Applicator for subcutaneous analyte sensor insertion

Abstract

A subcutaneous analyte sensor applicator is provided. The applicator includes a lancet, an ortho-planar insertion spring and a sensor. The lancet disposed within a housing configured to travel along a strike path. The ortho-planar insertion spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional firing form having energy stored therein to drive the lancet along the strike path. When in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet. When in the extended three-dimensional firing form the ortho-planar insertion spring is extended in a third / height dimension that extends along the strike path. The sensor is electronically and / or communicatively coupled with sensor electronics for determining an analyte within the body of a user.

Description

[0001] PROT.P-010-WO Title:

[0002] Applicator for Subcutaneous Analyte Sensor Insertion

[0003] Related Applications:

[0004] The present application is a non-provisional application of and claims the benefit of and priority to US Prov. App. Ser. No. 63 / 745,911 (PROT.P-010-PV1) filed on January 16, 2025, which is incorporated herein by reference for all purposes.

[0005] Field Of Invention:

[0006] The present invention relates to applicators and other devices for facilitating attachment or otherwise applying of monitors to a body of a user including implantation of a sensor under the skin of a user. The monitors may determine and / or measure analytes (e.g. potassium, sodium, and / or glucose) in the body of the user. The present disclosure further relates to methods of using such applicators for applying analyte monitors and design features thereof.

[0007] Background of the Invention:

[0008] Monitoring analytes levels in the human body can be important for various diagnostic reasons. For example, monitoring analytes (such as sodium, potassium, glucose, magnesium, chloride, lithium, calcium, bicarbonate etc.) levels is important for individuals suffering from various health related conditions.

[0009] Analyte monitors, and in particular, potassium monitors for monitoring potassium levels for the management of kidney disease, are being developed. Although there are few to no platforms for monitoring many analytes, including potassium, currently available on the market, it is envisioned that there will be in the future and there is a need to improve precision, wearability, and accessibility to end-users. In addition, there is a desire to provide robust applicator tools that can facilitate easy, consistent, low pain, low error, reproducible and effective application of an analyte monitor to a user’s body, and in particular, continuous analyte monitors which may be attached to the user’s body and worn for a prolonged period of time.It has been found that applicator designs of the art do not properly account for forces applied to the skin of a user by the applicator during operation and resulting effects caused by these forces. These forces can occur at various stages of applicator operation including during storing insertion energy into an insertion mechanism (e.g. an insertion spring), releasing insertion energy from the insertion mechanism to propel sharp (e.g. a lancet) and associated sensor toward the skin of the user, the skin-penetrating force and geometry of the lancet, storing retraction energy in a retraction spring, releasing stored retraction energy in the rection spring to retract the lancet from the skin of a user, etc.

[0010] Using applicators of the art, some or all of these forces are combined and applied at various vectors to the skin of a user during operation. When these forces are applied to the skin of a user, they can lead to various problems including larger-than-necessary wound size and tissue damage, unreliable sensor / lancet release and / or positioning within the user, and failure to satisfactorily adhere external components of the monitor to the skin. Improvement in all of these problem areas, and others, of the art is greatly desired.

[0011] Summary of the Invention:

[0012] The present invention solves the above-identified problems, inter alia, related to applicators of the past. In a first embodiment, the present invention provides a subcutaneous analyte sensor applicator including: a lancet disposed within a housing configured to travel along a strike path; a sensor electronically and / or communicatively coupled with sensor electronics for determining an analyte within the body of a user; and either or both (1) an ortho-planar insertion spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional firing form having energy stored therein to drive the lancet along the strike path, wherein: when in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet; and when in the extended three-dimensional firing form the ortho-planar insertion spring is extended in a third / height dimension that extends along the strike path AND / OR (2) an ortho-planar retraction spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional retraction form having energy stored therein to drive the lancet along the strike path,wherein: when in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet; and when in the extended three-dimensional retraction form the ortho-planar retraction spring is extended in a third / height dimension that extends along the strike path.

[0013] In a second embodiment, the present invention provides a subcutaneous analyte sensor applicator including: a lancet disposed within a housing configured to travel along a strike path; and a skin-tensioning member, wherein the skin-tensioning member comprises: a skin interaction surface comprising a polymeric material configured to interact with the skin to bulge the skin in a direction of the lancet on application of force applied to the applicator toward the skin of a user; and / or a skin interaction surface comprising a polymeric material configured to interact with the skin to grip the skin and apply force in a radial direction transverse to (e.g. normal and / or perpendicular to) the strike path, optionally wherein the radial direction transverse (e.g. normal and / or perpendicular to) to the strike path of the lancet is transverse (e.g. normal and / or perpendicular to) a U-shape channel of the lancet. In a third embodiment, the present invention provides a subcutaneous analyte sensor applicator including: a lancet disposed within a housing configured to travel along a strike path; an ortho-planar insertion spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional firing form having energy stored therein to drive the lancet along the strike path, wherein: when in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet; and when in the extended three-dimensional firing form the ortho-planar insertion spring is extended in a third / height dimension that extends along the strike path; an ortho-planar retraction spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional retraction form having energy stored therein to drive the lancet along the strike path, wherein: when in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet; and when in the extended three-dimensional firing form the ortho-planar insertion spring is extended in a third / height dimension that extends along the strike path; a trigger configured to interact with the insertion spring which is activated by applying a predetermined amount of force to the trigger alongthe strike path; a skin-tensioning member comprising: a skin interaction surface comprising a polymeric material configured to interact with the skin to bulge the skin in a direction of the lancet on application of force applied to the application toward the skin of a user; and / or a skin interaction surface comprising a polymeric material configured to interact with the skin to grip the skin and apply force in a radial direction to the strike path (optionally in a direction transverse a U-shaped channel of the lancet); and a sensor electronically and / or communicatively coupled with sensor electronics for determining an analyte within the body of a user.

