JP2010008332A - Electrokinetic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrokinetic apparatus capable of reducing the occurrence of air bubbles in an electrode while suppressing the enlargement in size and complication of the apparatus. <P>SOLUTION: A voltage feed part constituted of a power supply 43 and electric wiring parts 24 and 25 is constituted so as to apply voltage across electrodes 16 and 17 to move the fluid in a flow channel by electrokinetics. Further, catalysts for ionizing the gases respectively produced by the electrodes 16 and 17 are provided according to the respective electrodes 16 and 17. A continuity part constituted of electric wiring parts 60 and 61 allows the catalysts to have electrical continuity to each other. A control part 70 changes over the ON/OFF of the application of voltage by the voltage feed part and the ON/OFF of continuity by the continuity part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrokinetic device that moves fluid in a flow path by electrokinetics.

  2. Description of the Related Art In recent years, chemical analysis systems that handle a small amount of liquid, called a lab chip (Lab on a Chip), a micro chemical analysis system (μTAS: Micro Total Analysis System), and a bio micro chip, have been actively developed. In this chemical analysis system, elements such as a flow path, a reaction tank, a pump, a valve, and a sensor are integrated on a substrate such as glass or silicon. In addition, movement, reaction, synthesis, analysis, and the like of a liquid sample are performed inside a chip constituted by these elements.

  This chemical analysis system has the following advantages by downsizing. First, the sample can be reduced. In addition, the price of the chemical analysis system can be reduced. Such chemical analysis systems are expected to be applied in the field of clinical medicine such as home medical care and bedside monitors, and in the field of biotechnology such as DNA analysis.

  As an example of a chemical analysis system, there is a small analysis system that conducts a clinical test by flowing a sample through a fine flow path on the order of μm provided in a substrate.

  In such a small analysis system, an electrical technique has been put into practical use instead of a mechanical technique using a pump and a valve as a method of moving a minute amount of an object in a desired direction.

  Hereinafter, the movement of the object by an electrical method will be described.

  When a solid contacts a polar liquid such as water, the solid surface acquires a charge. This acquired solid surface charge affects the charge in the liquid near the solid surface.

  Specifically, the charge on the solid surface attracts ions that have a charge opposite to that on the solid surface. For this reason, ions having a charge opposite to the charge on the solid surface gather from the liquid near the solid surface on the solid surface. The ions pair with the charge on the solid surface to form an ultrathin layer called a Stern layer.

  The stern layer affects the charge distribution in the liquid and forms a diffusion layer of the same type of charge as the stern layer. The stern layer charge is fixed because it is paired with the solid surface charge, but the diffusion layer charge can move.

Here, the Stern layer and the diffusion layer form a Helmholtz electric double layer. The thickness of the diffusion layer is equal to the Debye length λ _{D of} ions. In addition, the boundary between the Stern layer and the diffusion layer is a slip surface. The potential at the boundary between the Stern layer and the diffusion layer is the zeta potential, and has the same sign as the charge forming the diffusion layer.

  The glass surface is usually covered with silanol. Silanol releases hydrogen in the liquid. For this reason, when glass contacts a polar liquid, hydrogen dissolves in the solution. Since hydrogen is negatively charged, the zeta potential is negative. In particular, quartz glass is known to increase the absolute value of the zeta potential.

  In an environment where an electric double layer is formed, an object can be moved electrically by utilizing a phenomenon called electrokinetics. As electrokinetics, electroosmotic flow, electrophoresis, dielectrophoresis and the like are known.

  Hereinafter, electroosmotic flow, which is an example of electrokinetics, will be described with reference to FIG. In FIG. 13, two quartz glass plates 101 are arranged to face each other so that a gap 102 is formed between them. Electrodes 108 and 109 are disposed at both ends of the gap 102.

  The surface 103 of the quartz glass plate 101 is covered with silanol. In this state, when an electrolyte solution 104 that is an aqueous medium is injected into the gap 102, hydrogen ions move from the silanol to the electrolyte solution 104, and a negative charge 105 is generated on the surface 103. As a result, the cations 106 in the electrolyte solution 104 move to the surface 103 and a Helmholtz electric double layer 107 is generated.

  When a positive potential is applied to the electrode 108 and a negative potential is applied to the electrode 109 using the DC power source 110 in a state where the electric double layer 107 is generated, the cation 106 moves in the direction of the negative electrode 109. To do.

  When the cation 106 moves in the direction of the negative electrode 109, the electrolyte solution 104 itself moves in the direction of the negative electrode 109 due to the effect of the viscous flow. This phenomenon is electroosmotic flow.

