System for applying an on-skin sensor assembly to a recipient's skin - Patents.com

Abstract

To provide systems and methods for enabling reliable, simple and pain-minimizing transcutaneous insertion of an analyte.SOLUTION: Systems for applying a transcutaneous monitor to a person can include a telescoping assembly, a sensor, and a base with an adhesive to couple the sensor to skin. The sensor can be located within the telescoping assembly while the base protrudes from a distal end of the system. The system can be configured to couple the sensor to the base by compressing the telescoping assembly.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] Interactive Incorporation of Related Applications Any and all priority claims or any amendments thereto identified in the Application Data Sheet are incorporated herein by reference under 37 CFR 1.57. This application claims the benefit of U.S. Provisional Application No. 62 / 272,983, filed December 30, 2015, and U.S. Provisional Application No. 62 / 412,100, filed October 24, 2016. Each of the foregoing applications is incorporated herein by reference in its entirety, and each of which is expressly incorporated herein by reference.

[0002] Various embodiments disclosed herein relate to measuring analytes in a person. Certain embodiments relate to systems and methods for applying a transdermal analyte measurement system to a person. [Background technology]

[0003] Diabetes mellitus is a disorder in which the pancreas cannot make enough insulin (type I or insulin-dependent) and / or insulin is ineffective (type 2 or non-insulin-dependent). In the diabetic state, sufferers suffer from hyperglycemia, which can lead to a series of physiological disorders associated with microvascular deterioration, such as kidney failure, skin ulcers, or bleeding into the vitreous of the eye. Hypoglycemic reactions (hypoglycemia) can be caused by inadvertent overdosing of insulin, or by extreme exercise or inadequate food intake after regular dosing of insulin or glucose-lowering drugs.

[0004] Traditionally, a person with diabetes carries a self-monitoring blood glucose monitor, which typically requires an uncomfortable finger prick method. Due to lack of comfort and convenience, a person with diabetes usually only measures their glucose levels two to four times a day. Unfortunately, such time intervals are spread out so far apart that a person with diabetes may not know about a hyperglycemic or hypoglycemic condition until it is too late, sometimes resulting in dangerous side effects. Glucose levels can alternatively be continuously monitored by a sensor system that includes an on-skin sensor assembly. The sensor system can have a transmitter that transmits measurement data to a receiver, which can process and display information based on the measurements.

[0005] The process of applying a sensor to a person is important to making such a system effective and user friendly: the application process allows the sensor assembly to be attached to a person with the sensor assembly capable of sensing glucose level information, communicating the glucose level information to a transmitter, and transmitting the glucose level information to a receiver.

[0006] The analyte sensor may be placed into subcutaneous tissue. A user may actuate the applicator to insert the analyte sensor into its functional location. This percutaneous insertion may lead to incomplete sensor insertion, improper sensor insertion, needle exposure, or unnecessary pain. Thus, a need exists for a system that more reliably enables percutaneous sensor insertion while being easy to use and relatively painless. Summary of the Invention

[0007] Various systems and methods described herein enable reliable, simple, and minimally painful transdermal insertion of an analyte. Some embodiments are systems for applying an on-skin sensor assembly to the skin of a recipient. The system can include a nesting assembly having a first portion configured to move distally relative to a second portion along a path from a proximal start position to a distal position, a sensor module coupled to the first portion, the sensor module including a sensor, electrical contacts, and an encapsulant, and / or a base coupled to the second portion to protrude from a distal end of the system. The base can include an adhesive configured to couple the sensor module to the skin. Moving the first portion to a distal position can couple the sensor module to the base. The sensor can be an analyte sensor, a glucose sensor, any sensor described herein or incorporated by reference, and / or any other suitable sensor.

[0008] In some embodiments (i.e., optional and capable of being independently combined with any of the aspects and embodiments identified herein), the sensor module can include a sensor module housing. The sensor module housing can include a first flex arm.

[0009] In some embodiments (i.e., optional and capable of being independently combined with any of the aspects and embodiments identified herein), the sensor can be positioned within the second portion while the base protrudes from the distal end of the system such that the system is configured to couple the sensor to the base via moving the first portion distally relative to the second portion.

[0010] In some embodiments (i.e., optional and capable of being combined independently with any of the aspects and embodiments identified herein), the sensor can be coupled to the sensor module while the first portion is positioned in the proximal starting position.

