KR101905139B1 - Method and apparatus for controlling actuation of liquid using electrowetting phenomenon - Google Patents

Abstract

The present invention relates to a liquid behavior control apparatus and method that can more effectively control wettability, hydrophilicity, or shape of an electrolyte liquid by reversibly / irreversibly using electrowetting phenomenon. The liquid behavior control device includes: a first electrode; A second electrode comprising a graphene layer formed on the metal mesh; And voltage applying means for applying a voltage between the first electrode and the second electrode, and the electric field formed by the applied voltage is adjusted to adjust the wettability, hydrophilicity or shape of the liquid on the second electrode .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and a method for controlling a liquid behavior using an electrowetting phenomenon,

The present invention relates to a liquid behavior control apparatus and method that can more effectively control wettability, hydrophilicity, or shape of an electrolyte liquid by reversibly / irreversibly using electrowetting phenomenon.

Electrowetting phenomenon refers to a phenomenon in which the contact angle between an electrolyte solution and a base layer such as an electrode layer or an insulating layer changes under the action of an electric field. That is, the phenomenon that the electrolyte solution shrinks or expands on the surface of the base layer under the action of an electric field, and the degree of wettability, hydrophilicity or surface shape of the electrolyte solution changes.

Such electrowetting phenomenon is expected to be applicable to various fields and applications such as a water treatment substrate, an electrowetting display device, a thickness regulating fluid lens, an electronic paper, a pixel based on electrowetting, a colored pixel, .

In addition, the electrowetting display device refers to a device for displaying by controlling the expansion or contraction of the oil ink by means of an electrode by means of electrowetting phenomenon. The electrowetting display device is suitable for a bistable state display, good reflectance, low power consumption, (See Korean Patent Application No. 2012-7030792, etc.).

Due to the wide applicability of such electrowetting phenomenon, studies have been made on an apparatus and method for controlling liquid behavior using such electrowetting phenomenon. However, until now, devices and methods capable of effectively controlling the behavior and shape of a liquid Is not developed properly.

As one of such prior arts, Lippmann has proposed an electrocapillary phenomenon in which a hydrophilic liquid droplet is brought into contact with a metal electrode and the capillary force of the droplet and the metal surface is changed by external electrostatic charge. However, the flow field control method using the electro-capillary phenomenon has a disadvantage in that electricity can flow through the fluid and the surface state of the metal electrode changes due to the electrochemical reaction, so that the electrode can be corroded or oxidized.

As another example of the prior art for solving this problem, Korean Patent Registration No. 0781739 discloses a droplet control device and method in which an insulator is formed on an electrode and a voltage is applied to the hydrophilic droplet on the insulator to change the behavior or contact angle of the droplet Etc. have been proposed. However, in such a droplet control apparatus and method, it is also necessary to change the behavior and the contact angle of the droplet in a state in which the droplet is directly connected / contacted to the electrode. Therefore, there is still a possibility that an electrical short may occur in the process of changing the behavior or the contact angle of the liquid droplet in spite of the formation of the insulator.

In addition, in the conventional liquid droplet control apparatus and method, only the passive control that changes the behavior or the contact angle of the droplet is possible according to the physical and chemical properties of the hydrophilic liquid itself. Specifically, according to the conventional droplet control device method, the behavior of the droplet or the like depending on the easily adjustable control condition, for example, the distance between the electrodes, the usage amount of the hydrophilic droplet, the application amount of the voltage, It is impossible to perform active control for controlling the degree of change of the contact angle. Therefore, it is a fact that application of the control such as the behavior of the droplet using the electrowetting phenomenon is limited in practical industrial application.

Accordingly, there is a continuing need to develop a liquid behavior control apparatus and method capable of reversibly / irreversibly controlling the wettability, hydrophilicity, or shape of an electrolyte liquid using electro-wetting phenomenon.

The present invention provides a liquid behavior control device and method that can more effectively control the behavior or shape of the electrolyte liquid such as wettability or hydrophilicity, reversibly / irreversibly, by using electro-wetting phenomenon.

The present invention relates to a plasma display panel comprising a first electrode;

A second electrode comprising a graphene layer formed on the metal mesh;

And voltage applying means for applying a voltage between the first electrode and the second electrode,

A liquid behavior control device using an electrowetting phenomenon that regulates the electric field formed by the applied voltage to control the wettability, hydrophilicity, or shape of the liquid on the second electrode.

