CN112517309B - Mesh microstructure for high-viscosity liquid atomization and manufacturing method thereof - Google Patents

Abstract

The invention discloses a mesh microstructure for high-viscosity liquid atomization and a preparation method thereof. The manufacturing method includes: making a mesh template, wherein the mesh template has an array of convex pillars; forming a mesh material layer on a substrate; imprinting the mesh template on the mesh material layer, wherein the mesh material layer is printed on the mesh template. The convex column array is completely immersed in the mesh material layer, and the mesh material layer is cured; the mesh template and the substrate are removed to obtain a vibrating diaphragm, wherein the vibrating diaphragm and the A mesh hole is formed at the position facing the convex column array. The mesh microstructure can realize the normal temperature atomization of liquid from low viscosity to high viscosity, and the atomization is sufficient, the atomized droplet volume is small, the flow rate is large, the mesh surface is flat, firm and easy to clean, and the production method is stable and easy to clean. Easy to repeat.

Description

Mesh microstructure for high-viscosity liquid atomization and method for making the same

technical field

The invention belongs to the technical field of liquid atomization, and in particular relates to a mesh microstructure used for high-viscosity liquid atomization and a manufacturing method thereof.

Background technique

The mesh microstructure for high-viscosity liquid atomization is a spray device that drives the mesh sheet to vibrate through the vibration of the piezoelectric sheet, contacts the liquid, and drives the liquid to spray. Among them, the mesh diameter of the liquid outlet surface on the vibrating mesh sheet is a key factor in determining the diameter of the atomized droplets, and the microstructure of the mesh is one of the factors determining the viscosity of the atomized liquid. At present, the main methods of realizing the vibrating mesh microstructure in the industry are laser ablation, chemical etching or electroforming technology. The aperture and morphology requirements of the atomized mesh, and the selection of materials are greatly limited by the manufacturing technology, which is difficult to meet. Small pore size, especially the pore size of 1-2 μm in diameter or the atomization requirements of high viscosity liquids at room temperature.

SUMMARY OF THE INVENTION

(1) Technical problem to be solved by the present invention

The technical problem solved by the present invention is: how to make a mesh microstructure for high-viscosity liquid atomization capable of spraying high-viscosity liquid.

(2) Technical scheme adopted in the present invention

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

A method for making a mesh microstructure for high-viscosity liquid atomization, the making method comprising:

making a mesh template, wherein the mesh template has an array of convex pillars;

Fabricating and forming a mesh material layer on the substrate;

stamping the mesh material layer on the mesh template, wherein the convex pillar array is completely immersed in the mesh material layer, and curing the mesh material layer;

The mesh template and the substrate are removed to obtain a vibrating diaphragm, wherein a mesh hole is formed at the position of the vibrating diaphragm which is opposite to the array of convex pillars.

Preferably, the making method of described mesh template is as follows:

making a silicon stamp, wherein the silicon stamp has an array of silicon cylinders thereon;

forming an imprint layer on a substrate, and imprinting the imprint layer with the fabricated silicon stamp, wherein the silicon cylinder array is completely embedded in the imprint layer;

curing the imprint layer and performing demolding, wherein a groove array is formed on the imprint layer at a position facing the silicon cylinder array;

forming a metal layer on the imprint layer, the metal layer covering the groove array;

The embossing layer and the substrate are removed to obtain a mesh template, wherein a convex column array is formed on a position of the mesh template opposite to the groove array.

Preferably, the radius of the convex columns of the convex column array increases from one end away from the mesh template body to the end close to the mesh template body, and the sides of the convex columns are concave arc surfaces.

Preferably, the manufacturing method further includes removing the residual film of the embossing glue in the mesh.

Preferably, the material of the mesh material layer is polyimide or epoxy resin.

Preferably, the method of making a silicon stamp comprises:

forming a mask pattern layer on the silicon substrate;

etching the silicon substrate to form an array of silicon cylinders;

The mask pattern layer is removed to obtain a silicon stamp.

Preferably, the radius of the mesh hole decreases along the direction from the first surface to the second surface of the vibrating membrane, and the inner wall surface of the mesh hole is an arc surface, wherein the first surface and the second surface are opposite to each other set up.

Preferably, the radius R of the mesh hole and the height H of the mesh hole satisfy the following relationship:

R=a ^-H , wherein H represents the distance between the inner wall surface of the mesh and the first surface, a represents a design constant and a>1.

Or, the radius R of the mesh hole and the height H of the mesh hole satisfy the following relationship:

R=H ^−b , where H represents the distance between the inner wall surface of the mesh and the first surface, b represents a design constant and b>1.

The invention also discloses a mesh microstructure for high-viscosity liquid atomization, which is made by any one of the above-mentioned manufacturing methods.