[0014] In a fourth embodiment, the present invention provides methods of inserting a sensor into the skin of a user including the steps of: providing an applicator as described in any embodiment described herein; bringing the applicator in contact with the skin of a user; and inserting the sensor into the skin of a user.

[0015] Brief Description of the Drawings:

[0016] Fig. 1 shows an applicator in accordance with an embodiment of the present invention:

[0017] Fig. 2 shows a cross-sectional view of an applicator in accordance with an embodiment of the present invention

[0018] Figs. 3A to 3C show internal components parts of an applicator in accordance with an embodiment of the present invention.

[0019] Figs. 4A and 4B show an insertion spring in accordance with an embodiment of the present invention.

[0020] Figs. 5A, 5B, 6A and 6B show tile and tile holder interaction within an applicator embodiment of the present invention.

[0021] Figs. 7 A to 7C show lancet and lancet holder interaction within the applicator.

[0022] Figs. 8 shows lancet interaction and skin tensioning forces in accordance with an applicator embodiment of the present invention.

[0023] Figs. 9A to 9C show tile and lancet loading interaction in accordance with an applicator embodiment of the present invention.Fig. 10 shows internal components of an additional applicator design in accordance with the present invention.

[0024] Fig. 11 shows a skin tensioning element applied to the skin.

[0025] Fig. 12 shows an axisymmetric and non-axisym metric skin tensioning element applied to the skin.

[0026] Detailed Description:

[0027] The present invention solves inter alia above-identified problems found in applicators of the past. The applicator, monitor, and methods described herein, make use of strategies and mechanisms which decouple operational forces of the applicator and strategically employ certain operational forces to achieve desired effects at specific sequences of operation. These advancements will be described in the exemplary and non-limiting embodiments provided below.

[0028] In a particularly preferred embodiment, and as shown in Fig. 1, and in cross-sectional view in Fig. 2, an applicator 1 is provided to implement subcutaneous insertion of an analyte sensor into the skin and within interstitial fluid of a user. As shown and described in the figures and description below, applicator 1 contains inter alia a force activated trigger, insertion mechanism, retraction triggering mechanism, and retraction mechanism as well as additional components for tensioned the skin at or near the insertion site, tile holding mechanism, and a skin-penetrating lancet. The applicator contain several features disposed with a housing defining an internal strike path of the lancet which extends from toward one end of the housing and toward a second end of the house wherein when the applicator / lancet is in a tissue penetrating state, a tissue-penetration portion of the lancet extends past a skin contacting portion of the applicator. Figure 10 shows an exploded isometric view of internal components of an additional applicator design embodiment having components similar to those described herein.

[0029] Tile on tile loader:

[0030] As shown in Fig. 9A, a user receives a tile 16 packaged on a tile loader 20, where the tile 16 is lightly held in position by an adhesive patch 19 on the bottom of the tile16. As shown in Figs. 9A to 9C, the tile 16 is preloaded with a lancet 17, containing a sensor 21 to be inserted into the user’s skin.

[0031] Loading mechanism:

[0032] Using indicators (not shown) on the applicator 1 and tile loader the applicator 1 (Fig.1 ) is brought into alignment with the tile loader 20 (Fig. 9A) by the user and pressed vertically downwards. During this action an insertion spring (6 in figures 4A and B) is loaded from its relaxed state as shown in Fig. 4A to its loaded state shown in Fig. 4B. At the same time and in a similar fashion, the retraction spring (15 Fig. 2) is loaded and both are locked into position once the applicator 1 (Fig. 1) is fully depressed onto the tile loader 20 (Fig. 9A).

