JP2012189498A - Electric field generation device and electric field generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent corrosion of an electrode by suppressing occurrence of electrolysis and an electrochemical reaction when producing an electric field in one direction in a liquid.SOLUTION: An electric field generation device includes a container charged with a liquid, first and second electrodes arranged in the liquid charged in the container with a prescribed gap therebetween so as to be partly immersed in the liquid, and an AC generator that is connected to the first and second electrodes and applies an asymmetric AC current between both the electrodes. In the liquid, the AC generator generates either one of an electric field substantially directed from the first electrode to the second electrode, and an electric field substantially directed from the second electrode to the first electrode.

Description

  The present invention relates to an electric field generating apparatus and an electric field generating method for generating an electric field in a liquid. The present invention also relates to a floating body moving device and a floating body moving method for moving a solid floating in a liquid, an electrophoresis device and an electrophoresis method, an electroosmotic flow pump, and an operation method thereof.

  Conventionally, in order to separate and analyze molecules such as charged particles and proteins, an electrophoresis method has been used in which a pair of electrodes is immersed in a solution containing the molecules and a DC voltage is applied between the electrodes. In this way, when a DC voltage is applied between the pair of electrodes, an electric field in one direction is generated in the solution, so that charged particles or the like can be moved in the direction of one electrode.

For example, Patent Document 1 describes an electrophoresis apparatus used to determine the base sequence of DNA.
In the electrophoresis apparatus of Patent Document 1, electrode layers accommodated in an electrolytic solution are arranged at both ends of a slab-like electrophoresis gel corresponding to a solution, and an electrophoresis power source for applying an electrophoresis voltage is connected to the electrode layers. . The electrophoresis power source is a DC power source. When a unidirectional DC voltage (electric field) is applied between the electrode layers, a DC current flows in one direction, and the DNA fragment sample to be analyzed injected into the electrophoresis gel becomes the electrophoresis gel. It is separated by running inside.
In addition, a device that arranges a pair of electrodes in a liquid and applies a DC voltage between the electrodes to generate a unidirectional electric field in the liquid moves an electroosmotic flow pump or charged fine particles. It is used in various fields such as devices.

JP-A-7-151687

However, when an electric field is generated in a liquid by passing a direct current between the electrodes, the current flows in one direction for a long time, causing the liquid to be electrolyzed or the electrode to corrode due to an electrochemical reaction. was there.
Furthermore, these reactions also cause a problem that bubbles are generated in the liquid or the liquid is contaminated. In addition, these problems lead to sample contamination in the electrophoresis apparatus, and the electroosmotic flow pump causes malfunction due to bubbles.

  Accordingly, the present invention has been made in consideration of the above-described circumstances, and an electric field that can generate an electric field in one direction in the liquid without causing electrolysis or electrochemical reaction of the liquid. It is an object of the present invention to provide a generation device and an electric field generation method.

The present invention includes a container into which a liquid is injected, and a first electrode and a second electrode that are arranged at predetermined intervals so that at least a part of the container is immersed in the liquid injected into the container. An alternating current generator connected to the first electrode and the second electrode and applying an asymmetrical alternating current between the two electrodes, wherein the alternating current generator is substantially in the liquid in the first electrode The present invention provides an electric field generating device that generates one of an electric field directed from the first electrode to the second electrode or substantially an electric field directed from the second electrode to the first electrode.
According to this, since an asymmetrical alternating current is applied between the first electrode and the second electrode, a substantially unidirectional electric field can be generated in the liquid, and the liquid undergoes electrolysis. It hardly occurs or causes an electrochemical reaction, and corrosion of the electrode can be suppressed.

Here, in the electric field generator, the first electrode and the second electrode are disposed so as to be in direct contact with the liquid injected into the container, and the asymmetrical alternating current is connected to the first electrode. A value Veff = 式 V (t) dt obtained by integrating the voltage V (t) between the second electrode (t is time) over one AC period.
Is substantially 0 and has no substantial DC component.
According to this, since a net direct current does not flow between the first electrode and the second electrode, liquid electrolysis and electrochemical reaction are less likely to occur, and the electrode can be reliably prevented from corroding. .

In the electric field generator, at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid.
According to this, since at least one of the first electrode and the second electrode is covered with the insulating film, a direct current does not flow between the two electrodes. Therefore, the liquid hardly undergoes electrolysis or electrochemical reaction, and the electrode can be more reliably prevented from corroding.

The present invention also provides a container into which a liquid in which an object floats is injected, and a first electrode disposed at a predetermined interval so that at least a part of the container is immersed in the liquid injected into the container. And an AC generator connected to the first electrode and the second electrode, and applying an asymmetrical alternating current between the two electrodes, and by the asymmetrical alternating current applied by the alternating current generator, The object floating in the liquid is moved either from the first electrode to the second electrode or from the second electrode to the first electrode. A floating body moving device is provided.
According to this, since an asymmetrical alternating current is applied between the first electrode and the second electrode, an object floating in the liquid can be moved in one direction, and the liquid undergoes electrolysis. It is possible to suppress the corrosion of the electrode.

Here, in the floating body moving device, the first electrode and the second electrode are both arranged so as to be in direct contact with the liquid, and the asymmetrical alternating current is the first electrode and the second electrode. Veff = ∫V (t) dt, which is obtained by integrating the voltage V (t) between and Vt (t is time) over one AC period.
Is substantially 0 and has no substantial DC component.
According to this, since a net direct current does not flow between the first electrode and the second electrode, liquid electrolysis and electrochemical reaction are less likely to occur, and the electrode can be reliably prevented from corroding. .

In the floating body moving device, at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid.
In the above embodiment, since at least one of the first electrode and the second electrode is covered with the insulating film, no direct current flows between the two electrodes. Therefore, the liquid hardly undergoes electrolysis or electrochemical reaction, and the electrode can be more reliably prevented from corroding.

The present invention also provides a migration tank into which a liquid containing a sample is injected, and a first gap arranged at a predetermined interval so that at least a part is immersed in the liquid injected into the migration tank. An electrode and a second electrode; and an AC generator connected to the first electrode and the second electrode, and applying an asymmetrical alternating current between the two electrodes, by the asymmetrical alternating current applied by the alternating current generator The sample contained in the liquid is migrated between the first electrode and the second electrode in the liquid, and at least one of the first electrode and the second electrode is covered with an insulating film, It is an object of the present invention to provide an electrophoresis apparatus that is not in direct contact with a liquid.
According to this, since an asymmetrical alternating current is applied between the first electrode and the second electrode, the sample can be electrophoresed, and the liquid is electrolyzed during the electrophoresis. It is possible to prevent bubbles from being generated, and it is possible to prevent the electrode from being corroded by the electrochemical reaction and contaminating the liquid. Therefore, more accurate analysis of the sample can be performed by electrophoresis.

The present invention also provides an electrophoretic particle disposed in a space sandwiched between a first electrode and a second electrode, which are opposed to each other with a predetermined interval, and the first electrode and the second electrode. And an electrophoretic element comprising a plurality of capsules containing the dispersion liquid, an AC generator connected to the first electrode and the second electrode, and applying an asymmetrical alternating current between the two electrodes, The present invention provides an electrophoretic display device that moves electrophoretic particles in each capsule in the direction of one electrode by asymmetrical alternating current.
According to this, since asymmetrical alternating current is applied between the first electrode and the second electrode, the electrophoretic particles in each capsule can be continuously moved in the direction of one electrode, When the position of the capsule is a pixel, display based on electrophoresis can be performed.

In addition, the present invention provides a flow path for flowing a liquid, a first electrode and a second electrode that are spaced apart from each other in an upstream portion and a downstream portion of the flow path, and have a plurality of holes. An AC generator connected to the electrode and the second electrode, and applying an asymmetrical alternating current between the electrodes, and applying the asymmetrical alternating current to flow the liquid flowing into the flow path An electroosmotic flow pump is provided that transports from a first electrode in an upstream portion to a second electrode in a downstream portion.
According to this, since an asymmetrical alternating current is applied between the first electrode and the second electrode, the liquid in the flow path can be transported in one direction, and the liquid is electrolyzed and bubbled. Can be prevented, and the electrode can be prevented from corroding due to electrochemical reaction. Therefore, since a mechanism for removing bubbles is not required, the structure of the electroosmotic flow pump can be simplified, and the reliability of the electroosmotic flow pump can be increased.

Here, in the electroosmotic flow pump, the first electrode and the second electrode are disposed so as to be in direct contact with the liquid that has flowed into the flow path, and the asymmetrical alternating current is obtained by A value Veff = 式 V (t) dt obtained by integrating the voltage V (t) (t is time) between the electrode and the second electrode over one AC period.
Is substantially 0 and has no substantial DC component.
According to this, since a net direct current does not flow between the first electrode and the second electrode, liquid electrolysis and electrochemical reaction are less likely to occur, and the electrode can be reliably prevented from corroding. .

In the electroosmotic pump, at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid.
According to this, since at least one of the first electrode and the second electrode is covered with the insulating film, a direct current does not flow between the two electrodes. Therefore, the liquid is not electrolyzed and bubbles are not generated, and it is possible to more reliably prevent the electrode from being corroded by the electrochemical reaction.
Furthermore, in the electroosmotic flow pump, a porous electroosmotic material may be provided in the flow path between the first electrode and the second electrode.

Moreover, the electroosmotic pump of the present invention can be provided in a fuel cell.
Furthermore, the electroosmotic flow pump of the present invention may be used as a device for driving a cooling pump or a chemical solution supply device.

  The present invention also provides a preparation step for injecting a liquid into a container, and an arrangement step in which the first electrode and the second electrode are arranged at predetermined intervals so that at least a part of each is immersed in the liquid. And an asymmetrical alternating current is applied between the first electrode and the second electrode, and an electric field that substantially flows from the first electrode to the second electrode in the liquid, or substantially the second And an electric field generating step of generating any one of the electric fields directed from the first electrode to the first electrode.

  According to this invention, since an asymmetrical alternating current is applied between the first electrode and the second electrode, a substantially unidirectional electric field can be generated in the liquid, and the liquid undergoes electrolysis. It is possible to suppress the corrosion of the electrode.

Further, the present invention is the electric field generation method described above, wherein both the first electrode and the second electrode are disposed so as to be in direct contact with the liquid, and the asymmetrical alternating current is the same as that of the first electrode and the second electrode. The value of the following equation obtained by integrating the voltage V (t) between two electrodes (t is time) over one period of alternating current Veff = ∫V (t) dt
Is substantially 0 and has no substantial DC component.
According to this, since a net direct current does not flow between the first electrode and the second electrode, liquid electrolysis and electrochemical reaction are less likely to occur, and the electrode can be reliably prevented from corroding. .

Further, at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid.
According to this, since at least one of the first electrode and the second electrode is covered with the insulating film, a direct current does not flow between the two electrodes. Therefore, the liquid hardly causes electrolysis or electrochemical reaction, and it is possible to more reliably prevent the electrode from corroding.

Further, as the asymmetrical alternating current, it is preferable to use rectangular waves having different high potential duration and low potential duration.
According to this, a circuit for generating asymmetrical alternating current is relatively simple, and a substantially one-directional electric field can be efficiently generated in the liquid.

Further, as the asymmetrical alternating current, it is preferable to use a triangular wave or a sawtooth wave having different rising time and falling time.
According to this, a circuit for generating asymmetrical alternating current is relatively simple, and a substantially one-directional electric field can be efficiently generated in the liquid.

According to the present invention, the preparation step for injecting the liquid in which the object is suspended into the container and the first electrode and the second electrode are spaced apart from each other at least by a predetermined distance. Asymmetrical alternating current is applied between the first electrode and the second electrode, and the object floating in the liquid moves from the first electrode to the second electrode. Or a floating body moving method comprising a moving step of moving any one of the movements from the second electrode to the first electrode.
According to this, since an asymmetrical alternating current is applied between the first electrode and the second electrode, an object floating in the liquid can be moved in one direction, causing the liquid to undergo electrolysis, There is almost no electrochemical reaction, and corrosion of the electrode can be suppressed.

Here, in the floating body moving method, both the first electrode and the second electrode are arranged so as to be in direct contact with the liquid, and the asymmetrical alternating current is generated by the first electrode and the second electrode. Veff = （V (t) dt, which is obtained by integrating the voltage V (t) (t is time) over a period of AC.
Is substantially 0 and has no substantial DC component.
According to this, since a net direct current does not flow between the first electrode and the second electrode, liquid electrolysis and electrochemical reaction are less likely to occur, and the electrode can be reliably prevented from corroding. .

