KR20200082902A - Micro pyramidal nozzle array and electrostatic spray system comprising the same - Google Patents

Abstract

The present invention relates to a micro nozzle array comprising: a base layer including at least one or more holes; and at least one or more micro nozzles each enclosing the at least one or more holes from the base layer, and protruding from a region having a predetermined thickness, wherein the thickness becomes thinner in a direction protruding from a portion in contact with the base layer.

Description

Micro-pyramidal nozzle array and electrostatic spray system comprising the same

It relates to a micro-nozzle array and an electrostatic spraying system comprising the same.

The present invention is a technology in the field of indoor air cleaning and humidification, and is specifically used directly in a corresponding product to deal with a technique of spraying and controlling water droplets using electrostatic spraying. Unlike the filter type air cleaning system that is widely used in industry, the present invention is applied to an electrostatic spray air cleaning humidification system capable of sterilizing fine dust dust and airborne bacteria in the air by using charged water droplet characteristics. Since the electrostatic spray air cleaning humidification system does not use a filter, it has the advantage of efficient air cleaning without problems such as periodic replacement, noise, energy loss, and generation of secondary harmful substances, but it is difficult to spray water electrostatically and stable power failure of the nozzle array Due to difficulty in spraying and difficulty in controlling water droplets, it was difficult to effectively implement it with a commercial air cleaning system.

Since water (based on deionized water) has higher electrical conductivity (120 μS/m and surface tension (0.072 N/m)) than other fluids, it is possible to obtain a stable electrostatic spray phenomenon under very limited conditions in a typical spray nozzle. Even if it is a stable electrostatic spray phenomenon, it is highly likely to form an unstable form with discharge.It is known that a stable electrostatic spray requires a nozzle of a non-conductive/hydrophobic material with a diameter of several tens of micrometers. It is very difficult and there is a problem that the amount of droplets to be sprayed is rapidly reduced.

In order to solve the low flow problem of electrostatic spraying, approaches (arrays) in which a number of fine nozzles are continuously arranged can be confirmed through several research cases. In the case of the electrostatic spray of the array type, it is very important to uniformly form the electric field at each end of each nozzle, but for this, a nozzle manufactured with high precision is required, and the arrangement and applied voltage of the placed electrode must also be carefully considered, so it is practical Very few successful cases. In addition, the nozzle array used in most of the existing studies is manufactured through a one-time process such as photolithography, dry etching, and laser processing, so efficiency is very low.

On the other hand, in relation to the electrostatic spray nozzle and its manufacturing method, Korean Patent Registration No. 10-1822927 discloses a micro nozzle array, an air cleaning device using the manufacturing method and a micro nozzle array, and a micro nozzle formed by protruding in a cylindrical shape Disclosed is a micro nozzle array comprising a.

Korean Registered Patent No. 10-1822927

An object of one aspect of the present invention is to provide a micro-nozzle array capable of supplementing various disadvantages of the micro-nozzle array, which is a core component of electrostatic spraying, and enabling efficient electrostatic spraying.

An object of another aspect of the present invention is to provide a mold-based manufacturing process for mass-producing a micro-nozzle array, which is a core component of electrostatic spraying, with high yield.

In order to achieve the above object, in one aspect of the present invention

A base layer comprising at least one hole; And

At least one micro-nozzle surrounding each of the at least one hole from the base layer and protruding a region of a predetermined thickness, wherein the thickness becomes thinner in a direction protruding from a portion in contact with the base layer; A micro-nozzle array is provided.

In addition, in another aspect of the present invention

a) performing anisotropic etching on the substrate to form a shape corresponding to the micro nozzle of the micro nozzle array;

b) after depositing the photoresist on the substrate, patterning the photoresist so that a hole in the micro nozzle is formed;

c) preparing a master by filling a metal with the photosensitive agent patterned on the substrate;

d) filling the master with metal to prepare a metal mold;

e) filling the metal mold with a polymer to produce a micro-nozzle array; a method for manufacturing a micro-nozzle array is provided.

Furthermore, in another aspect of the present invention

Fluid supply; Power supply; Electrostatic spray droplet generation unit; And an electrostatic spray system including a counter electrode, wherein the electrostatic spray droplet generating unit includes the micro nozzle array.

Furthermore, in another aspect of the present invention

Fluid supply; Power supply; Electrostatic spray droplet generation unit; And an electrostatic spraying system including a counter electrode, wherein the electrostatic spray droplet generating unit includes the micro-nozzle array, and a humidifying sterilizer including the electrostatic spraying system.

