Abstract:
A fluid handling apparatus  10  has a plurality of fluid handling subassemblies  16  arrayed on a plate body  12 . Each of the fluid handling subassemblies includes: an injecting section  26  for injecting a fluid; a fluidized section  28  for allowing the fluid to continuously flow downwards; a fluid housing chamber  30  for receiving the fluid from the fluidized section; a wall portion  20  formed between the fluid housing chamber and the fluidized section; slits  20   b  for allowing the fluid to enter the fluid housing chamber; and a surface-area increasing means  22  for increasing the area of a contact surface with the fluid in the fluidized section. The slits extend from a lower end positioned in the vicinity of the lower end of the fluidized section, to an upper end higher than the upper end of the fluidized section, for allowing the injecting section and fluidized section to be communicated with the fluid housing chamber.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a fluid handling apparatus and a fluid handling unit for use therein. More specifically, the invention relates to a fluid handling apparatus capable of being used as a sample analyzing apparatus for analyzing samples, such as biosubstances representative of functional substances, and a fluid handling unit for use therein. 
     2. Description of the Prior Art 
     As conventional methods for specifically detecting biosubstances, such as proteins, there are known various methods for causing an antigen-antibody reaction using an antibody to a specific biosubstance, to carry out the visual recognition or spectroscopic measurement of a reactant thus obtained, to detect the biosubstance. 
     As methods for quantifying a reactant obtained by an antigen-antibody reaction of a biosubstance, such as a protein, there are widely adopted some methods, such as ELISA (Enzyme-Linked ImmunoSorbent Assay). In these methods, there is used a sample analyzing apparatus called a microplate wherein a large number of fine recessed portions generally called microwells (which will be hereinafter referred to as “wells”) are arrayed. The wall surfaces of the wells are coated with an antibody to a specific biosubstance, which is a target substance, as a capturing (or catching) material, to capture (or catch) the target substance by the capturing material to detect the target substance by measuring a reactant, which is obtained by an antigen-antibody reaction between the target substance and the antibody, by fluorescence, luminous reagents or the like. 
     In a typical method using a microplate, such as ELISA, a well is filled with a liquid, such as a specimen containing a target substance or an antibody reagent, as a reaction solution to cause a reaction. This reaction does not occur until the components in the liquid filled in the well are moved by molecular diffusion to reach the bottom and inner walls of the well. For that reason, if a microplate is allowed to stand, a theoretical reaction time depends on the diffusion time of the components in the liquid filled in the well. Since the molecules in the liquid move while colliding with the surrounding molecules, the speed of diffusion is very slow. If the target substance is a protein having a molecular weight of about 70,000, the speed of diffusion is about 0.5 to 1×10 −6  cm 2 /sec in a dilute aqueous solution (room temperature). Therefore, in the liquid filled in the well, the target substance located apart from the bottom and inner walls of the well is hardly allowed to react in a practical measuring time. In addition, since it is effective to cause the bottom and wall surfaces in the well serving as a reacting portion to uniformly contact the reaction solution in order to improve the efficiency of reaction in a microplate, it is required to use a larger quantity of liquid than the quantity of liquid required for the reaction. 
     Thus, in the conventional method using the microplate, such as ELISA, the antigen-antibody reaction proceeds only on the wall surface of the well coated with the capturing antibody. Therefore, the liquid must be allowed to stand until the reaction occurs after the target substance, antibody and substrate contained in the liquid fed into the well are suspended, circulated and sink to reach the wall surface of the well, so that there is a problem in that the efficiency of reaction is bad. In addition, in a microplate which is subdivided into a large number of wells, the quantity of liquid fed into each of the wells is limited, so that there is a problem in that the sensitivity of measurement is deteriorated. 
     In order to improve the sensitivity of measurement and shorten the measuring time in ELISA or the like, there is proposed a microplate capable of increasing the surface area of a reaction surface (capturing surface) to enhance the sensitivity of measurement by forming fine irregularities on the bottom face of each of wells serving as the reaction surface (see, e.g., Japanese Patent Laid-Open No. 9-159673). There is also proposed a microchip capable of increasing the surface area of a reaction surface to enhance the efficiency of reaction in a fine space by arranging a fine solid particle (bead) as a reaction solid phase in a microchannel of the microchip (see, e.g., Japanese Patent Laid-Open No. 2001-4628). Moreover, there is proposed a microplate capable of increasing the surface area of a reaction surface and saving the quantity of samples by forming a small-diameter recessed portion in the central portion of the bottom of each of wells. (see, e.g., Japanese Patent Laid-Open No. 9-101302). 
     However, in the microplate proposed in Japanese Patent Laid-Open No. 9-159673, there is a problem in that it is not possible to improve the efficiency of reaction although it is possible to improve the sensitivity of measurement. In addition, the microchip proposed in Japanese Patent Laid-Open No. 2001-4628 is not suitable for the measurement of a large number of specimens although it is possible to improve the efficiency of reaction, since it is a microchip having a microchannel structure, not a microplate typically used in ELISA or the like. Moreover, in the microplate proposed in Japanese Patent Laid-Open No. 9-101302, it is not possible to sufficiently improve the efficiency of reaction and the sensitivity of measurement, although it is possible to increase the surface area of the reaction surface to some extent to improve the efficiency of reaction and the sensitivity of measurement. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to eliminate the aforementioned problems and to provide a fluid handling apparatus which is capable of improving the efficiency of reaction and the sensitivity of measurement with a simple structure and of shortening a reaction time and a measuring time, when the apparatus is used as a sample analyzing apparatus for measuring a large number of specimens, and a fluid handling unit for use therein. It is another object of the present invention to allow the interior of the above described fluid handling apparatus or fluid handling unit for use therein to be efficiently washed to further improve the accuracy of analysis. 
