JP2002346355A - Micro mixer - Google Patents

Abstract

(57) [Problem] To provide a micromixer capable of efficiently mixing a small amount of liquid with a small size and a simple structure, and realizing manufacture with a small number of processing steps. SOLUTION: An etching process is performed on an upper surface side of a cell substrate for a cell 10 in which a cell substrate 11 and a cover 12 are overlapped and joined, and an introduction channel 13, a mixing channel 14, and a mixing channel corresponding to liquids A and B are mixed. In addition to forming the outflow channel 15 for the liquid C, the mixing channel is formed as a flat channel whose channel width is larger than that of the inflow channel and the outflow channel, and on the bottom side of the mixing channel. A plurality of convex constricted portions 15a extending
Are formed, and the liquid A supplied from the inlets 13a and 13b is
B is effectively mixed by a turbulent flow generated in the throttle portion of the mixing channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micromixer for mixing a plurality of kinds of trace liquids supplied from outside.

[0002]

2. Description of the Related Art The micromixer mentioned above is known as a microanalyzer used in the chemical analysis and medical fields, etc., and as a device for mixing a small amount of liquid by applying to quantitative mixing of chemicals. This micromixer reduces the running cost of the instrument by reducing the amount of samples and reagents to be mixed, such as when only a small amount of sample is used for analysis or when the reagents to be mixed are expensive. In order to eliminate this, a device as small as possible and having high mixing performance is required.

[0003] That is, when a liquid having a viscosity of about water flows through a fluid device having a fine flow channel having a flow channel width on the order of several μm to 1 mm, the Reynolds number is 1 to several tens. Since the liquids are extremely small in order, if different kinds of liquids are to be mixed in a laminar flow state in a minute flow path, the liquids are mixed by molecular diffusion through contact surfaces of the respective laminar flows. For example, when two kinds of liquids are supplied so as to have the same concentration at the inlet of the flow channel, and the concentration change at a place away from the inlet while being left at a flow velocity of 0 is estimated from a diffusion equation, the diffusion coefficient of the liquid molecule is obtained. In the case of 1 × 10 ⁻³ , it takes about 10 seconds for the concentration at a point 0.1 mm away from the inlet to become 50% of the inlet concentration.
As described above, it takes a long time to mix liquids that depend on molecular diffusion, so if it is desired to continuously supply and mix different types of liquids from the inlet, the flow path length is increased and the liquid is lengthened. It is necessary to take measures such as prolonging the contact time between them to mix.

Next, C by flow injection method
OD (chemical oxygen demand) measuring device
The configuration is shown in FIG. This measuring device uses reagents from tank 1
(K _TwoCr_TwoO₇) And high pressure pump 2
An injection device 3 for injecting a sample liquid from the injection device and joining it with a reagent;
A thermostat 4 and a state where the sample and the reagent are mixed in the thermostat.
Reaction tube 5 as a mixer and a mixed solution coming out of reaction tube 5
A spectrophotometer 6 for measuring the spectrophotometer of the
You. Here, the reaction tube 5 is formed by coiling a circular tube of φ0.6 mm.
Wound, suitable for mixing and reacting samples and reagents
Mix the entire length of the reaction tube 5 so that sufficient time is secured.
It ranges from several tens of cm to several tens of meters depending on the type of medicine. That
The size of the device is large, and large amounts of samples and reagents are consumed for analysis.
There is a problem that it becomes necessary.

On the other hand, FIG. 5 shows the structure of a micromixer disclosed in Japanese Patent Application Laid-Open No. 9-234462 as a conventional example of a static micromixer which is incorporated in a chemical analyzer to mix a sample and a reagent. In this micromixer, a large number of micro nozzles 9a are pierced in the bottom surface of a concave mixing flow channel 9 formed on the upper surface side of a silicon substrate 8, and provided on the bottom surface of the flow channel when a sample liquid flows through the mixing flow channel 9. The reagent liquid supplied from the back side of the substrate 8 is ejected through the minute nozzle 9a to mix the sample and the reagent in the mixing channel 9. Here, the minute nozzle 9a is, for example, a hole of 0.04 mm square, and the reagent discharged to the mixing passage 9 through the nozzle is mixed with the sample by molecular diffusion. In this configuration,
By increasing the number of nozzles, the contact area between the sample liquid and the reagent liquid is increased, and mixing can be performed in a short time.

