The present invention relates to a lancing device. It particularly relates to a lancing device for use with a lancet assembly and integrated with a test meter.
Lancing devices are typically used in the medical field to lance or break the surface of the skin on a finger, in order to extract a small blood sample for self diagnostic purposes. This may involve inserting a test strip into an analytical meter, puncturing one's finger tip with a lancing device to obtain a droplet of blood, transferring the droplet of blood onto a test element on the test strip, and checking a reading on the analytical meter for the concentration of a single analyte in the droplet of blood. The analyte may be blood glucose for a person with diabetes, cholesterol for a person with cardiovascular condition, uric acid for a person with gout, drug for monitoring effect of a therapy or presence of illegal drugs, and so on. Often, such diagnoses are repeated several times in a day and providing a diagnostic tool that is easy to operate and yet giving a less painful, if not a painfree, experience is desired.
For example, good diabetes management requires frequent monitoring of blood glucose level through self-testing. Self-testing of blood glucose is important, as it enables people with diabetes to know their blood glucose level at any time, hence allowing them to exercise tighter blood glucose control. This will help to prevent any potentially serious consequences of very high or very low blood glucose level. It is especially crucial for people who take insulin, as self-testing will allow more accurate dosage adjustment.
A lancing device is a critical tool for obtaining blood samples for glucose measurement. The primary mechanism of most lancing devices currently existing in the market, both for repeated use and disposable lancet types, involve priming a spring-based system, followed by a release of a trigger to launch the lancet or needle into the finger of the user. In this way, the lancet or needle is made to puncture a tiny hole on the finger of the user to obtain a blood sample for diagnostic purposes.
Such lancing devices generally convert potential energy from the primed spring into the kinetic energy of a moving lancet and its holder at the same time. This kinetic energy is then dissipated through impact of the lancet and its holder against a rigid stop. The rigid stop is also often used as a way of defining the depth of penetration of the needle into the finger. In most cases, potential energy from another spring is used to reverse the motion of the lancet, hence withdrawing it from the finger after the hole has been punctured.
It is quite typical to hear complaints from users of the lancing devices with design described above, in relation to pain during lancing process. This could be attributed to some of the following reasons. The lancing mechanism hitting at a hard stop at maximum velocity would cause excessive impact vibration, which will then be transmitted to the lancet. The excessive relative vibration and movement between needle and finger is likely the cause of the pain experienced by user.
Another cause of pain during lancing is an uncontrolled lancing motion of the lancet, which will result in an unpredictable trajectory of the needle during lancing process. This uncontrolled motion refers to the ability of the lancet and its holder to move within the sliding clearance offered by its guides, which are often plastic molded features. In addition to that, impact noise is perceived as pain most of the time, since it forms part of the overall user experience. Devices with such lancing mechanism, which relies on impact to define the lancet's penetration depth and to reverse its motion, are often perceived by the user as being noisy and painful.
Examples of lancing device with a design intended to allow less painful blood withdrawal, may be seen in the following U.S. patents. U.S. Pat. No. 4,924,879 discloses a blood lancing device, which convert the relaxation movement of the drive spring by means of a rotatable drive rotor into the prick movement, hence allowing blood withdrawal with little or no pain. The vibration caused by the impact of the lancet holder onto a hard stop can then be avoided. The rotor is driven by a coaxial coil spring and the rotation movement of the rotor is converted to the linear movement of the lancet by means of a push rod system.
U.S. Pat. No. 5,318,584 discloses a lancing device with the drive rotor having a rotation axis parallel to the prick direction and is also driven by a coaxial coil spring. The conversion of the rotational movement into the necessary linear movement of the lancet holder is performed by a rotary drive. The design allows a very good pricking behavior with low vibrations and a reproducible pricking depth, hence resulting in less pain.
U.S. Pat. No. 4,203,446 discloses a spring lancet holder with improved accuracy and reproducibility of puncture wounds in the skins by minimizing the recoil transmitted to the lancet holder by actuation of the drive mechanism, which pushes the lancet into the skin.
