JP2008212882A - Micromixer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow-channel structure of a static micromixer which makes efficient mixing proceed only with a flow channel form, without the arrangement of a specific stirrer, concerning a fluid-mixing operation for microfluid elements represented by a μTAS (MicroTotal Analysis System), and to provide a manufacturing method thereof. <P>SOLUTION: Either the left side of a posterior-to-confluence flow channel (a main flow channel 1) or its right side is dug deeper than the bottom part of the main flow channel, and a flow channel (a tributary flow channel 2), which is diagonally dug toward the downstream up to the left and right sides of the main flow channel, respectively, is formed to have an adequate form and size. By this, the effect is generated, which makes the fluid section of a fluid, which flows through a flow channel-forming area, elastic, rotatable and overlappable. By repeatedly generating this effect toward the downstream of a mixing flow channel, a layer-to-layer distance between fluid elements is decreased to accelerate the mixing. This is shown in Fig.2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a structure of a mixing operation unit and a manufacturing method thereof in a mixing operation (micromixing) of a microfluid (fluid flowing in a flow path dimension on the order of several μm to several 100 μm).

In recent years, μTAS (μ Total Analysis System) aimed at miniaturization of chemical analyzers, biochemical analyzers, etc. has attracted attention, and its application to gene analysis chips, chemical synthesis chips, biochemical synthesis chips, environmental analysis chips, etc. Expected. When these miniaturizations are realized, the benefits of reducing the amount of samples, reagents, waste liquid, etc., shortening measurement time, reducing power consumption of the entire system, reducing costs, and portability compared to conventional analyzers. A wide variety of research has been conducted because of expectations. One of the components of these analysis systems is a micromixer for performing mixing in a micro area. On the other hand, there are many cases where the Reynolds number is about 200 or less in the micro flow channel (micro channel) because the channel size and flow velocity are both small. When the Reynolds number is small, turbulence hardly occurs in the microchannel, and laminar flow becomes dominant. Therefore, the mixing of the fluid is mainly diffusion mixing at the contact interface between the fluids, and efficient mixing cannot be performed simply by joining them.

In order to perform this mixing efficiently, for example, in Patent Document 1, a spiral protrusion (or in the interior of the flow path is used in the flow path in which oblique irregularities are arranged on the bottom and side surfaces of the micro flow path. A method has been proposed in which a spiral flow of fluids is produced by using a flow path having a convex-concave spiral to increase mixing efficiency. Further, Patent Document 3 describes an improvement in mixing efficiency by introducing fluid from a tributary manufactured separately from the main flow and mixing the chaos.
JP2005-199245 JP 2006-142210 Patent No. 3629575

Only the intermittently formed concave and convex grooves shown in Literature 1 and the concave and convex spiral grooves provided in the main flow shown in Literature 2 cause spiral flow, but the problem of low mixing efficiency There is. Further, the method of Document 3 requires a plurality of tributary flow paths and a fluid control pump, and there is a problem that the size reduction and cost reduction required for an analytical instrument are not achieved.

The present invention has been made in view of the above problems, and an object thereof is to provide a micromixer that is inexpensive and has high mixing efficiency and a method for manufacturing the micromixer.

In order to achieve the above object, the present invention forms another continuous tributary flow channel branched from the main flow channel of the micro flow channel at the lower part of the main flow channel, so that the main flow and the tributary flow are greatly increased in the flow direction. A means for repeating fluid movement alternately is proposed. According to this means, stretching and folding of the flow cross section in the flow direction occur repeatedly, and the distance between the fluid layers decreases exponentially. FIG. 2 shows how the interlayer distance decreases. That is, consider a case where the operations of cross-sectional expansion and contraction and rotation superposition are repeated in the order of 1 to 7 in FIG. Since the effect of the tributary flow path is the same in all cases, it can be considered that the same rotation operation as 1 → 2 is repeated. Here, the operation of 1 → 2 extends 1 colored area vertically and horizontally reduces it, moves to 2 colored areas in parallel, and 1 white area extends vertically and horizontally reduced. Is rotated 180 ° to match the right side of the colored area. As described above, since the interlayer distance becomes 1/2 in one operation, the interlayer distance becomes the original (1/2) ^{n-1 in the nth} . When n = 7, (1/2) ⁶ = 1/64.

In the present invention, since the main flow and the tributary flow are manufactured by mechanical processing means (removal processing or molding processing), a three-dimensional flow path structure with a change in the depth direction can be easily formed in a short time. Can do. Further, the structural change can be easily changed, and the manufacturing cost can be reduced as compared with the manufacturing method using the semiconductor exposure process presented in Patent Document 1.

  In the present invention, the mainstream fluid element is stretched and folded by another branch flow channel branched from the mainstream. By repeating this operation, the interlayer distance of the fluid element is reduced and diffusion is promoted in a short time. The As a result, it is possible to reduce the size of the micromixer.

Hereinafter, the present invention will be specifically described using examples and comparative examples.
In carrying out the mixing operation, the branch flow channel 3 was formed in the lower part of the main flow channel so as to be diverted from the main flow flow channel 1 of the Y mixer with reference to a mixing flow channel called a Y-shaped mixer. Here, the Y-shaped mixer is one in which two types of liquids are introduced from two inlets, merged into one, mixed, and discharged through a mixing portion having a predetermined length. FIG.

