HK1060966B - System for withdrawing blood - Google Patents

Description

System for drawing blood

Technical Field

The present invention relates to a system for extracting body fluid from a body part, in particular a fingertip, by generating a small puncture wound.

Background

There is a need in the clinical diagnostic field to obtain samples of body fluids, particularly blood samples, in order to detect components therein. If a larger blood volume is required, it is usually withdrawn by means of a syringe or similar device, for which purpose the blood vessel is penetrated. The invention is however in the field where only a blood volume of a few mul or less is needed to determine the analysis parameters. Such a mode of operation is particularly widely used in the measurement of blood glucose levels, but it is also used, for example, for determining the blood coagulation parameters, triglycerides, HBAlc or lactate. In the field of diabetes, it has become generally accepted by diabetics who self-monitor blood glucose levels (so-called home monitoring). This is necessary in order to maintain blood glucose levels within a normal range by a dose of insulin. Conversely, if a diabetic falls into a hypoglycaemic (hypoglycemic) state, it may lead to the patient becoming unconscious or even dying. If the patient becomes in a state of high blood glucose level, serious consequences such as blindness or gangrene may result. In order to draw the amount of blood necessary for measuring blood glucose levels, small, portable blood sample drawing devices, so-called lancing aids, are used, which can be used simply and reliably by users, medical staff. Recently known systems for extracting interstitial fluid can in principle be used to perform corresponding analytical sampling.

An increasingly important problem in this field is contamination and resulting injury to the lancet after use. In many commercially available devices, the lancet is removed after the lancing process and discarded. The exposed lancet tip in such a situation may cause injury, which may lead to infection. Efforts have therefore been made in many countries to prohibit the use of such blood sampling systems in which the needle tip is freely accessible after use.

Various variants of blood sample withdrawal systems are disclosed in the prior art documents in which the needle is protected after the puncturing procedure. In document US5,314,442, a cap is described in which a lancet is arranged. To perform the lancing process, the lancet is pushed inside the cap by a push rod or similar device, and the needle is extended outwardly through an aperture. After the puncture, the lancet is again retracted into the cap, and the resilient element on the lancet ensures that the lancet tip can no longer protrude outward without being used by the push rod. Systems based on similar principles are disclosed in US patents 4,991,154 and 5,074,872 and in international application WO 00/02482. Document DE 19855465 discloses another system in which the lancet is retracted into the cap by an interposed spring. Although the above-mentioned documents have addressed the problem of contamination or injury to the user, the connection of the drive mechanism to the lancet is achieved only by a press fit. The penetration depth of the needle is limited by a stop. However, it has been shown that the collision of the lancet with the stop causes a vibration of the needle, which increases the pain during the puncture. This problem is explained in detail in EP 0565950.

Disclosure of Invention

The object of the present invention is to provide a system for drawing off body fluid which on the one hand avoids contamination or injury due to the used lancet and on the other hand makes it possible for the user to reduce much pain when performing a puncture. Another task is to simplify the systems of the prior art, making them more cost-effective, and in particular to propose a solution that makes it possible to reduce the size of the system. The latter point is particularly important in order to provide a system for handling lancets contained in a magazine and which allows the user to select a lancet which is not yet used without having to perform complicated manual steps.

The above-mentioned object is achieved by embodiments of systems for extracting a body fluid, which have a drive unit with a plunger which is moved from a rest position into a puncturing position in order to carry out a puncturing procedure. The system furthermore comprises a lancing unit in which a lancet with a needle is arranged, which needle is arranged inside the lancing unit in the rest position of the plunger and which needle is pushed into the lancing position by the plunger when it is moved, in such a way that the needle projects at least partially out of the lancing unit through the opening. An important feature of the system is that the push rod for carrying out the puncturing operation is connected to the lancet by a form-fit connection.

A form-locking feature in the sense of the present invention is that the lancet can be connected to the drive plunger with little effort. There are two basic variants for realizing the form-locking. In a first variant, the lancet is connected to the drive plunger and is closed into a shape in such a way that the retaining element is closed. This closed shape is referred to as a retaining means within the scope of the invention. If the holding device is located on the lancet, the drive plunger has a holding element; if the holding device is located on the drive plunger, the holding element is arranged on the lancet. Figures 1 and 2 show a practical embodiment. The form-locking variant is preferably realized in that the transverse movement of the holding element of a (initially open) holding device is realized by a longitudinal movement in the puncturing direction, in which case the holding device is closed around a holding section. Preferably, the retaining device grips the retaining element (at least partially) during closing, so that the lancet moves with it during retraction of the drive plunger, at least as far as a possible opening of the retaining device. Furthermore, it is advantageous if the retaining device and the retaining section are geometrically matched to one another in such a way that, after the positive locking has been achieved, there is no or only a small error in the direction of the puncturing movement, and that a movement of the drive plunger, both in the puncturing direction and in the opposite direction, is converted into a movement of the lancet without play. This can be achieved when the longitudinal extension of the chambers in the closed holding device is equal to or only slightly greater than the longitudinal extension of the holding sections (see fig. 1). In a further embodiment of this variant, the recesses of the retaining segments and the retaining elements on the retaining device are matched to one another in their longitudinal extent in such a way that a substantially play-free transport in the puncturing direction is possible (see fig. 2).

