Patent Publication Number: US-11045802-B2

Title: Sample carrier

Description:
The present application is a 371 of International application PCT/EP2016/060498, filed May 11, 2016, which claims priority of EP 151 73 174.2, filed Jun. 22, 2015, the priority of these applications is hereby claimed and these applications are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a sample carrier with a region for receiving a sample that is to be analyzed, in particular a biological sample, the volume of the sample being between 1 and 100 μl, and with a region for handling the sample carrier. The invention further relates to an analysis device, in particular a flow cell, with such a sample carrier. 
     WO 2005/094681 A1 discloses a sample carrier for receiving a biological sample, with a capillary taking up a dosed quantity of the sample. The capillary is adjoined by a cylinder space in which a piston for ejecting the sample from the capillary is movable via an air cushion. While the sample is being taken up by the capillary, an opening channel ensures venting of the cylinder. With the displacement of the piston in the cylinder, this opening channel closes. 
     WO 00/74853 A1 describes a sample carrier which is combined with a closure element for a container. With the closure of the container by the closure element, a biological sample, for example, enters the container interior, where it is screened off from the external environment and comes into contact with a diluting liquid. The diluted sample is then to be removed from the container and delivered for analysis. 
     SUMMARY OF THE INVENTION 
     The present invention makes available a novel sample carrier of the type mentioned at the outset, which sample carrier is characterized by devices with which the sample carrier containing the sample is connected in a fluid-tight manner to the sample in an analysis device. 
     Advantageously, a sample that is to be analyzed is supplied to the analysis process by the sample carrier according to the invention directly by the shortest route. The sample, e.g. a body fluid such as blood, urine and saliva, a food sample or an environmental sample, in particular a water sample, is no longer introduced into a flow cell via an input port that is to be closed after the introduction; instead the introduction of the sample into the analysis process is completed with the fluid-tight placement of the sample carrier carrying the sample quantity, optionally already dosed. It is possible to dispense with sample dosing inside the flow cell. 
     In a particularly preferred embodiment of the invention, the sample placed together with the sample carrier in the analysis device adjoins a cavity in the analysis device involved in the analysis, in particular in a flow cell, and the sample carrier closes the cavity off from the outside in a fluid-tight manner. Advantageously, with the placement of the sample carrier, the flow cell for example is automatically closed by the sample carrier itself. It goes without saying that the cavity can also be filled with a material that takes up liquid, e.g. a nonwoven or a porous membrane. 
     The abovementioned cavity can be, for example, a transport channel or a chamber, in particular a mixing chamber. 
     In another preferred embodiment of the invention, the sample placed together with the sample carrier in the analysis device can be detached from the sample-receiving region by a stream of fluid. The fluid can be both a flushing liquid and also a gas, in particular compressed air. 
     The abovementioned stream of fluid can be generated, for example, by emptying of a reagent reservoir integrated in the analysis device or connected in a fluid-tight manner to the analysis device, wherein, for example, a deformation of the reservoir space of the reagent reservoir is effected by actuation. 
     In a further embodiment of the invention, the sample carrier itself can have devices with which the sample to be analyzed is transported away from the sample carrier, e.g. a flushing channel extending through the sample carrier and guiding a flushing liquid or a flushing gas. 
     In another particularly preferred embodiment of the invention, the sample carrier has devices for pre-processing of delivered sample material. The sample to be analyzed is formed from this in the course of the pre-processing. 
     The pre-processing devices preferably comprise means for dosing the sample material, reagent means and/or separating means, in particular for separation of blood plasma. 
     The sample carrier expediently covers in a fluid-tight manner an opening leading into the cavity; in particular it can be inserted into the opening and preferably closes the opening like a stopper. 
     In a particularly preferred embodiment of the invention, an interference fit for the sample carrier is formed by the opening, wherein the sample carrier in particular has a cone corresponding to a Luer lock. 
     The sample carrier closing the opening like a stopper can be rotatable in the opening while maintaining fluid-tight closure. 
     It goes without saying that the sample carrier is produced, preferably in one piece, as a plastic injection-molded part, optionally with several sample-receiving regions formed on one sample carrier. 
     Preferably, the receiving region itself has means for receiving the sample in a dosed quantity, for which purpose, in addition to geometric boundaries of the sample-receiving region, it is possible to consider primarily surface coatings and/or locally used plastic materials for controlling the wettability of the receiving region, in particular in such a way that the sample-receiving region is selectively wettable with sample material. 