In the floating body moving method, at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid.
According to this, since at least one of the first electrode and the second electrode is covered with the insulating film, a direct current does not flow between the two electrodes. Therefore, the liquid hardly undergoes electrolysis or electrochemical reaction, and the electrode can be more reliably prevented from corroding.

According to the present invention, at least a part of the preparation step for injecting a liquid containing a sample to be moved by electrophoresis into the electrophoresis tank and the first electrode and the second electrode are immersed in the liquid. Placing the sample at a predetermined interval, applying an asymmetrical alternating current between the first electrode and the second electrode, so that the sample is in a liquid with the first electrode and the second electrode An electrophoretic step in which at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid. is there.
According to this, since an asymmetrical alternating current is applied between the first electrode and the second electrode, the sample can be electrophoresed, and the liquid is electrolyzed during the electrophoresis. It is possible to prevent bubbles from being generated, and it is possible to prevent the electrode from being corroded by the electrochemical reaction and contaminating the liquid. Therefore, more accurate analysis of the sample can be performed by electrophoresis.

Further, according to the present invention, the first electrode and the second electrode are arranged separately from each other in the upstream portion and the downstream portion in the flow path of the electroosmotic flow pump. An asymmetrical alternating current is applied between the first electrode and the second electrode in the downstream part from the first electrode in the upstream part in the channel. A method of operating a featured electroosmotic pump is provided.
According to this, since an asymmetrical alternating current is applied between the first electrode and the second electrode, the liquid in the flow path can be transported in one direction, and the liquid is electrolyzed and bubbled. Can be prevented, and the electrode can be prevented from corroding due to electrochemical reaction. Therefore, since a mechanism for removing bubbles is not required, the structure of the electroosmotic flow pump can be simplified, and the reliability of the electroosmotic flow pump can be increased.

Here, in the operation method of the electroosmotic flow pump, both the first electrode and the second electrode are disposed so as to be in direct contact with the liquid, and the asymmetrical alternating current is the second electrode and the second electrode. Veff = ∫V (t) dt, which is obtained by integrating the voltage V (t) (t is time) with the other electrode over one AC period.
Is substantially 0 and has no substantial DC component.
According to this, since a net direct current does not flow between the first electrode and the second electrode, it is possible to prevent liquid from being electrolyzed and generating bubbles, and the electrode is corroded by an electrochemical reaction. Can be prevented more reliably.

The electroosmotic pump operating method is characterized in that at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid.
According to this, since at least one of the first electrode and the second electrode is covered with the insulating film, a direct current does not flow between the two electrodes. Therefore, the liquid is not electrolyzed to generate bubbles, and the electrode can be more reliably prevented from being corroded by the electrochemical reaction.

  According to this invention, since an asymmetrical alternating current is applied between the first and second electrodes, which are a pair of electrodes in the liquid, a substantially unidirectional electric field can be generated in the liquid. A unidirectional electric field due to a direct current is not continuously applied to the liquid, and electrolysis and electrochemical reaction can be prevented from occurring in the liquid, and corrosion of the electrode can be suppressed.

It is explanatory drawing of one Example of a symmetrical alternating current waveform. It is explanatory drawing of one Example of the waveform of the asymmetrical alternating current of this invention. It is explanatory drawing of one Example of the waveform of the asymmetrical alternating current of this invention. It is explanatory drawing of one Example of the determination method of being asymmetrical alternating current. It is a schematic block diagram of one Example of the electric field generator of this invention. It is a schematic block diagram of the electric field generator of Embodiment 2 of this invention. It is explanatory drawing of one Example of the waveform of the asymmetrical alternating current of this invention. It is explanatory drawing of the electric field generation | occurrence | production phenomenon at the time of applying a DC voltage between the electrodes in a liquid. It is explanatory drawing of the simulation model of asymmetrical alternating current of this invention. It is explanatory drawing of the simulation model of asymmetrical alternating current of this invention. It is a wave form diagram of one Example of the asymmetrical rectangular wave used by 1st simulation of this invention. It is a graph of the electric charge amount induced by the 1st simulation of this invention. It is a graph of the electric charge amount induced by the 1st simulation of this invention. It is a graph of the strength of the electric field in the liquid in the first simulation of the present invention. In the 1st simulation of this invention, it is a graph which shows the relationship between an average electric field and the constant n. In the 1st simulation of this invention, it is a graph of the time change of the position of the object in a liquid. It is a wave form diagram of one Example of the asymmetrical rectangular wave used by the 2nd simulation of this invention. In the 2nd simulation of this invention, it is a graph of the time change of the position of the object in a liquid. It is a wave form diagram of one Example of the symmetrical rectangular wave used by the 3rd simulation of this invention. In the 3rd simulation of this invention, it is a graph of the time change of the position of the object in a liquid. It is a wave form diagram of one Example of the asymmetrical triangular wave used by the 4th simulation of this invention. It is a graph of the electric charge amount induced by the 4th simulation of this invention. It is a graph of the electric charge amount induced by the 4th simulation of this invention. It is a graph of the electric field strength in the liquid in the 4th simulation of this invention. It is a graph which shows the relationship between an average electric field and the constant n in the 4th simulation of this invention. In the 4th simulation of this invention, it is a graph of the time change of the position of the object in a liquid. It is a schematic block diagram of the floating body moving apparatus of Embodiment 3 of this invention. It is a schematic block diagram of the floating body moving apparatus of Embodiment 4 of this invention. It is a schematic block diagram of the floating body moving apparatus of Embodiment 5 of this invention. It is a schematic block diagram of the electrophoresis apparatus of Embodiment 6 of this invention. It is a schematic block diagram of the electrophoretic display device of Embodiment 7 of this invention. It is a schematic block diagram of the electroosmotic flow pump of Embodiment 8 of this invention. It is a schematic block diagram of the electroosmotic flow pump of Embodiment 9 of this invention. It is a schematic block diagram of the electroosmotic flow pump of Embodiment 10 of this invention. It is a schematic block diagram of the fuel cell of Embodiment 11 of this invention. It is a schematic block diagram of the cooling pump of Embodiment 12 of this invention. It is a schematic block diagram of the chemical | medical solution supply apparatus of Embodiment 13 of this invention.

<Definition of terms>
First, the definition of “asymmetrical alternating current” used in the present invention will be described with reference to FIGS.
FIG. 1 illustrates an asymmetric waveform that is not asymmetric, ie, symmetrical. 2 and 3 exemplify an asymmetrical alternating current waveform. FIG. 4 is a diagram for explaining a specific method for determining whether or not asymmetric.

FIG. 1 illustrates four non-asymmetrical, ie, symmetrical, alternating waveforms (a graph showing the relationship between voltage V and time t).
FIG. 1A shows a symmetric sine wave. On the graph, 111 is a point where the voltage takes the minimum value, 112 is a point where the voltage takes the maximum value, and 113 is a point where the voltage takes the minimum value again. A portion 114 (section 111 to 112) of the waveform is a step-up process, and another portion 115 (section 112 to 113) of the waveform is a step-down process. From point 111 to point 113 is one cycle of alternating current.

Here, the reference | standard which judges the sine wave of Fig.1 (a) to be symmetrical is demonstrated with reference to Fig.4 (a) and (b).
FIG. 4 (a) is a reproduction of FIG. 1 (a). In FIG. 4 (b), the voltage step-up process 114 of the waveform in FIG. 4 (a) is extracted and the voltage axis is inverted (114r). Naturally, this 114r exactly overlaps the waveform step-down process 115. That is, an alternating current in which the step-up process and the step-down process completely overlap is referred to as non-asymmetrical alternating current or symmetrical alternating current.

FIG. 1B shows a symmetric rectangular wave. In this case, the number of points at which the voltage is minimum is not one, but may be 121a or 121c, or 121b between these two points. Similarly, the number of points at which the voltage is maximum is not one, but may be 122a or 122c, or 122b between these two points.
However, in order to determine whether or not it is asymmetric as described above, it is necessary to determine the range of the waveform step-up process 124 and the step-down process 125. In the future, if there are multiple points where the voltage is minimum (maximum), the final point will be adopted. That is, the step-up process 124 is between 121a and 122a, and the step-down process is between 122a and 123a. Since the step-up process 124 (section 121a to 122a) and the step-down process 125 (section 122a to 123a) are completely overlapped by inverting the voltage axis, the alternating current of the rectangular wave in FIG. is there.

  FIG. 1C shows a symmetrical triangular wave. The step-up process 134 (section 131 to 132) and the step-down process 135 (section 132 to 133) are completely overlapped by inverting the voltage axis. The waveform in FIG. 1 (d) is complex, but it is still a symmetrical alternating current. This is because the step-up process 144 (section 141 to 142) and the step-down process 145 (section 142 to 143) are completely overlapped by inverting the voltage axis.

On the other hand, FIG. 2 illustrates four asymmetrical AC waveforms.
FIG. 2A shows an asymmetrical alternating current although the waveform changes sinusoidally. 4 (c) and 4 (d), even if the step-up process 214 (section 211 to 212) is inverted on the voltage axis (214r), the step-down process 215 (section 212 to 213) Because they do not overlap.
FIG. 2B shows an asymmetric rectangular wave in which the time at high potential (high potential duration) and the time at low potential (low potential duration) are different. This is because even if the step-up process 224 (section 221 to 222) is inverted on the voltage axis, it does not overlap with the step-down process 225 (section 222 to 223).

FIG. 2C shows an asymmetric triangular wave. This is because even if the step-up process 234 (section 231 to 232) is inverted on the voltage axis, it does not overlap with the step-down process 235 (section 232 to 233). An asymmetric triangular wave is a triangular wave having a different rise time and fall time.
The waveform in FIG. 2 (d) is complex, but is still asymmetrical alternating current. This is because even if the step-up process 244 (section from 241 to 242) is inverted on the voltage axis, it does not overlap with the step-down process 245 (section from 242 to 243).
In addition, although not shown, a sawtooth wave having a different rise time and fall time may be used as the asymmetrical alternating current.

FIG. 3 is an example of an asymmetrical alternating current whose period or amplitude varies with time.
In FIG. 3A, the period increases with time. Even if the step-up process 314 (section 311 to 312) is inverted on the voltage axis, it does not overlap with the step-down process 315 (part 312 to 313).
In FIG. 3B, the amplitude increases with time. Even if the step-up process 324 (section from 321 to 322) is inverted on the voltage axis, it does not overlap with the step-down process 325 (section from 322 to 323).

To summarize the above, as illustrated in FIGS. 2 and 3, asymmetrical alternating current is defined as alternating current that does not overlap even if the alternating voltage step-up process and the step-down process are reversed. Also called asymmetrical alternating current.
Hereinafter, an apparatus and a method for generating an electric field substantially in one direction in a liquid using asymmetrical alternating current will be described using specific examples.

<Embodiment 1>
An electric field generation apparatus and an electric field generation method for generating an electric field in one direction in a liquid according to the first embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a schematic cross-sectional view of an apparatus (electric field generator) 1100 that generates an electric field in one direction in a liquid.
The container 1111 is filled with the liquid 1112. At least a part of the first electrode 1113 and the second electrode 1114 is immersed in the liquid 1112. An AC power source 1115 (also referred to as an AC generator) that generates asymmetrical AC is connected to the first electrode 1113 and the second electrode 1114.

Here, the container 1111 may be any container that can hold the liquid 1112.
The liquid 1112 preferably has a low ion concentration in order to effectively generate a unidirectional electric field. For example, ethanol, methanol, alcohols such as IPA (Isopropyl Alcohol), and organic solvents such as benzine and acetone are preferable. When water is used, it is preferable to use pure water, non-ionized water or the like.

The first electrode 1113 and the second electrode 1114 only need to have sufficient conductivity.
Note that the first electrode 1113 and the second electrode 1114 are arranged so as to face each other, whereby the direction and strength of the electric field between the two electrodes can be made uniform. Therefore, as shown in the embodiments described later, when moving a charged object in a liquid in one direction or performing electrophoresis, it is possible to accurately control the object and the object of electrophoresis. .
As the electrode material, for example, a metal such as copper, gold, tungsten, or aluminum, or a semiconductor such as silicon to which an impurity imparting conductivity is added can be used.