In a second variant of the form-locking, both the holding device and the holding section are substantially form-stable, the holding section being enclosed by the holding device, which is achieved by the above-mentioned movement of the two unit shapes towards each other. Because the units are shape stable, a complete closure is not possible, but the shape must be opened to such an extent that they can move towards each other. The opposite movement (at least via one path section) is effected transversely to the piercing direction, which results in a connection which is likewise substantially free of play in the piercing direction (see fig. 4). Finally, a connection can also be realized by a movement which includes not only a movement of the component transverse to the puncturing direction, but also a movement parallel to the puncturing direction (see fig. 7).

The system according to the invention for taking blood samples has a drive unit with a push rod by means of which the lancet is moved from a rest position into a puncturing position. In the prior art, a series of drive mechanisms are known, which can be applied in the field of blood sample drawing devices. In particular, drive mechanisms which derive their energy from a pretensioned spring are used in a wide range. Within the scope of the invention, a drive unit is preferably used, which can guide the movement of the plunger and the lancet by means of a form-locking connection. One guided motion means: the lancet not only punctures the body along a predetermined path, but also retracts after passing a predetermined path-time curve. In the conventional systems based on a combination of springs and stops in the prior art, this path-time course is influenced by various parameters, such as manufacturing tolerances (frictional properties in the system, spring strength) and skin surface properties. It has proven advantageous for the pain caused by the puncture to be caused by a guided movement of the lancet, for example by means of a guide crescent as described in EP 565970. With regard to the drive unit, the preferred drive mechanisms of EP 565970 and US 4,924,879 are incorporated herein by reference.

An important aspect of the invention is that a puncturing unit having at least one lancet can be removed from the drive unit. The lancing unit includes a housing in which the lancet is in a resting position. Injury or contamination of the lancet prior to or after use is thereby prevented. The housing can be designed such that only a single lancet is arranged therein, or it can be in the form of a cassette with several lancets. Typically, the lancets in the cassette are located in separate chambers from each other to prevent contamination of the unused lancets from used lancets. It is advantageous to design the housing of the puncture unit such that it can be mounted to the drive unit. For this purpose, the puncturing unit can have the form of a cap, for example, which can be slipped onto the drive unit. Such embodiments are disclosed, for example, in documents US5,314, 42, US 4,990,154 and US5,074,872. Embodiments are also possible in which the puncturing unit is fixedly connected to the drive unit or is an integral part of the drive unit. This is particularly advantageous in systems with cartridges, so that the entire unit can be thrown away after use of the cartridge. In the case of a cartridge-like form of the puncturing unit, the cartridge has, for example, chambers arranged next to one another, in which the lancets are located, which chambers are situated relative to one another in such a way with respect to the drive unit that the lancets can be connected to the push rod of the drive unit. It is also advantageous for a cassette to have chambers in the form of a cylinder, which are arranged parallel to the longitudinal axis of the cylinder, in which chambers the lancets are located. The same applies to a magazine like a revolver wheel which is re-mountable to the drive unit.

Another requirement for the lancing unit is the disinfection of the lancet, which must be ensured for a long time. As is commonly used in the prior art, a sterilization of the lancet can be achieved by gamma radiation. To maintain sterility, the puncturing unit may be sealed in a closed bag, such as a polyethylene bag. In another embodiment, the opening of the puncture unit (for inserting the plunger and for piercing the needle tip) is closed with a sealing film. The sealing membrane may for example be a sealing membrane which is removable by the user before use. However, it is preferred that a membrane be used which is pierced by the plunger or by the needle tip during use, so that the user is relieved of additional manual steps. Such a membrane has been incorporated into the manufacturing process of the puncture unit, which is typically an injection molding process.

