KR101300485B1 - Passive Micromixer - Google Patents

Abstract

The present invention relates to a passive type micromixer, and more particularly, the type of the micromixer used for mixing two different fluids to form a sinusoidal shape, so that a simple configuration can achieve a significantly improved mixing performance compared to the conventional To a fine mixer.
The present invention is characterized in that the passive micromixer comprises two inlets for introducing different fluids, a sinusoidal mixing channel connected to the inlet, and an outlet connected to the mixing channel.

Description

Passive Micromixer {Passive Micromixer}

The present invention relates to a passive type micromixer, and more particularly, the type of the micromixer used for mixing two different fluids to form a sinusoidal shape, so that a simple configuration can achieve a significantly improved mixing performance compared to the conventional To a fine mixer.

In general, a lab-on-chip refers to a device that performs separation, mixing, reaction, and analysis on one chip.

Controlling the mixing of fluids in microdevices such as lab-on-chips, as well as the homogenization of solutions of chemicals in chemical reactions, is a critical challenge in many applications.

The micromixers are small in size, so that most of the flow is laminar, which is a factor that significantly reduces the efficiency of fluid mixing. That is, because the mixing of the fluid depends on molecular diffusion, the mixing proceeds very slowly in the case of laminar flow in which the fluid moves in a regular path.

Therefore, it is very important to study ways to promote the mixing process, and various kinds of fine mixers have been developed in the past decades to facilitate the mixing process, and these are largely active micromixers. And passive micromixers.

Among them, an active micromixer is characterized by being driven by using an external energy source, and has a disadvantage in that it is difficult to manufacture.

In addition, the passive micromixer is characterized by being able to be driven without an external energy source, and is mainly used because of its easy manufacturing, and its channel shape is zig-zag and serpentine. Alternatively, various types of passive micromixers having a circular shape have been developed.

Among them, Korean Patent Publication No. 10-1005676 discloses a passive micromixer, the main technical configuration of which is at least one disposed between the inlet 11 and the outlet 12, as shown in FIG. The first channels 21, 31, 41, 51 and the second channels 22, 32, 42, 52 having different widths have the inlet 23 and the outlet 24 symmetrical with respect to the X axis. The first channel 21, 31, 41, 51 having different widths of different fluids flowing through the inlet 11, including ring-shaped subchannels 20, 30, 40, and 50 connected thereto; Due to the difference in inertia at the point of the outlet 24 intersecting each other through the second channel (22, 32, 42, 52), an unbalanced collision is characterized in that the fluid is mixed.

Such a configuration has an effect of improving the mixing performance of the fluid by causing an unbalanced collision between the fluids to be mixed, but it is difficult to manufacture because two channels having different widths must be used, and the outlet portion 24 Due to the impact of the fluid generated at the) point has a disadvantage in that the speed of the fluid is reduced to slow the mixing of the fluid.

The present invention has been made to solve the above problems, an object of the present invention is to mix the fluid in the microfluidic channel with a simple configuration by making the channel of the micromixer used for mixing the two different fluids to form a sine wave shape It is to provide a passive fine mixer to improve the performance.

According to an aspect of the present invention,

In the passive type fine mixer, it characterized in that it comprises two inlets for different fluids, a sinusoidal mixing channel is connected to the inlet and the outlet is connected to the mixing channel.

In this case, the mixing channel is characterized in that consisting of a connecting portion is formed between the connection portion and the two inlets and the connection portion formed between the connecting portion and the outlet.

In addition, the shape of the mixed channel is characterized in that it is defined by a sine function of the form y = asin (2πx / λ).

The mixed channel may be configured to include five or more peak points.

According to the present invention, by allowing the channels of the micromixers used to mix two different fluids to form a sine wave shape, the mixing performance of the fluids can be improved without reducing the mixing speed of the fluids in the microchannel with a simple configuration. Has an excellent effect.

