US20110092854A1 - Instruments and system for producing a sample of a body fluid and for analysis thereof - Google Patents

Abstract

An instrument for producing a sample of body fluid for analysis by piercing the skin with a lancing element having a piercing tip is disclosed. The instrument can comprise a housing and a lancing drive for driving a lancing element connected thereto in a puncturing movement. A pressure ring can surround a skin contact opening and can be adapted for pressing against the skin such that the skin can bulge into the skin contact opening for promoting expression of body fluid. The skin contact opening can have a circular opening with a diameter of at least about 3 mm and at most about 8 mm. The instrument can comprise a pressing force control device for controlling the pressing force between the pressure ring and the skin at the time of triggering the puncturing movement, to be at least about 3 N and at most about 8 N.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of PCT/2008/003355, filed Apr. 25, 2008, which is based on and claims priority to U.S. Provisional Application Ser. No. 60/914,897, filed Apr. 30, 2007, which are hereby incorporated by reference.
BACKGROUND
• The present disclosure generally relates to the collection of body fluid for analysis, i.e., the determination of an analyte concentration therein and, in particular, relates to instruments and systems for producing a small body fluid sample by piercing the skin of a subject (human or animal) using a disposable lancing element having a skin piercing tip suitable for generating a small wound from which the sample is drawn. Depending on the skin site used and on the lancing depth the body fluid is blood or interstitial fluid or a mixture thereof.
• Analysis based on skin-piercing can be important in several fields of medical diagnostics and treatment. Of particular importance is the field of diabetes management. It has been determined that severe long term damages caused by diabetes mellitus can be avoided if the patient controls her or his blood sugar level several times a day in order to adapt the required insulin injections closely to the actual need for maintaining a constant blood sugar level. This requires so called “home-monitoring” by the patient himself or by other people not having a medical training.
• Other important fields of medical diagnostics and treatment with similar requirements, including home-monitoring, refer, for example, to the regular control of blood cholesterol and to the control of blood coagulation parameters. The present disclosure may be particularly suitable, but not limited, to home-monitoring applications. Similar requirements may also exist, e.g., in so-called “near-patient-testing.”
• Lancing of the skin is generally performed by a lancing system comprising, as mutually adapted components of the system, a reusable hand-held instrument and lancing elements. The movement for lancing (i.e., puncturing movement) is driven by a lancing drive provided inside a housing of the instrument and adapted for driving a lancing element connected thereto. Lancets can be interchangeably connected to the drive and generally are disposable items.
• After triggering the puncturing movement, the lancet is driven in a puncture direction until it reaches a point of maximum displacement and thereafter it is further driven in a reverse direction. Many suitable lancet drive mechanisms have been described in the prior art. In most cases, the driving force is supplied by a tensioned spring and the lancet drive further includes suitable mechanical means for converting the force of the spring into the required movement of a lancet.
• An important consideration in developing lancing systems can be the pain caused by the pricking action. This pain and the convenience of use are typically decisive factors determining compliance of the patient, i.e., his or her willingness to perform regular analyses as required for maintaining his or her health. The reliable production of the required amount of body fluid sample with minimum pain highly depends on the reproducibility of an optimum penetration depth of the tip of the lancing element into the skin (see e.g., U.S. Pat. No. 5,318,584).
• With earlier lancet systems, the analysis generally required a plurality of steps to be performed by the user. After lancing with such earlier systems, the body fluid sample typically did not readily emanate from the wound site in the lanced skin. Therefore, manual “milking” steps such as pinching, squeezing and kneading where necessary in order to express the required amount of body fluid sample. Finally, the body fluid sample was contacted to an analysis element of an analysis system, which typically was separate and distinct from the lancing system, and the analysis was performed thereby.
• In order to improve the production of the body fluid sample at the lancing site and to avoid the manual “milking,” several proposals have been made all of which relate to the design of the contact area at a distal end of the lancing instrument having a generally ring-shaped skin contact surface surrounding a skin contact opening. Such lancing systems have been described in: WO 99/26539; WO 01/89383 A2; EP 1 245 187 A1; EP 1 586 269; and EP 1 586 270.
• While these approaches differ in several ways, a common feature is that the skin contact opening has a relatively large diameter whereby the skin bulges into the skin contact opening forming a target site bulge which penetrates to some extent into the opening when the lancing instrument is pressed with its distal end, i.e., with the skin contact surface, against the skin. This bulging action, hereafter designated “target site bulging,” is generally combined with additional methods for improving body fluid sample production, such as, for example, a mechanical squeezing acting radially inwardly, a pumping action involving axial movement of parts of the instrument, etc.
• Ideally, these measures allow with a high success rate, preferably greater than 90%, expression of a sufficient amount of body fluid sample without manual “milking.” This again may be a requirement of integrated lancing and analysis systems which, in a single instrument, typically comprises both a lancing-type sample production and a method of analysis. Such integrated systems have been proposed in a plurality of variants which can be assigned generally to two types, namely:
• • A) “Two unit systems” comprising two separate units for lancing and for analysis in a single instrument housing. Typically, the units are moved one after the other to a common skin contact opening (see e.g., EP 1 669 028 A1 and EP 1 736 100 A1); or
  • B) “Single unit systems” comprising a single combined lancing and analysis unit suitable for performing both functions: lancing and analysis. Most of such systems operate with both integrated lancing and analysis elements. The two components of such combined lancing and analysis elements are generally manufactured separately but assembled by the manufacturer, or at least before use, i.e., before the lancing movement is triggered. In the instrument, such elements are typically processed as a unified item. In other single unit systems, both functions, lancing and analysis, are performed by the same unit but a lancing element and an analysis element are provided and processed separately during at least part of the analytical procedure. Examples of single unit systems are described generally in: WO 01/72220; WO 03/009759 A1; EP 1 342 448 A1; EP 1 360 933 A1; and EP 1 362 551 A1.
• Typically, target site bulging occurs when a lancing instrument is pressed against the skin, or vice versa, at the lancing site. While this bulging is favorable regarding expression of a sufficient amount of body fluid sample, it may cause a problem regarding reproducibility of the penetration depth by which the tip of the lancing element penetrates into the skin. With a given adjustment of the longitudinal position, i.e., position in the direction of the lancing movement; hereafter “z-position,” of the lancing drive and consequently a given z-position of the point of maximum displacement of the lancet the penetration depth depends on the exact z-position of the skin surface during the puncturing movement. Due to the bulging of this skin, position is substantially undefined. It depends on a plurality of factors including, not only differing skin elasticity of different users, but also including changes of the elastic and other properties of the skin of a particular user caused by influencing factors such as, for example, temperature, previous skin treatment, e.g., washing with soap, and choice of the particular lancing site.
