Abstract:
Disclosed herein is a reactor plate which prevents the entry of foreign matter from the outside and the pollution of a surrounding environment. A reactor plate ( 1 ) includes a reaction well ( 5 ), a reaction well channel connected to the reaction well ( 5 ), and reaction well air vent channels ( 19 ) and ( 21 ) connected to the reaction well ( 5 ). The reaction well channel has a main channel ( 13 ), a metering channel ( 15 ) branched off the main channel ( 13 ), and an injection channel ( 17 ) of which one end is connected to the metering channel ( 15 ) and the other end is connected to the reaction well ( 5 ). The main channel ( 13 ) and the reaction well air vent channel ( 21 ) can be hermetically sealed. The injection channel ( 17 ) is formed narrower than the metering channel ( 15 ) not so as to allow the passage of a liquid at a liquid introduction pressure applied to introduce the liquid into the main channel ( 13 ) and the metering channel ( 15 ) and at a purge pressure applied to purge the liquid from the main channel ( 13 ) but so as to allow the passage of the liquid at a pressure higher than the liquid introduction pressure and the purge pressure.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a reactor plate suitable for use in various assays and analyses such as biological and biochemical assays and general chemical analyses in the fields of medical care and chemistry, and a reaction processing method for processing such a reactor plate. 
     Description of the Related Art 
     As small reactors for use in biochemical assays or general chemical analyses, micro multi-chamber devices are used. Examples of such devices include micro well reactor plates such as a microtiter plate constituted from a plate-shaped substrate having a plurality of wells formed in the surface thereof (see, for example, Japanese Patent Application Laid-open No. 2005-177749) and the like. 
     Further, as a structure for dispensing a small amount of liquid which can quantitatively treat a small amount of liquid, a structure having a first channel, a second channel, a third channel which is in communication with the first channel through an opening provided in the channel wall of the first channel, and a fourth channel which is in communication with the second channel through an opening provided in the channel wall of the second channel, connects one end of the third channel to the second channel, and has relatively lower capillary attraction than the third channel is developed (see, for example, Japanese Patent Application Laid-open Nos. 2004-163104 and 2005-114430). When such a structure for dispensing a small amount of liquid is used, a liquid introduced into the first channel is drawn into the third channel, and then the liquid remaining in the first channel is removed, and as a result, the liquid having a volume corresponding to the capacity of the third channel is dispensed into the second channel. 
     SUMMARY OF THE INVENTION 
     Meanwhile, when a conventional micro well reactor plate is used, the top surface of the reactor plate is open to the atmosphere. Therefore, there is a possibility that foreign matter will enter a sample from outside or, on the other hand, a reaction product will pollute a surrounding environment. 
     Further, in the structure for dispensing a small amount of liquid disclosed in Japanese Patent Application Laid-open Nos, 2004-163104 and 2005-114430, each of the first and second channels has a port for introducing a liquid at each end thereof. However, these ports are open to the atmosphere, and therefore there is a possibility that a reaction product will leak through the ports and then pollute a surrounding environment. 
     It is therefore an object of the present invention to provide a reactor plate which can prevent the entry of foreign matter from outside and the pollution of a surrounding environment, and a reaction processing method using such a reactor plate. 
     The present invention is directed to a reactor plate including a reaction well, a reaction well channel connected to the reaction well, and a reaction well air vent channel connected to the reaction well. The reaction well channel is constituted from a groove formed in the contact surface between two members bonded together or from the groove and a through hole formed in the member. The reaction well channel includes a main channel, a metering channel branched off the main channel and having a predetermined capacity, and an injection channel of which one end is connected to the metering channel and the other end is connected to the reaction well. The main channel and the reaction well air vent channel are hermetically sealed. The injection channel is formed narrower than the metering channel not so as to allow the passage of a liquid at a liquid introduction pressure applied to introduce the liquid into the main channel and the metering channel and at a purge pressure applied to purge the liquid from the main channel but so as to allow the passage of the liquid at a pressure higher than the liquid introduction pressure and the purge pressure. 
     The present invention is also directed to a reaction processing method using the reactor plate according to the present invention, the method including: filling the main channel and the metering channel with a liquid at the introduction pressure; purging the liquid from the main channel by flowing a gas through the main channel while allowing the liquid to remain in the metering channel; and injecting the liquid contained in the metering channel into the reaction well through the injection channel by creating a positive pressure higher than the introduction pressure in the main channel, or by creating a negative pressure in the reaction well, or by creating a positive pressure higher than the introduction pressure in the main channel and creating a negative pressure in the reaction well. 
     In a case where the injection channel is constituted from a plurality of channels, the phrase “the injection channel is formed narrower than the metering channel” means that each of the channels constituting the injection channel is formed narrower than the metering channel. 
     In the above-described channel configuration, since the main channel and the reaction well air vent channel are hermetically sealed, it is possible to prevent the entry of foreign matter from the outside of the reactor plate and the pollution of a surrounding environment with the liquid. 
     In the above-described channel configuration, the contact angle of the injection channel with a water droplet is, for example, 90° or larger, and the area of an interface between the injection channel and the metering channel is, for example, 1 to 10,000,000 μm 2  (square micrometers). It is noted that in a case where the injection channel is constituted from a plurality of channels, the phrase “the area of an interface between the injection channel and the metering channel” means the area of an interface between each of the channels constituting the injection channel and the metering channel. 
     The reactor plate according to the present invention may include the plurality of reaction wells. In this case, the metering channel and the injection channel may be provided for each of the reaction wells, and the plurality of metering channels may be connected to the main channel. 
     A projecting portion may be provided so as to project from a top inner surface of the reaction well. In this case, the other end of the injection channel is located at the tip of the projecting portion. The projecting portion includes one having a proximal end and a distal end narrower than the proximal end. 
     The reactor plate according to the present invention may further include a sealed well other than the reaction well. An example of the sealed well includes a sample well for containing a sample liquid. Further, the sample well may be hermetically sealed with an elastic member which allows a dispensing device having a sharp tip to pass through to form a through hole and which also allows the through hole to be closed by pulling out the dispensing device due to its elasticity. Furthermore, the sample well may previously contain a liquid for pretreating a sample or a reagent. 
     The reactor plate according to the present invention may further include one or more reagent wells, each of which is constituted from the sealed well, other than the sample well. The reagent well previously contains a reagent to be used for the reaction of a sample liquid and is sealed with a film, or has an openable and closable cap so that the reagent can be injected thereinto. An example of the film for sealing the reagent well to prevent the leakage of a reagent includes one through which a dispensing device having a sharp tip can pass. 
     In a case where the reactor plate according to the present invention is intended to be used for gene analysis, the reactor plate preferably includes a gene amplification well which is constituted from the sealed well and used for carrying out gene amplification reaction. The gene amplification well preferably has a shape suitable for controlling a temperature according to a predetermined temperature cycle. It is noted that gene amplification can also be carried out also in the reaction well. 
     The reactor plate according to the present invention may further include a sealed well channel connected to the sealed well, a syringe for sending a liquid, and a switching valve for connecting the syringe to the reaction well channel or the sealed well channel. 
     An example of the switching valve includes a rotary valve. The rotary valve may have a port to be connected to the syringe at the center of rotation. In this case, the syringe may be placed on the rotary valve. 
