HK1105847B - Body fluid sampling device - Google Patents

Description

Body fluid sampling device

The present invention relates to the field of analyzing body fluids in order to make a diagnosis or to monitor the concentration of an analyte, such as the blood glucose concentration.

The present invention relates to a device or system for sampling small amounts of body fluid. A body fluid sampling device may include a skin piercing element with a fluid channel for receiving body fluid therein. At least a portion of the fluid channel is open to the environment. The sampling device further comprises a fluid receiving means separate from the fluid channel such that in the first (separate) state, fluid in the channel does not contact the fluid receiving means. The apparatus or system may transition into a second state in which at least part of the channel contacts the fluid receiving means, thereby transferring the fluid. Based on the signal from the sensor of the fluid receiving means, the analyte concentration can be determined.

Systems for sampling body fluids are known in the prior art, in which the body fluid is collected in a disposable element. Blood collection and analysis systems are known, for example from document EP 0199484, which comprise a disposable unit with capillaries to collect and transport body fluid into a detection zone. In WO 97/42888, a further development of this concept is described. The device described in this patent is particularly suitable for collecting relatively small amounts of body fluid, primarily by pressing the ring against the area surrounding the collection site and performing a suction movement. A system for analysis based on small amounts of interstitial fluid is known from EP 0723418. For this purpose, a very thin closed hollow needle is inserted into the dermis and interstitial fluid is transported through the needle to the test zone by applying pressure to the area surrounding the puncture site. From US 5,801,057 a highly miniaturized device is known which also uses a closed needle for extracting body fluid. A particular advantage of such an instrument is the extremely thin needle which can be inserted into the arm region of a patient substantially without any pain.

Although the appliance described in US 5,801,057 meets many practical needs, some features need improvement. A general problem with the sampling devices according to the previously mentioned documents is to manufacture the hollow needle in a cost-effective manner and to make the hollow needle as small as possible.

For this purpose, a body fluid sampler having an open fluid channel is contemplated. Documents US 2003/0018282 and US 2003/0028125 both describe skin piercing devices having an open channel at least partially in the area of the piercing needle for sampling body fluid. The body fluid sampled into the fluid channel is transferred to a test zone fixed to the skin piercing element. In particular, US 2003/0028125 describes that the skin piercing element is integral with a portion of the test strip. In US 2002/016290, other documents are described in which similar sampling and inspection devices providing a consensus are contemplated.

Prior art sampling and testing devices describe embodiments in which sample from a capillary channel is transferred directly to a test zone in contact with the channel. In contrast, the present invention proposes a body fluid sampling and testing device in which the fluid channel is not in fluid contact with the test zone during the phase of sample collection. After collection of the fluid sample into the fluid channel, at least part of the fluid channel is in contact with a fluid receiving means that receives fluid from the channel. The fluid receiving means may be a test zone, or it may be a zone where sample is transferred to the test zone. Thus, by the contacting step, in a controlled manner, the test zone can be brought into wetting. This trigger manner of wetting the test zone has the advantage that the reaction time (i.e. the time between contacting the test chemical with the sample fluid and reading the test result) can be controlled, which results in a more accurate analyte determination. A further advantage compared to prior art sampling devices is that the fluid sampling of the sampling device and the contact with the test zone can be performed at different locations. For example, fluid sampling may be performed at the front end of the hand-held instrument, while contact with the test zone may be performed within the instrument. Due to the shuttling function of the skin piercing element, the optical or other evaluation device may be moved into the interior of the housing, which is advantageous in view of the limited space at the front end. A further advantage of contacting the test zone or the fluid receiving means with the sample already in the fluid pathway is that it can be contacted with parts of the fluid pathway that do not contain the first fluid gushing from the body. By this advantage, the influence of plasma and substances from the body surface can be avoided or reduced.

Furthermore, physically separating the test zone from the blood during the sampling step avoids diffusion of test chemicals into the human body during sampling.

The present invention thus provides significant advantages over prior art fluid sampling devices.

One particular application area for systems and devices for drawing small amounts of body fluid is the so-called site-specific monitoring, in which the concentration of a particular analyte in a body fluid is determined at a particular time. Such measurements may be made repeatedly at certain time intervals in order to monitor changes in analyte concentration. Such an analysis using disposable test elements proves to be particularly advantageous, in particular in the field of blood glucose measurements by diabetic patients. If extremely high blood glucose values (hyperglycemia) occur in diabetic patients for a period of time, this can cause serious long-term damage such as blindness and gangrene. On the other hand, if the diabetic is in a hypoglycemic state, for example because he has injected an excessively large dose of insulin, this may be life-threatening in case the diabetic experiences a so-called hypoglycemic shock. Regular control of the blood glucose level enables the diabetic to avoid hyperglycemic and hypoglycemic states and also to learn how to coordinate his eating habits, physical activities and insulin medication. In addition to improving and maintaining the health of diabetic patients, regular blood glucose monitoring also has considerable overall economic advantages, since high costs for secondary diseases can be avoided. The reasons that prevent the more widespread and consequent use of blood glucose monitoring are mainly the pain caused by the required collection of body fluids and the multiple operating steps on the systems currently in the market. With the systems currently in use, a diabetic or medical professional must first obtain a drop of blood, which is typically obtained from a finger pad. So-called lancing devices can be used to reduce pain. The lancing device must first be loaded with the lancet, tensioned, placed on a body surface, and triggered. After the lancing process, the user has to squeeze his finger in order to carry a drop of blood out of the puncture wound. Before this process can be carried out, the diabetic has to place the test strip in the blood glucose measuring instrument and activate it. This drop of blood can now be applied to the test strip and, for example, after 10 seconds, a blood glucose measurement is available. Finally, the user has to dispose of the used lancets and test strips. The invention can simplify the process of measuring blood sugar.

A simplification is achieved by using a piercing element which receives a body fluid in the fluid channel and this fluid can then automatically come into contact with the fluid receiving means comprising the test zone. Not only is the simplification of blood glucose testing advantageous to current users, it also holds hopefully that more people with diabetes can regularly test their blood glucose concentration.

The sampling device and system according to the invention are used for extracting small amounts of body fluid. Body fluids in this connection are to be understood in particular as blood, interstitial fluid and mixtures of these body fluids. While in conventional blood collection systems this is typically done on the finger pad, the collection system according to the present invention may also be used to draw blood from alternative sites on the body, such as the forearm and palm.