[0033] A tile holder (13 in Fig 5B) contains an orifice 127 (Fig. 5B) through which the lancet coupler (17 in Fig. 7B) moves during this motion, enabling locking of the lancet coupler onto a lancet clip (10 in Fig. 7A), within the applicator 1 (Fig. 1). The locking occurs due to spherical protrusions (119 in Fig. 7A) on a clip which aligns with corresponding indents 118 (Fig. 7b) on lancet 17. As the applicator 1 (Fig.1) is pressed further, tile 19 pushes up against the tile holder (13 in Figure 5B); grooves 112 (Fig. 6A) present on the tile latch (14 in Fig. 6A) connect with corresponding indents (137 in Fig. 6B) on the tile 16 enabling secure attachment between the tile 16 and the tile latch (14 in Fig. 6A).. The inner sleeve of the applicator 1 (Fig. 1) contains vertical guides (109 in Fig. 5A) and diagonal guides (110 in Fig. 5A) in which the tile latch prongs (111 in Fig 6a) fit into the diagonal guides 110, and the tile holder prongs (108 in Fig. 5B) fit into the vertical guides 109 and to align the lancet along the strike path of the applicator. The downward force applied by the use on the applicator results in an upward reaction force by the tile loader (20 in Fig. 9A)). This upward force is transferred by the tile 16 against the tile holder (13 in Figure 5B) causing the tile latch (14 in figure 6A) to rotate and slot associated grooves (112 in Fig. 6A) into the corresponding indents (137 in Fig. 6B) on the tile.

[0034] Subsequently, the tile latch (14 in Fig. 6A) and the retraction latch (12 in Fig. 7C) become locked. These components are pulled upward (e.g. along the strike path of the lancet) as a unified body with the spring coupler (5 in Fig.2). The spring coupler 5 will engage and pull the insertion spring (6, Fig. 2) upwards (e.g. along the strikepath of the lancet) until the spring coupler 5 is locked into the trigger spring (3 in Fig.2). Accordingly, the insertion spring has now been moved from a relaxed state to an extended state and has energy stored therein to interact with and drive the lancet along the strike path to a tissue-penetrating position where a tissue penetrating portion of the lancet extends past the skin-contacting end of the housing.

[0035] The inner dome (4 in Fig. 2) provides structure to the trigger spring (3 in Figs. 2 and 3b), enhancing stability and aiding to avoid vertical movement, while also acting as a spacer between the insertion 6 and trigger spring 3. The locking of the spring coupler 5 into the trigger spring 3 preferably results in an audible indication which signifies that the applicator 1 is ready for use and the insertion spring 6 is now in a loaded state. Throughout this process, button (11 in Fig.2), outer dome (2 in Fig. 2), inner dome (4 in Fig. 2), spacer, outer sleeve and inner sleeve (9 in Fig.2) are vertically fixed and yield minimal to no movement.

[0036] Lancet Configuration and Sensor Mounting:

[0037] The lancet comprises an elongated metal structure capable of penetrating the skin of the user and for interaction with a sensor to deliver the sensor into interstitial fluid of a user. In preferred embodiments, the lancet comprises a rolled or bent metal formed into a channel of sufficient width and / or depth to retain a sensor filament in the channel (e.g. see the U-shaped and / or channelled profile of the lancet (17, Fig.

[0038] 8))

[0039] Sensor filament (21 in Fig. 9C) can be connected to measurement electronics with a suitable connection such as ZIF connector which provides both mechanical and electrical connection to electronics housed within the tile (16 in Fig. 6B). Or pressure based contact such as pogo pins (containing a spring that will expand two conductive tips) to create electrical contact between exposed conductor on a printed circuit board. Or any other suitable connector used in flexible PCB circuitry.

[0040] Electrical / communication connection and / or contact of the sensor filament to the measurement electronics can be made at the time of insertion and / or at the time of assembling and / or prepping the application (1 in Fig. 1) for sensor insertion.

[0041] The filament of the sensor is guided through a narrow channel in the tile body (136 in Fig. 9C), which ensures the filament is guided down the length of the lancet (117 inFig. 7B). In preferred embodiment, the sensor filament is flexible and because of the orientation of the guide channel associates with the lancet (e.g. pushes itself into the U-shaped and / or channelled profile of the lancet (17, Fig. 8)).

[0042] In preferred embodiments, the tip of the sensor filament (21 in Fig. 9C) is located just behind the highest point of the ramp region of the lancet tip (126 in Fig. 9C). This ensures that the hole punctured in the skin is as wide as possible but also the full length of the filament below the tile is inserted into the skin.

[0043] Skin pre-tensioning and Firing:

[0044] The Inventors have discovered that the tension of skin can be a useful factor in determining and applying insertion force necessary for the lancet to penetrate the skin of a user. Accordingly, methods have been discovered and described herein that can be used alone or in combination to allow for pre-tensioning of a user’s skin prior to and / or during the lancet strike from the applicator to insert the sensor into the user’s skin.

[0045] Method 1:

[0046] As shown in Fig. 11 , when the applicator is pressed downwards onto the skin, the skin is caused to bulge due to force application via skin tensioning element (18 in Fig. 2) causing the skin surrounding the insertion site to be gripped and stretched. The amount of force required (e.g. a predetermined amount of force applied to the trigger along the strike path) to release and trigger the applicator is controlled by the trigger spring, in turn affecting the amount of pre-tensioning on the skin.

