CA2598770C

CA2598770C - Puncturing system for withdrawing a body fluid

Info

Publication number: CA2598770C
Application number: CA2598770A
Authority: CA
Inventors: Frank Deck; Ortrud Quarder; Thomas Weiss; Christian Hoerauf; Michael Kistner; Ahmet Konya; Herbert Harttig; Felix Baader; Hans List; Karl-Peter Ebert
Original assignee: F Hoffmann La Roche AG
Current assignee: F Hoffmann La Roche AG
Priority date: 2005-03-03
Filing date: 2006-03-02
Publication date: 2011-07-19
Anticipated expiration: 2026-03-02
Also published as: CN101146477A; HK1118438A1; EP1865846A2; WO2006092309A8; JP2008531156A; CN101146477B; CA2598770A1; US20080082023A1; WO2006092309A3; JP4573878B2; WO2006092309A2; US8231547B2; EP1865846B1

Abstract

A puncturing system for with-drawing a body fluid from the skin of a human or animal, comprising a disposable puncturing unit (1), which has a needle element (6) for piercing into the skin, a puncturing instrument (2), which includes a puncturing drive (4), by which a puncturing movement of a puncturing unit (1), which is coupled to the puncturing drive (4) by means of a coupling mechanism (3), is driven, a predefined value of the puncturing depth being ensured by means of a puncturing depth reference element (10), which has a skin contact area. (11), and the predefined value of the puncturing depth being determined by the distance in the piercing direction between the skin contact area (11) and the position of the needle tip at the reversal point of the puncturing movement.

The puncturing depth reference element (10) is connected to the needle element (6) and coupled to the drive in such a manner that it moves together with the needle element (1) during at least a part of the forward phase and has a defined longitudinal position in the piercing direction in relation to the needle element (6) at least at the reversal point of the puncturing movement.

Description

Applicant: Roche Diagnostics GmbH, 68298 Mannheim, DE
F. Hoffmann-La Roche AG, Basel, Switzerland Puncturing system for withdrawing a body fluid The present invention relates to a puncturing system for withdrawing a body fluid from the skin of a human or animal- The body fluid is typically blood. Many applications, however, are concerned with obtaining a sample of interstitial liquid. Hereafter, reference is made to blood as an example, also for other body fluids obtainable from the skin, without restriction of the generality.
The system includes a single-use (disposable) puncturing unit, comprising a needle element for piercing into the skin and a puncturing instrument containing a drive for the puncturing movement. A puncturing unit particularly suitable for use in such a system also belongs to the subject matter of the present invention.

Disposable puncturing units have been used for some time to withdraw a small quantity of blood from a body part (usually from a finger or earlobe) for analytic-diagnostic purposes. In this context, the puncturing units are typically designated as lancets. Lancets intended for manual piercing are described, for example, in US Patent 3,789,830. They are typically only used by medically trained personnel. Nonetheless, the piercing is connected with significant pain.

Puncturing instruments which contain a puncturing drive have been used for some time. The puncturing instrument may be a disposable item comprising a permanently integrated lancet. However, typically it is usable a plurality of times and has a holder, by means of which a lancet may be replaceably coupled to the puncturing drive. Because the devices and lancets are elements which are mutually adapted and are provided by the same producer, they are designated as a "puncturing system" or "blood withdrawal system".

Usually a spring is used as the drive element for the lancet drive located in a housing of the puncturing instrument, A lancet guide makes sure that the puncturing movement occurs on a predetermined movement path. At the beginning of development, very simple constructions of the drive were typical, in which the lancet was attached directly to one end of a i5 pressure spring inside an elongated housing. Such a puncturing system is known, for example, from US Patent 4,469,110. Another early construction of a puncturing instrument is described in US Patent 4,442,836. The movement of the lancet in the direction toward the skin surface up to a reversal point (forward phase of the puncturing movement) is driven by a first spring, while a second spring is used as the drive for the retraction movement of the lancet (retraction phase of the puncturing movement). The second spring is effective after the force coupling between the first spring and the lancet has been interrupted.

23 In typical constructions, the puncturing instruments have at their front end (in the piercing direction) an exit opening, from which the tip of the lancet exits for a short time to produce a wound in a body part, against which the front end of the puncturing instrument is pressed. The puncturing depth is defined by the distance in the piercing direction between the position of the lancet tip at the reversal point of the lancet movement and the plane of a skin contact area, which annularly surrounds the exit opening and contacts the skin at the instant of piercing. The front end of the puncturing instrument including the skin contact area thus forms a puncturing depth reference element which ensures that the puncturing depth has a predefined value.

To control the puncturing depth, it is typical to limit the movement path of the lancet in the piercing direction by means of a stop connected to the lancet which hits a corresponding stop face in the housing of the puncturing instrument. This housing-stop construction is disclosed, for example, in US Patent 4,469,110. In the case of the drive comprising two springs described in US Patent 4,442,836, a defined position of the reversal point of the lancet movement is allegedly ensured by interrupting the force transmission between the drive spring and the lancet at a io defined point of the movement path-Blood withdrawal systems of this type do not meet the high requirements which are to be fulfilled if regular monitoring of specific analytical values of the blood is necessary. This is true in particular for diabetics needing is frequent analysis of the blood sugar level to keep it as continuously as possible within specific limits by adapting insulin injections to the demand (which varies substantially as a function of food intake, physical activity, etc.). It has been proven by extensive scientific work that a dramatic reduction of the most severe late damage of diabetes mellitus (for 20 example, retinopathy with resulting blindness of the patient) may be achieved by intensive treatment using at least four blood analyses per day.

This intensive treatment requires that the blood withdrawal causes the 25 least possible pain. Great progress has been achieved in this regard by the design described in US Patent 5,318,584, which is based, inter alia, on the finding that the pain connected with obtaining blood may be significantly reduced if the puncturing system is made in such a manner that the piercing (even if new disposable lancets are used in each case 30 for the piercing actions) is reproducible at a quality which was not achieved before. To ensure this, a lancet drive having a drive rotor is used. A drive spring acts on one side of the rotor (drive side). The other side (output-side) is coupled by a coupling mechanism to the lancet in such a manner that the rotation of the drive rotor is converted into the 3 5 desired puncturing movement. The output-side coupling mechanism is designed (by means of a control curve) in such a manner that the lancet is coupled to the drive rotor practically without play during the entire puncturing movement (comprising forward phase and retraction phase) whereby the lancet movement is completely controlled by the corresponding movement of the drive rotor. The shock caused by abutting of the two stops in a drive type comprising housing stops (US
Patent 4,469,110) is avoided by this construction. In addition, due to the permanent coupling without play of the lancet to the drive rotor, an exactly reproducible position of the reversal point of the lancet movement io during repeated puncturing movements is ensured, which was not achieved in the drive type of US Patent 4,442,836.

The present invention not only relates to puncturing systems which only serve for obtaining a blood droplet for subsequent analysis by means of another device- Rather, it is particularly directed to so-called integrated systems, by means of which not only the blood withdrawal, but also the analysis is performed with a minimum of additional handling steps by the user. This causes additional requirements, which result, inter alia, from the limited space if both functions are to be housed in one device housing which (for handling reasons) must be as small as possible.

Integrated systems are described in US Patents 5,029,583 and 5,514,152 in which the blood is obtained by means of a lancet needle, whose movement path in the piercing direction is limited by a housing stop, as in US Patent 4,469,110. In US Patent 5,514,152, the obtained blood droplet is transferred to an analysis sensor with the aid of a capillary channel running in the device housing.

US Patent 5,938,679 describes a puncturing system with a puncturing a o unit optionally provided with capillary tubes, through which blood may be suctioned into the interior of the device with the aid of capillary forces.
This is an example of a puncturing system whose needle element has a capillary channel through which a body fluid may be transported from the skin into the interior of the puncturing unit. A further example of such a puncturing system is described in US Patent Application - - - - " - - CA 02598770 2007-08-22 US 2003/0018282 Al. The puncturing unit not only comprises the needle for piercing the skin, including a capillary channel for transporting the sample, but also a detection area containing reagents. Such a puncturing unit, which simultaneously has a receiving area for the sample (formed s by a capillary-active absorption layer and/or hollow chamber) and preferably also contains the reagents required for the analysis, is designated hereafter as a "microsampler". Reference is made to the cited US patent application and the documents cited therein, particularly US
Patent 5,801,057, providing more specific details about microsamplers.
Microsamplers of various designs may be used in the context of the present invention, taking into account the special features described here.

The present invention is generally directed to puncturing systems of various types, the needle element which pierces into the skin being e.g. a solid needle (as in the mentioned lancets) or a capillary needle (with an open capillary or formed as a closed hollow needle). If reference is made to lancets or other special embodiments, this is for exemplary purposes and without restriction of the generality. The explanations are in principle applicable also for other embodiments.

On this basis, the present invention addresses the object to provide a puncturing system in which a reproducible puncturing depth is ensured in an improved manner and which is particularly suitable for use in integrated analysis systems.

The object is achieved by .a puncturing system for withdrawing a body fluid from the skin of a human or animal, comprising a disposable puncturing unit, which has a needle element for piercing into the skin, a puncturing instrument including a puncturing drive, by which a puncturing movement of a puncturing unit, which is coupled by means of a coupling mechanism to the puncturing drive, is driven, wherein - in a forward phase of the puncturing movement, the needle element is moved along a predetermined movement path in a piercing direction until its tip penetrates into the skin and in a retraction phase of the puncturing movement, the needle element is retracted again after reaching a reversal point corresponding to the puncturing depth in the skin, a predefined value of the puncturing depth is ensured by means of a puncturing depth reference element which has a skin contact area, and the predefined value of the puncturing depth is determined by the distance in the piercing direction between the skin contact area and the position of the needle tip at the reversal point of the puncturing IQ movement, the puncturing depth reference element being connected to the needle element and coupled to the drive in such a manner that it is moved together with the needle element at least during a part of the forward phase, and is - has a defined longitudinal position in the piercing direction in relation to the needle element at least at the reversal point of the puncturing movement.

The subject matter of the present invention also includes a disposable 20 puncturing unit for withdrawing a body fluid from the skin of a human or animal, in particular as a component of a system according to any one of the preceding claims, comprising a needle element for piercing into the skin in a piercing direction corresponding to the orientation of the needle tip and a puncturing depth reference element, by which a maximum 25 puncturing depth of the needle in the skin is limited when a skin contact area of the puncturing depth reference element contacts the skin, whereby a predefined value of the puncturing depth is ensured, the longitudinal position in the piercing direction of the puncturing depth reference element in relation to the needle element and thus the distance 30 between the skin contact area and the needle tip being changeable to set the predefined puncturing depth.

In contrast to the customary puncturing systems, in which the puncturing depth reference element was formed by a fixed component of the housing, normally the front end of the housing of the puncturing instrument, it is characteristic for the present invention that the puncturing depth reference element is carried along with the needle element during at least a part of the forward phase. The puncturing depth is determined by the "protruding distance" of the needle tip in relation to the skin contact area, the latter being located at the front end, in the piercing direction, of the puncturing depth reference element. This protruding distance is preferably adjustable to allow the setting of various puncturing depths as a function of the requirements of the user.
The puncturing instrument may be a single-use (disposable) product in which the puncturing unit is permanently connected to the puncturing drive (via the coupling mechanism). However, preferably the puncturing instrument is usable a plurality of times and has a holder, by means of which a disposable puncturing unit may be replaceably coupled to the puncturing drive.

As explained in more detail hereafter, the adjustability of the needle protruding distance is according to a preferred embodiment of the present invention achieved by a design of the puncturing instrument having separate couplers for the needle element on one hand and the puncturing depth reference element on the other hand. The term "coupler" is in this context generally to be understood as a connection by which forces are transmitted. As will be explained in more detail hereafter, for some embodiments of the present invention it is sufficient if the coupler only acts in one movement direction (unidirectionally).
However, preferably at least the needle element coupler acts bidirectionally. In any case, the coupler includes a positioning part having a stop which cooperates with a corresponding stop of the needle element or the puncturing depth reference element in such a manner that the longitudinal position of the needle element or the puncturing depth reference element is, at least at the reversal point of the puncturing movement, determined by the contact of the stop faces. The needle protruding distance is determined by the relative position in the puncturing direction of the two positioning parts and is thus adjustable by changing this relative position.

According to one embodiment, the needle protruding distance is set before the start of the puncturing movement and then remains constant at least up to the reversal point, i.e., during the forward phase of the puncturing movement. This means that the puncturing depth reference element is moved during the forward phase at the same speed as the needle element, i.e., synchronously therewith. According to another io embodiment, the relative longitudinal position of the two elements of the puncturing unit changes during the forward phase. However, in any case the relative longitudinal position must have a defined value at the instant at which the puncturing movement reaches the reversal point. This value corresponds to the predetermined value-of the puncturing depth-The fact that according to the present invention the puncturing depth element includes a skin contact area which is moved during the puncturing movement does not mean that no fixed skin contact area is provided in devices according to the present invention. Rather, according 20 to a preferred embodiment - which in this respect corresponds to known systems - a second skin contact area is provided at the front end of the puncturing instrument, which annularly surrounds a housing opening and by means of which the instrument is pressed against the skin during use.
In contrast to known devices, however, this housing skin contact area is 25 not used as a puncturing depth reference. The puncturing depth reference is formed by the reference element skin contact area.

