Device and method for testing body fluidsThe invention relates to a device for testing body fluids, in particular for blood glucose testing, comprising a lancing element which can be pierced into a body part along a lancing axis and a receiving element (Aufnahmeelement) which is designed for detecting the contents of the body fluid, wherein the lancing element has a collection volume (Sammelvolumen) for collecting the body fluid obtained by lancing, and the receiving element can be loaded (beaufschlagar) with body fluid from the collection volume. The invention further relates to a corresponding testing method and to a method for disinfecting such a device in the form of a disposable component (Einwegteil).
In the applicant's earlier application document PCT/EP2006/009945, a test element for testing of body fluids for analytical purposes, in particular for determining the blood glucose concentration, is described. This results in a lancing element with a collecting region for body fluid, wherein the collecting region is formed by a collecting recess extending longitudinally in the lancing direction, and wherein the fixedly integrated light guide is arranged with its distal end in a proximal measuring region of the collecting recess. Thus, optical detection of analytes can be achieved via microfluidic liquid transfer within the lancing structure.
Starting from this, the invention is based on the object of further developing the systems known from the prior art and of optimizing a device and a method of the type described at the outset from the point of view of reliable sample handling, wherein as small a sample volume as possible is sought after in the case of reduced pricking pain, and of simplifying the production.
To achieve the object, combinations of features described in the independent claims are proposed. Advantageous embodiments and developments of the invention result from the dependent claims.
The invention proceeds from the idea of avoiding an excess volume for capillary sample transport and instead bringing the receiving element into direct contact with the sample by means of a suitable relative movement. Accordingly, it is proposed according to the invention that the lancing element and the receiving element are arranged in a lancing axis so as to be movable relative to one another, wherein the receiving element is arranged in an initial position outside a collection volume of the lancing element such that the receiving element is not in contact with the body during lancing, and wherein the receiving element is immersed in the collection volume in the lancing direction during a transfer phase following the lancing and is thereby engaged in the collection volume in the receiving position. In this way, sufficient liquid wetting of the receiving element is likewise possible without capillary transport of liquid, wherein malfunctions are avoided as far as possible by suitable immersion. It is therefore possible to carry out a complete measurement sequence as automatically as possible with the minimum sample volume in a miniaturized configuration. The receiving element can serve here merely as an intermediary for further sample transport or can also serve directly as a sensing element.
In a preferred embodiment, the distance between the lancing device (stethorgan) of the lancing element and the receiving element is smaller in the transfer phase than in the preceding lancing phase. In this way, a physical contact of the receiving element is avoided during the lancing phase, while the sample volume can be reduced accordingly by reducing the distance.
Advantageously, the receiving element can be introduced 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 collecting volume by means of a feed drive.
In order to be able to use a drive unit that is fixed relative to the instrument, it is advantageous if the lancing element and/or the receiving element have a docking structure (andockstrucktur) at the proximal end for a releasable drive coupling.
For a simplified measuring procedure, it is advantageous if the lancing element is mounted in a linear guide, preferably formed by the associated cartridge housing.
A constructively advantageous embodiment provides that the receiving element engages into a recess of the lancing element which opens into the collection volume.
It is particularly advantageous if the lancing element and the receiving element are designed as disposable parts (zusammengehoerig) in a corresponding manner. In this way, the measurement can be performed with a high user comfort. A further development in this respect is achieved by a receptacle, in particular a disk receptacle, a drum receptacle or a stack receptacle, which is designed to accommodate a plurality of lancing elements and associated receiving elements.
For further increased measurement integration, it is advantageous if the receiving element has a measuring device (Messorgan) for optical or electrochemical measurements in the received body fluid. It is preferred here if the measuring part is coated with a test agent which reacts with the substance contained in the body fluid in liquid contact.
For the transmission of signals to the instrument unit, it is advantageous if the receiving element can be connected to the measuring unit via a light guide guided in the lancing element or is already connected to the measuring unit via a light guide guided in the lancing element.
In order to optimize the absorption of liquid, it is advantageous if the collecting volume is formed by a single-sided open groove or by a double-sided open slit of the lancing element.