• Prior art approaches for overcoming this uncertainty about the skin position and the resulting uncertainty about the penetration depth include:
• • (1) Detection of the exact z-position of the skin by a skin position detection device integrated into the lancing instrument and operating, for example, by electric (capacitive) or optical detection means (WO 03/088835), and
  • (2) Providing in the instrument, a penetration depth reference element having a reference skin contact surface which is contacted to the skin (additionally to the skin contact surface surrounding the skin contact opening of the instrument), for providing a reliable z-position reference during penetration of the lancing element tip into the skin. Such a reference element can be moved towards the skin separately from the lancing element (see e.g., EP 1 669 028 A1) or together therewith (see e.g., WO 2006/092309).
• While these approaches may help to achieve a reproducible penetration depth, they still require a substantial expense in the instrument design and production, making the system less handy and more costly. Therefore, several of the lancing systems designed for target site bulging simply disregard the penetration depth uncertainty. This approach causes, however, a much more pain than necessary, because it requires a higher penetration depth setting to make sure that a sufficient amount of body fluid sample is produced even with a disadvantageous position of the lancing site bulge.
• According to the prior art, timing has generally been only a concern with respect to the “test time”, i.e., the total time required for the analysis from lancing until the analyte concentration is indicated. In contrast, according to the present disclosure, the duration of the minimum interaction time period (“MITP”) can be highly critical. This time period can be defined as the minimum time duration for which user-instrument interaction can be required for lancing and for collecting a sufficient amount of sample for the analysis in a sample collection device of the system. The functions performed during the MITP can include lancing, expression of body fluid sample from the tissue, preferably directly into a capillary of the lancing element, and collecting a sufficient amount of sample.
• The MITP can be a system-related quantity which can be user-independent, i.e., only determined by the design of the instrument, and possibly by other components of the system. It may not be confused with the actual time of interaction which in each case can depend on numerous aspects including the habits of the user. The actual interaction time generally can vary between users and, even for a specific user, from analysis to analysis. The present disclosure can design the system in such a manner, that the minimum time for which every user must at least interact with the instrument, can be below the indicated very small threshold values.
• Even though several of the discussed systems, in particular integrated lancing and analysis systems, provide improved results as compared to earlier known devices, they still posses substantial shortcomings. Therefore, there is a need for improvements to lancing and analysis systems that may include, for example, ease of use and minimum pain as well as minimum volume, weight and production costs.
• Furthermore, many users of integrated lancing and analysis systems have problems maintaining a sufficient pressing force for a sufficient period of time. Therefore, there is a need for a system that improves user compliance with recommended rules.
SUMMARY
• According to the present disclosure, an instrument and a system for producing a sample of body fluid by piercing the skin is disclosed. The instrument and system can comprise a housing, a lancing drive within the housing adapted for being connected to a lancing element and adapted for driving a lancing element connected thereto in a puncturing movement in which the lancing element moves, after triggering the puncturing movement, in a puncture direction until it reaches a point of maximum displacement and in a reverse direction after it has reached the point of maximum displacement, and a pressure ring surrounding a skin contact opening and being adapted for being pressed against the skin such that the skin bulges into the opening whereby expression of body fluid is promoted after the piercing tip of a lancing element has pierced the skin. The skin contact opening can have an opening area corresponding to a circle with a diameter of at least about 3 mm and at most about 8 mm. The instrument can include a pressing force control device for controlling the force acting between the pressure ring and the skin (“pressing force”) at the time of triggering the puncturing movement, to be at least about 3 N and at most about 8 N.
• In accordance with one embodiment of the present disclosure, the system and an instrument for producing a sample of body fluid by piercing the skin can use a lancing element having a skin piercing tip and, for analysis, can use a disposable analysis element. The instrument can comprise a housing, a lancing drive within the housing adapted for being connected to a lancing element and adapted for driving a lancing element connected thereto in a puncturing movement in which the lancing element moves, after triggering the puncturing movement, in a puncture direction until it reaches a point of maximum displacement and in a reverse direction after it has reached the point of maximum displacement, a pressure ring surrounding a skin contact opening and being adapted for being pressed against the skin such that the skin bulges into the opening whereby expression of body fluid is promoted after the piercing tip of a lancing element has pierced the skin, and a holding device adapted for holding an analysis element in the housing such that a sample of body fluid produced by piercing the skin can be transported thereto for analysis. A minimum interaction time period required for lancing and sampling a sufficient amount of body fluid sample for analysis can be at most about 3 seconds. Preferably the minimum interaction time period can be no more than about 2 seconds and more preferably it can be no more than about 1 second.
• In accordance with another embodiment of the present disclosure, the user can interact with the system by establishing a pressing force between the skin and the pressure ring of the instrument by pressing the hand-held instrument against the finger or other body part. Alternatively, the finger or other body part can be pressed against the instrument by, for example, lying on a table.
• Accordingly, it is a feature of the embodiments of the present disclosure to provide lancing and analysis systems with improvements such as, for example, ease of use, minimum pain, user compliance, and minimum volume, weight and production costs. Other features of the embodiments of the present disclosure will be apparent in light of the description of the disclosure embodied herein.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
• The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
• FIG. 1 illustrates a schematic sketch relating to the principles of target site bulging according to an embodiment of the present disclosure.
• FIG. 2 illustrates a perspective view of an analysis instrument according to an embodiment of the present disclosure.
• FIG. 3 illustrates a longitudinal section of the instrument shown inFIG. 2 according to an embodiment of the present disclosure.
• FIG. 4 illustrates a perspective view of a lancing element for use in the instrument shown inFIG. 3 according to an embodiment of the present disclosure.
• FIG. 5 illustrates a schematic sketch regarding an aspect of the function of the instrument shown inFIG. 3 according to an embodiment of the present disclosure.
DETAILED DESCRIPTION
• In the following detailed description of the embodiments, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration, and not by way of limitation, specific embodiments in which the disclosure may be practiced. It is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the spirit and scope of the present disclosure.