     The reaction well can be used for carrying out at least any one of color reaction, enzymatic reaction, fluorescence reaction, chemiluminescence reaction, and bioluminescence reaction. 
     In a case where the reactor plate according to the present invention is intended to be used for measuring a gene-containing sample, a sample previously subjected to gene amplification reaction may be introduced into the reactor plate, or a gene amplification reagent may be previously contained in the reaction well or the reactor plate may be designed to allow a gene amplification reagent to be dispensed into the reaction well so that gene amplification reaction can be carried out in the reaction well of the reactor plate. 
     Examples of the gene amplification reaction include PCR method and LAMP method. For example, as PCR method for amplifying DNA, a method is proposed for directly subjecting a sample such as blood to PCR reaction without pretreating the sample. More specifically, this method is a nucleic acid synthesis method for amplifying a target gene contained in a gene-containing sample by adding a gene-containing body contained in the gene-containing sample or the gene-containing sample itself to a gene amplification reaction liquid and then adjusting the pH of the thus obtained reaction mixture to 8.5 to 9.5 (25° C.) (see Japanese Patent No, 3452717). 
     The reaction well may be made of an optically-transparent material so that optical measurement can be carried out from the bottom of the reaction well or from above the reaction well. 
     In a case where a liquid to be introduced into the reaction well channel contains a gene, the reaction well may contain a probe which reacts with the gene. Further, the probe may be fluorescently-labeled. 
     Effect of the Invention 
     As described above, since the reaction processing method according to the present invention is carried out using the reactor plate according to the present invention including a reaction well, a reaction well channel connected to the reaction well, and a reaction well air vent channel connected to the reaction well, wherein the reaction well channel is constituted from a groove formed in the contact surface between two members bonded together or from the groove and a through hole formed in the member and includes a main channel, a metering channel branched off the main channel and having a predetermined capacity, and an injection channel whose one end is connected to the metering channel and the other end is connected to the reaction well, and wherein the main channel and the reaction well air vent channel are hermetically sealed and the injection channel is formed narrower than the metering channel and does not allow the passage of a liquid at an introduction pressure applied to introduce the liquid into the main channel and the metering channel and at a purge pressure applied to purge the liquid from the main channel but allows the passage of the liquid at a pressure higher than the introduction pressure and the purge pressure, it is possible to prevent the entry of foreign matter from the outside of the reactor plate and the pollution of a surrounding environment with the liquid. 
     Further, since the reactor plate according to the present invention has the reaction well air vent channel connected to the reaction well, it is possible to move a gas between the reaction well and the reaction well air vent channel when a liquid is injected into the reaction well through the injection channel, thereby making it possible to smoothly inject the liquid into the reaction well. The reaction well air vent channel can also be used to suck a gas contained in the reaction well to decompress the reaction well to inject a liquid into the reaction well. 
     In a case where the reactor plate according to the present invention is intended to be used for measuring a gene-containing sample, the sample injected into the reactor plate and then introduced into the reaction well can be processed in a closed system, and therefore it is possible to prevent the pollution of an environment outside the reactor plate and the pollution of the sample with foreign matter from outside the reactor plate. 
     In the channel configuration described above as an example of a channel configuration, the contact angle of each of the metering channel and the injection channel with a water droplet is preferably 90° or larger, and the area of an interface between the injection channel and the metering channel is preferably 1 to 10,000,000 μm 2 . This makes it difficult for a liquid to enter the injection channel when the liquid is introduced into the main channel and the metering channel, thereby making it possible to increase an introduction pressure applied to introduce the liquid into the main channel and the metering channel. 
     The reactor plate according to the present invention may include the plurality of reaction wells. In this case, by providing the metering channel and the injection channel for each of the reaction wells and connecting the plurality of metering channels to the main channel, it is possible to introduce a liquid into the plurality of metering channels one after another and then simultaneously inject the liquid into the plurality of reaction wells through the injection channels. 
     A projecting portion may be provided so as to project from a top inner surface of the reaction well. In this case, the other end of the injection channel is located at the tip of the projecting portion. By allowing the projecting portion to have a proximal end and a distal end narrower than the proximal end, a liquid to be injected into the reaction well through the injection channel can be easily dropped into the reaction well. 
     The reactor plate according to the present invention may further include a sealed well other than the reaction well. For example, by providing a sample well for containing a sample liquid as the sealed well, it is possible to eliminate the necessity to separately prepare a well for containing a sample. 
     Further, the sample well may be hermetically sealed with an elastic member which allows a dispensing device having a sharp tip to pass through to form a through hole and which also allows the through hole to be closed by pulling out the dispensing device due to its elasticity. This makes it possible to inject a sample liquid into the sample well sealed with the elastic member and then to prevent the sample liquid from leaking out of the sample well. 
     Further, the sample well may previously contain a liquid for pretreating a sample or a reagent. This makes it possible to eliminate the necessity to dispense a liquid for pretreating a sample or a reagent into the sample well. 
     The reactor plate according to the present invention may further include one or more reagent wells, each of which is constituted from the sealed well, other than the sample well. By allowing the reagent well to previously contain a reagent to be used for the reaction of a sample liquid and sealing it with a film, or by allowing the reagent well to have an openable and closable cap so that the reagent can be injected thereinto, it is possible to eliminate the necessity to separately prepare a well for containing the reagent. 
     The reactor plate according to the present invention may further include a gene amplification well which is constituted from the sealed well and used for carrying out gene amplification reaction. By providing such a gene amplification well, it is possible to amplify a target gene in the reactor plate by gene amplification reaction such as PCR method or LAMP method even when a sample liquid contains only a very small amount of the target gene, thereby increasing analytical precision. 
     The reactor plate according to the present invention may further include a sealed well channel connected to the sealed well, a syringe for sending a liquid, and a switching valve for connecting the syringe to the reaction well channel or the sealed well channel. In this case, a liquid contained in the sealed well can be injected into the main channel by using the syringe and the switching valve. 
     The switching valve may be a rotary valve. In this case, by providing a port to be connected to the syringe at the center of rotation of the rotary valve, it is possible to simplify a channel configuration. 
     Further, by providing a port to be connected to the syringe at the center of rotation of the rotary valve and placing the syringe on the rotary valve, it is possible to shorten or eliminate a channel between the port and the syringe, thereby simplifying the structure of the reactor plate. In addition, it is also possible to effectively utilize a region on the switching valve, thereby making it possible to make the planar size of the reactor plate smaller as compared to a case where the syringe is placed in a region other than the region on the switching valve. 
     In a case where the reactor plate according to the present invention is intended to be used for measuring a gene-containing sample, the reactor plate may be designed to allow gene amplification reaction to be carried out in the reaction well. This eliminates the necessity to prepare a sample which has been subjected to gene amplification reaction outside the reactor plate. 
     Further, the reaction well may be made of an optically-transparent material so that optical measurement can be carried out from the bottom of the reaction well or from above the reaction well. This makes it possible to optically measure a liquid contained in the reaction well without transferring the liquid into another well. 