[0011] In some embodiments, the needle is coupled to the first portion (of the nesting assembly) such that the sensor and needle move relative to the base and distally relative to the second portion. The system can include a needle release mechanism configured to proximally retract the needle.

[0012] In some embodiments, the base includes a distal projection having a first hole. The distal projection can be configured to reduce resistance of the skin to puncture. The sensor can pass through the first hole in the distal projection.

[0013] In some embodiments, a needle having a slot passes through a first hole in the distal projection, and a portion of the sensor can be positioned in the slot such that the needle is configured to move distally relative to the base without displacing the portion of the sensor out of the slot.

[0014] In some embodiments, the distal protrusion is convex such that the distal protrusion is configured to apply tension to the skin while the first portion is moving distally relative to the second portion to prepare the skin for piercing. The distal protrusion can be dome-shaped.

[0015] In some embodiments, the adhesive comprises a second hole and the distal projection can be positioned at least partially within the second hole such that the distal projection can apply tension to at least a portion of the skin underlying the second hole.

[0016] In some embodiments, the adhesive covers at least a majority of the distal protrusions. The adhesive can cover 0 percent, at least 30 percent, at least 70 percent, and / or less than 80 percent of the distal protrusions. The distal protrusions can protrude at least 0.5 millimeters, less than 3 millimeters, and / or less than 5 millimeters.

[0017] In some embodiments, the sensor module is coupled to the first portion while the first portion is in the proximal start position and is positioned at least 3 millimeters and / or at least 5 millimeters from the base, and the system can be configured such that moving the first portion to a distal position couples the sensor module to the base.

[0018] In some embodiments, the sensor is already coupled to the sensor module while the first portion is positioned in the proximal start position. For example, the sensor can be coupled to the sensor module at the factory (e.g., before the user opens the sterility barrier). The sensor can be positioned within the second portion while the base protrudes from the distal end of the system.

[0019] In some embodiments, the sensor is coupled to a sensor module. The sensor module can be immobile relative to the first portion during a first portion of the path, and the base can be immobile relative to the second portion. The system can be configured to move the first portion distally relative to the second portion during the second portion of the path, move the sensor module toward the base, couple the sensor module to the base, and enable removal of the coupled sensor module and base from the nested assembly.

[0020] In some embodiments, the sensor module is coupled to the sensor. The system includes a vertical central axis oriented from the proximal end to the distal end of the system. The sensor module can include a first flex arm oriented horizontally and coupled to the base. The first flex arm can extend from a periphery of the sensor module.

[0021] In some embodiments, the base comprises a first proximal protrusion coupled to the first flexible arm to couple the sensor module to the base. The first horizontal locking protrusion can be coupled to an end portion of the first flexible arm. The second horizontal locking protrusion can be coupled to the first proximal protrusion of the base. The first horizontal locking protrusion can be positioned distally below the second horizontal locking protrusion to secure the sensor module to the base. The system can be configured such that moving the first portion of the nested assembly to a distal position bends the first flex arm to allow the first horizontal locking protrusion to move distally relative to the second horizontal locking protrusion.

[0022] In some embodiments, the base includes a second proximal protrusion coupled to a second flex arm of the sensor module. The first flex arm can be positioned on an opposite side of the sensor module relative to the second flex arm.

[0023] In some embodiments, the sensor module is coupled to the sensor. The system can include a vertical central axis oriented from the proximal end to the distal end of the system. The base can include a first flex arm oriented horizontally and coupled to the sensor module. The sensor module can include a first distal protrusion coupled to the first flex arm to couple the sensor module to the base.

[0024] In some embodiments, a first horizontal locking protrusion is coupled to an end portion of the first flexible arm and a second horizontal locking protrusion is coupled to a first distal protrusion of the sensor module, the second horizontal locking protrusion being positioned distally below the first horizontal locking protrusion to secure the sensor module to the base. The system can be configured such that moving a first portion of the nestable assembly to the distal portion bends the first flex arm to allow the second horizontal locking protrusion to move distally relative to the first horizontal locking protrusion.

[0025] In some embodiments, the sensor module includes a second distal protrusion coupled to a second flex arm of the base. The first distal protrusion can be positioned on an opposite side of the sensor module relative to the second distal protrusion.

[0026] In some embodiments, the sensor module is coupled to the sensor. The first portion can include a first flex arm and a second flex arm that protrude distally and latch onto the sensor module while the first portion is in the proximal start position to releasably secure the sensor module to the first portion. The sensor module can be positioned remotely from the base (e.g., such that the sensor module does not contact the base) while the first portion is in the proximal start position.