(3) Beneficial effects

The invention discloses a mesh microstructure for high-viscosity liquid atomization and a preparation method thereof. Compared with the prior art, the invention has the following advantages and beneficial effects: The microstructure of the mesh hole can realize the normal temperature atomization of liquid from low viscosity to high viscosity, and the atomization is sufficient, the atomized droplet volume is small, the flow rate is large, the mesh surface is flat, strong and easy to clean. Stable and easy to repeat.

Description of drawings

Fig. 1 is the flow chart of the manufacture method of the mesh microstructure for high-viscosity liquid atomization of the embodiment of the present invention;

2 is a schematic cross-sectional view of a silicon stamp according to an embodiment of the present invention;

3 is a schematic cross-sectional view of a mesh template of an embodiment of the present invention;

4 is a schematic cross-sectional view of a mesh material layer and a substrate according to an embodiment of the present invention;

5 is a schematic diagram of a mesh template imprinting a mesh material layer according to an embodiment of the present invention;

6 is a schematic cross-sectional view of a mesh microstructure for high-viscosity liquid atomization according to an embodiment of the present invention;

7 is a top view of a mesh microstructure for high viscosity liquid atomization according to an embodiment of the present invention;

Fig. 8 is the variation curve of the exponential function a ^H of the function A containing acceleration with the height H according to the embodiment of the present invention;

FIG. 9 is a curve of the H ^b power function change curve of the function A including the acceleration with the height H according to the embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

In order to solve the situation that the existing vibrating mesh sheet cannot effectively atomize the high-viscosity liquid, the present application proposes a method for making a mesh microstructure for atomizing the high-viscosity liquid. As shown in the flow chart shown in Figure 1, the method for making a mesh microstructure for high-viscosity liquid atomization in this embodiment includes the following steps:

Step S10 : making a mesh template 30 , wherein the mesh template 30 has a convex column array 31 .

Specifically, the mesh template 30 preferably adopts a metal template, and the specific manufacturing method of the mesh template 30 is as follows:

Step S11 : fabricating a silicon stamp 100 , wherein the silicon stamp 100 has a silicon cylinder array 101 thereon.

As shown in Figure 2, specifically, step S11 includes the following steps:

Step S111 : forming a mask pattern layer on the silicon substrate. Specifically, the silicon substrate is first cleaned, and then a dielectric film is deposited on the silicon substrate by plasma enhanced chemical vapor deposition (PECVD). The material of the dielectric film can be silicon oxide or silicon nitride, and finally the dielectric film is subjected to Photolithography and dry etching to form a mask pattern layer.

Step S112 : etching the silicon substrate to form an array of silicon cylinders. Specifically, using the mask pattern layer as a hard mask, the silicon substrate is etched by reactive ion etching (RIE) to form a silicon cylinder array, and the heights of the cylinders 101 on different silicon substrates range from 10 μm to 50 μm.

Step S113 : removing the mask pattern layer to obtain the silicon stamp 100 . Specifically, after the silicon cylinder array 101 is formed, a wet process is used to remove all the dielectric films covering the silicon cylinder array 101 to obtain silicon stamps 100 with different cylinder arrays, wherein the diameters of the cylinders of the silicon cylinder array 101 are The order from one end of the base body to the end close to the silicon base body is sequentially increased. As a preferred embodiment, the diameter of the cylinder ranges from an end away from the silicon substrate body to an end close to the silicon substrate body from 0.5 μm to 5 μm, and the outer surface of the cylinder is a concave arc surface.

Step S12 : forming an imprint layer on the substrate, and imprinting the imprint layer with the silicon stamp 100 , wherein the silicon cylinder array 101 is completely embedded in the imprint layer. Among them, the material of the embossing layer can be selected from PMMA.

Step S13 : curing the imprint layer and performing demolding, wherein a groove array is formed on the imprint layer facing the silicon cylinder array 101 .

Step S14 : forming a metal layer on the imprint layer, the metal layer covering the groove array.

Specifically, the material of the metal layer is preferably nickel. First, a nickel film is deposited on the surface of the embossed layer after demolding, and the nickel film covers the groove array, and then the nickel film is used as the seed layer to form a nickel metal layer on the surface of the embossed layer by electroplating process, and the nickel metal layer Fill the groove pattern.

Step S15 : removing the embossing layer and the substrate to obtain a mesh template 30 , wherein a convex column array 31 is formed on the mesh template 30 at a position facing the groove array.

Specifically, as shown in FIG. 3 , the radius of the convex columns of the convex column array 31 increases from one end away from the mesh template body to the end close to the mesh template body, and the sides of the convex columns are concave arc surfaces.