     In order to accomplish the aforementioned and other objects, according to one aspect of the present invention, a fluid handling apparatus comprises an apparatus body and a plurality of fluid handling subassemblies arranged on the apparatus body, each of the fluid handling subassemblies comprising: an injecting section for injecting a fluid; a fluidized section for receiving the fluid from the injecting section to allow the fluid to continuously flow downwards; a fluid housing chamber for receiving the fluid from the fluidized section; a wall portion formed between the fluid housing chamber and the injecting section and between the fluid housing chamber and the fluidized section; an opening, formed in the wall portion, for allowing the fluid to enter the fluid housing chamber; and a surface-area increasing means, arranged in the fluidized section, for increasing an area of a contact surface with the fluid in the fluidized section, wherein the opening extends from a lower end, which is positioned in the vicinity of the lower end of the fluidized section, to an upper end, which is higher than the upper end of the fluidized section, for allowing the injecting section and the fluidized section to be communicated with the fluid housing chamber. 
     In this fluid handling apparatus, the opening is preferably a slit which passes through the wall portion, and the slit may have an upper portion having a width which is wider than that of a lower portion of the slit. The opening preferably has a lower end arranged at a level which is substantially equal to a bottom face of the fluid housing chamber. The apparatus body preferably comprises a frame and a plurality of supporting members which are arranged on the frame so as to be substantially parallel to each other, each of the supporting members having a plurality of recessed portions which are arranged at regular intervals in a row, and each of the plurality of fluid handling subassemblies being mounted in a corresponding one of the recessed portions. 
     In the above described fluid handling apparatus, the fluidized section is preferably arranged so as to surround the fluid housing chamber. Each of the plurality of recessed portions may comprise an upper recessed portion, and a lower recessed portion which is formed in a bottom face of the upper recessed portion, the fluidized section being formed between a partition wall member, which is inserted into each of the plurality of recessed portions, and the upper recessed portion, and the fluid housing chamber being surrounded by the partition wall member. In this case, an extended recessed portion for extending the upper cylindrical recessed portion in substantially horizontal directions is preferably formed in each of the plurality of recessed portions. The surface-area increasing means preferably comprises a large number of fine particles filled in the fluidized section, and may be a porous material. Moreover, a liquid injected into the injecting section preferably flows in the fluidized section and the opening due to capillarity. 
     According to another aspect of the present invention, a fluid handling unit comprises a supporting member and a plurality of fluid handling subassemblies which are arranged on the supporting member at regular intervals in a row, each of the fluid handling subassemblies comprising: an injecting section for injecting a fluid; a fluidized section for receiving the fluid from the injecting section to allow the fluid to continuously flow downwards; a fluid housing chamber, formed so as to be surrounded by the fluidized section, for receiving the fluid from the fluidized section; a wall portion formed between the fluid housing chamber and the injecting section and between the fluid housing chamber and the fluidized section; an opening, formed in the wall portion, for allowing the fluid to enter the fluid housing chamber; and a surface-area increasing means, arranged in the fluidized section, for increasing an area of a contact surface with the fluid in the fluidized section, wherein the opening extends from a lower end, which is positioned in the vicinity of the lower end of the fluidized section, to an upper end, which is higher than the upper end of the fluidized section, for allowing the injecting section and the fluidized section to be communicated with the fluid housing chamber. 
     In this fluid handling unit, the opening is preferably a slit which passes through the wall portion, and the slit may have an upper portion having a width which is wider than that of a lower portion of the slit. The opening preferably has a lower end arranged at a level which is substantially equal to a bottom face of the fluid housing chamber. The surface-area increasing means preferably comprises a large number of fine particles filled in the fluidized section, and may be a porous material. Moreover, a liquid injected into the injecting section preferably flows in the fluidized section and the opening due to capillarity. 
     Furthermore, throughout the specification, the term “opening” means a portion, a part of which passes through a wall portion, and includes an elongated through hole, such as a slit, which passes through a wall portion, as well as an elongated groove (recessed portion) having a through hole in a part thereof. 
     According to the present invention, it is possible to provide a fluid handling apparatus which is capable of improving the efficiency of reaction and the sensitivity of measurement with a simple structure and of shortening a reaction time and a measuring time, when the apparatus is used as a sample analyzing apparatus for measuring a large number of specimens, and a fluid handling unit for use therein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood more fully from the detailed description given herebelow and from the accompanying drawings of the preferred embodiments of the invention. However, the drawings are not intended to imply limitation of the invention to a specific embodiment, but are for explanation and understanding only. 