The skin piercing element for extracting small amounts of body fluids according to the invention has a protruding portion with a sharp end for piercing the skin. A fluid channel having capillary activity for transporting body fluid is located in at least a region of the projection. At least part of the capillary structure, preferably the entire capillary, is open to the outside along its extension. Within the scope of the present invention, a capillary structure is understood as a body that transports body fluid to the proximal end of the capillary structure due to capillary forces when the distal end region is in contact with the body fluid. In terms of this function, the capillary structure according to the invention is similar to the open needle structure described in US 2003/0018282 and US 2003/0028125, which are incorporated herein by reference. However, it is important to distinguish that, in the microneedles described in these documents, the capillary grooves are in stable fluid contact with the test zone, so that the body fluid received in the capillary grooves is directly applied to the test zone, thus initiating the reaction.

The longitudinally extending portion of the skin piercing element extends from a proximal end providing the holding zone to a distal end having a protruding portion intended to be inserted into the skin. The prior art hollow needle has an opening at its distal end through which body fluid can enter, and the fluid pathway then changes to a closed channel or cavity within which the test zone is located. In contrast, the capillary structure according to the invention is preferably open to the outside over its entire longitudinal extension and the fluid passage is not closed by the test zone.

Open capillaries are produced by means of photolithography, as described in document US 5,801,057 and known from the field of semiconductor technology. Grooves, recesses, etc. open to the outside can also be provided in the solid needle by milling, etching and the like. Such a depression providing a capillary channel may lead from the tip or at least from the area of the tip abutting the skin piercing element to a proximal holding area connectable to the holding device. The depressions or capillaries need not necessarily extend in a straight line but may also be arranged, for example, in a spiral, curved, etc. Furthermore, the capillaries may be arranged in a network with branches, separate capillaries, or the like. The cross-section of the capillary may be, for example, V-shaped, semi-circular, or rectangular.

Such trenches are preferably formed by an etching process, such as photochemical milling (PCM). PCM is a method of machining metal structures without heating or mechanically milling the starting materials. PCM is based on optical pattern transfer and etching processes. It is known as a micro-machining technique.

The starting material is a metal sheet. The range of different materials that can be selected is broad, ranging from medical steel to aluminum and invar. In the case of steel, most of the standard medical types are available. The cost of raw steel is much lower when compared to silicon, glass or quartz.

PCM is a lithography-based fabrication method, i.e. the topography of the structure to be processed is transferred optically. The photopolymer is applied to the metal sheet as a film. Polymers are called photoresists and are of two types:

1. dried resist (foil laminated to substrate)

2. Wet resist (liquid spread and solidified on the substrate)

When the photoresist is selectively irradiated through the light-shielding member, the photoresist can be selectively removed from the substrate (this is generally referred to as patterning).

When the patterned substrate is exposed to an aqueous solution that reacts with the substrate material (e.g., ferric (III) chloride for steel), the material is selectively removed from areas where no photoresist remains (referred to as "etching"). There are two main principles of how the substrate can be brought into contact with the substrate.

1. Dipping a substrate into a bath of etchant

2. Spraying an etchant onto a substrate

The etching step is substantially isotropic in nature, i.e., the etch rate is approximately the same in all directions. During lithography, and during etching, isotropy can be affected by many parameters, and thus the etch profile can be controlled within certain limits.

Jet etching provides greater flexibility in controlling the etch rate and profile when compared to immersion etching.

In most cases, it is necessary that the photoresist layer be removed from the substrate to obtain a sampling device. The removal of the photoresist layer is typically a wetting process.

In addition to the already mentioned methods for incorporating the capillary groove into the surface, the capillary groove can also be formed by assembling the body in such a way that a capillary gap is formed. Thus, two or more solid needles may be fastened together, for example by welding, such that the contact areas of the solid needles form capillary grooves. In a corresponding manner, the wires may also be twisted together in the form of a twisted wire, so that a number of contact areas are formed which produce capillary grooves. Furthermore, a skin piercing element with a fluid channel may be formed by applying one or more layers of material (e.g. laminated foil) to a flat needle in such a way that a capillary gap is formed between the layers or provided in one such layer.

The capillary channel providing the fluid channel typically has a depth greater than the width. The ratio of depth to width (commonly referred to as the aspect ratio) is preferably 0.3 to 3. The cross-section of the capillary channel is typically greater than 2500 μm²And less than 1mm². Preferably, the capillary groove has a width in the range of 50 to 450 microns, and most preferably has a width of about 200 microns. As already stated above, it is advantageous if the capillary grooves are open on the outside, so that they can collect body fluid when the capillary structure is inserted into the body. For a good acquisition of body fluid, the area of the capillary structure which is open on the outside should have a length of 0.5mm or more.

The shape of the skin piercing element is relatively unimportant. For example, it may be in the form of a small cube. No special measures are usually required for mounting the skin piercing element in the drive unit, but preferably the holding area is located at the proximal end of the skin piercing element. Advantageously, the holding zone is integrally formed with the other areas of the skin piercing element. Known designs of piercing elements for disposable lancets of conventional blood sampling systems can be used. For example, the holding area may have a taper within which a spring element of a holder of the drive unit may engage in order to hold the piercing element. The piercing element is advantageously positioned within the holder in such a way that it allows a good control of the piercing depth (e.g. by pressing the end of the piercing element facing away from the tip against the stopper). Reference is made to document EP B0565970 in respect of such a holder and the interaction between the holder and the disposable lancing unit.

In addition to the skin piercing element, the body fluid sampling device also has a fluid receiving means spatially separated from the fluid channel of the skin piercing element so that fluid within the channel does not contact the fluid receiving means during priming. However, after the fluid sample is received within at least part of the fluid channel, and when it is desired to initiate an analytical reaction, the fluid receiving means and the channel come into contact with each other.

Having the skin piercing element spatially separated from the fluid receiving means makes it possible to use the skin piercing element as a shuttle to transfer the sampled fluid to the fluid receiving means. This is particularly advantageous when the fluid is sampled in a region which is confined to space, such as the front end of the instrument, and the fluid receiving means does not fit well into this confined space. In particular, the latter case is the case where the fluid receiving means is fixed to a belt, as described for example in european patent applications 02026242.4, US 4,218,421 and EP 0299517. The shuttle function enables the test procedure to be performed as follows:

piercing the skin with a skin piercing element

-sampling body fluid into a skin piercing element

-transferring the body fluid sampled by the skin piercing element to a fluid receiving device

Contacting the fluid receiving means with a body fluid on a skin piercing element

-detecting a change in the fluid receiving means related to the concentration of the analyte.

When using a cartridge with a fluid receiving means, the following steps may be included: exposing the particular fluid receiving means from the stored fluid receiving means to contact the skin piercing element loaded with the sample fluid. When a particular fluid receiving means is evaluated, other fluid receiving means may be exposed to contact the sample fluid on the skin piercing element.