  The shape of the electrode is, for example, a flat plate, and the size and area of the electrode are about 5 cm × 5 cm. The pair of electrodes are arranged opposite each other by a predetermined distance, and the distance between the electrodes is, for example, about 10 cm. However, the shape and arrangement of the electrodes are not limited to this, and electrodes having a net shape, a ring shape, or a lump shape may be arranged so as to sandwich a region where an electric field is to be generated. Further, the distance between the electrodes may be determined according to the size of the region where the electric field is to be generated, and may be several μm to several tens of cm.

  As the asymmetrical alternating current generated by the alternating current power source 1115 and applied to the first electrode 1113 and the second electrode 1114, for example, the one shown in FIG. 2 or FIG. 3 can be used. The AC voltage value V in FIGS. 2 and 3 is a voltage applied to the first electrode 1113 using the second electrode 1114 as a reference voltage. At this time, for example, when the asymmetrical alternating current shown in FIG. 2 is applied, the direction of the electric field substantially generated in the liquid 1112 is rightward (direction of arrow 1117 in FIG. 5).

The preferred frequency of the asymmetrical alternating current varies depending on the type of liquid. In general, the liquid contains ions, and the higher the ion concentration in the liquid, the faster the electric field generated in the liquid disappears in response to the potential change of the electrode. When the voltage change of the asymmetrical alternating current (proportional to the frequency) is longer than the time when the electric field generated in the liquid disappears, the electric field can hardly be generated in the liquid. For this reason, the frequency is lowered for a liquid having a low ion concentration, and the frequency is increased for a liquid having a high ion concentration.
As an example, when IPA is used as the liquid, the frequency is preferably 5 Hz to 50 kHz, and when pure water is used as the liquid, the frequency is 500 Hz to 5 MHz. However, when the ion concentration is high due to liquid contamination, it is necessary to increase the frequency.

When the ion concentration of the liquid 1112 is high, when an asymmetrical alternating current is applied to the first electrode 1113 and the second electrode 1114, the effect of inhibiting an electric field from being generated in one direction in the liquid 1112 becomes stronger.
This is because there are many ions in the vicinity of the surfaces of the first electrode 1113 and the second electrode 1114, so that the first electrode This is because the change in the number of charges in the vicinity of the surfaces of 1113 and the second electrode 1114 quickly follows.
Therefore, when the ion concentration of the liquid 1112 is high, it is necessary to increase the frequency of the asymmetrical alternating current. The behavior of ions in the liquid 1112 when the ion concentration of the liquid 1112 is high will be described later at the end of the simulation result.

A preferable voltage for the asymmetrical alternating current is appropriately determined depending on the required electric field strength. For example, when the distance between the electrodes is 1 cm, a voltage of 1 V to 500 V can be used.
In this way, by applying asymmetrical alternating current to the first electrode 1113 and the second electrode 1114, an electric field is generated in the liquid 1112 substantially in one direction. The reason will be described based on a simulation result described later.

By the way, the problem that the liquid is electrolyzed or the electrode corrodes due to the electrochemical reaction is determined solely by the direct current component flowing between the electrodes, and is hardly a problem with alternating current.
In the electrochemical reaction (electric corrosion), when a direct current flows, an oxidation reaction occurs at the anode and corrosion proceeds, but a reduction reaction occurs at the cathode and no corrosion occurs.

On the other hand, when an alternating current flows, the oxidation reaction and the reduction reaction of the same degree occur alternately, so that the two electrodes hardly corrode. The same applies to electrolysis.
Actually, reaction products move by diffusion, so the oxidation reaction and reduction reaction do not completely cancel at low frequencies, but in general, electrochemical reactions and electrolysis in alternating current are far more than in direct current. Small.
Therefore, the fact that an electric field can be generated in one direction in the liquid by alternating current means that the electric field can be generated in one direction in the liquid with almost no electrochemical reaction or electrolysis.

Thus, when direct current is passed, corrosion of the anode occurs, whereas when alternating current is passed, electrochemical reaction and electrolysis hardly occur, and therefore, corrosion of the electrode hardly occurs.
Further, in the case of alternating current, in both cases of symmetric alternating current and asymmetrical alternating current, oxidation reaction and reduction reaction occur alternately, so that electrode corrosion hardly occurs.

The step of generating an electric field in the liquid 1112 substantially in one direction mainly includes the following steps.
(1) a preparation step for injecting the liquid 1112 into the container 1111;
(2) an arrangement step of arranging the first electrode 1113 and the second electrode 1114 at a predetermined interval so that at least a part thereof is immersed in the liquid 1112;
(3) An asymmetrical alternating current is applied between the first electrode 1113 and the second electrode 1114, and the electric field that substantially flows from the first electrode 1113 to the second electrode 1114 in the liquid 1112, or the second An electric field generating step of generating one of the electric fields from the electrode 1114 toward the first electrode 1113;

A substantially unidirectional electric field can be generated in the liquid 1112 by applying an asymmetrical alternating current between the two electrodes 1113 and 1114 using the method or apparatus as described above.
In asymmetrical alternating current, the direction of the electric field is alternately reversed instantaneously. However, as described above, the steps of step-up and step-down do not overlap, so that the electric field is substantially unidirectional. Substantially unidirectional means that when the electric field vector generated in the liquid is integrated for one period of an asymmetrical alternating current, an integer period, or a sufficiently long time, the electric field vector does not become zero and has a finite magnitude. It means to face the direction. Therefore, it does not mean that the direction of the electric field vector is always in one direction. Actually, when an asymmetrical alternating current is applied, the direction of the electric field vector is reversed at the period of the asymmetrical alternating current.

When a substantially unidirectional electric field is generated in this way, oxidation and reduction occur alternately as described above, so that the liquid is hardly electrolyzed, and an electrochemical reaction hardly occurs. However, when a symmetrical alternating current is applied, the electrode is similarly unlikely to corrode, but an electric field in one direction cannot be generated.
Therefore, when an asymmetrical alternating current is applied, a unidirectional electric field can be generated in the liquid, similar to a direct current, and the liquid is electrolyzed, or the electrode is corroded by an electrochemical reaction, similar to the symmetrical alternating current. Can be suppressed.

  In this embodiment mode, since both the first electrode 1113 and the second electrode 1114 are in direct contact with the liquid 1112, if a direct current is applied between the two electrodes, a direct current flows. Therefore, the asymmetrical alternating current does not have a substantial direct current component, that is, Veff obtained by integrating the voltage V (t) between the first electrode and the second electrode over one period of the alternating current is substantial. Is preferably 0. This is because a net direct current does not flow between the two electrodes in this way, so that problems such as liquid electrolysis or electrode corrosion due to electrochemical reaction can be avoided more reliably.

  A preferable example of the asymmetrical alternating current is an asymmetric rectangular wave (a rectangular wave having a high potential duration and a low potential duration different) as shown in FIG. This is because a circuit for generating such a rectangular wave is relatively simple, and a substantially unidirectional electric field can be efficiently generated in the liquid. In the example of FIG. 2B, the high potential duration is short and the low potential duration is long. However, when the high potential duration is long and the low potential duration is short, it is substantially unidirectionally generated in the liquid. The direction of the electric field can be reversed.

As the asymmetrical alternating current, an asymmetric triangular wave (triangular wave or sawtooth wave having a different rising time and falling time) as shown in FIG. 2C may be used. A circuit for generating such a triangular wave is relatively simple, and an electric field in a substantially one direction can be efficiently generated in the liquid. In this example, the rise time is short and the fall time is long, but if the rise time is long and the fall fall time is shortened, the direction of the electric field in one direction generated in the liquid can be reversed. .
The reason why the waveforms shown in FIGS. 2B and 2C are preferable will be described in detail together with the interpretation of the simulation results described later.

<Embodiment 2>
An electric field generation apparatus and an electric field generation method for generating an electric field in one direction in a liquid according to a second embodiment of the present invention will be described with reference to FIG.
The present embodiment is different from the first embodiment in that at least one of the first electrode and the second electrode is covered with an insulating film.

FIG. 6 is a schematic cross-sectional view of an apparatus 1200 that generates an electric field in one direction in the liquid according to the present embodiment.
The container 1211 is filled with the liquid 1212. At least a part of the first electrode 1213 and the second electrode 1214 is immersed in the liquid 1212. The first electrode 1213 and the second electrode 1214 are covered with an insulating film 1216, and an AC power supply 1215 that generates asymmetrical AC is connected to the first electrode 1213 and the second electrode 1214.

Here, the container 1211 may be anything that can hold the liquid 1212. The liquid 1212 preferably has a low ion concentration. For example, alcohols such as ethanol, methanol and IPA, and organic solvents such as benzine and acetone are preferable. When water is used, it is preferable to use pure water, non-ionized water or the like. The first electrode 1213 and the second electrode 1214 only need to have sufficient conductivity.
Also in this case, as in the first embodiment, in order to make the direction and strength of the electric field between the two electrodes uniform, the first electrode 1213 and the second electrode 1214 are opposed to each other. It is preferable to arrange. This makes it possible to accurately control the movement of the charged object in the liquid in one direction and the movement of the object to be electrophoresed.

As the insulating film 1216, a silicon oxide film, a silicon nitride film, a resin thin film, or the like can be used.
The insulating film 1216 is formed so as to cover the entire electrode. For example, when the electrode is formed of a semiconductor material such as silicon added with a metal such as copper, gold, tungsten, or aluminum or an impurity imparting conductivity, 10 nm. A silicon oxide film having a thickness of about 2 μm may be formed. The insulating film may be formed by a known prior art, for example, a CVD (Chemical Vapor Deposition) method.

  As the asymmetrical alternating current generated by the alternating current power source 1215 and applied to the first electrode 1213 and the second electrode 1214, for example, the one shown in FIG. 2 or FIG. 3 can be used. 2 and 3 is a voltage applied to the first electrode 1213 using the second electrode 1214 as a reference voltage. At this time, for example, when the asymmetrical alternating current shown in FIG. 2 is applied, the direction of the electric field substantially generated in the liquid 1212 is rightward (direction of the arrow 1217 in FIG. 6).

Moreover, you may use the alternating current of the waveform shown in FIG. 7, for example as asymmetrical alternating current. The waveforms shown in FIGS. 7 (a), (b), (c) and (d) are the same as the waveforms shown in FIGS. 2 (a), (b), (c) and (d), respectively, with direct current components Vsa and Vsb. , Vsc and Vsd.
In the waveform shown in FIG. 2, the average of the voltage over one period of AC is 0, but it is not 0 in the waveform shown in FIG. However, since the first electrode 1213 and the second electrode 1214 are covered with the insulating film 1216, no direct current flows between the two electrodes. Therefore, even if the waveform is as shown in FIG. 7, a substantially unidirectional electric field can be generated in the liquid 1212 without any particular adverse effect.

  In this embodiment mode illustrated in FIG. 6, the first electrode 1213 and the second electrode 1214 are both covered with the insulating film 1216, but one of the electrodes may be covered with the insulating film 1216. This is because even in this case, it is possible to prevent a direct current from flowing between the two electrodes.

What is necessary is just to set the preferable frequency and voltage of asymmetrical alternating current similarly to Embodiment 1. FIG.
In Embodiment 2, since at least one of the first electrode and the second electrode is covered with an insulating film, a direct current does not flow between the two electrodes. That is, since direct electron transfer occurs between the electrode and the liquid, no oxidation reaction or reduction reaction occurs.
Therefore, the problem that the liquid is electrolyzed or the electrode is corroded by an electrochemical reaction can be reliably prevented.

In addition, since at least one of the first electrode and the second electrode is covered with the insulating film, electrons do not reach the second electrode directly from the first electrode, and current does not flow. Therefore, the electric power consumed in this system is only due to charge / discharge of the capacitance formed by the insulating film covering the electrodes. Therefore, the power consumption can be significantly reduced, and the generation of Joule heat can be significantly reduced.
In the case of the second embodiment, the waveforms shown in FIG. 2B and FIG. 2C are preferable.

<Simulation>
Hereinafter, the simulation result of the electric field generated in the liquid and the motion of the charged object when such an asymmetrical alternating current is applied to two electrodes in the liquid will be described.
(1) Simulation Model A simulation result of an electric field generated when an asymmetrical alternating current is applied to two electrodes immersed in a liquid and a motion of a charged object will be described with reference to FIGS.