The micro-nozzle array provided in one aspect of the present invention has a small-sized pyramid-shaped nozzle, so stable and efficient electrostatic spraying is possible regardless of the electric field crosstalk problem that has been problematic in the existing array system.

In addition, the manufacturing method of the micro-nozzle array provided in another aspect of the present invention is capable of mass-production of the electrostatic spray material by presenting a metal mold-based process that can easily manufacture an ultra-small pyramid nozzle array.

1 is a schematic view showing the principle of electrostatic spraying;
2 is a schematic view showing the structure of a micro nozzle array according to an embodiment of the present invention;
3 is a schematic view showing a method of manufacturing a micro-nozzle array according to an embodiment of the present invention;
4 is a photograph observed by an electron scanning microscope (SEM) of a micro nozzle array according to an embodiment of the present invention;
5 is a schematic view showing an electrostatic spraying system according to an embodiment of the present invention;
6 is a schematic view showing an electrostatic spray droplet generation unit of an electrostatic spray system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the contents described in the accompanying drawings. However, the present invention is not limited or limited by the exemplary embodiments. The same reference numerals in each drawing denote members that perform substantially the same function.

The objects and effects of the present invention may be naturally understood or more apparent by the following description, and the objects and effects of the present invention are not limited only by the following description. In addition, in the description of the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

In one aspect of the invention

A base layer 110 including at least one hole; And

At least one micro nozzle that surrounds the at least one or more holes from the base layer and is formed by protruding an area of a predetermined thickness, and is gradually thinner in a direction protruding from a portion in contact with the base layer ( 120); is provided.

Hereinafter, the micro-nozzle array 100 provided in one aspect of the present invention will be described in detail.

First, the principle of electrostatic spraying as shown in FIG. 1 will be described. Electrostatic spraying is a technology that applies a high electric field to a liquid supplied to a fine nozzle to atomize the liquid using the surface change characteristics of the liquid. The electrostatic spray has various spray characteristics depending on the applied voltage, flow rate, surface tension of the liquid, electrical conductivity, supply flow rate, etc. Among them, the Cone jet mode electrostatic spray capable of stably spraying fine droplets is most used. Cone jet mode electrostatic spray is tens to hundreds of times smaller than the spray nozzle size through the primary atomization by the Taylor cone end jet created through the interaction of the surface tension of the liquid with external electric force, and the secondary atomization due to the Rayleigh splitting phenomenon. Fine droplets can be produced. Therefore, if a nozzle with a size of several tens of micrometers is used, droplets having a size of hundreds of nanometers can be obtained. Due to the electrostatic spraying characteristics, as the diameter of the nozzle decreases, the onset voltage of the electro-ejection spray decreases. More stable spraying is possible than using a micro-nozzle array of paper cone shape.

2 is a schematic view showing an example of a micro-nozzle array 100 provided in one aspect of the present invention.

Referring to FIG. 2, the micro-nozzle array 100 provided in one aspect of the present invention may include a base layer 110 and at least one micro-nozzle 120. In addition, the micro-nozzle array 100 may further include a plurality of pillars 130.

The base layer 110 is formed with a plurality of holes (holes). In addition, a plurality of micro nozzles 120 may be protruded on the base layer. The plurality of holes formed in the base layer may be connected to the holes formed in the plurality of micro nozzles. That is, the fluid supplied from one surface of the base layer may be discharged to the other surface of the base layer through a plurality of holes in the base layer and through a plurality of micro nozzles.

In addition, the at least one micro-nozzle 120 may be formed by protruding an area of a predetermined predetermined thickness surrounding each of the plurality of holes from the base layer 110. The plurality of micro nozzles may be arranged in a matrix form and protrude from the base layer. The micro-nozzle is advantageous not only for protruding the droplets by protruding from the base layer, but also for stably spraying the droplets. For example, when using a base layer provided with a plurality of micro-nozzles, droplets can be formed smaller than when using a base layer formed only of a plurality of holes without a nozzle.

At this time, the thickness of the micro-nozzle 120 becomes thinner in the direction protruding from the portion in contact with the base layer, and may be in the form of horns such as polygonal horns or cones. As a preferred example, as shown in Figure 2 may be a square horn (miniature pyramid structure). Referring to FIG. 2, the micro nozzle may have a structure inclined in a protruding direction, and may have a through portion connected to a hole in the base layer at the center.