Thus, a system according to the above shuttle concept has one or more skin piercing elements, a drive for driving the skin piercing elements to pierce the skin, and a transfer device for transferring the skin piercing elements into contact with the fluid receiving device. The drive member for piercing and the transfer device may be used in the same drive unit. Further, the system may comprise a reservoir unit for a plurality of fluid receiving devices. The system may further comprise an exposure unit for continuously exposing the fluid receiving means to receive the fluid.

The fluid receiving means has a structure that can collect fluid from the fluid channel of the skin piercing element. Such collection of fluid may be achieved, for example, by applying an electrical potential between the fluid located in the fluid channel and the fluid located in the fluid receiving means. Preferably, however, the fluid receiving means has a larger capillary action than the fluid channel of the skin piercing element, so that during contact fluid is automatically collected. In this regard, the fluid receiving means may be made of a fleece material or a textile material which has a large capillary action and is hydrophilic (at least in the region for collecting fluid). The fluid receiving means may have a particular area comprising such a material with a large capillary action, or the entire area of the fluid receiving means may serve as receiving means for fluid from the fluid channel. The fluid receiving means may itself be a test zone which may be covered with a fabric or woven material, or the fluid receiving means may be more complex and allow pre-processing of the sample fluid and/or transport of the fluid to the sensor/test zone. The pre-treatment may include filtering the fluid sample and/or mixing with reagents.

The fluid receiving means comprises a test zone with at least one layer of a chemical substance containing reagents for detecting the analyte.

The reagent undergoes a detectable change as a result of reaction with the analyte to be detected. For example, typical reagents for detecting glucose are based on glucose oxidase combined with a chromogenic redox system. In the prior art, reagents for optical evaluation that form a color with glucose from body fluids are well known. Furthermore, reagents from the field of blood glucose test strips are also known which allow electrochemical detection of analytes. The reagent mixtures used are generally in the solid state and, due to their composition (i.e. alumina, diatomaceous earth and the like), have such a large capillary action that they can collect body fluid from the capillary channel. Since these detection systems are well known from the prior art, they are not described in more detail here, but reference is made to US 5,762,770 and US 36,268.

The body fluid collection system according to the invention additionally has a drive unit which, when activated, moves the skin piercing element from the first position to the second position, thereby causing it to perform a lancing movement. Suitable drive units are well known from the field of blood sampling systems. For example, it may comprise a spring that is cocked by the user and that, when released, actuates the skin piercing element. In EP B0565970, a particularly advantageous drive unit is described.

A system/device for analyzing a body fluid comprises a detection unit. If a reagent-containing sensor/test zone is used that changes or develops color when an analyte is present, the system may have an optical detection unit that includes a light source and a detector to detect transmitted light or reflected light. When using electrochemical detection methods, the system has electrodes that contact the test zone or the fluid receiving means. For the evaluation of the primary signal, the system may have electronics known in the art for determining the concentration of the analyte, for example by measuring a so-called Cotrell current (see e.g. US 36,268).

With the skin piercing element according to the invention, it is possible to extract bodily fluids when the protruding part is inserted into the skin (i.e. to extract a sample directly from the body or from bodily fluids gushing out on the body surface), or after piercing, the protruding part can be withdrawn from the body and bodily fluids gushing out on the body surface can be collected. The partial extraction where the protruding portion remains in the body but the lancing channel in the skin is open for collection of body fluid is particularly suitable for sampling in the arm. This is due to the fact that the small incision in the arm closes very quickly so that no fluid, or only a very small amount of fluid, will spill out after the puncture. On the other hand, the sensitivity to pain on the arm is much less, for example when compared to the fingers, and thus, this does not cause pain when the projection is left in the body. As mentioned above, the open-sided capillary structure has the advantage that fluid can be collected via the open fluid channels, although the area for collecting the liquid through the hollow is limited by the front end of the needle. The latter is particularly disadvantageous when the opening of the needle is closed by tissue (due to the stamping of the tissue portion) during the puncturing process, so that no liquid, or only an insufficient amount of liquid, can be collected.

Furthermore, with the sampling device according to the invention, a decimation process can be performed, which is a combination of the previously mentioned processes. In this combined process, the piercing is performed first, pulling the projection back into the portion of the pierced pathway and allowing the projection to remain there for a collection period of a few seconds. The advantage of this procedure is that the protruding portion is retracted, which exposes a portion of the lancing channel, where bodily fluids are collected and from where they can enter the fluid channel of the skin piercing element. Furthermore, such a drawing process has the advantage that blood on the skin surface can be collected through the open channels. Depending on the situation, the residual blood can even be completely removed so that the user does not see any blood.

Other decisive factors that are important for efficient collection of body fluid into the fluid channel are the wettability of the capillary groove. When capillary structures made of silicon are used, these capillary structures are usually sufficiently wettable due to the silicon oxide layer on the surface. If metals are used for the capillary structures, these capillary structures are generally difficult to wet, relatively speaking. This can be eliminated by a number of different measures, such as silicidation of the surface. Wettability is usually sufficient when the liquid in the capillary has a concave meniscus at wetting angles of less than 90 °.

The invention is described in more detail with reference to the following drawings, in which:

FIG. 1 schematically shows a first embodiment of the invention with a moveable fluid channel in a perspective view;

FIG. 2 shows another embodiment with a movable fluid receiving device;

FIG. 3 shows another embodiment with a cutting portion passing through the piercing element and a test zone;

FIG. 4 illustrates the concept of electrically triggering contact of a sample fluid;

fig. 5 depicts a design for providing the skin piercing element and the test zone in separate geometries;

FIG. 6 schematically illustrates a modified shape of the capillary groove;

FIG. 7 shows a skin piercing element having areas with different cross-sections;

FIG. 8 schematically shows a cross-section of an embodiment for contacting with a magnetically triggered fluid;

FIGS. 9 and 10 schematically show cross-sections of embodiments with optical matching elements;

fig. 11 to 14 show top views of channel designs for additional fluid drainage.

Fig. 1 shows a skin piercing element (10) with a fluid channel (11), the fluid channel (11) extending within an extension (12, 13) of the skin piercing element. This part is connected to a holder (14) in the form of a frame. The extension portion has a protruding portion (12) protruding from a retainer portion (14). A sharp point (15) is located at the forward end of the projection. The sharp tip (15) is capable of penetrating the skin surface during lancing with the skin piercing element. The fluid channel (11) starts in the front end area of the protruding part and extends into a movable part (13) located in a holder frame (14). The fluid channel is an open capillary channel which, by capillary action, allows body fluid contacting the channel in the area of the protruding portion to move into the displaceable portion (13). As depicted in fig. 1A, the protruding portion, the movable portion and the frame portion of the skin piercing element are integrally formed. The skin piercing element (10) may be manufactured by an etching process. As is well known in the silicon manufacturing process, a wafer of silicon material may be etched to provide a device including tips and capillary grooves. However, for mass production it is advantageous to produce the skin piercing elements by etching a thin metal plate. It is particularly advantageous that the sharp point (15) of the projection (12) can also be formed during the etching process, so that a separate grinding step is avoided.

