KR100644861B1 - A method of fabricating microchannel using surface tension and the microchannel - Google Patents

Abstract

The present invention relates to a method for producing microtubules using surface tension, and a microtubule thereof, and in particular, microtubules having cross-sections of various areas and shapes can be easily manufactured using liquid polymers and solid polymers without concern of chemical contamination. It is about how it can be.

The present invention provides a method for fabricating microtubules using surface tension between a liquid polymer and a solid polymer, wherein the adhesion between the liquid polymer and the solid polymer is greater than the cohesion force inside the liquid polymer.

According to the method of manufacturing a microtubule using the surface tension according to the present invention, it is possible to manufacture a microtubule having a variety of cross-sections, such as circular, elliptical, the fluid flow is not limited due to the shape of the microtubule cross-section, do not use a chemical solution As a result, chemical contamination in the microtubules can be prevented, and thus it can be widely used in fields such as biotechnology and sensor engineering. In addition, it is possible to produce a microtubule having a desired cross-sectional shape in a short time, the cross-sectional area of the microtubule can also be conveniently adjusted.

Description

Microtubule fabrication method using surface tension and its microtubules {A method of fabricating microchannel using surface tension and the microchannel}

Figure 1a is a conventional microtubule manufacturing process using wet etching,

Figure 1b is a conventional microtubule manufacturing process using dry etching,

Figure 1c is a conventional microtubule manufacturing process using a micro molding technique,

Figure 2a is a graph showing the calculation of the friction loss in the microtubule according to the shape of the microtubule cross section by computer simulation;

Figure 2b is a graph showing the velocity distribution in the microtubules when the cross-sectional shape of the microtubules is a square,

Figure 2c is a graph showing the velocity distribution when the shape of the microtubule cross section is semicircular,

2d is a graph showing the velocity distribution when the cross section of the microtubule is circular;

3 is a conceptual diagram of a method for manufacturing microtubules according to the present invention;

4 is a process chart of the method for manufacturing microtubules according to the present invention;

Figure 5a is an embodiment of a microtubule produced by the microtubule manufacturing method according to the present invention, and

Figure 5b is another embodiment of the microtubules produced by the microtubule manufacturing method according to the present invention.

The present invention relates to a method for producing microtubules using surface tension, and a microtubule thereof, and in particular, microtubules having cross-sections of various areas and shapes can be easily manufactured using liquid polymers and solid polymers without concern of chemical contamination. It is about how it can be.

Recently, due to the development of precision processing technology, micro sized structures have been manufactured and used in various fields. The precision processing technology is widely used in the field of gas sensors and biotechnology, including the production of microtubules for the movement of fluid.

As a method for manufacturing the microtube, a method using a semiconductor process and a precision machining method are used.

Methods for making microtubules using the semiconductor process may be largely classified into a method using wet etching and a method using dry etching.

In the wet etching method, a pattern is formed on a substrate by using photo lithography, and an etchant such as hydrofluoric acid (HF) and potassium hydroxide (KOH) is injected between the formed patterns, and a photoresist ( It is a method of etching by causing a chemical reaction with an uncovered part.

Like the method using wet etching, the method using the dry etching illustrated in FIG. 1B is also a method of physically or chemically etching an inert gas through a pattern formed using a photolithography process.

Substrates formed using the wet etching and the dry etching are manufactured as microtubules through a process of bonding with another substrate.

Meanwhile, in addition to the above two methods, micro-moulding can be made by using micro-molding. This method uses a semiconductor processing technique or a precision processing technique to make a mold, and injects a liquid material into the mold mold and solidifies it. This is how you do it. In FIG. 1C, a method of fabricating microtubules using micro molding is illustrated.

The microtube manufactured by the above method is widely used in the field of lab on a chip (LOC) or microfluidics, and is used for the movement and reaction of various biological materials including fluids. Have The microtubes are mainly manufactured to have a rectangular cross section because it is difficult to make cross sections of other shapes by the conventional method.

The shape of the microtubule cross section affects the flow of the fluid, etc. Hereinafter, the influence of the shape of the cross section on the flow of the fluid will be described.