In addition, the outer diameter of the micro-nozzle 120 becomes smaller in a direction protruding from a portion in contact with the base layer 110, and the inner diameter of the micro-nozzle may be the same. As a result, the distance between the outer diameter and the inner diameter of the micro nozzle may be reduced.

Furthermore, as shown in FIG. 2, in the micro-nozzle array 100, a total of 61 nozzles may be regularly arranged in a regular hexagonal arrangement. The distance between the micro nozzles may be 1 mm to 3 mm, may be 1.5 mm to 2.5 mm, and may be 2 mm.

, 내경

을 가지는 원통 구조 노즐의 Cone jet 모드 개시전압을 나타낸 식이다.The structure of the micro-nozzle 120 is designed to minimize the gap between the outer diameter and the inner diameter of the nozzle, and is closely related to the reduction in the diameter of the nozzle. Equation 1 is the outer diameter

, Inner diameter

Cone jet mode starting voltage of a cylindrical structure nozzle having a formula.

[Equation 1]

은 Cone jet 모드 개시전압,

는 표면장력,

는 진공에서의 유전율,

는 노즐과 접지 극과의 거리를 나타낸다.)(In Equation 1 above

Is Cone jet mode start voltage,

Is the surface tension,

Is the dielectric constant in vacuum,

Indicates the distance between the nozzle and the ground pole.)

If the nozzle has the same inner diameter, the smaller the outer diameter, the lower the start voltage of the Cone jet mode can be, but in a typical cylindrical structure, it is difficult to implement because it forms a thin wall. However, the micro-nozzle having a special structure provided by the present invention has an advantage of minimizing the distance between the outer diameter and the inner diameter because it is not restricted to the problem.

In addition, the micro-nozzle array 100 includes a plurality of pillars 130 protruding from the base layer 110 in the same direction in which the micro-nozzles protrude between the one or more micro-nozzles 120. can do.

The plurality of pillars 130 have a shorter protruding length than the plurality of micro nozzles 120, and can prevent droplets discharged through each of the plurality of micro nozzles from sticking to the micro nozzle array 100 during electrostatic spraying. have.

In addition, in another aspect of the present invention

a) performing anisotropic etching on the substrate to form a shape corresponding to the micro nozzle of the micro nozzle array;

b) after depositing the photoresist on the substrate, patterning the photoresist so that a hole in the micro nozzle is formed;

c) preparing a master by filling a metal with the photosensitive agent patterned on the substrate;

d) filling the master with metal to prepare a metal mold;

e) filling the metal mold with a polymer to produce a micro-nozzle array; a method for manufacturing a micro-nozzle array is provided.

At this time, the flow of the manufacturing method of the micro-nozzle array based on the metal mold provided in another aspect of the present invention is shown in FIG.

Hereinafter, a method of manufacturing a micro-nozzle array provided in another aspect of the present invention will be described in detail with each step with reference to FIG. 3.

First, a method of manufacturing a micro nozzle array provided in another aspect of the present invention includes a) performing anisotropic etching on a substrate to form a shape corresponding to the micro nozzle of the micro nozzle array.

Specifically, the step a) is a-1) forming a silicon nitride on the substrate; a-2) patterning a photosensitive agent on the silicon nitride to form a shape corresponding to the micronozzle of the micronozzle array of claim 1; a-3) performing anisotropic etching; And a-4) removing silicon by performing a reactive ion etching (RIE) process using the patterned photoresist as a mask. In more detail, after applying a photosensitive agent on the silicon substrate (silicon wafer) on which silicon nitride is deposited, patterning with UV to form a mask for the RIE process, and then performing the RIE process to remove the photosensitive agent on the surface at the same time By removing a portion of the silicon nitride, holes for anisotropic etching are formed. Thereafter, anisotropic etching of 40 μm to 60 μm may be performed in a depth direction of the silicon substrate. In addition, a-5) removing the silicon nitride; may further include.

Next, a method of manufacturing a micro nozzle array provided in another aspect of the present invention includes b) depositing a photoresist on a substrate, and then patterning the photoresist so that holes in the micro nozzles are formed.

Specifically, the method may further include depositing a metal on the substrate before performing step b), and further comprising depositing the metal on the patterned photoresist after performing step b). The metal may be chromium and copper.

In addition, the step b) may be patterning the photosensitive agent so that a hole having a depth of 50 μm to 200 μm is formed, or patterning the photosensitive agent so that a hole having a depth of 80 μm to 150 μm is formed.