As can be seen from fig. 1A, there are no reagents or sensors contacting the fluid channel that can receive body fluid immediately after the channel is filled with sample fluid. In contrast, the invention proposes to locate the test zones or sensors on the fluid receiving means in a separate manner.

Fig. 1B shows the skin-piercing element (10) of fig. 1A together with a fluid receiving device comprising a test zone. A fluid receiving means (40) is schematically shown. The fluid receiving means (40) is located on the upper side of the skin piercing element, on which upper side the fluid channel (11) is open to the environment. However, the fluid receiving means (40) is initially separate from the fluid channel (11) such that sample fluid within the fluid channel does not contact the fluid receiving means. Thus, within this geometry of the fluid sampling device, no fluid is transferred from the fluid channel to the fluid receiving means. In the depicted embodiment, the fluid receiving device basically comprises a holding structure (41) and a test zone (45) providing a proper orientation and spacing of the fluid receiving device with respect to the skin piercing element. In the depicted embodiment, the test zone is a reagent chemistry that generates an optical signal based on the concentration of the analyte within the body fluid. By incorporating porous materials such as diatomaceous earth or titanium dioxide, the reagent chemicals already have a large capillary action to draw fluid from the capillary channel (11). Reagent chemicals are applied to the carrier surface. As shown in fig. 1B, the fluid pathway and the test zone (45) are initially separated so that body fluid located within the capillary channel (11) is not transferred to the test zone (45). After the fluid is received in the fluid channel and the movable section (13) is filled, the body fluid sampling device is ready for measurement. By mechanical actuation, the movable section (13) can be bent in the direction of the sensor (45) so that the body fluid located in the fluid channel contacts the test zone and wets the reagent chemistry. This mode of bringing the sensor into contact with the sample fluid has several advantages over prior art devices.

A first advantage over the prior art is that the measurement can be started at a specific point in time. This means that the time between wetting the test zone and measuring the final signal can be chosen at will. However, the time period is shorter than the drying time of the blood in the capillary. Knowing or controlling the time of the reaction provides accuracy of the measurement. Furthermore, the measurement of the signal can be started immediately after wetting, which allows monitoring of the reaction dynamics. The evaluation of this early signal can also be used to improve the accuracy of the measurement results. From fig. 1B, another advantage can be seen. When the movable section (13) is in contact with the test zone (45), it contacts the middle section of the fluid channel (11) and does not just contact the ends. Fluid contaminated by the skin surface or containing interstitial fluid (ISF) first enters the capillary and therefore, after filling, remains within the end portion of the capillary. The fluid in this end portion does not come into contact with the fluid receiving means and therefore the end portion is called a discharge area. Thus, the middle portion of the channel contains fluid that is nearly uncontaminated and free of ISF. This area is called the access area since fluid from this area is transferred to the fluid receiving means and thus needs to be accessible. This concept of transferring fluid from the capillary tube to the fluid receiving means serves to exclude interference of plasma or substances from the skin surface with the measurement. Of course, contamination by substances from the skin surface should be avoided if possible, especially when the amount of sample used for analysis is reduced to low amounts (e.g. below 1 microliter). For interstitial fluids, it is known that such body fluids do not normally show the current blood glucose concentration, but show concentrations from 5 to 30 minutes ago. This is due to the time delay of the exchange between the blood compartment and the interstitial fluid compartment.

It will be appreciated that this concept of avoiding contacting the fluid receiving means with the (contaminated) fluid first received in the channel may be applied to many device designs and is not constrained by sampling devices having skin piercing elements. This involves a method of sampling a fluid comprising the steps of:

-introducing a fluid into an introduction region of a support structure having a trench therein, said fluid filling an access region of the support structure accessible from the surroundings, and the trench having a discharge region downstream of the access region

-contacting the fluid receiving means with the fluid located in the access region to receive the fluid but not to contact it with the fluid in the discharge region.

Returning now to the embodiment shown in fig. 1, wherein the support structure is a skin piercing element. In fig. 1C, the contact between the movable part (13) and the sensor (45) can be seen. As this figure shows, the movable part can be bent upwards, since it is in the form of a tongue. Due to the very thin construction of the skin piercing element, the movable section may automatically have sufficient flexibility if the skin piercing element is made of a ductile material. Suitable materials are, for example, metals, silicon, or even ceramics which do not crack when bending occurs.

It is contemplated that instead of having the capillary reach the test zone, the test zone may also reach the capillary, for example by bending the carrier.

Fig. 2 shows a second embodiment, in which the contact between the fluid channel and the fluid receiving means is achieved by means of a movable fluid receiving means. As in the first embodiment, the skin piercing element has a protruding portion (12) with a tip (15) for piercing the skin. A fluid channel (11) in the form of a capillary channel starts near the piercing tip (15) and extends into the middle section of the holder portion (14). The fluid receiving means comprises a spacer (42) and a movable carrier (43) fixed to the spacer. The movable carrier (43) holds on its underside a test zone (45) in the form of a reagent matrix for carrying out optical detection. When the capillary channel (11) is filled with sample fluid, the movable carrier (43) is pressed down and the test zone (45) contacts the filled channel and collects body fluid. The transparent carrier (43) can now be irradiated and the radiation reflected by the rear side of the test zone (45) can be measured to obtain a signal.

Fig. 2B shows in more detail the portion of the fluid channel (11) that contacts the sensor (45). As can be seen, the channel has upstanding walls projecting from the upper surface of the skin piercing element (14). The upstanding wall (11') has sharp edges. The function of these edges can be better seen in fig. 2C, which shows the interaction between the test zone and the fluid channel (11). The left panel of fig. 2C shows the test zone (45) in proximity to the fluid pathway. The test zone (45) is located on the underside of the carrier (40). The body fluid (25) remaining in the fluid channel (11) has a downward-pressing conical shape. This means that a slight contact between the test zone and the wall of the fluid channel may not be sufficient to bring the body fluid into contact with the test material. In the right picture the function of the sharp edge can be seen, which is used to press down the sensor material, or even to cut it. Due to this function, on the one hand, the test zone is closer to the surface of the body fluid, while on the other hand, an intimate contact between the test material and the walls of the groove is achieved. Both of these aspects improve the transfer of body fluid from the fluid channel to the test zone strip.