[0047] Pushing the applicator onto the skin also causes the skin to bulge upwards into the applicator roughly 5.5. to 7.5 mm (e.g. roughly 6.5 mm). This distance depends on the properties of the skin (elasticity, hydration, the shape and size of the opening in the base of the applicator, etc.).

[0048] Method 2:

[0049] In a second aspect of skin pretensioning as seen in Fig. 12, the applicator mechanism can pull the skin apart (e.g. stretches the skin) in a non-axisymmetric or axisymmetric manner.In the present embodiment, in use the applicator is pressed against the skin of a user with skin tensioning element (18 in Fig. 2). At least a portion of the force used to press the applicator 1 onto the skin in a direction along the strike path of the lancet to release the trigger spring (3 in Fig. 3B), is translated into a skin-stretching force that is radial / transverse to the strike path of the lancet (17 in Fig. 7B) (e.g. preferably transverse to a U-shaped channel of the lancet).

[0050] The skin tensioning member (18 in Fig. 2), can be made of a compliant material (e.g. TPU, PDMS, or other dermatologically-acceptable polymers and / or rubbers) capable of gripping and stretching the skin about the insertion site. In preferred embodiments, the skin stretching should be substantially normal to the U-shaped profile of the lancet (126 in Fig. 8, see arrows). In other embodiments the skin tensioning member 18 can be made of a material (such as a polymeric material) which exerts high friction with the skin. Polymeric materials includes those selected from the group consisting of: thermoplastic polyurethane (TPU), viton, nitrile, rubber, ethylene propylene diene monomer rubber (EPDM) , styrene-butadiene rubber (SBR), silicones / textured materials such as polydimethylsiloxane (PDMS), and other materials which achieve the same effect of gripping the skin for a given downward compression force.

[0051] Both the amount of pre-tensioning applied to the skin, and the compression applied to the applicator 1 is useful in defining a minimum insertion force required to puncture the skin. The combination of ferees also can define, in part, a starting position of the lancet 126 relative to the skin’s surface, and accordingly can define, in part, a stroke length and depth of insertion of the lancet 126 and corresponding sensor depth (i.e. Maximum depth of the lancet, and the force the spring will apply at the point of first contact with the skin).

[0052] Firing the Applicator:

[0053] Tension and compression on a user’s skin can be controlled by the applicator 1 through tuning of the spring force of the trigger spring (3 in Figure 3B).

[0054] As force is applied downward onto the top of the applicator 1, the button (11 in Fig.

[0055] 3A) is forced onto trigger spring (3 in Fig. 3B). The angle of the underside of the button (100 Fig. 3A), and the top of the trigger spring (101 in Fig. 3B), determineshow far the button must be depressed before ledges on the trigger spring (102 in Fig.

[0056] 3B), are forced apart, thus releasing spring coupler (5 Fig. 3C). The force required to perform this action can be determined by stiffness of the trigger spring which is defined by the number, angle, cross section, and material of construction of the arms (103 in Fig. 3B).

[0057] Once the spring coupler, 5, is released it is pulled downwards towards the skin by the insertion spring (6 Figs. 4A and 4B). This spring is shown in its unloaded (e.g. relaxed) and loaded positions in 4A and 4B respectively. Use of an ortho-planar spring, 6, allows for injection moulding, and precise tuning of its spring stiffness through the number of arms, thickness and width, and material of construction of these arms. The stroke length of insertion can be defined by the displacement of spring, 6, during loading and the force it applies at any given point in the stroke is defined by Hookes law. Thus the force applied by the tip of the lancet (17 Fig. 7B), can be defined by the stiffness of this insertion spring, 6, and the location of the skin relative to the position in the insertion stroke.

[0058] Due to the planar resting / relaxed positions of the insertion spring (6 in Fig. 4A) and retraction spring (15 in Fig. 2), manufacturing can be simplified as compared to more complex spring configurations and geometries. The ortho-planar spring forms as provided by the present invention can be FDM 3D printed, laser cut from flat sheets of cast polymers or metal, or injection moulded with relatively simple mould designs. Furthermore, providing insertion springs, 6, and retraction springs, 15, in an initial planar relaxed form (Fig. 4A) prior to applicator use can prevent creep and spring force decay over time during prolonged periods of applicator shipping / storage and adverse conditions such as elevated / reduced temperature and / or humidity often incurred during storage and / or shipping.

[0059] Spring coupler (5 in Fig. 3C), can be connected to the tile holder (13 in Fig. 5B), by latches on both parts (104 and 107 in Figs. 3C and 5B, respectively). As the insertion spring 6, drives the tile holder 13 towards the skin it is guided by vertical slots 109 in inner sleeve 9. The tile (16 Fig. 6B) is located in tile holder (13 in Fig. 5b) by ridges 116 ensuring the tile does not rotate relative to the lancet, 17, during insertion or lancet retraction.During insertion, the tile (16 Fig. 6B) is held securely against the tile holder (13 in Fig. 5B) by the tile latch (14 in Figure 6A). Two ledges (112 in Fig. 6A) in the tile latch 14, fit into corresponding grooves 137. As the tile holder 13 is driven downwards, tile latch 14 is forced to rotate as posts 111 are guided by slots 110. The typical tile latch rotation is from about 15 to 45 degrees (e.g. about 30 degrees). Tile latch 14 rotation allows the tile free movement out of the applicator at completion of the insertion stroke. This rotation also triggers retraction latch, 12 figure 7c. The retraction latch 12 is a bi-stable switch. This mechanism uses a shuttle which is held by four arms 124. The two preferred positions of this mechanism are in the horizontal plane. The bi-stable nature of this mechanism ensures it is fully engaged, or disengaged.

