Abstract:
A coupling for bringing a first conduit in communication with a second conduit. Each of the conduits has an end to be coupled. Each of the conduits is adapted for conducting a fluid. The coupling has a channel adapted for channeling said fluid from said first conduit into said second conduit. Furthermore, the coupling comprises a seal adapted for sealing and receiving said ends of said first and second conduits. The seal is adapted for sealing said channel.

Description:
BACKGROUND ART  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to coupling conduits.  
         [0003]     2. Discussion of the Background Art  
         [0004]     Couplings are used for allowing conduits adapted for conducting a medium to communicate. Known are, for example, light guides or fluid conduits for conducting light or a fluid, for example a liquid. A capillary, for example, can serve as a fluid conduit and as a light guide. Flow cells, for example, for analyzing a fluid can comprise a fluid conduit and a light conduit or better known as a light guide. Flow cells can comprise different conduits communicating via one or more connections.  
         [0005]     U.S. Pat. No. 6,526,188 B2 and the US 2001/0010747 show a modular flow cell having a high optical throughput, a long optical path length and a small cross-section. The modular flow cell configuration includes remote ports or connections for liquid and light input and liquid and light output.  
         [0006]     U.S. Pat. No. 5,444,807 shows a flow-through cell for use in the measurement of chemical properties of small volumes of fluid containing dissolved analytes.  
         [0007]     U.S. Pat. No. 5,608,517 discloses a coated flow cell and a method for making the coated flow cell. The flow cell comprises a flow passage, wherein light directed into the flow cell is internally reflected down the flow passage.  
         [0008]     U.S. Pat. No. 3,236,602 discloses flow cells and holders therefore, the calorimetric examination of a liquid to determine the quantity of a substance present in the liquid.  
         [0009]     U.S. Pat. No. 4,477,186 discloses a photometric cuvette for optical analyses of through-flowing medium, made as a thin and narrow transparent tube requiring minimum sample amounts. Light, substantially parallel to the tube length, is led obliquely into the tube through its wall, is reflected and is led obliquely out through the tube wall to a detector.  
         [0010]     EP 008915781 discloses an optical detector cell for determining the presence of a solute in a sample fluid. The optical detector cell includes a sample tube, inlet and outlet means for the sample fluid, and a first and second optical waveguide for passing a beam of light axially through the sample tube.  
         [0011]     GB 2193313 A discloses an apparatus and method for measuring the spectral absorbance of fluid samples. The length of the light path through the sample is adjusted to optimize the amount of light absorbed by the sample.  
         [0012]     U.S. Pat. No. 6,281,975 B1 shows a bent capillary flow cell with protruding end bulbs coaxial with centerline of an elongated centre cylindrical section of capillary tubing. The bulbs provide a high light throughput entrance window for the cell.  
       SUMMARY OF THE INVENTION  
       [0013]     It is an object of the invention to provide an improved coupling of conduits. The object is solved by the independent claims. Further embodiments are shown by the dependent claims.  
         [0014]     According to embodiments of the present invention, a coupling for bringing a first conduit in communication with a second conduit is suggested. Each conduit comprises an end to be coupled and is adapted for conducting a fluid, for example a gas or a liquid. The coupling comprises a channel. Advantageously, the channel is adapted for channeling the fluid from the first conduit into the second conduit and/or reversed. The channel can be used for fluidically connecting the two conduits. For avoiding any leakage flow, the coupling can comprise a seal.  
         [0015]     Advantageously, the seal can be adapted for receiving the ends of the first and second conduit. By this, the seal can, for example, surround the ends of the conduits in a sealing contact for avoiding any leakage flow of the fluid conducted within the two conduits. Additionally, the seal can be adapted for sealing the channel against any leakage flow towards the environment.  
         [0016]     For this purpose, the seal can surround the ends of the first and second conduits and the channel. For composing the coupling, the ends of the first and second conduits can be inserted into an according breakthrough of the seal, wherein the seal comprises a first aperture adapted for receiving the first conduit and a second aperture adapted for receiving the second conduit, wherein the first and second apertures are fluidically coupled to the channel within the seal or better within an inner loop or breakthrough of the seal.  