     In a case where a liquid to be introduced into the reaction well channel contains a gene, the reaction well may contain a probe which reacts with the gene. This makes it possible to detect a gene having a base sequence corresponding to the probe in the reaction well. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic plan view of one embodiment of a reactor plate according to the present invention.  FIG. 1B  is a schematic sectional view taken along the A-A line in  FIG. 1A , which further includes the sectional views of a bellows, drain spaces, a metering channel, an injection channel, and a sample well air vent channel. 
         FIG. 2  shows an exploded sectional view of the reactor plate in the embodiment shown in  FIG. 1A  and a schematic exploded perspective view of a switching valve. 
         FIGS. 3A to 3C  are schematic plan view, schematic perspective view, and schematic sectional view of one reaction well of the reactor plate in the embodiment shown in  FIG. 1A  and its vicinity, respectively. 
         FIG. 4A  is an expanded plan view of a sample well of the reactor plate in the embodiment shown in  FIG. 1A .  FIG. 4B  is a sectional view taken along the B-B line in  FIG. 4A . 
         FIG. 5A  is an expanded plan view of a reagent well of the reactor plate in the embodiment shown in  FIG. 1A .  FIG. 5B  is a sectional view taken along the C-C line in  FIG. 5B . 
         FIG. 6A  is an expanded plan view of a well for air suction of the reactor plate in the embodiment shown in  FIG. 1A .  FIG. 6B  is a sectional view taken along the D-D line in  FIG. 6A . 
         FIG. 7  is a schematic sectional view showing the reactor plate and a reaction processing apparatus for processing the reactor plate. 
         FIG. 8  is a plan view for explaining the operation of introducing a sample liquid into reaction wells from a sample well. 
         FIG. 9  is a plan view for explaining operation following the operation explained with reference to  FIG. 8 . 
         FIG. 10  is a plan view for explaining operation following the operation explained with reference to  FIG. 9 . 
         FIG. 11  is a plan view for explaining operation following the operation explained with reference to  FIG. 10 . 
         FIG. 12  is a plan view for explaining operation following the operation explained with reference to  FIG. 11 . 
         FIG. 13  is a plan view for explaining operation following the operation explained with reference to  FIG. 12 . 
         FIG. 14  is a plan view for explaining operation following the operation explained with reference to  FIG. 13 . 
         FIG. 15  is an expanded sectional view schematically showing a reaction well of a reactor plate according to another embodiment of the present invention and its vicinity. 
         FIG. 16  is an expanded sectional view schematically showing a reaction well of a reactor plate according to another embodiment of the present invention and its vicinity. 
         FIG. 17  is an expanded sectional view schematically showing a reaction well of a reactor plate according to another embodiment of the present invention and its vicinity. 
     
    
    
     DESCRIPTION OF THE NUMERALS 
     
         
           1  reactor plate 
           3  well base 
           5  reaction well 
           11  channel base 
           13  main channel 
           15  metering channel 
           17  injection channel 
           19 ,  21  reaction well air vent channel 
           35  sample well 
           35   b ,  35   d ,  35   e  sample well air vent channel 
           37  reagent well 
           37   b ,  37   d ,  37   e  reagent well air vent channel 
           39  well for air suction 
           39   b ,  39   d ,  39   e  air vent channel for the well for air suction 
           51  syringe 
           63  switching valve 
           73  channel spacer 
           75  projecting portion 
           77  injection channel 
           79  reaction well air vent channel 
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1A  is a schematic plan view of one embodiment of a reactor plate according to the present invention, and  FIG. 1B  is a schematic sectional view taken along the A-A line in  FIG. 1A , which further includes the sectional views of a metering channel  15 , an injection channel  17 , reaction well air vent channels  19  and  21 , a liquid drain space  29 , an air drain space  31 , and a bellows  53 .  FIG. 2  shows an exploded sectional view of the reactor plate in the embodiment shown in  FIG. 1A  and a schematic exploded perspective view of a switching valve.  FIGS. 3A to 3C  are schematic plan view, schematic perspective view, and schematic sectional view of one reaction well of the reactor plate in the embodiment shown in  FIG. 1A  and its vicinity, respectively.  FIG. 4A  is an expanded plan view of a sample well, and  FIG. 4B  is a sectional view taken along the B-B line in  FIG. 4A .  FIG. 5A  is an expanded plan view of a reagent well, and  FIG. 5B  is a sectional view taken along the C-C line in  FIG. 5A .  FIG. 6A  is an expanded plan view of a well for air suction, and  FIG. 6B  is a sectional view taken along the D-D line in  FIG. 6A . With reference to these drawings, the reactor plate according to one embodiment of the present invention will be described. 
     A reactor plate  1  includes a plurality of reaction wells  5  each having an opening in one surface of a well base  3 . In the reactor plate  1  according to this embodiment of the present invention, the reaction wells  5  are arranged in an array of 6 rows and 6 columns in a staggered format. In each of the reaction wells  5 , a reagent  7  and a wax  9  are contained. 
     The material of the well base  3  including the reaction wells  5  is not particularly limited. However, in a case where the reactor plate  1  is intended to be disposable, the material of the well base  3  is preferably a cheaply-available material. Preferred examples of such a material include resin materials such as polypropylene and polycarbonate. In a case where the reactor plate  1  is intended to be used to detect a substance in the reaction well  5  by absorbance, fluorescence, chemiluminescence, or bioluminescence, the container base  3  is preferably made of an optically-transparent resin so that optical detection can be carried out from the bottom of the reaction well  5 . Particularly, in a case where the reactor plate  1  is intended to be used for fluorescence detection, the container base  3  is preferably made of a low self-fluorescent (i.e., fluorescence emitted from a material itself is weak) and optically-transparent resin, such as polycarbonate. The thickness of the well base  3  is in a range of 0.2 to 4.0 mm, preferably in a range of 1.0 to 2.0 mm. From the viewpoint of low self-fluorescence, the thickness of the well base  3  for fluorescence detection is preferably small. 
     Referring to  FIGS. 1 and 3 , a channel base  11  is provided on the well base  3  so as to cover a region where the reaction wells  5  are arranged. The channel base  11  is made of, for example, PDMS (polydimethylsiloxane) or silicone rubber. The thickness of the channel base  11  is, for example, from 1.0 to 5.0 mm. The channel base  11  has a groove in its surface which is in contact with the well base  3 . The groove and the surface of the well base  3  together form a main channel  13 , the metering channel  15 , the injection channel  17 , the reaction well air vent channels  19  and  21 , and drain space air vent channels  23  and  25 . The main channel  13 , the metering channel  15 , and the injection channel  17  constitute a reaction well channel. In the surface of the channel base  11  which is in contact with the well base  3 , a recess  27  is also provided so as to be located above each of the reaction wells  5 . It is noted that, in  FIG. 1A  and  FIGS. 3A and 3B , the channel base  11  is not shown, and only the groove and recess provided in the channel base  11  are shown. 
     The main channel  13  is constituted from one channel, and is therefore bent so as to run in the vicinity of all the reaction wells  5 . One end of the main channel  13  is connected to a channel  13   a  constituted from a through hole provided in the well base  3 . The channel  13   a  is connected to a port of a switching valve  63  (which will be described later). The other end of the main channel  13  is connected to the liquid drain space  29  provided in the well base  3 . The main channel  13  is constituted from a groove having a depth of, for example, 400 μm (micrometers) and a width of, for example, 500 μm. It is noted that a part of the main channel  13  having a predetermined length (e.g., 250 μm) and located downstream of a position, to which the metering channel  15  is connected, has a width smaller than that of the other part of the main channel  13 , and the width of such a part is, for example, 250 μm. 
