Abstract:
A microchannel chip, includes: a first channel where a first liquid is transported from one end side to an opposite end side; a port section to which a second liquid is supplied from outside for accumulating the second liquid; and a second channel connecting the first channel and the port section through a first opening provided in a side of the first channel and a second opening provided in the port section, wherein the second channel checks flowing out of the second liquid accumulated in the port section to the first channel by a Laplace pressure valve until the first liquid arrives at the first opening, and the second channel converges the second liquid into the first liquid after the first liquid reaches the first opening, and a converging device using the same.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a microchannel chip for mixing two liquids and a converging device capable of mixing a predetermined quantity of a second liquid with a predetermined quantity of a first liquid without involving an air bubble. 
         [0003]    2. Description of the Related Art 
         [0004]    To mix a second liquid with a first liquid, first, the second liquid needs to be converged with the first liquid. For example, using a channel  1  shaped like a letter Y shown in  FIG. 10 , the first liquid is allowed to flow into a first branch channel  2  and the second liquid is allowed to flow into a second branch channel  3 , whereby the first liquid and the second liquid can be mixed with each other in a converging channel  4 . 
         [0005]    In the channel  1  shown in  FIG. 10 , however, when the second liquid is allowed to flow into the second branch channel  3  after the first liquid is allowed to flow into the converging channel  4  from the first branch channel  2  as shown in  FIG. 11A , an air bubble  5  is entered between the leading face of the second liquid in the second branch channel  3  and the first liquid as shown in  FIG. 11B  and a defective condition that the air bubble  5  mixes in the post-mixed two liquids as shown in  FIG. 11C  occurs. 
         [0006]    If the supply start timings of the first liquid and the second liquid are controlled so that the timing at which the first liquid arrives at the converging channel  4  from the first branch channel  2  and the timing at which the second liquid arrives at the converging channel  4  from the second branch channel  3  become the same, mixing of an air bubble does not occur. In fact, however, it is difficult to control the arrival timings as the same timing and mixing of an air bubble cannot be circumvented. 
         [0007]    Then, hitherto a Laplace pressure valve has been used as shown in JP-A-2004-157097, JP-A-2004-225912 and JP-A-2002-527250. When the Laplace pressure valve is described using the channel  1  in  FIG. 10 , it refers to a phenomenon in which when the second liquid is introduced into the second branch channel  3 , the second liquid is checked due to a Laplace pressure difference in the connection end face portion to the converging channel  4  if the capillary force of the second branch channel  3  is previously made large as compared with the capillary force of the first branch channel  2  and that of the converging channel  4  (for example, the capillary force can be made large by thinning the pipe line). 
         [0008]    In this state, when the first liquid is allowed to flow into the converging channel  4  from the first branch channel  2  and reaches the connection end face portion and wets the end face of the second liquid, the Laplace pressure valve is “opened,” preventing an air bubble from being sandwiched between the first liquid and the second liquid when the liquids mix. 
       SUMMARY OF THE INVENTION 
       [0009]    To mix two liquids with each other, mixing of an air bubble can be circumvented by using the Laplace pressure valve. However, each of the microchannel chips described in JP-A-2004-225912 and JP-A-2002-527250 has a basic configuration wherein one liquid is branched into two channels and one is checked by the Laplace pressure valve before they are mixed. Therefore, to mix two liquids according to this method, although two liquids of continuous flows can be converged, it is difficult to mix two liquids each having a given quantity. Withstand pressure p of the Laplace pressure valve generally is represented as p=2 γ cos θ/r. To mix two liquids each having a given quantity with each other, it is necessary to check liquid A of a given quantity by the Laplace pressure valve and transport liquid B of a given quantity by air pressure or a centrifugal force. At this time, if the same pressure also acts on the Laplace pressure valve and exceeds the withstand pressure of the valve, the valve is opened before the liquids mix, and an air layer is produced between the liquids A and B and the liquids cannot mix. In the microchannel chip in JP-A-2004-157097, liquid is handled quantitatively and thus an atmospheric release part is provided in a channel, it is feared that some of the liquid transported under pressure may leak out from the atmospheric release part to the outside, and it is difficult to stably mix two liquids each having a fixed quantity with each other. 
         [0010]    It is an object of the invention to provide a microchannel chip for mixing two liquids and a converging device capable of stably mixing two liquids each having a given quantity with each other as mixing of an air bubble is circumvented. 