         [0017]     Embodiments may comprise one or more of the following: Possibly, the channel can comprise a forking, wherein each branch of the forking is coupled to an aperture or groove. In other words, the coupling or rather the seal of the coupling comprises a plurality of apertures adapted for receiving a plurality of ends of conduits. Possibly, each of the apertures can comprise a groove. Possibly, the seal can comprise a half-shell comprising the channel and the first and second apertures or the plurality of apertures and the forking.  
         [0018]     Embodiments may comprise one or more of the following. The coupling can comprise a support member, wherein the support member is surrounded at least partly by the seal. For this purpose, the support member can comprise the channel and the first and second apertures or the plurality of apertures and the forking. Advantageously, the complete support member comprising the channel connecting the first and second conduits and the ends of the first and second conduits can be sealed by the seal against any.  
         [0019]     The support member can be adapted for positioning and/or supporting the first and second conduits. Advantageously, the outlets of the first and second conduits and the channel itself can be separated from the seal surrounding the support member. By this, it can be avoided that the ends or rather the outlets of the first and second conduits are plugged by the seal.  
         [0020]     Embodiments may comprise one or more of the following. At least one of that said conduits can be adapted for conducting light. Advantageously, the coupling can couple a first fluidic conduit and a second fluidic conduit via the channel, wherein at least one of the fluidic conduits is coupled additionally to the wave guide adapted for conducting light. For example, the first fluidic conduit can comprise a first capillary coupled to a first wave guide by the coupling and the second fluidic conduit can comprise a second capillary coupled to a second wave guide by the coupling. The first and the second wave guides can be arranged coaxially to the according first and second capillary.  
         [0021]     Besides this, the first capillary and the first wave guide can be arranged substantially in a parallel to the second wave guide coupled to the second capillary. For coupling the first and second wave guides to the first and second capillary, optical outlets of the first and second wave guides can be inserted into fluidic outlets of the first and second capillary.  
         [0022]     Further embodiments of the invention relate to a fluidic system. The fluidic system comprises a coupling. Besides this, the fluidic system can comprise a flow cell adapted for housing a fluid sample and for exposing the fluid sample to radiation for analysis and to a fluidic system. The flow cell and the fluidic system can comprise said coupling for bringing a first conduit in communication with a second conduit. Furthermore, the flow cell can comprise two capillaries and two wave guides coupled by the coupling. Advantageously, for example, the capillaries can be connected in series by the coupling. In other embodiments, the capillaries can be fluidically coupled parallel by the coupling.  
         [0023]     Advantageously, the coupling can be used for fluidic systems requiring a low dead volume. Fittings and/or connecting conduits possibly significantly increasing the dead volume are not necessary. A plurality of flow cells can be coupled to a complete fluidic system by the coupling or a plurality of such couplings, wherein just the channel increases the dead volume. For this purpose, advantageously, the channel of the coupling can comprise a relative small-sized cross-sectional area, for example, a similar cross-sectional area as inner tubes of said capillaries providing a fluid path. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     Other objects and many of the attendant advantages of embodiments of the present invention will be readily appreciated and become better understood by reference to the following more detailed description of embodiments in connection with the accompanied drawings. Features that are substantially or functionally equal or similar will be referred to by the same reference signs.  
         [0025]      FIG. 1  shows a 3-dimensional top view of a half shell of a coupling comprising a foil,  
         [0026]      FIG. 2  shows a 3-dimensional top front view of a part section of a coupling comprising a doughnut-shaped seal,  
         [0027]      FIG. 3  shows a cross-sectional view of the coupling of  FIG. 2 , taken along the lines III-III of  FIG. 2 ,  
         [0028]      FIG. 4  shows a cross-sectional view of the coupling of  FIG. 1 , taken along the lines IV-IV of  FIG. 1 ,  
         [0029]      FIG. 4A  shows a detailed view of  FIG. 4  illustrating another embodiment of the coupling,  
         [0030]      FIG. 5  shows a schematic top view of an arrangement of two flow cells, each comprising a fluid path and a light path, wherein the fluid path and the light paths are connected in a counter-current manner,  
         [0031]      FIG. 6  shows a schematic top view of an arrangement of three flow cells connected in series and comprising co-current flow and counter-current flow connected fluid and light paths,  
         [0032]      FIG. 7  shows a schematic top view of an arrangement of three flow cells connected in series and in parallel,  
         [0033]      FIG. 8  shows a schematic top view of an arrangement of three flow cells connected in series, each comprising fluid and light paths coupled in a co-current flow manner,  
         [0034]      FIG. 9  shows a schematic top view of an arrangement of three flow cells, wherein the light paths and the fluid paths are connected in parallel, and wherein the light paths and fluid paths are coupled in a co-current flow manner, and  
         [0035]      FIG. 10  shows a schematic view of a fluidic system comprising two flow cells connected in series. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0036]      FIG. 1  shows a 3-dimensional top view of a coupling  1  comprising a half shell  3  and a seal  5 .  