     The metering channel  15  branches off the main channel  13 , and is provided for each of the reaction wells  5 . The end of the metering channel  15  on the opposite side from the main channel  13  is located in the vicinity of the reaction well  5 . The depth of a groove constituting the metering channel  15  is, for example, 400 μm. The metering channel  15  is designed to have a predetermined internal capacity of, for example, 2.5 μL (microliters). A part of the metering channel  15  connected to the main channel  13  has a width larger than that of the above-described narrow part of the main channel  13  (e.g., 500 μm). Therefore, at a position where the metering channel  15  branches off the main channel  13 , the resistance to the flow of a liquid coming from one end of the main channel  13  is larger in the main channel  13  than in the metering channel  15 . For this reason, the liquid coming from one end of the main channel  13  first flows into the metering channel  15  to fill the metering channel  15 , and then flows downstream through the narrow part of the main channel  13 . 
     The injection channel  17  is also provided for each of the reaction wells  5 . One end of the injection channel  17  is connected to the metering channel  15 , and the other end of the injection channel  17  is connected to the recess  27  located above the reaction well  5  so as to be led to the space above the reaction well  5 . The injection channel  17  is designed to have a size allowing the liquid-tightness of the reaction well  5  to be maintained in a state where there is no difference between the pressure in the reaction well  5  and the pressure in the injection channel  17 . According to the present embodiment, the injection channel  17  is constituted from a plurality of grooves, and each groove has a depth of, for example, 10 μm and a width of, for example, 20 μm, and the pitch between the adjacent grooves is, for example, 20 μm, and the thirteen grooves are provided in a region having a width of 500 μm. In this case, the area of an interface between the groove constituting the injection channel  17  and the metering channel  15 , that is, the cross-sectional area of the groove constituting the injection channel  17  is 200 μm 2 . The recess  27  has a depth of, for example, 400 μm, and has a circular planar shape smaller than that of the reaction well  5 . 
     The reaction well air vent channel  19  is provided for each of the reaction wells  5 . One end of the reaction well air vent channel  19  is connected to the recess  27 , which is located above the reaction well  5 , at a position different from the position, to which the injection channel  17  is connected, so as to be located above the reaction well  5 . The reaction well air vent channel  19  is designed to have a size allowing the liquid-tightness of the reaction well  5  to be maintained in a state where there is no difference between the pressure in the reaction well  5  and the pressure in the reaction well air vent channel  19 . The other end of the reaction well air vent channel  19  is connected to the reaction well air vent channel  21 . According to the present embodiment, the reaction well air vent channel  19  is constituted from a plurality of grooves, and each groove has a depth of, for example, 10 μm and a width of, for example, 20 μm, and the pitch between the adjacent grooves is, for example, 20 μm, and the thirteen grooves are provided in a region having a width of 500 μm. 
     The reactor plate according to the present embodiment has the plurality of reaction well air vent channels  21 . To each of the reaction well air vent channels  21 , the plurality of reaction well air vent channels  19  are connected. These reaction well air vent channels  21  are provided to connect the reaction well air vent channels  19  to the air drain space  31  provided in the well base  3 . Each of the reaction well air vent channels  21  is constituted from a groove having a depth of, for example, 400 μm and a width of, for example, 500 μm. 
     The drain space air vent channel  23  is provided to connect the liquid drain space  29  to a port of the switching valve  63  (which will be described later). One end of the drain space air vent channel  23  is located above the liquid drain space  29 . The other end of the drain space air vent channel  23  is connected to a channel  23   a  constituted from a through hole provided in the well base  3 . The channel  23   a  is connected to a port of the switching valve  63  (which will be described later). The drain space air vent channel  23  is constituted from a groove having a depth of, for example, 400 μm and a width of, for example, 500 μm. 
     The drain space air vent channel  25  is provided to connect the air drain space  31  to a port of the switching valve  63  (which will be described later). One end of the drain space air vent channel  25  is located above the air drain space  31 . The other end of the drain space air vent channel  25  is connected to a channel  25   a  constituted from a through hole provided in the well base  3 . The channel  25   a  is connected to a port of the switching valve  63  (which will be described later). The drain space air vent channel  25  is constituted from a groove having a depth of, for example, 400 μm and a width of, for example, 500 μm. 
     On the channel base  11 , a channel cover  33  (not shown in  FIG. 1A ) is provided. The channel cover  33  is provided to fix the channel base  11  to the well base  3 . The channel cover  33  has a through hole formed to be located above each of the reaction wells  5 . 
     Referring to  FIGS. 1 and 4 , in the well base  3 , a sample well  35 , a reagent well  37 , and a well  39  for air suction are provided at positions other than the positions of a region where the reaction wells  5  are arranged, and the drain spaces  29  and  31 . The sample well  35 , the reagent well  37 , and the well  39  for air suction constitute sealed wells of the reactor plate according to the present invention. 
     In the well base  3 , a sample channel  35   a  constituted from a through hole extending from the bottom of the sample well  35  to the back surface of the well base  3  and a sample well air vent channel  35   b  constituted from a through hole extending from the top surface to the back surface of the well base  3  are provided in the vicinity of the sample well  35 . On the well base  3 , a projecting portion  35   c  is provided so as to surround an opening of the sample well  35 . In the projecting portion  35   c , a sample well air vent channel  35   d  constituted from a through hole is provided so as to be located above the sample well air vent channel  35   b . In the surface of the projecting portion  35   c , a sample well air vent channel  35   e  which allows the sample well  35  to communicate with the sample well air vent channel  35   d  is provided. 
     The sample well air vent channel  35   e  is constituted from one or more narrow holes, and each narrow hole has a width of, for example, 5 to 200 μm and a depth of, for example, 5 to 200 μm. The sample well air vent channel  35   e  is provided to maintain the liquid-tightness of the sample well  35  in a state where there is no difference between the pressure in the sample well  35  and the pressure in the sample well air vent channel  35   d . On the projecting portion  35   c , a septum  41  as an elastic member to cover the sample well  35  and the air vent channel  35   d  is provided. The septum  41  is made of an elastic material such as silicone rubber or PDMS. Therefore, a dispensing device having a sharp tip can pass through the septum  41  to form a through hole, but the through hole can be closed by pulling the dispensing device out of the septum  41  due to its elasticity. On the septum  41 , a septum stopper  43  for fixing the septum  41  is provided. The septum stopper  43  has an opening located above the sample well  35 . According to the present embodiment, a reagent  45  is previously contained in the sample well  35 . 
     As shown in  FIG. 5 , in the well base  3 , a reagent channel  37   a  constituted from a through hole extending from the bottom of the reagent well  37  to the back surface of the well base  3  and a reagent well air vent channel  37   b  constituted from a through hole extending from the top surface to the back surface of the well base  3  are provided in the vicinity of the reagent well  37 . On the well base  3 , a projecting portion  37   c  is provided so as to surround an opening of the reagent well  37 . In the projecting portion  37   c , a reagent well air vent channel  37   d  constituted from a through hole is provided so as to be located above the reagent well air vent channel  37   b . In the surface of the projecting portion  37   c , a reagent well air vent channel  37   e  which allows the reagent well  37  to communicate with the reagent well air vent channel  37   d  is provided. 