     Preferably, the handling region permits manual handling of the sample carrier without touching the sample. 
     The handling region can be a handle which, after placement of the sample carrier in the analysis device, can be broken away from the rest of the sample carrier at a predetermined breaking point. 
     In a further embodiment of the invention, the sample carrier can have a closure device which prevents removal of the positioned sample carrier from the analysis device, e.g. a snap-fit fastener or the like. 
     In a further embodiment, the receiving region of the sample carrier comprises a dry reagent, if appropriate for a first reaction with the sample. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The invention is explained in more detail below on the basis of illustrative embodiments and with reference to the attached drawings which relate to these illustrative embodiments and in which: 
         FIG. 1  shows a flow cell according to the invention in a perspective view, with and without a sample carrier, 
         FIG. 2  shows the flow cell from  FIG. 1  in a perspective view from below, with a sample carrier mounted on the flow cell, 
         FIG. 3  shows the sample carrier used in the flow cell of  FIGS. 1 and 2 , in a perspective view and in axial section, 
         FIG. 4  and  FIG. 4 a    are views illustrating how a sample is received by the sample carrier of  FIGS. 1 to 3 , 
         FIG. 5  shows different sample carriers according to the invention in sectional partial side views and in views from below, 
         FIG. 6  shows a sample carrier according to the invention with a flushing channel and with a sample-receiving region formed by a capillary, 
         FIG. 7  shows a sample carrier according to the invention with a flushing channel and with a conical capillary receiving region, 
         FIG. 8  shows a sample carrier according to  FIG. 6  with an end constriction of the capillary, 
         FIG. 9  and  FIG. 9 a    show a sample carrier according to the invention, with a flushing channel opening out at each of the ends of a cone, 
         FIG. 10  shows examples for the connection of a sample carrier according to the invention to different regions of a flow cell, 
         FIGS. 11 and 12  show the sample carriers from  FIGS. 6 and 9  in conjunction with a flow cell, 
         FIG. 13  shows different sample carriers according to the invention with different sample-receiving regions, 
         FIG. 14  shows sample carriers according to the invention with different handling regions, 
         FIG. 15  shows a further sample carrier according to the invention for the pre-processing of a blood sample by separation of blood plasma, 
         FIG. 16  shows a sample carrier according to the invention with a passage serving as a venting and flushing channel, 
         FIG. 17  shows the sample carrier from  FIG. 16  in conjunction with a handling appliance, 
         FIG. 18  shows the sample carrier from  FIG. 16  in conjunction with a handling appliance modified in relation to the handling appliance from  FIG. 17 , 
         FIG. 19  shows a partial view of a further sample carrier according to the invention which can be manipulated by the handling appliance from  FIG. 18 , 
         FIG. 20  shows a rotatable dosing element, 
         FIG. 21  shows a flow cell provided for cooperation with the dosing element from  FIG. 20 , and 
         FIG. 22  shows an arrangement consisting of the dosing element from  FIG. 20  and the flow cell from  FIG. 21  in different working positions of the dosing element. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A flow cell comprises an injection-molded plastic substrate  1 , a laminate film  2  with layers of aluminum and plastic, and also a cover film  3  on the side of the substrate  1  facing away from the laminate film  2 . 
     In the substrate  1 , chambers and channels are formed, e.g. the chamber  4  and the channel  5 . Bulges of the laminate film  2  form reservoir spaces  6 . 
     As can be seen from  FIG. 1 a   , a sample carrier  7  is arranged on a chamber wall  16  forming the chamber  4 , which sample carrier  7  is screwed onto a stub  12  which protrudes from the chamber wall  16  and which has threaded projections  13 . 
     The sample carrier  7  comprises a conical support element having a sample-receiving region  9  at a free front end thereof. The support element  8  protrudes from the bottom of a pot-shaped rotary handle part  10  with an internal thread  11 , into which the threaded projections  13  engage, and with rib projections  14 . As can be seen from  FIG. 2 , the sample-receiving region  9  of the sample carrier  7  screwed onto the stub  12  projects into the chamber  4 . In order to introduce a sample to be analyzed into the flow cell, sample material  15  is applied, according to  FIG. 4 , to the sample-receiving region  9 . In the example shown, the sample-receiving region  9  comprises a groove  18  which is open on three sides and in which there remains a sample quantity held by capillary forces. The user, holding the sample carrier  7  at the rotary handle part  10 , does not come into contact with the sample quantity when introducing the sample quantity into the flow cell by screwing the sample carrier  7  onto the stub  12 . During said screwing, the conical support element  8  forms a fluid-tight interference fit with the conical inner surface of the stub  12 . 