Step S20 : fabricating and forming a mesh material layer 50 on the substrate 40 .

Specifically, as shown in FIG. 4 , the substrate 40 is a transparent substrate, such as quartz glass, and a mesh material is coated on the substrate 40 to form a mesh material layer, wherein the mesh material can be polyimide or epoxy resin.

Step S30 : embossing the mesh material layer 50 on the mesh template 30 , wherein the convex column array 31 is completely immersed in the mesh material layer 50 , and the mesh material layer 50 is cured, as shown in FIG. 5 shown.

Step S40 : removing the mesh template 30 and the substrate 40 to obtain a vibrating diaphragm 10 , wherein a mesh hole 20 is formed at the position of the vibrating diaphragm 10 facing the convex column array 31 , as shown in FIG. 6 shown.

Further, the manufacturing method further includes: removing the residual film of the embossing glue in the mesh hole 20 .

Specifically, as shown in FIG. 6 and FIG. 7 , the vibrating diaphragm 10 has a first surface 11 and a second surface 12 arranged opposite to each other, and a plurality of mesh holes 20 are arranged in an array and pass through the first surface 11 and the second surface 12 , the radius of the mesh hole 20 decreases along the direction from the first surface 11 to the second surface 12 , and the inner wall surface of the mesh hole 20 is an arc surface. As a preferred embodiment, the inner wall surface of the mesh hole 20 is a convex arc surface facing the first surface 11 .

Further, as a preferred embodiment, the radius R of the mesh hole 20 and the height H of the mesh hole 20 satisfy the following relationship:

(1) R=a ^−H , where H represents the distance between the inner wall surface of the mesh hole 20 and the first surface 11 , a represents a design constant and a>1.

Of course, in other embodiments, the radius R of the mesh hole 20 and the height H of the mesh hole 20 satisfy the following relationship:

(2) R=H ^−b , where H represents the distance between the inner wall surface of the mesh hole 20 and the first surface 11 , b represents a design constant and b>1.

When the radius R of the mesh hole 20 and the height H of the radius satisfy the above relationship (1) or (2), the mesh hole 20 can effectively atomize the high-viscosity liquid. The specific proof process is as follows:

Capillary pressure formula (1):

The surface tension σ and the contact angle θ are determined by the type of liquid and the hydrophilic and hydrophobic properties of the material surface of the vibrating piece, that is, the greater the surface tension, the greater the capillary force. When the contact angle is less than 90 degrees, the greater the contact angle , the smaller the capillary force; when the contact angle is greater than 90 degrees, the direction of the capillary force is reversed. where the surface tension σ and the contact angle θ are quantities related to the liquid and the mesh material. The radius R is a quantity related to the design of the mesh structure. The smaller R is, the greater the capillary force P _cap is; and the greater the variation of R, the greater the gradient of the capillary force pressure P _cap , and the faster the liquid replenishment through the capillary force. sooner.

Further, it is assumed that the radius R of the mesh hole 20 and the height H of the mesh hole 20 satisfy the following exponential function relationship:

R=a ^-H (2)

In order to ensure that the exponential function is monotonically decreasing, a>1 needs to be satisfied, and a is a design constant.

Substituting Equation (2) into Equation (1), the capillary pressure function can be obtained as:

According to Newton's second law, the mesh is subdivided into small segments of ΔH in the height direction, we can get

F=ma ₁ , (4)

Among them, a ₁ is the acceleration, Δm is the liquid mass within the ΔH height, ρ is the density, v is the velocity, and t is the time. It can be seen that the acceleration a ₁ of the microfluid in the mesh is proportional to the capillary pressure P _cap . Further, the acceleration a ₁ of the microfluid in the mesh can be expressed as:

A为含有加速度的函数，并假设设计常数a＝2，利用计算机模拟可得出加速度函数A与网孔高度H的变化关系曲线，如图8所示。According to formula (7), it can be known that the microfluidic acceleration a ₁ in the mesh also increases with the increase of the mesh height H in the form of an exponential function. In order to see the relationship between microfluidic acceleration and mesh height more intuitively, suppose

A is a function containing acceleration, and assuming that the design constant a = 2, the curve of the change between the acceleration function A and the mesh height H can be obtained by computer simulation, as shown in Figure 8.

Since the acceleration driven by capillary force in the mesh hole continuously increases with the height under the above conditions, it will help to overcome the flow resistance which increases with the decrease of the hole diameter; the larger the incremental change of the acceleration driven by the capillary force, the more beneficial Overcome the flow resistance and realize the timely replenishment of the liquid in the mesh to increase the viscosity of the sprayable liquid. So as to meet the needs of a large number of small droplets sprayed by the high-frequency vibrating mesh sheet.