U.S. Pat. No. 7,396,334, assigned to Roche Diagnostics Operations, Inc., describes a needle and lancet body integral with a test element. The accompanying figures show the tip of the needle is embedded in an elastic material whilst the drive end of the needle extends from the rear of the lancet body.
US Publication No. 2008/0262386, also assigned to Roche Diagnostics Operations, Inc., describes an analytical system for detecting an analyte in a body fluid, and a disposable integrated puncturing and analyzing element. The instrument is cheap to manufacture and allows a user full control over the individual steps in collecting a blood sample for analysis.
US Publication No. 2008/058631, assigned to Beckton Dickinson, describes a blood glucose meter having integral lancet device and test strip storage vial for single hand use. By combining these multiple components into a single device, the glucose meter requires fewer steps in its use.
Despite development in the art, there still exists a need for a device and method for analyzing a person's physiologic fluid for a medical condition that overcome the shortcomings of known devices.
According to a first aspect, there is provided lancing device for use with a lancet for obtaining a blood sample. The lancing device comprises a housing; a probe disposed in the housing; and a probe actuator for linearly displacing the probe. The probe is configured for releasably engaging a lancet. The probe is provided with sliding surfaces for slidably engaging a pair of guides; wherein each sliding surface has a radius of curvature centred about a curvature defining axis, the curvature defining axis being coincident with a central longitudinal axis of the lancet when the lancet is engaged by the probe; and wherein the sliding surfaces are continually biased against the pair of guides such that when the lancet is engaged by the probe, the lancet is prevented from translating in any other direction than in a direction parallel to its central longitudinal axis during linear displacement of the probe.
The pair of guides preferably comprises two sloped surfaces, each of the sloped surfaces being disposed on either side of the curvature defining axis.
The probe, the probe actuator and the pair of guides may be disposed on a base plate of the housing. The base plate is preferably moveable relative to the housing in a direction parallel to the central longitudinal axis of the lancet for adjusting the protrusion of the lancet from the lancet assembly during displacement of the probe when the probe is engaged with the lancet.
The lancing device preferably further comprises a second pair of guides and further sliding surfaces provided on the probe for slidably engaging the second pair of guides.
The probe actuator is preferably rotatable about a pivot disposed on the base plate of the housing with an axis of rotation perpendicular to the central longitudinal axis of the lancet.
The probe actuator preferably comprises a driving pin disposed at a distance from the axis of rotation for engaging a driving slot provided in the probe, the driving slot being configured such that rotation of the probe actuator in a driving direction results in linear displacement of the probe.
The lancing device may further comprise a priming slot provided in the probe for accommodating the driving pin therein during rotation of the probe actuator to a primed position, the priming slot being configured such that rotation of the probe actuator to the primed position results in no linear displacement of the probe.
The lancing device preferably further comprises a priming actuator for rotating the probe actuator to the primed position, a biasing element for biasing the probe actuator towards rotating in the driving direction, and an actuating button configured for releasing the probe actuator from the primed position such that when the actuating button is pressed, the probe actuator rotates in the driving direction under the bias of the biasing element.
The lancing device may further comprise means for minimizing vibration of the lancet during linear displacement of the probe when engaged with the lancet.
The housing is preferably configured for removably attaching a disposable lancet assembly thereto, the disposable lancet assembly comprising the lancet, and wherein the probe is configured for releasably engaging the lancet when the lancet assembly is attached to the housing.
The lancing device may further comprise an analyte test meter for determining concentration of an analyte in the blood sample.
According to a second aspect, there is provided a disposable lancet assembly for use with a lancing device. The lancet assembly comprises a casing configured for releasable attachment to a housing of the lancing device; a lancet contained in the casing, the lancet being configured for releasable engagement with a linearly displaceable probe of the lancing device, the lancet being moveable with respect to the casing when the lancet is engaged with the linearly displaceable probe; and a test strip disposed on the casing for receiving a blood sample thereon.