• Referring initially toFIGS. 1-3,FIG. 1 illustrates symbolically the point P of maximum displacement which a piercingtip7 reaches on its movement path during the puncturing movement. In one embodiment, a “two unit system,” thesample collection device36 can belong to the analysis unit. It can be a part of ananalysis element21, or of a dedicated sample collection element, and can collect body fluid sample after the analysis unit has been moved to the skin contact opening4. In another embodiment, a “single unit system,” thesample collection device36 can be a part of a lance element, a part of ananalysis element21, a part of an integrated lancing andanalysis element22 or a part of a dedicated sample collection element.
• If thesample collection device36 is a part of ananalysis element21, or of an integrated lancing andanalysis element22, it can, in particular, be a part of a reaction zone thereof containing reagents which react with the body fluid sample, thereby producing some kind of measurable physical change which can be characteristic for the analysis.
• In one exemplary embodiment, thesample collection device36 can be separate from the reaction zone of theanalysis element21 and can include a reservoir, which can be suitable for storing a body fluid sample for an intermediate storage time which may be longer than the minimum interaction time period (“MITP”). One advantage of this embodiment can be that it can allow to separate the timing requirements of the sample collection from the timing requirements of the analysis. The MITP can be terminated as soon as the reservoir of thesample collection device36 contains a sufficient amount of body fluid sample for the analysis. Further steps, including, for example, the filling of a reaction zone, can take place separately without continued interaction of the user. The transfer of the body fluid sample from the reservoir of thesample collection device36 to the reaction zone of theanalysis element21 can either take place spontaneously or with controlled timing. In the former case, permanent fluid communication can be provided between the reservoir and the reaction zone. In the latter case, the fluid communication from the reservoir of thesample collection device36 to theanalysis element21 can be “switchable,” i.e., initially, preferably at least for the duration of the MITP, there may be no fluid communication but same may be established in a controlled manner at a suitable point of time. Suitable methods for such switching are well known in the art.
• Returning toFIG. 1, a pressure ring1 against which a finger tip2, or any other suitable body part, can be pressed with a pressing force F. Due to this pressing force F, the skin3 may bulge into a skin contact opening4 which can be defined by the pressure ring1, forming a target site bulge6. Withmost lancing instruments11, the z-positions of the plane of the pressure ring1 and the point of maximum displacement P relative to each other, shown as distance sFIG. 1, can be adjusted in order to allow a penetration depth setting.FIG. 1 illustrates, that for a given value of this adjustment, the actual penetration depth x can depend directly on the distance d, i.e., the degree of target site bulging6.
• The degree of target site bulging6, i.e., the distance d between the plane of pressure ring1 and the apex of target site bulge6, can be influenced by many factors such as, for example, the size of the skin contact opening4, the pressing force F and the viscoelastic properties of the skin3. These factors can further depend on a plurality of other aspects including, for example: (1) the elasticity of the skin3 surface of the particular individual which largely differs depending on age, sex and degree of manual work generally performed by the particular person; (2) the internal pressure in the finger2, or other body part, which depends among others on the health status and the physical activity of the particular person; (3) ambient conditions, including in particular temperature and humidity, influencing the viscoelastic properties of the skin3; and (4) skin3 treatment preceding the lancing, such as washing with soap, disinfecting etc.
• Generally, the skin contact opening4 can be substantially circular. In one embodiment, the skin contact opening4 can have an inner, free diameter in the range of at least about 3 mm to about 8 mm. In another embodiment, the skin contact opening4 can have an inner, free diameter in the range of at least about 4 mm to about 7 mm. In yet another embodiment, the skin contact opening4 can have an inner, free diameter in the range of at least about 5 mm to about 6.5 mm. In still another embodiment, the skin contact opening4 can have an inner, free diameter in the range of at least about 5.5 mm to about 6 mm. In the case of a non-circular skin contact opening4, the area of the skin contact opening4 can substantially correspond, i.e., be about the same, as the area of a circle with the above mentioned diameter values. However, in one embodiment, the smallest inner, free width of a non-circular skin contact opening4 can be at least about 3 mm. In another embodiment, the smallest inner, free width of a non-circular skin contact opening4 can be at least about 4 mm.
• As noted above, in the prior art, the uncertainty about the actual z-position of the skin3, i.e., the apex of the target site bulge6, has either been disregarded or has been taken into account by measuring or referencing the actual skin3 position. In contrast, the present disclosure has surprisingly found that a very good reproducibility of the penetration depth during lancing can be achieved if the specified conditions concerning the area of the skin contact opening4 and the amount of the pressing force F are maintained.
• FIGS. 2-5 illustrate anexemplary lancing system10. The lancingsystem10 can include a reusable hand-heldinstrument11 and a disposable lancingelement12 with a piercingtip7. Ahousing13 of theinstrument11 can contain a lancingdrive14 and a measurement andevaluation electronics15, shown symbolically inFIG. 3. Adisplay16 can be provided to the user in order to allow visual indication of information including, for example, status information concerning the lancingsystem10, advice concerning its handling, analytical results and any other suitable information. Optionally, theinstrument11 also can comprise a MITP controlling device17, adevice18 for generating audible signals such as, for example, a buzzer, and/or adevice19 for generating tactile signals such as, for example, a vibration generator.
• In one exemplary embodiment, best shown inFIG. 4, a lancingelement12 can be combined with ananalysis element21 to form an integral lancing andanalysis element22. In theintegral element22, the lancingelement12 can be movable in a longitudinal direction symbolized by thedouble arrow34. Ananalysis element holder20 can be provided for holding theanalysis element21 inside theinstrument11. In one exemplary embodiment, theanalysis element holder20 can comprise acoupling recess25 in theanalysis element21 and acorresponding coupling protrusion27 of theinstrument11. In a similar manner, the lancingelement12 can have acoupling recess24 cooperating with acoupling protrusion26 of theinstrument11. These pairs ofrecesses24,25 andprotrusions26,27 can penetrate into the respective coupling recesses24,25 to allow for the handling of an integral lancing andanalysis element22 which can be inserted into theinstrument11, as seen inFIG. 3.
• In one embodiment, thelancet drive14, shown inFIG. 3, can comprises adrive rotor29 with acam30 formed by a groove. Thecam30 and acorresponding cam traveler31 can form a cam drive mechanism which can control a pivoting movement of adrive rod32 about a pivotingaxis33.
• After triggering of a puncture movement, by a triggering method, thedrive rotor29 can turn with high speed, driven by a drive spring, about itsaxis35. This rotational movement can be translated by a cam curve formed bygroove30 and traveled bycam traveler31 into a corresponding pivoting movement ofdrive rod32 which again can drive a corresponding up and down movement of lancingelement12 to which it can be connected by itscoupling protrusion26 penetrating intocoupling recess24.Similar drive rotor29 for lancinginstruments11 are known in the art, therefore, no more detailed description may be necessary.