In another preferred embodiment, the needle tip is protected from contamination by an elastomer that is removed prior to piercing or pierced during piercing to expose the needle tip. Such a form of protection of the needle against contamination is disclosed in the application document WO 01/66010. Which is incorporated herein by reference.

One or more lancets with a needle are provided in the lancing unit. Apart from the possible devices on the lancet, i.e. devices which can be connected in a form-locking manner to the push rod, lancets which are known from the prior art can be used within the scope of the invention. Generally, such lancets have a plastic body in which a metal needle is arranged. However, lancets without a separate body are also possible (e.g. the metal would have a thickening at the rear end as a retaining section).

It is expedient within the scope of the invention for the plunger of the drive unit and the lancet to be connected to one another by a form-fit for carrying out the puncturing operation. The invention is distinguished essentially from the prior art, in which the mechanical connection between the lancet and the drive device is realized by a press fit (US 5,314,442, US 4,990,154, US5,074,872), a locking device (WO 00/02482), a clamping device (US 4,030,959) or by a simple pressing (DE 19855465). A form-locking feature is that a reliable mechanical connection between the drive device and the lancet is achieved, but as a result substantially no pressure is generated on the lancet in the direction of the puncturing movement. In the case of devices of the prior art which operate with a press fit, it is necessary to provide a spring element (e.g. DE 19855465) or a return holding element (e.g. WO 00/02482) in the cap containing the lancet, which are designed such that the lancet does not protrude from the cap when the lancing unit is connected to the drive unit. However, the introduction of the spring element in the puncture unit increases the manufacturing costs, which is particularly serious since the puncture unit is a consumable material. In order to overcome the restoring holding element, additional forces need to be applied to the drive unit side, which forces lead to vibrations of the needle, which adversely affect the puncture pain. Furthermore, in devices that work with a press fit, a guided movement involving retraction of the lancet is problematic, since this can thereby release the press fit. The locking device disclosed in WO00/02482 solves this problem, which is however technically difficult to achieve. The realization of such a locking device in a conventional manufacturing process is particularly complicated, since very small fluctuations in the material or process conditions can lead to a failure of the device. Another disadvantage of the device disclosed in WO00/02482 is that the locking takes place in the region of the path for piercing the body. The force fluctuations or vibrations caused by this locking will negatively affect the puncture pain. Another disadvantage of this device is that the needle is retained after insertion into the body and does not retract actively. The needle is retracted only when the cap is removed from the drive mechanism. In contrast, in the form-locking connection of the drive plunger to the lancet according to the invention, a connection between the plunger and the lancet can be realized, for which purpose no special forces have to be applied in the puncturing direction, and the form-locking connection is advantageous for actively retracting the needle after puncturing. The possibility of effectively controlling the path-time curve of the needle by means of the drive unit makes it possible to carry out the puncturing procedure with little pain.

Fig. 8 schematically shows the force F-path s curve for the connection of the drive device to the lancet by press fit a, locking device b and form-locking c. It can be seen that when a press fit is used, the force increases significantly until the needle is released from its position held by the retaining element or spring. In the case of a locking device, the force increases during the locking process and decreases again after the closure has been achieved. In the case of a form-locking, only a small force is required to move the holding elements together.

Another characteristic of the form-locking according to the invention is evident by the combination with document US 3,030,959. In the device according to the US patent, the needle arranged in a tube is successively held by a clamping mechanism similar to a mechanical pencil. Furthermore, this device does not solve the problem of contamination caused by the needle after use, it being seen that the positioning of the needle in the axial direction (i.e. in the direction of penetration) is not limited, as in the case of a mechanical pencil, the user is free to choose the length of the pencil point that is extended, where the axial length of the needle is adjusted by the user. In contrast, in the form-locking principle, the lancet and the drive unit have a holding section and a holding device which are adapted to one another. The axial positioning of the lancet can be defined by the geometry of the holding section and the holding device, and the penetration depth can thus be precisely controlled. Using a form-locking connection, force peaks in the axial direction are thus avoided when the lancet is connected to the drive plunger, and precise axial positioning is achieved. In form closure, one shape (retaining device) is closed around the other shape (retaining section). In this context, a self-closing means not only a movement of the device part transverse to the puncturing direction, but also, alternatively, a form-locking mutual clamping of the two shape bodies, the shape of which does not change. In a preferred embodiment, the retaining device is open and closes around the retaining section when it enters the retaining device. In particular, the closure can be effected by a longitudinal movement which is converted into a movement of the holding element of the holding device with the component transverse to the direction of the longitudinal movement. A practically advantageous possibility is to convert this longitudinal movement into a transverse movement in order to move the holding device by the longitudinal movement into a tapering channel (for example a sleeve) or slide it into it (see fig. 1). In this case, the term tapering means not only a continuously tapering channel, but also all channels whose internal width decreases in the longitudinal direction. In this respect, the channel need not be a circumferentially closed body. When, for example, the holding device has two opposing hooks as in fig. 1, only two walls are required whose mutual internal distance is reduced.