The disposable lancet assembly may comprise locking adaptations on the casing and on the lancet body for preventing egress of a tip of the lancet from the casing after use. The test strip may comprise a sensing end for receiving the blood sample and a terminal end for contacting sensing terminals of a test meter provided with the lancing device.
According to a third aspect, there is provided a lancing kit comprising the lancing device and the disposable lancet assembly mentioned above.
According to a fourth aspect, there is provided a method for determining an analyte in a blood sample. The method comprises inserting a lancet assembly into an integrated device comprising a lancing device and a test meter, the lancet assembly comprising a lancet disposed within a casing and a test strip disposed on the casing, said lancet and casing comprising locking adaptations for preventing egress of a tip of the lancet from the casing after use; actuating the lancing device to lance a finger with the lancet; collecting a blood sample from the lanced finger; transferring the blood sample onto the test strip and obtaining a reading from the test meter; and removing the lancet assembly from the integrated device and simultaneously locking the lancet within the casing.
Exemplary embodiments will now be described with reference to the accompanying drawings, by way of example only, in which:
a-b show lancet displacement profiles in z-x and z-y axes of the lancing device of
Description of embodiments of the present invention shall now be explained in detail, with reference to the attached drawings. It is to be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
Details of the configuration of the priming system are further illustrated in
The priming button or priming actuator 13 is connected to the rack 14 via screws connection, as illustrated in
Upon rotation of the probe actuator 15 to the primed position, the probe actuator 15, together with the torsion spring 16 where potential energy is stored, are locked in the primed position and will only be released once the fire button 17 is pressed. The compression spring 12 returns the priming button 13 and the priming gear 11 back to their original rest positions after the probe actuator 15 has been rotated to the primed position. Once the fire button 17 is pressed, stored potential energy in the torsion spring 16 is imparted to the probe actuator 15 to rotate the probe actuator 15 in a driving direction back to its rest position, preferably clockwise viewed from above. The torsion spring 16 thus serves as a biasing element for biasing the probe actuator 15 towards rotating in the driving direction.
Rotation of the probe actuator 15 in the driving direction linearly displaces a probe 10 with a cam profile 29 to which the probe actuator 15 is moveably engaged, resulting in forward sliding of the probe 10 together with a lancet 7 engaged by the probe 10 towards the skin of the user. As can be seen, the axis of rotation R-R of the priming gear 11 and probe actuator 15 is perpendicular to the central longitudinal axis C-C of the lancet 7 when the lancet 7 is engaged by the probe 10.
Referring to
The cam profile or driving slot 29 is responsible for regulating the speed of the lancet 7 when the lancet 7 is engaged by the probe 10 and the fire button 17 is pressed. The velocity profile of the lancet 7 is controlled by the cam profile 29. In other words, appropriate contouring of the cam profile 29 allows the related lancet displacement and velocity profile to be optimized for minimum pain and enhanced user compliance.
Preferably, the lancet 7 penetrates the skin relatively quickly but decelerates smoothly and gradually to zero velocity at a maximum depth of penetration into the target area on the finger, where nerve endings are abundant. Smooth transition to zero velocity and absence or reduction of vibration of the lancet 7 reduces pain to the user. Slow and controlled retraction of the lancet 7 prevents the wound channel from collapsing and allows blood to flow directly to the surface of the skin. This encourages rapid healing of the puncture wound and offers a less painful lancing experience to the user at the same time.
The connection between the damper 35, the probe actuator 15, the torsion spring 16 and the pivot or guide pin 21 of the bottom case or base plate 4 is further illustrated in
Besides the cam profile 29, the ratio of the damper 35 and the stiffness of the torsion spring 16 are other factors that determine the velocity profile of the lancet 7. It is preferred if the torsion spring 16 is not too stiff, as it will require more effort from the user to prime it. The use of a less stiff spring is compensated by proportionally reducing the damping provided by the damper. The damping effect can be appropriately adjusted by using a damper of different size. The cam profile 29 determines how much of the potential energy from the torsion spring 16 is converted to the kinetic energy of the lancet 7. In summary, the combination of the effect of different cam profile 29, different stiffness of the torsion spring 16 and different ratio of the damper 35 can be optimized for achieving desired velocity profile of the lancet 7.