[0006]

In the conventional micromixer shown in FIG. 5, the substrate 8 constituting the mixer section has a concave mixing channel 9 and a large number of minute mixing channels on the bottom side of the mixing channel. In order to form the nozzle 9a, it is necessary to perform etching from both the front and back surfaces of the silicon substrate 8, which requires high processing accuracy for positioning the front and back processing surfaces, and a masking process by photolithography. As a result, the number of steps including the etching step increases, and the manufacturing cost increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object a small and simple structure capable of efficiently mixing a small amount of liquid, and the processing of the substrate is performed using a micromachining processing technique. An object of the present invention is to provide a micromixer which can be manufactured by a small number of steps of processing only from one side of the micromixer.

[0008]

According to the present invention, in order to achieve the above-mentioned object, a liquid introduction channel, a mixing channel, and a mixed liquid outflow channel are formed in a cell.
The mixing channel is formed as a flat channel whose channel width is larger than the inlet channel and the outlet channel, and a plurality of throttles are arranged in series to locally narrow the channel cross-section along the channel. It is to be formed (claim 1), and is specifically constructed and processed in the following manner.

(1) The cell is composed of a laminated body in which a cover is overlaid on the cell substrate and the upper surface of the substrate, and the mixing flow path is formed by engraving the upper surface of the cell substrate in a concave shape. A plurality of convex constricted portions extending in a direction crossing the flow path are formed on the bottom side along the path (claim 2). (2) The inlet of the introduction channel and the outlet of the outflow channel are formed so as to be continuous with the introduction channel in the cell and open at the upper surface or front and rear end surfaces of the cell (claim 3).

[0010] In the above configuration, the different kinds of minute liquids (sample liquid and reagent liquid) supplied into the cell from the outside through the inlet merge into the introduction flow path and then enter the mixing flow path having an enlarged flow path width. The mixing by molecular diffusion proceeds while being in contact with each other, and the flow velocity in the flowing direction and the vertical direction is repeatedly changed each time when passing through the convex throttle formed on the bottom side along this mixing flow path. The generated turbulence effectively promotes mixing.

In addition, since each flow path is formed as a concave flow path and a convex throttle portion is formed on the bottom side of the mixing flow path, it is possible to perform engraving on the cell substrate by etching only from one side of the substrate. In the processing step, each flow path and the convex throttle portion can be simultaneously formed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on illustrated embodiments. [Embodiment 1] In FIGS. 1A and 1B, reference numeral 10 denotes a cell (housing) of a micromixer, which includes a cell substrate (silicon substrate) 11 and a cover (glass substrate) 12 bonded to the upper surface of the substrate. An introduction channel 13, a mixing channel 14, and an outflow channel 15 for supplying two liquids to be mixed (for example, a sample liquid and a reagent liquid) are connected in series on the upper surface side of the cell substrate 11 to be described later. Further, at two ends of the cover 12, two inlets 13a and 13b communicating with the introduction passage 13 and an outlet 15a communicating with the outlet passage 15 are opened.

Here, the introduction flow path 13 and the mixing flow path 1
4 and the outflow channel 15 are engraved on the upper surface side of the cell substrate 11 as concave grooves. The mixing channel 14 is formed as a flat channel whose channel width is larger than the front and rear introduction channels 13 and the outflow channel 15.
, The width of the flow path is gradually widened toward the mixing flow path 14 so that stagnation does not occur in the liquid flow. Further, a plurality of convex constricted portions 14a are formed on the bottom side of the mixing channel 14 so as to cross the channel along the longitudinal direction of the channel,
The cross section of the mixing channel 14 is locally narrowed by the throttle portion 14a.