[0027] In some embodiments, the sensor module is positioned within the second portion while the base protrudes from a distal end of the system such that the system is configured to couple the sensor module to the base via moving the first portion distally relative to the second portion.

[0028] In some embodiments, the system comprises a vertical central axis oriented from the proximal end to the distal end of the system. The first and second flex arms of the first portion can secure the sensor module to the first portion such that the sensor module is releasably coupled to the first portion with a first vertical retention strength. The sensor module can comprise a third flex arm coupled to a first proximal protrusion of the base such that the sensor module is coupled to the base with a second vertical retention strength.

[0029] In some embodiments, the second vertical retention strength is greater than the first vertical retention strength such that continuing to push the first portion distally once the sensor module is coupled to the base overcomes the first and second flex arms of the first portion to remove the sensor module from the first portion. A third flex arm can extend from a perimeter of the sensor module.

[0030] In some embodiments, the base protrudes from the distal end of the system while the first portion of the nestable assembly is positioned in a proximal start position, and the sensor is positioned remotely relative to the base such that the system is configured to couple the sensor to the base via moving the first portion distally relative to the second portion. The base can include a first radial protrusion releasably coupled to a second radial protrusion of the second portion of the nestable assembly with a first vertical retention strength.

[0031] In some embodiments, the first radial protrusion protrudes inwardly and the second radial protrusion protrudes outwardly. The system can be configured such that moving the first portion to the distal portion moves the second radial protrusion relative to the first radial protrusion to remove the base from the nested assembly.

[0032] In some embodiments, the first portion of the nestable assembly includes a first arm projecting distally and the second portion of the nestable assembly includes a second flex arm projecting distally, and the system is configured such that moving the first portion along the path from a proximal start position to a distal position causes the first arm to deflect the second flex arm, thereby disengaging the second flex arm from the base and allowing the base to decouple from the nestable assembly. When the first portion is in the proximal start position, the first arm of the first portion can be at least partially vertically aligned with the second flex arm of the second portion to allow the first arm to deflect the second flex arm as the first portion moves to the distal position.

[0033] In some embodiments, when the first portion is in a proximal start position, at least a section of the first arm is positioned directly over the second flex arm, allowing the first arm to deflect the second flex arm as the first portion moves to a distal position.

[0034] In some embodiments, the second flex arm includes a first horizontal protrusion and the base includes a second horizontal protrusion that is latched with the first horizontal protrusion to couple the base to the second portion of the nested assembly. The first arm of the first portion can deflect the second flex arm of the second portion to unlatch the base from the second portion of the nested assembly.

[0035] In some embodiments, the system is configured to couple the sensor to the base at a first location, and the system is configured to detach the base from the nested assembly at a second location distal to the first location.

[0036] In some embodiments, the third flex arm couples the sensor to the base in a first position and the second flex arm detaches from the base in a second position, the second position being distal to the first position such that the system is configured to secure the base to the nested assembly until after the sensor is secured to the base.

[0037] In some embodiments, the base protrudes from the distal end of the system while the first portion of the nestable assembly is in a proximal start position and the sensor is positioned remotely relative to the base. The system may further include a spring configured to store a needle. The needle may be configured to facilitate inserting the sensor into the skin. The spring may be in a first compressed state when the first portion is in the proximal start position. The system may be configured such that moving the first portion distally from the proximal start position further increases compression of the spring. The first compressed state places the first and second portions in a tensioned state.

[0038] In some embodiments, the system is configured to apply an on-skin sensor assembly to the skin of a recipient (i.e., a person). The system can include a nesting assembly having a first portion configured to move distally relative to a second portion along a path from a proximal start position to a distal position, a sensor coupled to the first portion, and / or a latch configurable to prevent the needle from moving proximally relative to the first portion. The sensor can be an analyte sensor, a glucose sensor, any sensor described herein or incorporated by reference, and / or any other suitable sensor.

[0039] In some embodiments, the first portion is releasably secured in the proximal start position by a securing mechanism that prevents the first portion from moving distally relative to the second portion. The system can be configured such that moving the first portion distally relative to the second portion releases the latch prior to reaching the distal position, thereby allowing the needle to be retracted proximally into the system. The system can be configured such that moving the first portion distally relative to the second portion (e.g., moving the first portion to the distal position) releases the latch, thereby allowing the needle to be retracted proximally into the system. The securing mechanism can be an interference between the first and second portions of the nested assembly.

