Abstract:
A device for analyzing body fluids comprising a lancing element that can puncture a body part along a lancing axis. The lancing element has a collection volume for collecting body fluid obtained by a puncture and a receiving element that can be loaded with body fluid from the collection volume and that can detect a component of the body fluid. The lancing element and the receiving element are arranged in the lancing axis so that they can be moved relative to one another such that the receiving element dips into the collection volume in the lancing direction during a transfer phase following the puncture.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation application of International Application PCT/EP2007/063130, filed Dec. 3, 2007, which claims priority to EP 06025269.9, filed Dec. 7, 2006, which are hereby incorporated by reference in their entirety. 
     
    
     BACKGROUND 
       [0002]    The invention concerns a device for analyzing body fluids, especially for blood sugar tests, comprising a lancing element that can puncture a body part along a lancing axis. The lancing element has a collection volume for collecting body fluid obtained by a puncture, and a receiving element that can be loaded with body fluid from the collection volume. The receiving element can detect a component of the body fluid. The invention additionally concerns a corresponding analytical method and a method for sterilizing such a device designed as a disposable part. 
         [0003]    A test element for examining body fluids for analytical purposes and especially for determining the blood glucose concentration is described in an earlier application WO 2008/068215 A2 of the applicant. This application teaches a lancing element with a collection area for body fluid where the collection area is formed by a collecting opening which is elongated in the direction of lancing and a permanently integrated light guide, the distal end of which is located in a proximal measuring zone of the collecting opening. This allows an optical detection of an analyte to be carried out by means of a microfluidic liquid transfer within a lancing structure. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention further develops the systems known in the prior art and optimizes a device and a method of the type stated above by providing reliable sample processing where the aim is for the smallest possible amounts of sample, reducing the lancing pain, and also simplifying production. 
         [0005]    Embodiments incorporating the invention are based on the idea of avoiding an excess volume for a capillary sample transport and instead bringing the receiving element into direct contact with the sample by a suitable relative movement. Accordingly, the lancing element and the receiving element can be arranged in or along the lancing axis so that they can be moved relative to one another. The receiving element can be arranged in an initial position outside the collection volume of the lancing element such that the receiving element does not come into body contact during the puncture and such that the receiving element extends or dips into the collection volume in the lancing direction during a transfer phase following the puncture. As a result, the receiving element engages in the collection volume in a receiving position. This allows the receiving element to be adequately wetted with liquid even without capillary transport of the liquid, and malfunctions are avoided to a large extent by the directed immersion. Hence, it is possible to carry out a complete measurement process to a large extent automatically with very small amounts of samples in a miniaturized design. In this connection, the receiving element can either merely mediate a further sample transport or act directly as a sensory element. 
         [0006]    In one embodiment, the distance between the lancing member of the lancing element and the receiving element is smaller in the transfer phase than in a prior lancing phase. Hence, body contact of the receiving element is avoided in the lancing phase while the amount of sample can be correspondingly reduced by the reduction in distance. 
         [0007]    The receiving element can be advantageously inserted into the collection volume by a retracting movement of a lancing drive coupled with the lancing element. Alternatively, it is also possible that the receiving element can be moved into the collection volume by means of a feed drive. 
         [0008]    In order to be able to utilize drive units that are permanently mounted in the device, it is advantageous when the lancing element and/or the receiving element have a docking structure for a detachable drive coupling at one proximal end. 
         [0009]    It is advantageous for a simplified measurement process when the lancing element is mounted in a linear guide that can be formed by an associated case. 
         [0010]    A constructionally advantageous embodiment provides that the receiving element engages in a recess of the lancing element leading to the collection volume. 
         [0011]    The lancing element and the receiving element can be advantageously designed to belong together as a disposable part. This allows measurements to be carried out with great user convenience. A further improvement in this regard can be achieved by a magazine and in particular a disk, drum or stack magazine designed to receive a plurality of lancing elements and associated receiving elements. 
         [0012]    In order to further increase the measurement integration it is advantageous when the receiving element has a measuring member for an optical or electrochemical measurement in the collected body fluid. In this connection it is preferred that the measuring member is coated with a test reagent that reacts with the component of the body fluid while under liquid contact. 
         [0013]    For signal transmission to an instrument unit it is advantageous when the receiving element can be connected or is connected to a measuring unit via a light guide routed in the lancing element. 
         [0014]    For an optimized uptake of liquid, it is advantageous when the collection volume is formed by a slot that is open on both sides or a channel of the lancing element that is open on one side. 