  By connecting the gap 102 formed of the quartz glass plate 101 in this way to the flow path and applying a voltage to the gap 102 or both ends of the flow path, the electrolyte solution 104 of the entire flow path can be obtained by electroosmotic flow. Can be moved. Such a mechanism for moving the electrolyte solution 104 in the entire flow path is called an electroosmotic flow pump. As a flow path, a flow path formed of general quartz glass can be used instead of the gap 102 formed of the quartz glass plate 101.

  Next, electrophoresis, which is one of electrokinetics, will be described. Electrophoresis is a phenomenon in which charged particles or molecules move in an electric field. There are various uses for electrophoresis, but in molecular biology, it is important as a technique for separating deoxyribonucleic acid (DNA) and proteins.

  In order to move an object by using electrophoresis, for example, a sample containing an object such as DNA or protein is introduced into one end of a flow path provided with electrodes at both ends. Then, when a DC voltage is applied to the electrode provided in the flow path, the object moves through the sample by electrophoresis. For example, deoxyribonucleic acid molecules are negatively charged and move through the sample in the direction of the positive electrode.

  In this way, by moving the object in the sample toward the end of the flow path, the object can be separated from the sample, and the object can be detected.

  When the object is moved by electrokinetics such as electrophoresis or electroosmotic flow as described above, the electrode is usually provided in a buffered aqueous solution. In this state, when a voltage is applied to each electrode from an external power source, a potential difference is generated between the electrodes. This causes electrolysis in the buffered aqueous solution, and gas is generated at the electrode. The generated gas forms bubbles on the electrode surface. Normally, hydrogen gas is generated at the cathode (cathode), and oxygen gas is generated at the anode (anode). Further, the kind and amount of the generated gas vary depending on the composition of ions in the buffered aqueous solution.

  In an interface conductive device that moves an object by electrokinetics, if bubbles are formed on the electrode surface, a serious problem occurs.

  In general, when an object is moved using electrokinetics, an electrolyte solution (such as a buffer solution) having high electrical conductivity is often used as a driving liquid. In this case, when a DC voltage is applied to the electrodes, the current flowing between the electrodes increases. Accordingly, the generation of bubbles in the electrode is promoted.

  Patent Document 1 describes a bubble removing device for removing bubbles generated when an object is moved by electrophoresis. As shown in FIG. 14, this bubble removing apparatus includes a flow path 207 that circulates the solution in the electrophoresis tank 204 and a reaction tank 205 that is disposed in the flow path 207 and incorporates a catalyst layer supporting palladium. Including.

In the reaction tank 205, the gas (H ₂ and O ₂ ) generated at the electrodes 202a and 202b is bonded as water by the reaction of 2H ₂ + O ₂ → 2H ₂ O by the catalytic action of palladium. Thereby, the generated gas is removed, and it is possible to suppress the formation of bubbles on the electrode surface.

Separately, an ion conductive material is used as an electrode, and the ion conductive material is electrically connected to the electronic conductor outside the flow path, thereby making the gas generation point outside the flow path. Methods are also being considered. In this method, it is possible to suppress the generation of gas inside the flow path, and thus it is possible to suppress the formation of bubbles on the electrode surface.
JP-A-1-189555

  In the bubble removing apparatus described in Patent Document 1, mechanical components such as a reaction tank, a circulation pump, and a circulation channel have been added. However, when such mechanical components are added, there is a problem that the apparatus is enlarged. In addition, although the bubble removal apparatus of patent document 1 was devised supposing electrophoresis as electrokinetics, it is applicable also to an electroosmotic flow. However, the above problem also occurs in electroosmotic flow.

  Further, in the method using an ion conductive material as an electrode, it is possible to avoid the problem of gas generation inside the flow path, but the ion conductive material is electrically connected to the electronic conductor outside the flow path. There is a problem that the apparatus is complicated because it is necessary.

  Accordingly, an object of the present invention is to provide an electrokinetic device capable of reducing the generation of bubbles in an electrode while suppressing an increase in size and complexity of the device.

  The electrokinetic apparatus according to the present invention includes a flow path for fluid, a plurality of first electrodes provided in the flow path and electrically connected using the fluid, and the plurality of first electrodes. Voltage supply means for moving the fluid in the flow path by electrokinetics by applying a voltage between the first electrode and the first electrode, corresponding to each first electrode. Switching between a plurality of catalyst bodies for ionizing the gas generated at the electrodes, conduction means for conducting the catalyst bodies to each other, on / off of voltage application by the voltage supply means, and on / off of conduction by the conduction means Switching means.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce generation | occurrence | production of the bubble in an electrode, suppressing the enlargement and complication of an apparatus.