Further, before performing step b), patterning a region in which a plurality of pillars are to be formed is patterned with a photosensitizer; And removing silicon using a patterned photoresist as a mask using an RIE process to further form a plurality of pillar regions.

Specifically, a micronozzle array having a hydrophobic surface can be fabricated later by forming a plurality of circular holes in a region excluding the micronozzle on the silicon substrate through photoresist patterning and RIE process. Subsequently, after chromium and copper are sequentially deposited, THB-based negative photoresist is patterned using UV to form a column having a height of 100 μm. Thereafter, chromium and copper are deposited once more.

Next, a method of manufacturing a micro-nozzle array provided in another aspect of the present invention includes c) preparing a master by filling the patterned substrate with a metal.

The metal may be nickel.

Specifically, the master may be manufactured by performing primary electroforming with nickel.

Next, the manufacturing method of the micro-nozzle array provided in another aspect of the present invention includes a step of preparing a metal mold by filling the master with metal.

The metal may be nickel.

Specifically, it is possible to prepare a metal mold as a stamp by performing secondary electroforming with nickel. It can be used as a metal mold for mass production of micro nozzle arrays.

Next, a method of manufacturing a micro-nozzle array provided in another aspect of the present invention includes the step of e) filling the metal mold with a polymer to produce a micro-nozzle array.

The polymer may be a thermosetting polymer or polydimethylsiloxane (PDMS).

Specifically, casting a thermosetting polymer such as PDMS to the metal mold and separating it from the mold can produce a micro-nozzle array of non-conductive material.

Referring to Figure 4, it can be confirmed the manufacturing result of the micro-nozzle array. The micro-nozzle of the micro-nozzle array is composed of a number of cylinders adjacent to each other at regular intervals from the square-shaped nozzle. A nozzle having a bottom surface of 130 μm in width and 130 μm in length and a hole of 50 μm protrudes to a height of 50 μm, and the inclined surface of the square horn is also inclined 54.74 degrees with respect to the horizontal surface. This represents the inclination angle between the <100> plane and the <111> plane according to the anisotropic etching of the silicon substrate. Cylinders with a diameter of 13 μm and a height of 20 μm adjacent to the nozzle are structures designed for the hydrophobic surface of the micronozzle array. By arranging such cylinders on the surface, droplets can be prevented from forming on the nozzle surface, and finally a stable electrostatic spraying is possible.

In addition, in another aspect of the present invention

A fluid supply 1100; A power supply 1200; Electrostatic spray droplet generation unit 1300; And the electrostatic spraying system 1000 comprising a counter electrode (1400),

The electrostatic spray droplet generating unit 1300 is provided with an electrostatic spray system 1000, characterized in that it comprises the micro-nozzle array 100.

Referring to FIG. 5, the power supply unit 1200 including the fluid supply unit 1100, the positive electrode high voltage power supply unit 1210, and the negative electrode high voltage power supply unit 1220, the electrostatic spray droplet generation unit 1300, and the counter electrode 1400. It shows the electrostatic spray system consisting of. In addition, the relay 1500 may be further included.

The fluid supply unit 1100 may be a syringe pump capable of supplying fluid, for example, water at a uniform flow rate.

Referring to FIG. 6, the electrostatic spray droplet generation unit 1300 includes a fluid storage tank 1310; An upper cover 1320 covering the upper portion of the fluid storage tank; A lower cover 1330 located under the fluid storage tank; And it may include a micro-nozzle array 100 located at the bottom of the lower cover. In addition, the extraction plate 1340 may be further included under the micro nozzle array. The extraction plate can be grounded with a power supply, and by including the extraction plate in the electrostatic spraying system, an electric field crosstalk problem and a space phone problem can be alleviated.

Further, the tank for storing the fluid supplied from the syringe pump, including the micro-nozzle array, may include various covers (upper cover, lower cover), O-rings, and bolts capable of sealing the fluid. The extraction plate is precisely aligned with the microscopic pyramid nozzle array to alleviate the electric field crosstalk problem between nozzles and the formation of space charge caused by charged droplets. In order to prevent the phenomenon that the charged droplets return to the extraction plate again, counter electrodes are installed with the opposite polarity of the droplets under the extraction plate, and the diffusion degree of the droplets can be controlled according to the applied voltage. The counter electrode may be disposed spaced apart from the micro nozzle array of the electrostatic spray droplet generation unit.