As shown in
The sliding surfaces or the profile slides 32 and 33 have circular profiles whose centre axes coincide with that of the lancet centre. In other words, each of the sliding surfaces 32, 33 has a radius of curvature IT centred about a curvature defining axis CDA as shown in
Two pin connections 25 located on the bottom case or base plate 4 are provided for attachment of a leaf spring 26 each. The leaf springs 26 act on the probe 10 to bias the sliding surfaces 32 and 33 of the probe 10 against the guides 23 and 24, such that movement of the probe 10 in z-axis or in a direction perpendicular to the central longitudinal axis of the lancet 7 is eliminated or minimized during sliding or movement of the lancet 7 when engaged with the probe 10. The leaf springs 26 thus ensure that the probe 10 is always be in contact with the v-shaped profile guides 23 and 24 of the bottom case or base plate 4, thereby minimizing pitching of the lancet 7 during lancing, hence reducing pain.
As a result of the curvature defining axis CDA of the sliding surfaces 32, 33 being coincident with the central longitudinal axis C-C of the lancet 7, and also the action of the leaf springs 26 biasing the sliding surfaces 32, 33 against the guides 23, 24, the lancet 7 is prevented from translating in any other direction than in a direction parallel to its central longitudinal axis C-C during linear displacement of the probe 10. This will limit the probe movement, if any, to a slight minimum rotation of the lancet 7, instead of lateral movement of the lancet 7, thus reducing any pain experienced by the user to a minimum.
a-b show the comparison of the lancet displacement in z-x and z-y axes during the lancing process, between the lancing device of the present invention (
After lancing, the lancet is retracted from the skin of the user as the probe 10 slides backward as the cam follower 36 of the probe actuator 15 continues to move within the driving slot 29 along the cam profile 29 that is embedded or integrally formed in the probe 10. A top perspective view of the final assembly of the lancing device 1 according to the first exemplary embodiment of the invention is shown in
A second exemplary embodiment of a lancing device according to the present invention is shown in
As shown in
In use, the lancet 70 is disposed in the hollow casing 40 such that the free end of the L-shaped catch 82 engages with the end edge of the longitudinal slot 50 so that the lancet 70 becomes locked onto the casing 40 as one assembly. From
By providing an interference fit between the lancet body 76 and the collar 27 of the probe, there is no slipping of the lancet from the collar 27 and therefore the amount of travel of the needle pointed end 74 into a user's skin is substantially determined by the depth penetration mechanism. The interference fit between the lancet 70 and the collar 27 also ensures that substantial concentricity of the lancet 70 with the longitudinal axis 41 is maintained and the pointed end 74 of the lancet takes on the characteristic movement of the probe 10, in terms of displacement, velocity and acceleration as described above. The clearances between the lancet body 76 and the collar 46 and that between the lancet body 77 and the bore 43 also ensure that the pointed end 74 of the lancet takes on the characteristic movement of the probe 10.
In addition, when the lancet assembly 100 is fully inserted into the integrated device 170, sensing terminals T of the test meter provided in the integrated device 170 come into contact with and ride on the terminal end 62 of the lancet assembly 100. A tongue or rib Q at the receptacle R of the integrated device 170 as shown in
To discard the used lancet assembly 100, the user pulls on the lancet casing 40 to free the entire lancet 70 from the collar 27 whilst the L-shaped catch 82 is still disengaged. Once the lancet assembly 100 is removed from the receptacle R, the L-shaped catch 82 springs back to its locked position and thereby locks the used lancet 70 inside the casing 40 to prevent egress of the lancet tip 24 from the casing 40 after use. The relocking of the used lancet 70 into the casing 40 minimizes accidental pricking by the lancet tip 24. The L-shaped catch 82 and the longitudinal slot 50 thus form locking adaptations on the casing 40 and on the lancet body 76 for preventing egress of the lancet tip 74 from the casing 40 after use.