On the other hand, it is also possible to close the retaining device by releasing a tensioned state (see fig. 2), which can be achieved, for example, by moving the retaining device in a widened passage.

According to a preferred embodiment of the invention, the holding device has at least two elastic elements which move towards one another when the push rod is connected to the lancet.

According to a further preferred embodiment of the invention, the holding device has two or more holding elements which are closed when the puncturing unit is placed on the drive unit, so that they hold the holding section of the lancet. The holding elements are connected to a spring element which moves the holding elements toward one another. The holding elements can be tensioned against the force of the spring element by means of a tensioning element, so that they are spread apart, the puncture unit being placed on the drive unit to release the tensioning element, so that the holding elements are moved towards one another.

According to a further preferred embodiment of the invention, the device for extracting body fluid according to the invention further has an adjustment device for adjusting the extent to which the needle projects from the puncture unit.

Drawings

The invention is described in detail with the aid of the accompanying drawings:

FIG. 1: cutting a cross-sectional view of a lancing unit having a retaining device on a lancet;

FIG. 2: cutting a cross-sectional view of a section of the system with a retaining device on the drive unit;

FIG. 3: cutting a cross section of the whole system and an operation step;

FIG. 4: a system section with a form-stable holding device on the drive unit;

FIG. 5: a cartridge of a puncture unit;

FIG. 6: a system consisting of a drive unit and a puncture unit;

FIG. 7: a system with a form-stable holding device;

FIG. 8: force-distance curves for various connection types;

FIG. 9: a lancet with a sterility protection device;

FIG. 10: a cylindrical box.

Detailed Description

Fig. 1 shows a blood drawing system according to a first exemplary embodiment of the present invention in operating phases I, II and III. Only some aspects of the system are shown in fig. 1. The drive unit for the plunger 10 and its housing, to which the puncturing unit 20 is fastened, are not shown in this figure. The drive device described in EP 0565970 is particularly suitable as a drive unit for the tappet 10.

The phase shown in fig. 1 represents the progression of the form-locking connection between the plunger 10 and the lancet 30 and the actual puncturing process. For each of these three phases, two cross-sections are shown in each case in planes perpendicular to one another along the longitudinal axis of the system. As can be seen from the left side view of stage I, the lancet 30 is disposed within the casing 40. The lancet 30 shown has a body made of plastic and a needle 31 made of steel molded into the body. The lancet has a holding device on the side facing away from the piercing tip, which has a holding element in the form of a double hook 32a, 32 b. When the plunger 10 enters the lancet, a thickened area on the front end of the plunger, which acts as a retaining section, passes between the hooks 32a, 32b and finally hits the rear needle end (phase II). It may also allow the push rod to impact the lancet body rather than the rear needle end. However, direct contact with the needle is advantageous, since the needle length and thus the penetration depth can be controlled very precisely from a production point of view. As the plunger is pushed further forward, it pushes the lancet within the sheath 40 in the direction of the aperture 40, eventually causing the tip of the lancet to pierce out of the aperture and into the underlying tissue. As can be seen from the transition from phase II to phase III, the retaining means 32a, 32b on the lancet close off the retaining section 11 of the push rod as soon as the lancet is moved into the sleeve 40. The holding device on the lancet grips the holding element of the push rod in such a way that a form-locking connection is formed, by means of which connection not only the forward movement of the lancet for puncturing can be carried out, but also the effective retraction of the lancet can be controlled by the drive unit substantially without play. This is ensured on the one hand by the end of the holding section which rests on the needle end and on the other hand by the hooks 32a, 32b which clip behind the rear end of the holding section. The length of the holding section and the longitudinal extension of the chamber in the closed holding device are matched to one another in such a way that a play-free driving of the lancet in the puncturing direction is made possible. The retaining device can be positively locked with the retaining section of the drive device by arranging the lancet or the retaining device in a tapered sleeve such that a longitudinal movement of the lancet in the puncturing direction is converted into a transverse movement of the elements of the retaining device. As shown, the sleeve 40 has a middle region 40b that is tapered compared to the open region 40 a. By means of this tapering, the hooks 32a, 32b of the lancet are pressed together when the lancet is moved in the sleeve along the longitudinal axis, so that the retaining section 11 is sealed. It has proven to be particularly advantageous to design the puncture unit 20 such that it is held in the housing when it is not acted upon by the plunger. It is thereby ensured that the needle is in the unloaded state in the sleeve 40, whereby no injury or contamination due to the protruding needle tip occurs. The protrusion of the lancet out of the sleeve in the direction of the opening 41 is effectively prevented by the hooks 32a, 32b having a shoulder which rests against the edge of the central region 40 b. The inclination of the edges and the elasticity of the hooks can be adapted to one another in such a way that, on the one hand, a low force can be used to enter the tapering structure and, on the other hand, an accidental projection is effectively avoided. In order to prevent the lancet from protruding from the sleeve in the opposite direction to the puncturing direction, in the illustrated embodiment, a widened portion 40c is provided at the rear end of the sleeve and a correspondingly widened portion 30a is provided at the rear end of the lancet body.