     The reagent well air vent channel  37   e  is constituted from one or more narrow holes, and each narrow hole has a width of, for example, 5 to 200 μm and a depth of, for example, 5 to 200 μm. The reagent well air vent channel  37   e  is provided to maintain the liquid-tightness of the reagent well  37  in a state where there is no difference between the pressure in the reagent well  37  and the pressure in the reagent well air vent channel  37   d . On the projecting portion  37   c , a film  47  made of, for example, aluminum to cover the reagent well  37  and the air vent channel  37   d  is provided. In the reagent well  37 , dilution water  49  is contained. 
     As shown in  FIG. 6 , the well  39  for air suction has the same structure as the reagent well  37 . That is, in the well base  3 , a channel  39   a  for air suction constituted from a through hole extending from the bottom of the well  39  for air suction to the back surface of the well base  3  and an air vent channel  39   b  for the well for air suction constituted from a through hole extending from the top surface to the back surface of the well base  3  are provided in the vicinity of the well  39  for air suction. On the well base  3 , a projecting portion  39   c  having air vent channels  39   d  and  39   e  for the well for air suction is provided so as to surround an opening of the well  39  for air suction. On the projecting portion  39   c , a film  47  made of, for example, aluminum is provided. The well  39  for air suction contains neither a liquid nor a solid, but is filled with air. 
     Referring to  FIGS. 1 and 2 , in the surface of the well base  3 , a syringe  51  is provided at a position other than positions of a region where the reaction wells  5  are arranged, the drain spaces  29  and  31 , and the wells  35 ,  37 , and  39 . The syringe  51  is constituted from a cylinder  51   a  formed in the well base  3  and a plunger  51   b  placed in the cylinder  51   a . In the well base  3 , a syringe channel  51   c  constituted from a through hole extending from the bottom of the cylinder  51   a  to the back surface of the well base  3  is provided. 
     In the well base  3 , the bellows  53  is also provided at a position other than the positions of a region where the reaction wells  5  are arranged, the drain spaces  29  and  31 , the wells  35 ,  37  and  39 , and the syringe  51 . The bellows  53  expands and contracts, and therefore the internal capacity of the bellows  53  is passively variable. The bellows  53  is placed in, for example, a through hole  53   a  provided in the well base  3 . 
     Further, a well bottom  55  is attached to the back surface of the well base  3  at a position other than the position of a region where the reaction wells  5  are arranged. In the well bottom  55 , an air vent channel  53   b  is provided at a position allowing the air vent channel  53   b  to communicate with the bellows  53 . The bellows  53  is connected to the well bottom  55  so as to be in close contact with the surface of the well bottom  55 . The well bottom  55  is provided to guide the channels  13   a ,  23   a ,  25   a ,  35   a ,  35   b ,  37   a ,  37   b ,  39   a ,  39   b ,  51   c , and  53   b  to predetermined port positions. 
     On the surface of the reaction well bottom  55  located on the opposite side from the well base  3 , the rotary switching valve  63  is provided. The switching valve  63  is constituted from disk-shaped sealing plate  57 , rotor upper  59 , and rotor base  61 . The switching valve  63  is attached to the well bottom  55  by means of a lock  65 . 
     The sealing plate  57  has a through hole  57   a , a through groove  57   b , and a through hole  57   c . The through hole  57   a  is provided in the vicinity of the peripheral portion of the sealing plate  57 , and is connected to any one of the channels  13   a ,  35   a ,  37   a , and  39   a . The through groove  57   b  is provided inside the through hole  57   a  and on a circle concentric with the sealing plate  57 , and is connected to at least two of the channels  23   a ,  25   a ,  35   b ,  37   b ,  39   b , and  53   b . The through hole  57   c  is provided at the center of the sealing plate  57 , and is connected to the syringe channel  51   c.    
     The rotor upper  59  has a through hole  59   a , a groove  59   b , and a through hole  59   c . The through hole  59   a  is provided at a position corresponding to the through hole  57   a  provided in the sealing plate  57 . The groove  59   b  is provided in the surface of the rotor upper  59  so as to correspond to the through groove  57   b  provided in the sealing plate  57 . The through hole  59   c  is provided at the center of the rotor upper  59 . 
     The rotor base  61  has a groove  61   a . The groove  61   a  is provided in the surface of the rotor base  61  to connect the through hole  59   a  provided in the peripheral portion of the rotor upper  59  and the through hole  59   c  provided at the center of the rotor upper  59  to each other. 
     By rotating the switching valve  63 , the syringe channel  51   c  is connected to any one of the channels  13   a ,  35   a ,  37   a , and  39   a , and at the same time, the air vent channel  53   b  is also connected to at least any one of the channels  23   a ,  25   a ,  35   b ,  37   b , and  39   b.    
     The switching valve  63  shown in  FIG. 1A  is in its initial state where the syringe channel  51   c  is not connected to any one of the channels  13   a ,  35   a ,  37   a , and  39   a , and the air vent channel  53   b  is not connected to any one of the channels  23   a ,  25   a ,  35   b ,  37   b , and  39   b , either. 
     As described above, the injection channel  17  provided in the reactor plate  1  is designed so that the liquid-tightness of the reaction well  5  is maintained in a state where there is no difference between the pressure in the injection channel  17  and the pressure in the reaction well  5 . The reaction well air vent channel  19  is also designed so that the liquid-tightness of the reaction well  5  is maintained in a state where there is no difference between the pressure in the reaction well  5  and the pressure in the reaction well air vent channel  19 . The main channel  13  constituting the reaction well channel, the liquid drain space  29  connected to the main channel  13 , and the drain space air vent channel  23  can be hermetically sealed by switching of the switching valve  63 . The wells  35 ,  37 , and  39  are sealed with the septum  41  or the film  47 . The channels  35   a ,  35   b ,  37   a ,  37   b ,  39   a , and  39   b  connected to the wells  35 ,  37 , and  39 , respectively, can be hermetically sealed by switching the switching valve  63 . One end of the air vent channel  53   b  is connected to the bellows  53  and therefore the air vent channel  53   b  is hermetically sealed. As described above, the wells and channels in the reactor plate  1  constitute a closed system. It is noted that even in a case where the reactor plate  1  does not have the bellows  53  and the air vent channel  53   b  is connected to the atmosphere outside the reactor plate  1 , the air vent channel  53   b  can be cut off from the wells and the channels other than the air vent channel  53   b  provided in the reactor plate  1  by switching of the switching valve  63 , and therefore the wells for containing a liquid and the channels for flowing a liquid can be hermetically sealed. 
       FIG. 7  is a sectional view showing the reactor plate  1  shown in  FIG. 1  and a reaction processing apparatus for processing the reactor plate  1 . The reactor plate  1  shown in  FIG. 7  has the same structure as that shown in  FIG. 1 , and therefore the description thereof is omitted. 