In addition, according to the present invention, it is possible to improve the mixing performance while simplifying the structure of the microfluidic system, especially the passive micromixer, which is rapidly increasing in demand in the biomedical field. It has an additional effect that can greatly contribute to.

1 is a cross-sectional view showing a conventional passive micromixer.
Figure 2 (a), (b) is a cross-sectional view schematically showing a passive micromixer according to the present invention.
3 (a), (b) and (c) are cross-sectional views showing various embodiments of the mixing channel of the present invention shown in FIG.
4 (a), 4 (b) and 4 (c) show the secondary flow of fluid in the cross section located at the peak point of the mixing channel shown in FIG.
FIG. 5 is a graph showing mixing performance according to the Reynolds number of the mixing channel shown in FIG. 3. FIG.
Figure 6 (a), (b) is a view showing the mixing performance comparison results of the passive micromixer according to the present invention and the conventional passive micromixer.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the passive micromixer according to the present invention.

(A), (b) is a cross-sectional view schematically showing a passive micromixer according to the present invention, Figure 3 (a), (b), (c) is a mixing channel of the present invention shown in FIG. 4 is a cross-sectional view illustrating various embodiments, and FIGS. 4A, 4B, and 4C are diagrams illustrating a secondary flow of a fluid at a cross section located at a peak point of the mixing channel shown in FIG. 3 is a graph showing the mixing performance according to the Reynolds number of the mixing channel shown in Figure 3, Figure 6 (a), (b) is a view showing a comparison of the mixing performance of the passive micromixer according to the present invention and the conventional passive micromixer to be.

The present invention relates to a passive micromixer (100) that allows the channel of the micromixer (100) used to mix two different fluids to form a sinusoidal shape to obtain a much improved mixing performance with a simple configuration. As shown in FIG. 2A, the configuration includes an inlet 110, a mixing channel 120, and an outlet 130 formed of a fine flow path.

In more detail, the inlet 110 serves as a passage for injecting fluid for mixing, and is configured to be separated into first and second inlets 112 and 114 so as to introduce different fluids, respectively. It is.

Next, the mixing channel 120 is one end connected to the inlet 110 to serve as a passage to move while mixing the fluid introduced through the inlet 110, it is configured to form a sine wave as a whole It is.

In more detail, the mixing channel 120 is composed of a connecting portion 122 and the mixing portion 124, the connecting portion 122, as shown in Figure 2 (a), the first and second inlet ( 112 and 114 are connected to form a T-shape at the point where they meet each other so that different fluids introduced through the first and second inlets 112 and 114 can be combined to be introduced into the mixing unit 124. The mixing unit 124 serves to mix different fluids introduced through the connection unit 122 and is configured to form a sinusoidal shape as a whole, so that a peak portion and a trough portion are formed. It is configured to improve the mixing performance by generating a turbulent flow in the.

That is, the shape of the mixing portion 124 of the mixing channel 120 may be defined as y = asin (2πx / λ), where a means amplitude and λ means pitch or wavelength, x and y represent coordinate values along the width and length, respectively.

Here, amplitude refers to the maximum displacement in the y direction from the center point, ie the neutral position, and the pitch or wavelength is defined as the distance between two consecutive peaks or valleys, which is the same as the conventional notation of sinusoidal function. Therefore, detailed description will be omitted.

Since the sinusoidal mixing channel 120 has a curved portion formed at a peak portion and a valley portion, the mixed fluid is called Dean vortices due to the interaction of inertial force, centrifugal force, and viscous force as the mixed fluid passes through the curved portion. The secondary flows (secondary flows) are generated, and the secondary flows (diffusion) is generated, thereby turbulent flow, thereby improving the mixing performance of the fluid.

In addition, due to the inherent characteristic of the sine function, a passage that forms a substantially straight line is formed at a portion that is not a curved portion, so that a portion in which diffusion occurs in the mixing channel 120 is minimized, thereby further improving the mixing performance of the fluid. This will be described later in more detail together with the experimental results.

Next, the outlet 130 is connected to the other end of the mixing channel 120 to discharge the mixed fluid from the mixing unit 124 to form a sinusoidal shape to the outside.