As shown in fig. III, the needle tip remains in the sheath 40 when the holding section 11 hits the needle end. This is advantageous because the impact generated by the collision does not affect the puncturing process in the tissue, thereby preventing puncturing pain due to such impact.

Preferably, when the system is designed such that after phases I, II and III have been extended, the retraction movement of the push rod 10 can be effected in the opposite direction, so that the push rod is disconnected from the lancet, which is still completely contained in the sheath. There are two main variants for the connection of the push rod to the lancet. In a first variant, the housing, the drive unit and the puncture unit are adapted to one another in such a way that the plunger is completely outside the puncture unit 20 in the initial state (as shown in stage I). A disadvantage of this embodiment is that the push rod has to travel a relatively long path to perform the puncture. However, one advantage is that the push rod is completely outside the puncture unit, making lateral movement possible. Accordingly, this first variant can be advantageously used in systems with lancet magazines, in which various sleeves are moved one next to the other under a push rod. In a second variant, a position according to phase II or in addition a position according to phase III is already reached by the connection of the piercing unit to the drive unit. In such an embodiment, the path that the push rod has to travel is kept very small, which is advantageous from a constructional point of view.

Fig. 2 shows a second embodiment of the invention, in which the lancet 130 has a holding section 131 and the drive unit has a holding device 132a, 132 b. The area of the system for holding the lancet is also shown in fig. 2, but the drive unit is not shown. It is also advantageous to use a drive unit in connection with this embodiment, which drive unit moves the push rod 110. The push rod is supported on the front end of a holding device with holding elements in the form of double hooks 132a, 132b, which are connected to one another by an elastic bridge 133 (or a hinge). This arrangement forms a spring element. In phase I, the two hooks are spread apart because their rear ends are held together by the sleeve 140. When the lancet 130 is inserted, the sleeve simultaneously pushes the spring 141 in the opposite direction, so that the rear end of the hook is released and the front end of the hook encloses the holding section 131 of the lancet in a form-fitting manner. The holding section of the lancet has a recess into which the hook of the holding device engages. The longitudinal extension of the engaging end of the holding means (in the puncturing direction) and the longitudinal extension of the recess are substantially identical, so that a guided, substantially play-free puncturing movement can be carried out by this arrangement. Also in this embodiment, a conversion of the longitudinal movement of the holding device into a transverse movement of the holding element is achieved.

Fig. 3 shows a system according to the invention, which is based on the form-locking connection shown in fig. 2. The drive unit 100 is based on Softclix as explained in EP B0565970^Provided is a device. It is known in particular from this document how the rotary movement of the sleeve 171, which is produced by means of the drive spring 170, is converted into a transverse movement of the push rod 110. The tension of the drive spring generated by pressing the button 172 and a mechanical transition suitable for this are described in the european patent application EP 00102503.0. The drive unit has a holding device with two holding elements, in particular hooks 132a, 132b, at the front end. As already matched with the figure2, the hooks are connected to each other in an intermediate zone by an elastic bridge 133 or a hinge. The retaining device is secured on the side of the hook facing away from the bridge 133 by means of a sleeve 140 in such a way that the hook is spread open. The sleeve 140 is held in place by a spring 141 located in the drive. Fig. 3 also shows a lancing unit, in which a lancet 130 is arranged in a cap 121. The lancet is provided with a holding section 131 at its rear end, which is to be clamped by the holding means 132a, 132 b. The outer body of the lancet has a forward narrow region and a flange 122 between the narrow region and the retaining section region 131. The tip of the lancet is protected from contamination and mechanical influences by a breakable plastic body 123. The cap 121 has a passage for the narrow region of the lancet in its interior and an area of larger cross section suitable for receiving the flange 122. A boss 124 is provided within the widened channel of the cap which prevents the flange from independently extending back into the widened channel. The cap also has a sleeve 125 which functions to move the sleeve 140 of the drive unit backwards when the puncturing unit is placed on the drive unit. This process can be seen from the combination of fig. 3I and 3 II. By pushing the sleeve 140 by means of the sleeve 125, the holding device is released, which encompasses the holding section of the lancet, as can be seen from fig. 3 II. By pressing the button 172 and twisting off the protective portion 123 of the lancet, the system is ready for use. The puncturing procedure can be performed with the device shown in fig. 3II, wherein the front end of the cap 120 is placed on the tissue portion and the drive unit is activated by operating a trigger mechanism. After the puncturing procedure has been performed, the cap is pulled in the direction of the longitudinal axis from the drive unit, wherein after the flange 122 has been pulled over the projection 124, the contaminated needle tip can no longer protrude from the cap. In the state shown in fig. 3III, the puncture unit can be disposed of or used for further sampling procedures after being connected to the drive unit.