• In the exemplary embodiment shown inFIG. 4, the lancingelement12 can be a “direct sampler” having acapillary channel28 inside its piercingtip7 and leading up to asample collection zone23 of lancingelement12. Insample collection zone23, thecapillary channel28 can widen to form asample reservoir chamber28a.
• During lancing, the lancingelement12 can perform a puncturing movement by which piercingtip7 can be driven into skin3. Thereafter, during a retraction phase of the puncturing movement, after the piercingtip7 has reached its point of maximum displacement P but with the piercingtip7 still below the surface of skin3, a body fluid sample can penetrate, driven by capillary forces, into thecapillary channel28 andreservoir chamber28a. Thus, the capillary28 andreservoir chamber28atogether can form asample collection device36 suitable for storing body fluid sample, ready for subsequent transfer to an analysis zone8 ofanalysis element21.
• Once the body fluid sample arrives atsample collection zone23, it may be transferred to the adjacent analysis zone8 ofanalysis element21 by a suitable fluid communication device. In one embodiment, the arrangement can be such that there can beno fluid communication between thesample collection zone23 of lancingelement12 and theanalysis element21. In a second embodiment, fluid communication can take place. The switching between the two embodiments can be accomplished by any suitable method known in the art such as, for example, by pressingsample collection zone23 of lancingelement12 andanalysis element21 together.
• Alternatively, the present disclosure can also be used with integral lancing andanalysis elements22 having a lancing part and an analysis part fixed together. In this embodiment, two separate holding devices may not be required. Instead, one holding device may be provided which simultaneously serves as lancingelement12 holding device and as analysis element holding device.
• While devices for holding and moving a lancingelement12 and ananalysis element21, or an integral lancing andanalysis element22, in theinstrument11 have been described, many other suitable devices can be possible. Such devices can include, for example, a design in whichanalysis elements21 and/or lancingelements12 can be fixed to and transported by means of a tape during at least a part of the lancingsystem10 operation.
• In one embodiment, the pressing force F acting at the time of triggering the puncturing movement between the pressure ring1 and the skin3 can be in the range of at least be about 3 N to about 8 N. In another embodiment, the pressing force F acting at the time of triggering the puncturing movement between the pressure ring1 and the skin3 can be in the range of at least be about 4 N to about 7 N. In yet another embodiment, the pressing force F acting at the time of triggering the puncturing movement between the pressure ring1 and the skin3 can be in the range of at least be about 5 N to about 6 N. A defined pressing force F within these limits can be ensured by a suitable pressingforce control device37. The limiting values of the pressure force can be with respect to the requirements of withdrawing sample from the skin3.
• However, this does not mean that the pressing force F can be allowed to float in that range during the MITP. Rather, in one exemplary embodiment, the maximum variation range of the pressing force F can be limited to no more than about 15%. In another exemplary embodiment, the maximum variation range of the pressing force F can be limited to no more than about 10%. In yet another exemplary embodiment, the maximum variation range of the pressing force F can be limited to no more than about 5%. Expressed in absolute values, in one exemplary embodiment, the maximum variation range of the pressing force F between the pressure ring1 and the skin3 during the MITP may be no more than about +/−0.5 N. In another exemplary embodiment, the maximum variation range of the pressing force F between the pressure ring1 and the skin3 during the MITP may be no more than about +/−0.3 N and, in yet another exemplary embodiment, the maximum variation range of the pressing force F between the pressure ring1 and the skin3 during the MITP may be no more than about +/−0.2 N.
• In one exemplary embodiment, the pressingforce control device37 can be mechanical, in particular, it can comprise aspring device38 which can be arranged in such a manner that its spring force can act between the pressure ring1 and thehousing13. In one embodiment, thespring device38 can be a metal spring. Other suitable spring-like devices are, however, known in the art and can be used, such as, for example, a pneumatic spring or a resilient element of an elastic material. Hereafter, the term “spring” can be used as an example of anysuch spring device38. In one exemplary embodiment, thespring device38 can be pre-tensioned.
• In one exemplary embodiment, pressingforce control devices37 operating by electrical methods may comprise an electromagnetic drive including a coil and a magnetic core, in particular a voice coil drive. The control of the pressure can be fully automatic or it can require an activity of the user. In the latter case, electrical methods can be used to measure the force by which the pressure ring1 may be pressed against the skin3 and this force can be indicated to the user by suitable visible, acoustic or tactile methods, whereby the user can adapt the pressing force F to the desired value.
• A special feature according to one embodiment of the present disclosure can relate to a pressingforce control device37 provided in theinstrument11. In this embodiment, the pressingforce control device37 can comprise aspring38 which can be embodied and arranged in such a manner that one end thereof can act against pressure ring1 and the other end can act against thehousing13. The term “acting” in this context may not require immediate contact. Instead, it can mean that the spring can exert a force on the pressure ring1 and that the corresponding counter-force can be, directly or indirectly, borne by thehousing13.
• In one embodiment, theinstrument11, shown inFIG. 3, can comprise one end ofspring38 that can rest on a wall ofhousing13 and another end that can press against aframe element39 carrying lancingdrive14. The force ofspring38 can be further transmitted from theframe element39 to pressure ring1 viapillar elements40. Pressure ring1 can be embodied as part of apressure piece42 which can be borne by a pressure ring bearing43 ofhousing13 such that it can be axially movable against the force ofspring38.
• In one exemplary embodiment, when a user presses her or his finger tip2 in the direction of arrow F ontopressure piece42 with pressure ring1, the latter can move downwardly against the force ofspring38, orother spring device38 known in the art. As soon as the contact betweenpressure piece42 and thehousing13 at pressure ring bearing43 is interrupted, the force ofspring38 can be balanced by the pressing-down force of the finger2. In other words, the force by which the pressure ring1 may be pressed against the skin3 can be in this status controlled by the pressingforce control device37, such as, for example, by aspring38.
• FIG. 5 illustrates that thespring38 can act betweenhousing13 andpressure piece42 with pressure ring1. The lancingdrive14 can be connected in a defined spatial configuration with pressure ring1, in such a manner that the distance between the point of maximum displacement P of the lancet movement and the pressure ring1 can be independent from the compression status of thespring38 and the corresponding axial movement ofpressure piece42. In one exemplary embodiment, the spatial configuration and, hence, the distance of the pressure ring1 from the point of maximum displacement P can be varied, between puncturing movements, to set the lancing penetration depth. However, it can be fixed during the interaction of the user with the device, i.e., from the point of time at which the pressure ring1 can be first pressed down until the body part2 is removed therefrom.