[0060] The bi-stable switch has two stable positions, either engaged or not engaged with the lancet clip, 10. The bi-stable switch uses ledges 123 to retain the lancet clip 10. At a specified point in the insertion stroke, the bi-stable switch is triggered which releases the lancet clip, 10. The lancet clip, 10, is then pulled upwards away from the skin by a second ortho-planar spring (e.g. a retraction spring). The stiffness and geometry of the retraction spring defines, at least in part, the force at which the lancet, 17, is removed from the skin. Lancet 17, includes a channelled shaft 117 (e.g. a Il-formed metal shaft), with a plastic moulded head. Lancet 17 is retained in lancet clip 10 by the spherical protrusions 119 which align with corresponding indentation 118 in lancet 17. The wedge-shaped region at the top of the lancet head, 120, acts to force the two arms of the lancet clip, 121 , apart during loading.

[0061] The U-shaped shaft of lancet 117 fits into a corresponding aperture (e.g. here a U-shaped groove 114) in tile 16. The tip of lancet 17 is defined primarily by two angles including tip angle 125 and ramp angle 126. The tip angle 125 is a useful parameter in defining the minimum insertion force required to puncture the skin. During insertion there will be a slight deviation in the angle of the force profile as the transition from the flat region of the tip 17 to the angled region of the ramp 126. This ramp in combination with the speed of insertion can define the rate at which the puncture site in the skin is opened. Control of this angle can influence the amount of trauma caused at the insertion site and the formation of a small flap of skin within the U-shaped region of the lancet 117.Once inserted the lancet is pulled vertically upwards through the tile (113 in Fig. 6B). The rigidity of the flexible sensor filament is sufficient to maintain it’s position in the skin. This rigidity is related to the cross-sectional profile of the sensor filament, it’s material construction (e.g. Polyimide) and the angle it is bent through.

[0062] The retracted lancet is now hidden from the user within the tile holder 13. This helps to mitigate risk of a sharps injury from the now used lancet. Once the insertion of the lancet 17 is complete the filament of the sensor 21 protruding from the base of the tile 16 interacts with the user’s tissue to reside within the hole formed by the lancet 17 in the skin. During retraction the lancet 17 is rapidly removed, the sensor 21 decouples from the lancet 17, and the sensor filament 21 remains in the skin.

[0063] Retraction:

[0064] In certain embodiments, during motion of the tile holder 13 toward the base of the applicator 18 after the initial trigger button 11 push, the retraction spring 15 is extended downwards from its initial planar configuration (Fig. 4A) (relaxed configuration) to an extended configuration / three dimensional configuration ( Fig. 4B)(energized configuration where refraction force is stored in the retraction spring). In other embodiments, energy is stored in the retraction spring 15 when energy is stored in the insertion spring 6 during tile loading.

[0065] Upon reaching the base of the applicator 18, the tile holder 13 comes into contact with the skin, and the retraction latch opens releasing retraction energy stored in the retraction spring 15 causing upward movement and withdrawal of the lancet 17 upon completion of the sensor insertion strike and deployment of tile 16 on the skin of the user. After lancet removal, the retraction spring 15 contracts back toward its original position and toward its original planar configuration similar to that of the relaxed spring shown in Fig. 4A, pulling the lancet 17 and associated clip 10 upward and out of and away from the skin of the user. The lancet tip 17 is then effectively shielded within the applicator 1 from the user, preventing any contact with the pierced tip 17. Once retracted the user may dispose of the entire applicator 1 if it is intended as a single use device. Alternatively, the tile holder (13 in Fig. 5B), which now encapsulates the used lancet 17, could be removed by the user and disposed of, and a new tile and tile holder 13 and lancet 17 can be inserted into the applicator 1 ,thereby making the applicator 1 ready for and suitable for reuse. If the applicator 1 is configured for reuse, it is preferred that it be reused between 2 and 20 times (e.g. 10 times or less) to limit spring creep (e.g. reduction in spring force over time / use) so as to ensure sufficient insertion 6 and retraction spring 15 reusability. In such an embodiment, a firing counter may be employed to count the number of applicator firings and / or render the reused applicator 1 inoperable after a predetermined amount of firings.

[0066] Release of Tile and Applicator from the User’s Skin:

[0067] After the applicator 1 has been fired and the sensor 21 deployed in the skin of a user, the user moves the applicator 1 away from the skin, completing the transfer process between the tile 16 / sensor 21 and the user. The adhesion force between the tile adhesive 19 and the user’s skin overcomes frictional surface force between the tile 16 and associated holder 13, allowing for tile transfer and effective removal of the applicator 1.