The housing opening enclosed by the housing skin contact area preferably has a relatively large diameter of, for example, at least 3 mm, 30 preferably at least 5 mm. Such a relatively large opening allows additional functions which are in particular advantageous in integrated systems for the blood sampling required for the analysis. When the device is pressed onto the skin, it bulges because of its elasticity into the relatively large opening, The extent to which this bulging of the skin into 35 the housing opening occurs, is a function of various factors, in particular the contact pressure and the elasticity of the skin. This causes a variance of the position of the skin surface, which is designated herein as the "Z
variance". The invention allows good reproducibility of the puncturing depth in spite of this Z variance.
According to a preferred embodiment, the puncturing instrument is equipped with a "stroke adaptor", by which the reversal point of the puncturing movement is at least partially adapted to the actual position of the skin surface and thus the Z variance occuring during use of the io puncturing system is at least partially compensated. Accordingly, the term "stroke adaptor" is used to designate a device for adapting the puncturing movement, by which an at least approximate adaptation of the longitudinal position of its reversal point to the actual position of the skin surface is achieved. The stroke adaptor may therefore also be s designated as a stroke adaptation mechanism. Various embodiments are possible:

- A design in which the actual position of the skin surface is detected (e.g., using mechanical, electronic, or optical-electroni(; means) and the puncturing movement is adapted to the actual position of the skin 20 surface (before or during the forward phase) by control means, which act on the puncturing drive, its positioning in the puncturing instrument, or the coupling mechanism, is designated as a "actively controlled stroke adaptor".

- Alternatively, the stroke adaptor may be implemented by means of 25 an elastic element which causes "buffering" of the puncturing movement. This elastic element may be 'a component of the puncturing drive or of the coupling mechanism between puncturing drive and lancet. The buffering may also be achieved by elastic mounting of the puncturing drive. Particularly suitable elastic element 30 are metal springs, but elastic elements which comprise elastomeric materials including rubber may also be used.

- The stroke adaptor may also be implemented using' a friction coupling, in which two coupler elements are connected to one another by means of friction in such a manner that they allow the transmission of a limiterd, force in the direction of the puncturing movement, but, if a force: acting on the coupler exceeds a limiting value, the two elements are movable relative to each other in such a manner that the force transmission in the direction of the puncturing s movement is interrupted.

These design principles may also be used in combination.

An important advantage of the present invention is that it allows to 10 achieve a well reproducible puncturing depth by means of a very space-saving construction which is mechanically relatively simple. It is thus especially suitable for integrated systems, in which the most compact design possible is desired for the reasons explained above. Due to the relatively simple construction, the device can be produced at favorable cost.

A further advantage results from the fact that the reproducibility of the puncturing depth is largely independent of the construction of the puncturing drive. The present invention may be implemented in combination with differing puncturing drive variants. In particular, the drive speed and further details of the puncturing movement may be adapted to the particular requirements- If necessary, the drive may be such that the puncturing unit is rapidly retracted after the piercing and thus provides space for subsequent analysis functions, in particular the taking-up of the sample into an analysis element.

For a plurality of embodiments of the present invention, a type of puncturing drive is preferred in which a solid (non-elastic) drive element is moved from a starting position into a final position and this movement of the drive element is transformed by means of the coupling mechanism into the puncturing movement. The drive element is preferably a rotor rotating around a central axis, but other drive elements, such as pivot or knee levers, are known and are suitable for the present invention depending on the requirements in the specific case. The movement of the drive element is driven by spring force or other known means, for example, electrically or electromagnetically.

In any case, the puncturing drive generates a translational movement of the needle element between a starting position and the reversal point of the puncturing movement. The distance between these points of the movement of the puncturing unit is designated as the stroke of the puncturing movement.

io According to a preferred embodiment of the invention, there is provided a puncturing system for withdrawing a body fluid from the skin of a human or animal, comprising: a needle element (6) for piercing into the skin; a puncturing instrument (2), which includes a puncturing drive (4), by which a puncturing movement (24) of the needle element (6), which is coupled is to the puncturing drive (4) by means of a coupling mechanism (3), is driven; wherein (a) in a forward phase of the puncturing movement (24), the needle element (6) is moved along a predetermined movement path in a piercing direction until its tip (13) penetrates into the skin and, in a retraction phase of the puncturing movement (24), the needle element 20 (6) is retracted after reaching a reversal point corresponding to the puncturing depth in the skin; (b) a predefined value of the puncturing depth is ensured by means of a puncturing depth reference element (10), which has a skin contact area (11), the predefined value of the puncturing depth being determined by the distance in the piercing 25 direction, at the reversal point of the puncturing movement, between the skin contact area (11) and the position of the tip (13) of the needle element (6); (c) the needle element (6) and the puncturing depth reference element (10) are separate elements which can be shifted relative to each other in the piercing direction, and the puncturing depth 30 is adjustable by changing the distance (d) existing at the reversal point between the skin contact area (11) of the puncturing depth reference element (10) and the tip (13) of the needle element (6); (d) the puncturing depth reference element (10) is coupled to the drive by the coupling mechanism (3) in such a manner that it is moved together with the 35 needle element (6) at least during a part of the forward phase of the lla puncturing movement, and has a defined longitudinal position in the piercing direction in relation to the needle element (6) at least at the reversal point of the puncturing movement; and (e) the coupling mechanism (3) includes a needle element coupler (16) comprising a needle element positioning part (16a), which has a first stop (16b), cooperating with a corresponding second stop (6b) of the needle element (6) in such a manner that the longitudinal position of the needle element (6) is at least at the reversal point of the puncturing movement determined by the contact of said first and second stops (16b, 6b), the io coupling mechanism (3) includes a reference element coupler (17) comprising a reference element positioning part (17a), which has a third stop (17b), cooperating with a corresponding fourth stop (10b) of the puncturing depth reference element (10) in such a manner that the longitudinal position of the puncturing depth reference element (10) is determined, at least at the reversal point of the puncturing movement, by the contact of said third and fourth stops (17b, 10b), and the longitudinal position at which the needle element positioning part (16a) and the reference element positioning part (17a) are located at the reversal point in relation to one another is changeable for adjusting the puncturing depth.

According to a further preferred embodiment of the invention, there is provided a disposable puncturing unit (1) for withdrawing a body fluid from the skin of a human or animal, for use as a component of a system in which one disposable puncturing unit (1) at a time may be replaceably coupled to a puncturing drive (4) provided in a puncturing instrument (2) of the system, the puncturing unit comprising: a needle element (6) for piercing into the skin in a piercing direction; and a puncturing depth reference element (10), by which a maximum puncturing depth of the needle in the skin is limited in that a skin contact area (11) of the puncturing depth reference element (10) contacts the skin, whereby a predefined value of the puncturing depth is ensured; wherein (a) the longitudinal position in the piercing direction (24) of the puncturing depth reference element (10) in relation to the needle element (6) and thus the distance between the skin contact area (11) and the needle tip (13) is lib changeable to adjust the predefined puncturing depth; (b) the puncturing unit (1) is during the puncturing movement (24) coupled to the puncturing drive (4) by means of a coupling mechanism (3); (c) the coupling mechanism (3) comprises a needle element positioning part (16a), and the needle element (6) has a coupling structure, which cooperates with a corresponding coupling profile of the needle element positioning part (16a) for coupling the needle element (6) to the needle element positioning part (16a); and (d) the coupling mechanism also comprises a reference element positioning part and the puncturing depth reference element (10) also has a coupling structure, which cooperates with a corresponding coupling profile of the reference element positioning part for coupling the reference element to the reference element positioning part.

The present invention is explained in more detail hereafter on the basis of preferred embodiments shown in the figures. The special features shown therein may be used individually or in combination to provide preferred embodiments of the present invention.

Figure 1 shows a schematic sectional illustration of those components of a first embodiment of a puncturing system which are essential in connection with the present invention;

Figure 2 shows an illustration corresponding to figure 1 in four operational positions a through d of the puncturing system;

Figure 3 shows a schematic side view of a first embodiment of a puncturing drive comprising a stroke adaptor suitable for the present invention;

Figure 4 shows a schematic side view of a second embodiment of a puncturing drive suitable for the present invention;

Figure 5 shows four operational positions of a puncturing system comprising a further embodiment of a stroke adaptor;

Figure 6 shows a schematic sectional view of a puncturing unit according to the present invention;

Figure 7 shows a schematic sectional view of a further embodiment of a puncturing unit according to the present invention;

Figure 8 shows a view of the lancet receptacle of a puncturing unit from figure 6;

Figure 9 shows a view of the bottom side of the lancet body of a lancet of the puncturing unit of figure 6:

s Figure 10 shows a side view of a further embodiment of a puncturing unit according to the present invention embodied as a microsampler, and the coupling mechanism of an associated puncturing instrument which forms a puncturing system with the microsampler;

Figure 11 shows a front view of the components shown in figure 10;
Figure 12 shows a view from below of the microsampler shown in figure 10;

Figure 13 shows a view from above of the microsampler shown in figure 10;

i s Figure 14 shows a side view of a microsampler similar to figure 11 in four different operational positions a through d;

Figure 15 shows a position-time diagram of a typical puncturing movement of a puncturing system according to the present invention;

Figure 16 shows a perspective illustration of a part of a known puncturing system including lancets in a magazine;

Figure 17 shows a sectional illustration of a part of an embodiment of the present invention including puncturing units in a magazine;

Figure 18 shows a perspective illustration of a further embodiment of a puncturing system according to the present invention without its housing;

Figure 19 shows a sectional illustration of the puncturing system of figure 18;

Figure 20 shows a position-time diagram of a further typical puncturing movement of a puncturing system according to the present invention;

Figure 21 shows a schematic side view of a puncturing system similar to figure 18 in four operational positions A through D;

Figure 22 shows a side view of a further embodiment of a puncturing system according to the present invention without its housing;

io Figure 23 shows a longitudinal section of the puncturing system from figure 22;

Figure 24 shows a perspective illustration of the puncturing system from figure 22;

Figure 25 shows a side view (partially in section) of a further embodiment of a puncturing system according to the present invention;

Figure 26 shows a schematic cross-section (not to scale) through a needle element strip Figures 27 through 30 show a further embodiment of a puncturing 20 system according to the present invention in four operational positions, each in a perspective view (A) and in a side view, partially in section (B).

Figures 31 through 33 show a partial cross-sectional illustration of a further embodiment of a puncturing system according to 25 the present invention in three operational positions.

When the words "front" and "rear" are used to identify the localization of components, this relates to the piercing direction. Thus, for example, the end of the puncturing unit or the puncturing instrument by which or at 30 which the piercing occurs, respectively, is designated as the front end and the diametrically opposite end is designated as the rear end. The terms "longitudinal direction" and "longitudinal position" relate to the spatial direction of the puncturing movement, which is also designated as the Z direction and corresponds to the main axis of typical elongated ("pencil-shaped") puncturing instruments.

Figures 1 and 2 show components which are important for the function of s a puncturing system according to the present invention, namely a disposable puncturing unit 1 and parts of a puncturing instrument 2 (not shown in its entirety). These parts mainly form the coupling mechanism 3 for connecting a puncturing unit 1 to a puncturing drive 4 (only symbolically shown in these figures).
so The puncturing unit 1 has two main components, namely a needle element, identified as a whole by 6, including a needle element body 7 and a needle 8, as well as a puncturing depth reference element 10 having a skin contact area 11 and a reference element body 12, which is extends from the skin contact area 11 to the rear and encloses the body part 7 of the needle element 6. When the needle 8 is located in the operational position shown in figures 1 and 2a, its tip 13 is enclosed by a sterile protector 14, preferably made from a plastic material which tightly encloses the needle tip 134 and thus ensures its sterility during the 20 storage of the puncturing unit 1.

Figures 1 and 2a show the delivery (before use) state of the puncturing unit 1. In this state, the needle element 6 is fixed by fixing means 15 in a defined longitudinal position inside the reference element body 12. The 25 fixing means 15 (for example, in the form of the nubs engaging in matching recesses shown) are implemented in such a manner that the fixing is disengaged during the usage of the puncturing unit (or at latest during the puncturing movement) when a relative displacement of the needle element 6 in relation to the puncturing depth reference element so 10 is necessary, as will be explained below.