[0040] In some embodiments, a first force profile is measured along the path and can comprise a first magnitude corresponding to overcoming the locking feature, a third magnitude corresponding to unlatching, and a second magnitude corresponding to an intermediate portion of the path distal to overcoming the locking feature and proximal to unlatching.

[0041] In some embodiments, the second magnitude is less than the first and third magnitudes such that the system is configured to facilitate acceleration of the needle during an intermediate portion of the path to allow for an adequate needle velocity (e.g., a sufficiently high needle velocity) when the needle initially pierces the skin.

[0042] In some embodiments, the first magnitude is at least 100 percent greater than the second magnitude. The first magnitude can be greater than the third magnitude such that the system is configured to prevent initiation of a sensor insertion cycle unless a user applies sufficient force to release the latch. The first magnitude can be at least 50 percent greater than the third magnitude.

[0043] In some embodiments, the intermediate portion of the pathway is distal to overcoming the locking mechanism and proximal to releasing the latch. The system can further comprise a second force profile that coincides with the intermediate portion of the pathway. In response to compressing a spring configured to allow the system to retract the needle into the nested assembly, a proximal millimeter of the second force profile can comprise a lower average force than a distal millimeter of the second force profile.

[0044] In some embodiments, a first force profile is measured along the path. The first force profile can comprise a first average magnitude consistent with moving distally past a proximal half of the fixation mechanism and a second average magnitude consistent with moving distally past a distal half of the fixation mechanism. The first average magnitude can be greater than the second average magnitude such that the system is configured to prevent the system from initiating a sensor insertion cycle (e.g., driving the needle and / or sensor to an intended insertion depth) unless the user applies sufficient force to complete the sensor insertion cycle.

[0045] In some embodiments, the first force peak (coincident with moving distally past the proximal half of the fixation mechanism) is at least 25 percent higher than the second average magnitude.

[0046] In some embodiments, a first force profile is measured along the path. The first force profile can comprise a first magnitude consistent with overcoming the fixation mechanism and a subsequent magnitude consistent with stalling the fixation mechanism. The first magnitude can comprise a proximal vector and the subsequent magnitude can comprise a distal vector.

[0047] In some embodiments, the fixation mechanism can include a radially outer protrusion extending from the second portion. The radially outer protrusion can be positioned proximally relative to a proximal end of the second portion while the nestable assembly is in the proximal start position. The radially outer protrusion can be configured to deform the first portion into an elliptical shape to allow the first portion to move distally relative to the second portion.

[0048] In some embodiments, the fixation mechanism comprises a radially outer protrusion of the first portion that interferes with a radially inner protrusion of the second portion such that the fixation mechanism is configured to deform the second portion into an elliptical shape, allowing the first portion to move distally relative to the second portion.

[0049] In some embodiments, the needle is retractably coupled to the first portion by a needle holder configured to resist distal movement of the first portion relative to the second portion. The locking mechanism can include a flexible arm on the second portion. The flexible arm can be releasably coupled to the needle holder to releasably lock the first portion to the second portion at the proximal start position.

[0050] In some embodiments, the fixation mechanism comprises a frangible bond between the first and second portions while the first portion is in the proximal start position, and the system can be configured such that moving the first portion to the distal position breaks the frangible bond.

[0051] In some embodiments, the locking mechanism comprises a magnet that releasably couples the first portion to the second portion while the first portion is in the proximal start position. The magnet can be attracted to a metal element coupled to the first portion or the second portion of the nestable assembly.

[0052] In some embodiments, the electric motor drives the first portion distally relative to the second portion. The electric motor can be configured to move the needle into the skin.

[0053] In some embodiments, an on-skin sensor system is configured for transdermal glucose monitoring of a recipient. The system can include a sensor module housing, which can include a first flex arm, a sensor having a first section configured for subcutaneous sensing and a second section mechanically coupled to the sensor module housing, an electrical interconnect mechanically coupled to the sensor module housing and electrically coupled to the sensor, and / or a base coupled to the first flex arm of the sensor module housing. The base can have an adhesive configured to couple the base to the recipient's skin. The sensor can be an analyte sensor, a glucose sensor, any sensor described herein or incorporated by reference, and / or any other suitable sensor.

[0054] In some embodiments, the electrical interconnect comprises a spring. The spring can comprise a conical portion and / or a helical portion.