       In the drawings: 
         FIG. 1  is a perspective view of the first preferred embodiment of a fluid handling apparatus according to the present invention; 
         FIG. 2  is a perspective view showing a frame and a fluid handling subassemblies supporting member of the apparatus body of the fluid handling apparatus of  FIG. 1 ; 
         FIG. 3  is an enlarged plan view of the fluid handling subassemblies supporting member of  FIG. 2 ; 
         FIG. 4  is a sectional view taken along line IV-IV of  FIG. 3 ; 
         FIG. 5  is a perspective view showing a state that fluid handling subassemblies are mounted on the fluid handling subassemblies supporting member of  FIG. 2 ; 
         FIG. 6  is an enlarged plan view of one of the fluid handling subassemblies of the fluid handling apparatus of  FIG. 1 ; 
         FIG. 7  is a sectional view taken along line VII-VII of  FIG. 6 ; 
         FIG. 8  is a plan view showing a state that a lid member is removed from the fluid handling apparatus of  FIG. 6 ; 
         FIG. 9  is a sectional view taken along line IX-IX of  FIG. 8 ; 
         FIG. 10  is an exploded perspective view showing one of the fluid handling subassemblies of the fluid handing apparatus of  FIG. 1 , except for beads; 
         FIG. 11  is a sectional view of a cylindrical member of one of the fluid handling subassemblies of the fluid handling apparatus of  FIG. 1 ; 
         FIG. 12  is a side view of the cylindrical member of  FIG. 11 ; 
         FIG. 13  is a sectional view taken along line XIII-XIII of  FIG. 12 ; 
         FIG. 14  is a sectional view showing a modified example of the cylindrical member of  FIG. 11 ; 
         FIG. 15  is a plan view of one of fluid handling subassemblies of the second preferred embodiment of a fluid handling apparatus according to the present invention; 
         FIG. 16  is a sectional view taken along line XVI-XVI of  FIG. 15 ; 
         FIG. 17  is a sectional view of a cylindrical member of one of the fluid handling subassemblies of the fluid handling apparatus of  FIG. 15 ; 
         FIG. 18  is a side view of the cylindrical member of  FIG. 17 ; 
         FIG. 19  is a sectional view taken along line XIX-XIX of  FIG. 18 ; 
         FIG. 20  is a sectional view showing a modified example of the cylindrical member of  FIG. 17 ; 
         FIGS. 21A through 21I  are illustrations for explaining the flow of a liquid sample when the liquid sample is injected into one of the fluid handling subassemblies of the fluid handling apparatus of  FIG. 1 ; 
         FIGS. 22A through 22F  are illustrations for explaining the flow of a washing solution and the remaining liquid sample when the washing solution is injected for washing the interior of one of the fluid handling subassemblies of the fluid handling apparatus after the liquid sample is injected into and discharged from the one of the fluid handling subassemblies as shown in  FIGS. 21A through 21I ; 
         FIGS. 23A through 23F  are illustrations for explaining the flow of the washing solution and the remaining liquid sample when the washing solution is sucked from the one of the fluid handling subassemblies of the fluid handling apparatus after the washing solution is injected into the one of the fluid handling subassemblies of the fluid handling apparatus as shown in  FIGS. 22A through 22F ; 
         FIG. 24  is a sectional view showing one of fluid handling subassemblies of the third preferred embodiment of a fluid handling apparatus according to the present invention, which corresponds to  FIG. 9  showing the state that the lid member is removed from the one of the fluid handling subassemblies in the first preferred embodiment; 
         FIG. 25  is a graph showing the results of measurements of blank values in the measurements of absorbance using the fluid handling subassemblies in the first and third preferred embodiments; 
         FIG. 26  is a sectional view showing one of fluid handling subassemblies of the fourth preferred embodiment of a fluid handling apparatus according to the present invention, which corresponds to  FIG. 7  showing the one of the fluid handling subassemblies in the first preferred embodiment; and 
         FIG. 27  is a graph showing the results of measurements of blank values in the measurements of absorbance using the fluid handling subassemblies in the first and fourth preferred embodiments. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the accompanying drawings, the preferred embodiments of a fluid handling apparatus and a fluid handling unit for use therein according to the present invention will be described below in detail. 
       FIGS. 1 through 14  show the first preferred embodiment of a fluid handling apparatus according to the present invention. For example, the fluid handling apparatus  10  in this preferred embodiment can be used as an apparatus for analyzing a sample containing a biosubstance, such as a protein, which is representative of functional substances. In general, the fluid handling apparatus  10  can be used as a sample analyzing apparatus called a microwell plate for carrying out the measurement of a large number of specimens. As shown in  FIG. 1 , the fluid handling apparatus  10  comprises: an apparatus body  12 ; and a plurality of fluid handling subassemblies  16  (96(=8×12) fluid handling subassemblies in this preferred embodiment) mounted on the apparatus body  12 . 
     As shown in  FIGS. 1 and 2 , the apparatus body  12  is made of a resin material, such as polystyrene (PS), polycarbonate (PC) or polymethyl methacrylate (PMMA), or a glass material, and comprises: a substantially rectangular frame  11  which has a substantially rectangular through hole  11   a  in the center thereof and which has a thickness of a few millimeters, the length of each side of the frame  11  being in the range of from a few centimeters to over ten centimeters; and a plurality of fluid handling subassemblies supporting members  13  (12 fluid handling subassemblies supporting members in this preferred embodiment) mounted on the frame  11 . Furthermore, the through hole  11   a  of the frame  11  may be replaced with a recessed portion with bottom. Alternatively, the frame  11  may be a standard frame, such as a frame for microplate of SBS (Society for Biomolecular Screening) standard. The fluid handling subassemblies supporting members  13  may be made of a transparent material. However, if the fluid handling apparatus  10  in this preferred embodiment is used for measuring fluorescence, the fluid handling subassemblies supporting members  13  is preferably made of a member (e.g., a black member) which is difficult to allow light to pass through the member in order to suppress the rise of background during the measurement of fluorescence. 