FIG. 8 is a diagram illustrating a phenomenon that occurs when a constant DC voltage is applied to two electrodes immersed in a liquid from time T = 0.
It is assumed that the liquid 1212 is filled between the first electrode 1213 and the second electrode 1214. The first electrode 1213 and the second electrode 1214 are each covered with an insulating film 1216. In this case, no current flows between the two electrodes. A power source 1215 is connected to the first electrode 1213 and the second electrode 1214.
When a voltage starts to be applied from the power source 1215 to the first electrode 1213 and the second electrode 1214 at T = 0, the liquid 1212 has a direction indicated by an arrow 1217 as shown in FIG. An electric field is generated.

  In the liquid, there are positive ions and negative ions whose concentration depends on the type of the liquid. Therefore, after time T1 has elapsed from the start of voltage application, as shown in FIG. 8B, on the insulating film 1216 covering the first and second electrodes, the sign opposite to the charge induced in the respective electrodes. The charge begins to collect. The electric charges induced on the insulating film 1216 terminate the electric lines of force generated from the electric charges induced in the respective electrodes, so that the strength of the electric field in the liquid 1212 gradually decreases with time.

After a sufficient time T2 has elapsed from the start of voltage application, as shown in FIG. 8C, the lines of electric force generated from the charges induced in the respective electrodes are caused by the charges induced on the insulating film 1216. Since it is completely terminated, the electric field strength in the liquid 1212 becomes zero.
The time (time constant) required for the electric field in the liquid to become almost zero depends on the concentration of ions present in the liquid, and the smaller the ion concentration, the longer the time. For example, in IPA, it is within 10 seconds, and in pure water, it is within 0.1 seconds. In water in which salts are dissolved, it becomes even shorter.

As described above, since movable ions exist in the liquid and can be collected on the insulating film of the electrode, conventionally, even if a voltage is applied to the electrode immersed in the liquid, there is only one in the solution. It has been difficult to generate a directional electric field continuously.
In addition, if a DC voltage is applied using a bare electrode that is not covered with an insulating film, a unidirectional electric field can be generated continuously in the liquid. However, if the unidirectional electric field is sustained, the liquid is electrolyzed. However, there has been a problem that the electrode is corroded by an electrochemical reaction.
Note that if an AC voltage is applied between two electrodes covered with an insulating film, an AC electric field can be generated in the liquid. When alternating current is applied between the two electrodes, when the reciprocal of the frequency is smaller than the above time constant, the electric charge induced in the electrode cannot follow the change in the electrode potential, so the electric field penetrates into the liquid. . However, the time average of the electric field in the liquid is 0, and it has been said that a unidirectional electric field cannot be generated in the liquid.

9 and 10 are explanatory diagrams of simulation models.
As shown in FIG. 9, the first electrode 1313 and the second electrode 1314 are each covered with an insulating film 1316. A space between the two electrodes 1313 and 1314 covered with the insulating film 1316 is filled with the liquid 1312. A power source 1315 capable of generating an arbitrary waveform is connected to the first electrode 1313 and the second electrode 1314. A charged object 1318 is suspended in the liquid 1312. The following simulation is considered using such a model.

A ground potential (GND) is applied to the second electrode 1314, and a voltage V (t) is applied to the first electrode 1313 at time t. When the system is not originally charged, the amount of charge induced on the surface of the first electrode 1313 is q _e (t), and the amount of charge induced on the insulating film 1316 covering the first electrode 1313 is q _s ( t), the amount of charge induced on the second electrode 1314 is −q _e (t), and the amount of charge induced on the insulating film 1316 covering the second electrode 1314 is −q _s (t). Become.
The dielectric constant of the insulating film 1316 is ε _d ε _o , and the dielectric constant of the liquid 1312 is ε _s ε _o . Here, ε _d and ε _s are relative dielectric constants of the insulating film 1316 and the liquid 1312, respectively, and ε _o is a dielectric constant in a vacuum. Further, the strength of the electric field in the liquid is E (t).

である。
ただし、ｄ_d1、ｄ_d2およびｄ_sは、それぞれ第１の電極１３１３を覆う絶縁膜１３１６の厚さ、第２の電極１３１４を覆う絶縁膜１３１６の厚さ、および液体１３１２の厚さである。電極の面積は１とした。 If the capacitance at both ends of the insulating film 1316 on the first electrode 1313 is C _d1 , the capacitance at both ends of the insulating film 1316 on the second electrode 1314 is C _d2 , and the capacitance at both ends of the liquid 1312 is C _s ,

It is.
Here, d _d1 , d _d2, and d _s are the thickness of the insulating film 1316 covering the first electrode 1313, the thickness of the insulating film 1316 covering the second electrode 1314, and the thickness of the liquid 1312, respectively. The area of the electrode was 1.

であらわされる。
一方、液体１３１２を導電体と考えて、Ｃ_d1とＣ_d2の２つの容量を直列に接続した場合の全体容量Ｃ_Bは、

であらわされる。 At this time, the capacity C _A of the entire model in which three capacitors C _d1 , C _s, and C _d2 are connected in series is

It is expressed.
On the other hand, assuming that the liquid 1312 is a conductor, the total capacity C _B when two capacitors C _d1 and C _d2 are connected in series is:

It is expressed.

Here, a simulation guideline when the power supply 1315 generates an arbitrary waveform will be described with reference to FIG.
First, the waveform is considered divided every short time _Δt . An arbitrary waveform is approximated by a step-like step by considering two steps of a voltage changing step for instantaneously changing the voltage and a voltage constant step for not changing the voltage at each time _Δt .

(A) Voltage change step In this voltage change step, the voltage changes instantaneously by ΔV (t). At this time, ions in the liquid cannot move following the change in voltage. That is, q _s (t) and −q _s (t) do not change. However, since the charge of the electrode can move sufficiently faster than the ions in the liquid, q _e (t) and −q _e (t) change immediately following the voltage change ΔV (t). At this time, the capacitance between the two electrodes behaves as if C _A.
From the above, the following equation is established in the voltage change step.
Δq _e (t) = C _A ΔV (t) (6)
Δq _s (t) = 0 (7)
Here, Δq _e (t) and Δq _s (t) represent amounts by which q _e (t) and q _s (t) change due to the voltage change ΔV (t) at time t, respectively.

(B) Constant voltage step In this voltage change step, the time Δt passes without the voltage changing. When the voltage does not change, as described in FIG. 8, ions in the liquid move so as to weaken the electric field in the liquid, that is, approach the equilibrium state, and q _s (t) changes. The equilibrium state is a state where the electric field in the liquid is zero, and the liquid may be regarded as a conductor. Therefore, the capacitance between the two electrodes can be regarded as C _B. Further, as q _s (t) changes, Δq _e (t) also changes.

From the above, the change in q _s (t) can be expressed by the following equation.

Where q _eq (t) is the equilibrium value of q _s (t) at time t,
q _eq (t) = C _B V (t) (9)
Satisfy the relationship.

n is an amount that defines the rate of change of q _s (t), the relationship between the displacement _{{q s (t) -q eq} (t)} of equilibrium of q _s (t). If n = 1, the rate of change of q _s (t) increases as the deviation between the equilibrium q _s (t) is large, and the rate of change is proportional to the displacement of equilibrium (a linear relationship is there).
On the other hand, when 0 <n <1, the rate of change depends on the deviation from the equilibrium state (that is, the rate of change increases as the deviation in the equilibrium state increases), but the rate of change is proportional to the deviation from the equilibrium state. No (not in a linear relationship) a is a quantity indicating the speed at which q _s (t) approaches q _eq (t).
As the ion concentration in the liquid is higher, q _s (t) can be changed more quickly, so a becomes larger.

としてあらわされる。 On the other hand, the rate of change of q _e (t) can be obtained from the rate of change of q _s (t) as follows. First, in time, the voltage V (t) applied between the two electrodes is the sum of the voltages applied across C _d1 , C _s and C _d2 ,

It is expressed as.

となる。 Taking the rate of change on both sides,

It becomes.

であるから、（１１）式と（１２）式から、

となり、ｑ_e(t)の変化率とｑ_s(t)の変化率の関係を得ることができる。 On the other hand, in the constant voltage step,

Therefore, from the equations (11) and (12),

Thus, the relationship between the change rate of q _e (t) and the change rate of q _s (t) can be obtained.

とあらわされる。 The electric field strength E (t) in the liquid at time t is

It is expressed.

(C) Motion of a charged object in a liquid The force F (t) received by a charged object in a liquid is q _ob , the viscous resistance coefficient c, and the velocity of the object v (t), where m is the mass of the object and a (t) is the acceleration of the object,
F (t) = q _ob E (t) −cν (t) = ma (t) (15)
By solving this equation of motion, the motion of the object in the liquid can be described.
Considering a spherical object having a radius r in a liquid having a viscosity η, when the Reynolds number is small, the viscous resistance coefficient c is expressed by 6πηr according to Stokes' theorem.

(2) Simulation Results Hereinafter, simulation results will be described using several AC waveforms as examples.
The constants used in this simulation are as follows.
The mass m of the object is 1.57 × 10 ⁻¹⁴ [kg], the radius r of the object is 1 × 10 ⁻⁷ [m], and the substantial charge amount q _ob of the object is 3.72 × 10 ⁻¹⁴ [C]. The viscosity of the liquid is 8 × 10 ⁻⁴ [Ps], the dielectric constant ε _d of the insulating film on the electrode is 4, and the thicknesses d _d1 and d _d2 of the insulating film on the electrode are 4 × 10 ⁻⁸ [m]. The relative dielectric constant ε _s of the liquid is 20, the thickness d _{s of the} liquid is 1 × 10 ⁻² [m], and the constant a is 10.
Further, unless otherwise specified, the constant n is 0.8, q _s and the rate of change of _{(t), q s (t} ) shifted {q _s and equilibrium (t) -q _eq (t )} Is non-linear.

[Results of First Example]
In the first embodiment, as shown in FIG. 11, an asymmetric rectangular wave having an amplitude of 200 V and a frequency of 5 Hz (a rectangular wave having a high potential duration and a low potential duration different) is applied to the first electrode 1313 and the second electrode. 1314. V (t) is the potential of the first electrode with respect to the second electrode 1314. It is assumed that no voltage is applied before time 0.

At this time, q _s (t) and q _e (t) change as shown in FIGS. 12 and 13, respectively. Each changes periodically except for the vicinity of time 0 when the application of the voltage is started. As shown in FIG. 14, the electric field strength E (t) in the liquid changes periodically except for the vicinity of time 0 when the voltage application is started.

Here, FIG. 15 shows the relationship between the average electric field E _av when a sufficient time has elapsed from the start of voltage application and a steady state is reached, and a constant n representing non-linearity.
The average electric field E _av was obtained by averaging the electric field E (t) over one AC period when a sufficient time had elapsed from the start of voltage application. The fact that the average electric field E _av is not 0 indicates that a substantially unidirectional electric field exists in the liquid.

When the constant n representing the non-linearity is 1 (no non-linearity exists), E _av is 0, and there is only a pure AC electric field in the liquid.
On the other hand, as n becomes smaller than 1, that is, as the nonlinearity becomes stronger, E _av becomes larger and the electric field in one direction in the liquid becomes stronger. This is the essence of the present invention, substantially unidirectional electric field generated in a liquid, q _s and the rate of change of _{(t), q s (t} ) shift the equilibrium of {q _s ( t) −q _eq (t)}. Note that E _av is positive indicates that the electric field in one direction is substantially downward in FIG.

FIG. 16 shows the time change of the position x (t) (vertical direction in FIG. 10) of the charged object placed in the liquid.
The object moves in the negative direction (upward in FIG. 10) at time 0, and then moves in the positive direction (downward in FIG. 10) while vibrating. This is because the time average E _av of the electric field E (t) is positive. From this, it can be seen that applying asymmetrical alternating current between the two electrodes moves the charged object in one direction.

As is clear from the above, even when the electrode is covered with an insulating film and no current flows in the liquid, by applying an asymmetrical alternating current between the electrodes, the electrode is substantially unidirectional in the liquid. It is possible to generate an electric field and move the object.
The experiment confirmed that the object in the liquid moves in one direction due to the asymmetrical square wave, and the direction coincided with the direction predicted by the simulation.

