Abstract:
A micro fluidic device is provided, the micro fluidic device including: at least one first introduction pipe into which first fluid is introduced; at least one second introduction pipe into which second fluid is introduced, the second introduction pipe being disposed adjacent to the first introduction pipe; a common channel connected to the first introduction pipe and the second introduction pipe, wherein in the common channel the first fluid and the second fluid are mixed; and a first group of rectification parts, the rectification parts of the first group being provided individually for the first introduction pipe or the second introduction pipe and generating a helical flow in the first fluid and the second fluid, wherein the helical flow in the first fluid and the helical flow in the second fluid have a same circumferential direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 U.S.C. 119 from Japanese Patent Application No. 2009-063109 filed Mar. 16, 2009. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a micro fluidic device and a fluid control method. 
     2. Related Art 
     There have hitherto been known micro fluidic devices for allowing plural fluids to pass as a laminar flow through a micro channel having a diameter of, for example, not more than 0.5 mm, mixing those fluids by means of molecular diffusion and subjecting the mixture to a compound reaction. 
     SUMMARY 
     According to an aspect of the present invention, there is provided a micro fluidic device including: 
     at least one first introduction pipe into which first fluid is introduced; 
     at least one second introduction pipe into which second fluid is introduced, the second introduction pipe being disposed adjacent to the first introduction pipe; 
     a common channel connected to the first introduction pipe and the second introduction pipe, wherein in the common channel the first fluid and the second fluid are mixed; and 
     a first group of rectification parts, the rectification parts of the first group being provided individually for the first introduction pipe or the second introduction pipe and generating a helical flow in the first fluid and the second fluid, 
     wherein the helical flow in the first fluid and the helical flow in the second fluid have a same circumferential direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a perspective view showing an example of the whole configuration of a micro fluidic device according to a first exemplary embodiment of the invention; 
         FIG. 2  is a sectional view along an A-A line in  FIG. 1 ; 
         FIG. 3  is a side view showing the whole of a rectification unit in a fluid branch part seen from a common channel side of  FIG. 2 ; 
         FIGS. 4A and 4B  each shows one rectification part in  FIG. 3 , in which  FIG. 4A  is a front view, and  FIG. 4B  is a sectional view along a B-B line in  FIG. 4A ; 
         FIG. 5  is a plan view showing a configuration of a donor substrate which is used for the manufacture of a micro fluidic device according to a first exemplary embodiment of the invention; 
         FIGS. 6A to 6F  are each a view showing manufacturing steps of a micro fluidic device according to a first exemplary embodiment of the invention; 
         FIGS. 7A to 7C  are each a view showing flows of a first fluid and a second fluid in a liquid branch part of a micro fluid device according to a first exemplary embodiment of the invention; 
         FIG. 8  is a sectional view showing a micro fluidic device according to a second exemplary embodiment of the invention; 
         FIG. 9  is a sectional view along a C-C line in  FIG. 8  as seen form a common channel (outlet) side of  FIG. 8 ; 
         FIG. 10  is a view showing rectification units disposed along a common channel; 
         FIG. 11  is a view showing a part of the rectification units  30 A and  30 B of  FIG. 10  toward x-direction of  FIG. 10 ; 
         FIG. 12  is a sectional view along a D-D line in  FIG. 8  as seen form a common channel (outlet) side of  FIG. 8 ; 
         FIG. 13  is a view showing a positional relationship between rectification parts of the rectification unit  30 A and rectification parts of the rectification unit  30 B shown in  FIG. 10 ; and 
         FIG. 14  is an example of side view showing a micro fluidic device according to a third exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     [First Exemplary Embodiment] 
       FIG. 1  is a perspective view showing an example of the whole configuration of a micro fluidic device according to a first exemplary embodiment of the invention; and  FIG. 2  is a sectional view along an A-A line in  FIG. 1 . 
     This micro fluid device  1  is configured to include a fluid branch part  10  for generating a helical flow in each of introduced first fluid L 1  and second fluid L 2  and discharging them; and a common channel  11  for allowing the first fluid L 1  and the second fluid L 2  discharged from the fluid branch part  10  to pass therethrough. The first fluid L 1  and the second fluid L 2  are each, for example, a liquid, a powder, a gas or the like. 