A particular aspect of the invention is that the collection volume receives less than 50nl, preferably less than 10nl of body fluid or that the collection volume receives less than 50nl, preferably less than 10nl of body fluid. In this way, pain can be further reduced when obtaining a sample and thus an improvement in user acceptance can be achieved. Due to this particular sample collection, it is sufficient if the receiving element is applied with a portion of the body fluid (Aliquot) from the collection volume at the distal front side, wherein this portion is less than 5nl, preferably less than 1 nl.
The object of the invention also includes an lancing device for the use of at least one device according to the invention which is designed as a disposable part with a lancing drive which can be triggered by a user, wherein the disposable part is mounted in a first position in the device in the non-use state and, after lancing, is supported in the use state in a second position in the device which is spaced apart from the first position. Thereby, the preparation process and the disposal process can be ensured without the user's operation.
In terms of method, the object mentioned at the outset is achieved in that during a transfer phase following the piercing, the lancing element and the receiving element are moved relative to one another on a lancing axis in such a way that the receiving element is immersed in the collection volume in the lancing direction. The advantages already mentioned above also exist here.
In an advantageous embodiment, the distance between the receiving element and the distal lancing tool of the lancing element is reduced in a transfer phase, wherein the receiving element is moved together with the lancing element during the lancing operation or the lancing element is driven to perform a reciprocating lancing operation while the receiving element remains stationary.
Advantageously, the lancing element is located outside the body part containing the body fluid during the transfer phase, wherein it is further advantageous to perform an optical or electrochemical measurement in the received body fluid via the receiving element (as a measuring component).
Another aspect of the invention is a method for sterilization of a device according to the invention configured as a disposable component, in which method a receiving element coated with a test reagent is held at a distance from a lancing tool distal to the lancing element, and the lancing tool is preferably irradiated with electron radiation (elektronephl). It is possible here to focus the radiation (in particular electron radiation) on the lancing device in such a way and/or to select the spacing between the receiving element and the lancing device in such a way that the test agent is not damaged by the radiation.
The invention will be further elucidated below on the basis of an embodiment which is schematically shown in the drawing. Wherein
FIG. 1 shows in a block diagram an instrument for blood glucose measurement with a disposable lancing and detection element;
FIGS. 1b and 1c show the lancing and testing element according to FIG. 1a in a lancing and testing position;
FIG. 2 shows in top view a disk-shaped receptacle with an activated lancing and detection element in a different position;
FIG. 3 shows another embodiment of the lancing and detection element in two positions in a perspective view;
fig. 4 shows a further embodiment of the lancing and detection element in different positions in axial section.
The diagnostic measuring assembly shown in the figures comprises an analysis device 10 for blood glucose measurement and at least one test element 12 which can be inserted therein as a consumable part for single use, the test element 12 having a lancing element 14 and a receiving or detection element (Aufnahme-bzw. Nachweissement) 16.
As can be seen from fig. 1, the analysis device 10 has a device housing 18, which device housing 18 carries a holder 20, for example for a finger 22, in the region of a puncture opening 24. The lancing element 14 is mounted in a linear guide 26 within the housing 18 to effect a reciprocating lancing motion relative to the supported finger 22. For this purpose, the lancing element 14 can be releasably connected to a push rod 30 of a lancing drive 32 via a proximal interface 28. For the optical detection of glucose in a blood sample obtained by means of the lancing element 14, a detection unit 34 is provided inside the instrument, which can be coupled to a light guide 38 of the detection element 16 via a flexible line 36.
The lancing element 14 is formed as a flat component, for example made of stainless steel plate, and has a distal tip 40 as a lancing device, behind which a collecting volume 44 is located, which is defined by a slit 42 which is open on both sides.
The detection element 16 engages with its light guide into the slot 42, the front surface of the light guide 38, which is coated with the test agent 46, being aligned facing the collection volume 44. The test reagent 46 changes color when blood is applied thereto, due to the glucose contained therein, so that optical detection by means of the detection unit 34 via the light conductors 38, 36 is possible on the basis of the change in color. The measurement results may be displayed to the user for in situ self-verification.