[Results of Second Example]
In the second embodiment, as shown in FIG. 17, an asymmetric rectangular wave having an amplitude of 200 V and a frequency of 5 Hz (a rectangular wave having a high potential duration and a low potential duration different) is applied to the first electrode 1313 and the second electrode. 1314. A difference from the first case is that a DC bias is added to the waveform shown in FIG. 11 so that V (t) in FIG. 17 is averaged over one period to be zero.

FIG. 18 shows the time change of the position x (t) of the charged object placed in the liquid.
Although the behavior immediately after the voltage application is different from that in the first example (FIG. 16), the object still moves in the positive direction while vibrating. Further, the moving speed in the positive direction is exactly the same as in the first example.
This means that if the electrode is covered with an insulating film, adding a DC component to the asymmetrical AC will affect the electric field generated inside the liquid and the movement of the charged object floating inside the liquid. It shows no. This was confirmed in actual experiments.

[Results of Third Example]
This third embodiment applies symmetrical alternating current, and is an embodiment shown for comparison with the first and second embodiments.
In the third embodiment, as shown in FIG. 19, a symmetrical rectangular wave with an amplitude of 200 V and a frequency of 5 Hz is applied between the first electrode 1313 and the second electrode 1314.
FIG. 20 shows the time change of the position x (t) of the charged object placed in the liquid.
The object vibrates but does not move in one direction. That is, with a symmetrical alternating current, a substantial electric field cannot be generated in one direction in the liquid, and an object cannot be moved substantially.

[Results of Fourth Example]
As shown in FIG. 21, the fourth embodiment is an asymmetric triangular wave (a triangular wave or a sawtooth wave having a rising time and a falling time different from each other) having an amplitude of 200 V and a frequency of 5 Hz.
In this example, the voltage changes abruptly during the step-up process and gradually changes during the step-down process.
At this time, q _s (t) and q _e (t) change as shown in FIGS. 22 and 23, respectively. Each changes periodically except for the vicinity of time 0 when the application of the voltage is started. As shown in FIG. 24, the electric field strength E (t) in the liquid changes periodically except for the vicinity of time 0 when the voltage application is started.

Here, FIG. 25 shows the relationship between the average electric field E _av when a sufficient time elapses from the start of voltage application and becomes a steady state, and a constant n representing nonlinearity.
When the constant n representing the non-linearity is 1 (no non-linearity exists), E _av is 0, and there is only a pure AC electric field in the liquid.
On the other hand, as n becomes smaller than 1, that is, as the nonlinearity becomes stronger, E _av becomes larger and the electric field in one direction in the liquid becomes stronger. This is the same as in the case of the first example (FIG. 15), but the shape of the curve of the graph is different.

FIG. 26 shows the time change of the position x (t) of the charged object placed in the liquid.
The object moves in the positive direction while vibrating. This is because the time average E _av of the electric field E (t) is positive.
When the waveform of FIG. 21 is deformed and an asymmetrical alternating current is applied in which the voltage changes slowly during the step-up process and changes rapidly during the step-down process, the direction of motion of the object may be in the opposite direction. Although it is expected from simulation, it has been confirmed in actual experiments.

In summary, the following can be predicted from the simulation results.
(1) When an asymmetrical alternating current is applied to the two electrodes, a substantially unidirectional electric field can be generated in the liquid, but a symmetrical alternating current is not possible.
(2) When asymmetrical alternating current is applied to the two electrodes, a charged object floating in the liquid can be moved in one direction, but not symmetrical alternating current.
(3) These effects are derived from the fact that the charge induction speed on the insulating film on the electrode is not proportional to the magnitude of deviation from the equilibrium state.

According to this simulation model and simulation results, the reason why the asymmetrical alternating current generates a substantially unidirectional electric field in the liquid can be interpreted as follows.
The asymmetrical alternating current is an alternating current that does not overlap even when the voltage axis of one of the alternating current step-up process and the step-down process is reversed, as already defined.
When such asymmetrical alternating current is applied to the electrodes, with a step-up process and the step-down process, q _s (t) shift the equilibrium of _{{q s (t) -q eq} (t)} are different. In this simulation model, nonlinearity was introduced between the rate of change of q _s (t) and {q _s (t) −q _eq (t)}. For this reason, even if the rate of change of q _s (t) and E (t), which is linked by the equations (13) and (14), are averaged over one AC period, it is not 0, and the liquid is substantially unidirectional. The electric field is generated.

From the above, it can be seen that the preferred asymmetrical alternating current is an alternating current whose voltage changes abruptly during the step-up process or step-down process. At the moment when the voltage suddenly changes, {q _s (t) −q _eq (t)} increases, the rate of change of q _s (t), and {q _s (t) −q _eq (t)} This is because the non-linearity between the two increases. From this, an asymmetrical rectangular wave and a triangular wave like FIG.2 (b) and FIG.2 (c) are preferable, and it has been confirmed by experiment that an effect is large.

Even when there is no insulating film on the electrode, by applying asymmetrical alternating current between the two electrodes, a substantially unidirectional electric field is generated in the liquid, and the charged object is unidirectionally It is possible to move to.
However, in this case, in order to suppress the corrosion of the electrode, it is preferable that the asymmetrical alternating current does not have a substantial direct current component. That is, the first electrode and the V _eff obtained by integrating over the voltage V (t) in one cycle of the AC between the second electrode is _{V eff = ∫V (t) dt} = 0 (16)
It is preferable that
By setting the integral value to 0 in this way, a net direct current does not flow between the two electrodes, so that the liquid is hardly electrolyzed and an electrochemical reaction hardly occurs. Therefore, it can suppress that an electrode corrodes.

By the way, when the time for q _s (t) to reach an equilibrium state (time constant proportional to the reciprocal of a) is shorter than the reciprocal of the frequency of the asymmetrical alternating current, the electric field cannot penetrate into the liquid. Does not occur. Further, in order for q _s (t) to change, ions scattered in the liquid need to move in the liquid and collect on the electrode, so the time constant becomes shorter as the ion concentration of the liquid is higher.
Therefore, when the ion concentration in the liquid is high, it is necessary to increase the frequency of the asymmetrical alternating current because the electric potential of the electrode needs to be changed more quickly in order to make the electric field penetrate into the liquid and generate an electric field in one direction. There is.
On the other hand, when the ion concentration in the liquid is low, the time constant is large and q _s (t) is easily moved away from the equilibrium state (ie, {q _s (t) −q _eq (t)} is increased). Therefore, an electric field in one direction is likely to be generated.
For the above reasons, it is preferable that the ion concentration in the liquid is low, because an electric field in one direction can be efficiently generated in the liquid and the frequency of the asymmetrical alternating current can be lowered.

<Embodiment 3>
A floating body moving apparatus and a floating body moving method for moving an object floating in a liquid according to a third embodiment of the present invention will be described with reference to FIG.
FIG. 27 shows a schematic cross-sectional view of an apparatus 2100 for moving an object floating in a liquid according to the present embodiment.
The container 2111 is filled with the liquid 2112. At least a part of the first electrode 2113 and the second electrode 2114 is immersed in the liquid 2112. An AC power supply 2115 that generates asymmetrical AC is connected to the first electrode 2113 and the second electrode 2114.

Here, the container 2111 may be any container that can hold the liquid 2112 as in the first embodiment. As in the first embodiment, the liquid 2112 preferably has a low ion concentration.
Similarly, the asymmetrical alternating current applied to the first electrode 2113 and the second electrode 2114 may be the one shown in FIGS. For example, when the asymmetrical alternating current shown in FIG. 2 is applied using the second electrode 2114 as a reference voltage, the direction of the electric field substantially generated in the liquid 2112 is rightward (the direction of the arrow 2117 in FIG. 27).
Therefore, when the object 2118 floating in the liquid is negatively charged, as shown in FIG. 27, the object 2118 moves to the left (the direction of the arrow 2119 in FIG. 27). When the object 2118 is positively charged, it moves in the opposite direction (rightward).

What is necessary is just to set the preferable frequency and voltage of asymmetrical alternating current similarly to Embodiment 1. FIG.
The object 2118 floating in the liquid only needs to be substantially charged.
The term “substantially charged” means that the charge generated in the object is the sum of the charge induced at the interface between the object 2118 and the liquid 2112 and the charge that is induced in the liquid near the object by the charge and moves with the solid. It means that it can be. In other words, it can be said that the zeta potential in the liquid is not zero.
When a substantially uncharged object is used, the zeta potential of the object can be changed using a nonionic surfactant.
Specific examples of the object are, for example, dielectric fine particles, semiconductor fine particles, metal fine particles, fine semiconductor devices, cells, DNA, RNA, proteins, and the like having a size of nanometer to 1 mm or less.

  In this manner, by applying an asymmetrical alternating current to the first electrode 2113 and the second electrode 2114, an electric field is generated substantially in one direction in the liquid 2112, and the object 2118 floating in the liquid 2112 is Can be moved in the direction. The principle of movement is the same as in the above simulation.

The step of generating an electric field in the liquid 1112 substantially in one direction mainly includes the following steps.
(1) a preparation step for injecting the liquid 2112 in which the object 2118 is suspended into the container 2111;
(2) an arrangement step of arranging the first electrode 2113 and the second electrode 2114 at a predetermined interval so that at least a part of the first electrode 2113 and the second electrode 2114 are immersed in the liquid 2112;
(3) An asymmetrical alternating current is applied between the first electrode 2113 and the second electrode 2114 to move the object 2118 floating in the liquid 2112 from the first electrode 2113 to the second electrode 2114, or A moving step of moving the object from the second electrode 2114 to the first electrode 2113;

By applying an asymmetrical alternating current between the two electrodes 2113 and 2114 using the method or apparatus as described above, the object 2118 floating in the liquid 2112 can be moved in one direction.
Therefore, in order to move an object floating in the liquid in one direction, an electric field in one direction is substantially applied by asymmetrical alternating current, so that the liquid is prevented from being electrolyzed and the electrode is formed by an electrochemical reaction. Corrosion can be suppressed.

Also in this embodiment, since the first electrode 2113 and the second electrode 2114 are in direct contact with the liquid 2112, a direct current flows when a direct current is applied between the two electrodes. Accordingly, as in the first embodiment, in order to avoid the occurrence of corrosion, the asymmetrical alternating current does not have a substantial direct current component, that is, the voltage V between the first electrode and the second electrode. It is preferable that Veff obtained by integrating (t) over one AC period is substantially zero.
For the same reason as in the first embodiment, in order to efficiently move an object floating in the liquid in one direction, the waveform shown in FIG. 2B or 2C is preferable as the asymmetrical alternating current. .

<Embodiment 4>
A floating body moving apparatus and a floating body moving method for moving an object floating in a liquid according to a fourth embodiment of the present invention will be described with reference to FIG.
The present embodiment is different from the third embodiment in that at least one of the first electrode and the second electrode is covered with an insulating film.

FIG. 28 shows a schematic cross-sectional view of an apparatus 2200 for moving an object floating in a liquid according to the present embodiment.
The container 2211 is filled with the liquid 2212. At least a part of the first electrode 2213 and the second electrode 2214 is immersed in the liquid 2212. The first electrode 2213 and the second electrode 2214 are covered with an insulating film 2216, and an AC power supply 2215 that generates asymmetrical AC is connected to the first electrode 2213 and the second electrode 2214.

Here, the container 2211 may be any container that can hold the liquid 2212 as in the first embodiment. The liquid 2212 preferably has a low ion concentration. As the insulating film 2216, as in Embodiment 2, a silicon oxide film, a silicon nitride film, a resin thin film, or the like can be used.
Similarly, the asymmetrical alternating current applied to the first electrode 2213 and the second electrode 2214 may be the one shown in FIGS. For example, when the asymmetrical alternating current shown in FIG. 2 is applied using the second electrode 2214 as a reference voltage, the direction of the electric field substantially generated in the liquid 2212 is rightward (the direction of the arrow 2217 in FIG. 28).
Therefore, when the object 2218 floating in the liquid is negatively charged, as shown in FIG. 28, the object 2218 moves to the left (the direction of the arrow 2219 in FIG. 28). When the object 2218 is positively charged, the object 2218 moves in the opposite direction (rightward).