Hereinafter, with reference to the accompanying drawings will be described in detail the process and the experimental results of mixing the two fluids using the passive micro mixer 100 according to the present invention.

First, the two sine curves forming the cross section of the mixing channel 120 are configured to have an interval of 0.1 mm in the -y direction, and the overall mixing channel 120 with a = 0.2 mm at y = asin (2πx / λ). ) Height H was set to 0.5 mm (H = 2a + 0.1).

In addition, the first and second inlets 112 and 114 through which different fluids are respectively introduced are 180 degrees apart from each other, and the first and second inlets 112 and 114 are connected to a point where they meet each other. The connecting portion 122 of the mixing channel 120 is formed so that its cross-sectional area forms a square of 0.1 mm × 0.1 mm so as to be connected to the first and second inlets 112 and 114 to be perpendicular to the first and second inlets ( 112, 114 and the connecting portion 122 of the mixing channel 120 is to be connected in a T-shape.

)는 0.1mm, 혼합부(124)의 길이(

)는 4.48mm, 배출구(130)의 길이(

)는 1.8mm가 되도록 구성하였다.And, the length of the connecting portion 122 of the mixed channel (120)

) Is 0.1mm, the length of the mixing section 124 (

) Is 4.48 mm, the length of the outlet 130 (

) Was configured to be 1.8mm.

In order to evaluate the performance of the invented micromixer 100, numerical analysis on the flow field and fluid mixing was performed. In order to solve the Navier-Stokes equation and continuous equation, the commercial computational fluid dynamics code ANSYS CFX-11.0 was used.

As the boundary condition, the speed was given to the inlet, the static pressure to the outlet, and the sticking condition to the wall. Ethanol and water were selected as the working fluid for mixing.

㎡/s 이다. 혼합채널(120)의 너비가 변함에 따라 속도를 다르게 하였으며, 레이놀즈수는 모든 작동유체를 물로 가정하여 메인채널의 너비를 기준으로 계산하였다.The physical properties at 20 ℃ were used, and the diffusivity of water and ethanol was

M 2 / s. The speed was varied as the width of the mixing channel 120 changed, and Reynolds number was calculated based on the width of the main channel assuming all working fluids were water.

Quantitative analysis of the mixing was performed by calculating the variance of the fluid species in the channel. In order to evaluate the degree of mixing in the micromixer 100, the dispersion of the mass ratio in the cross section perpendicular to the flow direction was defined as follows.

... (1)

... (One)

은 단면 내 격자점 수,

는 격자 i점에서의 질량비,

은 최적 혼합질량비를 나타낸다.In the above formula (1),

Is the number of grid points in the cross section,

Is the mass ratio at grid i,

Represents the optimum mixed mass ratio.

The mixing index M represents the degree of mixing of the fluid in the cross section perpendicular to the flow direction and is defined as follows.

... (2)

... (2)

는 최대분산을 나타내고, 분산은 완전히 혼합되지 않은 유체의 최대값, 완전히 혼합된 유체의 최소값으로부터 얻어진다.In the above formula (2)

Represents the maximum dispersion, and the dispersion is obtained from the maximum value of the fluid that is not completely mixed and the minimum value of the fluid that is completely mixed.

First, as shown in (a), (b) and (c) of FIG. 3, the pitch? Value is 1.12 in y = asin (2πx / λ) shape of the mixing portion 124 having a length of 4.48 mm. After setting so as to be 0.56 and 0.28 mm, the velocity vector of the secondary flows generated at the cross-sectional area at the peak point when water and ethanol are mixed together with Dean number (K) is shown in FIG. , (b) and (c) are shown, respectively.

와 같이 정의되는 것으로, 여기서 Re는 레이놀즈 넘버를 의미하고, d와 R은 각각 피크점에서의 단면 직경과, 피크점에서의 곡률반경을 나타낸다.In this case, Dean Number is

Where Re is Reynolds number, and d and R represent the cross-sectional diameter at the peak point and the radius of curvature at the peak point, respectively.