[0068] The tile 16 is held against the skin by a suitable adhesive, such as an adhesive patch 19. In a particularly preferred embodiment, the adhesive patch 19 includes a nonwoven polyester backing (129 Fig. 9C) one side coated with 3M proprietary silicone adhesive (130 Fig. 9C) for repositionable attachment to skin. The other side of the polyester backing is coated with a high tack adhesive, 128 Fig. 9C.

[0069] Sensor and tile electronics:

[0070] The sensor filament 21 residing within the user’s body is configured for providing a signal representative of a desired analyte level in the user. The tile 16 comprises hardware and programmed circuitry comprising logic and instructions for receiving signals from the sensor 21 and providing wireless communications via a wireless communication protocol (e.g. bluetooth or some other near field communication protocol) to a receiver (such as a router, a node, cellular network tower, and / or personal computing device such as a tablet, PC or smartphone) and / or some other network (such as a local area network, cellular network, and / or the world wide web). In certain embodiments, signals from the sensor 21 can be partially and / or fully processed within the tile 16 to correlate sensor signals to values representative ofanalyte levels in the user. In other embodiments, the tile 16 receives and transfers unprocessed sensor signals to the receiver and / or network.

[0071] Hardware present in the tile 16 preferably comprises a power source (such as a battery) for powering tile 16, sensor 21 and / or wireless communication electronics. In some embodiments, the tile 16 may further comprise a display for displaying sensor and / or analyte level data and / or other information to a user.

[0072] In preferred embodiments, the power source and / or tile 16 and / or sensor 21 are present in a deep sleep state or otherwise electrically decoupled until near, or at the time, the sensor 21 and / or tilel 6 is brought into contact with the user’s skin / interstitial fluid and / or priming the device for firing (e.g. loading the tile into the applicator and / or storing energy in the insertion spring). In these embodiments, decoupling electronics or allowing a deep sleep of such electronics allows for extended shelf life and / or allows for certain types of shipment. In these embodiments, electrical and / or communicative contact between the power source and / or the sensor 21 and / or tile electronics can be made (or the power source and / or tile 16 can be awakened from a deep sleep state) upon triggering the insertion force of the applicator 1 and / or by movement of the lancet 17 and / or sensor filament 21 toward the skin of a user. For example, as the lancet 17 and / or sensor 21 pass through the tile 16, as described above, electrical and / or communicative contact can be made between any and / or all of tile electronics, sensor electronics, and / or the power source.

[0073] Making electrical and / or communicative contact between sensor electronics and tile electronics can be done using:

[0074] (a) pressure based contact such as pogo pins (containing a spring that will expand two conductive tips) to create electrical contact between exposed conductor on a printed circuit board;

[0075] (b) connectors with mechanical housing to securely connect a cable to a printed circuit board; and / or

[0076] (c) epoxy based technique using a conductive glue to secure an electrical connection between printed circuit boards or between printed circuit board and a wire.In additional embodiments, sensor measurement procedures (e.g. power on the tile / sensor, from a deep sleep state) can be done:

[0077] (d) during the application process, a connection between 2 parts of the electrical components can be broken (temporarily or permanently); (e) during the application process, a connection between 2 parts of the electrical components can be established (temporarily or permanently); (f) during the application process, a magnetic field can be generated or modified near an electrical component (temporarily or permanently), (e.g. with the use of a magnet); and

[0078] (g) a Bluetooth Low Energy signal can be received from the smartphone (the device can wake up periodically - every 15 minutes - and monitor BLE activities).

[0079] Decoupling of Forces:

[0080] During insertion of a sensor filament 21 into the skin there are a number of forces involved.

[0081] (1) The amount of compression force applied to the applicator 1 is translated from the applicator 1 to the skin around the insertion site. This is related to the amount of tension applied to the skin at the insertion site and depends, at least in part, on the geometry of the skin interaction portion / bottom of the applicator (e.g. preferably axisymmetric, such as a circle of some diameter). There may also be tension applied in one preferred direction. The coefficient of friction of the skin interaction portion / bottom of the applicator will also have an impact on the magnitude of this friction. In preferred embodiments, the skin interaction portion / based on the applicator will comprise a polymeric material (e.g. dermatologically acceptable polymer / rubber) which can grip the skin to increase the skin tension achieved for a given downward compression force.

[0082] (2) The greater the skin tension the more the hole opened by the puncture site will open potentially leading to more successful sensor insertions, but this may also result in more skin trauma. In preferred embodiments, the present invention provides an optimal level of skin tension which should be achieved. In the applicator of the present invention, the optimal level of skin tension ispreferably provided and controlled by the force required to activate the trigger spring 3, and the material used as the skin interaction portion / base of the applicator 18 (a polymeric I rubber like material).

[0083] (3) The force required to puncture the skin can be related to the shape and sharpness of the tip 17 and the speed of insertion.

