Abstract:
The invention concerns a test system comprising a test device which has a lancing drive and an optical measuring device, and at least one test unit that is inserted into the test device as a disposable article, preferably in a magazine. According to the invention it is proposed that the measuring device can be directly coupled to a detection element of the test unit by means of an optics adapter on the device side, where a free end of the spring-loaded optics adapter lies against the detection element in a force-locking manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/EP2010/056306, filed May 9, 2010, which claims the benefit and priority of European Patent Application No. 09159834.2, filed May 9, 2009. The entire disclosures of the above applications are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The invention concerns a test unit for use in a test device for a single-use analysis of a body fluid consisting of a lancing element that can be inserted into the skin of a user and an analytical detection element that can be loaded with body fluid from the skin, which consists of a reagent layer which reacts with an analyte in the body fluid and a transparent carrier platelet coated with the reagent layer. The invention additionally concerns a test system for the corresponding processing of such test units. 
         [0003]    Such a test system is described in International Application Publication No. WO 2007/045412, Haar et al., published Apr. 26, 2007 (see also, U.S. Patent Application Publication No. 2008/0249435, Haar et al., published Oct. 9, 2008) of the applicant in which the disposable test units are provided with non-displaceably integrated light guides in order to guide the measuring light from a measuring zone to a shaft end of a lancing component onto which a coupling part is additionally injection-moulded for mechanical coupling. In one embodiment it is proposed in this document that the optical coupling can take place at the rear side of the test field across a carrier foil which is permanently joined to the distal ends of the integrated light guides. Such an arrangement avoids a laborious sample transport due to the fact that the measurement is carried out directly in the collecting zone but at the same time results in an increased complexity of the test units that can only be used for a single measurement. 
       SUMMARY 
       [0004]    Based on this, the object of the invention is to further improve the known units and systems in the prior art and in particular to specify a favourable design also for the mass production of miniaturized disposable parts with at the same time a reliable measurement value detection. 
         [0005]    In various embodiments, the present technology provides a test unit for use in a test device for a single-use analysis of a body fluid consisting of a lancing element that can be inserted into the skin of a user and an analytical detection element that can be loaded with body fluid from the skin, which detection element consists of a reagent layer which reacts with an analyte in the body fluid and a transparent carrier plate coated with the reagent layer, wherein the detection element is attached rigidly to the lancing element and can be loaded with body fluid via a capillary channel of the lancing element, characterized in that the carrier plate forms an optical interface for photometric measurement value detection at a connecting face facing away from the reagent layer that can be brought into direct abutment with an optics adapter of the device. 
         [0006]    The invention is based on the idea of keeping the test unit free of optical waveguides and instead to dock on a light guide structure provided in the device preferably in a force-fitting manner. Accordingly it is proposed according to the invention that the carrier plate that is preferably formed from a foil as a transparent piece of flat material forms an optical interface for photometric measurement value detection at a connecting face facing away from the reagent layer that can be brought into direct abutment with an optics adapter which is installed as a component of the test device by being pressed against it. Thus, an additional light guide structure in the disposable part is dispensed with as a result of which particular advantages are achieved with regard to the overall size which is also of importance for storing a large number of consumable units in a magazine, in addition to the reduced production costs. In this connection it should also be borne in mind that several parallel light guides may be necessary for a reliable measurement value detection which would considerably increase the dimensions. In addition no coupling between light guides on the device side and consumable side would be necessary which saves an additional lossy interface. 
         [0007]    In order to obtain an optimal measurement signal, it was recognized as particularly important that the thickness of the carrier plate should be matched to the optical properties of the light guides in the optics adapter and in particular to their diameter, numerical aperture and distance from one another. The refractive index of the carrier plate also has to be taken into consideration. In addition it should be possible to use commercial foils as a starting material. Taking these boundary conditions into account, it is particularly advantageous when the carrier plate has a thickness of less than 500 micrometers, preferably about 200 to 300 micrometers. 
         [0008]    For the targeted processing of very small amounts of samples taking into consideration that they are provided in a capillary-active manner, it is additionally advantageous when the carrier plate is formed as a blank from a foil and preferably has a broadside area of less than 5 mm 2 , preferably less than 1 mm 2 . 