[0055] In some embodiments, the sensor module housing includes at least two proximal protrusions positioned around a circumference of the spring. The proximal protrusions can be configured to assist in orienting the spring. The segments of the sensor can be positioned between the proximal protrusions.

[0056] In some embodiments, the sensor module housing is mechanically coupled to a base having an adhesive configured to bond the base to the recipient's skin.

[0057] In some embodiments, the proximal protrusion orients the spring such that coupling the electronics unit to the base presses the spring against a first electrical contact on the electronics unit and a second electrical contact on the sensor, electrically coupling the sensor to the electronics unit.

[0058] In some embodiments, the sensor module housing includes a first flex arm oriented horizontally and coupled to a base. The first flex arm can extend from a perimeter of the sensor module housing. The base can include a first proximal protrusion coupled to the first flex arm to couple the sensor module housing to the base.

[0059] In some embodiments, the electrical interconnect comprises a leaf spring, which may include one metal layer or multiple metal layers. The leaf spring may be a cantilever spring.

[0060] In some embodiments, the sensor module housing includes a proximal protrusion having a channel in which at least a portion of the second section of the sensor is positioned. The channel can position the first region of the sensor such that the first region is electrically coupled to the leaf spring.

[0061] In some embodiments, the leaf spring arcs away from the first region and protrudes proximally to electrically couple with the electronics unit. At least a portion of the leaf spring can form a "W" shape. At least a portion of the leaf spring forms a "C" shape.

[0062] In some embodiments, the leaf spring bends around the proximal protrusion. The leaf spring can bend at least 120 degrees and / or at least 160 degrees around the proximal protrusion. The leaf spring protrudes proximally and electrically couples with the electronics unit.

[0063] In some embodiments, the seal is configured to prevent ingress of fluid to the leaf spring. The sensor module housing can be mechanically coupled to the base. The base can have an adhesive configured to couple the base to the recipient's skin.

[0064] In some embodiments, the proximal protrusion orients the spring such that coupling the electronics unit to the base presses the spring against a first electrical contact of the electronics unit and a second electrical contact of the sensor, electrically coupling the sensor to the electronics unit. A proximal height of the seal can be greater than a proximal height of the leaf spring such that the electronics unit contacts the seal before the seal contacts the leaf spring.

[0065] In some embodiments, the sensor module housing includes a first flex arm oriented horizontally and coupled to a base. The first flex arm can extend from a perimeter of the sensor module housing. The base can include a first proximal protrusion coupled to the first flex arm to couple the sensor module housing to the base.

[0066] In some embodiments, the sensor module housing includes a channel in which at least a portion of the second section of the sensor is positioned. A distal portion of the leaf spring can be positioned within the channel such that a proximal portion of the leaf spring protrudes proximally from the channel. The sensor module housing can include a groove that intersects the channel. The leaf spring can include a tab positioned within the groove to prevent rotation of the leaf spring.

[0067] In some embodiments, the sensor module housing is mechanically coupled to a base having an adhesive configured to couple the base to the skin of a recipient. The sensor module housing can include a first flex arm oriented horizontally and coupled to the base. The first flex arm can extend from a perimeter of the sensor module housing. The base can include a first proximal protrusion coupled to the first flex arm to couple the sensor module housing to the base.

[0068] In some embodiments, the electrical interconnects (such as springs or other types of interconnects) have a resistance of less than 100 ohms and / or less than 5 ohms. The electrical interconnects can have a compressive force of less than 1 pound over the active compression range.

[0069] In some embodiments, the electrical interconnect may require less than 1 pound of compression force to compress the spring 20 percent from the relaxed position, which is a substantially uncompressed position. In some embodiments, the electrical interconnect may require less than 1 pound of compression force to compress the spring 25 percent from the relaxed position, which is a substantially uncompressed position. In some embodiments, the electrical interconnect may require less than 1 pound of compression force to compress the spring 30 percent from the relaxed position, which is a substantially uncompressed position. In some embodiments, the electrical interconnect may require less than 1 pound of compression force to compress the spring 50 percent from the relaxed position, which is a substantially uncompressed position.

[0070] In some embodiments, the spring is configured such that compressing the spring 25 percent from the relaxed position requires a force of at least 0.05 pounds and less than 0.5 pounds, and requires the end of the spring to move at least 0.1 millimeters and less than 1.1 millimeters.

[0071] In some embodiments, a system for applying an on-skin sensor assembly to the skin of a recipient includes a nestable assembly having a first portion configured to move distally relative to a second portion along a path from a proximal start position to a distal position, a sensor coupled to the first portion, and a base comprising an adhesive configured to couple the sensor to the skin. The nestable assembly can further include a third portion configured to move distally relative to the second portion.