  Further, as in the second embodiment, the waveform alternating current shown in FIG. 7 may be used for the asymmetrical alternating current. Since the first electrode 2213 and the second electrode 2214 are covered with an insulating film 2216, a direct current does not flow between the two electrodes, so even if the waveform is as shown in FIG. An object 2218 floating in 2212 can be moved in one direction. In this embodiment mode, either electrode may be covered with the insulating film 2216.

What is necessary is just to set the preferable frequency and voltage of asymmetrical alternating current similarly to Embodiment 1. FIG.
In addition, the object 2218 floating in the liquid only needs to be substantially charged. A specific example of the object may be the same as that shown in Embodiment Mode 3.
As described above, even when at least one of the electrodes is covered with the insulating film, an electric field is applied substantially in one direction in the liquid 2212 by applying asymmetrical alternating current to the first electrode 2213 and the second electrode 2214. And the object 2218 floating in the liquid 2212 can be moved in one direction.

In Embodiment 4, since at least one of the first electrode and the second electrode is covered with an insulating film, a direct current does not flow between the two electrodes. Therefore, the problem that the liquid is electrolyzed or the electrode is corroded by an electrochemical reaction can be reliably prevented. In addition, since at least one of the first electrode and the second electrode is covered with the insulating film, electrons do not reach the second electrode directly from the first electrode, and current does not flow. Therefore, the electric power consumed in this system is only due to charge / discharge of the capacitance formed by the insulating film covering the electrodes. Therefore, the power consumption can be significantly reduced, and the generation of Joule heat can be significantly reduced.
In the case of the fourth embodiment, the waveforms shown in FIGS. 2B and 2C are preferable.

<Embodiment 5>
A floating body moving apparatus and a floating body moving method for moving an object floating in a liquid according to a fifth embodiment of the present invention will be described with reference to FIG.
This embodiment is different from the fourth embodiment in that the first electrode and the second electrode are formed on two opposing substrates, and the object floating in the liquid is between the two electrodes. Is moving in one direction.

FIG. 29 shows a schematic cross-sectional view of an apparatus 2300 for moving an object floating in a liquid according to the present embodiment.
The first substrate 2321 and the second substrate 2322 are opposed to each other, and the liquid 2312 is filled therebetween. A first electrode 2313 is formed on the surface of the first substrate 2321 on the side in contact with the liquid 2312. A second electrode 2314 is formed on the side of the second substrate 2322 in contact with the liquid 2312.
An insulating film 2316 is formed on the surfaces of the first electrode 2313 and the second electrode 2314 to prevent a direct current from flowing between the first electrode 2313 and the second electrode 2314. An AC power source 2315 that generates asymmetrical AC is connected to the first electrode 2313 and the second electrode 2314 on the side not covered with the insulating film 2316.

Here, as the first substrate 2321 and the second substrate 2322, an insulator such as glass, resin, or ceramic can be used.
As in the first embodiment, the liquid 2312 preferably has a low ion concentration.
Similarly, the asymmetrical alternating current applied to the first electrode 2313 and the second electrode 2314 may be the one shown in FIGS. For example, when the asymmetrical alternating current shown in FIG. 2 is applied using the second electrode 2314 as a reference voltage, the direction of the electric field substantially generated in the liquid 2312 is downward (the direction of the arrow 2317 in FIG. 29).
Therefore, when the object 2318 floating in the liquid is negatively charged, it moves upward (in the direction of the arrow 2319 in FIG. 29) as shown in FIG. When the object 2318 is positively charged, it moves in the opposite direction (downward).

In FIG. 29, the first electrode 2313 is disposed above the second electrode 2314 in the vertical direction. Even in this case, even if the direction of the electric field is downward in the vertical direction as shown in FIG. 29, the object moves in the upward direction, which is the opposite direction of gravity.
Note that the arrangement of the pair of electrodes facing each other is not limited to that shown in FIG. 29. For example, the first electrode and the second electrode are each divided into a plurality of electrodes instead of a single electrode. You may arrange | position with a clearance gap provided. Alternatively, the two electrodes may be net-like. In such a case, an object floating in the liquid can be observed from the outside by combining with a transparent substrate.

As the asymmetrical alternating current, the alternating current having the waveform shown in FIG. 7 may be used as in the second embodiment. Even if the waveform is as shown in FIG. 7, the object 2318 floating in the liquid 2312 can be moved in one direction without any adverse effect. Either one of the electrodes only needs to be covered with the insulating film 2316. Even in this case, it is possible to prevent a direct current from flowing between the two electrodes.
What is necessary is just to set the preferable frequency and voltage of asymmetrical alternating current similarly to Embodiment 1. FIG.
In addition, the object 2318 floating in the liquid only needs to be substantially charged. A specific example of the object may be the same as that in the embodiment.

In the case where two electrodes are formed on two opposing substrates as in the present embodiment and the liquid in which the object floats is filled between the two substrates, the movement of the object is as follows. It can also be used like
It is assumed that many objects 2318 are floating in the liquid 2312 and gravity is working downward in FIG. That is, it is assumed that the second substrate 2322 is placed downward. In this case, if an asymmetrical alternating current with an upward unidirectional electric field is applied to the two electrodes 2313 and 2314, gravity is added, so that the object 2318 can be quickly moved to the second substrate 2322 side. That is, the object 2318 can be quickly precipitated.
In addition, if an object 2318 is moved upward by applying an asymmetrical alternating current as shown in FIG. 29 with the unidirectional electric field downward to the two electrodes 2313 and 2314, the object 2318 can be prevented from sinking due to gravity.

By applying an asymmetrical alternating current between the two electrodes 2313 and 2314 using the method or apparatus as described above, the object 2318 floating in the liquid 2312 can be moved in one direction.
In addition, since at least one of the first electrode and the second electrode is covered with an insulating film, a direct current does not flow between the two electrodes. Therefore, the problem that the liquid is electrolyzed or the electrode is corroded by an electrochemical reaction can be reliably prevented. In addition, since at least one of the first electrode and the second electrode is covered with the insulating film, electrons do not reach the second electrode directly from the first electrode, and current does not flow. Therefore, the electric power consumed in this system is only due to charge / discharge of the capacitance formed by the insulating film covering the electrodes. Therefore, the power consumption can be significantly reduced, and the generation of Joule heat can be significantly reduced.
In the case of the fifth embodiment, the waveforms shown in FIGS. 2B and 2C are preferable.

<Embodiment 6>
An electrophoresis apparatus and electrophoresis method according to a sixth embodiment of the present invention will be described with reference to FIG.
FIG. 30 shows a schematic diagram of the electrophoresis apparatus 3100 of the present embodiment.
A first electrode 3113 and a second electrode 3114 are provided on both sides of the container 3123. An AC power source 3215 that generates asymmetrical AC is connected to the first electrode 3113 and the second electrode 3114. An insulating film 3116 is formed over the first electrode 3113 and the second electrode 3114.

When performing electrophoresis, the container 3123 is filled with a predetermined liquid, and an agarose gel 3124 in which a well 3125 is formed is placed in the container 3123. The well 3125 is a hole for injecting a sample.
Next, a sample such as DNA is injected into the well 3125, and asymmetrical alternating current is applied to the first electrode 3113 and the second electrode 3114. As a result, electrophoresis can be performed to move the sample in a certain direction.

  As the liquid, in the conventional electrophoresis, since a direct current flows between the two electrodes, a conductive one is used. However, in this embodiment, the sample having a smaller ion concentration in the liquid is more likely to cause a sample to migrate by generating a unidirectional electric field in the liquid. It is preferable to use it.

As the asymmetrical alternating current applied to the first electrode 3113 and the second electrode 3114, for example, the one shown in FIGS. 2 and 3 may be used. For example, when the asymmetrical alternating current shown in FIG. 2 is applied using the second electrode 3114 as a reference voltage, the direction of the electric field substantially generated in the liquid is rightward (the direction of the arrow 3117 in FIG. 30). Therefore, when the sample in the liquid is negatively charged, the sample moves to the left (the direction of the arrow 3119 in FIG. 30) as shown in FIG. Since the distance traveled through the agarose gel 3124 differs depending on the molecular weight of the sample, the molecules contained in the sample can be separated, and the molecular weight of the sample can be visualized.
Further, as in the second embodiment, the waveform alternating current shown in FIG. 7 may be used for the asymmetrical alternating current. Even with the waveform shown in FIG. 7, electrophoresis can be performed without any particular adverse effect. Note that it is sufficient that either one of the electrodes is covered with the insulating film 3116, and a direct current can be prevented from flowing between the two electrodes.
What is necessary is just to set the preferable frequency and voltage of asymmetrical alternating current similarly to Embodiment 1. FIG.

  In this way, by applying an asymmetrical alternating current to the first electrode 3113 and the second electrode 3114, an electric field is generated substantially in one direction in the liquid, and the sample in the liquid is moved in one direction. Can do.

The step of performing electrophoresis mainly includes the following steps.
(1) preparing an electrophoresis tank including a first electrode 3113 and a second electrode 3114 each at least partially immersed in a liquid, and a sample to be measured;
(2) A step of applying asymmetrical alternating current between the first electrode 3113 and the second electrode 3114 to migrate the sample.

Electrophoresis can be performed by applying an asymmetrical alternating current between the two electrodes 3113 and 3114 using the method or apparatus as described above. In addition, since a substantially unidirectional electric field is applied due to asymmetrical alternating current, the liquid is not electrolyzed and bubbles are not generated and no electrochemical reaction occurs during electrophoresis. Thus, the liquid is not contaminated, and the problem that Joule heat is generated can be avoided. Therefore, it becomes possible to detect the difference in molecular size more accurately.
In the case of the sixth embodiment, the waveforms shown in FIGS. 2B and 2C are preferable.

<Embodiment 7>
An electrophoretic display device according to a seventh embodiment of the present invention will be described with reference to FIG.
FIG. 31 is a schematic cross-sectional view of the electrophoretic display device 4100 of the present embodiment.
A first substrate 4131 and a second substrate 4132 are arranged to face each other. A first electrode (counter electrode) 4113 is formed over the first substrate 4131. A second electrode (pixel electrode) 4114 is formed for each pixel over the second substrate 4132.
An electrophoretic element 4134 is disposed between the first electrode 4113 and the second electrode 4114. The electrophoretic element 4134 includes a circular capsule 4135, a dispersion medium 4136, white electrophoretic particles 4137, and black electrophoretic particles 4138.
A power supply 4115 that generates asymmetrical alternating current is connected to the first electrode 4113 and the second electrode 4114 via a selection transistor 4139.
An adhesive layer 4133 is provided between the second electrode 4114 and the electrophoretic element 4134. Further, the second electrode 4114 is separated for each pixel, and a selection transistor 4139 is connected thereto.

The first substrate 4131 side of the electrophoretic display device 4100 is a display surface. For the first substrate 4131, a transparent substrate such as glass or a transparent film may be used. The second substrate 4132 is not necessarily transparent, and glass, a resin film, or a metal plate with an insulating film formed on the surface may be used.
The first electrode 4113 can be a transparent electrode such as ITO, and may be common to all pixels. As the second electrode, a metal electrode such as Al, Cu, or Au can be used.

  The circular capsule 4135 constituting the electrophoretic element 4134 is made of a transparent resin having a diameter of 20 to 100 μm, for example. A dispersion medium 4136 having a small ion concentration is preferable because a smaller ion concentration easily generates an electric field in one direction in the dispersion medium and causes electrophoresis particles to migrate. For example, alcohols such as ethanol, methanol and IPA, and organic solvents such as benzine and acetone are preferable. When water is used, it is preferable to use pure water, non-ionized water or the like.

  As the two types of electrophoretic particles 4137 and 4138, a black pigment such as carbon black and a white pigment such as titanium dioxide can be used. However, since the two types of electrophoretic particles need to move in opposite directions with respect to a substantially unidirectional electric field generated in the dispersion medium, the two types of electrophoretic particles have substantially opposite polarities. It needs to be charged.

In the operation of the electrophoretic display device 4100, first, a pixel to be displayed in white (or black) is selected by the selection transistor 4139, and then between the second electrode 4114 and the first electrode 4113 in the selected pixel. Apply asymmetrical alternating current.
As a result, in the selected pixel, the white (black) electrophoretic particles 4137 (4138) move, for example, upward, and the black (white) electrophoretic particles 4138 (4137) move downward, resulting in white ( Black) is displayed.