         [0037]     The coupling  1  is adapted for coupling a first flow cell  7  with a second flow cell  9 . Each of the first and second flow cells  7  and  9  comprises a light path  11  comprising a wave guide  13  and a fluid path  15 , comprising a capillary  17 . The coupling  1  is adapted for fluidically coupling the fluid paths  15  of the first and second flow cells  7  and  9  in series. For this purpose, the coupling  1  or rather the half shell  3  of the coupling  1  comprises a channel  19  adapted for connecting ends  21  of the capillaries  17  of the firstand second flow cells  7  and  9 . The channel  19  can be realized, for example, as a groove of the half shell  3  and can provide a microfluidic fluid path. The channel  19  of the half shell  3  ends up in a first aperture  23  adapted for at least partly receiving the end  21  of the first flow cell  7 . Besides this, the half shell  3  of the coupling  1  comprises a second aperture  25  adapted for at least partly receiving the end  21  of the second flow cell  9 , wherein the channel  19  ends up in the second aperture  25 . The first and second apertures  23  and  25  can be realized, for example, as half-pipe-shaped grooves of the half shell  3 . Aperture can be understood as a half-pipe-shaped groove. Besides this, aperture can be understood as a combination of two opposed mounted half-pipe-shaped grooves, wherein the two grooves can be combined to a substantially circular shaped opening or aperture. For this purpose, the half shell  3  can be combined with a cover shell  31  as shown in  FIG. 3  and  4 .  
         [0038]     Advantageously, the coupling  1  and the flow cells  7  and  9  coupled by the channel  19  can be integrated in one device, wherein any dead volume and the total amount of component parts can be reduced to a minimum. Besides this, the channel  19  can be branched or better can comprise a forking for providing a splitting device for the fluid path  15 . Consequently, the splitting device can also be integrated in said one device.  
         [0039]     Furthermore, the half shell  3  comprises two recesses  27  adapted for at least partly receiving the capillaries of the first and second flow cells  7  and  9 , wherein between the outer surfaces of the capillaries  17  of the first and second flow cells  7  and  9  and the recesses  27  remains an air gap  29 .  
         [0040]      FIG. 4  shows a cross-sectional view of the half shell  3  of the coupling  1  of  FIG. 1  together with the cover shell  31  of the coupling  1 , taken along the lines in IV-IV of  FIG. 1 . In the following, by referring to the  FIG. 1  and  4 , the design of the seal  5  of the coupling  1  is described.  
         [0041]     The seal  5  comprises a foil  33  surrounding the channel  19 . The foil  33  of the seal  5  of the coupling  1  can be doughnut-shaped, wherein the channel  19  lays in an inner loop  35 . The inner loop  35  can be realized as a break-through within the foil  33 .  
         [0042]     Possibly, the inner loop  35  of the seal can be used for conducting the fluid between the flow cells  7  and  9 . The shells  3  and  31  can be joined together via the seal  5  in a small distance to each other. By this, the seal  5  can provide the channel of the coupling  1 , wherein the clearance between the shells  3  and  31  within the loop of the seal  5  provides a fluid path between the flow cells  7  and  9 . Consequently, if desired, the groove scribed in at least one of the shells  3  and  31  can be dropped. Furthermore, the inner loop  35  of the seal  5  can be reduced to a small slit or groove providing the channel of the coupling  1 . Finally, the seal can  5  be extended to a layer or a plurality of layers adapted to the size of the surfaces  43  and  41  of the shells  3  and  31 . At least one of said layers can comprise the channel. The shells  3  and  31  can be joined together via the seal  5  in a small distance to each other.  