In FIG. 4, the case where the Reynolds number Re is 1 and 30 is shown on the left and the right.

As shown in FIGS. 3 and 4, as the pitch λ decreases, the radius of curvature at the peak point also decreases, and as the radius of curvature decreases, the Dean number increases and the intensity of the secondary flow increases. have.

In addition, it can be seen that the rotational center of the vortex moves toward the inner wall surface as the pitch λ value, that is, the wavelength decreases.

Therefore, through the above test results, it is confirmed that the mixing performance is improved as the pitch value of the sinusoidal shape, that is, the wavelength is reduced, and the mixing performance is improved as the Reynolds number is higher.

Such test results are shown graphically in FIG. 5. As can be seen in Figure 5, the mixing index (Mixing index) is the highest when the pitch value of λ = 0.28mm, the higher the Reynolds number is improved.

In more detail, the lower the pitch value, that is, the more peaks and valleys in the mixed channel 120 having the same length, the smaller the radius of curvature at the peaks and valleys, the shorter the curved section, and the shorter the curved section, the peak. Secondary flow from the bone and bone becomes stronger and the mixing performance is greatly increased.

In contrast, as shown in FIGS. 3 and 4A, when the pitch value is large, that is, when there are few peaks and valleys in the mixing channel 120 having the same length, the intensity of the secondary flow is weakened. The mixing process is delayed and the mixing index is low.

On the other hand, Figure 6 (a), (b) shows the mixing index according to the shape of the mixing channel 120 having the same fixed x-axis length, Figure 6 (a) is a passive fine mixer according to the present invention The mixed channel 120 (when lambda = 0.28 mm), the mixed channel having a square wave shape, and a mixed channel composed of straight lines are shown.

At this time, the height (H) and pitch (λ) of the square wavelength channel is 0.5mm and 0.28mm, respectively, the same as the sinusoidal mixing channel 120 according to the present invention, the cross section is square, 0.1 mm × 0.1 It had a dimension of mm.

6 (b) shows the mixing index according to the Reynolds number of the three-shaped mixing channel 120, the sinusoidal mixing channel 120 according to the present invention is mixed overall compared to the other two shapes You can see that the index has improved significantly.

That is, generally, a mixed channel having a square wave shape is known to exhibit higher mixing performance than a zigzag mixed channel and a curved mixed channel, and the sinusoidal mixed channel 120 according to the present invention includes the entire region, especially Reynolds. When the number Re is 30 or less, it has a much better mixing performance than the mixing channel having a square wavelength shape.

Therefore, according to the passive micromixer 100 according to the present invention as described above, the mixing channel 120 of the micromixer 100 used to mix two different fluids to form a sine wave shape to fine It is possible to significantly improve the mixing performance of the fluid without lowering the mixing speed of the fluid in the flow path.

Although the preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention.

The present invention relates to a passive type micromixer, and more particularly, the type of the micromixer used for mixing two different fluids to form a sinusoidal shape, so that a simple configuration can achieve a significantly improved mixing performance compared to the conventional To a fine mixer.

100: mixer 110: inlet
112: first inlet 114: second inlet
120: mixed channel 122: connection portion
124: mixing section 130: outlet

Claims (4)

In the passive fine mixer,
Two inlets through which different fluids enter,
A sinusoidal mixing channel connected to the inlet and installed;
It is configured to include an outlet connected to the mixing channel is installed,
The shape of the mixing channel is defined as a sine function of the form y = asin (2πx / λ), passive passive mixer characterized in that it is configured to include five or more peak points.
(A is the amplitude, λ is the pitch or wavelength, x, y is the coordinate value along the horizontal and vertical, respectively.)
The method of claim 1,
The mixing channel is a passive fine mixer, characterized in that consisting of a connecting portion which is connected to the installation point between the two inlets and the mixing portion formed between the connecting portion and the outlet.
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