The performance evaluation of the mixer is a method in which two types of liquids with different colors (red and white) are made to flow into the two inlets with a syringe pump and the change (rotation) of the color passing through the mixing section is examined (Patent Document) 1) and a method of quantifying the degree of mixing using image numerical data (RGB numerical values). The method of quantifying the numerical image data was performed by normalizing the color data before the mixing portion to values of 0 and 1, and calculating the standard deviation of the image numerical data after mixing. For complete separation, the standard deviation s = 0.5, and for complete mixing, the standard deviation s = 0. The colored solution was prepared by adding 1 g of red and white water-soluble paint to 9 cc of pure water. When the kinematic viscosity coefficient ν of the solution was measured with an Ostwald relative viscometer, it was 1.64 mm ² / s for the white solution and 1.43 mm ² / s for the red solution (average of 1.50 mm ² / s for the Reynolds number calculation). s was used as the kinematic viscosity coefficient).

These solutions were used with a microsyringe pump, and a fluid having a flow rate of 13 mm ³ / min was introduced into each of the fluid inflow channels 2 so that the total flow rate of fluid flowing through the main flow channel 1 was 26 mm ³ / min. When this flow rate is calculated from the flow path dimensions of the micromixer, the average flow velocity is about 43 mm / s at a width of 200 μm and a depth of 50 μm, and is 21.6 mm / s at a flow path of 200 μm width and 100 μm depth. In this case, the Reynolds numbers are 3.9 and 3.2, respectively. However, the representative channel dimensions are 133 μm and 80 μm, respectively.

The mixing effect (quantification of color mixing and the degree of rotation) of the tributary channel 3 branched from the main channel 1 was examined. The tributary flow paths were formed by cutting at the lower part of the main flow, and 20 (pitch was 0.5 mm) tributary flow paths were formed between 2 mm from the junction of the Y-shaped mixer and 10 mm. The red and white solution described above was allowed to flow through this mixer at a constant flow rate of 26 mm ³ / min. In addition, the combined effect of the main flow and the tributary, and the respective channel depths was investigated. Table 1 shows a combination experiment of the channel depth Md of the main channel and the channel depth Sd of the branch channel.
Table 1. Combination experiment table of mainstream channel depth Md and tributary channel depth Sd

FIG. 3 shows the degree of mixing in the combination of the main flow channel depth and the tributary channel depth. As seen in the figure, the combination of Md = 50 μm and Sd = 100 μm is the most mixed. Furthermore, considering the main flow channel width of 200 μm and the tributary flow channel width of 100 μm, when the main flow channel cross-sectional area Sm and the tributary flow channel cross-sectional area Ss are evaluated, mixing is appropriate when Sm / Ss ≦ 1.

(Comparative Example 1)
In the comparative example 1, it is a Y-shaped mixer which does not provide a tributary flow path. The channel width is 200 μm and the depth is 50 μm.

(Comparative Example 2)
Comparative Example 2 is a micromixer disclosed in Patent Document 1 (Example 1).

(Evaluation)
FIG. 4 shows the mixing state under the condition of Md = 50 μm Sd = 100 μm. The Y-shaped mixer is also shown. The flow path length required for the upper and lower interchange (0.5 rotation) is 1.0 mm. Note that the Y-shaped mixer in Comparative Example 1 does not rotate.

In Comparative Example 2, since the rotation is 14 mm and 2 rotations (Example 1 of Patent Document 1), the length required for 0.5 rotation can be calculated as 3.5 mm. It can be seen that this requires 3.5 times as long as 1.0 mm of the present invention.

From the above, it can be seen that the tributary flow channel formed separately from the main flow flow channel is effective for mixing the microfluids.

In addition to the basic performance of high mixing efficiency, the present invention has a simple structure and can be manufactured at low cost, so it can be widely applied to medical diagnostic analyzers, pharmaceutical manufacturing equipment, and chemical analyzers. is there.

It is the schematic plan view which shows an example of the micromixer (what provided the branch flow path to the Y-shaped mixer) of this invention, and the schematic structure figure of a branch flow path. It is a figure which shows the mixing mechanism by repetition of conversion of a flow cross section. FIG. 3 is a diagram showing the degree of mixing (standard deviation) in Example 1. It is a figure which shows the flow condition in Example 1 and Comparative Example 1 (Y-shaped mixer which does not provide a tributary flow path).

Explanation of symbols

1. 1. Main flow path 2. Inlet channel 3. Tributary flow path Chamfered part

Claims (4)

In a concave channel that joins and mixes a plurality of channels manufactured on a flat plate, dig deeper into the left and right sides of the channel after the merge (mainstream channel 1) deeper than the bottom of the mainstream channel. The micromixer is characterized in that a flow channel (branch flow channel 2) is formed by digging obliquely to the left and right sides of the main flow channel. A micromixer characterized in that Sm / Ss ≦ 1 when the cross section of the flow path formed on the flat plate is a main flow path cross section Sm and a tributary flow path cross section Ss. A micromixer characterized in that a chamfering region for reducing flow resistance is provided in each of a branch region from the main flow channel to a branch flow channel and a merge region from the branch flow channel to the main flow. These corners of the main flow channel, tributary flow channel, branch region and merge region are mechanically removed (cutting, grinding), molding by tool / die press, mold injection molding, or a combination of these processes. The manufacturing method of the micromixer characterized by the above-mentioned.

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