         [0015]    Another aspect of the invention is that the collection volume may receive or require less than 50 nl, preferably less than 10 nl body fluid. In this manner it is possible to further reduce the pain during sample collection and thus increase user acceptance. Due to the special sample collection, it is sufficient when an aliquot of the body fluid is applied from the collection volume onto a distal front side of the receiving element where the aliquot can be less than 5 nl and preferably less than 1 nl. 
         [0016]    The invention also concerns a lancing apparatus for use of at least one device in the form of a disposable part comprising a lancing drive that can be triggered by a user where, in the unused state, the disposable part is mounted in a first position inside the apparatus and after the puncture it is stored in a used state in a second position at a distance thereto inside the apparatus. Hence, this ensures that they are provided and disposed of without user manipulation. 
         [0017]    In a process according to the invention the receiving element are moved in the lancing axis relative to one another during a transfer phase that follows the puncture such that the receiving element dips into the collection volume in the direction of lancing. This also results in the advantages that have already been elucidated above. 
         [0018]    In an advantageous embodiment the distance between the receiving element and a distal lancing member of the lancing element is reduced in the transfer phase and the receiving element is moved together with the lancing element during the puncture or the lancing element is driven in a reciprocating lancing movement while the receiving element is held stationary. 
         [0019]    The lancing element is advantageously located outside the body part containing the body fluid in the transfer phase and it is of further advantage when an optical or electrochemical measurement is carried out in the collected body fluid by means of the receiving element as a measuring member. 
         [0020]    A further aspect of the invention is a method for sterilizing a device according to the invention designed as a disposable part in which the receiving element coated with a test reagent is kept at a distance from a distal lancing member of the lancing element and the lancing member is preferably irradiated with an electron beam. In this connection, it is possible that the radiation and in particular the electron beam is focused on the lancing member and/or the distance between the receiving element and the lancing member is selected such that the test reagent is not damaged by the radiation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0021]    The above-mentioned aspects of the present invention and the manner of obtaining them will become more apparent and the invention itself will be better understood by reference to the following description of the embodiments of the invention, taken in conjunction with the accompanying drawings, wherein: 
           [0022]      FIG. 1   a  is a diagrammatic view of a device for blood sugar measurement with a disposable lancing and detection element; 
           [0023]      FIGS. 1   b  and  c  show the lancing and detection element of  FIG. 1   a  in a lancing and detection position; 
           [0024]      FIGS. 2   a - 2   c  show a disk magazine with an active lancing and detection element in various positions in a top-view; 
           [0025]      FIGS. 3   a - 3   b  show a further embodiment of a lancing and detection element in two positions in a perspective views; and 
           [0026]      FIGS. 4   a - 4   e  show yet a further embodiment of a lancing and detection element in various positions in axial section views. 
       
    
    
     DETAILED DESCRIPTION  
       [0027]    The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention. 
         [0028]    The diagnostic measuring arrangement shown in  FIG. 1  comprises an analyzer  10  for blood sugar measurements and at least one test element  12  that can be inserted therein as a consumable for single use and which has a lancing element  14  and a receiving or detection element  16 . 
         [0029]    As shown in  FIG. 1   a , the analyzer  10  has a device housing  18  with a support  20 , for example, for a finger  22  (a portion of which is shown) in the area of a piercing opening  24 . The lancing element  14  is mounted within the housing  18  in a linear guide  26  in order to execute a reciprocating lancing movement against the applied finger  22 . For this purpose the lancing element  14  can be detachably connected to the pusher  30  of a lancing drive  32  via a proximal docking structure  28 . A detection unit  34  which can be coupled via a flexible lead  36  to a light guide  38  of the detection element  16  is provided inside the device for an optical glucose detection in a blood sample obtained by means of the lancing element  14 . 
         [0030]    The lancing element  14  is formed as a flat part, for example, from a stainless steel sheet and has a distal tip  40  as a lancing member in the rear area of which there is a collection volume  44  delimited by a slot  42  that is open on both sides. 
         [0031]    The light guide of the detection element  16  engages in the slot  42 , and a front face or receiving element of the light guide  38  coated with a test reagent  46  is aligned head-on to the collection volume  44 . The test reagent  46  changes color when blood fluid is applied to it due to the glucose that is contained therein so that it is possible on the basis of the color change to carry out an optical detection by means of the detection unit  34  via the light guides  38 ,  36 . The measuring result can be displayed to the user in order to enable an on the spot self-examination. 