The coupling mechanism 3 has separate couplers for the elements of the puncturing unit 1, namely a needle element coupler 16 and a reference element coupler 17. Each of the couplers includes a positioning part 16a 3s or 17a comprising a stop 16b or 17b, which cooperates with a corresponding stop 6b of the needle element 6 or 10b of the puncturing depth element 10 in such a manner that, in the coupled state of the elements, their longitudinal position is determined, at least at the reversal point of the puncturing movement, by the contact of these stops.

In the case shown, the positioning part 16a of the needle element coupler 16 is formed by the thickened head 18 of a connecting rod 19, via which the needle element positioning part 16a is connected to the puncturing drive 4. The front face of the head 18 forms the stop 16b. The io corresponding stop 16b of the needle element 6 is formed, in the design shown, by the rear end of the needle 8. Such a construction of the needle element coupler is known from US 2004/0260325, from which further information may be taken.

A sliding body 22, which is seated in a cylindrical bore 23, is used as positioning part 17a of the reference element coupler 17. It has an axial bore with an internal thread 20, into which the connecting rod 19, which has a corresponding external thread 21, is screwed. By mutual rotation of the positioning parts 16a, 17a formed by these components, their longitudinal position in relation to one another can be changed.
Preferably, the reference element positioning part 17a (formed here by the sliding body 22) is rotationally fixed and axially displaceable, while the needle element positioning part 16a (formed here by the head 18 of the positioning rod 19) is connected to a component (here the connecting rod 19) whose position is changeable in the longitudinal direction by rotation around its own axis within the reference element positioning part 17a.

During the puncturing movement, which comprises a forward phase and a retraction phase symbolized in figure 1 by a double arrow 24, the sliding body 22 and the bore 23 act as a guide, whereby the puncturing movement takes place precisely in accordance with the predefined piercing direction.

The reference element coupler is in the case shown designed as a catch hook construction- Catch hooks 25 are provided at the rear end of the reference element body 12, which yields elastically in the radial direction, and engage, upon insertion of the puncturing unit 1, in a corresponding s catch profile 26 provided at the front face of the sliding body 22. Stops 17b and 10b are formed by a front face of the sliding body 22 and the rearmost end of the reference element body 12, respectively.

The needle element coupler 16 and the reference element coupler 17 together form a holder 27, by means of which one disposable puncturing unit 1 at a time may be coupled interchangeably to the puncturing drive 4 of a puncturing instrument 2, which is usable a plurality of times. The insertion of a puncturing unit 1 into the holder 27 is shown. in partial figures a and b of figure 2-is For easier handling, the puncturing unit 1 has an insertion aid 30, molded, for example, by plastic injection molding. It is twisted off by the user after the insertion. During the insertion, the puncturing unit 1 is moved from the starting position shown in figure 2a into the position o shown in figure 2b, in which both the needle element coupler 16 and also the reference element coupler 17 are closed and a fixed connection acting in both axial directions (bidirectional) is formed between the connecting rod 19 and the needle element body 7 and between the sliding body 22 and the reference element body 12. A receptacle 31 25 provided at the rear end of the needle element body 7 encloses the head 18 of the connecting rod 19. The catch hook 25 engages with the corresponding catch profile 26. By comparing partial figures a and b it becomes apparent that the sterile protector 14 has been shifted from the needle tip 13 to the rear, due to the relative movement of the needle o element 6 in relation to the puncturing depth reference element 10.

Setting of the distance in the longitudinal direction of the stop 16b in relation to the stop 17b preferably takes place before the insertion of the puncturing unit 1 wherein the needle element 6 is displaced forward 35 during the insertion procedure (while disengaging the fixing means 15) until the needle tip 13 exits from of the skin contact area 11 such that the protruding distance corresponds to the desired puncturing depth.
However, embodiments are also possible in which the setting of the puncturing depth takes place after the insertion of the puncturing unit in s any case, the exact desired puncturing depth may be set by changing the relative longitudinal position of the positioning parts 16a, 17a. If the setting takes place before the puncturing movement, the protruding distance of the needle tip 13 in relation to the skin contact area 11 remains constant during the puncturing movement and the position of the to puncturing unit is determined during the entire puncturing movement by the actual position of the connecting rod 19_ Figure 2c shows the system components at the moment of piercing into a finger tip 32. The skin rests on a housing skin contact area 33, which is is inclined inward (toward the main axis of the device), conically towards the rear end, and which surrounds the piercing site. It is implemented at the front end of the puncturing instrument 2, which is partially shown in this partial figure. This housing skin contact area 33 allows a sufficiently defined longitudinal position of the skin surface 34 in the surroundings of 20 the puncture site in relation to the puncturing drive 4_ The puncturing depth is determined by the distance of the needle tip 13 from the skin contact area 11. Because the housing opening 35 framed by the device-fixed skin contact area 33 is relatively large, the skin surface 34 bulges into the housing opening 35. The extent of this bulging is a function of 25 various factors, however, in particular the contact pressure and the elasticity of the skin. It results in the above-mentioned 7 variance of the puncture site of the skin surface 34.

Figure 2d shows the system components at the time of ejection of the 30 puncturing unit. For this purpose, an ejector is provided, for example, in the form of the rod 36 shown here, which is moved forward by means of a drive (not shown) to eject the puncturing unit 1. The design is such that the puncturing depth reference element 10 is first shifted forward, while the needle element 6 is still fixed. Due to the resulting relative 35 displacement of the elements 6, 10, the needle tip 13 moves back behind the skin contact area 11 until it is located in a protected position in the interior of the puncturing depth reference element 10. Thereby the danger of injury by the sharp needle tip 13 and the risk of infection connected thereto are avoided.
Figures 3 and 4 show two embodiments of a puncturing drive 4, which have a stroke adaptor designated in general by 38, to adapt the puncturing movement to the actual position of the skin surface (within the Z variance possible between different puncturing actions). As in figures 1 io and 2, the coupling mechanism 3 has in both embodiments a connecting .rod 19 with an external thread 21_ It is seated in a corresponding threaded hole 20 of a sliding body 22. Again the head 18 of the threaded rod 19 forms a positioning part 16a of a needle element coupler, while a positioning part 17a of a reference element coupler is provided at the sliding body 22.

The mechanical design principle of the needle element coupler and the reference element coupler also corresponds to figures 1 and 2. The positioning parts 16a, 17a each have a coupler profile which cooperates with a corresponding coupler profile in a coupler area of the needle or reference element (not shown). Thereby a (preferably bidirectionally acting) coupler having corresponding stop elements is formed.

Deviating from figures 1 and 2, the positioning part 17a shown in figures 3 and 4, is formed by inwardly directed (toward the axis of the connecting rod 19) projections 39 of elastic arms 40. Outwardly open depressions or recesses, in which the projections 39 engage, are provided on the corresponding needle elements.

The positioning parts 16a and 17a form a holder 27 for replaceably receiving a puncturing unit. The longitudinal position of the positioning parts 16a and 17a in relation to one another can be changed by mutual rotation of the connecting rod 19 and the sliding body 22 - again corresponding to figures 1 and 2 - and the needle protruding distance of a coupled-on puncturing unit can be set thereby. The position of the holder 27 and thus a coupled-on puncturing unit is determined at every instant of the puncturing movement by the actual position of the connecting rod 19_ The puncturing drive 4 shown in figure 3 comprises a drive rotor 41 used as drive element which (driven by a drive spring (not shown) and after triggering of a trigger (also riot shown)) makes a rotational movement around its longitudinal axis which corresponds to the axis of the connecting rod 19. The rotation of the drive rotor 41 is converted by a io cam controller 42, which comprises a control curve 43 and a control curve traveler 44, into the translational puncturing movement corresponding to the double arrow 24. Rotor drives of this type are known from various publications (e.g., US Patent 5,318,584 cited above).
Thus an explanation of construction specifics is not necessary-The drive rotor 41 and the cam controller 42 form a rotation-translation-transmission 46, by which the rotation of the drive rotor 41 is converted into the puncturing movement, the reversal point of the puncturing movement being reached when the control curve traveler 44 passes 20 through the apex point 43a of the control curve 43. The rotation-translation-transmission 46 ensures an exactly defined correlation between the actual position of the drive element (rotor) and the puncturing unit. A puncturing drive which meets this condition is designated as "positively controlled".
In the embodiment shown, such a positively controlled puncturing drive is combined with a stroke adaptor using an elastic component 47. In the case shown, this elastic component is a coiled spring 48, which is adapted and arranged such that it forms an elastic bearing for the drive rotor 41. The rotor 41 is mounted axially displaceable in a guide hole 49 in such a manner that it may be moved rearwardly against the force of the coiled spring 48 when the skin contact area of the puncturing depth reference element of a puncturing unit connected to the holder 27 contacts the skin surface during the puncturing movement. This point in time is designated as the "contact instant".

The position of the reversal point is adapted to the Z position of the skin surface by the stroke adaptor, in this case by the elasticity of the elastic component 47. The elastic spring force must be so dimensioned that the s elastic component is not significantly deformed during the puncturing movement before the contact instant. In any case, it should be practically undeformed immediately before the contact instant. The buffer effect should only occur upon contact of the skin contact area with the skin.

10 An adjustment wheel 51 is used for setting the puncturing depth. The torque transmission from the adjustment wheel, which is immobile in the axial direction, onto the axially movable connecting rod 19 may be provided by longitudinal teeth 52 of the connecting rod, which engage in corresponding internal teeth of the adjustment wheel 51 A housing bore 53, which in the case shown is positioned in the area of the elastic arms 40, is used for guiding the reference element positioning part 17a (thereby also a puncturing unit fixed in the holder 27). Room for the required elastic mobility of the arms 40 is provided by longitudinally running grooves (not shown). An axially mobile but rotationally fixed guide is ensured by a nonround cross-sectional design of the bore 53.

In the embodiment of the puncturing drive 4 shown in figure 4, a stroke adaption is again achieved by means of an elastic component 47. In this case, it comprises two springs, namely a drive spring 54 and a return stroke spring 55, which are each attached on one side to a housing-fixed bearing part 56 or 57 and act on the other side via a connection flange 58 to the connecting rod 19.

3 0 Figure 4 shows the rest state of springs 54 and 55. To cock the drive, the connecting rod 19 is moved to the rear (by means which are not shown) until a trigger element 59, which may comprise a latch 60 cooperating with the flange 58, catches. Due to the displacement of the connecting rod 19 during cocking longitudinal teeth 52, which are again provided at the end of the connecting rod 19 in this embodiment, engage in corresponding internal teeth of an adjustment wheel 51, so that the protruding distance of the needle tip of a puncturing unit connected to the holder 27 may be set by rotating the adjustment wheel 51.

After the trigger element 59 'is triggered, the connecting rod 19 is driven forward by the drive spring 54. Due to the elastic design of the drive the forward phase of the puncturing movement ends immediately after the contact instant. The longitudinal dimensions of the components are so designed that, in the entire variance range of the position of the skin c surface, the drive spring 54 is stretched beyond its rest position and the return stroke spring 55 is compressed beyond its rest position when the skin contact area of a puncturing unit fixed in the holder 27 hits the skin surface. As a result, the reversal point of the puncturing movement is reached immediately after the contact instant and subsequently the retraction phase is driven by the force of the return stroke spring 55, which predominates in this state.

Figure 5 shows four function positions (a) through (d) of a puncturing system comprising a stroke adaptor which is implemented by means of a friction coupling 95. In the case shown, it comprises the connecting rod 19 and pincers 96, whose arms 97 press against the connecting rod 19.
In this embodiment again the connecting rod 19 forms the connection to a holder 27 for a puncturing unit 1. Its design, including the needle element coupler, the reference element coupler, and the adjustment of the needle protruding. distance by rotating the connecting rod 19, corresponds to figures 1 'and 2.

The pincers 96 and the connecting rod 19 form two coupling elements of the friction coupling 95, which allow the transmission of a force in the 3 0 direction of the puncturingi movement. This force is designated as the "friction force F," and is determined by the friction conditions between the elements of the friction coupling, i.e., the pincers 96 and the connecting rod 19 here. If the force acting between the coupling elements 19, 96 exceeds the friction force Fõ they become movable in relation to one another in such a manner that the force transmission in the direction of the puncturing movement is disengaged. This is shown by the partial figures (a) through (c):
- During the forward phase of the puncturing movement (i.e., between the function positions shown in partial figures (a) and (b)), the friction force Fr is greater than the forces driving the movement in this phase, so that the relative position of the elements 19, 95 does not change.

Partial figure (b) shows the contact instant. The force needed for moving the needle element further forward rises significantly when the skin contact area of the puncturing depth reference element 10 contacts the skin. Thus the force exceeds the limiting value defined by the preset friction force Fr. Thus the elements of the friction coupling can move relative to each other which allows the required stroke adaption. In the example shown, the stroke is reduced by an amount dz which corresponds to the difference of the position of the pincers 96 between the skin contact instant (position (b)) and the maximum extension of the lancet drive 4 (position (c)).