         [0043]     As shown in  FIG. 4 , the foil  33  of the seal  5  comprises a top layer  37  and a bottom layer  39 . The top layer  37  of the seal  5  is coupled in a fluid-tight manner to a surface  41  of the cover shell  31 . The bottom layer  39  is coupled in a fluid-tight manner to a surface  43  of the half shell  3  of the coupling  1 . The half shell  3  and the cover shell  31  can be substantially symmetrically designed. By this, the first and second apertures  25  of the coupling I are realized by according grooves of the half shell  3  and the cover shell  31 . For realizing a complete fluid-tight seal  5  for the channel  19  and the first and second flow cells  9 , the top layer  37  and the bottom layer  39  are additionally in a sealing contact with spans  45  of the according grooves of the first and second apertures  25  of the half shell  3  and the cover shell  31 .  
         [0044]     Summarizing, the top layer  37  and the bottom layer  39  are in contact with each other in a fluid-tight manner. Besides this, the top layer  37  and the bottom layer  39  are in contact with the according outer surfaces of the capillaries  17  and the wave guides  13  of the first and second flow cells  7  and  9 , the spans  45  of the grooves of the first and second apertures  23  and  25 , and with the half shell  3  and the cover shell  31 , each in a fluid-tight manner.  
         [0045]     For realizing the fluid-tight sealing contact of the top layer  37  and the bottom layer  39  with the according components of the coupling  1  and with each other, the half shell  3  and the cover shell  31  can be pressed to each other, for example, by screws, by a clamping device, hydraulic forces, and/or alike. Possibly, the top layer  37  and the bottom layer  39  can comprise a foil  33  that can be activated by heating, for example by executing a heat sealing process. Besides this, the sealing contact of the top layer  37  and the bottom layer  39  can be realized by adhesives.  
         [0046]      FIG. 4A  shows a detail of  FIG. 4  showing the seal  5  in a sealing contact with the surfaces  41  and  43  of the shells  31  and  3  of the flow cell  1 . As shown in  FIG. 4A , possibly, the seal  5  can be embedded in recesses  46  of the shells  31  and  3 . Possibly, the recesses  46  can slightly less deep as the thickness of the layers  37  and  39  of the foil  33  of the seal  5 . By varying said deepness of the recesses  46  and the thickness of the layers  37  and  39 , the sealing forces of the seal  5  can be adjusted and/or limited. Furthermore, by this, the surfaces  41  and  43  of the cover shell  31  and the half shell  3  can be flushly joined together.  
         [0047]      FIG. 2  shows a 3-dimensional top front view of a part section of a coupling  1  comprising a doughnut-shaped seal  1 . The seal  1  of the coupling  1  comprises a plastic material  47 . The plastic material  47  of the seal  1  is shown partly in  FIG. 2 . The plastic material  47  of the coupling  1  comprises, for example, an elastic material.  
         [0048]     Furthermore, the plastic material can comprise, an elastomeric material, a thermoplastic material, polyetheretherketone (PEEK), one of a broad range of flouropolymeres, in particular perfluoroamines (PFA) or flourinated ethylen-propylene copolymer (FEP), duroplastic material or compound, in particular polyimide, liquid crystal polymers (LCP), and/or alike.  
         [0049]     For realizing the seal  5  of the coupling  1  as shown in  FIG. 2 , the plastic material  47  can be injected as a fluid into circular or doughnut-shaped recesses  49  of the half shell  3  and the cover shell  31  of the coupling  1 . For this purpose, the cover shell  31  of the coupling  1  can comprise an injection channel  51  and a mold vent channel  53 . In further embodiments, plastic material can simply be inserted into the recesses  49 . For assembling the coupling  1 , the wave guides  13  and the capillaries  17  of the first and second flow cells  7  and  9  can be inserted into apertures  55  of the plastic material  47  of the seal  5 .  