  Embodiments according to the present invention will be described below with reference to the drawings.

  A configuration of an electrokinetic device according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

  FIG. 1 is a plan view schematically showing the configuration on the glass substrate of the electrokinetic device of the present embodiment.

  In FIG. 1, a glass substrate 1 has a buffer solution introduction channel 4 in which a buffer solution inlet 2 is formed and a separation detection channel in which a buffer solution outlet port 3 is formed as a fluid channel. 5 are formed. Further, the glass substrate 1 is provided with a sample introduction flow path 8 in which the sample introduction port 6 is formed and a sample discharge flow path 9 in which the sample discharge port 7 is formed.

  The buffer solution introduction channel 4 and the separation detection channel 5 are connected to each other. For this reason, the buffer solution introduction port 2 and the buffer solution discharge port 3 are in fluid communication with each other via the buffer solution introduction channel 4 and the separation detection channel 5.

  The sample introduction channel 8 and the sample discharge channel 9 are connected to each other. For this reason, the sample introduction port 6 and the sample discharge port 7 are in fluid communication with each other via the sample introduction channel 8 and the sample discharge channel 9. Here, the connection location between the buffer solution introduction flow channel 4 and the separation detection flow channel 5 intersects the connection location between the sample introduction flow channel 8 and the sample discharge flow channel 9.

  An electrode 14 is provided in the sample introduction port 6. An electrode 15 is provided in the sample discharge port 7. The electrodes 14 and 15 are in fluid communication with each other via the sample introduction channel 8 and the sample discharge channel 9.

  In addition, an electrical wiring 22 is connected to the electrode 14, and an electrical wiring 23 is connected to the electrode 15.

  Electrodes 16 and 17 are provided in the separation detection flow path 5. The electrode 16 is provided at an upstream position closer to the buffer solution inlet 2 than the electrode 17. Further, the electrode 17 is provided at a location on the downstream side closer to the buffer solution outlet 3 than the electrode 16. The electrodes 16 and 17 are electrically connected to each other using the fluid in the separation detection flow path 5. Each of the electrodes 16 and 17 is an example of a first electrode.

  Further, a plurality of catalyst bodies for ionizing the gas generated at the electrodes are provided corresponding to the electrodes 16 and 17, respectively. In this embodiment, a catalyst layer (not shown) for ionizing the gas generated at the electrode is provided as a catalyst body on at least a part of the surface of each of the electrodes 16 and 17. The catalyst that forms the catalyst layer is, for example, palladium or platinum. The catalyst is not limited to palladium or platinum and can be changed as appropriate.

  In addition, electrical wirings 24 and 60 are connected to the electrode 16, and electrical wirings 25 and 61 are connected to the electrode 17.

  Electrodes 20 and 21 for measuring the result of separation of the sample by electrophoresis as an electric resistance value are provided on the terminal side of the separation detection channel 5 so as to sandwich the separation detection channel 5.

  In addition, an electrical wiring 28 is connected to the electrode 20, and an electrical wiring 29 is connected to the electrode 21.

  FIG. 2 is a cross-sectional view along a straight line connecting the buffer solution introduction port 2 and the buffer solution discharge port 3 of the electrokinetic device shown in FIG.

  Each of the buffer solution introduction channel 4, the separation detection channel 5, the sample introduction channel 8, and the sample discharge channel 9 is carved on the upper surface of the glass substrate 1. Each of the electrodes 14, 15, 16, 17, 20 and 21 is embedded in the glass substrate 1 so that at least a part of the surface is in contact with the fluid in the flow path.

  A glass plate 30 is bonded to the upper surface of the glass substrate 1. The glass plate 30 is provided with an inlet 31 and an outlet 32. The introduction port 31 communicates with the buffer solution introduction port 2, and the discharge port 32 communicates with the buffer solution discharge port 3. A sample tank 33 is attached to the inlet 31, and a sample tank 34 is attached to the outlet 32. The sample tanks 33 and 34 are liquid tanks and are formed of glass tubes. Each of the sample introduction port 6 and the sample discharge port 7 is provided with a sample tank (not shown) which is a liquid tank formed of a glass tube similar to the sample tanks 33 and 34.