Further, it is assumed that the radius R of the mesh hole 20 and the height H of the mesh hole 20 satisfy the following power function relationship:

R=H ^-b (8)

In order to ensure that the exponential function is monotonically decreasing, it needs to satisfy b>1, where b is a design constant.

Similarly, according to the calculation of equations (3), (4), (5), (6) and (8), we can get,

b＝2，利用计算机模拟可得出加速度函数A与网孔高度H的变化关系曲线，如图9所示。According to formula (9), it can be known that the microfluidic acceleration a ₁ in the mesh also increases with the increase of the mesh height H in the form of an exponential function. Assumption

b=2, the curve of the change relationship between the acceleration function A and the mesh height H can be obtained by computer simulation, as shown in FIG. 9 .

To sum up, when the radius R of the mesh hole 20 and the height H of the mesh hole 20 satisfy the relationship (1) and the relationship (2), the corresponding mesh microstructures used for high-viscosity liquid atomization are sprayed high viscosity liquid.

The mesh microstructure for high-viscosity liquid atomization manufactured by the above preparation method can realize normal temperature atomization from low-viscosity to high-viscosity liquids, and the atomization is sufficient, the volume of atomized droplets is small, the flow rate is large, and the mesh The surface is flat, strong and easy to clean, while the manufacturing method is stable and easy to repeat.

The specific embodiments of the present invention have been described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that the principles and spirit of the present invention, which are defined in the scope of the claims and their equivalents, are not departed from. Under the circumstances, these embodiments can be modified and perfected, and these modifications and improvements should also fall within the protection scope of the present invention.

Claims (7)

1. A method for making a mesh microstructure for atomization of a high viscosity liquid, the method comprising:

making a mesh template (30), wherein the mesh template (30) has an array of posts (31);

forming a mesh material layer (50) on a substrate (40);

imprinting the mesh template (30) into the layer of mesh material (50), wherein the array of posts (31) are fully embedded within the layer of mesh material (50), and solidifying the layer of mesh material (50);

removing the mesh template (30) and the substrate (40) to obtain a vibrating membrane (10), wherein a mesh (20) is formed at a position of the vibrating membrane (10) opposite to the convex column array (31);

the vibrating diaphragm (10) is provided with a first surface (11) and a second surface (12) which are oppositely arranged, a plurality of meshes (20) are arrayed and penetrate through the first surface (11) and the second surface (12), the radius of each mesh (20) is gradually reduced along the direction from the first surface (11) to the second surface (12), the inner wall surfaces of the meshes (20) are cambered surfaces, and the first surface (11) and the second surface (12) are oppositely arranged;

the radius R of the mesh (20) and the height H of the mesh (20) satisfy the following relationship:

R＝a^-Hwherein H represents a distance between an inner wall surface of the mesh (20) and the first surface (11), a represents a design constant and a>1；

Or, the radius R of the mesh (20) and the height H of the mesh (20) satisfy the following relation:

R＝H^-bwherein H represents a distance between an inner wall surface of the mesh (20) and the first surface (11), b represents a design constant and b>1。

2. The method of manufacturing according to claim 1, wherein the mesh template (30) is manufactured as follows:

making a silicon stamp (100), wherein the silicon stamp (100) has an array of silicon cylinders (101) thereon;

forming an imprint layer on a substrate and imprinting said fabricated silicon stamp (100) into said imprint layer, wherein an array of silicon cylinders (101) is completely recessed within said imprint layer;

solidifying the imprinting layer and demolding, wherein a groove array is formed on the position, opposite to the silicon cylinder array (101), of the imprinting layer;

manufacturing and forming a metal layer on the imprinting layer, wherein the metal layer covers the groove array;

removing the imprinting layer and the substrate to obtain a mesh template (30), wherein an array of pillars (31) is formed on the mesh template (30) at positions directly opposite to the array of grooves.

3. The manufacturing method according to claim 1, wherein the radius of the convex columns of the convex column array (31) increases from one end far away from the mesh template body to one end close to the mesh template body, and the side surfaces of the convex columns are concave arc surfaces.

4. The method of claim 1, further comprising removing residual imprint resist within the mesh (20).

5. Method of manufacturing according to claim 1, characterized in that the material of the mesh material layer (50) is polyimide or epoxy.

6. A method of fabricating a silicon stamp (100) as claimed in claim 2, characterized in that the method of fabricating a silicon stamp (100) comprises:

forming a mask pattern layer on the silicon substrate;

etching the silicon substrate to form a silicon cylinder array (101);

the mask pattern layer is removed to obtain a fabricated silicon stamp (100).

7. A mesh microstructure for atomization of high viscosity liquids made by the method of any one of claims 1 to 6.

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