Fig. 4 shows a third exemplary embodiment of the invention, in which the form-locking connection between the lancet and the drive device is realized by a form-locking connection of the holding section and the holding device which are geometrically matched to one another. In fig. 4A, a puncture unit 220 is shown with a sheath 240 in which a metal needle 231 is present. The sleeve 240 has a thin transverse wall 250 which retains the metal needle relative to the sleeve. The transverse wall is preferably formed at the same time as the needle is injection moulded in the plastic. Due to the relatively small thickness of this wall, the mechanical attachment of the hub to the needle is released during the puncture process, allowing the needle to slide past the transverse wall 250. At the opening of the sleeve, this opening is closed by a thin membrane 260 which is pierced during the piercing process. The needle 231 carries an injection-molded retaining section 232 at its upper end. For mechanical stability, the needle has a tapered portion injection molded around the retaining section 232, thereby preventing axial movement. The retention of the needle in the sleeve can also be achieved by a roughness of the needle on its outer surface, a thickening or a bending of the needle in the region of the sleeve. The drive ram 210 of this embodiment has a retaining device 211 at its lower end, which engages over the retaining section 232 in a form-fitting manner as shown. The holding device 211 is open on one side, so that the plunger can move the holding device 211 parallel to the needle offset to the height of the holding section 232 and engage with the holding section of the needle by a movement transverse to the needle axis or transverse to the puncturing direction. After these positive locks have been achieved in this way, the needle is not only driven in the puncturing direction by the plunger 210, but can also be retracted effectively. In the example shown, the holding section of the lancet has a recess (indentation) into which a projection of the holding device engages when connected, so that the two body parts are connected to one another substantially without play in the puncturing direction.

Fig. 4B shows a cartridge which is formed by the puncturing unit 220 according to fig. 4A. With reference to the coordinate system shown, the drive plunger 210 engages with the holding section of the lancet by a movement in the Y direction (perpendicular to the plane of the drawing) or releases the form-locking again. When the form lock is released, the drive ram is moved in the X direction (left/or right) to the level of the other lancet and again engages with the lancet by movement in the Y direction, so that the lancets in the magazine can be operated one after the other. After the form-locking has been formed, the needle can be moved effectively not only in the positive Z-direction but also in the negative Z-direction (up/down).

The connection of fig. 4B requires a movement of the push rod not only in the X-direction but also in the Y-direction, alternatively the connection according to fig. 4B can be realized by only one movement in the X-direction. For this purpose, the plunger has, for example, opposing hooks, between which a passage for a holding section of the lancet is arranged in the X direction. By moving in the X direction, the push rod can be moved from one lancet to another in order to carry out the puncturing operation in the Z direction. If the push rod is at the level of a lancet in the X direction, the holding device of the push rod encloses the holding sections of the lancets in a form-fitting manner, and the lancets can be moved by guiding the push rod in the Z direction, whereby the push rod performs the puncturing movement and the lancets are retracted again effectively.

Fig. 5 shows an automatic operating system with a puncture unit according to fig. 1. As seen in plan view (fig. 5B), the puncture units 20, 20' etc. are adjacently fixed to one conveyor belt. The conveyor belt 301 runs around two shafts 302, 303 at a distance from each other. One of the shafts is driven by a motor to move the puncture unit successively through the connection site 305. In this position, as shown in fig. 4a, a drive ram 10 can be positively connected to a puncturing unit 20 located in the puncturing position 305.