• Theelastic spring38 can increase linearly with its elongation, i.e., compression in the case of a compression spring as shown. In one exemplary embodiment, the pressure ring1 pressed against the skin3 can be controlled closely, i.e., the variation thereof may not exceed the preferred limiting values. In this exemplary embodiment, thespring38 can be arranged in such a manner that it may be pre-tensioned. This means that the spring can already be compressed, or in the case of an extension spring can be extended, even if no pressing force F is exerted onto pressure ring1, i.e., the pressure ring1 is in its “home” position resting on the surrounding wall, bearing43, ofhousing13. In one exemplary embodiment, the degree of this pre-tensioning can be such that the force ofspring38 acting on the pressure ring1 can vary by no more than about 20% within the spring-loaded movement range of the pressure ring1. In another exemplary embodiment, the force ofspring38 acting on the pressure ring1 can vary by no more than about 10%.
• In this context, it may be important to make sure, that in the entire movement range, the pressing-force acting between the finger2, or other body part, and the pressure ring1 can be controlled only by the force ofspring38 balanced by the pressing-down-force of finger2. This condition may not be met if the movement of pressure ring1 was influenced or limited by some kind of abutting member or obstacle acting, within its possible movement range, on ring1. In order to meet this condition, a pressure ring movement limiting arrangement44 (seeFIG. 5) can be provided by which the maximum displacement P of the pressure ring1 possible by pressing with a finger2, or other body part, can be limited within a fully spring-loaded movement range of the pressure ring1.
• In one exemplary embodiment, shown inFIG. 5, this can be achieved by acontact surface46 which can be arranged in the vicinity, at the outer side, of the pressure ring1 in such a manner that a body part pressed against the pressure ring1, and thereby moving the pressure ring1, can abut against thecontact surface46. Due to this abutting, the pressure ring1 cannot be moved further, i.e., the possible displacement of the pressure ring1, by the body part2 pressing thereagainst, can be limited. In this embodiment, the maximum displacement P can depend on the distance dr by which the pressure ring1 can protrude from theinstrument housing13,contact surface46. Whenpressure piece42 with pressure ring1 is pressed downwardly, this movement can be discontinued when finger tip2 contacts the surface ofhousing13 in the vicinity of the pressure ring1.
• It may be favorable for the maximum displacement P of the pressure ring1 during practical use to be small. In one embodiment, it can be less than about 3 mm. In another embodiment, it can be less than about 2 mm. In still another embodiment, it can be less than about 1 mm. Therefore, the distance dr of the plane of pressure ring1 and theadjacent housing13 surface, may not be too large. In one exemplary embodiment, maximum values can be calculated by adding approximately 0.5 mm to the mentioned maximum displacement P values.
• On the other hand, dr may not be too small because a protrusion of the pressure ring1 versus theadjacent housing13 area can simplify the finding of a suitable finger2 position for the user. Therefore, in one embodiment, this protrusion, i.e., the distance, dr, can be at least about 0.2 mm. In another embodiment, the distance, dr, can be at least about 0.5 mm.
• In one exemplary embodiment, the pressure ring1 may be non-deformable in the sense that it may not be visibly deformed during normal use of the lancingsystem10. A suitable exact shape and width of the pressure ring1 can be determined experimentally. In one embodiment, the pressure ring1 can have a width of at most about 3.5 mm. In another embodiment, the pressure ring1 can have a width of at most about 2.5 mm. In yet another embodiment, the pressure ring1 can have a width of at most about 1 mm. In one embodiment, the pressure ring1 can have a minimum width of about 0.5 mm. In another embodiment, the pressure ring1 can have a minimum width of about 0.7 mm. In yet another embodiment, the pressure ring1 can have a minimum width of about 0.8 mm. The pressure ring1 may protrude from anyadjacent housing13 surface by a sufficient distance to allow easy tactile recognition thereof by the user.
• Of course, the pressure ring1 can have many different shapes and designs as known in the art. The term “pressure ring” can refer to the ring-shaped surface of the respective part which in practical use, i.e. under the conditions prevailing in using of theparticular instrument11, can contact the skin3 surface. Of course, this ring-shaped contact surface (i.e., the pressure ring1) can have varying shapes including, for example, slightly rounded edges.
• Furthermore, the term “pressure ring” may not be being limited to an uninterrupted ring. Instead, the ring shaped surface contacting the skin3 can have interruptions such as, for example, recesses, which may, however, be small enough not to spoil the described function of the pressure ring1.
• Excellent reproducibility of the z-position of the skin bulge6 at the lancing site and, thus, an excellent reproducibility of the penetration depth can be achieved if particular conditions are ensured concerning the size of the skin contact opening4 and concerning the force by which the pressure ring1 and the skin3 can be pressed against each other at the time of triggering the puncturing movement. This can allow target site bulging and automatic sample generation, without “milking,” combined with a simple and inexpensive design of the lancingsystem10. The lancingsystem10 can work without a z-position detection and without a penetration depth reference element adapted for contacting the skin3 which can bulge into the pressure ring1.
• The starting point of the MITP can be a point in time at which the lancingsystem10 may be “ready for lancing”, i.e., the lancingdrive14 may be ready for driving a lancing movement of a lancingelement12 connected thereto and the desired lancing site of the skin3 may be properly located at the skin contact opening4 of theinstrument11. Depending on the design of the lancingsystem10, a short period of time may be required between establishing the status “ready for lancing” and the triggering of the puncturing movement. Such a short preparatory delay period may be required by theinstrument11, for example for detecting the skin3 position. However, in one embodiment, no such preparatory time period may be needed due to instrumental requirements, i.e. the triggering can immediately take place when the status of the lancingsystem10 is “ready for lancing.” In this embodiment, the starting point of the MITP may coincide with the triggering of the puncturing movement.
• However, a very short, well defined preparatory delay period may, however, be provided for non-instrumental reasons; in particular, to take into account visco-elastic deformation of the skin3 which may take place after establishing a pressure force between the skin3 and the pressure ring1.
• The end of the MITP may be marked by the fact that a sufficient amount of body fluid has been sampled, i.e., may be available in thesample collection device36 of theinstrument11 for analysis. A “sample collection device”36 as used herein can be any part of the lancingsystem10, inside theinstrument11, in which body fluid sample produced as a result of skin lancing can be available for analysis. It can, for example, be a chamber or capillary and can be empty, or filled with bibulous material.
• In one embodiment, the MITP can be a user-independent quantity which may depend only on the design of the lancingsystem10. However, in another embodiment, theinstrument11 can comprise a MITP controlling device17. This term can refer to any device which can help ensure that the required interaction between the user and theinstrument11, i.e., the required pressing force F between the skin3 and the pressure ring1, is maintained by the user at least during the MITP. In other words, the MITP controlling device17 can provide assistance to ensure that the actual interaction between the user and theinstrument11 overlaps, or at least coincides with, the MITP.
• The MITP controlling device17 need not operate fully automatically in the sense that no acts of the user, such as manual triggering of the puncturing movement, may be required. Rather, it may provide assistance to the user, in particular, by signaling to the user directly or indirectly the start and the end of the MITP. In one embodiment, the end of the MITP period can generally be indicated to the user by a suitable visible, audible or tactile signal.