  FIG. 3 is a plan view showing the configuration of the electrokinetic device of the present embodiment. In FIG. 3, the electrokinetic device includes a glass substrate 1, power supplies 41, 43 and 48, switches 42, 44, 49 and 62, ammeters 50, 63 and 64, electric wirings 22, 23, 24, 25, 28, 29, 60 and 61, and a control unit 70.

  Here, the electric wirings 24 and 25 and the power source 43 constitute a voltage supply unit that applies a voltage between the electrodes 16 and 17 to move the fluid in the separation detection flow path 5 by electrokinetics. In addition, the electrical wirings 60 and 61 constitute a conducting part that allows the catalyst layers to conduct with each other.

  The power supply 41 applies a voltage between the electrodes 14 and 15 via the electrical wirings 22 and 23. The switch 42 switches on / off of voltage application between the electrodes 14 and 15 in the power supply 41. When the switch 42 turns on the voltage application, the power supply 41 applies a positive potential to the electrode 14 and applies a negative potential to the electrode 15.

  The power source 43 applies a voltage between the electrodes 16 and 17 via the electric wirings 24 and 25 to move the fluid in the separation detection flow path 5 by electrokinetics. The switch 44 switches on and off the application of voltage between the electrodes 16 and 17 in the power supply 43. When the switch 44 is turned on, the power supply 43 applies a positive potential to the electrode 16 and applies a negative potential to the electrode 17.

  The ammeter 63 measures the current flowing between the electrodes 16 and 17 at least when a voltage is applied in the voltage supply unit. The ammeter 63 is an example of a first measuring unit.

  The conducting portion composed of the electric wirings 60 and 61 conducts the electrodes 16 and 17 and conducts the electrodes 16 and 17 to each other.

  The switch 62 switches on / off of conduction in the conduction unit. When the switch 62 is turned on, the electrodes 16 and 17 become conductive. The ammeter 64 measures the current flowing between the electrodes 16 and 17 at least during conduction by the switch 62. The ammeter 64 is an example of a second measuring unit.

  The power source 48 applies a voltage between the electrodes 20 and 21. The switch 49 controls voltage application by the power supply 48. When the switch 49 is turned on, the power supply 48 applies a positive potential to the electrode 20 and applies a negative potential to the electrode 21. The ammeter 50 measures the current value flowing between the electrodes 20 and 21 when a voltage is applied by the power supply 48, and outputs the current value to the outside.

  The control unit 70 is an example of a switching unit. Based on the current values measured by the ammeters 63 and 64, the control unit 70 switches on / off of voltage application by the electric supply unit and on / off of conduction by the conduction unit. Specifically, the control unit 70 controls on / off switching of the switches 44 and 62 to switch on / off of voltage application by the electricity supply unit and on / off of conduction by the conduction unit. At this time, the control unit 70 switches on / off of voltage application and conduction so that the dissolved amount per unit volume of the gas fluid generated at the electrodes 16 and 17 does not exceed the solubility of the gas.

  Next, the operation will be described.

  4 to 10 are explanatory diagrams for explaining the operation of the electrokinetic device. FIG. 11 is a flowchart for explaining the operation of the electrokinetic device. In the following description, the number of steps corresponds to the flowchart shown in FIG.

  As an initial state, it is assumed that the switch 62 is on and the other switches are off. When the switch 62 is on, the dissolved gas in the vicinity of the electrodes 16 and 17 is below a certain amount. The dissolved gas is typically oxygen and hydrogen. In addition, when it is guaranteed that the dissolved gas amount of the fluid introduced into the electrokinetic device is below a certain value, the switch 62 does not need to be turned on in the initial state.

  First, the buffer solution is put into the sample tank 33 provided at the buffer solution inlet 2. The buffer solution is filled into the buffer solution introduction channel 4, the separation detection channel 5, the sample introduction channel 8, and the sample discharge channel 9 by capillary force or the like (step S1). Next, the sample to be measured is put into a sample tank (not shown) provided at the sample introduction port 6 (step S2).

  Subsequently, as shown in FIG. 4, the switch 42 is turned on. When the switch 42 is turned on, the power supply 41 applies a voltage between the electrodes 14 and 15. As a result, an electroosmotic flow is caused in the sample introduction flow path 8. With this electroosmotic flow, the buffer solution filled in the sample introduction channel 8 is discharged from the sample discharge port 7, and the sample to be measured is injected into the sample introduction channel 8 (step S3).

  After the sample to be measured is injected into the sample introduction channel 8, the switch 42 is turned off. When the switch 42 is turned off, the application of voltage between the electrodes 14 and 15 by the power source 43 is stopped (step S4). As a result, the sample to be measured is injected into a portion located between the buffer solution introduction channel 4 and the separation detection channel 5.