     When supplying liquid sample material  15  to the receiving region  9  in accordance with  FIG. 4 , a defined sample quantity is measured out that remains in the groove  18  open on three sides. This is done, for example, by dipping the receiving region  9  into an openly accessible sample droplet, which can be located, for example, at the outlet of a syringe, in a container such as a microtiter plate, or, specifically in the case of blood as sample material, also on the skin of a patient, e.g. on a finger pad  70  in accordance with  FIG. 4 a   . Alternatively, the sample material can also be pipetted on or dropped on. Critical factors in the measuring of a defined sample quantity are, on the one hand, the geometric shape of the groove  18 , the walls of which form boundaries. In the example in question, the cross section of the groove is ca. 2×2 mm 2 . Reproducible measurement of a sample quantity is permitted, on the other hand, by a coating that is provided in the receiving region  9  and determines the wettability of the groove walls. For example, blood or other aqueous samples as fluid sample material fill the groove by capillary action, in which case, on account of the hydrophilic wetting properties, a defined blood sample quantity is measured. 
     The blood sample quantity bound by capillary forces remains adhering in the receiving region  9  and is introduced into the chamber  4  with the aid of the sample carrier  7 , as has been described above. In the course of an analysis that is to be carried out, the sample is flushed from the sample carrier. 
     A sample carrier corresponding to the sample carrier  7  is shown in  FIG. 5 a   . The groove  18 , open on three sides, receives a defined sample quantity  17 . 
       FIGS. 5 b  to 5 g    illustrate further possibilities for the formation of receiving regions  9  of the above-described sample carrier  7 . 
       FIG. 5 b    shows a receiving region in the form of a pocket-shaped recess  19  in the end face of the conical support element  8 . A sample quantity  20  in droplet form is formed reproducibly through the recess  19 . 
       FIG. 5 c   , like  FIG. 5 b   , relates to a receiving region in the form of a circular recess. However, the preferably hydrophilized recess has a microstructure that enlarges the wetting surface, e.g. columns  21  protruding from the bottom of the recess. A network of the column arrangement measures between 10 and 500 μm, preferably between 20 and 200 μm. The microstructure leads to improved wetting properties and better control of droplet formation, hence further improved reproducibility of the sample quantities. 
       FIG. 5 d    shows a receiving region which is formed by a serpentine groove channel  22 , open at its ends, in the end wall of the conical support element. In the example shown, the cross section of this channel measures 0.2×0.2 mm 2 , preferably between 0.1 and 0.5 mm 2 . The smaller cross-sectional dimensions of the optionally hydrophilically modified channel permit better control of the wettability and therefore of the reproducibility of the measured sample quantity. 
     An illustrative embodiment shown in  FIG. 5 e    is identical to the example in  FIG. 5 d    except for a cover film  23  which is arranged on the end face of the conical support element and which forms one part of the in this case two-part sample carrier. The groove channel  22  closed by the cover film  23  is filled by capillary action via an open end, as a result of which, in particular by partial or complete hydrophilic modification, a sample quantity can be measured very precisely since the capillary filling at the respective other end of the channel terminates by itself. In order to flush out the metered sample quantity, a flushing device with a targeted action is preferably used in the analysis appliance. 
     A further two-part sample carrier with a through-hole  24  as receiving region has a permeable membrane  25  closing the through-hole at one end. The membrane has pores of such a size that they are permeable to gas but not to liquid. The air permeability of the membrane  25  permits capillary filling of the through-hole  24 . 
     An embodiment with the same function but without a permeable membrane  25  is likewise conceivable. 
     To empty this sample carrier in an analysis device, a pneumatic or hydraulic pressure is applied to the side covered by the membrane. 
     Another two-part sample carrier is shown in  FIG. 5 g   . A sample-receiving region is formed by an absorbent nonwoven  26  applied to the end face of the conical support element. The nonwoven  26  takes up sample liquid by capillary action. 