) 수이며, 유체의 속도(V), 동 점성계수(

), 관의 안지름(d)에 관한 함수이다. y축은 유체가 일정 길이의 수평 채널을 통과할 때의 압력손실(압력강하)을 나타내며, 압력손실은

식으로 주어진다. 여기서 f는 마찰계수, L은 관의 길이, Dh는 수력직경,

는 유체의 밀도를 나타낸다. FIG. 2A shows the pressure loss due to a change in velocity (change of Reynolds number), with all other variables fixed except for the velocity of the fluid. The x-axis is one of the dimensionless numbers that separates laminar and turbulent flows.

), The velocity of the fluid (V), the kinematic viscosity (

), Which is a function of the inner diameter (d) of the pipe. The y-axis represents the pressure loss (pressure drop) as the fluid passes through a horizontal channel of constant length.

Given by Where f is the coefficient of friction, L is the length of the pipe, Dh is the hydraulic diameter,

Represents the density of the fluid.

As shown in FIG. 2A, as the number of Reynolds increases, that is, as the speed increases, the pressure drop increases, and the circular cross-sectional structure has a smaller pressure drop than the rectangular cross-sectional structure. The reason is that friction loss (pressure drop) in laminar horizontal tube flow depends only on the viscous shear force, and the viscous shear force increases closer to the wall surface. In other words, the wall shape in the fluid flow is closely related to the friction loss.

2B, 2C, and 2D illustrate the velocity distribution of the fluid in the microtubules having the circular, semicircular, and quadrangle shapes having the same cross-sectional area, respectively, in order to verify the relationship between the wall shape and the frictional loss.

As shown, there is almost no flow of fluid at the corners of the microtubules with square and semicircular cross-sectional areas, which can result in the flow of fluid at the corners being blocked and laminated, resulting in clogging of the microtubules. May cause.

On the other hand, in a microtubule having a circular cross section, the velocity distribution appears evenly, which is more suitable for a smooth flow of fluid than a microtubule having a different cross section.

Therefore, it is preferable to make a microtubule having a circular cross section, but the conventional wet etching method has a disadvantage in that the selection is limited in the materials (glass type) and the etchant that can be isotropically etched. It has a long disadvantage and is not suitable. For example, when using a hydrofluoric acid (HF) on a glass substrate to make a circular channel of 100 micrometers, it takes more than 90 minutes because the glass substrate is etched at about 1.5 micrometers per minute.

In addition, the method using dry etching is a principle that the gases excited in the plasma state are etched by the chemical reaction generated on the surface or the surface collision with the atoms excited in the plasma state, so it is very difficult to make the desired curved shape. The technique has the disadvantage of uniformly etching depths of several hundred micrometers or more.

In addition, the method using the micro-molding technique has a disadvantage that it is difficult to make a curved surface when manufacturing the mold.

In addition, the conventional methods have the disadvantage of not being able to completely prevent the contamination of the fluid because of the use of chemicals and the disadvantage of having a separate bonding process.

The present invention is to solve the problems of the conventional methods as described above, while producing a microtubule having a curved cross section without chemical contamination, to propose a microtubule manufacturing method that can be produced more easily and quickly.

The present invention provides a method for fabricating microtubules using surface tension between a liquid polymer and a solid polymer, wherein the adhesion between the liquid polymer and the solid polymer is greater than the cohesion force inside the liquid polymer.

Preferably, solidifying the liquid state polymer in a state in which the liquid state polymer is attached to a wall of the solid state polymer.

Preferably, the microtubule can be produced without using a separate bonding agent. That is, only the operation of solidifying the liquid polymer in the state in which the liquid polymer is attached to the wall of the solid polymer, combined with the solid polymer to form an integral structure, the bonding agent throughout the microtube manufacturing process There is no need to use such chemicals, so there is no fear of contamination inside the microtube due to chemicals.

Preferably, after inverting the top and bottom of the structure produced by the solidification, the structure is placed on the same liquid polymer as the liquid polymer, and the liquid polymer is attached to the wall of the solid polymer of the structure. The method may further include solidifying the liquid polymer in a state. By going through the solidification step, microtubules having various cross-sectional areas and shapes allowing various fluids to flow can be formed.