In the above configuration, the inflow ports 13a, 13
The liquids A and B individually supplied from b flow into the mixing flow path 4 after being merged in the introduction flow path 13 and are mixed, and the mixed liquid C flows out of the outflow port 15a through the outflow flow path 15. In this case, a plurality of convex constricted portions 14a are formed on the bottom surface of the mixing channel 14 along the flow channel, so that each time the liquids A and B pass through the constricted portion 14a, the flow direction thereof increases. And the flow velocity changes repeatedly in the vertical direction to produce a turbulent flow, which effectively promotes the mixing of the liquids A and B. In the illustrated example, in order to increase the contact area of the two liquids in the flat mixing channel 14 as much as possible, the opening positions of the inlets 13a and 13b are shifted in the front-rear direction, and the position of the liquid A flowing from the inlet 13a is changed. The liquid B is supplied to the upper surface side from the inflow port 13b so that the two liquids flow in parallel with the bottom surface of the flow path.

Next, a method of manufacturing the above-described micro mixer will be described with reference to FIGS. First, a silicon oxide film 16 is formed on both front and back surfaces of a cell substrate (silicon substrate) 11 by thermal oxidation (see FIG. 1A). This silicon oxide film 1
Reference numeral 6 serves as a mask material for engraving the flow paths of introduction, mixing, and outflow into the silicon substrate 11 and the convex constricted portion by etching as described later. Next, a resist 16 is applied on the surface side of the silicon substrate, and a mask corresponding to the above-described shapes of the introduction channel 13, the mixing channel 14, the outflow channel 15, and the convex constricted portion 14a is patterned by photolithography. Form. In this case, the pattern of the aperture portion is set so as to match the crystal orientation (100) of the silicon substrate. Also, the pattern width L of the diaphragm 14a
Is determined from the target depth H of the flow channel, the etching rate α of the crystal orientation (100) plane, and the side etching rate β of the silicon oxide film. That is, the pattern width L satisfying the following expression (1) is determined so that the silicon oxide film 16 serving as the mask of the pattern of the narrowed portion 14a is etched away when the etching is performed to the predetermined flow channel depth H. Keep it.

[0016]

[Formula 1] L> 2Hβ / α (1) In a subsequent step, the silicon oxide film 16 is immersed in buffered hydrofluoric acid to pattern the mask (see FIG. 2 (b)).
Next, the resist 17 is peeled off, and NaOH or TMAH (tetramethylammonium hydroxide), which is a crystalline anisotropic silicon etchant, is heated to about 70 ° C.
Etching is performed by immersion in a heated state. When this anisotropic etching is performed, the side wall of the convex portion serving as the constricted portion becomes a tapered surface of about 55 ° with respect to the substrate surface (see FIG. (C)). In this case, if the convex portion is etched on the vertical side wall, bubbles and foreign substances contained in the liquid flowing therethrough tend to remain at the corners of the vertical wall and hinder the flow. Such inconvenience can be prevented by using anisotropic etching to form the tapered side wall as described above. Further, the silicon oxide film 16 forming the top surface pattern of the narrowed portion 14a is etched while the pattern of the other portion remains because side etching proceeds from both sides (see FIG. 7D), When etching is further continued, the (100) plane of silicon having a high etching rate is exposed, so
The etching proceeds rapidly from the protruding end of the projection a, and consequently, the height h of the projection forming the narrowed portion 14a is the cell substrate 1
1 is lower than the upper surface (see FIG. 7E). That is, the height h of the projection of the aperture portion 14a is determined by the etching time after the mask pattern of the aperture has disappeared. Then, after etching the silicon substrate, the silicon oxide 16 is removed ((f)
See figure).

On the other hand, the cover 12 for sealing the upper surface of the flow path formed on the cell substrate 11 is made of glass containing alkali ions having the same coefficient of thermal expansion as silicon. Through holes serving as 13a, 13b and the discharge port 15a are formed by a method such as machining or sand blasting. Then, after cleaning the silicon substrate and the glass plate to remove particles attached to the surface of the substrate, the silicon substrate and the glass plate are overlapped and heated to about 400 ° C., and a DC voltage of −400 V is applied to the glass plate. Apply and apply anodic bonding (see figure (g)). Finally, the liquid inlets 13a, 13b and outlet 15 of the cell
A connection port for piping is attached to a to complete the micromixer.