     As shown in  FIG. 2 , each of the fluid handling subassemblies supporting members  13  comprises: an elongated supporting member body  13   a  having a shape of substantially rectangular parallelepiped, the length of which is substantially equal to the width of the through hole  11   a  of the frame  11 ; and a pair of substantially rectangular protruding portions  13   b  which protrude from the upper portions of the supporting member body  13   a  at both ends in longitudinal directions to extend along the upper surface of the supporting member body  13   a . As shown in  FIG. 1 , the supporting member bodies  13   a  of the fluid handling subassemblies supporting members  13  are inserted into the through hole  11   a  of the frame  11  to be mounted on the frame  11  substantially in parallel and adjacent to each other so that the protruding portions  13   b  are supported on a pair of upper surfaces  11   b  of the frame  11  extending in longitudinal directions. Thus, the apparatus body  12  is assembled. 
     As shown in  FIGS. 3 and 4 , a plurality of recessed portions  14  (eighth recessed portions  14  in this preferred embodiment) (which will be hereinafter referred to as “mounting recessed portions  14 ”) are formed in the upper surface of the supporting member body  13   a  of each of the fluid handling subassemblies supporting members  13  so as to be arranged at regular intervals in a row. In each of the mounting recessed portions  14 , one of the fluid handling subassemblies  16  is mounted as shown in  FIG. 5 . As shown in  FIGS. 3 and 4 , each of the mounting recessed portions  14  comprises: a substantially cylindrical large-diameter recessed portion  14   a  formed in the upper surface of the supporting member body  13   a ; an extended recessed portion  14   c  which is adjacent to the large-diameter recessed portion  14   a  to be formed in the upper surface of the supporting member body  13  so as to extend the upper portion of the large-diameter recessed portion  14   a  substantially in horizontal directions and which has a half depth of the large-diameter recessed portion  14   a ; and a substantially cylindrical small-diameter recessed portion  14   b  which is formed in a substantially central portion of the bottom face of the large-diameter recessed portion  14   a . Two facing surfaces of the extended recessed portion  14   c  extending from the large-diameter recessed portion  14   a  extend along the side face of the supporting member body  13   a  of the fluid handling subassemblies supporting member  13  extending in longitudinal directions (see  FIGS. 6 and 8 ). The bottom face of the extended recessed portion  14   c  is curved and inclined downwards as a distance from the large-diameter recessed portion  14   a  is decreased, and the bottom face of the large-diameter recessed portion  14   a  is inclined downwards as a distance from the small-diameter recessed portion  14   b  is decreased (see  FIGS. 7 and 9 ). The bottom face of the small-diameter recessed portion  14   b  has a fine recessed portion  14   d , which has a fine depth and a diameter substantially equal to the inside diameter of a cylindrical member  20  which will be described later, so as to form a gap for preventing the occurrence of interference fringe between the bottom face of the cylindrical member  20  and the bottom face of the mounting recessed portion  14  when the cylindrical member  20  is fitted into the small-diameter recessed portion  14   b.    
       FIGS. 6 through 10  are enlarged views showing one of the fluid handling subassemblies  16 , each of which is mounted in a corresponding one of the mounting recessed portions  14  of the fluid handling apparatus  10  in this preferred embodiment.  FIG. 6  is a plan view of one of the fluid handling subassemblies  16 , each of which is mounted in a corresponding one of the mounting recessed portions  14  of the fluid handling apparatus  10 , and  FIG. 7  is a sectional view taken along line VII-VII of  FIG. 6 .  FIG. 8  is a plan view showing a state that a lid member  25  is removed from one of the fluid handling subassemblies  16  of  FIG. 6 , and  FIG. 9  is a sectional view taken along line IX-IX of  FIG. 8 .  FIG. 10  is an exploded perspective view of one of the fluid handling subassemblies  16  (except for beads  22 ).  FIG. 11  is a sectional view of a cylindrical member  20  of the fluid handling subassembly  16  of  FIG. 7 , and  FIG. 12  is a side view of the cylindrical member  20  of  FIG. 11 .  FIG. 13  is a sectional view taken along line XIII-XIII of  FIG. 12 , and  FIG. 14  is a sectional view showing a modified example of the cylindrical member  20  of  FIG. 11 . 
     As shown in  FIGS. 6 through 10 , each of the fluid handling subassemblies  16  comprises: a cylindrical member  20  having a substantially cylindrical shape which has a diameter and height of a few millimeters; a large number of substantially spherical fine beads  22 ; a substantially annular disk-shaped partition plate  24 ; and a lid member  25 . 
