Patent Application
20110092854
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:
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:
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.
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.
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:
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 to
If the sample collection device 36 is a part of an analysis element 21, or of an integrated lancing and analysis element 22, 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, the sample collection device 36 can be separate from the reaction zone of the analysis element 21 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 the sample collection device 36 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 the sample collection device 36 to the reaction zone of the analysis element 21 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 the sample collection device 36 to the analysis element 21 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 to
The degree of target site bulging 6, i.e., the distance d between the plane of pressure ring 1 and the apex of target site bulge 6, can be influenced by many factors such as, for example, the size of the skin contact opening 4, the pressing force F and the viscoelastic properties of the skin 3. These factors can further depend on a plurality of other aspects including, for example: (1) the elasticity of the skin 3 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 finger 2, 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 skin 3; and (4) skin 3 treatment preceding the lancing, such as washing with soap, disinfecting etc.
Generally, the skin contact opening 4 can be substantially circular. In one embodiment, the skin contact opening 4 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 opening 4 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 opening 4 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 opening 4 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 opening 4, the area of the skin contact opening 4 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 opening 4 can be at least about 3 mm. In another embodiment, the smallest inner, free width of a non-circular skin contact opening 4 can be at least about 4 mm.
As noted above, in the prior art, the uncertainty about the actual z-position of the skin 3, i.e., the apex of the target site bulge 6, has either been disregarded or has been taken into account by measuring or referencing the actual skin 3 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 opening 4 and the amount of the pressing force F are maintained.
In one exemplary embodiment, best shown in
In one embodiment, the lancet drive 14, shown in
After triggering of a puncture movement, by a triggering method, the drive rotor 29 can turn with high speed, driven by a drive spring, about its axis 35. This rotational movement can be translated by a cam curve formed by groove 30 and traveled by cam traveler 31 into a corresponding pivoting movement of drive rod 32 which again can drive a corresponding up and down movement of lancing element 12 to which it can be connected by its coupling protrusion 26 penetrating into coupling recess 24. Similar drive rotor 29 for lancing instruments 11 are known in the art, therefore, no more detailed description may be necessary.
In the exemplary embodiment shown in
During lancing, the lancing element 12 can perform a puncturing movement by which piercing tip 7 can be driven into skin 3. Thereafter, during a retraction phase of the puncturing movement, after the piercing tip 7 has reached its point of maximum displacement P but with the piercing tip 7 still below the surface of skin 3, a body fluid sample can penetrate, driven by capillary forces, into the capillary channel 28 and reservoir chamber 28a. Thus, the capillary 28 and reservoir chamber 28a together can form a sample collection device 36 suitable for storing body fluid sample, ready for subsequent transfer to an analysis zone 8 of analysis element 21.
Once the body fluid sample arrives at sample collection zone 23, it may be transferred to the adjacent analysis zone 8 of analysis element 21 by a suitable fluid communication device. In one embodiment, the arrangement can be such that there can beno fluid communication between the sample collection zone 23 of lancing element 12 and the analysis element 21. 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 pressing sample collection zone 23 of lancing element 12 and analysis element 21 together.
Alternatively, the present disclosure can also be used with integral lancing and analysis elements 22 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 lancing element 12 holding device and as analysis element holding device.
While devices for holding and moving a lancing element 12 and an analysis element 21, or an integral lancing and analysis element 22, in the instrument 11 have been described, many other suitable devices can be possible. Such devices can include, for example, a design in which analysis elements 21 and/or lancing elements 12 can be fixed to and transported by means of a tape during at least a part of the lancing system 10 operation.
In one embodiment, the pressing force F acting at the time of triggering the puncturing movement between the pressure ring 1 and the skin 3 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 ring 1 and the skin 3 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 ring 1 and the skin 3 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 pressing force control device 37. The limiting values of the pressure force can be with respect to the requirements of withdrawing sample from the skin 3.
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 ring 1 and the skin 3 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 ring 1 and the skin 3 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 ring 1 and the skin 3 during the MITP may be no more than about +/−0.2 N.
In one exemplary embodiment, the pressing force control device 37 can be mechanical, in particular, it can comprise a spring device 38 which can be arranged in such a manner that its spring force can act between the pressure ring 1 and the housing 13. In one embodiment, the spring device 38 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 any such spring device 38. In one exemplary embodiment, the spring device 38 can be pre-tensioned.
In one exemplary embodiment, pressing force control devices 37 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 ring 1 may be pressed against the skin 3 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 pressing force control device 37 provided in the instrument 11. In this embodiment, the pressing force control device 37 can comprise a spring 38 which can be embodied and arranged in such a manner that one end thereof can act against pressure ring 1 and the other end can act against the housing 13. 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 ring 1 and that the corresponding counter-force can be, directly or indirectly, borne by the housing 13.
In one embodiment, the instrument 11, shown in
In one exemplary embodiment, when a user presses her or his finger tip 2 in the direction of arrow F onto pressure piece 42 with pressure ring 1, the latter can move downwardly against the force of spring 38, or other spring device 38 known in the art. As soon as the contact between pressure piece 42 and the housing 13 at pressure ring bearing 43 is interrupted, the force of spring 38 can be balanced by the pressing-down force of the finger 2. In other words, the force by which the pressure ring 1 may be pressed against the skin 3 can be in this status controlled by the pressing force control device 37, such as, for example, by a spring 38.