The present invention also provides a method of manufacturing a liquid electrolyte, comprising: a first step of applying a droplet of an electrolyte liquid onto the second electrode; And a second step of applying a voltage between the first electrode and the second electrode to change a wettability, a hydrophilicity or a shape of the liquid droplet, thereby controlling the liquid behavior control using the liquid behavior control device of the present invention.

According to the present invention, it is possible to prevent corrosion or oxidation of the second electrode in which the liquid is located in the process of controlling the liquid behavior by the electro-wetting phenomenon, impart properties such as dustproof / waterproof, It is possible to suppress the occurrence of an electrical short circuit or the like.

In addition, according to the present invention, it is possible to perform active control that adjusts the behavior of the droplet or the degree of change of the contact angle by adjusting the control condition that can be easily adjusted by the user in the liquid behavior control process, / Irreversible control is also possible. In addition, it is possible to control the behavior or the contact angle of a very small amount of liquid droplet, as well as control under a relatively low current / output.

Therefore, by applying the liquid behavior control apparatus and method of the present invention, it is possible to very effectively control the behavior and shape such as wettability or hydrophilicity of the electrolyte / hydrophilic liquid by using electro-wetting phenomenon, .

Therefore, such a liquid behavior control device and method can be effectively applied to various fields and applications such as a water treatment substrate, an electrowetting display device, a thickness regulating fluid lens, an electronic paper, pixels based on electrowetting, a colored pixel .

1 is a schematic diagram schematically showing an example of a liquid behavior control apparatus according to an embodiment of the present invention.
FIG. 2 is a photograph showing that the shape of a liquid changes according to a voltage / electric field control by applying the liquid behavior control device according to an embodiment of the present invention.
FIGS. 3 and 4 are diagrams illustrating a method of controlling a liquid state according to an embodiment of the present invention by applying the voltage to change the shape of the liquid, and then decreasing or stopping the application of the voltage Is a photograph showing an example of an irreversible control method in which the shape of the liquid is not restored again.
FIGS. 5 and 6 are diagrams illustrating a method of controlling a liquid shape according to an exemplary embodiment of the present invention. Referring to FIG. 5 and FIG. 6, And the shape of the liquid is recovered again.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid behavior control apparatus and method according to a specific embodiment of the present invention will be described in detail with reference to the accompanying drawings.

According to an embodiment of the present invention, there is provided a plasma display panel comprising: a first electrode;

A second electrode comprising a graphene layer formed on the metal mesh;

And voltage applying means for applying a voltage between the first electrode and the second electrode,

There is provided an apparatus for controlling a liquid behavior using an electrowetting phenomenon which regulates the electric field formed by the applied voltage to control the wettability, hydrophilicity or shape of the liquid on the second electrode.

FIG. 1 schematically shows an example of a liquid behavior control apparatus according to an embodiment of the present invention.

The liquid behavior control device of one embodiment controls the electric field by the voltage applied between the first and second electrodes to control the behavior such as the wettability or the hydrophilicity of the liquid on the second electrode or the electric wetting phenomenon Corresponds to a liquid behavior control device. In particular, the liquid behavior control apparatus according to an embodiment can position liquid droplets or the like on a second electrode including a graphene layer formed on a metal mesh to change the contact angle thereof, thereby controlling the behavior or shape of the liquid.

The graphene contained in the second electrode is one of carbon isotopes made of carbon atoms. Generally, graphene can refer to a two-dimensional single sheet consisting of sp 2 of carbon or a laminate sheet having a nanoscale thickness of several to several tens of single sheets stacked. Graphene has a wide surface area and excellent mechanical, thermal and electrical properties compared to other nano additives (Na-MMT, LDH, CNT, CNF, EG etc.) and has flexibility and transparency .

In the liquid behavior control device of one embodiment, the graphene layer is formed on the second electrode, the second electrode is provided with properties such as waterproof or dustproof, and the surface of the metal mesh of the second electrode is electrochemically reacted Or the second electrode can be prevented from being corroded or oxidized. That is, the graphene layer acts as a corrosion or oxidation inhibiting layer of the metal mesh, and it is possible to effectively inhibit the metal mesh from being corroded or oxidized in the process of controlling the liquid behavior by the electric wetting phenomenon.

Further, by forming the graphene layer that protects the second electrode, even if the liquid droplet is placed on the second electrode to control the movement or the contact angle of the liquid (liquid), there is a possibility that electrical short- None were identified.