     As shown in  FIGS. 7 and 9 , the cylindrical member  20  has a length which is substantially equal to the depth of the mounting recessed portion  14  (the depth of the large-diameter recessed portion  14   a  and small-diameter recessed portion  14   b ), and an outside diameter which is substantially equal to the inside diameter of the small-diameter recessed portion  14   b  of the mounting recessed portion  14 . The bottom portion of the cylindrical member  20  is designed to be fitted into the small-diameter recessed portion  14   b  of the mounting recessed portion  14 . Furthermore, since the extended recessed portion  14   c  is formed in this preferred embodiment, even if the inside diameter of the small-diameter recessed portion  14   b  and the outside diameter of the cylindrical member  20  are increased to decrease a gap between the cylindrical member  20  and the large-diameter recessed portion  14   a , it is possible to ensure a sufficiently large inlet of an injecting section  26  which will be described later. For example, the inside diameter of the cylindrical member  20  may be about 4.5 mm. The cylindrical member  20  has a bottom portion  20   a . As shown in  FIGS. 11 and 12 , the outer periphery of the cylindrical member  20  has one or a plurality of slits  20   b  (twelve slits  20   b  in this preferred embodiment) which allow liquid to pass therethrough and which inhibit the beads  22  from passing therethrough. The slits  20   b  pass through the cylindrical member  20  so as to extend from the upper face of the bottom portion  20   a  in longitudinal directions in parallel. The length of each of the slits  20   b  is greater than half of the length of the cylindrical member  20 , and the upper end of each of the slits  20   b  is arranged above the partition plate  24  when the fluid handling subassembly  16  is mounted in the mounting recessed portion  14 . Furthermore, the slits  20   b  are radially formed in the outer periphery of the cylindrical member  20  as shown in  FIG. 13  in this preferred embodiment. However, the slits  20   b  may be formed so as to pass through the outer periphery of the cylindrical member  20  while extending in four directions as shown in  FIG. 14  in order to facilitate the molding of the cylindrical member  20 . 
     The central portion of the partition plate  24  has a substantially circular opening into which the cylindrical member  20  is fitted. The peripheral portion of the partition plate  24  has a plurality of cut-out portions  24   a  (three cut-out portions  24   a  in this preferred embodiment) which extend in circumferential directions at regular intervals. The outside diameter of the partition plate  24  is substantially equal to the inside diameter of the large-diameter recessed portion  14   a  of the mounting recessed portion  14 , so that the partition plate  24  is fitted into the large-diameter recessed portion  14   a  of the mounting recessed portion  14  when it is inserted into the mounting recessed portion  14 . 
     The lid member  25  comprises: a cylindrical fitted portion which has an inside diameter substantially equal to the outside diameter of the cylindrical member  20  and which can be fitted into the opening of the upper end portion of the cylindrical member  20 ; and a flange portion which extends outwards in radial directions from a part of the upper end portion of the fitted portion. The flange portion extends so as to close the upper end portion of a space between the large-diameter recessed portion  14   a  of the mounting recessed portion  14  and the cylindrical member  20 , except for a portion on the side of the extended recessed portion  14   c  of the mounting recessed portion  14 . 
     In order to assemble the fluid handling subassembly  16  with this construction, the lower portion of the cylindrical member  20  is first fitted into the small-diameter recessed portion  14   b  of the mounting recessed portion  14  to be fixed thereto with an adhesive or the like. Then, a large number of beads  22  are filled in an annular space between the large-diameter recessed portion  14   a  of the mounting recessed portion  14  and the cylindrical member  20 . Then, the cylindrical member  20  is fitted into the opening of the partition plate  24  which is arranged on the beads  22  to be fixed thereto with an adhesive or the like. Thereafter, the lid member  25  is fitted into the opening of the upper end portion of the cylindrical member  20 . 
     If the fluid handling subassembly  16  is thus mounted in the mounting recessed portion  14 , a space serving as an injecting section  26  for injecting a fluid, such as a liquid sample, is formed between the cylindrical member  20  and the large-diameter recessed portion  14   a  and extended recessed portion  14   c  of the mounting recessed portion  14  over the partition plate  24 . A portion of the upper end portion of the injecting section  26 , which is not closed by the lid member  25  and which is arranged on the side of the extended recessed portion  14   c , serves as an inlet. Below the injecting section  26 , a fluidized section  28 , which is a substantially annular space capable of being used as a reaction section filled with the large number of beads  22 , is formed between the large-diameter recessed portion  14   a  of the mounting recessed portion  14  and the cylindrical member  20 . The fluidized section  28  is communicated with the injecting section  26  via the cut-out portions  24   a  of the partition plate  24  serving as fluidized section inlets. In the cylindrical member  20 , there is formed a fluid housing chamber  30  which is a substantially cylindrical space capable of being used as a measuring section. The fluid housing chamber  30  thus formed is communicated with the injecting section  26  and fluidized section  28  via the slits  20   b.    
     Thus, in the fluid handling subassembly  16  in this preferred embodiment, the interior of the mounting recessed portion  14  having a size, which is equal to that of each of wells of a microplate, is divided into the fluidized section  28 , which can be used as a reaction section, and the fluid housing chamber  30 , which can be used as a measuring section, by the cylindrical member  20  extending in substantially vertical directions. Thus, even if the quantity of a liquid, such as a reagent injected from an inlet, is small, the liquid can sequentially flow in the fluidized section  28  due to capillarity or the like without the need of any external powers. If the fluid housing chamber  30  formed in the cylindrical member  20  is used as a measuring section, a liquid can be fed from the fluidized section  28  into the liquid housing chamber  30 , which has a smaller diameter than that of the large-diameter recessed portion  14   a  of the mounting recessed portion  14  which has a diameter equal to each of wells of a microplate, to raise the liquid level, so that the quantity of a reagent to be used can be decreased to reduce costs. 
     Referring to  FIGS. 21A through 21I ,  22 A through  22 F, and  23 A through  23 F, when the injection of a liquid sample into the fluid handling apparatus  10  in this preferred embodiment and the washing of the interior thereof are carried out, the flow of liquid will be described below. 