• The MITP controlling device17 can comprise detecting the starting point of the MITP, by detecting the pressing force F acting between a pressure ring1 and the skin3 using any suitable methods known in the art. In one embodiment, when the pressure corresponds to a predetermined minimum value or range, this status can be indicated to the user by a suitable visible, audible or tactile signal. Alternatively, the lancing movement can be triggered automatically when the status “ready for lancing” has been detected. In this case, there may be no delay between “ready to lance” and triggering, i.e., the MITP starts with the automatic triggering. Alternatively, there may be an instrument-controlled delay time, e.g., to take into account the time needed for visco-elastic skin-deformation. In one embodiment, the preparatory delay period between “ready to lance” and triggering can range between about 0.2 sec to at most about 1 sec. In another embodiment, the preparatory delay period can range between about 0.3 sec to at most about 0.7 sec. In yet another embodiment, the preparatory delay period can range between about 0.4 sec to at most about 0.5 sec.
• However, a dedicated MITP controlling device17 may not be necessary. Depending on the particular situation, it may be sufficient for the user to be provided with an indirect indication of the start and end of the MITP. For example, the “ready to lance” status can be “felt” by the user when pressing his finger2 on a spring-supported pressure ring1 and the duration of the MITP may be so short, that it may by sufficient to rely on the “feeling” of the user with respect to the end of the MITP.
• In one embodiment, theinstrument11 may have a fill control, as part of the MITP controlling device17, to indicate a sufficient amount of body fluid sample or to allow an analysis, only if a sufficient amount of sample has been collected. However, the fill control may not be required. Rather, the end of the MITP can be calculated by theinstrument11 using a fixed MITP value (depending on the design of the lancingsystem10 components).
• Advantages can be achieved with integrated lancing andanalysis systems10 if the pressing force F between the pressure ring1 at the distal end of the lancinginstrument11 and the skin3 is maintained, not only at the time of lancing, but, also, for a short interaction period thereafter: (1) With both types of integrated lancing andanalysis systems10, maintaining this pressing force F for a MITP can help to produce a sufficiently large volume of body fluid sample; (2) In the case of two unit system, maintaining a MITP with the described pressing force F can furthermore be important to make sure that the position of theinstrument11, i.e., its skin contact opening4, relative to the skin3 can be fixed until the point of time that the analysis device can be moved to the skin contact opening4; and (3) With single unit system, maintaining a MITP with the described pressing force F can be important in order to allow a precise z-position of the lancing tip, thereby improving suctioning of a sufficient amount of body fluid sample during a short period of time.
• In one exemplary embodiment, shown inFIG. 3, theinstrument11 furthermore can comprise a pressure-ring-movement detection device45. In one embodiment, the pressure-ring-movement detection device45 can be part of a MITP controlling device17. Movement detection can be, for example, a light barrier. Such a device can detect the movement of apressure piece42, and, hence, of the pressure ring1, upon pressing down from its “home” position by a finger2. Such detection can allow several favorable functions including an indication to the user, viadisplay16 or generators of audible ortactile signals18 and19, that theinstrument11 is “ready for lancing.” Alternatively, or additionally, the signal of the pressure-ring-movement detection device45 can be used for automatically triggering the lancing movement, possibly after a delay time as described above.
• FIG. 3 furthermore shows an analysis measurement device47 as part of theinstrument11. This can be any device suitable to measure a value of a measurement quantity relating to a change ofanalysis element21, wherein change can be a measure of the desired analytical value. In one embodiment, the analysis measurement device47 can be for a photometric measurement of a detection area in the analysis zone8 ofanalysis element21 including alight source48, alight detector49 and corresponding light guide means symbolized by alens50. Other types of analysis measurement devices47 can be used as well, such as, for example, electrical measurement devices for the evaluation ofelectrochemical analysis elements21.
• In the lancingsystem10 illustrated inFIGS. 2 to 5, a MITP control device17 can make use of the pressure-ring-movement detection device45. Once MITP control device17 signals the start of an MITP, it can generate a signal by at least one ofsignal generator devices18 and19 and/or can automatically trigger a puncturing movement oflancet drive14. The end of the MITP period can be determined by the measurement andevaluation electronics15, for example, on the basis of a predefined time period required for generation and transfer of sufficient amount of body fluid sample from the finger tip2. Alternatively, the status of a sufficient sample transfer may be separately detected by suitable sample transfer detection as is known in the art, such as, for example, photometric detection of the sample transported in the integral lancing andanalysis element22, or by electrical contacts detecting that body fluid sample transported therein has reached a certain point in its transport path. The application force control device can ensure that during the entire MITP, the pressing force F is within a given range. The variation of the pressing force F during the MITP may be within the identified variation limitations which can be much smaller.
• It has been found, that with suitable adaption of the minimum pressing force F and, also, of the upper limit of the pressing force F, and the maximum variation range, advantageously combined with a size of the skin contact opening4, it can be even possible to design aninstrument11 with no user-setable penetration depth adjustment. Surprisingly, with a single factory-set z-position of thelancet drive14, point of maximal displacement, and of the pressure ring1, relative to each other, a reliable production of body fluid sample can be possible with very little pain. Simultaneously, omission of a penetration depth adjustment device can allow a simple, compact and inexpensive design of theinstrument11.
• Even if a user-setable penetration depth adjustment device is provided, the present disclosure can use a simple and inexpensive design. For example, in order to adapt for small remaining variations of the skin3 position, it may be sufficient to provide interchangeable distance elements or pressure rings1 to allow a single adaption of the lancingsystems10 to the needs of a particular user.
• In general, theinstrument11 and lancingsystem10 can take into account the viscoelastic properties of the skin3 in an optimized manner. In this way, not only a sufficient supply of body fluid sample can be ensured but also “flooding” by too much body fluid sample can be avoided. Reliable analysis can be possible even with very small sample volumes, e.g., less than about 300 nl, or even less than about 200 nl.
• It is noted that terms like “preferably,” “commonly,” and “typically” are not utilized herein to limit the scope of the claimed embodiments or to imply that certain features are critical, essential, or even important to the structure or function of the claimed embodiments. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure.
• For the purposes of describing and defining the present disclosure, it is noted that the term “substantially” is utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term “substantially” is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.
• Having described the present disclosure in detail and by reference to specific embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the disclosure defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these preferred aspects of the disclosure.