     In an analysis device, the sample can be released by squeezing the nonwoven or it can be flushed out with the aid of a flushing liquid. The sample can also be supplied for the analysis process by being brought into contact with a lateral flow membrane, where it is sucked out of the nonwoven  26  of the sample carrier by the capillary action of lateral flow membrane. This process can be supported by a flushing liquid which is transported through the lateral flow membrane. 
     Reference is now made to  FIG. 6 , where a two-part sample carrier is shown which comprises a conical support element  27  having a through-hole  28 . The through-hole  28 , which can be filled with sample material by capillary action, terminates at a flushing channel  30  delimited by a film  29 . The capillary filling of the through-hole  28  terminates automatically at the flushing channel  30 . The flushing channel  30  leads through a further cone  31 . By way of the conical support element  27  and the cone  31 , the sample carrier can be connected to a flow cell, where a measured sample quantity  32  can be flushed hydraulically or pneumatically out of the through hole  28 . 
       FIG. 7  shows an illustrative embodiment which differs from the illustrative embodiment of  FIG. 6  in that, instead of a through-hole  28  with an approximately constant cross section, a conically widening through-hole  34  is formed. In this way, a larger sample quantity  33  can be taken up in a smaller space. The smaller end opening of the through-hole  34  permits better reproducibility of the sample quantity that is taken up. Typical diameters at the narrowest point are between 0.1 and 0.3 mm. At the widest point, the diameter can be between 0.5 and 2 mm, while the length of the through-hole  34  is typically from 2 to 10 mm. 
     By varying the diameters or the volume of the sample-receiving region, different sample volumes can be introduced effectively into a microfluidic flow cell, and the measured quantities thus adapted to the requirements of different analyses and/or samples, simply by exchange of the sample carrier, with the external dimensions remaining the same. 
     A sample carrier shown in  FIG. 8  is identical to the sample carrier from  FIG. 6  except for a constriction  35  of its through-hole  28  at its end directed toward the flushing channel  30 . The constriction  35  of the sample carrier in  FIG. 8  forms a capillary stop that limits the capillary filling of the sample-receiving region with particular precision. The reproducibility of the measurement of samples is correspondingly high. In relation to the diameter of the through-hole  28 , the dimensions of the constriction are typically reduced by 10 to 50%. The thickness of the lip forming the constriction is typically from 0.02 to 0.2 mm. 
       FIG. 9  concerns a sample carrier which, compared to the sample carrier in  FIG. 8 , is extended by a further cone  36  and has a flushing channel  37  with two inlets  38  and  39 . In the sample carrier of  FIG. 9 , it is advantageously possible to prevent the formation of an air cushion upstream from the flushing liquid in the direction of flow, since the flushing liquid is first introduced from the inlet  38  to the inlet  39  and, in this way, all the air is removed from the flushing channel  37 . The inlet for the sample is blocked by a valve (not shown). To flush out a sample quantity  40 , the valve is opened, and a valve (not shown) at the inlet  39  is closed. The flushing liquid flowing through the inlet  38  now transports the sample quantity  40  from the sample-receiving region. 
     A sample carrier shown in  FIG. 9 a   , and similar to the sample carrier of  FIG. 9 , has three conical plug elements, with which it can be plugged onto a flow cell. The central plug element forms a sample-receiving region with a widening receiving space  71  for receiving a blood sample. The receiving space  71 , fillable by capillary action and having hydrophilically coated walls, is delimited, at its end facing away from an opening, by a plasma separation membrane  72 , which limits the quantity of blood sample taken up. 
     The plasma separation membrane  72  adjoins a channel  74  which is coated hydrophilically on the inside and covered by a film  73 , the ends of the channel  74  being connected, in each case via a constriction  75 ,  76 , to a flushing channel  77 ,  78  which leads through an outer plug element. In the example shown, the volume of the receiving space  71  is about 2½ times as great as the volume of the channel  74 . 
     In the state in which the sample carrier shown in  FIG. 9 a    is plugged onto a flow cell, the central conical element terminates in a blind hole, such that the receiving space  71  is closed. Plasma of the blood sample received in the receiving space  71  passes through the plasma separation membrane  77  into the channel  74 , which fills by capillary action, wherein the constrictions  75 ,  76  each form a capillary stop, such that a precisely measured quantity of plasma fills the channel  74 . By way of the flushing channels  77 ,  78 , this quantity of plasma can be flushed out by a flushing liquid or a flushing gas and supplied for processing inside the flow cell. In addition to having the function of receiving the sample, the sample carrier shown in  FIG. 9 a    thus has the function of pre-processing the sample. 