Fig. 6 shows a drive unit to which a puncture unit similar to the embodiment of fig. 1 is connected. The drive system shown corresponds to the drive system of the european patent application with document No. EP 00102503.0. In this drive system, by pressing the button 420 against the tension of the spring 418, the sleeve 414 is rotated axially, tensioning the second spring 415. The sleeve 414 is locked in an end position, keeping the second spring 415 in tension. When the user releases the locking means, the spring 415 is relaxed and the sleeve 414 is rotated in the opposite direction to that during tensioning. In the sleeve 414 there is a notch which serves as a guide crescent for the feed cylinder 408 which carries on its outer surface a pin or the like which engages into the notch. Rotation of the sleeve 414 translates into translational movement of the feed cylinder. The feed cylinder transmits its feed movement to a drive ram 480, which has a holding section at its front end.

The drive unit also has a holding section 450, on which a puncture unit is mounted or screwed. The lancing unit includes a cap 470 having a face on the major outer surface for pressing. A sleeve 471 is provided in the cap, in which sleeve a lancet 472 is provided, which lancet has a retaining device on its side facing away from the piercing tip. The holding means of the lancet correspond to the holding means 32a, 32b of fig. 1. As can be further seen from fig. 5, a form-locking connection of the lancet with the drive ram has been achieved by the cap 470 being arranged on the drive device.

Figure 7 shows a system for extracting body fluid having many similarities to the system shown in figure 3. Reference is made in particular to the description of the drive mechanism and the tensioning mechanism made in fig. 3 and 6. The system according to fig. 7 has a puncturing unit 120 ' with a cap 121 ' and a lancet 130 '. In the cap 121' there is an axial channel through which the lancet body can move during the lancing process. Preferably, both the channel and the lancet body are adapted to one another such that the lancet is guided axially during the puncturing process, but only with a small gap in the transverse direction. The cap has a screw thread 126 at its rear end which can be screwed onto a corresponding screw thread 127 of the drive unit 100'. The lancet has one or more (in the case shown, 2) pins 131 'on the end opposite the piercing tip, which form-locking with a holding device 132' when the cap is placed or screwed onto the drive unit. For this purpose, the holding device has a groove or recess which has an axial portion 134a and a portion 134b arranged transversely to the axial portion. Upon placing the cap onto the drive unit, the pin 131' enters the axial part of the recess 134 and continues to enter through the recess up to the level of the crosswise disposed part of the recess. By screwing the cap 120 ' onto the drive unit 100 ', the pin 131 ' enters the transverse portion of the recess from the end of the axial portion up to the end opposite thereto. As can be seen from fig. 7II, the lancet is also held axially by the holding device 132' by means of the pin, so that a guided puncturing movement can be carried out with the lancet. By the support of the pin on the transverse portion of the recess, not only the insertion of the needle tip but also the retraction of the needle tip can be performed with the lancet. As can be seen from fig. 7, the form-locking connection between the lancet and the holding device can be realized without clamping and locking. It is obvious that the principle of connection of the lancet to the drive plunger shown in fig. 7 can also be reversed, i.e. it is also possible to use corresponding retaining means on the lancet and retaining sections on the plunger or the drive.

Figure 9 shows a modified form of the system of figure 1. The drive ram 10 'has a retaining section 11' which has a circumferential inclined surface at its upper part, as shown in fig. 9B, which surface matches the inclined surface of the hooks 32a ', 32B' during piercing. When the elastic hooks 32a ', 32 b' are pressed together, the end of the drive plunger rests against the needle end, causing the bevel on the inner side of the hooks to press against the bevel on the upper part of the retaining section, pressing the retaining section against the needle end, and achieving a connection of the retaining section to the lancet without play in the puncturing direction. By means of this adaptation, a very precise form-locking fixation between the lancet and the drive plunger is achieved, which compensates for (manufacturing) tolerances, so that play is avoided both during the puncturing movement and during the retraction movement. It is also possible to design the retaining means in the form of hooks 32a ', 32b ' in such a way that the free ends of the hooks engage in the recesses of the sleeve 40 '. Thereby preventing the lancet 30 'from inadvertently protruding from the sleeve 40'. As can be seen from the transition from fig. 9A to fig. 9B, the free ends of the hooks are first released from the recesses at the beginning of the puncturing process, and then the hooks are pressed together during the insertion of the tapered sleeve, so that they engage around the retaining section of the drive rod.