Preferably, the solid-state polymer is disposed so that the walls of the solid-state polymer to which the liquid-state polymer is attached are connected to each other, and a three-dimensional space in which the liquid-state polymer attached to the wall of the solid-state polymer and solidified is a closed curved surface. Can be formed. For example, a cube of solid state polymers having the same volume on the same imaginary plane is arranged such that each corner is in contact with each other, that is, with the same volume of empty space between the solid state polymers. If placed on a liquid polymer, the liquid polymer will adhere to all four walls according to the property of adhesion between the liquid polymer and the solid polymer to be greater than the cohesive force inside the liquid polymer. If solidified in the attached state, the liquid polymer may be formed in the form of hemispheres. Thereafter, the top and bottom of the structure formed by the above process is inverted and placed on the same liquid polymer as the liquid polymer, and the liquid polymer is solidified in a state in which it is attached to the wall of the solid polymer of the structure. It is possible to form a three-dimensional space formed of various shapes of closed curved surfaces. The three-dimensional space formed as a closed curved surface as described above may be configured in various ways by freely selecting the number, size, etc. of the solid-state polymer, the three-dimensional space formed by the above method is a living body including cells, etc. without concern for chemical contamination It may be used to store material.

Preferably, the cross-sectional area and the shape of the cross section of the microtubule may be adjusted.

Preferably, the solid-state polymer is disposed long in the longitudinal direction of the microtubules to be produced, it may be configured to be spaced apart from each other by a predetermined distance. That is, the solid state polymer before the liquid state polymer is solidified may have a shape of a rectangular parallelepiped disposed in the longitudinal direction of the microtube to be produced, and the two solid state polymers may be parallel to each other by a predetermined distance from each other. May be arranged.

Preferably, the solid state polymer is disposed elongated in the longitudinal direction of the microtubule to be produced, but connected by a plane parallel to the plane in which the liquid state polymer is placed so that the solid state polymer is attached to the wall surface of the solid state polymer. The solid state of the liquid polymer can be formed to form microtubules.

Preferably, the cross-sectional area of the microtubule can be controlled by the thickness of the liquid state polymer. For example, if the thickness of the liquid polymer is thickened, the amount of liquid polymer attached to the solid polymer will be increased, thereby reducing the cross-sectional area of the microtubule to be produced. Conversely, when the thickness of the liquid polymer is thinned, the amount of liquid polymer attached to the solid polymer decreases, and in this case, the cross-sectional area of the microtubule to be produced is increased.

Preferably, the shape of the cross section of the microtubule may be controlled by the thickness of the liquid state polymer. For example, when the thickness of the liquid polymer is thickened, the liquid polymer has a circular or semicircular cross section because the cross section to be formed is close to a circle. In contrast, when the thickness of the liquid polymer is made thinner, the cross section of the liquid polymer is less likely to be circular, and the amount of the liquid polymer attached to the solid polymer is reduced, thereby reducing the elliptical or semi-elliptic cross section. Have

Preferably, the shape of the cross section of the microtubule may be varied by the arrangement shape of the solid state polymer. For example, when the array shape of the solid state polymer is a shape of a rectangular parallelepiped arranged at a predetermined distance in parallel to each other, the cross section of the microtubule may have an elliptical or circular shape. On the contrary, if the shape of the solid state polymer maintains the shape of the rectangular parallelepiped and is connected in a plane parallel to the plane in which the liquid state polymer exists, the cross section of the microtubule may have a semi-elliptic or semi-circular shape.

Preferably, the shape of the cross section of the microtubule includes a shape such as a circle, an ellipse, a semicircle and a semi-ellipse.

Preferably, the liquid state polymer may be disposed by spin coating on a substrate composed of the same material as the solid state polymer.

Preferably, the liquid state polymer and the solid state polymer may be a PolyDiMethylsiloxane Stamp (PDMS). Since the PDMS is a polymer that is harmless to many living bodies including the human body, the microtubules manufactured using the PDMS can be used for the movement of various fluids including cells and the like.

The present invention relates to a microtubule produced by the above method.