       FIG. 10  illustrates possible ways of connecting a sample carrier to different functional regions of a flow cell. 
     According to  FIG. 10 a   , the receiving region of a sample carrier protrudes with a conical support element into a mixing chamber  41  of a flow cell, wherein it is connected to the chamber wall by a conical interference fit. The mixing chamber can be partially or completely filled with flushing liquid, e.g. from a reagent reservoir, via a channel  42 , as a result of which the sample is released from the sample carrier and diluted. Here, the flow cell is preferably located in a vertical position, such that the level of the liquid in the mixing chamber can be monitored through a transparent cover film  43  and/or air located in the mixing chamber can escape during the mixing process. For the release of the sample, it is advantageous to agitate the flushing liquid, i.e. pump it back and forth. The diluted sample can be transported through the channel  42 , or another channel connected to the mixing chamber, for further analysis or processing within the flow cell. The flow cell and the sample carrier can have structures, e.g. snap-fit fasteners, undercuts or latching lugs, which latch into place upon connection of the sample carrier to the flow cell and which prevent removal of the sample carrier after the connection to the flow cell. 
     A sample carrier corresponding to the sample carrier from  FIG. 5 a    is connected, according to  FIG. 10 b   , to a chamber  44  which is arranged near but outside a center of rotation of the flow cell. In the flow cell, the transport of fluid takes place partially or completely by centrifugation. For further analysis, the sample is also transported by centrifugal force almost completely into a channel  44   a  attached to the transport chamber  44 . An undiluted liquid sample can be transported away in the manner described. 
     According to  FIG. 10 c   , a sample-receiving region of a sample carrier protrudes with a conical support element into a transport channel  45  of a flow cell. The end of the conical sample carrier extends as far as a cover film  46  of the flow cell. In the example shown, the sample carrier and the flow cells have an alignment element  47  and  48 , respectively, in order to ensure that a groove-shaped sample-receiving region is aligned with the transport channel  45 . From the sample-receiving region, the sample can be transported pneumatically or hydraulically in the transport channel  45  of the flow cell to further processing devices. 
     In an illustrative embodiment shown in  FIG. 10 d   , alignment structures, e.g. a slot  49  or the like, are provided to indicate that a sample carrier is aligned with a groove-shaped sample-receiving region transversely to the longitudinal direction of a transport channel. Despite an interference fit, a sample carrier is still rotatable and can be transferred from such a position to the position shown in  FIG. 5 d    where, according to the example of  FIG. 10 c   , the sample-receiving region can be emptied. 
       FIG. 11  shows a connection of the sample carrier of  FIG. 5  to a flow cell. The flushing channel  30  of the sample carrier is connected to a channel  50  of the flow cell, through which channel  50 , according to arrow  51 , compressed air or flushing liquid is supplied which forces the sample quantity  32  into a further channel  52  of the flow cell. 
       FIG. 12  shows an example for a connection of the sample carrier of  FIG. 9  to a flow cell. By way of channels  53  to  55  of the flow cell, the stored sample quantity is flushed out in a manner that avoids an air cushion, as is described with reference to  FIG. 9 . 
     Plastics generally have hydrophobic surfaces that are difficult to wet with aqueous fluids such as blood. Hydrophilic surfaces are advantageous for the sample-receiving region of sample carriers, also with a view to an exact measurement of sample quantities. 
     Changes (hydrophilic or hydrophobic) to the surface properties of plastics occur, as is known from wet chemistry, by application of wetting agents or surfactants and subsequent drying, by surface activation by means of plasma, flame treatment or corona treatment (hydrophilic), by surface coating by means of plasma polymerization, e.g. formation of glass-like layers (hydrophilic or hydrophobic), or by combinations of these measures. If appropriate, local masking of treated surfaces takes place. 