     First, if a liquid sample  32  is gradually injected from the inlet of the injecting section  26  of the fluid handling subassembly  16  as shown by arrow A in  FIG. 21A , the injected liquid sample  32  is fed into the injecting section  26  as shown in  FIG. 21B . Then, as shown in  FIG. 21C , the liquid sample  32  is fed into the fluidized section  28  via the fluidized section inlets (the cut-out portions  24   a  of the partition plate  24 ), and is fed directly into the slits  20   b  of the cylindrical member  20 . Thereafter, as shown in  FIGS. 21D and 21E , the liquid sample  32  fed into the fluidized section  28  from the fluidized section inlets, and the liquid sample  32  fed into the slits  20   b  are extended so as to be filled in the whole fluidized section  28 , and are extended in the whole slits  20   b  due to capillarity. Until this state, the liquid sample  32  is not fed into the fluid housing chamber  32  by the surface tension of the liquid sample  32  in the slits  20   b . Thereafter, if the liquid sample  32  is further injected as shown by arrow A in  FIG. 21F , the liquid sample  32  is fed along the bottom face of the fluid housing chamber  30  to be stored in the fluid housing chamber  30  after being fed into the injecting section  26  as shown in  FIGS. 21G through 21I . 
     Then, even if the liquid sample  32  is discharged from the fluid handling subassembly  16 , part of the liquid sample  32  adheres to the beads  22  in the fluidized section  28  to remain in the fluidized section  28  as shown in  FIG. 22A . In this state, if a washing solution  34  is injected from the opening of the fluid housing chamber  30  as shown by arrow B in  FIGS. 22B through 22E , the injected washing solution  34  is first fed from the bottom portion of the fluid housing chamber  30  into the slits  20   b  of the cylindrical member  20  as shown in  FIG. 22C . Then, the washing solution  34  is extended in the slits  20   b , and is fed into the fluidized section  28 . Thereafter, if the washing solution  34  is further injected, the liquid sample  32  remaining in the fluidized section  28  is diluted with the washing solution  34  to be pushed up as a mixed solution  36  of the liquid sample  32  and washing solution  34 , which is fed into the injecting section  26  above the fluidized section  28 , as shown in  FIGS. 22D through 22F . 
     Then, a suction pipe (not shown) is inserted into the opening of the fluid housing chamber  30  so as to approach the bottom face of the fluid housing chamber  30  in order to suck the washing solution  34  as shown by arrow C in  FIGS. 23A through 23E . First, as shown in  FIGS. 23A through 23C , the washing solution  34  is sucked, and the most part of the mixed solution  36  fed into the injecting section  26  is fed directly into the fluid housing chamber  30  via the slits  20   b  of the cylindrical member  20  without passing through the fluidized section  28 , so that the mixed solution  36  is further diluted with the washing solution  34 . Thereafter, the washing solution  34  (the mixed solution  36  diluted with the washing solution  34 ) is discharged from the bottom portion of the fluid housing chamber  30 , so that the interior of the fluid handling subassembly  16  is washed. 
     Thus, when the washing solution  34  is injected into the fluid handling subassembly  16  of the fluid handling apparatus  10  in this preferred embodiment, the most part of the mixed solution  36  of the remaining liquid sample  32  and washing solution  34  is pushed up to the injecting section  26  from the fluidized section  28  filled with the beads  22 . Thereafter, when the washing solution  34  is sucked from the fluid handling subassembly  16 , the most part of the mixed solution  36  is fed directly into the fluid housing chamber  30  via the slits  20   b  to be discharged to the outside without passing through the fluidized section  28 . Therefore, it is possible to inhibit the mixed solution  36  from contacting and adhering to the beads  22  in the fluidized section  28  again when the washing solution  34  is sucked, so that it is possible to efficiently wash the interior of the fluid handling subassembly  16  to improve the accuracy of analysis. 
     Second Preferred Embodiment 
       FIGS. 15 through 20  show one of fluid handling subassemblies  16  of the second preferred embodiment of a fluid handling apparatus according to the present invention.  FIG. 15  is a plan view of one of fluid handling subassemblies  16  in this preferred embodiment, which is mounted in a corresponding one of mounting recessed portions  14  of a fluid handling apparatus, and  FIG. 16  is a sectional view taken along line XVI-XVI of  FIG. 15 .  FIG. 17  is a sectional view of a cylindrical member  120  of one of the fluid handling subassemblies  16  of  FIG. 15 , and  FIG. 18  is a side view of the cylindrical member  120  of  FIG. 17 .  FIG. 19  is a sectional view taken along line XIX-XIX of  FIG. 18 , and  FIG. 20  is a sectional view showing a modified example of the cylindrical member  120  of  FIG. 17 . 