Hereinafter, the principles and embodiments of the present invention will be described with reference to the accompanying drawings.

)이 90도 미만이 되기 때문에, 상기 고체 상태 폴리머 벽면과 인접한 액체 상태 폴리머가 상기 고체 상태 폴리머 벽면을 따라 상승하게 되고, 곡면을 형성하여 반원형 단면의 채널이 구현된다.Figure 3 shows the concept of a microtubule manufacturing method according to the present invention, by making a temporary channel (solid polymer) of the rectangular cross section through the injection molding or drilling process, a thin fluid on the substrate through a spin coating process After forming a film (liquid polymer), the solid polymer is placed on a substrate on which the liquid polymer is formed, and the adhesion of the liquid polymer to the polymer wall of the solid polymer is increased. Because of greater than the intermolecular cohesion, that is, the angle between the polymer wall in the solid state and the polymer in the liquid state (

) Is less than 90 degrees, the liquid polymer adjacent to the solid state polymer wall rises along the solid state polymer wall, and forms a curved surface to realize a channel of semicircular cross section.

In this case, the width (w) of the channel, the thickness of the liquid polymer and the height at which the liquid polymer rises along the solid polymer wall may be adjusted, and thus, microtubules of various cross sections may be manufactured.

For example, the length b of the transverse axis of the ellipse is determined by the distance w between the solid state polymers, and the length a of the longitudinal axis of the ellipse is the thickness of the liquid state polymer and the liquid state polymer wall of the solid state polymer. Since it is determined by the height which rises accordingly, the cross section of the produced microtubule can be adjusted by making the distance between the said solid state polymers close, or making the thickness of the said liquid state polymer thick.

3, 4, 5a and 5b by way of example to illustrate the PDMS (poly-dimethylsiloxane) is relatively easy to process and suitable for bio-applications for the production of the microtubules, the polymer used in the present invention is shown in the PDMS The limitation is obvious to one of ordinary skill in the art.

4 shows a process sequence of a method for manufacturing microtubules according to the present invention.

A PDMS substrate S2 is formed on the silicon substrate, and a liquid PDMS film is spin coated on the PDMS substrate S2. Separately, the PDMS channel S1 is made through an injection molding or a punching process.

Subsequently, when the PDMS channel S1 is lowered onto the liquid PDMS layer, the liquid PDMS rises along the wall surface of the PDMS channel S1 to have a curved surface curved in the direction of gravity. At this time, the rise of the liquid PDMS along the wall surface of the PDMS channel (S1) is due to the property that the adhesion force with the PDMS channel (S1) is greater than the cohesion between the liquid PDMS, that is, the surface tension. The liquid phase PDMS solidifies the liquid phase PDMS while the liquid phase PDMS rises along the wall surface of the PDMS channel S1 by the surface tension.

When the liquid PDMS solidifies, the PDMS channel S1, the liquid PDMS, and the PDMS substrate S2 are integrated, and the integrated PDMS structure (hereinafter, referred to as a 'top layer' of a microtube) is silicon. Separate on the substrate.

Thereafter, the same process is repeated. After the PDMS substrate S3 is formed on the silicon substrate, the liquid PDMS is spin-coated to form a thin film thereon. Then, the top and bottom portions of the upper layer of the microtube are inverted and placed on the liquid PDMS coated on the PDMS substrate S3.

At this time, the liquid PDMS is raised along the wall surface of the PDMS channel portion of the upper layer, as in the manufacturing process of the upper layer, and solidified the liquid PDMS in the state raised along the wall coupled with the existing upper layer of the fluid An integral structure is formed to support the flow.

In this case, the cross section of the microtubule may be implemented in various shapes, and may be implemented in various areas by the thickness of the liquid PDMS, the distance between the PDMS channels (S1), and the like.

Figure 5a is an embodiment of the microtubules produced by the microtubule manufacturing method according to the present invention, Figure 5b shows another embodiment of the microtubules produced by the microtubule manufacturing method according to the present invention.