         [0011]    (1) A microchannel chip, comprising: 
         [0012]    a first channel where a first liquid of a first quantity is transported from one end side to an opposite end side; 
         [0013]    a port section having a capillary force smaller than a capillary force of the first channel, the port section to which a second liquid of a given quantity is supplied from outside for accumulating the second liquid; and 
         [0014]    a second channel having a capillary force larger than the capillary force of the first channel, the second channel connecting the first channel and the port section through a first opening provided in a side of the first channel and a second opening provided in the port section, 
         [0015]    wherein the second channel checks flowing out of the second liquid accumulated in the port section to the first channel by a Laplace pressure valve until the first liquid arrives at the first opening, and 
         [0016]    the second channel converges the second liquid of a second quantity resulting from subtracting a volume of the second channel from the given quantity into the first liquid of the first quantity after the first liquid reaches the first opening. 
         [0017]    (2) The microchannel chip as described in (1) above, 
         [0018]    wherein a plurality of pairs of the port sections and the second channels are apposed along the first channel. 
         [0019]    (3) A converging device, comprising: 
         [0020]    the microchannel chip as described in (1) or (2) above; and 
         [0021]    a decompression unit that applies a decompression force to the opposite end side of the first channel for transporting the first liquid under decompression to the opposite end side. 
         [0022]    (4) A converging device, comprising: 
         [0023]    the microchannel chip as described in (1) above; 
         [0024]    a decompression unit that applies a decompression force to the opposite end side of the first channel for transporting the first liquid under decompression to the opposite end side; and 
         [0025]    a valve unit provided between the decompression unit and the port section, the valve unit allowing the decompression unit to also apply the decompression force to the port section until the first liquid arrives at the first opening, and releasing the port section into atmosphere after the first liquid arrives at the first opening. 
         [0026]    (5) A converging device, comprising: 
         [0027]    the microchannel chip as described in (2) above; 
         [0028]    a decompression unit that applies a decompression force to the opposite end side of the first channel for transporting the first liquid under decompression to the opposite end side; and 
         [0029]    a plurality of valve units each provided between the decompression unit and each of the port sections, the plurality of valve units each allowing the decompression unit to also apply the decompression force to the corresponding port section until the first liquid arrives at the first opening for each of the pairs, and releasing the corresponding port section into atmosphere after the first liquid arrives at the first opening. 
         [0030]    (6) A converging device, comprising: 
         [0031]    the microchannel chip as described in (1) above; 
         [0032]    a compression and decompression unit that compresses the first liquid from the one end side for transporting the first liquid under compression until the first liquid arrives at the first opening, stops the compression after the first liquid arrives at the first opening, and applies a decompression force to the opposite end side for transporting the first liquid under decompression; and 
         [0033]    a valve unit that performs route switching of the compression force and the decompression force made by the compression and decompression unit. 
         [0034]    (7) The converging device as described in any of (4) to (6) above, further comprising: 
         [0035]    a sensor that detects the first liquid arriving at the first opening. 
         [0036]    (8) The converging device as described in (7) above, 
         [0037]    wherein the valve unit is subjected to automatic switching control according to a detection signal of the sensor. 
         [0038]    The invention makes it possible to stably mix two liquids each having a given quantity with each other as mixing of an air bubble is circumvented. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]      FIG. 1  is a top view of a microchannel chip for mixing two liquids according to a first embodiment of the invention; 
           [0040]      FIG. 2  is a sectional view taken on line II-II in  FIG. 1 ; 
           [0041]      FIG. 3  is a sectional view taken on line III-III in  FIG. 1 ; 
           [0042]      FIGS. 4A and 4B  are drawings to show the initial state when two liquids are converged with each other in the microchannel chip for mixing two liquids according to the embodiment of the invention shown in  FIG. 1 ; 
           [0043]      FIGS. 5A to 5C  are schematic representations to show the process of converging two liquids from the state in  FIGS. 4A and 4B ; 
           [0044]      FIG. 6  is a drawing of the configuration of a converging device for mixing two liquids according to a second embodiment of the invention; 
           [0045]      FIG. 7  is a flowchart to show an operation procedure of the converging device for mixing two liquids shown in  FIG. 6 ; 
           [0046]      FIG. 8  is a drawing of the configuration of a converging device for mixing two liquids according to a third embodiment of the invention; 
           [0047]      FIG. 9  is a flowchart to show an operation procedure of the converging device for mixing two liquids shown in  FIG. 8 ; 
           [0048]      FIG. 10  is a schematic representation of channels where two liquids are converged with each other; and 
           [0049]      FIGS. 11A to 11C  are drawings of a converging process for mixing two liquids using the channels in  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0050]    An embodiment of the invention will be discussed with reference to the accompanying drawings. 