During the retraction phase of the puncturing movement, the relative position of the two coupling elements first remains unchanged until the further rearward movement of the puncturing unit holder is stopped by a suitable movement limiter 98. During the further movement of the drive 4, there is a relative movement of the elements 96, 19 of the friction coupling 95 until they are again located in the starting position.
For this function, the friction force Fr must have a defined value. It must be dimensioned in such a manner that it is greater than the sum of those forces which arise during the puncturing movement before the contact instant. These are essentially the dynamic acceleration forces for moving 3 D the accelerated masses and the static puncture forces for penetrating into the skin. On the other hand the friction force Fr must be less than the maximum desired force with which the puncturing depth reference element 10 presses against the skin. These conditions can be fulfilled by means of known materials and production methods.

In the variants of the stroke adaptor shown in figures 3 through 5, the adaptation to the particular Z position of the skin surface is solely achieved by the elasticity of a component and/or by the friction coupling without specific control. If sufficiently comfortable piercing is not achieved thereby, an actively controlled stroke adaptor may be used, the active control being based on detection of the position of the skin surface, which may be performed mechanically or electronically, for example. Of course, the electronic variant also comprises optical-electronic detection -0 methods.

Regarding the control of the reversal point, the following basic principles can be distinguished:

a) The adaptation of the reversal point of the lancet movement may be performed before the start of the puncturing movement, particularly by shifting the puncturing drive in the longitudinal direction and thus adjusting the distance of the puncturing drive from the skin surface in such a manner that the reversal point of the puncturing movement is closely adapted to the actual position of the skin surface. Ideally, the reversal point of the puncturing movement is somewhat further forward than the position of the skin surface at the instant of skin contact. This small "stroke reserve" takes care of the elastic deformation of the skin surface upon piercing.
In this embodiment it is favorable to use a positively-controlled lancet drive, as was explained on the basis of the rotor drive of figure 3, for example. The distance between the starting position and reversal point of the puncturing movement, i.e., the absolute value of the stroke, remains unchanged- The stroke adaption is performed by 3 0 longitudinal displacement of the stroke movement.

This design principle allows especially precise stroke adaption, the longitudinal position of the reversal point being independent of the properties of the skin, particularly its elasticity.

b) The skin surface may be detected during the puncturing movement at or shortly before the contact instant. In this case the acceleration in the direction of the skin is interrupted and the return stroke is initiated as immediately as possible after the detection.

s Such a variant may be implemented with a relatively simple design by means of a sensing element at the front end of the puncturing unit. The sensing element cooperates with a control element (such as a latch), which is preferably also mechanical, interrupts the forward phase and initiates the retraction phase of the puncturing movement. Of course, electronic variants are also possible, in particular comprising an electronic sensor at the front end of the puncturing unit.
With this design principle, in contrast to a), the stroke of the puncturing movement is a function of the position of the skin is surface. The closer the skin surface is to the puncturing drive, the earlier the forward phase is interrupted and the retraction phase is initiated, i.e., the smaller is the stroke.

Figures 6 and 7 through 9 show two variants of puncturing units according to the present invention which are suitable for manual use, but may also be used as a component of a puncturing system. The longitudinal position of the puncturing depth reference element 10 in relation to the needle element 6 in the piercing direction (corresponding to the orientation of the needle) is changeable without a puncturing instrument and means are provided, by which the needle element 6 is fixed in a set position.

In the embodiment shown in figure 6, the body part 7 of the needle element 6 and the reference element body 12 have corresponding threads, which are adapted and arranged such that their relative longitudinal position, thus also the relative longitudinal position of the lancet tip 13 in relation to the skin contact area 11, is changeable by rotation relative to each other. To bring the needle tip 13 from the rest position shown within a sterile protector 14 into an operational position, in which it protrudes from the skin contact area 11, the body part 7 of the needle element 6 is rotated by means of a tool which engages a suitable gripping profile 62 of the body part 7. This may be performed manually.
Preferably, the puncturing unit shown in figure 6 is used with a puncturing instrument. In this case the setting of the puncturing depth can again be 5 performed manually before the insertion into the puncturing instrument or it can take place within the puncturing instrument.

In the variant shown in figure 7, a support profile 63 is provided at the rear end of the body part 7 of the needle element 6, which cooperates 10 with a corresponding multistep support profile 64 of a puncturing unit receptacle 65. A possible design of the support profile in cross-section, namely as circular sectors, is shown in figures 8 and 9.

In this case the puncturing depth reference element 10 is formed by a 1s cap 66 which encloses the front section of the body part 7 of the needle element. The cap 66 is fixed friction-locked on the body part 7. In the pre-operation status, an insertion aid 30 shown separately in figure 7 is seated over the needle 8_ It protects the needle tip 13 and is used for the purpose of inserting the puncturing ' unit I into the puncturing unit 20 receptacle 65 in a rotational position which corresponds to the desired puncturing depth- During insertion, the cap 66 is shifted forward in relation to the needle 8 when its lower edge 67 contacts the upper edge 68 of the puncturing unit receptacle 65. Thereby the protruding distance d of the needle tip .13 in relation to the skin contact area 11 is set. After 25 the insertion, the insertion aid 30 is twisted off, so that the needle 8 is exposed for use.

Numerous further variants of puncturing units according to the present invention are possible, which may also be used without a puncturing 3 o instrument. It is generally advantageous if the reference element body extends from the skin contact area towards the rear and encloses a body part of the needle element at least to such an extend that the longitudinal position of the needle element in relation to the puncturing depth reference element is fixed by contact between the reference element body and the body part of the needle element. The contact must be such that at least be friction-locking (as in figure 7) is achieved. Form-locking fixation of the needle element within the reference element body (as in figure 6) is especially advantageous for many intended uses.

Figures 10 to 13 show a puncturing unit which differs from the puncturing units previously shown primarily by the fact that the needle 8 of the needle element 6 has a capillary channel 70, having a lumen allowing body fluid to flow into a sample receiving area 71 of the needle element 6_ Thus the needle element 6 is a microsampler of the type explained above. Analysis means are located in the sample receiving area 71 (in the interior of the body part 7' of the needle element 6).

In this embodiment again, the setting of the puncturing depth is based on adjusting the distanced of the needle tip 13 from the skin contact area 11 is of a puncturing depth reference element 1,0 by means of positioning parts (16a, 17a), which are components of a needle element coupler (16) and a reference element coupler (17).

The needle element positioning part 16a is in this case implemented as a two-armed grip clamp 73. It has inwardly turned arms which are elastic and have projections 74 engaging in corresponding recesses 75 of the body part 7 of the needle element 6 when the needle element coupler 16 is closed. In the closed state of the needle element coupler 16, the longitudinal position of the needle element positioning part 16a is zs determined by the interaction of two stops 16b, 6b, which in the case shown are formed on one hand by an inner boundary face of the grip clamp 73 and on the other hand by the rear face of the needle element body 7. This needle element coupler, again, acts bidirectionally, i.e., it couples the positioning part 16a to the needle element 6 in both movement directions of the puncturing movement.

The reference element body 12 of the puncturing depth reference element 10 essentially comprises an open frame 77, on whose bottom side the skin contact area 11 is provided, and profiled parts 78 which run transversely to the longitudinal direction and enclose the needle element 6. The skin contact area surrounds an opening 69 for the needle 8 of the needle element 6.

This example shows that the reference element body does not have to be a closed component. Rather, an open structure is also suitable if it fulfills the functions required in the context of the present invention.
These include in particular, that the needle element 6 is connected to the reference element 10 in such a manner that a relative movement of both components in the longitudinal direction is possible for adjusting the io needle protruding distance d. In addition, the connection between the needle element 6 and the reference element 7 should allow a good guiding function in the longitudinal direction, so that movements of both components in spatial directions other then the piercing direction are prevented.
is The positioning part 17a of the reference element coupler 17 with its stop 17b is implemented at an axially guided but rotationally fixed bearing part 80. A corresponding stop 10b is formed by the rear face of the frame 77.
In this case it is a unidirectionally acting coupler, i.e., the interaction of 20 the stops 17b, 10b determines the relative longitudinal position of the puncturing depth reference element 10 only during the forward phase of the piercing movement (downward in figures 10 and 11), not during the retraction phase.

25 Similarly as in figures 1 through 4, the lancet drive 4 is connected via a connecting rod 19 to the puncturing unit holder 27 formed by the couplers 16, 17, the relative longitudinal position of the positioning parts 16, 17 being adjustable by rotation of the connecting rod 19 (to which the needle element positioning part 16a is attached) around its own axis within the :30 reference element positioning part 17a (of the bearing part 80 here).

The grip clamp 73 is rotatably mounted on the end of the connecting rod 19 and is guided in the puncturing instrument in such a manner that it remains in the gripping position shown in figure 10 independently of the 35 rotational position of the connecting rod 19. Electrical contacts may be provided in the area of the projections 74 of the gripping clamp 73 and the corresponding recesses 75, by means of which electrical measurements may be performed on a sample liquid located in the sample receiving area if the puncturing unit 6 is implemented as an s electrochemical microsampler_ Alternatively, a window 79 may be provided in the sample receiving area 71 to allow the required photometric measurement in case of a microsampler adapted for photometric analysis. These measurement principles are known-Therefore an explanation in more detail is not necessary.
io Figure 14 shows four usage phases (a) through (d) of a microsampler puncturing unit, whose design features correspond to figures 10 through 13:
- Partial figure (a) shows the pre-operation state, in which the needle 15 element 6 is fixed friction-locked in a specific longitudinal position in relation to the reference element 10. This fixing is achieved by nubs 62 on the reference element 10, which press against boundary surfaces of the body part 7 of the needle element 6.
Partial figure (b) shows the state at the reversal point of the 20 puncturing movement for a case of piercing with a relatively small needle protruding distance d, i.e., a relatively small piercing depth.
During the movement from the state (a) to the state (b), firstly the needle element coupler 16 (figures 10 and 11) is closed and the needle element 6 is pressed downward, the stops 16b, 6b abutting 25 against one another. At a later point in time during the forward phase, the contact between the stops 10b, 17b occurs, so that the reference element 10 is also moved in the direction toward the skin.
This movement sequence is an example showing the fact that the puncturing depth does not have to be set before the start of the 30 puncturing movement, but rather may also be set during its forward phase. The needle 8 penetrates into the skin and the forward phase of the puncturing movement ends when the skin contact area 11 abuts against the skin.

Partial figure (c) also shows the operational state at the reversal point of the puncturing movement, but with maximum needle protruding distanced, i.e., maximum puncturing depth.

When a sufficient sample quantity has flowed into the sample s receiving area 71 of the needle element 6, the retraction phase of the puncturing movement is initiated and the needle element is retracted into the reference element. The reference element is fixed by means which are not shown in the figures. The needle element 6 reaches the position shown in partial figure (d), in which the needle 8 io is retracted behind the skin contact area 11 to protect against a risk of injury. In this position, body part 7 of needle element 6 is located behind blocking projections 83, which are implemented in such a manner that the needle element 6 may not be moved back into the usable position (figures b or c). By providing blocking means of this 15 type on the reference element 12 and/or the needle element 6 the movement of the needle element 6 in relation to the reference element 10 is restricted, after the usage of the puncturing unit 1, in such a manner that further use of a used puncturing unit 1 is reliably prevented.
The course of the puncturing movement differs in the case of a microsampler (figures 10 through 14) from the typical puncturing movement of a lancet (figures 1 through 9). In the case of a lancet, the retraction phase of the puncturing movement occurs immediately after the reversal point and the puncturing movement as a whole should take place as rapidly as possible. In contrast, in the case of a microsampler, the movement of the puncturing unit during the retraction phase after the reversal point is interrupted or slowed for the time span needed for suctioning the body fluid. A corresponding position-time diagram is shown in figure 15. It shows a steep rise, which corresponds to a rapid movement in the piercing direction during the forward phase V. After reaching a maximum M, which corresponds to the reversal point of the puncturing movement, follows in the preferred embodiment shown, a first and rapid retraction movement R1, which then passes over into a slow retraction movement R2. The section of the retraction phase identified by R1 serves for forming a small open space within the skin tissue in the area in front of the needle tip in which space sample liquid collects.
During the subsequent section R2, blood flows through the capillary channel of the microsampler into its sample receiving area. When this 5 procedure is terminated, section R3 of the retraction phase follows, in which the needle is pulled out of the skin tissue.