Furthermore, in another aspect of the present invention

Fluid supply; Power supply; Electrostatic spray droplet generation unit; And the electrostatic spray system comprising a counter electrode,

The electrostatic spray droplet generating unit is provided with a humidifying sterilizer comprising an electrostatic spray system characterized in that it comprises the micro-nozzle array of claim 1.

Water nano droplets generated through the electrostatic spray system provided in another aspect of the present invention may perform a fine dust collection function and a microbial sterilization function. This is due to the property that the droplet has a charge, and accordingly, the function of charging fine dust in the air and drawing it into the dust collecting plate and sterilizing function through charge transfer or radical can be performed. Through this, it is possible to provide a humidifying sterilizer including the electrostatic spray system of the present invention.

Although the present invention has been described in detail through exemplary embodiments above, those skilled in the art to which the present invention pertains understand that various modifications are possible within the limits of the embodiments described above without departing from the scope of the present invention. will be. Therefore, the scope of rights of the present invention should not be limited to the described embodiments, but should be determined by any modified or modified form derived from the claims and equivalent concepts as well as the claims described below.

100: micro nozzle array
110: base layer
120: micro nozzle
130: pillar
1000: electrostatic spraying system
1100: fluid supply
1200: power supply
1210: anode high voltage power supply
1220: cathode high voltage power supply
1300: electrostatic spray droplet generation unit
1310: fluid storage container
1320: top cover
1330: lower cover
1340: extraction
1400: counter electrode
1500: relay

Claims (13)

A base layer comprising at least one hole; And
At least one micro-nozzle surrounding each of the at least one hole from the base layer and protruding from a region having a predetermined thickness, wherein the thickness becomes thinner in a direction protruding from a portion in contact with the base layer; Micro nozzle array comprising a.
According to claim 1,
The micro-nozzle is a micro-nozzle array, characterized in that the horn shape.
According to claim 1,
The micro-nozzle array is characterized in that the outer diameter of the micro-nozzle becomes smaller in a direction protruding from a portion in contact with the base layer, and the inner diameter of the micro-nozzle is the same.
According to claim 1,
The micro nozzle array,
The micro-nozzle array comprising a plurality of pillars protruding from the base layer in the same direction as the direction in which the micro-nozzles protrude between the one or more micro-nozzles.
a) performing anisotropic etching on the substrate to form a shape corresponding to the micro-nozzle of the micro-nozzle array of claim 1;
b) after depositing the photoresist on the substrate, patterning the photoresist so that a hole in the micro nozzle is formed;
c) preparing a master by filling a metal with the photosensitive agent patterned on the substrate;
d) filling the master with metal to prepare a metal mold;
e) manufacturing a micro-nozzle array by filling the metal mold with a polymer.
The method of claim 5,
Step a) is,
a-1) forming silicon nitride on a substrate;
a-2) patterning a photosensitive agent on the silicon nitride to form a shape corresponding to the micronozzle of the micronozzle array of claim 1;
a-3) performing anisotropic etching; And
a-4) removing silicon by performing a reactive ion etching (RIE) process using the patterned photoresist as a mask.
The method of claim 5,
The method further comprises depositing a metal on the substrate before performing step b), and further comprising depositing the metal on the patterned photoresist after performing step b).
The method of claim 5,
The step b) is a manufacturing method of a micro-nozzle array, characterized in that the photoresist is patterned to form a hole having a depth of 50 μm to 200 μm.
Fluid supply; Power supply; Electrostatic spray droplet generation unit; And the electrostatic spray system comprising a counter electrode,
The electrostatic spray droplet generating unit comprising the micro-nozzle array of claim 1.
The method of claim 9,
The electrostatic spray droplet generation unit,
Fluid storage tanks;
An upper cover covering the upper portion of the fluid storage tank;
A lower cover located under the fluid storage tank; And
Electrostatic spray system comprising a micro-nozzle array located at the bottom of the lower cover.
The method of claim 9,
The counter electrode is an electrostatic spray system that is disposed spaced apart from the micro nozzle array of the electrostatic spray droplet generation unit.
The method of claim 9,
The electrostatic spray droplet generating unit comprises an electrostatic spray system characterized in that it comprises a power supply and a groundable extraction plate.
Fluid supply; Power supply; Electrostatic spray droplet generation unit; And the electrostatic spray system comprising a counter electrode,
The electrostatic spray droplet generation unit humidifying sterilizer comprising an electrostatic spray system, characterized in that it comprises the micro-nozzle array of claim 1.

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