As can also be seen in fig. 9, the needle tip 31' is arranged in a material 35. The material 35 is preferably an elastomer which tightly surrounds the needle tip so as to effectively prevent contamination of the needle tip. For suitable elastomers, one can consider: styrene block copolymers, thermoplastic polyolefins, thermoplastic polyurethanes, thermoplastic copolymers and copolyamides. For further details regarding this aspect of preventing contamination of the lancet tip, see international application WO 01/66010. In the initial position according to fig. a, the needle point is located in the spring body before piercing, which is pierced by the piercing when the piercing is performed, as shown in fig. B. The sleeve 40' has for this purpose a plate 36 with centring holes at its bottom. The plate prevents the elastomer from escaping from the bore, allowing the elastomer to be pierced as the needle passes out of the central bore. Upon retraction of the lancet, the elastomer remains on the needle and exposes the tip of the needle (see fig. C).

Fig. 10 shows a cartridge based on the lancet shown in fig. 1 or 9 in a cross-sectional view (fig. a) and in a perspective view (fig. B). With such a cassette, a new lancet can be connected to the drive device in a simple manner. For this purpose, the drive plunger can be arranged in a fixed position relative to a piercing aid, for example, and the cartridge shown in fig. 10 can be rotated like a revolver of a revolver, bringing an unused lancet into contact with the drive plunger.

Claims (14)

1. A device for drawing bodily fluid comprising:

a drive unit (100, 100') having a plunger (10, 110) which is moved from a rest position into a puncturing position for carrying out a puncturing procedure, and

a lancing unit (20, 120 '), in which there is a lancet (30, 130 ') with a needle which is located in the lancing unit when the push rod is in the rest position and which is moved by the push rod into the lancing position in such a way that the needle projects at least partially through an opening (41, 41 ') in the lancing unit,

wherein the push rod and the lancet are connected to one another by means of a form-fit connection in order to carry out the puncturing operation,

the form-locking is achieved by a retaining section (11, 131) of the push rod or of the lancet, which is held in a form-locking manner by a retaining device (32a, 32b, 132a, 132b) on the lancet or push rod, and

the retaining means on the lancet or push rod comprises a retaining element (32a, 32b, 132a, 132b) which is splayed when the lancet and push rod are not connected together,

wherein a longitudinal movement of the lancet parallel to the puncturing direction moves at least one holding element of the holding device transversely to the longitudinal direction, so that the holding elements move toward one another and at least partially enclose the holding section, a form-locking connection of the push rod and the lancet is achieved, the holding elements being closed when the lancet and the push rod are connected.

2. The device of claim 1, wherein the puncturing unit comprises a sleeve (40) in which the lancet is movably arranged.

3. The device of claim 2, wherein the sleeve has a passage in which the lancet moves, the passage having a taper by which the at least one movable element moves transversely to the direction of the piercing position when the lancet moves in the direction of the piercing position.

4. A device according to any one of claims 1-3, wherein the puncture unit is detachably fixed to the drive unit.

5. The device according to claim 4, wherein a form-locking connection of the push rod on the lancet is achieved when the puncturing unit is mounted on the drive unit.

6. A device according to claim 4, wherein the disengagement of the push rod from the lancet is achieved by removing the puncturing unit from the drive unit.

7. A device as claimed in claim 4, wherein the retaining means have at least two resilient elements which move towards one another when the push rod is connected to the lancet.

8. The device of claim 1 having an adjustment means for adjusting the extent to which the needle extends from the puncture unit.

9. The device as claimed in claim 1, having a magazine with a plurality of lancets which can be connected in turn to the push rod of the drive unit.

10. The device according to claim 1, wherein the holding device has two or more holding elements (132a, 132b) which are closed when the puncturing unit is placed on the drive unit, so that they hold the holding section of the lancet.

11. The device of claim 10, wherein said retaining elements are connected to a spring element that moves the retaining elements toward each other.

12. The device of claim 11, wherein said holding elements can be tensioned against the force of the spring element by means of a tensioning element, causing them to expand, placing the puncture unit on the drive unit to release the tensioning element, causing the holding elements to move towards each other.

13. A lancing unit (20) for mounting to a drive unit, comprising

A lancet (30) with a needle and a holding device with a holding element (32a, 32b) for producing a form-locking connection with the plunger of the drive unit, wherein the holding device is initially open, the holding element being moved transversely to the longitudinal direction when the lancet is moved longitudinally in a housing (40) of the puncturing unit.

14. A lancing unit according to claim 13, wherein the lancing unit has a sleeve (40) in which the lancet is arranged, the sleeve having a taper by which the holding device is at least partially closed when the lancet is inserted into the sleeve.