         [0050]      FIG. 3  shows a cross-sectional view of the coupling  1  of  FIG. 2 , taken along the lines III-III of  FIG. 2 . As can be seen in  FIG. 3 , the cross sections of the recesses  49  of the cover shell  31  and the half shell  3  of the coupling  1  are rectangular shaped. Possibly, the cross sections of the recesses  49  can comprise any other shape; can be, for example, half-pipe-shaped. Possibly, the recesses  49  of the shells  3  and  31  can comprise undercuts  56  for improving the sealing effect, as exemplarily shown on the left hand side of  FIG. 3  by dashed lines. The plastic material  47  of the seal  5  being located in the recesses  49  surrounds the channel  19  of the coupling  1 , wherein a sealing effect is realized at the surfaces of the recesses  49  and the outer surfaces of the wave guides  13  and the capillary  17  of the first and second flow cells  7  and  9  at the spans  45  of the capillaries  17  and the wave guides  13 . By this, any fluid leakage toward the outside of the coupling  1  can be avoided by the seal  5 . As can be seen in the  FIG. 3  and  4 , the cover shell  31  also comprises a channel  19  being oppositely arranged to the channel  19  of the half shell  3  of the coupling  1 . Possibly, just one of the shells  3  or  31  comprises a channel  19 .  
         [0051]     For connecting the light paths  11  and the fluid paths  15  of the first and second flow cells, the optical outlets of the wave guides  13  are inserted into inner tubes  57  of the according capillaries  17 . By this, the fluid conducted within the capillaries  17  of the first and second flow cells  7  and  9  can be irradiated by the optical outlets of the wave guides  13 .  
         [0052]     The elastic or elastomeric material can be pressurized by at least one pin inserted into one of the channels  51  or  53  of the cover shell  31  leading into the recesses  49  forming a cavity.  
         [0053]     Possibly, said seal can comprises a low pressure seal comprising the solvent resistant material, for example, an elastomeric material and a high pressure seal comprising an adhesive which is not in contact with the solvent or fluid.  
         [0054]      FIG. 5  shows a schematic top view of an arrangement of the first and second flow cells  7  and  9  being connected by the coupling  1 . The capillaries  17  of the first and second flow cells  7  and  9  as shown in  FIG. 5  are fluidically coupled in series. The light paths  11  of the first and second flow cells  7  and  9  are connected in parallel. Each of the first and second flow cells  7  and  9  are operated in a counter-current flow manner. Operating a flow cell in a counter-current flow manner can be understood as sending the light of the light path  11  of the flow cell in the opposite direction through the capillary  17  as the fluid within the inner tube  57  of the capillary  17 .  
         [0055]     The direction of the light guided through the wave guides  13  and the capillaries  17  are indicated by arrows  59 . The flow direction of the fluid paths  15  of the flow cells  7  and  9  are indicated by arrows  60 . Besides this, different beams of the light paths  11  of the first and second flow cells  7  and  9  are indicated by a plurality of lines  61 .  
         [0056]     As shown in  FIG. 5 , within the wall of the capillaries  17 , at the transition of the outer surface of the capillary  17  and the air gap  29  ( FIG. 1  or  FIG. 2 ), total reflection of the beams—as indicated with the lines  61 —occurs. The light of the light paths  11  can be guided though a fluid conducted within the inner tubes  57  of the first and second flow cells, wherein the fluid can comprise a sample to be analyzed.  
         [0057]      FIG. 6  shows a schematic top view of an arrangement of a first flow cell  63 , a second flow cell  65  and a third flow cell  67 . The fluid paths  15  of the flow cell  63 ,  65  and  67  of the arrangement as shown in  FIG. 6  are fluidically connected in series by a first coupling  1  and a second coupling  1 , for example, as shown in the  FIG. 1-4 . The light paths  11  of the three flow cells  63 ,  65  and  67  of the arrangement are connected in parallel. Each of the light paths  11  can be connected with a not shown light source adapted for coupling light into the light paths  11 . On the other side, in direction of  FIG. 6  right hand sided, the light paths  11  can be coupled to not shown detectors adapted for determining the amount of light guided through the flow cells  63 ,  65  and  67 .  