     The micro fluid device  1  is one kind of a micro fluid apparatus for carrying out a chemical reaction between the first fluid L 1  and the second fluid L 2  within the common channel  11 . This micro fluid apparatus includes, for example, a micro mixer or a micro reactor for merely mixing the first fluid L 1  and the second fluid L 2  within the common channel  11  or regulating the particle size of a powder, etc., or the like. 
     The common channel  11  is made of a metal (for example, Al, Ni, Cu, etc.) or a non-metal (for example, ceramics, silicon, dielectrics, etc.). The common channel  11  has a function to mix the first fluid L 1  and the second fluid L 2  having been discharged from a rectification unit  20  as shown in  FIG. 2  and discharge the thus obtained mixture L 3  from an outlet  110 . 
     (Configuration of Rectification Part) 
       FIG. 3  is a side view showing the whole of the rectification unit seen from a common channel side of  FIG. 2 . The rectification unit  20  is composed of rectification parts  4   a  to  4   p  (hereinafter also referred to as “rectification part  4 ”) having the same configuration, which generate a helical flow in the first fluid L 1  and the second fluid L 2  for every first introduction pipe  2  and second introduction pipe  3 , and these are arranged at regular intervals on the same plane in a manner of 4 lines and 4 rows. The first introduction pipe  2  is connected to each of the rectification parts  4   a ,  4   c ,  4   f ,  4   h ,  4   i ,  4   k ,  4   n  and  4   p ; and the second introduction pipe  3  is connected to each of the rectification parts  4   b ,  4   d ,  4   e ,  4   g ,  4   j ,  4   l ,  4   m  and  4   o . The rectification parts  4   a  to  4   p  are not limited to this number, but the number may be arbitrarily chosen depending upon an application or the like. 
       FIGS. 4A and 4B  each shows one rectification part in  FIG. 3 , in which  FIG. 4A  is a front view, and  FIG. 43  is a sectional view along a B-B line in  FIG. 4A . As described previously, the rectification parts  4   a  to  4   p  have the same configuration. Then, the configuration of the rectification part  4   a  is herein described with reference to  FIGS. 4A and 4B . The rectification part  4   a  is composed of a laminate of plural rectifier plates  40  each having a cross-shaped part  41  and a ring part  42  and provided in an outlet part of the first introduction pipe  2 . 
     (Configuration of Donor Substrate which is Used for the Manufacture of Micro Fluidic Device) 
       FIG. 5  is a plan view showing a configuration of a donor substrate  100  which is used for the manufacture of a micro fluidic device. The rectification unit  20  is manufactured as follows. First all, a metallic substrate  101  made of a metal such as stainless steel is prepared, and a thick photoresist is coated on the metallic substrate  101 . Subsequently, the coated surface of the thick photoresist is exposed through a photomask corresponding to each sectional shape of the micro fluidic device  1  to be fabricated, and the photoresist is developed to form a resist pattern in which positive-negative inversion of each sectional shape has taken place. Subsequently, the metallic substrate  101  having this resist pattern is dipped in a plating bath, thereby growing nickel plating on the surface of the metallic substrate  101  which is not covered by the photoresist. 
     Subsequently, by removing each resist pattern of the metallic substrate  101 , a plural number (M) of thin film patterns  102   1 ,  102   2 , . . .  102   M  (hereinafter also referred to as “thin film pattern  102 ”) are formed on the metallic substrate  101  corresponding to the respective sectional shapes of the rectification unit  20 . Patterns for plural rectifier plates  40  (see  FIGS. 4A and 4B ) are formed on each thin film pattern. The plural thin film patterns are laminated to compose the plural rectification parts  4 . 
     Each thin film pattern  102  on the metallic substrate  101  forms plural patterns each of which is a portion corresponding to the rectifier plate  40 . The thin film pattern  102  is laminated by procedures shown in  FIGS. 6A to 6F  as described below, thereby fabricating the rectification unit  20 . 