A movement sequence of this type which is suitable for a microsampler may be implemented in various ways. A mechanical spring drive is io particularly suitable for the forward phase V and the first section of the retraction phase R1, while the relatively slow and controlled movement during sections R2 and R3 is advantageously driven by an electric motor.
Figures 16 and 17 illustrate that the present invention may also be used-is in puncturing systems in which a plurality of puncturing units are together provided in a magazine and are transported in sequence into a puncture position within the puncturing instrument. A device suitable for this purpose, which is known from US Patent 6,616,616, is shown in figure 16. Lancet-shaped puncturing units 1 are located in a magazine strip 85 20 made of plastic, in which they are held in such a manner that they are axially movable and guided. On their rear end, they have a coupling cylinder 86. it is used for coupling a lancet located in a puncture position 87. to a coupling mechanism 3, which forms the connection to a puncturing drive (not shown).
Figure 17 illustrates alterations by which the present invention may be implemented in a puncturing system including puncturing units confected in a magazine. The puncturing movement generated by a puncturing drive (not shown) is transmitted by means of a connecting rod 19, which 50 makes a puncturing movement 24 in relation to the magazine strip 85. In this embodiment the coupling cylinder 86 forms the body part 7 of the needle element 6. The connecting rod 19 acts on a bearing part 88, into which a set screw 89 is screwed- The bearing part 88 and a puncturing depth reference element 10 having a skin contact area 11 are guided in 3s the direction of the puncturing movement by means of guide rods 90, 91.

In this construction, the positioning part 16a of the needle element coupler 16 is formed by the bearing part 88. A stop 16b is formed by the bottom surface of a recess 992 provided in the bearing part 88, which receives the coupling cylinder. It cooperates with a corresponding stop 6b, which is formed in this case by the rear end of the needle 8 of the needle element 6_ In this embodiment the reference element coupler 17 acts to unidirectionally. Its positioning part 17a is formed by the set screw 89, whose front face acts as a stop 17b, which cooperates with a corresponding stop 10b of the reference element 10.

When, in the forward phase of the puncturing movement, the connecting rod 19 is moved forward (upward in figure 17), firstly the needle element 6 is moved in the piercing direction until the needle tip 13 projects out of the opening 69 surrounded by the skin contact area 11. The resulting protruding distance is determined by the longitudinal position of the set screw 89, i.e., the stop 17b implemented thereon, in relation to the stop lob of the reference element. Upon contact of these two stops, the reference element is synchronously transported against the force of a retraction spring 93 together with the needle element 6 until the piercing occurs. The depth of the piercing is determined by the protruding distance of the needle tip 13 in relation to the skin contact area 11.
In this embodiment the components 88, 89 and 10 are components of the magazine, which are only provided once for each magazine.
Alternatively, they may also be implemented as a component of the puncturing instrument. In any case, it is advantageous if, in a puncturing system according to the present invention including puncturing units located in a magazine, only one (shared) puncturing depth reference element is provided for all puncturing units of the magazine. A transport movement occurs between the puncturing steps, whereby a new needle element 6 is brought into the position (shown in figure 17), in which it is moved during at least a part of the puncturing movement together with the reference element to ensure the desired puncturing depth.

The present invention may be used in connection with different magazine designs. In particular these include drum magazines, as are described, for example, in cited US 2004/0260325.

In the puncturing system shown in figures 18 and 19, the design of the puncturing unit 1 and its connection to the puncturing drive 4 largely correspond to figures 1 and 2. The puncturing unit 1 comprises a needle element 6 including a needle 8 and a needle element body 7 enclosing the needle and made of plastic, as well as a puncturing depth reference element 10 comprising a reference element body 12, sleeve-shaped in.
this case, and a skin contact area 11.
The connection to the lancet drive 4 is provided by a coupling mechanism 3, which comprises a needle element coupler 16 and a reference element coupler 17. Corresponding to figures 1 and 2, the positioning part 16a of the needle element coupler 16 is formed by the head 18 of a connecting rod 19, which engages in a corresponding receptacle 31 of the needle element body 7_ The reference element coupler is in this case again formed by means of a catch coupler comprising catch hook 25 and catch profile 26, which are implemented on puncturing depth reference element 10 and reference element holder 100, respectively. The latter is movable in the longitudinal direction on the connecting rod 19.

The puncturing system of figures 18 and 19 has (corresponding in this respect to figure 4) a so-called "ballistic" puncturing drive 4, in which the puncturing movement is not "positively controlled" as defined above. In a ballistic puncturing drive, the puncturing movement is determined, at least in its section close to the reversal point, preferably on the entire movement path, only by the accelerating force of one or more drive springs, the mass inertia of the components accelerated thereby, and the movement of controlling or limiting stops (furthermore, of course. by the friction between moving components).

in the case shown, a helical spring is used as the drive spring 54, which is shown in the compressed state in the figures. It is coupled to a connecting rod 19; which is accelerated by the drive spring 54 in the piercing direction after actuation of a trigger element 59. In the embodiment shown, the trigger element 59 is a bolt 123, which locks the connecting rod 19 in the retention position shown. To trigger the puncturing movement, the bolt 123 is retracted in such a manner that the connecting rod 19 can be accelerated by the drive spring 54.

The reference element coupler 17 is closed upon insertion of the puncturing unit 1. The needle element coupler 16, in contrast, is only is closed after the actuation of the trigger element during the forward movement of the connecting rod 19. Thereafter both the movement of the needle element 6 and the movement of the puncturing depth reference element 10 exactly follow the movement of the corresponding positioning part 16a. 17a, i.e., of the connecting rod 19 and the reference element holder 100.

During the further forward phase, the connecting rod 19 moves forward until its stop face 101 contacts a corresponding stop face 125 of an adjustment device 126, which is provided at the rear end of the reference element holder 100. The stop face 125 is located on the head of an adjustment screw 127, which is screwed onto a thread 128 running in the piercing direction. By rotating the adjustment screw 127, the longitudinal position of the stop face 125 in relation to the reference element 10 (and thus in relation to the skin contact area 11) may be adjusted.

In the preferred embodiment shown, the puncturing drive 4 is directly coupled only to the needle element 6. The reference element 10 is coupled via a co-transport device to the needle element 6 and thus indirectly to the puncturing drive 4, the con-transport device acting in the forward phase of the puncturing movement. The components of the co-transport device, designated as a whole by 103, are the two stops 101 and 125, which abut against one another during the further forward phase up to the reversal point of the puncturing movement in such a manner that their relative distance defines the longitudinal position of the s needle tip 13 in relation to the contact area 11 of the puncturing depth reference element 10. and thus the puncturing depth. The stops 101, 125 are therefore designated "puncturing depth limiting stops"_ At the reversal point of the puncturing movement, the drive spring 54 is io stretched so that the connecting rod 19 is retracted again and thus the retraction phase of the puncturing movement starts. In the case shown, the spring force of the drive spring 54 is used for accelerating the puncturing unit both during the forward phase and also during the retraction phase of the puncturing movement.
i5 For the preferred function of the puncturing system shown, it is also important that the reference element 10 rests, by means of a reference base part 146, on a reference element bearing 105 during a part of the forward phase and especially preferably (as will be explained) also during 20 a part of the retraction phase. A reference base part is understood as a functional element which is connected directly or indirectly to the reference element 10 and limits, in cooperation with the reference element bearing, its movement path to the rear in a defined position. In the design shown, it is formed by a shoulder formed on a needle element 25 retraction limiter 138, which is connected to the reference element holder 100 and whose function will be explained in more detail.

In the embodiment shown here, the position of the reference element bearing 105 is selected in consideration of the dimensions of the 30 remaining components in such a manner that the contact of the reference element stops 101, 125 first occurs shortly before the reversal point of the puncturing movement, so that the reference element holder 100 lifts off only by a short distance from the reference element bearing 105 until reaching the reversal point- Even if the reference element 10 can move 35 freely in the piercing direction (i.e., does not hit a body part located in its movement path), the maximum distance dh shown in figure 21B, by which the reference base part 146 lifts off of the reference element bearing 105, is at most 5 mrn, preferably at most 3.5 mm, and especially preferably at most 2 mm.

At the beginning of the retraction phase, the reference element 10 is moved rearwardly together with the needle element 6 by the short distance dh by which the reference base part 146 was lifted off of the reference element bearing 105_ This rearward movement is caused by 10 the elasticity of a skin surface to which the skin contact area 11 abuts and, in addition, by the rearward movement of the connecting rod 19 and the needle element 6, the friction between these elements and the puncturing depth reference element 10 or the reference element holder 100 causing sufficient force transmission.
~s A further rearward movement of the reference element holder 100 and thus the reference element 10 is stopped by the reference element bearing 105, while the connecting rod 19 and thus the needle element 6 are drawn further rearwardly by the force of the spring 54, until the 20 movement is stopped by a stop element 137 of the mentioned needle element retraction limiter 1313. In the case shown, the needle element retraction limiter 138 comprises a spring element 139 in the form of a spring arm, which carries the stop element 137, implemented as a latch, on its free end. The latch has a beveled sliding face 140, which, during 25 the forward phase of the puncturing movement, slides past a corresponding sliding face 141, which is formed on a catch projection 142 provided at the connecting rod 19. During this sliding, the spring arm 139 of the needle element retraction limiter 138 yields elastically to the side. As soon as the catch projection 142 has passed the stop element 3 o 137, it returns back into its original position due to the spring force of the spring arm 139. In this position it stops the connecting rod 19 and thus the needle element 6, a stop face 143 of the catch projection 142 of the connecting rod 19 hitting a stop face 144 of the stop element 137.

The needle element retraction limiter 138 may also have a different design. In principle, any element by which the retraction movement of the puncturing unit 6 can be stopped in a defined longitudinal position is suitable. This longitudinal position is preferably selected in relation to the s longitudinal position of the skin contact area 11 provided by the reference element bearing 105 in such a manner that the tip 13 of the needle element 8 projects by a defined residual puncturing depth from the plane of the skin contact area 11.

1 o Figures 18 and 19 illustrate that greatly varying coupler types may be used as a component of the coupling mechanism 3 between the puncturing drive 4 and the puncturing unit 1. The needle element coupler 18 couples the puncturing drive 4 to the needle element 6 during the forward phase of the puncturing movement and then forms a is bidirectionally acting fixed connection between these elements. The connection between the puncturing drive 4 and the reference element 6 is provided indirectly via the reference element holder 100. This holder is fixedly connected to the reference element 10, upon insertion of the puncturing unit 1, by means of bidirectionally acting reference element 20 coupler 17. In addition, the reference element holder 100 is a component of the co-transport device 103, which includes two pairs of stops 125, 101 and 143, 144, which each form a coupler acting in one direction (unidirectional). These couplers are implemented in such a manner that the connecting rod 19 and with it the needle element 6 is movable 25 relative to the reference element over a distance Ad between the stops 125 and 144. Ad preferably corresponds to the difference between a maximum piercing depth dm and a residual piercing depth dr, as will be explained in more detail hereafter.

30 The puncturing movement shown in figure 20 in the form of a position-time diagram ("puncturing profile") may be implemented by the construction of figures 18 and 19. It is suitable preferably for microsampler puncturing systems, in general for puncturing systems whose needle element has a capillary channel to receive a sample. figure 35 21 shows four operational positions of a puncturing system largely corresponding to the puncturing system of figures 18 and 19, some elements have been simplified with respect to details which are not significant for the functions explained here. The instants corresponding to the operational positions A through D are marked in figure 20 by these letters-Figure 20 shows the position-time curve of the piercing depth d of the needle element during a forward phase V and a retraction phase R, the retraction phase R comprising a first retraction section R1, a collection section S, and a second retraction section R2. The time axis has a varying scale. In practice the section of the movement identified by T, is executed within a few milliseconds, while the movement section identified by T2 (braking before the collection section) lasts several hundred milliseconds and the collecting section (T3) can last several seconds.
is At the end of the forward phase V (operational position B), the puncturing element reaches a maximum piercing depth dm, which is typically 0.8 mm to 2.3 mm depending on the setting of the puncturing instrument.
This is followed by the first retraction section R1, in which the puncturing :o element is partially retracted by a retraction segment Ad. At the end the element is braked so that it projects into the skin at a predefined residual puncturing depth dr of 0.5 mm, for example (operational position C).
Finally, a second retraction section R2 follows (operational position D), in which the needle 8 of the needle element 6 is pulled completely out of 25 the skin.

In the construction shown in figures 19, 20, and 21, the second retraction section. at the end of the collection phase is initiated by drawing the blocking bolt 145 from the engaged position shown in figures 19 and 21A
30 through 21 C into a retracted position shown in figure 210. Thereafter the retraction limiter 138 is moved by the drive spring 54 rearwardly together with the connecting rod 19. The retraction phase is thus terminated and the needle 8 of the needle element 6 is completely removed from the skin.