       First Embodiment 
       [0051]      FIG. 1  is a top view of a microchannel chip for mixing two liquids according to an embodiment of the invention,  FIG. 2  is a sectional view taken on line II-II in  FIG. 1 , and FIG.  3  is a sectional view taken on line III-III in  FIG. 1 . 
         [0052]    A microchannel chip for mixing two liquids  10  according to the embodiment has a resin material  12  of a polymer, etc., deposited on a rectangular substrate  11  by injection molding, etc. At this time, the following port sections and channels are formed. 
         [0053]    The microchannel chip for mixing two liquids  10  in the example shown in the figure is provided with three port sections  13 ,  14 , and  15 . The first port section  13  is provided in the right end portion of the chip  10 , the second port section  14  is provided at the center to the top side of the chip  10 , and the third port section  15  is provided in the left end portion of the chip  10 . Each of the port sections  13 ,  14 , and  15  is a columnar hole having an opening in the top face of the chip  10  and a bottom reaching the substrate  11 . 
         [0054]    The first port section  13  and the third port section  15  are communicated with each other by a first channel  16  which is formed on the substrate  11  and is rectangular in cross section. A part of the first channel  16  to the third port section  15  is formed as a circle expanded on the top view (circular channel  17 ) and post-converged two liquids (described later) are accumulated in the circular channel  17 . The height of the circular channel  17  is the same as that of the first channel  16 . 
         [0055]    The second port section  14  and the first channel  16  are communicated with each other by a second channel  18  which is formed on the substrate  11 , is narrow and short, and is rectangular in cross section. The capillary force of the second channel  18  is formed larger than that of the first channel  16 . In the example shown in the figure, the equivalent radius of the rectangular shape in the cross section of the second channel  18  is formed smaller than the equivalent radius of the first channel  16 . Between the second port section  14  and the first channel  16  communicated by the second channel  19 , the capillary force of the second port section  14  is formed smaller than that of the first channel  16 . 
         [0056]    That is, the microchannel chip for mixing two liquids  10  of the embodiment is formed so that the magnitude relation among the capillary forces becomes as follows: 
         [0000]      [Second channel 18]&gt;[first channel 16]&gt;[second port section 14] 
         [0057]    The capillary force is represented by pressure P and P=(2·γ·cos θ)/r where γ is surface tension of liquid [mN/m], θ is contact angle between liquid and channel [deg], and r is equivalent radius of channel. 
         [0058]    The equivalent radius is a half value of the equivalent diameter and the equivalent diameter has the same meaning as the term used generally in the mechanical engineering field. Assuming an equivalent circular pipe for a channel which is any shape in cross section (piping), the diameter of the equivalent circular pipe is referred to as “equivalent diameter” and equivalent diameter deq is defined as deq=4K/L where K is the cross-sectional area of piping and L is the perimeter of piping. 
         [0059]    To control the capillary forces, the diameters of the channels, etc., are adjusted at a low cost at the manufacturing time of the chip; adjustment can also be made by performing hydrophilic or water-repellent control in such a manner that the inner faces of channels are subjected to plasma treatment when the chip is manufactured. 
         [0060]    Two-liquid mixing will be discussed below with  FIGS. 4A to 5C : First, a liquid sample A of a predetermined quantity is entered in the first port section  13  and a liquid sample B of a predetermined quantity is entered in the second port section  14 . For example, the liquid sample A of a predetermined quantity treated in the preceding step of two-liquid converging treatment performed in the microchannel chip for mixing two liquids  10  may be automatically supplied to the first port section  13  by a pouring device or the liquid sample A of a predetermined quantity may be manually poured into the first port section  13 . A similar description also applies to a liquid sample B. 
         [0061]    When the liquid sample B of a predetermined quantity is supplied to the second port section  14 , the liquid sample B proceeds into the second channel  18  by the capillary force and is checked on the opening end face of the second channel  18  on the side of the first channel  16  by a Laplace pressure valve. 
         [0062]    Next, when the third port section  15  is decompressed by a decompression unit connected to the third port section  15 , the liquid sample A in the first port section  13  is sucked into the first channel  16  and proceeds in the first channel  16  in the direction of the circular channel  17 , as shown in  FIG. 5A . 
         [0063]    When the liquid sample A proceeding in the first channel  16  arrives at the opening end face of the second channel  18  ( FIG. 5B ), the Laplace pressure valve is opened. 
         [0064]    After this, decompression application to the third port section  15  is continued, whereby the liquid sample B in the second port section  14  flows into the first channel  16  without performing any special operation because of the magnitude relation between the capillary force of the second port section  14  and that of the first channel  16  (second port section  14 &lt;first channel  16 ) and converges into the liquid sample A without involving any air bubble. 