     (Manufacturing Method of Rectification Part) 
       FIGS. 6A to 6F  are each a view showing manufacturing steps of the rectification unit  20 . Here, the lamination of the thin film patterns is carried out by means of room temperature bonding. The “room temperature bonding” as referred to herein means direct bonding of atoms to each other at room temperature. First of all, as shown in  FIG. 6A , a donor substrate (first substrate)  100  is disposed on a non-illustrated lower stage within a vacuum tank, and a target substrate (second substrate)  200  is disposed on a non-illustrated upper stage within the vacuum tank. Subsequently, the inside of the vacuum tank is evacuated to a high vacuum state or a super-high vacuum state. Subsequently, the lower stage is relatively moved against the upper stage, thereby locating the thin film pattern  102   1  of the donor substrate  100  just under the target substrate  200 . Subsequently, the surface of the target substrate  200  and the surface of the thin film pattern  102   1  of the donor substrate  100  are cleaned upon irradiation with an argon atom beam. 
     Subsequently, as shown in  FIG. 6B , the target substrate  200  is descended by the upper stage, and the target substrate  200  is pressed against the donor substrate  100  under a previously determined load force (for example, 10 kgf/cm 2 ) for a previously determined period of time (for example, 5 minutes), thereby subjecting the target substrate  200  and the thin film pattern  102   1  to room temperature bonding to each other. 
     Subsequently, as shown in  FIG. 6C , when the target substrate  200  is ascended by the upper stage, the thin film pattern  102   1  is separated from the metallic substrate  101 , whereby the thin film pattern  102   1  is transferred onto the side of the target substrate  200 . This is because a bonding force between the thin film pattern  102   1  and the target substrate  200  is larger than a bonding force between the thin film pattern  102   1  and the metallic plate  101 . 
     Subsequently, as shown in  FIG. 6D , the donor substrate  100  is moved toward an arrow direction by the lower stage, thereby locating the second layer thin film pattern  102   2  on the donor substrate  100  just under the target substrate  200 . Subsequently, the surface of the thin film pattern  102   1  having been transferred onto the side of the target substrate  200  (the surface coming into contact with the metallic substrate  101 ) and the surface of the second layer thin film pattern  102   2  are cleaned in the manner as described previously. 
     Subsequently, as shown in  FIG. 6E , the target substrate  200  is descended by the upper stage, thereby bonding the thin film pattern  102   1  on the side of the target substrate  200  and the thin film pattern  102   2  to each other. Subsequently, as shown in  FIG. 6F , when the target substrate  200  is ascended by the upper stage, the thin film pattern  102   2  is separated from the metallic substrate  101  and transferred onto the side of the target substrate  200 . Thereafter, all of the thin film patterns  102   3  to  102   M  are transferred onto the target substrate  200  from the donor substrate  100  in the same manner. 
     By successively repeating registration between the donor substrate  100  and the target substrate  200 , bonding and isolation in the foregoing manner, the plural thin film patterns  102  corresponding to the respective sectional shapes of the rectification unit  20  are transferred onto the target substrate  200 . The target substrate  200  is removed from the upper stage, and the transferred laminate on the target substrate  200  is separated from the target substrate  200 , whereby the rectification parts  4   a  to  4   p  are collectively fabricated. 
     The rectification parts  4   a  to  4   p  may also be fabricated by a semi-conductor process. For example, a substrate made of an Si wafer is prepared; a mold releasing layer made of a polyimide is formed on this substrate by a spin coating method; an Al thin film serving as a material of the rectifier plate is formed on the surface of this mold releasing layer by a sputtering method; and the Al thin film is subjected to sputtering by a photolithography method, thereby fabricating the donor substrate. 
     (Flow of Fluid in Rectification Part) 
       FIGS. 7A ,  7 B and  7 C are each a view showing flows of the first fluid and the second fluid in the liquid branch part of the micro fluid device. The first fluid L 1  is introduced into the first introduction pipe  2  of each of the rectification parts  4   a ,  4   c ,  4   f ,  4   h ,  4   i ,  4   k ,  4   n  and  4   p ; and the second fluid L 2  is introduced into the second introduction pipe  3  of each of the rectification parts  4   b ,  4   d ,  4   e ,  4   g ,  4   j ,  41 ,  4   m  and  4   o . Here, in case of the present exemplary embodiment, the first fluid L 1  and the second fluid L 2  include a fine particle (for example, a toner). 