     In the fluid handling subassembly  16  in this preferred embodiment, the cylindrical member  120  having no bottom portion is used in place of the cylindrical member  20  with the bottom portion  20   a  of the fluid handling subassembly  16  in the first preferred embodiment. Therefore, no interference fringe occurs between the bottom face of the cylindrical member  120  and the bottom face of the mounting recessed portion  14 , so that the fine recessed portion  14   d  is not formed in the bottom face of the small-diameter recessed portion  14   b . In addition, slits  120   b  extend to the bottom end of the cylindrical member  120  since the cylindrical member  120  has no bottom portion. Moreover, the lid member  25  of the fluid handling subassembly  16  in the first preferred embodiment is not provided. Since other structural portions of the fluid handling subassembly  16  in this preferred embodiment are the same as those of the fluid handling subassembly  16  in the first preferred embodiment, the same reference numbers are given to the same structural portions as those of the fluid handling subassembly  16  in the first preferred embodiment to omit the duplicate descriptions thereof. In addition, since the flow of liquid is the same as that in the first preferred embodiment when the injection of a liquid sample into the fluid handling apparatus  10  in this preferred embodiment and the washing of the interior thereof are carried out, the duplicate descriptions thereof are omitted. 
     Third Preferred Embodiment 
       FIG. 24  is a sectional view showing one of fluid handling subassemblies  16  of the third preferred embodiment of a fluid handling apparatus according to the present invention, which corresponds to  FIG. 9  showing the state that the lid member  25  is removed from the one of the fluid handling subassemblies  16  in the first preferred embodiment. In the fluid handling subassembly  16  in this preferred embodiment, a circular (or another shaped, e.g., rectangular) through hole  14   e , which is smaller than the bottom face of the cylindrical member  20 , is formed in the bottom face of the small-diameter recessed portion  14   b  of the mounting recessed portion  14  in place of the fine recessed portion  14   d  which is formed in the bottom face of the small-diameter recessed portion  14   b  of the mounting recessed portion  14  of the fluid handling subassembly  16  in the first preferred embodiment. In addition, the lid member  25  of the fluid handling subassembly  16  in the first preferred embodiment is not provided. Since other structural portions of the fluid handling subassembly  16  in this preferred embodiment are the same as those of the fluid handling subassembly  16  in the first preferred embodiment, the same reference numbers are given to the same structural portions as those of the fluid handling subassembly  16  in the first preferred embodiment to omit the duplicate descriptions thereof. In addition, since the flow of liquid is the same as that in the first preferred embodiment when the injection of a liquid sample into the fluid handling apparatus  10  in this preferred embodiment and the washing of the interior thereof are carried out, the duplicate descriptions thereof are omitted. 
     In the fluid handling subassembly  16  in the above described first preferred embodiment, the fine recessed portion  14   d  is formed in the bottom face of the small-diameter recessed portion  14   b  of the mounting recessed portion  14  to form a gap for preventing the occurrence of interference fringe between the bottom face of the cylindrical member  20  and the bottom face of the mounting recessed portion  14  when the cylindrical member  20  is fitted into the small-diameter recessed portion  14   b . However, when the fluid handling apparatus  10  in the first preferred embodiment is used for carrying out a method, such as ELISA, if the detection of a target substance is carried out by the determination of absorbance, transmittance is decreased to raise the background value (blank value) in the measurement of absorbance, since the bottom of the fluid handling subassembly  16  has a dual structure which has the bottom of the cylindrical member  20  and the bottom of the mounting recessed portion  14 . For that reason, in the fluid handling subassembly  16  in this preferred embodiment, the through hole  14   e  serving as a light transmitting opening is formed in the bottom face of the small-diameter recessed portion  14   b  of the mounting recessed portion  14  to prevent the blank value (background value) from rising during the measurement of absorbance. In order to confirm this effect, after the fluid handling subassemblies  16  in the first preferred embodiment and this preferred embodiment were used for carrying out ELISA to detect a target substance by the determination of absorbance, each of the fluid handling subassemblies  16  was washed, and then, the same solvent as a reagent was added to each of the fluid handling subassemblies  16  to measure a blank value in the measurement of absorbance with light having a wavelength of 450 nm. As a result, as shown in  FIG. 25 , it was found that the blank value was decreased to 0.45 in this preferred embodiment although the blank value was 0.53 in the first preferred embodiment. 
     Fourth Preferred Embodiment 
       FIG. 26  is a sectional view showing one of fluid handling subassemblies  16  of the fourth preferred embodiment of a fluid handling apparatus according to the present invention, which corresponds to  FIG. 7  showing the one of the fluid handling subassemblies  16  in the first preferred embodiment. In the fluid handling subassembly  16  in this preferred embodiment, a circular (or another shaped, e.g., rectangular) through hole  14   e , which is smaller than the bottom face of the cylindrical member  20 , is formed in the bottom face of the small-diameter recessed portion  14   b  of the mounting recessed portion  14  in place of the fine recessed portion  14   d  which is formed in the bottom face of the small-diameter recessed portion  14   b  of the mounting recessed portion  14  of the fluid handling subassembly  16  in the first preferred embodiment. In addition, the upper portion of each of the slits  20   b  of the cylindrical member  20  of the fluid handling subassembly  16  in the first preferred embodiment (the upper portion of each of the slits  20   b  above the partition plate  24  when the fluid handling subassembly  16  is mounted in the mounting recessed portion  14 ) is widened to be formed as a widened portion  20   c . Since other structural portions of the fluid handling subassembly  16  in this preferred embodiment are the same as those of the fluid handling subassembly  16  in the first preferred embodiment, the same reference numbers are given to the same structural portions as those of the fluid handling subassembly  16  in the first preferred embodiment to omit the duplicate descriptions thereof. Furthermore, the width of the widened portion  20   c  of each of the slits  20   b  of the cylindrical member  20  of the fluid handling apparatus  10  in this preferred embodiment is set as follows. That is, similar to the fluid handling apparatus  10  in the first preferred embodiment, when a liquid sample is injected to the fluid handling apparatus  10  in this preferred embodiment, the liquid sample fed into the fluidized section  28  from the fluidized section inlets (the cut-out portions of the partition plate  24 ) and the liquid sample fed into the slits  20   b  (including the widened portions  20   c ) are extended so as to be filled in the whole fluidized section  28 , and the liquid sample is extended in the whole slits  20   b  (including the widened portions  20   c ) due to capillarity. Until this state, the liquid sample is not fed into the fluid housing chamber  30  by the surface tension of the liquid sample in the slits  20   b  (including the widened portions  20   c ). However, unlike the fluid handling apparatus  10  in the first preferred embodiment, when the fluid handling apparatus  10  in this preferred embodiment is washed, if a larger quantity of washing solution than the quantity of the liquid sample during the injection of the liquid sample is fed into the fluid handling apparatus  10  at a time, the washing solution in the injecting section  26  is fed directly into the fluid housing chamber  30  via the widened portions  20   c  of the slits  20   b . By thus forming the widened portions  20   c  in the slits  20   b , the dirty washing solution discharged above the partition plate  24  from the fluidized section  28  during washing can be smoothly fed into the fluid housing chamber  30  while being prevented from returning to the fluidized section  28 , so that it is possible to decrease the quantity of washing residual in the fluidized section  28 . 