Fig. 3 depicts four embodiments showing the cutting portion and the test zone passing through the piercing element. This illustrates the technical difficulties that have to be taken into account. In fig. 3A, in the embodiment shown, a hydrophobic coating (16) is applied on the body piercing element that is located beside the fluid channel. As can be seen in fig. 3A, the contact of the test zone with the skin-piercing element not only brings the test zone into contact with the body fluid, but also during the contact a capillary space is formed between the test zone (or carrier) on the one hand and the part lying on the other hand beside the fluid passage. This generally creates a large capillary action that transfers the sample fluid in the channel not only to the test zone strip but also to the small capillary space created. The hydrophobic coating (16) avoids sample fluid from spreading between the upper surface of the skin piercing element (14) and the carrier or test zone. It is desirable to transfer the sample to a dedicated zone of test material so that the amount of transferred sample fluid is sufficient to wet the test zone in a manner that an accurate measurement can be made. Loss of sample fluid to other areas of the test zone or to the carrier may mean that, in dedicated areas, the test material is not sufficiently wetted and appropriate measurements cannot be made.

Fig. 3B shows another embodiment that avoids accidental spreading of the sample fluid. Similar to fig. 2, this embodiment has upstanding trench walls that contact the test zones or carriers. Due to this, the fluid spreading into the space stops at the outer trench wall and the loss of sample fluid is greatly reduced. However, the trench walls need not be square as depicted in fig. 3B, they may also be sharp as shown in fig. 3C or 3D.

Fig. 4 shows the concept of electrically triggering the contact of the sample fluid with the test zones. However, in fig. 4, this general concept is shown with respect to a skin piercing element as a specific embodiment of a support structure with grooves. For fluidic triggering, a high electrical potential is applied between the sample fluid (25) and the carrier (40). This may move the sample fluid from the channel to the test zone, or may move the carrier in the direction of the channel. In both cases, by switching on the potential, the wetting of the test zones by the sample fluid can be triggered in a very short time period. As can be seen by the picture of the transparent carrier, the grooves below the test zone open into a collection zone (26) to provide a larger amount of fluid for wetting the test zone than can be provided by the fine capillary grooves.

FIG. 4B depicts a preferred embodiment of the collection zone in more detail. As can be seen, the collection zone (26) preferably has upstanding elements (26') that assist in moving fluid to the test zone. On one hand, these upstanding elements induce a high electrical charge at their ends for transporting the fluid, and on the other hand they increase the capillary action of the collection zone (26), which improves the priming of the fluid.

Fig. 5A, B and C depict sampler designs for providing the skin-piercing element and the test zone in separate geometries that allow the test zone to be brought into contact with the sample fluid within the channel by actuation. The embodiment of fig. 5A is similar to that of fig. 1. The skin piercing element comprises a frame connected to an inner portion (13 '), the capillary channel (11) extending within the inner portion (13'). The inner part and the frame are connected by a bendable part (51). After the capillary channel is filled, the inner portion is twisted against the frame so that a portion of the capillary contacts the test zone beneath the carrier (43). By bending around the bendable portion, the inner portion contacts the test zone in an angled manner. This proves to be particularly advantageous, since it provides a uniform wetting of the test zones without the inclusion of air bubbles.

Fig. 5B shows an embodiment where the carrier (43) and its support are connected to the main part (14 ') comprising the capillary via a bendable part (51'). Again, in an inclined manner, contact between the capillary and the test zone is achieved.

Fig. 5C shows an embodiment with an inner part (13 ") connected at both ends to a frame part (14"). When pressure is applied to the central part of the inner part (13 ") from the underside, this inner part (13") bends against the test zone strip below the carrier (43). Again, by arching this inner portion, an angled contact is achieved.

Figure 6 schematically depicts the shape of the modified capillary groove. It has been found that the fill level of the fluid within the channel generally increases as the width of the channel decreases. The capillary of fig. 6 has a first region (a) leading into the tip portion of the skin piercing element. The second region (b) of increased diameter serves to increase the sample volume. Particularly useful is the third region (c) of reduced width. As the width decreases, the fill level increases and therefore the transfer of fluid from the channel to the test zone has a large success rate. It is therefore preferred that the test zone is brought into contact with the capillary in an inclined manner such that it contacts region (c) first and, after that, region (b). This ensures that fluid transfer is safely initiated through region (c) and that sufficient sample is provided for testing through region (b). Zone (d) downstream of zone (c) may be used to discharge contaminated sample fluid or ISF.

Fig. 7 shows a skin piercing element with a first area (a) leading into the tip area and a second area (b) of increased diameter. Panel a shows the situation after piercing the skin and collecting blood into the area (a) of the capillary groove. Due to the lower capillary action of zone (b), the sample liquid fills zone (a) but not zone (b). When the skin piercing element is in contact with the carrier (43), the open channel structure (a, b, d) in some parts is closed at its top, so that the capillary action in this part increases, filling the collection area (b) and bringing the test zone on the underside of the carrier (43) into contact with the sample fluid. Advantageously, in view of the geometry of the optical element, there is a circular detection zone.

In the following way, the skin piercing element according to fig. 7 can be used:

piercing the skin

-sampling body fluid into a portion (area (a)) of the capillary groove

Contacting the capillary channel in the collection area (b) with the test zone and/or the carrier, whereby the area (b) is filled with body fluid

-detecting a change in the test zone due to a reaction with the analyte from the body fluid.

In the concept shown in fig. 8, contact between the sensor 45 and the fluid channel or groove 11 may be established by using a magnetic force 70. Paramagnetic or ferromagnetic material 72 is incorporated into, mounted to, or attached to the sensor or channel portion 13. Alternatively, a current carrying wire of suitable geometry is incorporated into or attached to the sensor or the channel portion.

Thus, a magnetic field 72 provided by an electromagnet 74 (or a permanent magnet, solenoid, or other suitable device) exerts an excitation force 70 on the sensor (or the channel portion or both) causing them to come into fluid contact. By controlling the magnetic field strength, i.e. by switching electromagnet 74 or close to the permanent magnet, the force and thus the time-dependent triggering of the fluid contact is controlled.

Furthermore, by means of a time-varying magnetic field at the ring, a magnetic dipole moment can be induced in the non-magnetic ring (or similar geometry) placed on the sensor or the trench section. This is an alternative way of generating the energizing force for the triggered fluid contact.

As shown in fig. 9 and 10, the optical index matching element 80 serves to link the test zone (sensor 45) of the fluid receiving means 82 to an optical detection unit (not shown) and at the same time to exert a mechanical force to bring the fluid channel 11 and the sensor 45 of the fluid receiving means 82 into contact.