     The reaction processing apparatus includes a temperature control system  67  for controlling the temperature of the reaction wells  5 , a syringe driving unit  69  for driving the syringe  51 , and a switching valve driving unit  71  for switching the switching valve  63 . 
       FIGS. 8 to 14  are plan views for explaining the operation of introducing a sample liquid into the reaction wells  5  from the sample well  35 . This operation will be described with reference to  FIGS. 1 and 8 to 14 . 
     A dispensing device having a sharp tip (not shown) is prepared, and the dispensing device is passed through the septum  41  provided on the sample well  35  to dispense, for example, 5 μL of a sample liquid into the sample well  35 . After the completion of the dispensing of the sample liquid, the dispensing device is pulled out of the septum  41 . By pulling the dispensing device out of the septum  41 , a through hole formed in the septum  41  is closed due to the elasticity of the septum  41 . 
     The syringe driving unit  69  is connected to the plunger  51   b  of the syringe  51 , and the switching valve driving unit  71  is connected to the switching valve  63 . 
     As shown in  FIG. 8 , the switching valve  63  in its initial state shown in  FIG. 1A  is rotated to connect the syringe channel  51   c  to the sample channel  35   a  and to connect the air vent channel  53   b  to the sample well air vent channel  35   b . At this time, the air vent channels  37   b  and  39   b  are also connected to the air vent channel  53   b . The sample well  35  contains, for example, 45 μL of a reagent  45 . 
     The syringe  51  is slidably moved to mix the sample liquid and the reagent  45  contained in the sample well  35 . Then, for example, only 10 μL of the mixture contained in the sample well  35  is sucked into the channel in the switching valve  63 , the syringe channel  51   c , and the syringe  51 . At this time, the bellows  53  expands and contracts with changes in the volume of a gas contained in the sample well  35 , since the sample well  35  is connected to the bellows  53  through the air vent channels  35   e ,  35   d , and  35   b , the switching valve  63 , and the air vent channel  53   b.    
     As shown in  FIG. 9 , the switching valve  63  is rotated to connect the syringe channel  51   c  to the reagent channel  37   a  and to connect the air vent channel  53   b  to the reagent well air vent channel  37   b . The reagent well  37  contains, for example, 190 μL of dilution water  49 . The mixture sucked into the channel in the switching valve  63 , the syringe channel  51   c , and the syringe  51  is injected into the reagent well  37 . Then, the syringe  51  is slidably moved to mix the mixture and the dilution water  49 . For example, the whole diluted mixture, that is, 200 μL of the diluted mixture is sucked into the channel in the switching valve  63 , the syringe channel  51   c , and the syringe  51 . At this time, the bellows  53  expands and contracts with changes in the volume of a gas contained in the reagent well  37 , since the reagent well  37  is connected to the bellows  53  through the air drain channels  37   e ,  37   d , and  37   b , the switching valve  63 , and the air vent channel  53   b.    
     As shown in  FIG. 10 , the switching valve  63  is rotated to connect the syringe channel  51   c  to the channel  13   a  connected to one end of the main channel  13  and to connect the air vent channel  53   b  to the channels  23   a  and  25   a  connected to the liquid drain space  29  and the air drain space  31 , respectively. The syringe  51  is driven in an extrusion direction to send the diluted mixture sucked into the channel in the switching valve  63 , the syringe channel  51   c , and the syringe  51  to the main channel  13 . As shown by the arrows and dots in  FIG. 10 , the diluted mixture injected into the main channel  13  through the channel  13   a  fills the metering channels  15  one after another in order of increasing distance from the channel  13   a , and then reaches the liquid drain space  29 . The injection channel  17  allows the passage of a gas but does not allow the passage of the diluted mixture at an introduction pressure applied to introduce the diluted mixture into the main channel  13  and the metering channels  15 . When the diluted mixture is introduced into the metering channel  15 , a gas contained in the metering channel  15  is transferred into the reaction well  5  through the injection channel  17 . Due to the transfer of the gas into the reaction well  5 , a gas contained in the reaction well  5  is partially transferred into the reaction well air vent channels  19  and  21 . Furthermore, a gas contained in the channels between the reaction well air vent channel  19  and the bellows  53  is sequentially moved toward the bellows  53  (see open arrows in  FIG. 10 ). Further, due to the injection of the diluted mixture into the liquid drain space  29 , a gas contained in the channels between the liquid drain space  29  and the bellows  53  is sequentially moved toward the bellows  53  (see open arrows in  FIG. 10 ). As a result, the bellows  53  expands. 
     As shown in  FIG. 11 , the switching valve  63  is rotated to connect the syringe channel  51   c  to the channel  39   a  for air suction and to connect the air vent channel  53   b  to the air vent channel  39   b  for the well for air suction. Then, the syringe  51  is driven in a suction direction to suck a gas contained in the well  39  for air suction into the channel in the switching valve  63 , the syringe channel  51   c , and the syringe  51 . At this time, the bellows  53  contracts due to the decompression of the well  39  for air suction (see open arrows in  FIG. 11 ), since the well  39  for air suction is connected to the bellows  53  through the air vent channels  39   e ,  39   d , and  39   b , the switching valve  63 , and the air vent channel  53   b.    
     As shown in  FIG. 12 , the switching valve  63  is rotated to connect the syringe channel  51   c  to the channel  13   a  and to connect the air vent channel  53   b  to the channels  23   a  and  25   a  as in the case of a connection state shown in  FIG. 10 . Then, the syringe  51  is driven in an extrusion direction to send a gas contained in the channel in the switching valve  63 , the syringe channel  51   c , and the syringe  51  into the main channel  13  to purge the diluted mixture from the main channel  13  (see open arrows in  FIG. 12 ). At this time, the diluted mixture remains in the metering channels  15  (see dots in  FIG. 12 ) because the injection channels  17  do not allow the passage of the diluted mixture at a purge pressure applied to purge the diluted mixture from the main channel  13 . The purged diluted mixture is injected into the liquid drain space  29 . Further, due to the injection of the diluted mixture into the liquid drain space  29 , a gas contained in the channels between the liquid drain space  29  and the bellows  53  is sequentially moved toward the bellows  53  (see open arrows in  FIG. 12 ). As a result, the bellows  53  expands. 
     As shown in  FIG. 13 , the switching valve  63  is rotated to connect the syringe channel  51   c  to the channel  39   a  for air suction and to connect the air vent channel  53   b  to the air vent channel  39   b  for the well for air suction as in the case of a connection state shown in  FIG. 11 . Then, the syringe  51  is driven in a suction direction to suck a gas contained in the well  39  for air suction into the channel in the switching valve  63 , the syringe channel  51   c , and the syringe  51 . At this time, as in the case described with reference to  FIG. 11 , the bellows  53  contracts (see open arrows in  FIG. 13 ). 