       FIG. 13 a    shows a sample carrier whose sample-receiving region  57  and whose conical sealing region is hydrophilically coated, e.g. with a glass-like layer. The contact angle to water is &lt;50°. When sample material is dropped on in a quantity that is greater than the sample quantity to be metered, the sample quantity to be metered, e.g. 10 mm 3 , remains in the receiving region, while excess sample material, e.g. 30 to 40 mm 3 , of a drop of blood runs down the conical support element and collects in the lower region of the sample carrier. By suitable retention structures, it is possible to prevent the collected sample material from entering a flow cell. In a departure from the example shown, the entire surface of the sample carrier could also be hydrophilized. 
     In the illustrative embodiment in  FIG. 13 b   , a surface treatment is confined to a groove-like receiving region  58 , which can be hydrophilically modified, for example by wet chemical treatment or masked plasma coating. In this illustrative embodiment, the sample is preferably taken up by dipping the sample carrier into a sample droplet, e.g. blood on a finger pad. The quantity of the sample taken up is defined by the geometry of the hydrophilically modified sample-receiving region. In the adjacent regions with a hydrophobic surface, the sample scarcely adheres or does not adhere at all. 
     The illustrative embodiment in  FIG. 13 c    corresponds to the preceding illustrative embodiment but has in addition a hydrophobic coating  60  outside the sample-receiving region  59 . The typical contact angle is &gt;90°, in order to further increase the contrast in wettability between receiving region and adjoining region and thus more precisely measure out sample quantities. 
       FIG. 13 d    shows an illustrative embodiment for a sample carrier consisting of two differently wettable plastics. A core part  56  of a conical support element has a contact angle of &lt;70°, e.g. PMMA, while an outer region of the conical support element, for example made of olefin plastic such as PP, has a contact angle of &gt;90°. The geometry of the core part  56  is cylindrical. The combination of materials is chosen such that the two materials (e.g. PP and PMMA, PP and POM) are not connected rigidly but instead movably in the two-component injection molding procedure. By means of this “assembly-type injection molding”, in which the inner core remains movable, it is possible to form a sample-receiving region that can be emptied by displacement of the inner core. 
     In the illustrative embodiment of  FIG. 13 e   , compared to the illustrative embodiment of  FIG. 13 b   , a groove-shaped sample-receiving region is formed which is closed on one side with a film  61 , but is open at the ends. The inner walls of this channel-shaped receiving region can be coated hydrophilically, e.g. by wet chemistry or by means of plasma treatment. 
     In the illustrative embodiment of  FIG. 13 f   , a sample-receiving region is partially or completely coated with a dry reagent  62  and functionalized. In this way, a sample can be conditioned immediately after being taken up by the sample carrier, before a connection of the sample carrier to a flow cell or other processing device takes place. For example, an anticoagulation reagent can be applied which, for example, prevents clotting of a quantity of blood on the sample carrier, for which purpose materials such as heparin or citrate may be considered. The dry reagent can also be a lysis buffer for lysis of cells, e.g. of a blood sample. 
     While  FIG. 14 a    again shows a sample carrier with, as in the preceding illustrative embodiments, a handling region surrounding the conical support element in a pot shape, the illustrative embodiment in  FIG. 14 b    has a sample carrier with a conical handle  64  and a receiving region  63 . 
     In the illustrative embodiment in  FIG. 14 c   , a conical handle part  65  can be broken off at a predetermined breaking point  66  after connection of the sample carrier, e.g. to a flow cell. 
       FIG. 14 d    shows a sample carrier with an indentation  67 , into which it is possible to insert a handling pin  68  which is releasable after connection of the sample carrier, e.g. to a flow cell. 
     A further sample carrier for pre-processing a blood sample is shown in  FIG. 15 . 
     In the sample carrier of  FIG. 15 , a conically widening sample-receiving space  79  is formed in a first plastic injection-molded part  81 , said sample-receiving space  79  being delimited by a plasma separation membrane  80  which initially stops the capillary filling of the sample-receiving space  79  with a blood sample. A second conical injection-molded part  82 , adhesively bonded or welded to the first injection-molded part  81 , has a passage  83  that can be filled by capillary action. Both the sample-receiving space  79  and the passage  73  are provided with a hydrophilic coating on the inside. The sample carrier can be connected to a flow cell via the conical injection-molded part  82 . 
     After a blood sample has been introduced into the receiving space  79 , plasma passes through the plasma separation membrane  80  into the passage  83 , the open end of the latter forming a capillary stop for metering the plasma sample. 