Claims (42)

1. An instrument for producing a body fluid sample for analysis by piercing skin with a lancing element having a piercing tip, the instrument comprising:

a housing;

a lancing drive within the housing for driving a lancing element connected thereto in a puncturing movement in which the lancing element moves, after triggering the puncturing movement, in a puncture direction until it reaches a point of maximum displacement and in a reverse direction after it has reached the point of maximum displacement;

a pressure ring surrounding a skin contact opening and adapted for pressing against the skin such that the skin bulges into the skin contact opening for promoting expression of body fluid, wherein the skin contact opening has a circular opening with a diameter of at least about 3 mm and at most about 8 mm; and

a pressing force control device for controlling a pressing force between the pressure ring and the skin at the time of triggering the puncturing movement, wherein the pressing force ranges between about 3 N and at the most about 8 N.

2. The instrument according toclaim 1, wherein the skin contact opening has a circular opening with a diameter of at least about 4 mm and at most about 7 mm.

3. The instrument according toclaim 1, wherein the skin contact opening has a circular opening with a diameter of at least about 5 mm and at most about 6.5 mm.

4. The instrument according toclaim 1, wherein the skin contact opening has a circular opening with a diameter of at least about 5.5 mm and at most about 6 mm.

5. The instrument according toclaim 1, wherein the pressing force ranges between at least about 4 N and at most about 7 N.

6. The instrument according toclaim 1, wherein the pressing force ranges between at least about 5 N and at most about 6 N.

7. The instrument according toclaim 1, further comprising,

a holding device for holding an analysis element in the housing such that the body fluid sample produced by piercing the skin can be transported thereto for analysis.

8. An instrument for producing a body fluid sample by piercing skin and for analyzing the body fluid sample comprising a lancing element having a piercing tip, a sample collection device for collecting an amount of body fluid sample required for analysis and a disposable analysis element, wherein the instrument further comprises:

a housing;

a lancing drive within the housing connected to a lancing element and for driving the lancing element connected thereto in a puncturing movement in which the lancing element moves, after triggering the puncturing movement, in a puncture direction until it reaches a point of maximum displacement and in a reverse direction after it has reached the point of maximum displacement;

a pressure ring surrounding a skin contact opening and adapted for being pressed against the skin such that the skin bulges into the skin contact opening for promoting expression of body fluid; and

a holding device for holding the disposable analysis element in the housing such that the body fluid sample is transported thereto from the sample collection device for analysis;

wherein a minimum interaction time period required for lancing and sampling a sufficient amount of body fluid sample for analysis is at most about 3 seconds.