  Here, as shown in FIG. 5, the switch 49 is turned on. When the switch 49 is turned on, the power supply 48 applies a voltage between the electrodes 20 and 21 (step S5).

  Next, the control unit 70 is operated. When operating, the control unit 70 turns off the switch 62 and then turns on the switch 44 as shown in FIG. 6 (step S6).

  When the switch 44 is turned on, the power supply 43 applies a voltage between the electrodes 16 and 17 disposed on both sides of the separation detection flow path 5. By applying this voltage, the sample to be measured located between the buffer solution introduction channel 4 and the separation detection channel 5 out of the sample to be measured injected into the sample introduction channel 8 becomes the separation detection channel. 5 is introduced into the separation detection flow path 5 by the action of the electroosmotic flow. The sample to be measured introduced into the separation detection flow path 5 moves in the direction of the separation detection flow path 5 from the electrode 16 to the electrode 17 by the action of the electroosmotic flow. The sample to be measured is subjected to electrophoresis while moving in the separation detection channel 5. Thereby, each component in the sample to be measured is separated according to the difference in ease of movement in the liquid.

Then, the control unit 70, the predetermined time T ₁ from the application of a voltage by the power source 43 between the electrodes 16 and 17 determines whether it has elapsed (step S7). This time T ₁ is set in advance according to the solubility of the gas generated in the electrodes 16 and 17 and the dissolved amount per unit volume of the gas. Specifically, the time T ₁ is set to a value at which the dissolved amount per unit volume of the gas does not exceed the solubility of the gas. The dissolved amount of gas per liquid unit volume is calculated by applying the current value measured by the ammeter 63 to “Faraday's electrolysis law” to be described later. In this embodiment, it is assumed that the time T ₁ is set to 0.2 seconds.

Control unit 70, when not elapsed time T _1, again executes the step S7, the time T ₁ is elapsed and turns off the switch 44 (step S8).

  Subsequently, when the control unit 70 turns off the switch 44, the control unit 70 turns on the switch 62 as shown in FIG. When the switch 62 is turned on, the electrodes 16 and 17 become conductive (step S9).

  When the electrodes 16 and 17 are electrically connected, in the electrode 16, oxygen generated when a positive potential is applied in step S <b> 6 returns to the hydroxyl ion again by the action of the catalyst provided in the electrode 16. . That is, electrons are given in response to oxygen that has aggregated on the surface of the electrode 16 and has become a bubble, and oxygen returns to hydroxyl ions while decomposing water. Thus, the electrode 16 is reduced.

  When the electrodes 16 and 17 are conducted, the electrode 17 is subjected to the action of the catalyst provided on the electrode 17 when a negative potential is applied in step S6, as in the case of the electrode 16. The generated hydrogen returns to hydrogen ions again. That is, electrons are deprived of hydrogen that has aggregated on the surface of the electrode 17 and started to form bubbles, and hydrogen returns to hydrogen ions. Thus, the electrode 17 is oxidized.

  At this time, since the potential difference between the electrodes 16 and 17 is eliminated, electroosmotic flow and electrophoresis do not occur in the separation detection flow path 5. That is, the functions of movement of the sample to be measured and separation of each component are suspended in the separation detection channel 5.

Then, when the switch 62 is turned on, the control unit 70 determines whether the time T ₂ has elapsed after the switch 62 is turned on and the electrodes 16 and 17 are turned on (step S10). This time T ₂ is determined according to the amount of gas generated at the electrodes 16 and 17 in step S7.

In the present embodiment, the control unit 70 determines the time T _{2 so} that the amount of gas generated at the electrodes 16 and 17 is substantially the same as the amount of gas to be ionized. More specifically, the control unit 70 determines that the integral value of the current value measured by the ammeter 64 over time T ₂ is substantially equal to the integral value of the current value measured by the ammeter 63 over time T _1. The time T ₂ is determined so that

Control unit 70, when not elapsed time T _2, then executes the step S10 again, when the time T ₂ has elapsed, as shown in FIG. 8, turns off the switch 62 (step S11).

  The control unit 70 counts the number of times the series of processes from step S6 to S11 has been performed, and determines whether or not the number of processes has reached a predetermined number N (step S12). In the present embodiment, the predetermined number N is set to 100.

  If the number of processes is not the predetermined number N, the control unit 70 executes step S6. Thereby, a series of processes from step S6 to S11 are repeated N times.