In this embodiment, the maximum projection of the needle pointed end 74 from the front face 42 of the casing 40 is given by the stroke S of the probe 10 minus L2.
Depending on the skin characteristics at the intended blood sampling point, for example, thickness and hydration of the epidermis, the depth of wound puncture is a function of S minus L2.
As with the lancet assembly 100, the fit between the collar 27 at the free end of the probe 10 (as shown in
When the lancet assembly 110 is inserted into the collar 27 of the probe 10 of the integrated device 170, a lead-in chamfer at the collar 27 pushes the catch 132 down into its cavity 133 and unlocks the catch 132 from the aperture 145. In the earlier embodiment, when the lancet assembly 100 is inserted into the collar 27, the lancet 70 is in contact with the integrated device 170 through the spigot Q and the L-shaped catch 32. In this embodiment, when the lancet assembly 110 is inserted into the collar 27, the lancet 120 does not contact any part of the test meter 7.
After firing of the probe 10, the probe 10 returns to its unprimed position and the lancet 120 is withdrawn into the casing 140. To discard the used lancet assembly 110, the user pulls on the lancet casing 140 to free the entire lancet assembly 110 from the collar 27. As the user pulls on the lancet casing 140, the end-face 143a of the slot 143 in the casing 140 engages the stopper 134 on the lancet body 126, thereby pulling the lancet 120 out of the collar 27 on the probe 10. Once the lancet 120 is removed from the collar 27, the catch 132 springs back to its inactivated or locked position and projects into the aperture 145 of the casing 140 to lock the used lancet 120 inside the casing 140. The aperture 145 and the catch 132 thus form locking adaptations on the casing 140 and on the lancet body 126 for preventing egress of the lancet tip 124 from the casing 140 after use. Locking the used lancet 120 inside the casing 140 thus minimises accidental pricking by the needle 122 and thus allows for safe disposal of the used lancet assembly 110.
The stopper 134 shown in
A further preferred alternative embodiment of an integrated device 370 according to the present invention is shown in
However, the probe 210 is further provided with a priming slot 230 for accommodating the driving pin 236 therein during rotation (preferably anti-clockwise) of the probe actuator 215 to the primed position. The priming slot 230 is configured such that during rotation of the probe actuator 215 to the primed position, there is no linear displacement of the probe 210, thereby eliminating the possibility of the lancet tip displacing to accidentally prick the user while the lancing device is being primed for use. This is achieved by shaping the priming slot 230 as a curved slot 230 having a radius of curvature r that is the same as the distance d that the driving pin 236 is displaced from the axis of rotation R-R of the probe actuator 215.
In the preferred alternative embodiment shown in
The integrated device 370 similarly is provided with two pairs of guides 223 and 224 preferably having a v-shaped profile disposed on the front and rear part of the base plate 204 for locating the probe 210 thereon. Each pair of guides 223 and 224 comprises two sloped surfaces facing upwardly and inwardly for slidably engaging sliding surfaces or profile slides 232 and 233 provided on the probe 210.
Each of the sliding surfaces 232, 233 has a radius of curvature rr centred about a curvature defining axis CDA as shown in
As a result of the curvature defining axis CDA of the sliding surfaces 232, 233 being coincident with the central longitudinal axis C-C of the lancet 307, and also the action of the leaf springs 226 biasing the sliding surfaces 232, 233 against the guides 223, 224, the lancet 307 is prevented from translating in any other direction than in a direction parallel to its central longitudinal axis C-C during linear displacement of the probe 210.