[0084] (4) The force required to retract the lancet 17 from the skin can be dependent on the amount of surface area of the lancet 17 in contact with the skin and the coefficient of friction between the lancet 17 and skin.

[0085] (5) The force required to ensure correct adhesion between the adhesive patch 19 and the skin can be dependent on the size of the tile 16, the type of adhesive, effective area of contact with the skin, and the condition of the skin. For example, it has been found that in some embodiments, skin that has not been pretensioned has less effective surface area to interact with the adhesive as compared to pretensioned skin which has more effective surface area to interact with skin. Accordingly, the present Inventors have discovered that tile adhesion (as well as lancet and sensor insertion) to a user’s skin can be improved when the skin is pretensioned in accordance with the present invention as compared with tile adhesion using applicators and methods of the prior art.

[0086] The magnitude of these forces is dictated by different underlying factors and thus are not strongly dependent on each other. Hence, using separate mechanisms within an applicator to produce each (or some combination) of these forces (e.g. decoupling of operational forces) enables the design of the present applicator which provides the optimal force required for and at each stage of the insertion process. The present inventors have found that this leads to a higher rate of successful insertions, less pain and skin trauma to the user, and longer lasting tile / sensor adhesion to the skin of a user.

[0087] Prior to the present invention, it was not known how to disentangle and / or decouple these different forces from one another via use of a single applicator. In the present invention, disentanglement and / or de-coupling of these forces is achieved by employing springs with force vectors in one axis (vertically or along the lancet strike path) versus skin stretching, latching and trigger mechanisms in other directions(radially about the vertical axis or strike path). According to some embodiments, a single triggering mechanism that requires one concrete force applied (vertically or along the strike path), results in a series of separate and fine tuned forces that execute each of the individual tasks without interfering with each other.

[0088] Firing and Retraction Spring Form and Forces:

[0089] In some embodiments, both the insertion 6 and retraction springs 15 are of roughly similar two-dimensional and / or ortho-planar form, shown in Fig. 4A, when present in a relaxed state, and are of roughly similar three-dimensional extended form when present in an active or stored-energy state / form, shown in 4B. In these embodiments, the insertion 6 and retraction springs 15 are ortho-planar springs configured to interact with the lancet to move (e.g. drive / retract) the lancet along a strike path of the applicator. When present in a relaxed state, the springs reside generally in a plane which extends substantially perpendicular / normal to the strike path while the thickness of the springs extend some amount parallel to / along the strike path. When present in an extended state / form with retraction / insertion energy, respectively, stored therein the springs are considered to be in a three-dimensional / energized / stored-energy form where the springs are extended along the strike path to store energy and / or release stored energy sufficient to move the lancet along the strike path. Typically, a lower force is required for lancet retraction from the skin than for lancet insertion. Thus, the retraction spring 15 is typically of a smaller outer diameter, thinner cross-section, and / or smaller arms resulting in a lower spring force being generated as compared to the insertion spring 6.

[0090] In certain embodiments, both insertion 6 and retraction springs 15 are loaded when the user pushes the applicator 1 down onto the tile loader 20. In other embodiments, the insertion spring 6 is loaded with energy (extends from its planar relaxed state to an extended three-dimensional firing state) when the user pushes the applicator 1 onto the tile loader 20. In some embodiments, upon release of the insertion spring 6 from its extended three-dimensional firing state, energy stored in the insertion spring 6 drives the lancet 17 toward the skin of a user while causing extension of, and storing energy in, the retraction spring 15 for subsequent use in retraction of the lancet 17 from the skin of the user. In these embodiments, it is contemplated the energy stored in the insertion spring 6 must be equal to or greater than (for example5%, 10%, 20%, 30% or more than) the forces necessary to drive the lancet 17 into the skin of a user, drive the tile 16 in contact with the skin of a user, and store energy in the retraction spring 15 for subsequent retraction of the lancet 17 from the skin of the user.

[0091] In a further embodiment, the present invention also provides a method of inserting a sensor into the skin of a user. The method includes the step of providing and bringing the applicator of any embodiment, or combination of embodiments, described herein into contact with skin of a user, and inserting the sensor into the skin of the user.

[0092] Reference throughout the specification to “one embodiment,” “another embodiment,” “an embodiment,” “some embodiments,” “aspect”, and so forth, means that a particular element (e.g., feature, structure, property, and / or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described element(s) and / or feature(s) of any embodiment may be combined in any suitable manner with any other described embodiments.