  Further, when the number of processing times reaches the predetermined number N, the control unit 70 turns off the switch 49 and turns on the switch 62 as shown in FIG. 9 (step S13).

  When the sample component separated by electrophoresis in the separation detection flow path 5 reaches the position of the electrodes 20 and 21, a voltage is applied between the electrodes 20 and 21 by the power supply 48, so that a change in the flowing current is detected. The flow of each sample component is detected. The change in current is measured by an ammeter 50. The operation from step S6 to step S11 is repeated N times, and the ammeter 50 is monitored until the switch 49 is finally turned off.

  When step S13 ends, the operation ends.

Hereinafter, a quantitative grasp of the gas generated by the electrolysis and a method for setting the times T ₁ and T ₂ will be described.

  In step S 6, when a voltage is applied between the electrodes 16 and 17 by the power supply 43, a positive potential is applied to the electrode 16 and a negative potential is applied to the electrode 17. At this time, water, which is the main composition of the buffer solution and the sample, is electrolyzed, oxygen is generated on the surface of the electrode 16 serving as the anode, and hydrogen is generated on the surface of the electrode 17 serving as the cathode.

  As is well known, the amount of gas generated by electrolysis follows the “Faraday electrolysis law”. That is, according to the first law of “Faraday's law of electrolysis”, the amount of the substance that is electrolyzed and deposited is proportional to the amount of electricity that has flowed into the fluid. According to the second law, the electrochemical equivalent is equal to the chemical equivalent. That is, the electrochemical equivalent is the same as the chemical equivalent.

  Equation (1) shows the second law of “Faraday's Law of Electrolysis”.

n = m / M = (I · t) / (z · F) (1)
Here, the meanings of the symbols are as follows.
n [mol]: substance amount,
m [g]: mass,
M [g / mol]: molecular weight,
I [A]: current,
t [s]: time,
z: ionization number,
F = 9.65 × 104 [C / mol]: Faraday constant.

As an example, the amount of hydrogen generated on the surface of the electrode 17 serving as a cathode is estimated under certain conditions. The conditions are as follows.
I = 0.005 [A],
t = 0.2 [s],
z = 1,
F = 9.65 × 104 [C / mol].

When this condition (numerical value) is used, the substance amount n = 1.04 × 10 ⁻⁸ [mol]. This amount of gas has a volume of 2.3 × 10 ⁻⁵ [L] = 0.23 [μL] at 0 ° C. and 1 atmosphere.

In this embodiment, the switch 44 is turned off after a time T ₁ after the voltage is applied between the electrodes 16 and 17 by the power source 43. The time T ₁ is set to 0.2 seconds. Considering the electrode 17, when the applied voltage is about 10 volts and a current of about 5 microamperes flows, the amount of hydrogen shown in the above-described calculation is generated. Specifically, the total amount of hydrogen is about a few microliters.

  Before the generated gas separates from the electrode 17, it is important to set the conditions so that the generated gas disappears by making the electrode 16 and the electrode 17 conductive. This condition varies depending on various factors such as the size of the electrode 17 and the size of the flow path.

In the present embodiment, the time T ₂ for conducting the electrodes 16 and 17 as described above is the time until the control unit 70 returns to the amount of gas substantially equal to the amount of gas generated at time T _1. It has been decided.

  For example, the controller 70 first turns on the switch 44 in step S6 when the number of processes is 1, and then switches the switch 44 in step S8 when the number of processes is the same. Integrate until is turned off.

  Subsequently, the control unit 70 integrates the current value measured by the ammeter 64 when the switch 62 is turned on in step S9 when the number of processes is the same.

Thereafter, the control unit 70 determines that the integrated value (referred to as the first integrated value) of the current value measured by the ammeter 64 is the current value measured by the ammeter 63 in step S10 when the number of processes is the same. It is determined whether or not the integrated value (referred to as the second integrated value) is reached. When the first integral value becomes the second integral value, the control unit 70 determines that the time T ₂ has elapsed, and when the first integral value has not reached the second integral value, the time T ₂ has not elapsed. Judge. Further, the control unit 70 measures the time from turning on the switch 62 to the first integration value is the second integral value at step S9, determines its time as the time T _2.

In step 10 when the number of processes is 2 or more, the control unit 70 determines whether the determined time T ₂ has elapsed after the switch 62 is turned on and the electrodes 16 and 17 are turned on.