  Conversely, in the case of reverse display, a pixel to be displayed in black (white) is selected by the selection transistor 4319, and an asymmetrical alternating current in which each electrophoretic particle 4137, 4138 moves in the opposite direction is selected in the selected pixel. Application is performed between the second electrode 4114 and the first electrode 4113. Through the above operation, an image can be displayed on the electrophoretic display device 4100.

Further, as in the second embodiment, the asymmetrical alternating current may be the alternating current having the waveform shown in FIG. 2 or FIG. 3 or the alternating current having the waveform shown in FIG.
The preferable frequency of the asymmetrical alternating current varies depending on the type of the dispersion medium 4136. Generally, the dispersion medium with a low ion concentration has a low frequency, and the dispersion medium with a high ion concentration has a high frequency. For example, when pure water is used as the dispersion medium 4136, the frequency may be 500 Hz to 5 MHz. However, when the ion concentration is high due to contamination of the dispersion medium, it is necessary to increase the frequency appropriately.

  In this manner, by applying an asymmetrical alternating current between the first electrode 4113 and the second electrode 4114, an electric field is generated substantially in one direction in the dispersion medium, and the electrophoretic particles in the dispersion medium. Can be moved in one direction and driven as an electrophoretic display device.

  A conventional electrophoretic display device applies a DC voltage between a pixel electrode and a common electrode. At the moment when the DC voltage is applied, the electric field penetrates into the capsule because the electric charge sufficient to cancel the electric field inside the capsule is not induced. For this reason, the electrophoretic particles could be moved a short distance (about the diameter of the capsule). In addition, since the electrophoretic particles once reaching the inside of the capsule are adsorbed on the inner wall of the capsule by electrostatic force, the image was preserved even after the application of voltage was stopped. However, in the conventional apparatus, the driving force for the electrophoretic particles decays rapidly with time, and the movement must be completed before the electrophoretic particles are attenuated. Therefore, the capsule diameter, the type of dispersion medium, and the electrophoretic particle There was a problem that there were restrictions on the types. In addition, when a driving force for larger electrophoretic particles is required, there is a problem that a higher voltage is required.

On the other hand, the electrophoretic display device of the present embodiment continues to move the electrophoretic particles in one direction by applying asymmetrical alternating current between the pixel electrode (second electrode) and the common electrode (first electrode). be able to. Therefore, for example, when displaying in two colors of black and white, an asymmetrical alternating current is applied between the electrodes for a sufficient time according to the capsule, dispersion medium and electrophoretic particles used without increasing the voltage applied to the electrodes. By doing so, the black-and-white conversion of the pixels can be performed more reliably. In addition, since the time for driving the electrophoretic particles can be freely changed, the degree of design freedom such as the size of the pixel, the type of the dispersion medium, and the type of the electrophoretic particles can be expanded.
Also in the case of the seventh embodiment, as the asymmetrical alternating current, the waveforms of FIG. 2B and FIG. 2C are preferable.

<Eighth embodiment>
An electroosmotic flow pump and an operation method thereof according to an eighth embodiment of the present invention will be described with reference to FIG.
FIG. 32 is a schematic cross-sectional view of the electroosmotic flow pump 5100 of the present embodiment.
The inside of the tube 5141 is a flow path and is filled with the liquid 5112 to be conveyed. A first electrode 5113 and a second electrode 5114 provided with a plurality of holes are disposed apart from each other at the upstream portion and the downstream portion of the tube 5141. An AC power supply 5115 that generates asymmetrical AC is connected to the first electrode 5113 and the second electrode 5114.

For the tube 5141, resin, glass, or the like can be used.
The liquid 5112 to be transported is preferably a liquid having a small ion concentration because a liquid having a smaller ion concentration generates a unidirectional electric field in the liquid and easily transports the liquid. For example, alcohols such as ethanol, methanol and IPA, and organic solvents such as benzine and acetone are preferable. When water is used, it is preferable to use pure water, non-ionized water or the like.
When a liquid having a high ion concentration is transported, the electroosmotic pump can be transported indirectly using power.
The first electrode 5113 and the second electrode 5114 are provided with holes having a size of about 0.1 mm to 1 mm so that liquid can pass through.

The asymmetrical alternating current applied to the first electrode 5113 and the second electrode 5114 may be the one shown in FIGS. 2 and 3 as in the above embodiment. For example, when the asymmetrical alternating current shown in FIG. 2 is applied using the second electrode 5114 as a reference voltage, the direction of the electric field substantially generated in the liquid 5112 is rightward (the direction of the arrow 5117 in FIG. 32).
At this time, if the inner wall of the tube 5141 is negatively charged, a positive charge is induced in the liquid 5112 near the inner wall of the tube 5141 as shown in FIG.
In a region farther from the inner wall than the sliding surface 5142 which is a boundary surface between the liquid adhering to the inner wall and the flowing liquid, the liquid 5112 can freely move without adhering to the inner wall of the tube 5141.
In addition, since an electric field substantially in one direction (the direction of the arrow 5117) exists in the liquid 5112, the liquid molecule charged to a positive charge travels toward the second electrode, and the liquid 5112 is transported to the right. The
What is necessary is just to set the preferable frequency and voltage of asymmetrical alternating current similarly to Embodiment 1. FIG.

In this manner, by applying asymmetrical alternating current to the first electrode 5113 and the second electrode 5114, an electric field can be generated in the liquid 5112 substantially in one direction.
In addition, by applying an asymmetrical alternating current as shown in FIG. 32 between the first electrode and the second electrode that are spaced apart from each other in the upstream part and the downstream part in the flow path, The filled liquid 5112 can be transported from the upstream portion to the downstream portion in the flow path.

  In addition, since an asymmetrical alternating current that substantially generates an electric field in one direction is applied, even if the liquid is transported in one direction, the liquid does not electrolyze to generate bubbles, and an electrochemical reaction occurs. And it can prevent that an electrode corrodes. Therefore, since a mechanism for removing bubbles is unnecessary, the structure of the electroosmotic flow pump can be simplified, and the reliability of the electroosmotic flow pump can be increased.

In this embodiment mode, both the first electrode 5113 and the second electrode 5114 are in direct contact with the liquid 5112. Therefore, if a direct current is applied between the two electrodes, a direct current flows. Therefore, the asymmetrical alternating current does not have a substantial direct current component, that is, Veff obtained by integrating the voltage V (t) between the first electrode and the second electrode over one period of the alternating current is substantial. Is preferably 0.
As a result, no net direct current flows between the two electrodes, so that the liquid is not electrolyzed and bubbles are not generated, or the electrode is not corroded without causing an electrochemical reaction. .
In the case of the eighth embodiment as well, in order to efficiently transport the liquid, the asymmetrical alternating current preferably has the waveform shown in FIG. 2 (b) or FIG. 2 (c).

<Embodiment 9>
An electroosmotic flow pump and its operation method according to the ninth embodiment of the present invention will be described with reference to FIG.
The present embodiment is different from the eighth embodiment in that at least one of the first electrode and the second electrode is covered with an insulating film.

FIG. 33 is a schematic cross-sectional view of an electroosmotic flow pump 5200 of the present embodiment.
The inside of the tube 5241 is a flow path and is filled with the liquid 5212 to be conveyed. A first electrode 5213 and a second electrode 5214 provided with a plurality of holes are disposed apart from each other at the upstream portion and the downstream portion of the tube 5241.
The first electrode 5213 and the second electrode 5214 are covered with an insulating film 5216 and connected to an AC power source 5215 that generates asymmetrical AC.
As in the eighth embodiment, the tube 5241 uses resin, glass, or the like, and the liquid 5212 to be transported preferably has a low ion concentration.

The asymmetrical alternating current applied to the first electrode 5213 and the second electrode 5214 may be the one shown in FIGS. 2 and 3 as in the above embodiment. For example, when the asymmetrical alternating current shown in FIG. 2 is applied using the second electrode 5214 as a reference voltage, the direction of the electric field substantially generated in the liquid 5212 is rightward (the direction of the arrow 5217 in FIG. 33).
At this time, when the inner wall of the tube 5241 is negatively charged, a positive charge is induced in the liquid 5212 near the inner wall of the tube 5241. In an area farther from the inner wall than the sliding surface, the liquid 5212 can move freely without being fixed to the inner wall of the tube 5241.
In addition, since there is an electric field in substantially one direction (the direction of the arrow 5217) in the liquid 5212, the liquid 5212 is transported in the right direction. The above operation is the same as in the eighth embodiment.

Further, the asymmetrical alternating current shown in FIG. 7 may be used similarly to the above embodiment. Since the first electrode 5213 and the second electrode 5214 are covered with the insulating film 5216, no direct current flows between the two electrodes. Accordingly, even if the waveform is as shown in FIG. 7, the liquid 5212 can be transported in one direction without any adverse effect. Note that either one of the electrodes need only be covered with the insulating film 5216, and a direct current can be prevented from flowing between the two electrodes.
What is necessary is just to set the preferable frequency and voltage of asymmetrical alternating current similarly to embodiment.

Thus, by applying asymmetrical alternating current to the first electrode 5213 and the second electrode 5214, an electric field can be generated in the liquid 5212 substantially in one direction.
In addition, the liquid 5212 can be transported in one direction by applying an asymmetrical alternating current between the two electrodes 5213 and 5214 using the above-described method or apparatus. In addition, since an asymmetrical alternating current that substantially generates an electric field in one direction is applied, even if the liquid is transported in one direction, the liquid does not electrolyze to generate bubbles, and an electrochemical reaction occurs. Without a problem, it becomes possible to avoid the problem that the electrode corrodes. Therefore, since a mechanism for removing bubbles is unnecessary, the structure of the electroosmotic flow pump can be simplified, and the reliability of the electroosmotic flow pump can be increased.

Furthermore, since at least one of the first electrode and the second electrode is covered with an insulating film, a direct current does not flow between the two electrodes, so that the electrodes can be more reliably prevented from corroding. In addition, since at least one of the first electrode and the second electrode is covered with the insulating film, electrons do not reach the second electrode directly from the first electrode, and current does not flow. Therefore, the electric power consumed in this system is only due to charge / discharge of the capacitance formed by the insulating film covering the electrodes. Therefore, the power consumption can be significantly reduced, and the generation of Joule heat can be significantly reduced.
Also in the case of the ninth embodiment, in order to efficiently transport the liquid, the asymmetrical alternating current preferably has the waveform of FIG. 2B or FIG. 2C.

<Embodiment 10>
Another example of the electroosmotic flow pump according to the tenth embodiment of the present invention will be described with reference to FIG.
The present embodiment is different from the ninth embodiment in that a porous electroosmotic material is provided in the flow path between the first electrode and the second electrode.

FIG. 34 is a schematic cross-sectional view of an electroosmotic flow pump 5300 of the present embodiment.
The inside of the tube 5341 is a flow path and is filled with the liquid 5312 to be conveyed. A first electrode 5313 and a second electrode 5314 provided with a plurality of holes are arranged apart from each other at the upstream portion and the downstream portion of the tube 5341. The first electrode 5313 and the second electrode 5314 are covered with an insulating film 5316, and an AC power supply 5315 that generates asymmetrical AC is connected to the first electrode 5313 and the second electrode 5314.

A porous electroosmotic material 5343 is disposed in the flow path and between the first electrode 5313 and the second electrode 5314.
The electroosmotic material 5343 is a member made of, for example, a silica fiber material or porous ceramic, and plays a role of allowing the liquid to pass through and substantially increasing the area of the inner wall of the flow path.
By arranging this electroosmotic material 5343 as shown in FIG. 34, the electroosmotic material and the liquid come into contact with each other in a minute hole provided inside the electroosmotic material, and the liquid is generated by the action of a unidirectional electric field generated by asymmetrical alternating current. Is transported. Since the porosity inside the electroosmotic material increases the contact area between the electroosmotic material and the liquid, the liquid transport capability also increases.

According to the electroosmotic pump of the present embodiment, as in the ninth embodiment, the liquid is not electrolyzed and bubbles are not generated, and an electrochemical reaction is not caused and the electrode is prevented from corroding. it can.
Therefore, since a mechanism for removing bubbles is not required, the structure of the electroosmotic flow pump can be simplified, and the reliability of the electroosmotic flow pump can be increased.
Further, since at least one of the first electrode and the second electrode is covered with the insulating film, corrosion of the electrode can be prevented more reliably. In addition, the power consumption can be significantly reduced, and the generation of Joule heat can be significantly reduced.
Furthermore, since the electroosmotic effect can be enhanced by disposing a porous electroosmotic material between the first electrode 5313 and the second electrode 5314, the ability of the pump can be dramatically increased. it can.