As outlined above, the glucose concentration is determined by dynamic measurement of the color change within the sensor 45 when wetted with a sufficiently large amount of blood contained within the channel or trench 11. Reflectometry measurements are made by illuminating sensor 45 with incident light of an appropriate wavelength and detecting reflected radiation 86.

In the case of an optical detection system, the limited detection zone on the sensor 45 severely constrains the mechanical positioning tolerances of the wetted test zones. Furthermore, if only a small detection zone is available, the inhomogeneity in the sensor enzyme chemistry more severely affects the coefficient of variation for repeated glucose measurements. At the same time, the triggered excitation between the blood and the sensor 45 is optically detected, which makes it necessary that there is no interference between the trigger excitation mechanism and the optical detection system.

An optical system comprising suitable light emitters and receivers and optical devices such as lenses and/or optical fibers is used for performing reflectometry measurements. The amount of light of a certain wavelength reflected from the sensor 45 gives a measurement of the glucose concentration.

The sensor 45 typically comprises enzymatic chemicals mixed with small particles that diffusely reflect incoming light, which are mounted on a polycarbonate strip or foil 82, with well-defined optical transmission properties. The illuminating light 84 is diffusely scattered by the particles within the strip and absorbed by the dye activated by the enzymatic reaction with blood glucose. Thus, the amount of reflected light 86 decreases as absorption increases with increasing glucose concentration.

The elastomeric optical element 80 has a refractive index that closely matches the refractive index of the sensor 45. The element 80 acts as an intermediate layer or plate between the sensor 45 and the optics of the detection unit. The element 80 may have means 88 that allow the element 80 to act as a lever arm for converting the mechanical displacement into a triggered actuation of the sensor 45 (see fig. 9). The sensor 45 abuts the element 80 on one side thereof, while the opposite site of the sensor is separated from the trench 11 by a spacer 90, which maintains a free air gap 92. When activated, the fluid receiving means 82 flexes downwardly and blood within the microchannel 11 beneath the sensor 42 is transferred to the sensor and a dynamic color change reaction occurs.

Thus, the above-mentioned members:

means are provided for the activation element to face the channel 11 for triggered blood sensor contact;

allowing simultaneous illumination of the sensor 45 and collection of the reflected light intensity;

allowing optical detection of small sensor areas;

-reducing interference from fresnel reflections at the sensor surface.

Alternatively, as shown in FIG. 10, an optical waveguide/fiber assembly 94 in combination with an intermediate matching element 80 is used to illuminate the sensor 45 and to collect reflected light, while the waveguide/fiber 94 is used to displace the element 80, thus bringing the sensor 45 against the fluid channel or groove 11. The optical waveguide/fiber 90 may also directly excite the sensor 45 if the index matching element is provided with a specific coating.

The optical waveguide/fiber bundle 94 is mechanically excited by an excitation mechanism (a motor or other drive unit or mechanism that translates micro-sampler movement into displacement of the optical waveguide/fiber). The intermediate elastomeric material 80 translates the mechanical displacement of the optical fiber or other mechanical actuator directly to the sensor 45, thereby acting as a mediator for triggered excitation/contact between the sensor 45 and the adjacent portion of the blood-filled microfluidic channel 11.

In addition, the bundle 94 of small diameter fibers 96 is used to locate a small area on the sensor 45 since the cone of light acceptance for each individual fiber 96 within the bundle is limited by its numerical aperture. Thus, densely packed fiber bundles are used to sample discrete small areas on the sensor. Some fibers may actually sample the portion of the detection zone on the sensor that is wetted, while other fibers sample the portion that is not wetted. The fiber bundle may be coupled to a detector array or CCD for individual reading of the fibers, thus producing an image of the detection zone. Sampling the fibers individually enables detection in a small sensor area while greatly mitigating mechanical positioning tolerances.

Each individual fiber may be positioned to illuminate the sensor or to collect diffusely reflected light, or both if a suitable beamsplitter is used. A random distribution of fibers within the bundle is desirable to provide uniform illumination of the sensor and to provide complete detection coverage of the sensor surface.

Fig. 11 shows an example for a body fluid sampling device, in which a laterally open capillary channel 11 has a sampling section 100 and a discharge section 102 that branches off upstream of the sampling section to collect the part of the body fluid that enters the capillary tube first at a tip region 104. Again, this allows for the venting of contaminated sample fluid or ISF, as explained above with respect to fig. 6. In order to receive the first portion of fluid, it is necessary that the capillary action of the discharge section 102 is higher than the capillary action of the inlet section 106 in the bifurcated region 108. To increase capillary action, the discharge section 102 may be closed by a cap 110. In this case, it is important that the outlet 112 is open at the end of the discharge section.

Fig. 12 depicts an embodiment in which the discharge section extends to include a waste region 114 and a receptacle region 116 upstream of the waste region. Since the opening is wide, the sampling or destination section 100 is not filled during the acquisition phase. Only during the contact phase, in which the sensor 118 is in contact with the sampling section 100 and closes this area as a cap, does the capillary action increase and blood is drawn from the container area 116 into the sampling section 100. Thus, it is necessary that the volume of the discharge section is large enough to enable the sampling section 100 to be filled and additionally to collect waste fluid.

As shown in fig. 13, to speed up the loading of the sampling section, multiple discharge sections 102 may be used. Different cross-over configurations 120 may be used to direct the fluid under capillary action (fig. 14).

Claims (78)

1. A device for sampling a bodily fluid, comprising:

a fluid channel (11) for receiving a body fluid in a separated state, wherein at least part of said fluid channel (11) is open to the environment along its longitudinal extension; and

a fluid receiving means (40) separately spaced from said fluid passageway (11) such that in a separated state, bodily fluid in said fluid passageway (11) is not in fluid contact with the fluid receiving means (40);

when activated, the device is adapted to undergo a physical change, thereby assuming a contact state in which fluid in said fluid channel (11) contacts said fluid receiving means (40);

wherein the device has a movable part (13) which can be moved and at least part of the fluid channel (11) or the fluid receiving means (40) is located on the movable part (13) to assume a contact state.

2. The device according to claim 1, further comprising a skin piercing element (10) having said fluid channel (11).

3. Device according to claim 1, wherein the fluid receiving means (40) comprises a test zone (45).

4. The apparatus according to claim 1, wherein the fluid receiving means (40) is separated from the fluid channel (11) by an air gap (92).

5. The apparatus according to claim 4, characterized in that the air gap (92) is maintained by a spacer (90).

6. The device according to claim 2, wherein said skin piercing element (10) has a fluid transfer zone and at least a portion of said fluid channel (11) within said fluid transfer zone has a sharp wall (11').