FIG. 10 shows the relationship between the current value measured by the ammeter 63 when the electrodes 16 and 17 are conductive and the elapsed time. As shown here, the shorter the time T _{2, the} larger the amount of mobile charge per unit time when the electrodes 16 and 17 are conducting. Therefore, by setting T ₁ as short as possible and frequently switching between voltage application and conduction, the amount of charge per unit time that can move during T ₂ is large. For this reason, generation | occurrence | production of a bubble can be reduced efficiently.

  Further, the generated gas in the liquid is ionized by contacting the catalyst layer. Therefore, in order to efficiently ionize the gas, as much gas as possible should touch the catalyst layer in a short time. For this reason, if the surface area of the catalyst layer in contact with the fluid in the flow path is increased, gas ionization can be performed efficiently.

  In the present embodiment, the number of repetitions of the processing from steps S6 to S11 is set to 100, but this number is determined from the configuration of the electrokinetic device. Specifically, the number of times is set from the time required for the electroosmotic flow that changes according to the length of the separation detection flow path 5 and the time required for separating the target substance by electrophoresis.

Further, in this embodiment, the amount of gas generated in step S6, the amount of gas to be consumed is set substantially equal so that the value of the time T ₁ and T ₂ in step S9, it is not limited thereto . For example, even if the amount of gas consumed in step S9 is less than the amount of gas generated in step S6, the dissolved amount per unit volume of gas in the liquid in the flow path must exceed the solubility of the gas by the time step S13 is reached. That's fine.

  Next, the effect will be described.

  In the present embodiment, the voltage supply unit composed of the power supply 43 and the electric wirings 24 and 25 applies a voltage between the electrodes 16 and 17 to move the fluid in the flow path by interfacial conduction. Further, a catalyst body for ionizing the gas generated in each of the electrodes 16 and 17 is provided corresponding to each of the electrodes 16 and 17. The conduction part constituted by the electric wirings 60 and 61 conducts the catalyst bodies to each other. The control unit 70 switches on / off of voltage application by the voltage supply unit and on / off of conduction by the conduction unit.

  In this case, the gas generated in each of the electrodes 16 and 17 when a voltage is applied is ionized when the catalyst body is conducted. Therefore, the generation of bubbles can be reduced without providing a reaction tank, a circulation pump, and a circulation channel. In addition, it is possible to reduce the generation of bubbles without electrically connecting the ion electrodynamic material to the electronic conductor outside the channel. Therefore, it is possible to reduce the generation of bubbles in the electrode while suppressing the increase in size and complexity of the apparatus.

  In this embodiment, each catalyst body is provided on the surface of each of the electrodes 16 and 17.

  In this case, the apparatus configuration can be simplified, and the increase in size of the apparatus can be further suppressed.

  Further, the amount of gas generated at the electrode changes according to the value of the current flowing between the electrodes 16 and 17. Further, the amount of gas ionized by the catalytic action varies depending on the value of current flowing between the catalyst bodies. Therefore, the dissolved amount per unit volume of the generated gas varies depending on the current value flowing between the electrodes 16 and 17 and the current value flowing between the catalyst bodies.

  In this embodiment, the ammeter 63 measures the value of the current flowing between the electrodes 16 and 17 when a voltage is applied by the voltage supply unit. The ammeter 64 measures the value of current flowing between the catalyst bodies during conduction by the conduction unit. Based on the current value measured by each of ammeters 63 and 64, control unit 70 switches on / off of voltage application by the voltage supply unit and on / off of conduction by the conduction unit.

  For this reason, according to the dissolved amount per unit volume of the gaseous fluid which generate | occur | produced in the electrodes 16 and 17, it becomes possible to switch on / off of the application of the voltage by a voltage supply part, and on / off of the conduction | electrical_connection by a conduction | electrical_connection part. Therefore, the dissolved amount per unit volume of the gas fluid generated at the electrodes 16 and 17 can be prevented from exceeding the solubility of the gas. Therefore, the generation of bubbles can be further reduced.

  FIG. 12 is a plan view showing the configuration of the electrokinetic device according to the second embodiment of the present invention. In FIG. 12, components having the same functions as those in FIG.

  In FIG. 12, the electrokinetic device does not have the electrical wirings 60 and 61, the switch 62, and the ammeter 64, as compared with the electrokinetic device of the first embodiment shown in FIG. In addition, the electrokinetic device further includes electrical wirings 80 and 81, a switch 82, an ammeter 83, and electrodes 84 and 85, as compared with the electrokinetic device of Example 1 shown in FIG.