         [0009]    Both aspects of the opto-mechanical coupling can be taken into account in a particularly advantageous manner by means of the fact that the lancing element has a counter bearing for supporting a force-fitting connection between the optical interface and the optics adapter. 
         [0010]    For a rapid and accurate lancing movement it is advantageous when the lancing element has a coupling structure that can be brought into engagement with a lancing drive of the device. Another improvement in this regard results from the fact that the lancing element has two elastic coupling arms which can be deflected in opposite directions at right angles to a lancing axis where the coupling arms can be brought out of a pre-tensioned release position into an untensioned coupling position during the lancing movement of the lancing element. 
         [0011]    With regard to the manufacturing process, it is particularly advantageous when the lancing element is formed in one piece from sheet material as a flat formed part and is in particular etched so that no additional functional parts have to be shaped on it. It is also of particular advantage when the detection element is attached rigidly to the lancing element and can be loaded with body fluid via a capillary channel. 
         [0012]    A configuration that is particularly advantageous also for the device coupling is created by means of the fact that the lancing element has a base part with a U-shaped contour and a needle-shaped lancing member preferably provided with a capillary channel that is moulded onto the base part. 
         [0013]    Another aspect of the invention consists of a test system comprising a test device and at least one test unit used therein as a disposable article, wherein the measuring device can be directly coupled to the detection element of the test unit by means of an optics adapter on the device side and a free end of the preferably spring-loaded optics adapter lies in a force-locking manner against a carrier plate of the detection element in the form of a transparent piece of foil or flat material. The force lock allows compensation for manufacturing tolerances and at the same time measurement signals can be reliably picked up even during the lancing movement. 
         [0014]    An advantageous embodiment provides in this connection that the optics adapter is supported by a return means preferably in the form of a spring and can be pressed against the detection element under a force exerted by the return means. 
         [0015]    Another improvement is achieved in that the optics adapter is movably mounted in a drive rod of the lancing drive and that the drive rod can be coupled to the test unit preferably by means of grippers in a tension-resistant manner. 
         [0016]    In order to firstly enable a defined mechanical coupling it is advantageous when a spring force acting in the advance direction can be applied to the optics adapter in the course of an advance movement generated by the lancing drive by means of a control unit switched in a travel-dependent manner, for the optical coupling to the detection element. 
         [0017]    In order to directly pick up a signal on the analytical component, it is advantageous when the optics adapter has one or more light guides running side by side and when the end faces of the light guides can be connected in a butt joint to the connecting face of the carrier plate. 
         [0018]    For a reliable measurement value detection it is advantageous when a connecting end of the optics adapter facing away from the test unit is connected in a non-displaceable manner to an opto-electronic component assembly of the measuring device. 
         [0019]    The test unit is advantageously supported in a guide preferably in a magazine chamber, wherein the guide has an in particular arched guide track to make a form-fit between the test unit and the lancing drive in the course of a lancing movement so that an automatic mechanical coupling is achieved. 
     
    
     
       DRAWINGS 
         [0020]    The invention is further elucidated in the following on the basis of the embodiment examples shown schematically in the drawing. 
           [0021]      FIG. 1  shows a blood sugar test system with a magazine for test units shown partially cut open that is used therein in a perspective view; 
           [0022]      FIG. 2  shows the test system according to  FIG. 1  with an activated test unit in a diagram without the magazine; 
           [0023]      FIG. 3  shows a test unit according to  FIG. 2  mechanically coupled to a lancing drive; 
           [0024]      FIGS. 4 and 5  show a sectional side view and underside view of the arrangement according to  FIG. 3 ; 
           [0025]      FIGS. 6 to 8  show the additionally optically coupled test unit in the advanced lancing position according to the diagrams according to  FIGS. 3 to 5 ; 
           [0026]      FIG. 9  shows an isolated test unit in a perspective view; 
           [0027]      FIG. 10  shows the magazine according to  FIG. 1  in a sectional top view; and 
           [0028]      FIG. 11  shows the optical path for an optics adapter coupled to the test unit in a diagrammatic illustration. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    The following description of technology is merely exemplary in nature of the subject matter, manufacture and use of one or more inventions, and is not intended to limit the scope, application, or uses of any specific invention claimed in this application or in such other applications as may be filed claiming priority to this application, or patents issuing therefrom. 