         [0058]     For metering fluid into the fluid paths  15  of the flow cells  63 ,  65 ,  67 , an inlet port  69  of the first flow cell  63  can be coupled to a not shown fluid source, for example a pump, a nanopump, and/or alike. Accordingly, an outlet port  71  of the third flow cell  67  can be coupled to a waste or to an arbitrary downstream device. In difference to the arrangement of  FIG. 5 , the flow cells  63 ,  65  and  67  are operated in a combined flow manner, wherein the first flow cell  63  and the third flow cell  67  are operated in a counter-current flow manner and the second flow cell  65  is operated in a co-current flow manner. Co-current flow manner can be understood as operating a flow cell in a way that the light and the fluid is guided through the flow cell in the same direction.  
         [0059]      FIG. 7  shows a schematic top view of an arrangement of a first flow cell  73 , a second flow cell  75 , and a third flow cell  77 . The flow direction of the fluid paths  15  of the flow cells are indicated by arrows  60 .  
         [0060]     In difference, the first flow cell  73  and the second flow cell  75  are fluidically connected in parallel. For this purpose, the fluid path  15  of the arrangement as shown in  FIG. 7  can comprise a forking device  79  for manifolding the flow into the first and second flow cells  73  and  75 . The forking device  79  can be analogously designed as on of the couplings  1  of one of the FIGS.  1  to  4 .  
         [0061]     The first flow cell  73  can be coupled downstream to a not shown waste or an additional device. The second flow cell  75  is fluidically coupled downstream to the third flow cell  77 . In other words, the second flow cell  75  and the third flow cell  77  are fluidically coupled in series, wherein the third flow cell  77  can be coupled downstream to a waste or to a not shown additional device.  
         [0062]     The light path  11  of the arrangement or rather of the first, second, and third flow cell  73 ,  75  and  77  is branched. Therefore, the arrangement comprises a light manifolding device  81 . For this purpose, the light manifolding device  81  can comprise a semi-transparent mirror  83  adapted for splitting the light beam and a mirror  85 . The light path  11  conducted through the first flow cell  73  is forked in two light paths  11  of the second flow cell  75  and the third flow cell  77 . By this, the second flow cell  75  and the third flow cell  77  or rather the wave guides  13  of the second and third flow cells  75  and  77  can be coupled to a not shown light detector. The direction of the light directed through the light paths is indicated by the arrows  59 .  
         [0063]     The first flow cell  73  and the third flow cell  77  are operated in a co-current flow manner. The second flow cell  75  is operated in a counter-current flow manner.  
         [0064]      FIG. 8  shows a schematic top view of an arrangement of three flow cells  63 ,  65 , and  67 . In difference to the arrangement as shown in  FIG. 6 , all flow cells  63 ,  65 , and  67  are operated in a co-current flow manner. The forking device  79  can be analogously designed as on of the couplings  1  of one of the FIGS.  1  to  4 .  
         [0065]      FIG. 9  shows an arrangement of three flow cells  63 ,  65 , and  67 . In difference to the arrangements as shown in  FIG. 6  and  FIG. 8 , the arrangement of  FIG. 9  comprises three flow cells  63 ,  65 , and  67  fluidically coupled in parallel. For this purpose, the fluid paths  15  of the arrangement of  FIG. 9  comprises a forking device  79  comprising three branches  87 , wherein each of the three flow cells  63 ,  65 , and  67  is coupled to one of the branches  87  of the forking device  79 . The flow cells  63 ,  65 , and  67  are operated in a co-current flow manner. By this, additionally, the forking device  79  can couple the capillaries  17  and the wave guides  13  of the flow cells  63 ,  65 , and  67  of the arrangement as shown in  FIG. 8 .  
         [0066]     Advantageously, undesired side effects, for example caused or influenced by the direction of the streaming fluid and/or variation of the composition of the fluid, can be reduced, compensated and/or eliminated by accordingly arranging the flow cells, for example as shown in the Fig. above, and evaluating the signals of coupled detectors.  
         [0067]      FIG. 10  shows a fluidic system  201  comprising a fluid source  203 , for example a pump, a nanopump, and/or alike, and a fluid sink  205 , for example a waste or a downstream coupled device, for example for analysis purposes.  