  The electrodes 84 and 85 are an example of a second electrode. Each of the electrodes 84 and 85 is provided corresponding to each of the electrodes 16 and 17. A catalyst layer for ionizing a gas generated at the electrode is provided as a catalyst body on at least a part of the surface of each of the electrodes 84 and 85 that contacts the fluid. The catalyst forming this catalyst layer is, for example, palladium or platinum. The catalyst is not limited to palladium or platinum and can be changed as appropriate. The electrodes 16 and 17 do not have to be provided with a catalyst layer.

  Regarding the operation of the electrokinetic device, in the electrokinetic device of the first embodiment, the switch 62 is read as the switch 82, and the ammeter 64 is read as the ammeter 83. Of the descriptions relating to the electrodes 16 and 17, the electrodes 16 and 17 may be read as the electrodes 84 and 85, respectively, where the static elimination and the catalytic action are described (steps S 9 and S 10).

  Next, the effect will be described.

  In this embodiment, a catalyst body for ionizing gas is provided on electrodes 84 and 85 different from electrodes 16 and 17. For this reason, the gas generated at the electrodes 16 and 17 can be ionized more efficiently. This is because, in Example 1, since the gas was ionized by the electrodes 16 and 17 where the gas was generated, the generated gas might flow downstream of the electrodes 16 and 17. In the present embodiment, for example, by disposing each of the electrodes 84 and 85 downstream of each of the electrodes 16 and 17, it becomes possible to capture the gas more reliably at the electrodes 84 and 85. Therefore, it is possible to reduce the generation of bubbles more efficiently.

  In each of the embodiments described above, the illustrated configuration is merely an example, and the present invention is not limited to the configuration.

It is the top view which showed typically the structure on the glass substrate of the electrokinetic apparatus of the 1st Example by this invention. It is sectional drawing of the flow-path part shown in FIG. It is the top view which showed typically the structure of the electrokinetic apparatus of Example 1 which concerns on this invention. FIG. 3 is a plan view for explaining the operation of the electrokinetic device according to the first embodiment. FIG. 3 is a plan view for explaining the operation of the electrokinetic device according to the first embodiment. FIG. 3 is a plan view for explaining the operation of the electrokinetic device according to the first embodiment. FIG. 3 is a plan view for explaining the operation of the electrokinetic device according to the first embodiment. FIG. 3 is a plan view for explaining the operation of the electrokinetic device according to the first embodiment. FIG. 3 is a plan view for explaining the operation of the electrokinetic device according to the first embodiment. FIG. 3 is a plan view for explaining the operation of the electrokinetic device according to the first embodiment. It is a flowchart for demonstrating operation | movement of an electrokinetic apparatus. It is the top view which showed typically the structure of the electrokinetic apparatus of Example 2 which concerns on this invention. It is explanatory drawing for demonstrating the principle of an electroosmotic flow. It is the block diagram which showed the bubble removal apparatus of patent document 1.

Explanation of symbols

4 Buffer solution introduction flow path 5 Separation detection flow path 16, 17, 84, 85 Electrode 43 Power supply 24, 25, 60, 61, 80, 81 Electrical wiring 63, 64, 83 Ammeter 70 Control unit

Claims (6)

A flow path for fluid, a plurality of first electrodes provided in the flow path and electrically connected using the fluid, and applying a voltage between the plurality of first electrodes, In an electrokinetic device including a voltage supply means for moving the fluid in the flow path by electrokinetics,
A plurality of catalyst bodies for ionizing the gas generated at the first electrode provided corresponding to each first electrode;
Conduction means for conducting the catalyst bodies to each other;
An electrokinetic apparatus comprising: switching means for switching on / off of voltage application by the voltage supply means and on / off of conduction by the conduction means. The electrokinetic device according to claim 1,
Each catalyst body is an electrokinetic apparatus provided on the surface of each first electrode. The electrokinetic device according to claim 1,
Each electrocatalyst is provided in the surface of the some 2nd electrode provided corresponding to each 1st electrode. In the electrokinetic device according to any one of claims 1 to 3,
A first measuring means for measuring a current value flowing between the electrodes when a voltage is applied by the voltage supply means;
A second measuring means for measuring a current value flowing between the catalyst bodies at the time of conduction by the conduction means,
Based on the current values measured by the first measuring means and the second measuring means, the switching means turns on and off the application of voltage by the voltage supply means and turns on and off by the conduction means. Switching electrokinetic device. In the electrokinetic device according to any one of claims 1 to 4,
The electrokinetic device, wherein the electrokinetic is electroosmotic flow. In the electrokinetic device according to any one of claims 1 to 4,
The electrokinetic apparatus, wherein the electrokinetic is electrophoresis.

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