         [0032]    As shown in  FIGS. 1   a, b , and  c , the lancing element  14  is arranged in the guide  26  such that it can be substantially moved linearly relative to the detection element  16  that is held in a fixed position in the device. Hence, the lancing element  14  can be moved backwards and forwards along a lancing axis  48  so that the body part  22  can be punctured and the blood sample obtained in this process can be transferred onto the test reagent  46 . In the initial position of FIG. la the lancing movement can be triggered by the user after applying the finger  22 . In the subsequent lancing phase, the lancing member  40  penetrates into a blood-yielding skin layer  50  when the lancing depth has been suitably adjusted. During the retraction movement which generally takes place more slowly than the rapid forwards movement during the puncture, body fluid  52  (blood or also tissue fluid) is taken up in the collection volume  44 . A microscopic amount of blood in the range of 10 nanoliters or less is sufficient in this case. In the final transfer phase, a portion of the collected body fluid  52  is transferred onto the detection element  16  by the return movement of the lancing element  14  and the reagent layer  46  as a sensory element dips proximally into the collection volume  44 . Due to the reduction in the distance between the sensor element (test reagent  46 ) and the lancing member  40  or the collection volume  44 , it is thus not necessary to take up any excess liquid volume for a capillary transport of the body fluid. An extremely small partial volume of about 1 nanoliter is sufficient for the actual detection reaction at the tip of the light guide. 
         [0033]      FIGS. 2   a - 2   c  illustrate a possible use of a large number of test elements  12  in a disk magazine  54 . The test elements can be sequentially brought into an active position (test element  12 ′) by rotating such a disk magazine  54  in a device  10 . According to  FIG. 2   b  the puncture then takes place while increasing the distance between the lancing member  40  and the detection element  16  whereas in the transfer phase according to  FIG. 2   c  liquid is transferred by reducing the distance. The used test element is subsequently disposed of by advancing the magazine  54 . 
         [0034]      FIGS. 3   a  and  3   b  show an embodiment of a test element  12  in an accompanying cylindrical case  56  which forms a part of the disposable article and together with a central recess  58  forms a guide  26  for the U-shaped longitudinally slotted lancing element  14 . A light conducting rod  38  arranged in the slot  42  of the lancing element  14  is also permanently connected to the case  56  as a part of the consumable article. The front wall of the light conducting rod  38  is coated with the test reagent  46  and the rear side can be docked to the light guide  36  which is coupled on the instrument side to the detection unit  34 . For this purpose a gripper-like claw clutch  60  is provided on the lancing element  14  as a docking structure  28  which automatically engages in a form-fitting manner with the head piece  62  of the drive pusher  30  during the advance movement (arrow  64 ). For this purpose run-on slopes  66  are formed on the inside of the case  60  which close the elastically spreading claws  60  so that it is possible to execute a return movement after blood collection. In this embodiment it is possible that the case  56  is moved up to the finger  22  by a separate advancing drive and in doing so the free front end presses against the skin as a reference surface for the lancing depth and stabilizes the skin. 
         [0035]    In the embodiment shown in  FIGS. 4   a - 4   e,  the same parts are also provided with the same reference numerals as described above. In the initial position of  FIG. 4   a  the front opening of the case  56  is closed in a sterile manner by a sealing cover  70 . The test reagent  46  thus remains also protected against environmental influences and in particular against moisture. The case  56 , the lancing element  14  and the detection element  16  are each provided at their proximal end with a docking structure  72 ,  28 ,  74  for a separate drive coupling. In the sequence of operations that are shown, the sealing cover  70  is first opened by advancing the entire disposable part  76  and the front end makes contact with the skin ( FIG. 4   b ). When the cover  70  is pushed open by the front end  78  of the case  56 , the sensitive lancing tip  40  is protected from damage. This is followed by the lancing advance of the lancing element  14  up to the maximum penetration depth ( FIG. 4   c ) and the subsequent return movement ( FIG. 4   d ). A separate advance movement of the detection element  16  then takes place in the lancing axis defined thereby such that the test reagent  46  at the front end comes nearer to the lancing member  40  and dips into the collection volume  44  ( FIG. 4   e ). 
         [0036]    In the puncture according to  FIG. 4   c  the relatively large distance between the front face or receiving element of detection element  16  and lancing member  40  protects the test person from contamination with the test reagent  46 . Furthermore, this distance also allows a simplified sterilization of the lancing tip  40  during manufacture. In this case an electron beam can be focussed onto the tip  40  without the radiation damaging the test reagent  46  located at a suitable distance or making it unusable. In particular special barriers between the test reagent and lancing tip can be dispensed with. 
         [0037]    While exemplary embodiments incorporating the principles of the present invention have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.