In addition, in the liquid behavior control device of the embodiment, a graphene layer having excellent electrical characteristics is formed on the second electrode, and a droplet or the like is positioned on the graphene layer, and the contact angle or the behavior thereof is changed and controlled . Accordingly, the user can easily and easily adjust the controllable conditions, for example, the distance between the electrodes, the amount of the droplet to be used, the amount of the applied voltage or the position of the electrode / droplet to be added (for example, (Or on the upper side or the lower side) of the liquid droplet to adjust the degree of change of the liquid droplet or the contact angle. As will be described in more detail below, when the liquid behavior control apparatus of one embodiment is applied, the active control of the liquid behavior, which has not been possible in the prior art, can be achieved by controlling the reversible / irreversible control of the liquid behavior .

In addition, when the liquid behavior control device of the embodiment is applied, the droplet of a very small amount (for example, about 5 mL) due to the excellent electrical characteristics of the second electrode, such as the graphene layer, Or the contact angle can be controlled, and it has been confirmed that control of the behavior / contact angle of the liquid can be performed under a relatively low current / output.

Therefore, by applying the liquid behavior control device of one embodiment, the behavior or shape of the electrolyte / hydrophilic liquid such as wettability or hydrophilicity of the electrolyte / hydrophilic liquid can be controlled very effectively using active wetting phenomenon, and active control thereof becomes possible, It is possible to provide a footrest that can be applied.

On the other hand, in the liquid behavior control apparatus of this embodiment, the first electrode may be an electrode including any conductive material. In a specific example, the first electrode is a conductive metal selected from the group consisting of nickel, iron, copper, and alloys thereof; Or a carbon-based conductive material selected from the group consisting of graphite, graphene, carbon, and derivatives thereof. In addition, an electrode including any conductive material may be used without limitation.

In addition, the metal mesh included in the second electrode may be made of a conductive metal, and may be any conductive metal mesh layer formed in a network, and the kind of the conductive metal included therein is not particularly limited, , Copper, and alloys thereof.

The metal mesh-like graphene layer may be grown and formed on the metal mesh by chemical vapor deposition, and may have a nanoscale thickness, for example, 1 to 500 nm, or 10 to 100 nm . In a more specific example, the graphene layer is supplied at a temperature of 1000 占 폚 or higher, for example, 1000 占 폚 to 1500 占 폚, while supplying hydrogen gas and a carbon source gas onto the metal mesh under the supply of an inert gas such as argon gas, And may be formed to have a desired thickness according to the control of growth conditions such as time during the course of the chemical vapor deposition.

In the most specific example, the metal mesh sample is heated from about 1000 sccm to about 1000 ° C, and when it reaches 1000 ° C, the metal mesh surface is heat treated for a period of time (eg, about 10 minutes) Clean, and remove the oxide layer. The graphene can then be grown for a period of time (e.g., about 10 minutes) by reducing the injection amount of argon gas while injecting a mixed gas of hydrogen gas and a carbon source gas (e.g., methane gas). Finally, the injection of hydrogen and carbon source gas can be stopped, and the argon gas can be transferred to another quartz tube while it is flowing and the process can be completed by rapidly cooling in air. In the above-described method, a second electrode can be obtained by forming a graphene layer on a metal mesh.

Meanwhile, the liquid behavior control apparatus according to an embodiment may include a voltage application unit that uses the first electrode as an anode and the second electrode including a graphene layer as a negative electrode, and connects them. Such a voltage applying means can be any voltage applying means which is commonly used, so that further description thereof will be omitted.

The droplet of the electrolyte and / or the hydrophilic liquid to be controlled in its behavior or shape is placed on the graphene layer of the second electrode of the liquid behavior control device of this embodiment, The contact angle of the liquid droplet can be changed by applying and controlling a voltage / electric field between the liquid droplet and the liquid, thereby controlling the wettability or hydrophilic behavior or shape of the liquid droplet. 2 shows an example in which the shape of the liquid changes and the behavior of the liquid is controlled by changing the contact angle of the liquid by adjusting the voltage / electric field to 0 kV, 1 kV, 2 kV, 3 kV and 4 kV by applying the liquid behavior control device Respectively.

The liquid behavior control method using the liquid behavior control device includes a first step of applying a droplet of an electrolyte (and / or a hydrophilic) liquid onto the second electrode; And a second step of applying a voltage between the first electrode and the second electrode to change the wettability, hydrophilicity or shape of the droplet.

As already described above, by applying such a liquid behavior control apparatus and method, it is possible to control the liquid behavior by electro wetting phenomenon very effectively without corrosion or oxidation of the second electrode, Has been confirmed.