If one compares the puncturing profiles shown in figures 15 and 20, a first difference is that the residual puncturing depth dr during the collection section S of the retraction phase practically does not change.
Rather - in the constructicn shown in figures 18 through 21 due to the s interaction of the reference element bearing 105 and the needle element retraction limiter 138 - it has a predefined constant value. It is especially significant that the maximum puncturing depth dm can be set independently of the residual puncturing depth dr. In this regard, the puncturing system of figures 18 through 21 differs from the previously io described puncturing systems, in which the setting of the puncturing depth simultaneously has an effect on the entire puncturing movement and therefore the residual puncturing depth dr, at which the sample is received in a microsampler, unavoidably changes when the maximum puncturing depth dm is adjusted.
is The inventors have found that it is very advantageous for the quality of obtaining samples and for the pain sensation during usage of microsampler puncturing systems if the residual puncturing depth, i.e. the puncturing depth by which the needle of the needle element projects into 20 the skin during the collection of the sample, is approximately constant independently of the set maximum puncturing depth. Small variations of the residual puncturing depth or a slow movement of the needle element during the uptake of the sample are acceptable. It is, however, necessary that the maximum puncturing depth dm can be adjusted independently of 25 the average over time of the residual puncturing depth during the uptake of the sample.

A further exemplary embodiment of a puncturing system, by means of which a puncturing profile having the special features explained on the o basis of figure 20 may be implemented, is shown in figure 22 in a side view, in figure 23 in cross-section, and in figure 24 in a perspective oblique view-The design of the puncturing unit I and the couplers 16 and 17 35 corresponds to those of figures 18 and 19. These elements, which are identified here by the same reference numerals, and their function are therefore not described again.

The puncturing drive 4 differs significantly from figures 18 and 19. It is a s rotor drive having stroke adaption, as is explained in more detail hereafter, The puncturing drive 4 of the puncturing instrument 2 includes a drive spring 201, a cocking rotor 202 for cocking the drive spring, and a drive io rotor 203 driven by the drive spring 201_ The rotational movement of the drive rotor 203 is converted into the puncturing movement of the needle element 6 by means of a control unit in the form of a cam controller. A
needle element control curve 205 is implemented as a groove in the drive rotor 203 and is traveled by a needle element control curve traveler 206 15 (in the form of a pin engaging in the control curve 205), which is connected to a connecting rod 19, to which the needle element 6 is coupled.

The movement of the puncturing depth reference element 10 is also 20 controlled by a cam controller comprising a reference control curve 212 and a reference control curve traveler 213. The reference control curve 212 is also implemented as a groove in the drive rotor 203. A control curve traveler 213, which is connected to the reference element holder 100, engages the control curve 212-To set the puncturing depth, the distance of the two control curves 205 and 212 is adjustable by means of an adjustment device 214 in the form of an adjustable axial mount. The two control curves 205 and 212 are located on a first part 203a of the drive rotor 203 and on a second part 203b of the drive rotor 203, respectively. The distance between the first part 203a and the second part 203b of the drive rotor 203 can be varied by means of the adjustment device 214.

During usage, the puncturing instrument is pressed against a skin as surface of the user by means of a housing skin contact area 33, which is only schematically shown in figure 21 and encloses a housing opening 35. The distance of the reference element 10 from the skin surface is subsequently determined for the purpose of (active) stroke adaption_ For this purpose, a first slide 221 displaceable in the piercing direction is s moved by an electric motor 220 toward the skin surface. The drive 4, including the needle element positioning part 16a formed by the connecting rod 19 and the reference element positioning part 17a formed by the reference element.holder 100, is mounted on the first slide 221.
Slide 221 is moved forward until the reference element 10 contacts the zo skin. Contact may be detected electronically, for example by an inductive or capacitive measurement. Thereafter, the slide 221 is retracted again until there is a defined distance to the skin surface.

After a puncturing movement is triggered, the needle element positioning 15 part 16a and the reference: element positioning part 17a are moved forward by a rising flank of the corresponding control curves 205, 212 during the forward phase of the puncturing movement. While the needle 8 of needle element 6 penetrates into the skin surface, the skin contact area 11 of the reference element 10 abuts against the skin, so that a 20 reference point for a precise piercing depth is defined.

To compensate for the Z variance, a stroke adaptor 38 is again provided in this embodiment. In this case even two stroke adaptor constructions are used in combination:
25 - Firstly active stroke adaption is implemented comprising detection of the position of the skin surface before a puncturing movement is triggered and subsequent adaption of the puncturing movement to the previously detected position (thereby shifting the entire stroke path). This form of active stroke adaption is advantageous not only s 0 in the embodiment shown, but rather also in other constructive implementations.

In addition, passive stroke adaption is provided, which is implemented here by mounting the first slide 221 such that it is displaceable in the longitudinal direction on a second slide 222, 35 which may be shifted backwards against the force of a contact pressure control spring 223. By these means a maximum contact pressure is defined, which may act on the skin surface via the reference element 10. This additional passive stroke adaption is facultative.
After reaching the reversal point of the puncturing movement, the needle element positioning part 16a and the reference element positioning part 17a are retracted. The carp controller 205, 206 acting on the needle element positioning part has the special feature that the needle element io control curve traveler 206 disengages during the retraction movement from its engagement in the corresponding control curve 205. This means that, deviating from the usual design, the control curve traveler is not positively controlled on the entire control curve in such a manner that each position of the control curve traveler on the control curve is corresponds to a defined longitudinal position of the rider and thus the element controlled thereby (needle element or reference element) in the piercing direction. Rather, the longitudinal position of the control curve traveler and thus the controlled element is at most delimited in one spatial direction (in the piercing direction or opposite to the piercing 20 direction) when the engagement of the control curve is disengaged, but is free at least in the opposite spatial direction. This is achieved in the embodiment shown by making the groove forming the control curve 205 wider so that the control curve traveler 206 is no longer guided there. The needle element positioning part 16a (and thus the needle element) is 25 therefore during the retraction phase not actively retracted by the needle element control curve traveler 206.

The retraction movement of the needle element positioning part 16a is instead caused by means of a restoring spring 225_ It couples the needle 3 o element positioning part 16a to the first slide 221 and thus also to the drive 4. During the retraction phase, the needle element positioning part 16a is therefore moved rearwardly by the restoring spring 225 relative to the drive until a second control curve traveler 226 connected thereto engages a further control curve 227, which is formed at the second part 35 203b of the drive rotor 203_ The further control curve 227 thus forms a retraction limmiter, by means of which the movement of the needle element 6 is stopped at the end of the first retraction section R1. This ensures a defined position of the needle element positioning part 16a in relation to the reference element positioning part 17a, in which the tip 13 s of the needle 8 projects at a predefined residual puncturing depth from the skin contact area 11 of the puncturing depth reference element 10.
After termination of the co'lection section S, the needle element 6 is pulled completely out of the skin by retracting the first slide 221 by means of the electric motor 220.
io The embodiments shown in figures 17, 18/19 and 22 to 24 show as examples that the puncturing depth reference element 10 does not have to be moved together with the needle element 6 during the entire forward phase (as in figures 1 and 2, for example). Rather, it may be 5-5 advantageous if the puncturing depth reference element 10 is only moved together (i.e., simultaneously, not necessarily equally fast) with the needle element in the part of the forward phase immediately preceding the reversal point. The length of the stroke (path segment in the piercing direction), by which the puncturing depth reference element 20 10 is moved together with the needle element 6 until reaching the reversal point, is preferably at most 5 mm, more preferably at most 3.5 mm, and especially preferably at most 2 mm. In the construction shown in figures 17 and 18/19, this is achieved by the fact that the puncturing depth reference element 10 rests in a rest position on a reference 25 element bearing and is co-transported with the movement of the needle element starting from this rest position, shortly before the needle element reaches the reversal point. Other constructions are possible, however, as shown in figures 22 to 24.

3 o Furthermore, it is advantageous if the time needed for the partial section of the puncturing movement, during which the puncturing depth reference element is moved together with the needle element during the forward phase (i.e., until reaching the reversal point), is very short- This time is preferably at most 100 ms, more preferably at most 50 ms, and 35 especially preferably at most 10 ms.

It has been established in the context of the present invention that the above described measures, which may be used individually or in combination with one another, allow a precise control of the puncturing depth. In addition, with such a short pressure application onto the skin the viscoelastic properties of the skin do not cause a substantial deterioration of the precise definition of the residual puncturing depth by a deformation of the skin. It is furthermore advantageous if, in a puncturing profile of the type shown in figure 20, the first retraction section R1, between reaching the reversal point (maximum puncturing depth) and beginning the collection section, lasts at most 2 seconds, preferably at most 1 second, and especially preferably at most 0.5 seconds.

In the puncturing system shown in figure 25, the design of the puncturing unit and the couplers 16 and 17 essentially corresponds to figures 18/19 and 22 through 24. These elements are again designated by the same reference numerals and are not described again.

Also corresponding to figures 18 and 19, the reference element positioning part 17a is formed by a reference element 100, which is movable in the longitudinal direction in the housing (not shown) and rests, in the starting position of the puncturing movement shown, on a reference element bearing 105. The reference element 100 and a puncturing unit I connected thereto via the reference element coupler 17 are guided in the longitudinal direction in 'a housing part 301. The remaining housing is not shown. However, a housing skin contact area is also provided in this puncturing system, as is shown as an example in figures 2c and 22.
A further feature which is common figures 18 and 19 is that a ballistic puncturing drive 4 is used. However, in the case shown it operates according to the "hammer-anvil principle", i.e., a component identified as a hammer 302 in figure 25 (only shown symbolically), is moved rapidly in the direction toward an anvil 303, which in turn is operationally linked via a coupling mechanism 3 to the puncturing unit 1.

In this embodiment, the reference element coupler 17 is again closed upon insertion of the puncturing unit 1. The reference element holder 100 forms a holder 27 for receiving a disposable puncturing unit 1. The needle element coupler 16 is closed only when the connecting rod 19 connected to the anvil 303 is moved forward. A further similarity with figures 18 and 19 is that a co-transport device 103 is again provided io here, which includes the two corresponding stops 101 and 125. The puncturing drive 4 is again directly coupled only to the needle element 6 here, while the reference element 10 is coupled to the needle element 6 and thus indirectly to the puncturing drive 4 via the co-transport device 103 acting in the forward phase of the puncturing movement.
3.5 Deviating from figures 18 and 19, the puncturing depth adjustment of figure 25 is implemented by a longitudinal displacement of a puncturing depth limit stop connected to the needle element 6 (not to the reference element 10)_ In the embodiment shown, a puncturing depth adjustment 21) ring 305 is rotatable on a thread 306 of the connecting rod 19 and may thus be adjusted in its longitudinal position in relation to the needle element 6_ The puncturing depth adjustment ring 305 is used for mounting a stop ring 307 elastically displaceable in the longitudinal direction on the connecting rod 19, the elasticity being provided by a 25 metallic contact pressure spring 308.

When the anvil 303 is moved forward (to the left in figure 25) as a result of the impact of the hammer 302, the bidirectionally acting needle element coupler 16 closes. When the stop faces 101 and 125 are in 3 o contact, they form a unidirectionally acting coupler, which provides, with the elasticity caused by the spring, a connection between the connecting rod 19 (and thus the drive 4) and the reference element 10. The longitudinal dimensions of the components are so adapted to one another that in the subsequent movement phase up to the contact instant 35 (incidence of the skin contact area of the puncturing depth reference element on the skin surface), the distance between the skin contact area 11 and the tip 13 of the needle element 6 is less than the desired (predefined) value of the puncturing depth. Preferably the tip 13 of the needle element 6 is in this movement phase even located behind the skin 5 contact area in the piercing direction, so that the piercing into the skin occurs only after the contact instant.

Upon contacting the skin, the reference element 10 is stopped. The elasticity of the contact pressure spring 308 (more generally stated the IQ elasticity of the coupling between the puncturing depth reference element 10 and the puncturing drive 4) ensures that the skin contact area 11 is pressed against the skin at a pressure corresponding to the elasticity of the spring. This causes tensioning of the skin, while a further movement forward of the needle element is possible until the reversal point of the 15 puncturing movement is reached.

In the embodiment shown the required limiting of the movement of the needle element is achieved by the fact that the relative movement between the puncturing depth adjustment ring 306 and the stop ring 307 20 is stopped when stops 309 and 310 provided on these elements abut one another. The maximum movement path of the needle element 6 in relation to the reference element 10 is thus limited and the needle element 6 has at the reversal point of the puncturing movement a defined longitudinal position in the piercing direction in relation to the puncturing 25 depth reference element 10. Accordingly, the stops 309 and 310 act as puncturing depth limiting stops. The stops 309 and 310 as well as the stops 101 and 125 form two unidirectionally acting couplers and abut against one another at the reversal point of the puncturing movement in such a manner that their relative distances define the puncturing depth.
The retraction phase of the puncturing movement is driven by a retraction spring 311, which rests on one side against a housing-fixed bearing part 312 and on the other side against the anvil 303. First the needle element 6 is drawn backwards so that the needle tip 13 is retracted behind the skin contact area 11 and the catch hook 25 again enters the catch profile 26, thereby fixing the'longitudinal position of the needle element 6 in the puncturing depth reference element 10. The further rearward movement of the connecting rod 19 acts on the entire puncturing unit 1 until it is stopped by the contact of the reference element holder 100 with the s reference element bearing 105.