<Embodiment 11>
A fuel cell according to an eleventh embodiment of the present invention will be described with reference to FIG.
The fuel cell 6100 includes the electroosmotic pump 6151 according to any of the eighth, ninth and tenth embodiments of the present invention. Further, the fuel is transported from the fuel tank 6153 to the fuel battery cell 6152 through the fuel transport pipe 6154.
A fuel cell state sensor 6156 is connected to the fuel cell 6152 and detects the state of the fuel cell.
The state of the fuel cell is transmitted from the fuel cell state sensor 6156 to the fuel supply control circuit 6157, and the fuel supply control circuit 6157 controls the amount of fuel supplied by the fuel cell 6151.
Electric power necessary for the fuel cell state sensor 6156 and the fuel supply control circuit 6157 is supplied by a DC / DC converter 6155 connected to the fuel cell 6152. The DC / DC converter 6155 is connected to a terminal 6158 for supplying power to the outside.

  Since the fuel cell of the present embodiment includes the electroosmotic flow pump of the present invention, the fuel transported by the electroosmotic flow pump is not electrolyzed to generate bubbles, and an electrochemical reaction may occur. There is no corrosion of the electrode. Therefore, a mechanism for removing bubbles is unnecessary, the structure of the fuel cell can be simplified, and the reliability of the fuel cell can be increased.

<Embodiment 12>
A cooling pump according to a twelfth embodiment of the present invention will be described with reference to FIG.
Cooling pump 6200 includes electroosmotic pump 6251 according to any of the eighth, ninth and tenth embodiments of the present invention. Further, the refrigerant is circulated through the refrigerant transport pipe 6263 through the heat receiving unit 6259 and the heat exchanger 6260.
The heat receiving unit 6259 is provided with a temperature sensor 6261 and transmits the temperature of the heat receiving unit 6259 to the pump control circuit 6262. The pump control circuit 6262 controls the electroosmotic pump 6251 based on information from the temperature sensor 6261, moves the refrigerant, and keeps the temperature of the heat receiving unit 6259 at an appropriate level.

  Since the cooling pump of the present embodiment includes the electroosmotic flow pump of the present invention, the refrigerant moved by the electroosmotic flow pump is not electrolyzed to generate bubbles, and an electrochemical reaction may occur. Neither does the electrode corrode. Therefore, since a mechanism for removing bubbles is not necessary, the structure of the cooling pump can be simplified, and the reliability of the cooling pump can be increased.

<Embodiment 13>
A chemical supply apparatus 6300 according to a thirteenth embodiment of the present invention will be described with reference to FIG.
The chemical solution supply apparatus 6300 includes the electroosmotic pump 6351 according to any of the eighth, ninth, and tenth embodiments of the present invention. Further, the chemical solution is transported from the chemical solution tank 6364 to the chemical solution supply destination through the chemical solution transport pipe 6368.
A flow rate sensor 6365 is provided in the middle of the chemical solution transport pipe 6368, and flow rate information is transmitted to the chemical solution supply control circuit 6366. The chemical supply control circuit 6366 controls the electroosmotic pump 6351 based on the instruction transmitted in advance from the chemical supply program input device 6367 and the flow rate information transmitted from the flow sensor 6365, and adjusts the flow rate of the chemical to be transported. .

  Since the chemical solution supply apparatus of the present embodiment includes the electroosmotic flow pump of the present invention, the chemical solution transported by the electroosmotic flow pump is not electrolyzed to generate bubbles, and an electrochemical reaction occurs. Neither does the electrode corrode. Therefore, since a mechanism for removing bubbles is not necessary, the structure of the chemical liquid supply apparatus can be simplified, and the reliability of the chemical liquid supply apparatus can be increased.

1110 Electric field generator 1111 Container 1112 Liquid 1113 First electrode 1114 Second electrode 1115 AC power source 1216 Insulating film 2100 Floating body moving device 2111 Container 2112 Liquid 2113 First electrode 2114 Second electrode 2115 AC power source 2118 Object 2216 Insulation Membrane 3100 Electrophoresis device 3124 Agarose gel 3125 Well 4100 Electrophoretic display device 4131 First substrate 4132 Second substrate 4134 Electrophoretic element 4135 Capsule 4136 Dispersion medium 4137 Electrophoretic particles 4138 Electrophoretic particles 4139 Select transistor 5100 Electroosmotic flow pump 5141 Tube 5142 Sliding surface 5216 Insulating film 5343 Electroosmotic material 6100 Fuel cell 6151 Electroosmotic flow pump 6152 Fuel cell 6153 Fuel tank 6154 Fuel Transport pipe 6155 DC / DC converter 6156 Fuel cell state sensor 6157 Fuel supply control circuit 6158 Power supply terminal 6200 Cooling pump 6251 Electroosmotic flow pump 6263 Refrigerant transport pipe 6300 Chemical liquid supply device 6351 Electroosmotic flow pump 6368 Chemical liquid transport pipe

Claims (27)

A container filled with liquid;
A first electrode and a second electrode arranged at a predetermined interval so that at least a part of the liquid is injected into the container;
An alternating current generator connected to the first electrode and the second electrode and applying an asymmetrical alternating current between the two electrodes;
The AC generator has either an electric field in the liquid that is substantially from the first electrode to the second electrode, or an electric field that is substantially from the second electrode to the first electrode. An electric field generator characterized by generating The electric field generator according to claim 1,
The first electrode and the second electrode are disposed so as to be in direct contact with the liquid injected into the container,
The asymmetrical alternating current is obtained by integrating the voltage V (t) (t is time) between the first electrode and the second electrode over one period of alternating current Veff = ｅV (t) dt
Is substantially 0 and has no substantial DC component. The electric field generator according to claim 1,
An electric field generation device characterized in that at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid. A container filled with a liquid in which an object floats;
A first electrode and a second electrode arranged at a predetermined interval so that at least a part of the liquid is injected into the container;
An alternating current generator connected to the first electrode and the second electrode and applying an asymmetrical alternating current between the two electrodes;
Due to the asymmetrical alternating current applied by the alternating current generator, movement of the object floating in the liquid from the first electrode to the second electrode, or movement from the second electrode to the first electrode is performed. A floating body moving device characterized by moving either one of them. The floating body moving device according to claim 4,
The first electrode and the second electrode are both arranged so as to be in direct contact with the liquid,
The asymmetrical alternating current is obtained by integrating the voltage V (t) (t is time) between the first electrode and the second electrode over one period of alternating current Veff = ｅV (t) dt
Is substantially 0, and has no substantial DC component. The floating body moving device according to claim 4,
A floating body moving device, wherein at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with a liquid. An electrophoresis tank into which a liquid containing a sample is injected;
A first electrode and a second electrode disposed at a predetermined interval so that at least a part of the liquid is injected into the electrophoresis tank;
An alternating current generator connected to the first electrode and the second electrode and applying an asymmetrical alternating current between the two electrodes;
The asymmetrical alternating current applied by the alternating current generator causes the sample contained in the liquid to migrate between the first electrode and the second electrode in the liquid,
An electrophoretic device, wherein at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid. A first electrode and a second electrode arranged to face each other at a predetermined interval;
An electrophoretic element that is disposed in a space sandwiched between the first electrode and the second electrode and includes a plurality of capsules including electrophoretic particles and a dispersion;
An AC generator connected to the first electrode and the second electrode and applying an asymmetrical alternating current between the two electrodes;
An electrophoretic display device, wherein the electrophoretic particles in each capsule are moved in the direction of one electrode by the asymmetrical alternating current. A flow path for flowing liquid;
A first electrode and a second electrode which are spaced apart from each other in an upstream portion and a downstream portion of the flow path and have a plurality of holes;
An alternating current generator connected to the first electrode and the second electrode, and applying an asymmetrical alternating current between the two electrodes;
By applying the asymmetrical alternating current, the liquid that has flowed into the flow channel is transported from the first electrode in the upstream portion to the second electrode in the downstream portion in the flow channel. And electroosmotic flow pump. The electroosmotic pump according to claim 9,
The first electrode and the second electrode are arranged so as to be in direct contact with the liquid flowing into the flow path,
The asymmetrical alternating current is obtained by integrating the voltage V (t) (t is time) between the first electrode and the second electrode over one period of alternating current Veff = ｅV (t) dt
The electroosmotic flow pump is characterized in that is substantially zero and has no substantial DC component. The electroosmotic pump according to claim 9 or 10,
An electroosmotic pump characterized in that at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid. The electroosmotic pump according to any one of claims 9, 10 or 11,
An electroosmotic pump, wherein a porous electroosmotic material is provided in the flow path between the first electrode and the second electrode. A fuel cell comprising the electroosmotic pump according to any one of claims 9 to 12. A cooling pump driven by the electroosmotic pump according to any one of claims 9 to 12. A chemical supply apparatus driven by the electroosmotic pump according to any one of claims 9 to 12. A preparatory step of injecting liquid into the container;
An arrangement step of arranging the first electrode and the second electrode at predetermined intervals so that at least a part of each is immersed in the liquid;
An asymmetrical alternating current is applied between the first electrode and the second electrode, and an electric field that substantially flows from the first electrode to the second electrode in the liquid, or substantially the second electrode And an electric field generating step of generating any one of the electric fields from the first electrode to the first electrode. The electric field generation method according to claim 16,
The first electrode and the second electrode are both arranged so as to be in direct contact with the liquid,
The asymmetrical alternating current is obtained by integrating the voltage V (t) (t is time) between the first electrode and the second electrode over one period of alternating current Veff = ｅV (t) dt
Is substantially zero and does not have a substantial direct current component. The electric field generation method according to claim 16,
An electric field generating method, wherein at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid. The electric field generation method according to claim 16,
The method for generating an electric field, wherein the asymmetrical alternating current is a rectangular wave having a high potential duration and a low potential duration. The electric field generation method according to claim 16,
The electric field generating method according to claim 1, wherein the asymmetrical alternating current is a triangular wave or a sawtooth wave having different rise times and fall times. A preparatory step for injecting a liquid into which the object floats;
An arrangement step of arranging the first electrode and the second electrode at a predetermined interval so that at least a part of each of the first electrode and the second electrode is immersed in the liquid;
Asymmetrical alternating current is applied between the first electrode and the second electrode, and the object floating in the liquid moves from the first electrode to the second electrode, or the second electrode A floating body moving method comprising a moving step of moving any one of the movements from to the first electrode. The floating body moving method according to claim 21,
The first electrode and the second electrode are both arranged so as to be in direct contact with the liquid,
The asymmetrical alternating current is obtained by integrating the voltage V (t) (t is time) between the first electrode and the second electrode over one period of alternating current Veff = ｅV (t) dt
Is substantially zero and has no substantial direct current component. The floating body moving method according to claim 21,
A floating body moving method, wherein at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with a liquid. A preparatory step of injecting a liquid containing a sample to be moved by electrophoresis into the electrophoresis tank;
An arrangement step of arranging the first electrode and the second electrode at predetermined intervals so that at least a part of each of the first electrode and the second electrode is immersed in the liquid;
Applying an asymmetrical alternating current between the first electrode and the second electrode to cause the sample to migrate between the first electrode and the second electrode in a liquid,
An electrophoresis method, wherein at least one of the first electrode and the second electrode is covered with an insulating film and is not in direct contact with the liquid. The first electrode and the second electrode are spaced apart from each other in the upstream portion and the downstream portion in the flow path of the electroosmotic flow pump,
Applying an asymmetrical alternating current between the first electrode and the second electrode;
A method of operating an electroosmotic pump characterized by transporting the liquid that has flowed into the flow path from the first electrode in the upstream portion toward the second electrode in the downstream portion in the flow path . A method of operating an electroosmotic pump according to claim 25,
The first electrode and the second electrode are both arranged so as to be in direct contact with the liquid,
The asymmetrical alternating current is obtained by integrating the voltage V (t) (t is time) between the first electrode and the second electrode over one period of alternating current Veff = ｅV (t) dt
Is substantially zero and does not have a substantial direct current component. A method of operating an electroosmotic pump according to claim 25,
A method for operating an electroosmotic pump, wherein at least one of the first electrode and the second electrode is covered with an insulating film and does not directly contact a liquid.

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