The elastic spring 38 can increase linearly with its elongation, i.e., compression in the case of a compression spring as shown. In one exemplary embodiment, the pressure ring 1 pressed against the skin 3 can be controlled closely, i.e., the variation thereof may not exceed the preferred limiting values. In this exemplary embodiment, the spring 38 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 ring 1, i.e., the pressure ring 1 is in its “home” position resting on the surrounding wall, bearing 43, of housing 13. In one exemplary embodiment, the degree of this pre-tensioning can be such that the force of spring 38 acting on the pressure ring 1 can vary by no more than about 20% within the spring-loaded movement range of the pressure ring 1. In another exemplary embodiment, the force of spring 38 acting on the pressure ring 1 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 finger 2, or other body part, and the pressure ring 1 can be controlled only by the force of spring 38 balanced by the pressing-down-force of finger 2. This condition may not be met if the movement of pressure ring 1 was influenced or limited by some kind of abutting member or obstacle acting, within its possible movement range, on ring 1. In order to meet this condition, a pressure ring movement limiting arrangement 44 (see
In one exemplary embodiment, shown in
It may be favorable for the maximum displacement P of the pressure ring 1 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 ring 1 and the adjacent housing 13 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 ring 1 versus the adjacent housing 13 area can simplify the finding of a suitable finger 2 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 ring 1 may be non-deformable in the sense that it may not be visibly deformed during normal use of the lancing system 10. A suitable exact shape and width of the pressure ring 1 can be determined experimentally. In one embodiment, the pressure ring 1 can have a width of at most about 3.5 mm. In another embodiment, the pressure ring 1 can have a width of at most about 2.5 mm. In yet another embodiment, the pressure ring 1 can have a width of at most about 1 mm. In one embodiment, the pressure ring 1 can have a minimum width of about 0.5 mm. In another embodiment, the pressure ring 1 can have a minimum width of about 0.7 mm. In yet another embodiment, the pressure ring 1 can have a minimum width of about 0.8 mm. The pressure ring 1 may protrude from any adjacent housing 13 surface by a sufficient distance to allow easy tactile recognition thereof by the user.
Of course, the pressure ring 1 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 the particular instrument 11, can contact the skin 3 surface. Of course, this ring-shaped contact surface (i.e., the pressure ring 1) 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 skin 3 can have interruptions such as, for example, recesses, which may, however, be small enough not to spoil the described function of the pressure ring 1.
Excellent reproducibility of the z-position of the skin bulge 6 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 opening 4 and concerning the force by which the pressure ring 1 and the skin 3 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 lancing system 10. The lancing system 10 can work without a z-position detection and without a penetration depth reference element adapted for contacting the skin 3 which can bulge into the pressure ring 1.
The starting point of the MITP can be a point in time at which the lancing system 10 may be “ready for lancing”, i.e., the lancing drive 14 may be ready for driving a lancing movement of a lancing element 12 connected thereto and the desired lancing site of the skin 3 may be properly located at the skin contact opening 4 of the instrument 11. Depending on the design of the lancing system 10, 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 the instrument 11, for example for detecting the skin 3 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 lancing system 10 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 skin 3 which may take place after establishing a pressure force between the skin 3 and the pressure ring 1.
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 the sample collection device 36 of the instrument 11 for analysis. A “sample collection device” 36 as used herein can be any part of the lancing system 10, inside the instrument 11, 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 lancing system 10. However, in another embodiment, the instrument 11 can comprise a MITP controlling device 17. This term can refer to any device which can help ensure that the required interaction between the user and the instrument 11, i.e., the required pressing force F between the skin 3 and the pressure ring 1, is maintained by the user at least during the MITP. In other words, the MITP controlling device 17 can provide assistance to ensure that the actual interaction between the user and the instrument 11 overlaps, or at least coincides with, the MITP.
The MITP controlling device 17 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 device 17 can comprise detecting the starting point of the MITP, by detecting the pressing force F acting between a pressure ring 1 and the skin 3 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 device 17 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 finger 2 on a spring-supported pressure ring 1 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, the instrument 11 may have a fill control, as part of the MITP controlling device 17, 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 the instrument 11 using a fixed MITP value (depending on the design of the lancing system 10 components).
Advantages can be achieved with integrated lancing and analysis systems 10 if the pressing force F between the pressure ring 1 at the distal end of the lancing instrument 11 and the skin 3 is maintained, not only at the time of lancing, but, also, for a short interaction period thereafter: (1) With both types of integrated lancing and analysis systems 10, 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 the instrument 11, i.e., its skin contact opening 4, relative to the skin 3 can be fixed until the point of time that the analysis device can be moved to the skin contact opening 4; 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 in
In the lancing system 10 illustrated in
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 opening 4, it can be even possible to design an instrument 11 with no user-setable penetration depth adjustment. Surprisingly, with a single factory-set z-position of the lancet drive 14, point of maximal displacement, and of the pressure ring 1, 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 the instrument 11.
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 skin 3 position, it may be sufficient to provide interchangeable distance elements or pressure rings 1 to allow a single adaption of the lancing systems 10 to the needs of a particular user.
In general, the instrument 11 and lancing system 10 can take into account the viscoelastic properties of the skin 3 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.
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.