     Also in the fluid handling apparatus  16  in this preferred embodiment similar to the fluid handling apparatus  16  in the above described third preferred embodiment, the through hole  14   e  serving as a light transmitting opening is formed in the bottom face of the small-diameter recessed portion  14   b  of the mounting recessed portion  14  to prevent the blank value (background value) from rising during the measurement of absorbance. In order to confirm this effect, after the fluid handling subassemblies  16  in the first preferred embodiment and this preferred embodiment were used for carrying out ELISA to detect a target substance by the determination of absorbance, each of the fluid handling subassemblies  16  was washed, and then, the same solvent as a reagent was added to each of the fluid handling subassemblies  16  to measure a blank value in the measurement of absorbance with light having a wavelength of 450 nm. As a result, as shown in  FIG. 27 , it was found that the blank value was decreased to 0.35 in this preferred embodiment although the blank value was 0.53 in the first preferred embodiment. Thus, in this preferred embodiment, the blank value can be lower than 0.45 in the third preferred embodiment, so that the blank value can be further decreased by forming the widened portions  20   c  in the slits  20   b . That is, in this preferred embodiment, by thus forming the widened portions  20   c  in the slits  20   b , the dirty washing solution discharged above the partition plate  24  from the fluidized section  28  during washing can be smoothly fed into the fluid housing chamber  30  while being prevented from returning to the fluidized section  28 , so that it is possible to decrease the quantity of washing residual in the fluidized section  28 . Therefore, the blank value can be lower than that in the third preferred embodiment. 
     In the fluid handling apparatus  10  in the first through forth preferred embodiments, the large number of beads  22  are filled in the fluidized section  28  to increase the surface area of the inner surface of the passage in the fluidized section  28 . Therefore, when the fluid handling apparatus  10  is used as a sample analyzing apparatus, if the surface of each of the beads  22  is utilized as a supporting surface (a reaction surface) for supporting thereon a capturing material, it is possible to increase the surface area of the supporting surface (the reaction surface) for the capturing material to increase the contact area with fluid. If liquid is allowed to continuously flow on the large reaction surface, it is possible to enhance the efficiency of reaction, and it is possible to shorten the reaction time and improve the sensitivity of measurement. Furthermore, even if a porous material having continuous holes coated with a capturing material is arranged in the fluidized section  28  in place of the beads  22 , the same advantageous effects can be obtained. 
     In the fluid handling apparatus  10  in the above described first through fourth preferred embodiments, if the fluid handling subassemblies  16  are mounted on each of the fluid handling subassemblies supporting members  13  of the apparatus body  12 , a fluid handling unit, on which the plurality of fluid handling subassemblies  16  are arranged at regular intervals in a row, can be mounted on the frame  11  of the apparatus body  12 . Since the fluid handling unit can be thus mounted on the frame  11  every row, it is possible to easily handle the fluid handling apparatus  10 . 
     In the fluid handling apparatus  10  in the above described first through fourth preferred embodiments, when a washing solution  34  is injected into the fluid handling subassembly  16 , the most part of the mixed solution  36  of the remaining liquid sample  32  and washing solution  34  is pushed up to the injecting section  26  from the fluidized section  28  filled with the beads  22 . Thereafter, when the washing solution  34  is sucked from the fluid handling subassembly  16 , the most part of the mixed solution  36  is fed directly into the fluid housing chamber  30  via the slits  20   b  to be discharged to the outside without passing through the fluidized section  28 . Therefore, it is possible to prevent the mixed solution  36  to contact and adhere to the beads  22  in the fluidized section  28  again when the washing solution  34  is sucked, so that it is possible to efficiently wash the interior of the fluid handling subassembly  16  to improve the accuracy of analysis. 
     While the present invention has been disclosed in terms of the preferred embodiment in order to facilitate better understanding thereof, it should be appreciated that the invention can be embodied in various ways without departing from the principle of the invention. Therefore, the invention should be understood to include all possible embodiments and modification to the shown embodiments which can be embodied without departing from the principle of the invention as set forth in the appended claims.