7. An apparatus according to claim 6, characterized in that said fluid receiving means (40) comprises a layer structure which can be pressed or cut by said sharp wall (11').

8. Device according to claim 1, characterized in that the body fluid received in the fluid channel (11) is moved onto the fluid receiving means (40) by activation with electricity.

9. Device according to claim 2, characterized in that the skin piercing element (10) has a collecting zone (26), the upright element (26') being located within the collecting zone (26).

10. The apparatus according to claim 1, characterized in that the fluid channel (11) or the fluid receiving means (40) has a defining means for defining a region of fluid transfer from the fluid channel (11) onto the fluid receiving means (40).

11. The device according to claim 1, characterized in that the fluid channel (11) has a protruding wall portion and that the surface adjacent to the fluid channel (11) is recessed with respect to the protruding wall portion.

12. The device according to claim 1, wherein the surface adjacent to the fluid channel (11) is hydrophobic.

13. Device according to claim 1, wherein said fluid receiving means (40) comprises a test zone (45) and further comprises at least one of a reaction zone, a filtration zone and a mixing zone.

14. Device according to claim 2, wherein said skin piercing element has two or more fluid channels (11).

15. The apparatus according to claim 1, wherein the fluid channel (11) has a first width in a first region (a) and a second width smaller than the first width in a further region (c).

16. Device according to claim 1, wherein said fluid passage (11) further comprises a collection zone (b).

17. Device according to claim 3, wherein the test zone (45) is located in or in contact with an intermediate portion of the fluid passage (11) such that the portion of the fluid which first enters the fluid passage is not in contact with the test zone (45).

18. Device according to claim 1, wherein the fluid channel (11) has a sampling section (100) and at least one discharge section (102) downstream of the sampling section (100) and/or diverging upstream of the sampling section (100) for receiving the part of the body fluid which enters the fluid channel (11) first, and wherein the sampling section (100) is the test zone (45) or can be brought into contact with the test zone (45) for analyzing the body fluid contained therein.

19. Device according to claim 18, characterized in that the fluid channel (11) is an open capillary channel, through the inlet section (106) of which the sampling section (100) is filled, the capillary action of the inlet section (106) being smaller than the capillary action of at least one discharge section (102) branching off from the inlet section.

20. The apparatus of claim 18, wherein the capillary action of the discharge section (102) is increased by closing an open side portion of the discharge section (102) with a cap (110).

21. The apparatus according to claim 18, wherein the discharge section (102) has a waste region (114) and a container region (116) upstream of the waste region (114), and wherein, after the collection phase, the body fluid from the container region (116) is supplied to the sampling section (100).

22. The apparatus according to claim 18, wherein the capillary action of the sampling section (100) is increased by contacting the fluid receiving means (40) after filling the discharge section (102).

23. The apparatus of claim 18, wherein the volume of the discharge section (102) is greater than the volume of the sampling section (100).

24. A device according to claim 3, comprising a meter with a detection unit for receiving signals from said test zone (45) to determine the presence of an analyte and/or to determine the concentration of an analyte.

25. Apparatus according to claim 24, wherein the meter comprises a holder in which the fluid receiving means (40) is received and in which signals can be transmitted from the test zone (45) to the detector.

26. Device according to claim 24, comprising contacting means for contacting a portion of the fluid pathway (11) with the fluid receiving means (40) for providing the test zone (45) with sample fluid.

27. Device according to claim 26, wherein the meter has a processing unit which receives a signal indicating that the contacting means has contacted the fluid pathway (11) with the fluid receiving means (40) or that the sample fluid has reached the test zone (45).

28. Apparatus according to claim 26, wherein said contacting means comprises voltage means for applying an electrical potential between said fluid pathway (11) and said fluid receiving means (40) such that fluid from the fluid pathway (11) contacts the fluid receiving means (40).

29. An apparatus according to claim 26, wherein the contacting means applies a force to the movable part (13) of the fluid channel (11) or the fluid receiving means (40) to bring the fluid channel (11) and the fluid receiving means (40) into contact with each other.

30. Apparatus according to claim 1, comprising magnetic contacting means (74, 76) for applying a magnetic field (72) for bringing the fluid channel (11) and the fluid receiving means (40) into fluid transferring contact.

31. An apparatus according to claim 30, characterized in that the magnetic contact means (74, 76) comprises a permanent magnet, an electromagnet (76), a solenoid or a wire carrying an electric current.

32. Apparatus according to claim 30, characterized in that at least one of paramagnetic or ferromagnetic material (74) or an element carrying an electric current or an element, preferably a ring-shaped element for generating a magnetic dipole moment under a time-varying magnetic field is incorporated in or attached to a part of the fluid channel (11) and/or the fluid receiving means (40).

33. Device according to claim 26, characterized in that the contacting means have an optical matching element (80) for linking the test zone (45) to the optical detection unit, the optical matching element (80) being adapted to exert a mechanical force to bring the fluid channel (11) and the fluid receiving means (40) into a contacting state.

34. The device according to claim 33, characterized in that the optical detection unit comprises a reflectometer connected to the optical matching element (80) via optical means comprising lenses, optical waveguides and/or optical fibers (94).

35. Device according to claim 33, characterized in that the optical matching element (80) is provided with a coating of the optics facing the examination zone (45).

36. The device according to claim 33, characterized in that the optical matching element (80) has a refractive index that matches the refractive index of the examination zone (45).

37. The apparatus according to claim 33, wherein the optical matching element (80) comprises an elastomeric material.

38. Device according to claim 33, characterized in that the optical matching element (80) is arranged on the side of the test zone (45) opposite the fluid channel (11) and is preferably designed as a lever arm or a push rod for converting a mechanical displacement to assume a contact state between the fluid channel (11) and the test zone (45).

39. Device according to claim 2, comprising driving means for driving the skin piercing element (10) into the skin for piercing the skin for obtaining the body fluid sample.

40. A device for sampling a bodily fluid, comprising:

a fluid channel (11) for receiving a body fluid in a separated state, wherein at least part of said fluid channel (11) is open to the environment along its longitudinal extension; and

a fluid receiving means (40) separated from said fluid channel (11) by an air gap (92) such that in a separated state, body fluid in said fluid channel (11) is not in fluid contact with the fluid receiving means (40);

when activated, the device is adapted to undergo a physical change, thereby assuming a contact state in which fluid in said fluid channel (11) contacts said fluid receiving means (40);

wherein the body fluid received in said fluid channel (11) is moved onto the fluid receiving means (40) by activation with electricity.

