9 , wherein the voltage control unit corrects the control voltage based on the changed correction coefficient.

11. The dielectrophoretic device of claim 10, wherein when the dielectric particles are separated from the other particles by applying the control voltage to the pair of second electrodes, the correction coefficient calculation unit determines the frequency dependence of the separation rate of the dielectric particles based on the imaging results of the dielectric particles, and changes the correction coefficient based on the frequency dependence.

12. a fluid injection unit that injects the first fluid or the second fluid into a channel of the fluid chip; the fluid injection unit injects the second fluid into the flow channel of the fluidic chip, and then injects the first fluid into the flow channel of the fluidic chip; the measurement unit measures the impedance between the pair of first electrodes via the second fluid; 10. The dielectrophoresis device according to claim 8, wherein the correction coefficient calculation unit calculates the correction coefficient based on the impedance between the pair of first electrodes measured via the second fluid and the fluid impedance derived by the mathematical formula.

13. The formula is a theoretical formula or an empirical formula, the theoretical formula includes an electrical resistivity or an electrical conductivity of the first fluid or an electrical resistivity or an electrical conductivity of the second fluid, 10. The dielectrophoresis device according to claim 8, wherein the empirical formula is a function determined by electrical characteristics of the fluid chip and dielectrophoretic characteristics of the dielectric particles.

14. the correction coefficient calculation unit calculates the correction coefficient every time the frequency of the control voltage is changed; 10. The dielectrophoresis device according to claim 8, wherein the voltage control unit corrects the control voltage based on the correction coefficient calculated in response to a change in the frequency of the control voltage.

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