     In passing through the rectification parts  4   a  to  4   p , the first fluid L 1  and the second fluid L 2  are each rotated in a helical form by the rectifier plate  40 . At outlets of the rectification parts  4   a  to  4   p , all of a helical flow F 1  of the first fluid L 1  and a helical flow F 2  of the second fluid L 2  are generated in the same direction (here, in a counterclockwise direction) as shown in  FIG. 7A . 
     In the first fluid L 1  and the second fluid L 2  immediately after coming out the rectification parts  4   a  to  7   p , since a barrier for partitioning them from each other is not provided, the helical flow F 1  and the helical flow F 2  which are generated corresponding to each of the rectification parts  4   a  to  4   p  are in a state of coming into contact with each other as shown in  FIG. 7B . For example, as shown in  FIG. 7C , the helical flow F 1  which has come out the rectification part  4   a  and the helical flow F 2  which has come out the rectification part  4   b  flow in a reverse direction to each other at an interface R of the both. Accordingly, a shear force is generated between the first fluid L 1  and the second fluid L 2  at the interface R, and when a shear force is applied to the first fluid L 1  and the second fluid L 2  and also to fine particles included therein, it becomes easy to control the size and distribution of fine particles which are discharged from the outlet  110 . 
     Thereafter, the first fluid L 1  and the second fluid L 2  advance within the common channel  11  and mix, and the mixture L 3  is then discharged from the outlet  110 . 
     In the foregoing exemplary embodiment, though only the rectification part is formed by laminating the thin film pattern, the rectification part and a portion of the main body part in the surroundings thereof may be formed by laminating the thin film pattern. 
     [Second Exemplary Embodiment] 
       FIG. 8  is a sectional view showing a micro fluidic device according to a second exemplary embodiment of the invention;  FIG. 9  is a sectional view along a C-C line in  FIG. 8  as seen form a common channel (outlet) side of  FIG. 8 ; and  FIG. 12  is a sectional view along a D-D line in  FIG. 8  as seen form a common channel (outlet) side of  FIG. 8 . In  FIGS. 9 and 10 , illustration of the rectifier plate  40  in each of rectification parts  6  and  7  is omitted. 
     In the present exemplary embodiment, rectification units  30 A,  30 B,  30 C and  30 D are arranged at fixed intervals in the flow direction of a fluid in place of the rectification unit  20  in the first exemplary embodiment shown in  FIG. 2 . The number of the rectification units  30 A to  30 D is to this four, but the number may be arbitrarily chosen. 
     The rectification units  30 A and  30 C each has a configuration shown in  FIG. 9 , and the rectification units  30 B and  30 D each has a configuration shown in  FIG. 12 . Each of the rectification units  30 A to  30 D is composed of five rows of rectification parts, and a single row is composed of five rectification parts  6  and one rectification part  7 . The rectification unit  30 A is provided with plural rectification parts  6  having the same structure and outer diameter of the rectifier plates  40  as in the rectification parts  4   a  to  4   p  and plural rectification parts  7  in which the structure of the rectifier plates  40  is the same, and the outer diameter thereof is substantially ½ of the rectification part  6 . 
     As shown in  FIG. 9 , in the rectification units  30 A and  30 C, the rectification part  7  is disposed on the uppermost end of the five rectification parts  6  in a first row (row of the left-sided end); and the rectification part  7  is disposed on the lowermost end of the five rectification parts  6  in a second row (second row from the left side). Furthermore, a third row (center) and a fifth row (row of the right-sided end) have the same arrangement as the first row; and a fourth row has the same arrangement as the second row. By taking such a configuration, the adjacent rectification parts  6  are disposed in a close contact state with each other. The first introduction pipe  2  and the second introduction pipe  3  are connected to each of the rectification parts  6  of the rectification unit  30 A, and a third introduction pipe  5  is connected to the rectification part  7 . 
       FIG. 10  is a view showing rectification units disposed along a common channel. The rectification units  30 A and  30 B are disposed along the common channel in the direction of x shown in  FIG. 10  (in an axis direction of the common channel) at a predetermined distance. In  FIG. 10 , rectification unit  30 A is disposed as a former rectification unit and the rectification unit  30 B is disposed as a latter rectification unit. The rectification parts  6  and  7  each of which belongs to the rectification unit  30 A or  30 B are arranged along a plane parallel to y-z plane shown in  FIG. 10 . The rectification parts  6  and  7  belonging to the rectification unit  30 A (for example,  6 A shown in  FIG. 10 ) have center lines q (illustrated by dashed line in  FIG. 10 ) which are parallel to x direction. In the same manner, the rectification parts  6  and  7  belonging to the rectification unit  30 B (for example,  6 B shown in  FIG. 10 ) have center lines r (illustrated by dashed-two dotted line in  FIG. 10 ) which are parallel to x direction. The center lines q and r described here are lines each passing through the center of the ring part  42  (See  FIG. 4A ) of the rectification part  6  or  7 . 