         [0030]    The test system  10  for blood sugar measurement shown in the drawing comprises a compact portable test device  12  with an incorporated lancing drive  14  and measuring device  16  as well as an exchangeable disk-shaped magazine  18  with a plurality of test units  20  located therein as consumable articles for carrying out in each case one blood sugar test, where the test units  20  in a particularly simple construction consist of a lancing element  22  with an integrated detection element  24  for sample collection and direct photometric measurement value detection. In this connection the detection element  24  is fixed in a stationary position on the lancing element  22  and thus it can be moved with the lancing element  22  during a lancing movement. 
         [0031]    This allows even laymen to self-determine the blood sugar concentration in a fully automatic measuring process in a reliable manner with a high degree of handling convenience. 
         [0032]    As illustrated in  FIG. 1  rotating the magazine  18  allows a plurality of test units  20  in respective magazine chambers  26  to be brought successively into an active usage position with respect to a support  28  provided with a puncturing opening for positioning the finger of a user. The lancing drive  14  engaging into the actively positioned magazine chamber  26  then enables the test unit  20  to be moved back and forth along a lancing axis  30  as shown in  FIG. 2 . After blood collection and measurement value detection are completed, the used test unit  20  can be retracted again into the magazine chamber  26  and thus disposed of. 
         [0033]    In general such measurements can, apart from on the finger pad, also be carried out on other parts of the body for example in the less pain-sensitive arm or stomach region where in addition to capillary blood, tissue fluid or mixtures thereof are also suitable for sample collection from the skin. 
         [0034]      FIG. 9  shows a single test unit  20  consisting of a lancing element  22  and detection element  24 . The lancing element  22  is etched in one piece from a high-grade steel sheet as a flat, shaped part and has a U-shaped base part  32  and a lancing member  34  shaped centrally and distally thereon, which is provided with a channel-shaped capillary channel  36  for blood collection during the skin puncture. The proximally projecting U-arms form coupling arms  38  which can be deflected in opposite directions at right angles to the lancing axis  30  as is elucidated in more detail in the following. A coupling structure  40  for hooking the lancing drive  14  is formed on the free ends of the coupling arms  38  where the eyes  42  form a counter bearing to support it against a spring pressure force introduced in the distal direction during the optical coupling. 
         [0035]    As can be seen additionally in  FIG. 9 , the detection element  24  consists of a small flat carrier plate  44  which is firmly inserted into the lancing element  22  and is provided with a reagent layer  46  on its side facing the channel  36 . This layer reacts irreversibly as a known enzymatic system to an analyte (glucose) in the blood fluid that flows against it by a change in colour that can be reflectometrically detected on the rear side through the small transparent carrier plate  44 . The carrier plate  44  consisting of a transparent material with its rear side connecting face facing away from the reagent layer  46  thus forms, an optical interface for direct coupling on the device side without requiring additional light guides or optical structural components in the consumable. The carrier plate advantageously consists of a foil blank for example made of PET, PC or PMMA. 
         [0036]      FIG. 10  shows a section of two magazine chambers  26  where only the left chamber is loaded with a test unit  20 . Its coupling arms  38  are held in a pretensioned starting position for mechanical coupling to the lancing drive  14 . For this purpose the magazine  18  has guide tracks  50 ,  50 ′ on the cover and bottom which in a proximal end section diverge in an arch shape and thus cause the coupling arms  38  to spread correspondingly. During the radial advance in the direction of the distal guide track end  52 , the coupling arms  38  swing into a common guide plane in which the eyes  42  automatically hook into the lancing drive  14  while the pretensioning is released so that a substantially frictionless lancing process is possible. 