The lancet 307 has a lancet body 326 and a lancet tip 324. A cap 378 is integrally molded with the lancet body 326 for encapsulating the lancet tip 324. As shown in
Locking adaptations 373 are preferably provided on the lancet body 326 and on the casing 340 for preventing egress of the lancet tip 324 from the casing 340 after use. The locking adaptations 373 may comprise cantilever arms as shown in
To allow for adjusting maximum displacement of the lancet 307 from the lancet assembly 300 during displacement of the probe 210 when the probe is engaged 210 with the lancet 307, the base plate 204 may be configured to be moveable relative to the housing 302 in a direction parallel to the central longitudinal axis C-C of the lancet 307. Maximum depth penetration of the lancet 307 can then be set to a desired level by the user moving the base plate 204 to an appropriate position along the housing 302. This controls the extent of protrusion of the lancet tip 324 from the casing 340 during lancing.
An advantage of using an integrated lancing and testing device 170, 370 (comprising a test meter and the lancing mechanism of the device of
In contrast, in the present invention, the number of steps required to conduct an analysis of one's blood sample, as shown in
Although the number of steps have been reduced, there is no substantive change that a user has to learn in using the analyte test device 170, 370 of the present invention. Another advantage of the present invention includes relocking of a used lancet 20,120, 307 inside the casing 40,140, 340 so that the used lancet assembly 100,110, 300 can be disposed of in a safe manner. When using a conventional lancing device, the skin puncture point is close to the lancet cover and periodic cleaning of blood stains is necessary. With the present invention, the relative distance from the skin puncture point and integrated device 170 is greater than the skin puncture point to the conventional lancing device, so there is little likelihood of blood stain on the test meter; thus, there is no need for periodic cleaning to remove blood stains off the test device. In addition, as the lancing mechanism is provided together with the test meter in the integrated device 170, 370, there is no additional cleaning of a separate lancing device; if there is blood stain, it is likely to appear on the used lancet devices 100,110, 300, which are disposed of. The unused lancet assemblies 100,110, 300 together with the test strips 60, 360 are preferably kept in an air-tight container in compliance with manufacturer's directions so that reliability of the test strips is maintained.
Another advantage of the present invention is that it allows a user control over the individual steps in collecting a blood sample. For example, a user may be used to milking one's finger to ooze out a droplet of blood. The user of the present invention is able to do so after firing the lancing mechanism in the integrated device 170370; once a sufficient amount of blood has been oozed out, the blood droplet is transferred onto the analyte sensing end 64, 364 of the test strip 60, 360. In the event of a user not being able to obtain a sufficient amount of blood when using some known diagnostic devices, for example a fully automatic diagnostic device, the device has to be primed again to make another skin puncture and often resulting in a test strip being wasted; instead, with the present invention, the user can milk one's finger to obtain a sufficient amount of blood or re-prime the lancing mechanism to make another skin puncture, albeit deeper penetration, without wasting the lancet assembly 100,110, 300 that has been inserted into the integrated device 170, 370.
It should be appreciated that the invention has been described by way of example only and that various modifications in design and/or detail may be made without departing from the scope of this invention. For example, the probe actuator could be configured such that the priming direction and the driving direction are both rotation in the same direction, i.e., both clockwise or both anti-clockwise. Instead of the probe actuator being a rotating actuator biased by a torsion spring and engaging the driving slot on the probe, the probe actuator could comprise an electric linear actuator directly attached to the probe. Instead of two separate sliding surfaces being provided on the probe for engaging a pair of guides on the base plate as shown in the figures, a single continuous curved surface may be provided for engaging the pair of guides such that two areas forming two sliding surfaces on the single curved surface contact the pair of guides. Besides providing a damper or a spring to minimize vibration of the lancet during linear displacement of the probe when engaged with the lancet, other appropriate means such as a resilient foam may be used.
Number | Date | Country | Kind |
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12327817 | Dec 2008 | US | national |
12407796 | Mar 2009 | US | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/SG2009/000468 | 12/4/2009 | WO | 00 | 7/13/2011 |