       FIG. 11  is a view showing a part of the rectification units  30 A and  30 B of  FIG. 10  toward x-direction of  FIG. 10 . In  FIG. 11 , the rectification part  6 B of the latter rectification unit  30 B is illustrated by dotted lines. Dots r and q shown in  FIG. 11  correspond to the center lines r and q in  FIG. 10 , respectively. 
     The positions of the center lines q of the rectification parts  6  and  7  belonging to the rectification unit  30 A are out of alignment with the center lines r of the rectification parts  6  and  7  belonging to the rectification unit  30 B. In other wards, the center lines q do not overlap with the center lines r. 
     The above explanation is not limited to the arrangements of the rectification parts of the rectification units  30 A and  30 B, but is also applied to arrangements of rectification parts of another former rectification unit and another latter rectification unit (for example the arrangements of the rectification parts of the rectification unit  30 B and the rectification unit  30 C, or the like). 
     Also, as shown in  FIG. 12 , in the latter rectification unit ( 30 B and  30 D, for example), the rectification parts  6  and  7  are located upside down with respect to the rectification parts  6  and  7  disposed in each of the rows of the former rectification unit  30 A.  FIG. 13  is a view showing a positional relationship between rectification parts of the rectification unit  30 A and rectification parts of the rectification unit  30 B shown in  FIG. 10 . In  FIG. 13 , a center plane is disposed between the rectification unit  30 A and the rectification unit  30 B, for purpose of illustration. A distance between the center plane and the rectification unit  30 A and a distance between the center plane and the rectification unit  30 B are equidistance L. The center plane intersects a center line of the common channel in the axis direction at a point c. As illustrated with dashed line in  FIG. 13 , the rectification parts  6 B 1 ,  6 B 2 ,  7 B 1  and  7 B 2  (the rectification part  7 B 2  is invisible in  FIG. 13 ) of the latter rectification unit  30 B and the rectification parts  6 A 1 ,  6 A 2 ,  7 A 1  and  7 A 2  of the former rectification unit  30 A are symmetry with respect to the point c. 
     The above explanation is not limited to the arrangements of the rectification parts of the rectification units  30 A and  30 B, but is also applied to arrangements of rectification parts of another former rectification unit and another latter rectification unit (for example the arrangements of the rectification parts of the rectification unit  30 B and the rectification unit  30 C, or the like). 
     Since the action of the present exemplary embodiment is the same as in the first exemplary embodiment, its explanation is omitted. 
     [Other Exemplary Embodiments] 
     The invention is not limited to the foregoing respective exemplary embodiments, and various modifications may be made within the range where the gist of the invention is not changed. For example, a combination of constitutional elements among the respective exemplary embodiments may be arbitrarily made. 
     Also, in the foregoing respective exemplary embodiments, while the configuration where two fluids are mixed has been shown, the two fluids may be the same fluid, or may be a different fluid from each other. Also, there may be adopted a configuration where two or more fluids which are the same or different are mixed. 
     Also, the main body part of the fluid branch part or the common channel may be formed by laminating a thin film pattern. 
     [Third Exemplary Embodiment] 
       FIG. 14  is an example of side view showing a micro fluidic device according to a third exemplary embodiment of the invention. 
     In the foregoing respective exemplary embodiments, while the configuration where a flow is branched in a fluid branch part such that two fluids flow adjacent to each other, and a helical flow is then generated in each of the fluids in a rectification part has been shown, there may be adopted a configuration where a helical flow is generated in advance in each fluid in a rectification part, the flow is then branched in a fluid branch part such that two fluids flow adjacent to each other, and the two fluids are mixed in a merging channel, as shown in  FIG. 14 . 
     The foregoing description of the embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention defined by the following claims and their equivalents.