     As shown in  FIG. 14 , the switching valve  63  is rotated to connect the syringe channel  51   c  to the channel  13   a  and to connect the air vent channel  53   b  to the channel  25   a . It is noted that the connection state shown in  FIG. 14  is different from those shown in  FIGS. 10 and 12  in that the liquid drain space  29 , to which the downstream end of the main channel  13  is connected, is not connected to the channel in the switching valve  63 . Then, the syringe  51  is driven in an extrusion direction. Since the downstream end of the main channel  13  is not connected to the bellows  53 , a pressure larger than the liquid introduction pressure and the purge pressure is applied to the inside of the main channel  13 . As a result, the diluted mixture in the metering channels  15  is injected into the reaction wells  5  through the injection channels  17 . After the completion of the injection of the diluted mixture into the reaction wells  5 , a gas contained in the main channel  13  is partially flown into the reaction wells  5  through the metering channels  15  and the injection channels  17 . At this time, a gas contained in the channels between the reaction wells  5  and the bellows  53  is sequentially moved toward the bellows  53  (see open arrows in  FIG. 14 ), since the reaction wells  5  are connected to the bellows  53  through the reaction well air vent channels  19  and  21 , the air drain space  31 , the drain space air vent channel  25   a , and the air vent channel  53   b . As a result, the bellows  53  expands. 
     The switching valve  63  is returned to its initial state shown in  FIG. 1  to hermetically seal the wells, channels, and drain spaces provided in the reactor plate  1 . Then, the reaction wells  5  are heated by the temperature control system  67  to melt the wax  9 . As a result, the diluted mixture injected into each of the reaction wells  5  sinks below the wax  9 , and therefore the diluted mixture is mixed with the reagent  7  so that a reaction occurs. As described above, by using the reactor plate  1 , it is possible to perform reaction processing in a closed system. 
     Alternatively, the wax  9  may be melted before the injection of the diluted mixture into the reaction wells  5  by heating the reaction wells  5  by the temperature control system  67  so that the diluted mixture is injected into the reaction wells  5  containing the melted wax  9 . In this case, the diluted mixture injected into each of the reaction wells  5  immediately sinks below the wax  9 , and is then mixed with the reagent  7  so that a reaction occurs. Even when the switching valve  63  is in the connection state shown in  FIG. 14 , the hermeticity of the reactor plate  1  is maintained by the bellows  53 . By returning the switching valve  63  to its initial state shown in  FIG. 1  after the injection of the diluted mixture into the reaction wells  5 , it is possible to hermetically seal the wells, channels, and the drain spaces provided in the reactor plate  1 . It is noted that the switching valve  63  may be returned to its initial state shown in  FIG. 1  at any timing during the period from just after the injection of the diluted mixture into the reaction wells  5  until the end of the reaction between the diluted mixture and the reagent  7 , or may be returned to its initial state shown in  FIG. 1  after the completion of the reaction between the diluted mixture and the reagent  7 . As described above, by using the reactor plate  1 , it is possible to perform reaction processing in a closed system. In addition, it is also possible to maintain the hermeticity of the reactor plate  1  before and after reaction processing. 
     According to the present embodiment, grooves for forming the channels  13 ,  15 ,  17 ,  19 ,  21 , and  23  are provided in the channel base  11 , but the present invention is not limited to this embodiment. For example, grooves for forming all or part of these channels may be provided in the surface of the well base  3 . 
       FIG. 15  is an expanded sectional view schematically showing a reaction well of a reactor plate according to another embodiment of the present invention and its vicinity. The reactor plate according to another embodiment of the present invention has the same structure as the reactor plate described above with reference to  FIGS. 1 to 14  except that a channel spacer is provided between the well base and the channel base. 
     On the well base  3 , a channel spacer  73  is provided to cover a region where the reaction wells  5  are arranged. On the channel spacer  73 , the channel base  11  and the channel cover  33  are further provided in this order. The channel spacer  73  is made of, for example, PDMS or silicone rubber. The thickness of the channel spacer  73  is, for example, from 0.5 to 5.0 mm. The channel spacer  73  has a projecting portion  75  projecting into each of the reaction wells  5 . The projecting portion  75  is substantially trapezoidal in cross section. For example, the proximal end of the projecting portion  75  has a width of 1.0 to 2.8 mm, and the distal end of the projecting portion  75  has a width of 0.2 to 0.5 mm. That is, the distal end of the projecting portion  75  is narrower than the proximal end of the projecting portion  75 . Further, the projecting portion  75  has a super-water-repellent surface. In this regard, it is noted that it is not always necessary to subject the surface of the projecting portion  75  to water-repellent treatment. 
     Further, in the channel spacer  73 , an injection channel  77  is provided at a position corresponding to each of the projecting portions  75 . The injection channel  77  is constituted from a through hole extending from the distal end of the projecting portion  75  to the surface of the channel spacer  73  where the projecting portion  75  is not provided. The injection channel  77  has an inner diameter of, for example, 500 μm. The opening of the injection channel  77  provided on the channel base  11  side is connected to the injection channel  17  provided in the channel base  11 . It is noted that the reactor plate according to another embodiment of the present invention is different from the reactor plate described above with reference to  FIGS. 1 to 14  in that the channel base  11  does not have a recess  27 . The channel spacer  73  further has a reaction well air vent channel  79  constituted from a through hole. The reaction well air vent channel  79  is provided to allow the reaction well  5  to communicate with the reaction well air vent channel  19  provided in the channel base  11 . 
     Although not shown in  FIG. 15 , the channel spacer  73  has through holes at positions corresponding to both ends of the main channel  13 , one end of each of the reaction well air vent channels  21  located on the air drain space  31  side, and both ends of each of the drain space air vent channels  23  and  25  to connect these channels  13 ,  21 ,  23 , and  25  to the wells  29  and  31  provided in the well base  3  and the channels  23   a  and  25   a.    
     According to the embodiment of the present invention shown in  FIG. 15 , the end of the injection channel  77  on the opposite side from the injection channel  15  (i.e., the other end of the injection channel) is located at the tip of the projecting portion  75  which projects from the top inner surface of the reaction well  5 , and therefore a liquid is easily dropped into the reaction well  5  through the injection channels  15  and  77  when injected into the reaction well  5 . 
     Further, by placing the tip of the projecting portion  75  in the vicinity of the side wall of the reaction well  5  so that when a liquid passes through the injection channel  77  and is then discharged from the tip of the projecting portion  75 , a droplet of the liquid formed at the tip of the projecting portion  75  can come into contact with the side wall of the reaction well  5 , it is possible to inject the liquid into the reaction well  5  along the side wall of the reaction well  5 , thereby making it possible to more reliably inject the liquid into the reaction well  5 . However, the projecting portion  75  may be provided at a position which does not allow a droplet formed at the tip of the projecting portion  75  to be brought into contact with the side wall of the reaction well  5 . 
       FIG. 16  is an expanded sectional view schematically showing a reaction well of a reactor plate according to another embodiment of the present invention and its vicinity. 
     The reactor plate according to another embodiment of the present invention shown in  FIG. 16  is different from the reactor plate described above with reference to  FIG. 15  in that a projecting portion  81  is further provided in the reaction well  5 . The tip of the projecting portion  81  is located under the tip of the projecting portion  75 . By providing the projecting portion  81 , it becomes easy to guide a droplet formed at the tip of the projecting portion  75  into the reaction well  5 . The projecting portion  81  becomes particularly effective by subjecting the surface of at least the tip of the projecting portion  81  to hydrophilic treatment. 
       FIG. 17  is an expanded sectional view schematically showing a reaction well of a reactor plate according to yet another embodiment of the present invention and its vicinity. 