In the final position shown, the puncturing depth reference element 10 is coupled to the puncturing drive 4 via a pair of corresponding stops 143, 144. In figure 25 the co-transport device 103 again acts bidirectionally, on 2,o one side by the stops 101, 125, 309, 310 and on the other side by the stops 143 and 144. Deviating from figures 18 and 19, however, this design is not provided to ensure a defined residual puncturing depth, but rather to fix the reference element holder 100 and, with it the reference element, in the shown position due to the operation of the stops 143, 144 is in the retraction phase. The puncturing unit 1 may be pushed out and ejected as a whole from the holder 100 by means of an ejector (not shown here).

Practical testing of the embodiment of figure 25 has shown that a very 20 well reproducible puncturing depth and an extremely low pain sensation are achieved therewith- According to the current findings of the inventors, this is to be attributed, inter cilia, to the fact that the skin contact area of the puncturing depth reference element exerts a pressure on the skin surface which is sufficient to tension the skin when the piercing occurs.
2s Therefore, the puncturing drive and the coupling mechanism should be implemented in such a manner that, at the skin contact instant (instant of the contact of the skin contact area 11 with the skin surface), the tip 13 of the needle element 8 does not project at all, or projects only so slightly over the skin contact area that the pressure of the skin contact area is 30 already effective at the instant at which the needle tip enters into the skin.
In the context of the present invention it has been established that the longitudinal position of the needle element 8 and the skin contact area 11 as well as the pressure exerted by the skin contact area 11 (during the 35 following partial section of the forward phase) on the skin surface may be experimentally optimized in such a manner that the negative influence which skin deformation caused by the piercing of the needle element into the skin has on the reproducibility of the puncturing depth, may be decisively reduced. Experiments have shown that this is possible so well s that the skin deformation no longer has practically important influence on the puncturing depth. This statement is supported by the fact that the actual depth of the puncture into the skin corresponds very well with the set puncturing depth of the device (distance between the tip 13 and the skin contact area 11). It has been established that without the measures io described here, the actual puncturing depth into the skin was more than 0.3 mm smaller than the puncturing depth set on the device.

In this context also the size of the skin contact area plays a role. Its diameter should be at least 1.5 mm, but preferably not more than 6 mm.
is The skin contact area 11 must be designed as soft-edged as possible. In particular, it would be disadvantageous if a sharp edge was present in the region of the skin contact area 11 after removal of the insertion aid 30, as is unavoidable when using the breakiine design common in this context (having a weak line made of thin plastic). in the case shown, the 20 connection between the insertion aid 30 and the puncturing depth reference element 10 is therefore provided by a connection profile 30a made of soft, highly-elastic plastic. However, other constructions are also possible, if it is ensured that the skin contact area is free of broken edges after removal of the insertion aid 30. Preferably the skin contact area it is 25 convexly curved in the vicinity of the needle element exit opening.

The effect of skin tensioning and the excellent reproducibility of the puncturing depth is a function of a plurality of factors. Therefore no generally applicable statements can be made about the parameters 30 which are optimal in this regard. In general, however, the pressure by which the skin contact area 11 of the puncturing depth reference element is pressed against the skin surface in the last partial section of the forward phase should be so high that the skin deformation caused by the piercing of the needle element into the skin ("denting") has practically no 3s interfering effect on the reproducibility of the puncturing depth. This pressure should be at least 1 N/cm2, preferably at least 3 N/cm2, and especially preferably at least 5 N/cm2. In the context of the present invention, it has been established that the internal pressure in the tissue resulting from this relatively strong contact pressure allows to minimize s negative influences which the denting of the skin, upon piercing of the needle into the skin surface. normally has whereby a very good reproducibility of the puncturing depth is achieved. In addition, an extremely low pain sensation results.

io It is to be assumed that the indirect coupling of the puncturing depth reference element 10 to the drive 4 by means of the co-transport device 103 and/or the elastic coupling and pressure control caused by the metal contact pressure spring 308 also provides a significant contribution to the outstanding function of the described puncturing system. The spring is zs installed pre-tensioned in such a manner that it acts, already in its maximum expanded state, with the desired minimum force. The force variation per unit of length (spring constant) is preferably at most 0.1 N/mm.

20 The co-transport device (in particular an elastic co-transport device) can also be implemented inside the puncturing unit itself. In this case corresponding stops can be provided on the elements movable in relation to one another (needle element and puncturing depth reference element). In the case of an elastic co-transport device, a spring may be 25 provided which is supported on one side on the needle element and on the other side on the puncturing depth reference element.

The puncturing system shown in figures 26 to 30 is distinguished above all by the fact that the needle elements 6, which are preferably 30 implemented here as simple. metallic, needle-shaped lancets 330, are combined here to form a needle element strip 331 (figure 26). The needle element strip 331 has a carrier film 328, on which the rear ends (facing away from the tip 13) of each of the lancets 330 are fixed by adhesive. A
cover film 329 covers the lancets and thus seals them hygienically. The assembly (confecting) of lancets in the form of strips is generally known, for example, from German Patent 28 03 345 and EP 1 360 935 Al _ In connection with the present invention, it is important that the carrier s film 328 and the cover film, 329 of the needle element strip 331 are very thin. The thickness of the carrier film 328 is preferably at most 100 ,um, especially preferably at most 50 pm, and even more preferably at most 30 um. The thickness of the cover film 329 should be at most 50 ,um, preferably at most 25 pm, and more preferably at most 15 pm_ 2.0 In the context of the present invention, the needle element strip 331 is not only used to allow sterile packaging of a plurality of needle elements and for supplying them for use in a cost-effective manner. Rather the carrier film 328 also forms a hygienic topcoat for the skin contact area 15 during the piercing. Thus it is a component of the puncturing depth reference element. A suitable construction of the puncturing system is shown in four operational positions in figures 27 to 30.

The needle element strip 331 is transported by a transport device (not z0 shown) in such a manner step-by-step that one lancet 330 at a time is located at a puncture station 332 in front of a reference element base part 333 (figure 28). A strip retainer 334 is a component of a puncture preparation device identified as a whole by 335, by which a needle element 6 located at the puncture station 332 is brought into a puncture 25 position in which its tip 13 is exposed and oriented in the piercing direction, while the carrier film 328 covers the reference element base part 333 in the surroundings of the needle tip 13 (figure 29). In the embodiment shown, the strip retainer 334 is L-shaped in a plane parallel to the piercing direction and it is shifted over the needle element strip 331 30 in such a manner that the strip is bent at a right angle. Thereafter a part of the strip covers the front edge of the reference element base part 333 (on the left in the figure) and forms the skin contact area 11 there. This Is an example of an embodiment of the present invention, in which not the entire piercing depth reference element 10 is a single-use (disposable) 35 item, but rather only the element which has the skin contact area.

A lancet gripper 338, which is moved against the lancet from the rear (from right to left in the figures) is used to move one lancet at a time, a recess 339 of the lancet gripper enclosing the rear end of the lancet s (figure 30). The movement path of the lancet gripper 338 in relation to the reference element base part 333 is limited by a puncturing depth adjusting screw 340. When the front end of the puncturing depth adjusting screw 340 abuts against the reference element base part 333, further movement of the lancet gripper 338 forward (to the left in the zo figures), causes a corresponding movement of the reference element' base part 333 and thus also the carrier film 328, with the skin contact area (i.e.. the reference element formed as a whole by the carrier film 328 and the base part), together with the lancet 330. The needle protruding distance d shown in figure 298 defines the puncturing depth.
is The piercing into a finger 342 shown in figure 30A is performed by the forward movement.

During practical testing of this embodiment, it has been established that surprisingly a very well reproducible puncturing depth result if very thin 20 films are used (having the preferred thicknesses specified above), even if the carrier film 328 or residues of the cover film 329 do not form a smooth topcoat in the region of the skin contact area 11, but rather wrinkle, for example. Therefore, in this embodiment the advantages of the present invention, may ideally be combined with the advantages of a 25 needle element strip. This is in particular true if the strip not only carries needle elements (lancets), but also alternating test elements and the system is implemented as an integrated system which not only performs blood withdrawal, but rather also analysis, A combined analysis element strip allows the simple implementation of transport functions necessary in 30 such integrated systems, while simultaneously avoiding hygienic problems by using the carrier strip as a component of the reference element in the region of the skin contact area. The test elements are favorably produced separately because of the sensitivity of the reagents contained therein and are attached to the carrier film 328 by adhesive.

Figures 31 to 33 show those parts of a further puncturing system which are important for its function. In this case the coupling mechanism 3, by which a needle element 6 and a reference element 10 are connected via a connecting rod 19 to a drive (not shown), is implemented in an s especially simple and space-saving way. In the case shown the needle element 6 only comprises a metal needle 8. For the coupling mechanism shown, it is characteristic that the puncturing depth reference element 10 simultaneously forms a gripper 350 which encloses the needle element 6 like pincers and thus fixes it. In the embodiment shown, gripper arms 351 of the gripper 350 are actuated by a closing mechanism 352, which does not have to be explained in more detail, because suitable mechanical principles are known (for example, for holding leads in a mechanical pencil). It is decisive.that the gripper element is implemented in such a manner that it may be pushed over the needle element 6 in the open is state (figure 31) and the gripper arms 351 may subsequently be closed, so that they fix the needle element 8 by lateral pressure in the direction toward its center (figure 32). In the simplest case, the skin contact area 11 of the puncturing depth reference element 10 which presses against the skin surface 354 during piercing (figure 33) is formed by an appropriately shaped front face of the gripper 350.

In the embodiment shown in figures 31 through 33, the puncturing depth reference element 10 is simultaneously used as a holder for the needle element. The gripper 350 forms fixing means, by means of which the needle element 6 may be fixed in different longitudinal positions in relation to the puncturing depth reference element 10 for adjusting the puncturing depth. In the case shown, the puncturing depth is adjusted by rotating the connecting rod 19 in relation to the gripper arms 351-However, other implementations of the described design principle are possible, also in regard to the fixing means.

In this case, the skin contact area is provided at one of the reusable parts of the puncturing instrument,. To avoid contamination and improve the hygienic conditions, it may be advantageous to provide a disposable protective topcoat on the forward end of the gripper, for example, in the form of a film or in the form of replaceable caps made of plastic. In this case, the gripper 350 does not directly form the skin contact area. Rather it functions as a reference element base part, whose surface (similarly as in figures 26 through 30) is covered by the topcoat, which has the actual s skin contact area.

The illustrated examples show that numerous variants of the present invention are possible. This relates, for example, to the couplers, which provide separate connections, of the needle element and the puncturing io depth reference element to the corresponding positioning parts of the coupling mechanism- However, all embodiments share the feature that at least the needle element, but preferably also the reference element, has a coupler structure which cooperates with a corresponding coupler profile of the positioning part. The terms "coupler structure" and "coupler profile"
is very generally identify any design of the cited elements by which an at least unidirectional, but preferably bidirectional coupling is produced in the meaning explained.

Numerous variants are also possible in regard to the point in time at 20 which the coupling occurs. In particular, constructions may be advantageous for many intended uses in which the coupling by the needle element coupler and/or the reference element coupler occurs only during the forward phase of the puncturing movement. Embodiments in which these couplers open during the retraction phase of the puncturing 25 movement before reaching the starting position of the puncturing drive are also advantageous for many intended uses.

Of course, instead of the coiled springs shown in the figures other spring devices may also be used, such as leaf springs, disk springs, or mutually 30 repelling magnets. The drive during the retraction phase is preferably provided by separate spring elements belonging to the same or different type of spring, As explained at the beginning, the present invention is particularly 3s suitable for integrated systems in which the functions of obtaining blood and of analysis are unified in one device. In the case of a microsampler, this integration is preferably made possible by providing the reagents and other components required for the analysis in its sample receiving area.
In this regard, microsamplers suitable for the present invention do not s differ from known systems. Puncturing units without capillary channels may also be used advantageously in integrated systems accordingly to the present invention. In this case the puncturing unit is retracted rapidly after the puncturing step, so that the sample liquid exiting from the skin may penetrate into a capillary channel of an analysis element, which io inside the puncturing instrument is brought into contact with the sample liquid exiting from the skin.