Claims

Claims:(1) A subcutaneous analyte sensor applicator comprising:a lancet disposed within a housing configured to travel along a strike path; an ortho-planar insertion spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional firing form having energy stored therein to drive the lancet along the strike path, wherein: when in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet; and when in the extended three-dimensional firing form the ortho-planar insertion spring is extended in a third / height dimension that extends along the strike path; anda sensor electronically and / or communicatively coupled with sensor electronics for determining an analyte within the body of a user.(2) The applicator of claim 1, wherein the analyte is selected from the group consisting of: potassium, sodium, and glucose.(3) The applicator of claim 1, wherein the lancet comprises a U-shaped channel extending along a length of the lancet which extends along the strike path, and wherein the sensor is disposed in at least a portion of the u-shaped channel.(4) The applicator of claim 1, further comprising an ortho-planar retraction spring configured to extend from a relaxed planar form to an extended three-dimensional retraction form, wherein: when in the relaxed planar form the ortho-planar retraction spring resides in a plane that is substantially normal to the strike path; and when in the extended three-dimensional retraction form the ortho-planar retraction spring is extended in a third / height dimension that extends along the strike path.(5) The applicator of claim 4, wherein the energy stored in the ortho-planar insertion spring in its extended three-dimensional firing form is sufficient to drive the lancet along the strike path to puncture the skin of a user, and to extend the ortho-planar retraction spring from its relaxed planar form to its extended three-dimensional retraction form to store retraction energy in the retraction spring.(6) The applicator of claim 1, further comprising a skin-tensioning member.(7) The applicator of claim 6, wherein the skin-tensioning member comprises: a skin interaction surface comprising a polymeric material configured to interact with the skin to bulge the skin in a direction along the strike path of the lancet on application of force applied to a trigger.(8) The applicator of claim 7, wherein the applicator further comprises the trigger configured to interact with the insertion spring which is activated by applying a predetermined amount of force to the trigger along the strike path;(9) The applicator of claim 6, wherein the skin-tensioning member comprises a skin interaction surface comprising a polymeric material configured to interact with the skin to grip the skin and apply force in a radial direction and transverse to the strike path, and optionally wherein the radial direction to the strike path of the lancet is transverse a u-shape channel of the lancet.(10) The applicator of claim 1 , further comprising an electronics tile communicatively and / or electrically coupled with the sensor, wherein when the lancet is disposed within the skin of a user, the electronic tile is attached to the skin of a user.(11) The applicator of claim 10, wherein when the electronic tile is brought into contact with the skin of a user, the sensor is electrically and / or communicatively coupled with the electronics tile.(12) The applicator of paragraph 11 , wherein upon retraction of the lancet from the skin of a user, the lancet is drawn with the housing of the applicator.(13) A subcutaneous analyte sensor applicator comprising:a lancet disposed within a housing configured to travel along a strike path; anda skin-tensioning member, wherein the skin-tensioning member comprises: a skin interaction surface comprising a polymeric material configured to interact with the skin to bulge the skin in a direction of the lancet on application of force applied to the applicator toward the skin of a user; and / or a skin interaction surface comprising a polymeric material configured to interact withthe skin to grip the skin and apply force in a radial direction transverse to the strike path, optionally wherein the radial direction transverse to the strike path of the lancet is transverse a U-shape channel of the lancet.(14) An subcutaneous analyte sensor applicator comprising:a lancet disposed within a housing configured to travel along a strike path; an ortho-planar retraction spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional retraction form having energy stored therein to drive the lancet along the strike path, wherein: when in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet; and when in the extended three-dimensional retraction form the ortho-planar retraction spring is extended in a third / height dimension that extends along the strike path; anda sensor electronically and / or communicatively coupled with sensor electronics for determining an analyte within the body of a user.(15) The applicator of claim 14, wherein a retraction spring loading force is required to extend the retraction spring from the relaxed planar form to the extended three-dimensional retraction form, and wherein the loading force is provided by an insertion spring upon insertion of the lancet into the skin of a user or during loading of an insertion spring.(16) A subcutaneous analyte sensor applicator comprising:a lancet disposed within a housing configured to travel along a strike path;an ortho-planar insertion spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional firing form having energy stored therein to drive the lancet along the strike path, wherein: when in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet; and when in the extended three-dimensional firing form the ortho-planarinsertion spring is extended in a third / height dimension that extends along the strike path;an ortho-planar retraction spring configured to interact with the lancet and to extend from a relaxed planar form to an extended three-dimensional retraction form having energy stored therein to drive the lancet along the strike path, wherein: when in the relaxed planar form the ortho-planar insertion spring resides in a plane that is substantially normal to the strike path of the lancet; and when in the extended three-dimensional firing form the ortho-planar insertion spring is extended in a third / height dimension that extends along the strike path;a trigger configured to interact with the insertion spring which is activated by applying a predetermined amount of force to the trigger along the strike path; a skin-tensioning member comprising: a skin interaction surface comprising a polymeric material configured to interact with the skin to bulge the skin in a direction of the lancet on application of force applied to the application toward the skin of a user; and / or a skin interaction surface comprising a polymeric material configured to interact with the skin to grip the skin and apply force in a radial direction to the strike path (optionally in a direction transverse a II- shaped channel of the lancet); anda sensor electronically and / or communicatively coupled with sensor electronics for determining an analyte within the body of a user.(17) A method inserting a sensor into the skin of a user comprising the steps of: providing an applicator as described in claim 1 ;bringing the applicator in contact with the skin of a user; andinserting the sensor into the skin of a user.

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