Meanwhile, according to one example of the liquid behavior control method, the second step is a step of applying the voltage / electric field to change the wettability, hydrophilicity or shape of the droplet, and then reducing or stopping the application of the voltage The wettability, hydrophilicity or shape of the droplet may be irreversible control step that is not restored again. One example of this irreversible control step is shown in Figures 3 and 4.

For this irreversible control, in the liquid behavior control method, the distance between the electrodes, the amount of the droplet to be used, the amount of the voltage to be applied, or the position to which the electrode / droplet is added can be adjusted. According to an example, as shown in FIGS. 3 and 4, the behavior of the liquid may be controlled with the second electrode and the droplet on the second electrode positioned above the first electrode, The control may be carried out with the voltage higher than the voltage, or the distance between the electrodes may be made closer to each other, thereby performing the irreversible control.

At this time, the interelectrode distance or the threshold voltage required for the irreversible control may be different depending on the type of the liquid to be subjected to the behavior control, and this can be determined by a person skilled in the art.

According to another example of the liquid behavior control method, in the second step, after the voltage is applied to change the wettability, hydrophilicity, or shape of the liquid droplet, the application of the voltage is decreased or stopped to change the wettability, Or a reversible control step of recovering the shape again. Examples of such reversible control steps are shown in Figures 5 and 6.

In this reversible control, the distance between the electrodes, the amount of the droplet to be used, the amount of the voltage to be applied, or the position of the electrode / droplet to be added can be adjusted. According to a specific example, as shown in FIGS. 5 and 6, the behavior of the liquid may be controlled by placing the second electrode and the droplet on the second electrode under the first electrode, The reversible control can be performed by controlling the voltage while maintaining the voltage lower than the threshold voltage, or by making the distance between the electrodes relatively long.

At this time, the interelectrode distance or the applied voltage necessary for the reversible control may be different depending on the type of the liquid to be subjected to the behavior control, and it can be determined by a person skilled in the art.

As described above, by applying the liquid behavior control apparatus and method according to the embodiments of the present invention, it is possible to effectively protect the second electrode, and to suppress electrical short-circuit in the control process. In addition, since active control of liquid behavior, for example, reversible / irreversible control, becomes possible, it is possible to very effectively control the behavior or shape of the electrolyte / hydrophilic liquid such as wettability or hydrophilicity have.

Therefore, such a liquid behavior control device and method can be effectively applied to various fields and applications such as a water treatment substrate, an electrowetting display device, a thickness regulating fluid lens, an electronic paper, pixels based on electrowetting, a colored pixel .

Claims (10)

A first electrode;
A second electrode comprising a graphene layer formed on the metal mesh;
And voltage applying means for applying a voltage between the first electrode and the second electrode,
Wherein the metal mesh is formed of a conductive metal selected from the group consisting of nickel, aluminum, iron, copper, and alloys thereof,
And controlling the electric field formed by the applied voltage to adjust the wettability, hydrophilicity, or shape of the liquid on the graphene layer included in the second electrode.
The method of claim 1, wherein the first electrode is a conductive metal selected from the group consisting of nickel, iron, copper, and alloys thereof; or
A carbon-based conductive material selected from the group consisting of graphite, graphene, carbon, and derivatives thereof.
delete The liquid behavior control apparatus according to claim 1, wherein the graphene layer is grown and formed on the metal mesh by chemical vapor deposition.
5. The liquid behavior control apparatus according to claim 4, wherein the graphene layer is formed by chemical vapor deposition at a temperature of 1000 占 폚 or higher while supplying hydrogen gas and a carbon source gas onto a metal mesh under the supply of an inert gas.
2. The liquid behavior control apparatus according to claim 1, wherein the graphene layer has a thickness of 1 to 500 nm.
The liquid behavior control apparatus according to claim 1, wherein the first electrode is a positive electrode and the second electrode is a negative electrode.
A first step of applying a droplet of the electrolyte liquid onto the graphene layer included in the second electrode; And
And a second step of applying a voltage between the first electrode and the second electrode to change the wettability, hydrophilicity or shape of the liquid droplet.
9. The method of claim 8, wherein the second step comprises applying the voltage to change the wettability, hydrophilicity or shape of the droplet, and then reducing or stopping the application of the voltage to regain the wettability, Wherein the liquid is a liquid.
9. The method of claim 8, wherein the second step further comprises applying the voltage to vary the wettability, hydrophilicity, or shape of the droplet, and then reducing or stopping the application of the voltage, A liquid behavior control method as an irreversible control step that is not restored.

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