41. The device according to claim 40, further comprising a skin piercing element (10) having said fluid channel (11).

42. Apparatus according to claim 40, wherein the fluid receiving means (40) comprises a test zone (45).

43. The apparatus of claim 40, wherein the air gap (92) is maintained by a spacer (90).

44. A device according to claim 41, wherein said skin piercing element (10) has a fluid transfer region and at least a portion of said fluid channel (11) within said fluid transfer region has a sharp wall (11').

45. An apparatus according to claim 44, wherein said fluid receiving means (40) comprises a layer structure which can be depressed or cut by said sharp wall (11').

46. An apparatus according to claim 40, wherein the body fluid received in said fluid channel (11) is moved onto the fluid receiving means (40) by activation with electricity.

47. Device according to claim 41, characterized in that the skin-piercing element (10) has a collection zone (26), the upright element (26') being located within the collection zone (26).

48. Apparatus according to claim 40, wherein the fluid channel (11) or the fluid receiving means (40) has a defining means for defining a region of fluid transfer from the fluid channel (11) onto the fluid receiving means (40).

49. The apparatus according to claim 40, wherein the fluid channel (11) has a protruding wall portion and the surface adjacent to the fluid channel (11) is recessed with respect to the protruding wall portion.

50. The apparatus according to claim 40, wherein the surface adjacent to the fluid channel (11) is hydrophobic.

51. Apparatus according to claim 40, wherein said fluid receiving means (40) comprises a test zone (45) and further comprises at least one of a reaction zone, a filtration zone and a mixing zone.

52. An apparatus according to claim 41, wherein said skin piercing element has two or more fluid channels (11).

53. The apparatus according to claim 40, wherein the fluid channel (11) has a first width in a first region (a) and a second width smaller than the first width in a further region (c).

54. Apparatus according to claim 40, wherein said fluid pathway (11) further comprises a collection zone (b).

55. Device according to claim 42, wherein the test zone (45) is located in or in contact with an intermediate portion of the fluid channel (11) such that the portion of the fluid which first enters the fluid channel (11) is not in contact with the test zone (45).

56. Device according to claim 55, wherein the fluid channel (11) has a sampling section (100) and at least one discharge section (102) downstream of the sampling section (100) and/or diverging upstream of the sampling section (100) for receiving the part of the body fluid which enters the fluid channel (11) first, and wherein the sampling section (100) is the test zone (45) or can be brought into contact with the test zone (45) for analyzing the body fluid contained therein.

57. Device according to claim 56, characterized in that the fluid channel (11) is an open capillary channel, through the inlet section (106) of which the sampling section (100) is filled, the capillary action of the inlet section (106) being smaller than the capillary action of at least one discharge section (102) diverging from the inlet section.

58. The apparatus of claim 56, wherein the capillary action of the discharge section (102) is increased by closing an open side portion of the discharge section (102) with a cap (110).

59. The apparatus according to claim 56, wherein the discharge section (102) has a waste region (114) and a container region (116) upstream of the waste region (114), and wherein, after the collection phase, the body fluid from the container region (116) is supplied to the sampling section (100).

60. The apparatus according to claim 56, wherein the capillary action of the sampling section (100) is increased by contacting the fluid receiving means (40) after filling the discharge section (102).

61. The apparatus of claim 56, wherein the volume of the discharge section (102) is greater than the volume of the sampling section (100).

62. Device according to claim 42, comprising a meter with a detection unit for receiving signals from said test zone (45) for determining the presence of an analyte and/or for determining the concentration of an analyte.

63. Apparatus according to claim 62, wherein the meter comprises a holder in which the fluid receiving means (40) is received and in which signals can be transmitted from the test zone (45) to the detector.

64. Apparatus according to claim 62, comprising contacting means for contacting a portion of the fluid pathway (11) with the fluid receiving means (40) for providing the test zone (45) with sample fluid.

65. An apparatus according to claim 64, wherein the meter has a processing unit which receives a signal indicating that the contacting means has contacted the fluid pathway (11) with the fluid receiving means (40) or that the sample fluid has reached the test zone (45).

66. Apparatus according to claim 64, wherein said contacting means comprises voltage means for applying an electrical potential between said fluid pathway (11) and said fluid receiving means (40) such that fluid from said fluid pathway (11) contacts said fluid receiving means (40).

67. An apparatus according to claim 64, wherein the contacting means applies a force to the movable part (13) of the fluid channel (11) or the fluid receiving means (40) to bring the fluid channel (11) and the fluid receiving means (40) into contact with each other.

68. Apparatus according to claim 40, comprising magnetic contacting means (74, 76) for applying a magnetic field (72) for bringing the fluid channel (11) and the fluid receiving means (40) into fluid transferring contact.

69. An apparatus according to claim 68, characterized in that the magnetic contact means (74, 76) comprise a permanent magnet, an electromagnet (76), a solenoid or a wire carrying an electric current.

70. Apparatus according to claim 68, characterized in that at least one of paramagnetic or ferromagnetic material (74) or an element carrying an electric current or an element, preferably a ring-shaped element for generating a magnetic dipole moment under a time-varying magnetic field is incorporated in or attached to a part of the fluid channel (11) and/or the fluid receiving means (40).

71. Device according to claim 64, characterized in that the contacting means have an optical matching element (80) for linking the test zone (45) to the optical detection unit, the optical matching element (80) being adapted to exert a mechanical force to bring the fluid channel (11) and the fluid receiving means (40) into a contacting state.

72. The device according to claim 71, characterized in that the optical detection unit comprises a reflectometer connected to the optical matching element (80) via optical means comprising lenses, optical waveguides and/or optical fibers (94).

73. The device according to claim 71, characterized in that the optical matching element (80) is provided with a coating of the optics facing the examination zone (45).

74. The device according to claim 71, characterized in that the optical matching element (80) has a refractive index that matches the refractive index of the examination zone (45).

75. The device according to claim 71, wherein the optical matching element (80) comprises an elastomeric material.

76. Device according to claim 71, characterized in that the optical matching element (80) is arranged on the side of the test zone (45) opposite the fluid channel (11) and is preferably designed as a lever arm or a push rod for converting a mechanical displacement to assume a contact state between the fluid channel (11) and the test zone (45).

77. A device according to claim 41, comprising driving means for driving the skin piercing element (10) into the skin for piercing the skin for obtaining the body fluid sample.

78. Method for transferring a fluid from a support structure to a fluid receiving device (40), comprising the steps of:

maintaining a support structure having a channel accessible from the surroundings in at least an access region for receiving fluid therein in spaced relation to a fluid receiving means (40);

applying an electrical potential between the fluid in said access region and said fluid receiving means (40) so that fluid from said access region is transferred to said fluid receiving means (40).