9. The instrument according toclaim 8, wherein the minimum interaction time period is not more than about 2 seconds.

10. The instrument according toclaim 8, wherein the minimum interaction time period is not more than about 1 second.

11. The instrument according toclaim 8, further comprising,

a minimum interaction time controlling device for controlling the minimum interaction time maintained by a user of the instrument.

12. The instrument according toclaim 11, wherein the minimum interaction time controlling device comprises,

a signal generating device adapted to generate an audible, tactile or visible signal for the user at the beginning of the minimum interaction time period and at the end of the minimum interaction time period.

13. The instrument accordingclaim 8, further comprising,

a pressing force control device for controlling the pressing force between the pressure ring and the skin.

14. The instrument according toclaim 13, wherein the pressing force control device maintains a minimum pressing force of at least about 3 N between the pressure ring and the skin during the measurement interaction time period.

15. The instrument according toclaim 13, wherein the pressing force control device maintains a minimum pressing force of at least about 4 N between the pressure ring and the skin during the measurement interaction time period.

16. The instrument according toclaim 13, wherein the pressing force control device maintains a minimum pressing force of at least about 5 N between the pressure ring and the skin during the measurement interaction time period.

17. The instrument according toclaim 13, wherein the pressing force control device maintains a maximum pressing force of at most about 10 N between the pressure ring and the skin during the measurement interaction time period.

18. The instrument according toclaim 13, wherein the pressing force control device maintains a maximum pressing force of at most about 8 N between the pressure ring and the skin during the measurement interaction time period.

19. The instrument according toclaim 13, wherein the pressing force control device maintains a maximum pressing force of at most about 7 N between the pressure ring and the skin, during the measurement interaction time period.

20. The instrument according toclaim 13; wherein the pressing force control device maintains a maximum variation range of the pressing force between the pressure ring and the skin during the measurement interaction time period of not more than about +/−0.5 N.

21. The instrument according toclaim 13, wherein the pressing force control device maintains a maximum variation range of the pressing force between the pressure ring and the skin during the measurement interaction time period of not more than about +/−0.3 N.

22. The instrument according toclaim 13, wherein the pressing force control device maintains a maximum variation range of the pressing force between the pressure ring and the skin during the measurement interaction time period of not more than about +/−0.2 N.

23. The instrument accordingclaim 13, wherein the pressing force control device maintains a maximum variation range of the pressing force between the pressure ring and the skin during the measurement interaction time period of not more than about +/−15%.

24. The instrument accordingclaim 13, wherein the pressing force control device maintains a maximum variation range of the pressing force between the pressure ring and the skin during the measurement interaction time period of not more than about +/−10%.

25. The instrument accordingclaim 13, wherein the pressing force control device maintains a maximum variation range of the pressing force between the pressure ring and the skin during the measurement interaction time period of not more than about +/−5%.

26. The instrument according toclaim 13, wherein the pressing force control device comprises a spring device arranged such that one end of the spring device acts against the pressure ring and the other end of the spring device acts against the housing.

27. The instrument according toclaim 26, wherein the lancet drive is connected with the pressure ring in a defined spatial configuration, such that the distance between the point of maximum displacement of the lancet movement and the pressure ring is independent from the compression status of the spring device and from the axial movement position of the pressure ring.

28. The instrument according to any one ofclaims 26, further comprising,

a pressure ring movement limiting arrangement, by which the maximum displacement of the pressure ring possible by pressing with a finger or other body part is limited within a spring-loaded movement range of the pressure ring.

29. The instrument according toclaim 28, wherein the pressure ring movement limiting arrangement comprises a contact surface in the vicinity of the pressure ring arranged such that a body part pressed against the pressure ring and thereby moving the pressure ring, abuts against the contact surface.

30. The instrument according toclaim 26, wherein the spring device is pre-tensioned such that its force acting on the pressure ring varies by not more than about 20% within the spring-loaded movement range of the pressure ring.

31. The instrument according toclaim 26, wherein the spring device is pre-tensioned such that its force acting on the pressure ring varies by not more than about 10%, within the spring-loaded movement range of the pressure ring.

32. The instrument according toclaim 8 has no user-setable penetration depth adjustment.

33. The instrument according toclaim 8, further comprising, a device for automatically triggering of the puncturing movement.

34. The instrument according toclaim 33, further comprising,

a delay timing device for controlling a delay time between the point of time at which a defined minimum pressure force is applied and the triggering of the puncturing movement.

35. The instrument according toclaim 8, wherein the pressure ring has a mean width of at least about 0.5 mm and at most about 3.5 mm.

36. The instrument according toclaim 8, wherein the pressure ring has a mean width of at least about 0.7 mm and at most about 2.5 mm.

37. The instrument according toclaim 8, wherein the pressure ring has a mean width of at least about 0.8 mm and at most about 1 mm.

38. A lancing system for producing a body fluid sample analysis by piercing the skin, the system comprising:

a reusable hand-held-instrument comprising,

a housing,

a lancing drive within the housing connected to a lancing element and for driving a lancing element connected thereto in a puncturing movement in which the lancing element moves, after triggering the puncturing movement, in a puncture direction until it reaches a point of maximum displacement and in a reverse direction after it has reached the point of maximum displacement,

a pressure ring surrounding a skin contact opening and adapted for being pressed against the skin such that the skin bulges into the skin contact opening for promoting expression of body fluid, and

a holding device for holding an analysis element in the housing such that a body fluid sample is transported thereto from the sample collection device for analysis; and

a lancing element interchangeably connected to the drive of the instrument.

39. The lancing system according toclaim 36, wherein the lancing element is a part of an integral lancing and analysis element.

40. The lancing system according toclaim 36, wherein the lancing element is a direct sampler having a capillary channel for transporting the body fluid produced by piercing the skin by capillary flow to a sample collection zone thereof.

41. The lancing system according toclaim 36, further comprising,

a fluid communication device such that body fluid sample can be transferred from a sample collection zone of the lancing element to the analysis element for analysis.

42. The lancing system according toclaim 39, wherein the fluid communication device is switchable between a first configuration where no fluid communication is provided and a second position wherein fluid communication is provided.

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