         [0037]      FIGS. 3 to 5  show this coupling position of the test unit  20  in a starting phase in which there is not yet any optical connection to the detection element  24 . Here the gripper end  56  of a drive rod  54  of the lancing drive  14  is hooked into the eyes  42  of the test unit  20  with end play where the lancing member  34  is still located in the magazine chamber  26 . The drive rod  54  is attached to a carriage  58  which can be placed onto a rail  62  in the housing dome  64  which is fixed in position in the device on a guide groove  60  that is open at the bottom and can be moved backwards and forwards thereon by means of a drive pin  66  in order to transfer the lancing movement. In this case the drive pin  66  is guided in a connecting link disk that is not shown which mediates a desired lancing profile under a motor-driven rotation. 
         [0038]    As can be seen in particular in  FIG. 2  an optics adapter  68  on the device side designed as part of the test device enables a direct optical coupling of the measuring device  16  to the detection element  24  of the test unit  20 . The optics adapter  68  is mounted with limited movability in the drive rod  54  in the form of an inner rod. The optics adapter  68  is rigidly connected to an opto-electronic component assembly  72  at its T-shaped connecting end  70  that faces away from the test unit  20 . This component assembly  72  contains a light emitter and light detector as part of the measuring device  16  so that a robust electrical output signal can be provided for further processing. Several light guides  74  run side by side in the optics adapter  68  for direct optical coupling to the detection element  24 . These light guides end at a free distal end face  76  which can be connected in a butt joint to the connecting face  48  of the detection element  24  which is initially at a distance therefrom. 
         [0039]    In order to be able to reliably make an optical connection by means of a force lock, a swan-neck-shaped leaf spring  78  is provided as a return means, the one spring end  78 ′ of which is attached to the carriage  58  and the other spring end  78 ″ of which presses against the lower arm of the T-shaped connecting end  70  of the optics adapter  68  ( FIG. 3 ). 
         [0040]    The pretensioning of the spring  78  is only applied during the advance movement after the gripper end  56  has hooked onto the optics adapter  68 . For this purpose a control lever  80  is mounted pivotably as a control means on the carriage  58 . As can be seen in  FIG. 5  the control lever  80  sweeps a stepped control track  82  which runs next to the rail  62  during the lancing advance. In the starting area of control track  82  the connecting end  70  is supported by the control lever  80  so that the spring  78  does not advance the optics adapter  68 . 
         [0041]    As shown in  FIGS. 6 to 8  the optics adapter  68  makes a form-locking connection with the detection element  24  as soon as the control lever  80  has swept across the step of the control track  80  during the advance. The end face  76  is then pressed from the rear side against the detection element under the pretensioning force of the spring  78  in order to enable a direct coupling-in or -out of the measurement light. The gripper end  56  is thus brought into a tension-resistant connection with the elongated holes or eyes  42  which absorb the reaction force of the spring advance and thus act as counter bearings. In this manner the lancing movement can take place in the tensioned state during which a microscopic amount of blood is taken up in the skin puncture and is analyzed once. 
         [0042]      FIG. 11  shows the optical path for the measurement in a simplified diagram. The light of two light-emitting diodes LEDs optionally having different wavelengths is beamed centrally behind the channel  36  via associated light guides  74 . For a more accurate point alignment, the light guides  74  can converge towards the free end  76  in such a manner that their mutual distance from one another is less than on the radiation side. The measurement light scattered on the reagent layer  46  is also passed back onto a photodiode PD as a detector via an associated central light guide  74 . In order to obtain the largest possible wanted signal and in doing so ensure a low dependency on distance tolerances, the thickness of the carrier foil  44  is limited to about 200 to 300 micrometers. At the same time the connecting face can be limited to about 0.6×0.6 mm 2  such that even the smallest filling amounts in the capillary channel  36  result in an adequate wetting of the reagent layer  46 . 
         [0043]    The described system  10  enables a complex measuring process to be achieved with reduced mechanical and optical components on the side of the consumable part  20  that is processed as a unit. The user only has to carry out one handling step for sample collection and measurement and does not have to be concerned about disposal of the consumable parts. The spring coupling of the optics adapter  68  in the direction of the lancing axis  30  enables tolerances to be compensated without signal losses occurring.