As can be seen from fig. 1a, b, c, the lancing element 14 is arranged in a guide 26 so as to be linearly movable relative to the detection element 16 held fixed to the instrument. That is, lancing element 14 can be moved back and forth along lancing axis 48 so that a puncture into a body part can be made and a blood sample obtained thereby can be transferred onto test reagent 46. In the initial position according to fig. 1a, the lancing movement can be triggered by the user after the finger 22 has been placed on. In a subsequent lancing phase the lancing device 40 penetrates into the blood-providing skin layer 50 at a suitable setting of the lancing depth. During the retraction movement, which is typically performed relatively slowly compared to the rapid forward movement during lancing, body fluid 52 (blood, if desired interstitial fluid) is received in the collection volume 44. In this case, a small amount of blood (in the range of 10 nanoliters or less) is sufficient. In the subsequent transfer phase, a portion of the collected body fluid 52 is transferred onto the detection element 16 by a reverse movement of the lancing element 14, wherein the reagent layer 46 is immersed proximally into the collection volume 44 as a sensing element. Due to the reduced spacing between the sensing element (test reagent 46) and the lancing device 40 and/or the collection volume 44, there is no need to absorb excess fluid volume for capillary transport of body fluid. A very small partial volume of about 1 nanoliter is sufficient for the actual detection reaction at the tip of the light conductor.
Fig. 2 illustrates a possible use of a plurality of test elements 12 in a disk magazine 54. By rotating such a disk magazine 54 in the instrument 10, the test elements can be brought into the activation position (test elements 12') in succession. The piercing takes place with an enlarged spacing between the lancing device 40 and the detection element 16 according to fig. 2b, while the liquid transfer takes place by a reduced spacing in the transfer phase according to fig. 2 c. The used test element may then be discarded by advancement of the magazine 54.
Fig. 3 shows an embodiment of the test element 12 in a cylindrical cartridge housing 56, which cartridge housing 56 forms part of the disposable article and forms the guide 26 for the U-shaped longitudinally slotted lancing element 14 with a central recess 58. The fiber optic rod 38, which is disposed in the slot 42 of the lancing element 14, is also fixedly connected to the cartridge housing 56 as part of the consumable. The fiber optic rod 38 is coated with the test reagent 46 on the front side and can be docked on the rear side to the light guide 36 (the light guide 36 is coupled to the detection unit 34 on the instrument side). For this purpose, a jaw-like claw coupling 60 is provided as a docking structure 28 at the lancing element 14, which claw coupling 60 automatically comes into engagement with the head 62 of the drive ram 30 in a form-fitting manner (formschluessig) in a feed movement (arrow 64). For this purpose, a starting ramp 66 is formed on the inside of the cartridge housing 60, which closes the elastically spread claw teeth 60, so that a retraction movement is likewise possible after the blood collection. In this exemplary embodiment, it is possible for the cartridge 56 to be moved by a separate feed drive to the finger 22, with the free end face side serving as a reference surface for the lancing depth being pressed against the skin and stabilizing it.
In the embodiment shown in fig. 4, likewise, identical components are provided with the same reference symbols as described above. In the initial position of fig. 4a, the cartridge housing 56 is closed off aseptically at its front opening by a sealing flap 70. Thus, the test agent 46 is protected from environmental influences (especially from moisture). Cartridge housing 56, lancing element 14, and detection element 16 are each provided at a proximal end with a docking structure 72, 28, 74 for a separate drive coupling. In the process sequence shown, the sealing flap 70 is first opened and a frontal skin contact is established by advancing the entire disposable part 76 (fig. 4 b). The vulnerable piercing tip 40 is protected as the flap 70 is pushed away by the end face side 78 of the cartridge housing 56. The lancing of the lancing element 14 is then carried out until the maximum puncture depth is reached (fig. 4c) and a subsequent retraction movement is carried out (fig. 4 d). Then, an independent feed movement of the detection element 16 is carried out on the lancing axis defined here, so that the end face-side test agent 46 comes closer to the lancing device 40 and is thereby immersed into the collection volume 44 (fig. 4 e).
In the puncture according to fig. 4c, the relatively large distance between the detection element 16 and the puncture device 40 protects the test person from being contaminated with test reagents. Furthermore, this spacing also makes possible a simplified sterilization of the piercing tip 40 during the production process. Here, the electron beam can be focused on the tip 40 without the beam damaging or disabling the test agent 46 (the test agent 46 is at an appropriate distance). In particular, here, the special barrier between the test agent and the lancing tip can be discarded.