     The reactor plate according to yet another embodiment of the present invention shown in  FIG. 17  is different from the reactor plate described above with reference to  FIG. 16  in that a stepped portion  83  and a linear projecting portion  85  are further provided. The stepped portion  83  is provided in the side wall of the reaction well  5 , and the linear projecting portion  85  is provided on the top surface of the stepped portion  83  in such a manner that a space is left between the tip of the linear projecting portion  85  and the top surface of the reaction well  5 . The stepped portion  83  and the linear projecting portion  85  are circular when viewed from above. Further, the tip of the linear projecting portion  85  is provided in such a manner that a space is left between the tip of the linear projecting portion  85  and the side wall of the reaction well  5 . 
     By providing the linear projecting portion  85  in such a manner that a space is left between the tip of the linear projecting portion  85  and the top surface of the reaction well  5  and between the tip of the linear projecting portion  85  and the side wall of the reaction well  5 , it is possible to prevent a liquid contained in the reaction well  5  from reaching the top surface of the reaction well  5  through the side wall of the reaction well  5 . The linear projecting portion  85  becomes particularly effective by subjecting the surface of at least the tip of the linear projecting portion  85  to water-repellent treatment. 
     The stepped portion  83  and the linear projecting portion  85  shown in  FIG. 17  can also be applied to the reactor plate in the embodiment shown in  FIG. 15 . 
     In each of these various embodiments described above with reference to  FIGS. 15 to 17 , grooves for forming the channels  13 ,  15 ,  17 ,  19 ,  21 , and  23  are provided in the channel base  11 , but the present invention is not limited to these embodiments. For example, grooves for forming all or part of these channels may be provided in any one of the surfaces of the channel spacer  73  located on the channel base  11  side, the surface of the channel spacer  73  located on the well base  11  side, and the surface of the well base  3 . 
     Although the present invention has been described above with reference to the various embodiments, the present invention is not limited to these embodiments. The shape, material, position, number, and size of each component and the channel configuration of the reactor plate in the above description are merely examples, and various changes can be made without departing from the scope of the present invention defined in claims. 
     For example, the bellows  53  connected to the air vent channel  53   b  may have another structure as long as it is a variable capacity member whose internal capacity is passively variable. Examples of such a bellows  53  having another structure include a bag-shaped one made of a flexible material and a syringe-shaped one. 
     Further, the reactor plate according to the present invention does not always need to have a variable capacity member such as a bellows  53 . Further, in a case where a liquid such as a reagent is not previously contained in the well  35 ,  37 , or  39 , the air vent channel thereof does not always need to partially have the channel  35   e ,  37   e , or  39   e  constituted from a narrow hole. 
     Further, in each of the above embodiments, the air vent channels  35   b ,  37   b , and  39   b , which communicate with the wells  35 ,  37 , and  39  provided as sealed wells, are connected to the air vent channel  53   b  through the switching valve  63 , but may be directly connected to the outside of the reactor plate or a variable capacity part such as a bellows  53 . Further, each of the wells  35 ,  37 , and  39  may be sealed by using an openable and closable cap. 
     Further, in each of the above embodiments, the well base  3  is constituted from one component, but may be constituted from two or more components. 
     Further, the reagent contained in the reaction well  5  may be a dry reagent. It is noted that the sample well  35  and the reaction well  5  do not always need to previously contain a reagent. Further, in each of the above embodiments, the reagent well  37  contains dilution water  49 , but may contain a reagent instead of the dilution water  49 . 
     Further, the well base  3  may further have a gene amplification well for carrying out gene amplification reaction. For example, the empty reagent well  37  may be used as a gene amplification well. 
     Further, by previously placing a reagent for gene amplification reaction in the reaction well  5 , it is possible to carry out gene amplification reaction in the reaction well  5 . Further, in a case where a liquid to be introduced into the main channel  13  contains a gene, a probe which reacts with the gene may be previously placed in the reaction well  5 . 
     Further, in each of the above embodiments, the syringe  51  is placed on the switching valve  63 . However, the position of the syringe  51  is not limited to a position on the switching valve  63 , and the syringe  51  may be placed at any position. 
     Further, the reactor plate according to the present invention does not always need to have the syringe  51 , and a syringe provided outside the reactor plate may be used to discharge and suck a liquid or a gas. 
     Further, in each of the above embodiments, the rotary switching valve  63  is used as a switching valve. However, a switching valve for use in the reactor plate according to the present invention is not limited thereto, and various channel switching valves can be used. The reactor plate according to the present invention may have a plurality of switching valves. 
     Further, in each of the above embodiments, a liquid filling the metering channel  15  is injected into the reaction well  5  through the injection channel  17  by applying a pressure to the inside of the main channel  13  after air purge, but the reaction processing method according to the present invention is not limited to such a method. For example, a liquid filling the metering channel  15  may be injected into the reaction well  5  through the injection channel  17  by creating a negative pressure in the reaction well air vent channel  21  and then in the reaction well  5 . In this case, it is necessary to change the channel configuration of the reactor plate so that a negative pressure can be created in the reaction well air vent channel  21  by using the syringe  51 . Alternatively, another syringe may be additionally prepared. In this case, a positive pressure is created in the main channel  13  and a negative pressure is created in the reaction well  5  to inject the liquid into the reaction well  5 . 
     Further, in each of the above embodiments, one main channel  13  is provided, and all the metering channels  15  are connected to the main channel  13 . However, the channel configuration of the reactor plate according to the present invention is not limited thereto. For example, a plurality of main channels may be provided. In this case, one or more metering channels may be connected to each of the main channels. 
     In the reactor plate according to the present invention, the main channel can be hermetically sealed. In this regard, the main channel may be hermetically sealed by, for example, allowing both ends of the main channel to be openable and closable. The phrase “allowing both ends of the main channel to be openable and closable” includes a case where each end of the main channel is connected to another space, and the end of the space located on the opposite side from the main channel is openable and closable. In the case of each of the above embodiments, such another space corresponds to, for example, the channel  13   a , the liquid drain space  29 , the drain space air vent channel  23 , or the channel  23   a.    
     In the reactor plate according to the present invention, the reaction well air vent channel can be hermetically sealed. In this regard, the reaction well air vent channel may be hermetically sealed by, for example, allowing the end of the reaction well air vent channel located on the opposite side from the reaction well to be openable and closable. The phrase “allowing the end of the reaction well air vent channel located on the opposite side from the reaction well to be openable and closable” includes a case where the end of the reaction well air vent channel located on the opposite side from the reaction well is connected to another space, and the end of the space located on the opposite side from the reaction well air vent channel is openable and closable. In the case of each of the above embodiments, such another space corresponds to, for example, the air drain space  31 , the drain space air vent channel  25 , or the channel  25   a.    
     In the case of such an aspect, a liquid is introduced into the main channel and the metering channels, and then the liquid is purged from the main channel, and then the liquid remaining in the metering channels is injected into the reaction wells, and then both ends of the main channel and one end of the reaction well air vent channel located on the opposite side from the reaction well are closed to hermetically seal the main channel and the reaction well air vent channel. 
     The present invention can be applied to measurements of various chemical and biochemical reactions.