     When the sample carrier is plugged onto a flow cell, the first injection-molded part  81  can serve as a grip element, wherein a cap is expediently used if necessary in order to prevent contamination of the environment by blood that remains in the receiving space  79 . The blood plasma to be analyzed by the flow cell can be sucked out of the passage with the aid of a nonwoven or of a membrane that adjoins the opening of the passage  83 . 
       FIG. 16  shows a sample carrier produced in one piece as a plastic injection-molded part and having a passage  86  with a constriction  85 . Except for the constriction  85 , the passage  86  forms a sample-receiving capillary  84 . The passage  86  extends through a conical element and through a grip part integrally connected to the conical element. An annular shoulder  87  is formed between the grip part and the conical element. When a sample is received in the sample-receiving capillary  84 , the rest of the passage  86  forms a venting channel. When the sample carrier is connected to a flow cell, the passage  86  can moreover form a flushing channel for flushing the sample out into the flow cell. 
       FIG. 17  shows the sample carrier from  FIG. 16  in conjunction with a pin-like handling appliance  88  which can be placed with one end onto the annular shoulder  87  and can be placed with a conical inner wall  93  onto a conical end of the sample carrier and can serve to plug the sample carrier onto a flow cell. In the manner of a ballpoint pen refill, the handling appliance has a core element  89  which is movable in the axial direction and whose movement according to  FIG. 17 c    permits release of the handling appliance  88  from the sample carrier plugged onto the flow cell. 
     As can be seen from  FIG. 18 , the core element  89  can also have a clamping projection  92  for engagement in the passage  86  of the sample carrier. The clamping is provided in such a way that venting of the sample channel is not thereby disturbed. To release the clamping, the outer part of the handling appliance  88  is advanced, according to  FIG. 18 b   , relative to the core element  89  under pressure against the annular shoulder  87 . 
       FIG. 19  indicates that the sample carrier could also have a sample-receiving region  90  in the manner of a groove or recess, as is described above in connection, for example, with the sample carrier  7  from  FIG. 4 . The core element  89  of the handling appliance  88  could then engage with a clamping action in a longitudinal channel  91  of the sample carrier. 
       FIG. 20  shows a dosing element with a conical plug attachment  94 , via which it can be plugged onto a flow cell shown in  FIG. 21 . The plug attachment  94  has a groove channel  95  in an end wall at the free end and is connected to a rotary handle  96  comprising two wings, each of them with an abutment  97 ,  98 , respectively, on the wings. 
     The flow cell shown in  FIG. 21  has a conical plug opening  99  for receiving the plug attachment  94 . A sample can be introduced into the flow cell via an input port  100 , e.g. with the aid of a pipette or syringe. The input port  100  is connected via a channel  101  and the plug opening  99  to an overflow port  102 . The flow cell consists of a plate  103  and of a film  104  which is adhesively bonded or welded to the plate and which covers the channel  101 . 
     The flow cell moreover has flush ports  105  and  106 , which are connected to each other via a channel  107 . Abutments  108  and  109  are formed on the plate  103 , on the side directed away from the channels  101 ,  107 . 
     In order to measure a sample, the dosing element is inserted, with the plug attachment  94  to the front, into the plug opening  99  of the flow cell, wherein the groove channel  95  is covered by the film  104 . The dosing element is located in the rotation position shown in  FIG. 22 a   , in which the wings of the rotary handle  96  bear against the abutments  108  and  109 . In this position, according to  FIG. 22 b   , the groove channel  95  of the conical plug attachment  94  supplements the channel  101  between the input port  100  and the overflow port  102 . A sample material introduced into the input port  100  can flow across into the overflow port  102 . 
     In order to dose a defined sample quantity, the dosing element is rotated through 90° and, according to  FIG. 22 c   , bears with its abutments  97  and  98  against the input port  100  and overflow port  102 , respectively ( FIG. 22 c   ). In this position, the openings of the ports are sealed by the wings of the rotary handle  96 . By means of the rotation, a sample quantity is measured off which corresponds to the inner volume of the groove channel  95 . In this position, the groove channel  95  supplements the channel  107  between the flushing ports  105 ,  106 . 
     The dosed quantity of a sample contained in the groove channel  95  can therefore be flushed out of the flow cell via the flush ports  105  and  106  and delivered for further processing.