Claims

1. A puncturing system for withdrawing a body fluid from the skin of a human or animal, comprising:

a needle element (6) for piercing into the skin;

a puncturing instrument (2), which includes a puncturing drive (4), by which a puncturing movement (24) of the needle element (6), which is coupled to the puncturing drive (4) by means of a coupling mechanism (3), is driven;

wherein a) in a forward phase of the puncturing movement (24), the needle element (6) is moved along a predetermined movement path in a piercing direction until its tip (13) penetrates into the skin and, in a retraction phase of the puncturing movement (24), the needle element (6) is retracted after reaching a reversal point corresponding to the puncturing depth in the skin;

b) a predefined value of the puncturing depth is ensured by means of a puncturing depth reference element (10), which has a skin contact area (11), the predefined value of the puncturing depth being determined by the distance in the piercing direction, at the reversal point of the puncturing movement, between the skin contact area (11) and the position of the tip (13) of the needle element (6);

c) the needle element (6) and the puncturing depth reference element (10) are separate elements which can be shifted relative to each other in the piercing direction, and the puncturing depth is adjustable by changing the distance (d) existing at the reversal point between the skin contact area (11) of the puncturing depth reference element (10) and the tip (13) of the needle element (6);

d) the puncturing depth reference element (10) is coupled to the drive by the coupling mechanism (3) in such a manner that it is moved together with the needle element (6) at least during a part of the forward phase of the puncturing movement, and has a defined longitudinal position in the piercing direction in relation to the needle element (6) at least at the reversal point of the puncturing movement; and e) the coupling mechanism (3) includes a needle element coupler (16) comprising a needle element positioning part (16a), which has a first stop (16b), cooperating with a corresponding second stop (6b) of the needle element (6) in such a manner that the longitudinal position of the needle element (6) is at least at the reversal point of the puncturing movement determined by the contact of said first and second stops (16b, 6b), the coupling mechanism (3) includes a reference element coupler (17) comprising a reference element positioning part (17a), which has a third stop (17b), cooperating with a corresponding fourth stop (10b) of the puncturing depth reference element (10) in such a manner that the longitudinal position of the puncturing depth reference element (10) is determined, at least at the reversal point of the puncturing movement, by the contact of said third and fourth stops (17b, 10b), and the longitudinal position at which the needle element positioning part (16a) and the reference element positioning part (17a) are located at the reversal point in relation to one another is changeable for adjusting the puncturing depth.

2. The puncturing system according to claim 1, wherein the puncturing instrument (2) has a housing opening (35) at its forward end in the piercing direction, which is surrounded by a housing skin contact area (33), by which the puncturing instrument (2) abuts against the skin during the puncturing movement.

3. The puncturing system according to claim 1, wherein the puncturing instrument (2) has a stroke adaptor (38), by which the longitudinal position of the reversal point of the puncturing movement (24) is at least partially adapted to the actual position of the skin surface, which varies for different puncturing actions.

4. The puncturing system according to claim 3, wherein the stroke adaptor (38) includes an elastic component (47) cooperating with the puncturing drive (4).

5. The puncturing system according to claim 3, wherein the stroke adaptor (38) includes a detector for detecting the position of the skin surface and a control unit for controlling the puncturing movement as a function of the detected position of the skin surface.

6. The puncturing system according to claim 5, wherein the control unit is implemented in such a manner that the acceleration of the puncturing unit in the direction toward the skin during the forward phase of the puncturing movement is interrupted upon contact of the skin contact area (11) of the puncturing depth reference element (10) with the skin surface.

7. The puncturing system according to claim 5, wherein the position of the skin surface is detected before triggering a puncturing movement and the subsequent puncturing movement is adapted to the detected position.

8. The puncturing system according to claim 1, wherein, during the forward phase of the puncturing movement, at least at the contact instant at which the skin contact area (11) contacts the skin surface, the distance between the skin contact area (11) and the tip (13) of the needle element (6) is less than the predefined value of the puncturing depth, so that the skin is tensioned by the impact of the skin contact area, before the puncturing movement of the needle element reaches the reversal point.

9. The puncturing system according to claim 8, wherein, during the forward phase, at least at the contact instant, the tip (13) of the needle element (6) is located behind the skin contact area (11) in the piercing direction, so that the skin is tensioned by the impact of the skin contact area before the piercing into the skin occurs.

10. The puncturing system according to claim 1, wherein the pressure with which the skin contact area (11) of the puncturing depth reference element (10) presses against the skin surface during the forward phase of the puncturing movement is so high that deterioration of the reproducibility of the puncturing depth by a skin deformation, occurring during piercing of the needle element into the skin, is reduced thereby.

11. The puncturing system according to claim 1, wherein the puncturing drive (4) is coupled to the needle element (6) during at least a part of the forward phase and the reference element (10) is coupled to the needle element (6) and thus to the puncturing drive (4) by means of a co-transport device (103) during at least a part of that part of the forward phase in which the needle element (6) is coupled to the puncturing drive (4).

12. The puncturing system according to claim 11, wherein the co-transport device (103) has puncturing depth limit stops (101, 125), one of which is coupled to each of the needle element (6) and the puncturing depth reference element (10), and the puncturing depth limit stops (101, 125) are in engagement with one another at the reversal point of the puncturing movement in such a manner that their relative distance in the longitudinal direction defines the longitudinal position of the needle tip (13) in relation to the skin contact area (11) of the puncturing depth reference element (10) and thus the puncturing depth.

13. The puncturing system according to claim 11, wherein the puncturing depth reference element (10) is, during the section of the forward phase of the puncturing movement preceding the contact instant, elastically coupled via the co-transport device (103) to the needle element (6) and thus to the puncturing drive (4).

14. The puncturing system according to claim 11, wherein the puncturing depth reference element (10) is coupled via a bi-directionally acting co-transport device (103) to the needle element (6) and thus to the puncturing drive (4), said co-transport device (103) comprising stops (143, 144) acting in the retraction phase, one of said stops being coupled to each of the needle element (6) and the puncturing depth reference element (10).

15. The puncturing system according to claim 14, wherein said stops (143, 144) are in engagement with one another during at least a part of the retraction phase in such a manner that the position of the needle tip (13) in relation to the skin contact area (11) of the puncturing depth reference element (10) is defined thereby and said stops (143, 144) acting in the retraction phase are positioned in such a manner that they define a residual puncturing depth by which the needle tip (13) protrudes in relation to the skin contact area (11).

16. The puncturing system according to claim 1, wherein the diameter of the skin contact area is at least 1.5 mm and at most 6 mm.

17. The puncturing system according to claim 1, wherein the puncturing depth reference element (10) rests, during a part of the forward phase, in a rest position by means of a reference base part (146) on a reference element bearing (105), and the puncturing depth reference element in the forward phase, starting from the rest position, is accelerated in the piercing direction by the piercing drive (4).

18. The puncturing system according to claim 17, wherein the partial section of the puncturing movement, during which the puncturing depth reference element (10) is moved together with the needle element (6), lasts at most 100 ms.

19. The puncturing system according to claim 17, wherein the partial section of the puncturing movement, during which the puncturing depth reference element (10) is moved together with the needle element (6), lasts at most 50 ms.

20. The puncturing system according to claim 17, wherein the partial section of the puncturing movement, during which the puncturing depth reference element (10) is moved together with the needle element (6), lasts at most 10 ms.

21. The puncturing system according to any one of claims 1 to 20, wherein the puncturing drive (4) is implemented in such a manner that the retraction phase of the puncturing movement immediately directly after reaching the reversal point.

22. The puncturing system according to any one of claims 1 to 20, wherein the needle element has a capillary channel (70), through which a body fluid may be transported from the skin into a sample receiving area (71) of the needle element (6) and the puncturing drive (4) is implemented in such a manner that the movement is interrupted or slowed during the retraction phase after reaching the reversal point for a time period (S) required for suctioning the body fluid.

23. The puncturing system according to any one of claims 1 to 22, wherein the drive (4) and its coupling to the puncturing depth reference element (10) and the needle element (6) are arranged and adapted such that the distance in the piercing direction between the skin contact area (11) of the puncturing depth reference element (10) and the position of the needle tip (13) is reduced after reaching the reversal point to a defined residual puncturing depth, the puncturing movement is slowed or stopped upon reaching the residual puncturing depth, and thereafter the needle (8) of the needle element (6) is pulled out of the skin.

24. The puncturing system according to claim 23, wherein the time from reaching the reversal point until reaching the residual puncturing depth is at most 2 seconds.

25. The puncturing system according to claim 23, wherein the time from reaching the reversal point until reaching the residual puncturing depth is at most 1 second.

26. The puncturing system according to claim 23, wherein the time from reaching the reversal point until reaching the residual puncturing depth is at most 0.5 seconds.

27. The puncturing system according to any one of claims 1 to 26, wherein the puncturing instrument (2) is a multiple use item and comprises a holder (27), by means of which a puncturing unit (1) interchangeable may be coupled to the puncturing drive (4), at least the skin contact area (11) of the puncturing depth reference element (10) being formed on a single-use disposable element.

28. The puncturing system according to claim 27, wherein the puncturing depth reference element (10) has a reference element body (12), which extends from the skin contact area (11) opposite to the piercing direction and at least partially encloses a body part (7) of the needle element (6) and in that the longitudinal position of the needle element (6) in relation to the longitudinal position of the reference element body (12) is changed during the retraction phase of the puncturing movement or afterwards before the removal of the puncturing unit (1) from the holder (27) in such a manner that the needle tip (13) is retracted behind the skin contact area (11) of the puncturing depth reference element (10) for protection from injuries.

29. The puncturing system according to claim 27, wherein it includes a magazine including a plurality of needle elements (6).

30. The puncturing system according to claim 27, wherein it has a puncturing depth reference element (10), which is adapted and arranged for cooperation with a plurality of needle elements (6) of the magazine (85), which are transported in sequence into a position in which one needle element (6) at a time may be moved together with the puncturing depth reference element (10) during at least a part of the puncturing movement.

31. The puncturing system according to claim 27, wherein it includes a needle element strip (331) including a plurality of needle elements (6), which are fixed on a carrier film (328) and sealed in such a manner that their needle tips (13) are hygienically protected, it has a transport device, by which the needle element strip (331) is transported step-by-step in the puncturing instrument such that one needle element (6) at a time is located in a puncture station (332) at a reference element base part (333), it comprises a puncture preparation device (335), by which the needle element (6) located in the puncture station (332) is brought into a puncture position, in which its needle tip (13) is exposed and oriented in the piercing direction, while the carrier film covers the reference element base part (333) in the surroundings of the needle tip (13) and forms the skin contact area (11), the reference element base part (333) is moved together with the carrier film (328) forming the skin contact area (11) during the puncturing movement and forming the puncturing depth reference element (10).

32. The puncturing system according to claim 31, wherein the carrier film is at most 100 µm thick.

33. The puncturing system according to claim 31, wherein the carrier film is at most 50 µm thick.

34. The puncturing system according to claim 31, wherein the carrier film is at most 30 µm thick.

35. The puncturing system according to claim 31, wherein the needle elements are sealed by means of a cover film (329), having a thickness of at most 50 µm.

36. The puncturing system according to claim 31, wherein the needle elements are sealed by means of a cover film (329), having a thickness of at most 25 µm.

37. The puncturing system according to claim 31, wherein the needle elements are sealed by means of a cover film (329), having a thickness of at most 15 µm.

38. The puncturing system according to claim 27, wherein the puncturing depth reference element (10) is adapted to function as a holder for the needle element (6) and has fixing means, by means of which the needle element (6) may be fixed in different longitudinal positions in relation to the puncturing depth reference element (10) for adjustment of the puncturing depth.

39. A disposable puncturing unit (1) for withdrawing a body fluid from the skin of a human or animal, for use as a component of a system in which one disposable puncturing unit (1) at a time may be replaceably coupled to a puncturing drive (4) provided in a puncturing instrument (2) of the system, the puncturing unit comprising:

a needle element (6) for piercing into the skin in a piercing direction; and a puncturing depth reference element (10), by which a maximum puncturing depth of the needle in the skin is limited in that a skin contact area (11) of the puncturing depth reference element (10) contacts the skin, whereby a predefined value of the puncturing depth is ensured;

wherein a) the longitudinal position in the piercing direction (24) of the puncturing depth reference element (10) in relation to the needle element (6) and thus the distance between the skin contact area (11) and the needle tip (13) is changeable to adjust the predefined puncturing depth;

b) the puncturing unit (1) is during the puncturing movement (24) coupled to the puncturing drive (4) by means of a coupling mechanism (3);

c) the coupling mechanism (3) comprises a needle element positioning part (16a), and the needle element (6) has a coupling structure, which cooperates with a corresponding coupling profile of the needle element positioning part (16a) for coupling the needle element (6) to the needle element positioning part (16a); and d) the coupling mechanism also comprises a reference element positioning part and the puncturing depth reference element (10) also has a coupling structure, which cooperates with a corresponding coupling profile of the reference element positioning part for coupling the reference element to the reference element positioning part.

40. The disposable puncturing unit according to claim 39, wherein the needle element (6) has a capillary channel (70), through which body fluid may flow from the skin into a sample receiving area (71) of the needle element (6).

41. The disposable puncturing unit according to claim 40, wherein it has a window (79), for allowing an optical measurement on a fluid in its sample receiving area (71).

42. The disposable puncturing unit according to claim 40, wherein it has electrical contacts for performing an electrical measurement on a fluid in its sample receiving area (71).