Figure 5a shows the shape of the cross-section of the microtube formed by using a liquid PDMS after fixing the PDMS channel (S1) in Figure 4 by the mold and fixed to a thickness of 1000 micrometers. Each increases the height of adhesion to the PDMS channel wall by increasing the thickness of the deposited liquid PDMS, indicating that the longitudinal axis can be adjusted to 1000 micrometers, 650 micrometers, and 500 micrometers, respectively, to create circular and elliptical cross sections. .

5B shows a microtubule having a semi-elliptical cross section and a semi-circular cross section. Unlike the manufacturing method of FIG. 5A, in a state in which the PDMS channel S1 is connected in a plane parallel to the liquid PDMS-coated PDMS substrate, The cross section of the produced microtubule is shown.

That is, unlike the PDMS channel S1 in FIG. 5A, which is spaced apart from each other, the wall surface of the PDMS channel S1 is used by using the PDMS channel S1 connected by a plane parallel to the surface on which the liquid PDMS is placed. The microtube is manufactured by performing the process of solidifying only once with the liquid PDMS attached thereto. At this time, the cross section of the resulting microtubules is determined to be semi-elliptical and elliptical according to the thickness of the liquid PDMS.

Each of the microtubules shown in FIG. 5B increases the height of the liquid PDMS attached to the channel wall by increasing the thickness of the deposited liquid PDMS, thereby adjusting the longitudinal axis to 1000 micrometers, 500 micrometers, and 300 micrometers, respectively. to be.

According to the method of manufacturing a microtubule using the surface tension according to the present invention, it is possible to manufacture a microtubule having a variety of cross-sections, such as circular, elliptical, the fluid flow is not limited due to the shape of the microtubule cross-section, do not use a chemical solution As a result, chemical contamination in the microtubules can be prevented, and thus it can be widely used in fields such as biotechnology and sensor engineering. In addition, it is possible to produce a microtubule having a desired cross-sectional shape in a short time, the cross-sectional area of the microtubule can also be conveniently adjusted.

Claims (21)

A method for producing microtubules using surface tension between a liquid polymer and a solid polymer, Solidifying the liquid polymer in a state in which the liquid polymer is attached to a wall of the solid polymer; And After inverting the top and bottom of the structure formed by solidifying in the step, the structure is placed on the same liquid polymer as the liquid polymer, and the liquid polymer is attached to the wall of the solid polymer of the structure. And a second step of solidifying the liquid-state polymer. delete delete delete delete delete The method of claim 1, In the first step, the solid-state polymer is disposed long in the longitudinal direction of the microtubules to be produced, characterized in that two solid-state polymers are present and separated from each other by a predetermined distance, a method for producing a microtubule using surface tension . The method of claim 1, In the first step, the solid state polymer is disposed elongated in the longitudinal direction of the microtubule to be produced, but is connected by a plane parallel to the plane in which the liquid state polymer is placed so as to be attached to the wall of the solid state polymer. And forming a microtubule by solidifying the liquid-state polymer. delete delete delete delete The method of claim 1, The method of claim 1, wherein the liquid state polymer is disposed on the substrate made of the same material as the solid state polymer by spin coating. The method of claim 1, In the first step, the solid state polymer is disposed such that all of the wall surfaces of the solid state polymer to which the liquid state polymer is attached are connected, and the liquid state polymer attached to the wall surface of the solid state polymer and solidified consists of a closed curved surface. Microtubule manufacturing method using surface tension, characterized in that to form a three-dimensional space. delete A microtubule made by the method of claim 1, 7, 8, 13 or 14. The method of claim 16, And the cross-sectional area of the microtubule is controlled by the thickness of the liquid polymer. The method of claim 16, The shape of the cross section of the microtubules is controlled by the thickness of the liquid polymer, the microtubules using surface tension. The method of claim 16, The shape of the cross section of the microtubule is characterized in that it depends on the array shape of the solid state polymer, microtubules using surface tension. The method of claim 16, The shape of the cross section of the microtubules is characterized in that it comprises a shape selected from the group consisting of circular, elliptical, semi-circular and semi-elliptic, microtubules using surface tension. The method of claim 16, The liquid state polymer and the solid state polymer is characterized in that the PDMS (PolyDiMethylsiloxane Stamp), the microtubes using surface tension.

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