         [0065]    Further, when decompression application to the third port section  15  is continued, the sample resulting from the liquid sample B converging into the liquid sample A proceeds to the circular channel  17  and is accumulated therein, as shown in  FIG. 5C . However, the liquid sample B remains in the second channel  18  because of the magnitude relation between the capillary force of the second channel  18  and that of the first channel  16  (first channel  16 &lt;second channel  18 ). 
         [0066]    Therefore, to use the microchannel chip for mixing two liquids  10  of the embodiment, the liquid sample A of the first predetermined quantity supplied to the first port section  13  and the liquid sample B of a second predetermined quantity resulting from subtracting the volume of the second channel  18  from the given quantity supplied to the second port section  14  are converged with each other. 
         [0067]    The converging liquids A and B flowing into the circular channel  17  are mixed uniformly in the later mixing step. 
         [0068]    The embodiment described above holds true only if the magnitude relation between the withstand pressure of the Laplace pressure valve of the liquid sample B and pressure for transporting the liquid sample A is |withstand pressure of Laplace pressure valve|&gt;|decompression transport pressure of liquid sample A|. If the relation does not hold true, the valve is opened before the liquids converge, and an air layer is formed between the two liquids and the liquids cannot converge. 
       Second Embodiment 
       [0069]      FIG. 6  is a configuration drawing to show an embodiment of a converging device for mixing two liquids of the invention. The converging device for mixing two liquids of the embodiment includes the microchannel chip for mixing two liquids  10  previously described with reference to  FIGS. 1 to 5C , a liquid arrival detection sensor  19 , and a liquid delivery device  20 . 
         [0070]    The liquid arrival detection sensor  19  is provided in the proximity of the opening end of the second channel  18  on the side of the first channel  16  and is a sensor for detecting that the liquid sample A proceeding in the first channel  16  arrives at the opening end of the second channel  18 ; for example, it is implemented as a reflection fiber sensor. 
         [0071]    The liquid delivery device  20  includes a connector  21  connected to the opening of the third port section  15 , a connector  22  connected to the opening of the second port section  14 , a decompression unit  23  connected to the third port section  15  through the connector  21 , and a solenoid valve  24  of three ports (also called SV 1  in the description with  FIGS. 6 and 7 ) intervened between the decompression unit  23  and the connector  22 . 
         [0072]    The SV 1  has OFF-position and ON-position valve plugs; the OFF-position valve plug connects the second port section  14  to the decompression unit  23  through the connector  22  and the ON-position valve plug releases the second port section  14  into the atmosphere through the connector  22  and closes the connection portion to the decompression unit  23 . 
         [0073]      FIG. 7  is a flowchart to show an operation procedure of the converging device for mixing two liquids shown in  FIG. 6 . First, the liquid sample A of a first predetermined quantity is set in the first port section  13  and the liquid sample B of a given quantity is set in the second port section  14  (step S 1 ). Accordingly, the liquid sample B proceeds into the second channel  18  and is stopped by the Laplace pressure valve (state in  FIGS. 4A and 4B ). 
         [0074]    Next, the sensor  19  and the connectors of the liquid delivery device  20  are attached to the microchannel chip for mixing two liquids  10  (step S 2 ). At this time, the solenoid valve SV 1  is previously set to ON. If the connectors are connected to the chip  10  with the solenoid valve SV 1  OFF, when an elastic member (O ring, etc.,) of each connector becomes deformed, it is feared that air between the connector and the liquid level of the liquid sample B may be compressed and the Laplace pressure valve may be opened by the compression pressure. Thus, SV 1  is previously set to ON. 
         [0075]    Next, the solenoid valve SV 1  is set to OFF and the decompression unit  23  is caused to start decompression (step S 3 ). Accordingly, the second port section  14  and the third port section  15  are communicated with each other and the same decompression pressure is applied to both the port sections  14  and  15  and the liquid sample A proceeds in the first channel  16  as shown in  FIG. 5A . 
         [0076]    Since the same decompression pressure is applied to both the port sections  14  and  15 , the front pressure (opening end pressure on the side of the first channel) and the rear pressure (application pressure of the second port section  14 ) of the Laplace pressure valve become the same and the fear of allowing the liquid sample B to leak from the Laplace pressure valve to the first channel  16  is eliminated. 
         [0077]    When the sensor  19  detects the liquid sample A arriving at the Laplace pressure valve (state in  FIG. 5B ) at the next step S 4 , the solenoid valve SV 1  is automatically set to ON at step S 5 . 