         [0068]     Between the fluid source  203  and the fluid sink  205 , the fluidic system  201  comprises a fluid path  207 . The fluid path  207  is coupled with at least one light path  209 . Possibly, the fluid path  207  of the fluidic system  201  can be coupled with a second light path  211 . The fluid path  207  and the first and second light paths  209  and  211  belong to a first and a second flow cell  213  and  215 .  
         [0069]     For coupling the fluid path  207  and the first and second light paths  209  and  211 , the fluidic system  201  comprises at least one coupling  217 . The coupling  217  can be realized according to one of the couplings according to the Figures above.  
         [0070]     Each of the flow cells  213  and  215  comprises a capillary  219  and comprises a wave guide  221 . The capillaries  219  of the first and second flow cells  213  and  215  are adapted for conducting a fluid, for example, a fluid comprising a sample, for example, a sample dissolved in a liquid. For analyzing the sample of the fluid, the fluid can be irradiated by the wave guides  221  of the light paths  209  of the first and second flow cells  213  and  215 . For measuring the amount of light guided through the fluid sample, the light paths  209  can be connected to not shown light detectors.  
         [0071]     The wave guide  221  can also be an optical element like a window, glass rod, and/or alike.  
         [0072]     Furthermore, the coupling/s  217  can comprise a plurality of communicating branches, for example, for coupling the capillaries  219 , the wave guides  213 , and/or according supplying or rather draining conduits to each other.  
         [0073]     The direction of the light guided though the light paths  209  of the first and second flow cells  213  and  215  is indicated by arrows  223 . The direction of the fluid guided though the fluid paths  207  of the first and second flow cells  213  and  215  is indicated by arrows  225 . Besides this, different beams of the light paths  209  are indicated by lines  231 .  
         [0074]     The capillaries  219  of the first and second flow cells  213  and  215  can comprise a transparent material, for example glass, quartz glass, and/or alike, wherein within the walls of the capillaries total reflection can occur as shown by the beams as indicated by the lines  231  of  FIG. 10 .  
         [0075]     The fluid source  203  can comprise a separating device  227  and/or can be coupled with such a device. Besides this, the fluid sink  205  can comprise an analyzing device  229 , for example, a mass spectrograph. The fluidic system  201  can be realized as an integrated system for analysis purposes, for example as a integrated system commercially available, for example, a chromatographic system (LC), a high performance liquid chromatographic (HPLC) system, an HPLC arrangement comprising a chip and an mass spectrograph (MS), a high throughput LC/MS system, a purification system, a micro fraction collection/spotting system, a system adapted for identifying proteins, a system comprising a GPC/SEC column, a nanoflow LC system, and/or a multidimensional LC system adapted for separation of protein digests.  
         [0076]     The fluidic system  201  can be adapted for analyzing liquid. More specifically, the fluidic system  201  can be adapted for executing at least one microfluidic process, for example an electrophoresis and/or a liquid chromatographic process, for example a high performance liquid chromatographic process (HPLC). Therefore, the fluidic system  201  can be coupled to a liquid delivery system, in particular to a pump, and/or to a power source. For analyzing liquid or rather one or more components within the liquid, the fluidic system  201  can comprise a detection area, such as an optical detection area and/or an electrical detection area being arranged close to a flow path within the fluidic system  201 . Otherwise, the fluidic system  201  can be coupled to a laboratory apparatus, for example to a mass spectrometer, for analyzing the liquid. For executing an electrophoresis, the flow path can comprise a gel. Besides this, the fluidic system can be a component part of a laboratory arrangement.  
         [0077]     It is to be understood, that this invention is not limited to the particular component parts of the devices described or to process steps of the methods described as such devices and methods may vary. It is also to be understood, that different features as described in different embodiments, for example illustrated with different Fig., may be combined to new embodiments. It is finally to be understood, that the terminology used herein is for the purposes of describing particular embodiments only and it is not intended to be limiting. It must be noted, that as used in the specification and the appended claims, the singular forms of “a”, “an”, and “the” include plural referents until the context clearly dictates otherwise. Thus, for example, the reference to “a coupling” or “a fluid path” may include two or more such functional elements.