[Embodiment 2] Next, FIGS. 2A and 2B show the configuration of an application embodiment of the present invention. That is, in a mixer device in which various types of liquids are simultaneously mixed using a plurality of micromixers, the occupied space is reduced by vertically stacking the respective micromixers, thereby contributing to downsizing of the entire device.

Therefore, in this embodiment, as shown in FIG. 2, the inlets 13a and 13b for the liquids A and B and the outlet 15a for the mixed liquid C are opened at the front and rear end faces of the cell 10, and the cells are turned up and down. It is designed to be superimposed and laminated. Further, in the illustrated configuration, a step is set between the inlets 13a and 13b, and the liquid B flowing from the inlet 13b flows on the upper surface side of the liquid A flowing from the inlet 13a so that the liquids A and B To increase the contact area.

Although the embodiments of FIGS. 1 and 2 illustrate a two-liquid mixing micromixer for mixing two types of liquids A and B, the number of liquid inlets may be increased with a similar cell configuration. Accordingly, it is possible to configure a micromixer in which three or more types of liquids are mixed.

[0021]

As described above, according to the micromixer of the present invention, the introduction channel, the mixing channel, and the outflow channel corresponding to each liquid are formed in the cell, and the mixing channel is formed. By making the width of the flow passage a flat flow passage that is larger than the introduction flow passage and the outflow flow passage, and by forming a series of multiple throttles that narrow the cross-section of the flow passage locally along the flow passage Can effectively and quickly mix multiple types of liquids supplied from the outside in a minute mixing channel formed in the cell, miniaturizing the chemical analyzer, reducing the consumption of samples and reagents, and analyzing Can be speeded up.

Further, the cell is constituted by a laminated body in which a cover is overlaid on a cell substrate and an upper surface of the substrate, and the mixing flow path is formed by engraving a concave shape on the upper surface side of the cell substrate. By forming a plurality of convex constricted portions extending in the direction crossing the flow path on the bottom side along the path, the cell substrate (silicon substrate) can be etched only from one side thereof. Each flow path and the convex constricted portion can be formed, thereby realizing production in a simple process.

[Brief description of the drawings]

FIGS. 1A and 1B are configuration diagrams of a micromixer corresponding to a first embodiment of the present invention, wherein FIG. 1A is a plan view of a cell substrate, and FIG.

FIGS. 2A and 2B are configuration diagrams of a micromixer corresponding to a second embodiment of the present invention, wherein FIG. 2A is a plan view of a cell substrate, and FIG.

FIGS. 3A and 3B are process diagrams of the micromixer of FIG.
(g) is a diagram showing the processing state in the process order

FIG. 4 is a configuration diagram of a conventional chemical analyzer.

FIG. 5 is a cell configuration diagram of a conventional micromixer.

[Explanation of symbols]

 10 cell 11 cell substrate 12 cover 13 introduction channel 13a. 13b Inflow port 14 Mixing channel 14a Convex throttle 15 Outflow channel 15a Outlet A, B Liquid C Mixed liquid

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01N 37/00 101 G01N 35/06 J

Claims (3)

[Claims] 1. A micromixer for mixing and taking out a plurality of kinds of trace liquids supplied from outside, wherein a liquid introduction channel, a mixing channel, and a mixed liquid outflow channel are formed in a cell. The mixing channel is formed as a flat channel whose channel width is larger than the inlet channel and the outlet channel, and a plurality of throttles are arranged in series to locally narrow the channel cross-section along the channel. A micromixer characterized by being formed. 2. The micromixer according to claim 1, wherein
The cell is constituted by a laminated body in which a cover is overlapped on the upper surface of the cell substrate and the substrate, and the mixing channel is formed by engraving a concave shape on the upper surface side of the cell substrate, and the bottom surface is formed along the mixing channel. A micromixer characterized in that a plurality of convex throttle portions extending in a direction crossing the flow path are formed on the side. 3. The micro mixer according to claim 1, wherein
A micromixer characterized in that an inlet of an introduction flow path and an outlet of an outflow flow path are connected to the introduction flow path in the cell and open at the upper surface or front and rear end surfaces of the cell.