         [0078]    As the liquid sample A arrives at the Laplace pressure valve, the Laplace pressure valve is opened and at this time as the SV 1  is ON, the pressure of the second port section  14  is released into the atmosphere. Accordingly, preparations for starting convergence of the liquid sample A and the liquid sample B are complete. 
         [0079]    When decompression transport is further continued at step S 6 , the two liquids A and B converged without involving any air bubble flow into the circular channel  17  and the mixing is complete. 
       Third Embodiment 
       [0080]      FIG. 8  is a drawing of the configuration of a converging device for mixing two liquids according to another embodiment of the invention. The converging device for mixing two liquids of the embodiment includes the microchannel chip for mixing two liquids  10  previously described with reference to  FIG. 1 , the liquid arrival detection sensor  19  previously described with reference to  FIG. 6 , and a liquid delivery device  30 . 
         [0081]    The liquid delivery device  30  includes a connector  31  connected to the opening of the first port section  13 , a connector  32  connected to the opening of the third port section  15 , a compression and decompression unit  33 , and solenoid valves  34  (called SV 1  in the description with  FIG. 9 ),  35  (called SV 2  in the description with  FIG. 9 ), and  36  (called SV 3  in the description with  FIG. 9 ) of three ports for performing the operation described later. 
         [0082]      FIG. 9  is a flowchart to show an operation procedure of the converging device for mixing two liquids shown in  FIG. 8 . First, the sample A of any desired quantity is set in the first port section  13  and the sample B of any desired quantity is set in the second port section  14  (step S 11 ). 
         [0083]    The sample may be poured manually or may be poured automatically by a pouring device as in the embodiment described above. The sample B proceeds into the second channel  18  by the capillary force and is stopped the end face facing the first channel  16  by the Laplace pressure valve. 
         [0084]    Next, the sensor  19  and the connectors  31  and  32  are attached to the microchannel chip  10  where the samples A and B are set. At this time, the solenoid valves SV 1 , SV 2 , and SV 3  are set to ON (step S 12 ). 
         [0085]    The SV 1  is set to OFF at the next step S 13 . Accordingly, applied pressure from the compression and decompression unit  33  passes through the OFF-position valve plug of the SV 1  and the ON-position valve plug of the SV 2  and is applied from the connector  31  to the first port section  13 . Accordingly, the liquid sample A in the first port section  13  is sent out to the first channel  16 . At this time, the downstream side of the liquid sample A, namely, the Laplace pressure valve face of the sample B is under the atmospheric pressure and thus there is no fear of allowing the sample B to leak from the valve. 
         [0086]    When the sample A arrives at the Laplace pressure valve and the sensor  19  detects the sample A arriving at the Laplace pressure valve (step S 14 ), then the SV 1  is automatically set to ON (step S 15 ). Accordingly, applying the pressure to the first port section  13  is stopped. 
         [0087]    Next, all of the SV 1 , the SV 2 , and the SV 3  are automatically set to OFF and decompression force of the compression and decompression unit  33  is applied to the third port section  15  (step S 16 ). Accordingly, the sample A is transported under decompression through the first channel  16  to the circular channel  17 . At this time, the Laplace pressure valve is opened and thus the liquid sample B passed through the second channel  18  starts to converge into the liquid sample A. 
         [0088]    After this, without performing any special operation, as the transport under decompression is continued, the liquid sample B in the second port section  14  flows into the first channel  16  without involving any air bubble because of the magnitude relation between the capillary force of the second port section  14  and that of the first channel  16  (second port section  14 &lt;first channel  16 ) and the samples A and B converge. 
         [0089]    In the embodiments described above, only one pair of the second port section  14  and the second channel  18  is provided in the first channel and the two-liquid convergence has been described, but a plurality of pairs are provided and are apposed along the first channel  16 , whereby it is made possible to execute a plurality of two-liquid convergence in order for mixing three or more liquid samples with each other. 
         [0090]    In such a converging device for mixing three or more liquid samples with each other, for example, the valve  24  as shown in  FIG. 6  may be provided for each port section and the corresponding port section may be released into the atmospheric pressure each time the first liquid arrives at the Laplace pressure valve. 
         [0091]    According to the invention, liquid samples each having a fixed quantity can be well mixed with each other without involving any air bubble, so that the invention is useful for a converging device for mixing liquids and a microchannel chip for mixing liquids. 
         [0092]    The entire disclosure of each and every foreign patent application from which the benefit of foreign priority has been claimed in the present application is incorporated herein by reference, as if fully set forth.