[0072] In some embodiments, the first spring is positioned between the third portion and the second portion such that moving the third portion distally relative to the second portion compresses the first spring. In a proximal start position of the nested assembly, the first portion can be locked to the second portion. The system can be configured such that moving the third portion distally relative to the second portion unlocks the first portion from the second portion.

[0073] In some embodiments, a first proximal projection having a first hook passes through a first hole in the second portion to lock the first portion to the second portion. The third portion can include a first distal projection. The system can be configured such that distal movement of the third portion relative to the second portion engages the ramp portion to bend the first proximal projection to unlock the first portion from the second portion.

[0074] In some embodiments, the sensor is positioned within the second portion while the base protrudes from the distal end of the system such that the system is configured to couple the sensor to the base via moving the first portion distally relative to the second portion.

[0075] In some embodiments, the sensor module is coupled to a distal portion of the first portion such that moving the first portion to a distal position couples the sensor module to the base. The sensor can be coupled to the sensor module while the first portion is positioned in a proximal start position.

[0076] In some embodiments, the system is configured such that moving the third portion distally relative to the second portion unlocks the first portion from the second portion and locks the third portion to the second portion.

[0077] In some embodiments, the system comprises a first protrusion that mates with at least one aperture of the second portion and the third portion to lock the third portion to the second portion.

[0078] In some embodiments, the system includes a second protrusion that engages with at least one aperture in the first portion and the second portion to lock the first portion to the second portion in response to the first portion moving distally relative to the second portion.

[0079] In some embodiments, the first spring is positioned between the third portion and the second portion such that moving the third portion distally relative to the second portion compresses the first spring and unlocks the first portion from the second portion, allowing the compressed first spring to press the first portion against the second portion, pushing at least a portion of the sensor out of the distal end of the system and triggering the needle retraction mechanism, allowing the second spring to retract the needle.

[0080] In some embodiments, a system is provided for applying an on-skin assembly to the skin of a recipient. Conveniently, the system includes a sensor inserter assembly having a needle assembly, a sensor module, a base, an actuation member, and a storage member, the sensor inserter assembly having an initial configuration in which at least the sensor module is disposed at a proximal start position, and the sensor inserter assembly further has a deployed configuration in which at least the sensor module and the base are disposed at a distal application position. Preferably, the actuation member is configured to, upon activation, move the needle assembly from the proximal start position to the distal insertion position, and the storage member is configured to, upon activation, move the needle assembly from the distal insertion position to the proximal storage position.

[0081] The sensor module may include a sensor and a number of electrical contacts. In the initial configuration, the sensor may be electrically coupled to at least one of the electrical contacts. Optionally, in the initial configuration, the actuating member is in a non-energized state. In some embodiments, the actuating member may be configured to be energized by a user before being activated. In an alternative embodiment, in the initial configuration, the actuating member is in an energized state.

[0082] In some embodiments, the actuation member may include a spring. In the initial configuration, the spring may be in an unstressed state. In an alternative embodiment, in the initial configuration, the spring is in a compressed state.

[0083] In some embodiments, the sensor inserter assembly can include a first portion and a second portion, the first portion being at least axially fixed relative to the second portion at least when the sensor inserter assembly is in an initial configuration, and the first portion being movable at least distally relative to the second portion after actuation of the actuation member. The first portion can be operably coupled to the needle assembly to fix the needle assembly in a proximal start position prior to actuation of the actuation member and to bias the needle assembly toward a distal insertion position after actuation of the actuation member.

[0084] In some embodiments, in the initial configuration, the storage member is in a non-energized state. Conveniently, the storage member is configured to be energized by movement of the needle assembly from a proximal start position to a distal insertion position. In the initial configuration, the storage member may be in an energized state.

[0085] In yet another embodiment, the storage member comprises a spring. The spring can be integrally formed with the needle assembly. The spring can operably couple the assembly to the needle. In the initial configuration, the spring can be in an unstressed state. In another embodiment, in the initial configuration, the spring is in a compressed state.

[0086] In some embodiments, in the second configuration, the spring is in a compressed state, hi yet other embodiments, in the second configuration, the spring is in a tensioned state.

[0087] In some embodiments, the sensor inserter assembly can further include a third portion, the third portion operably coupled to the first portion. In certain embodiments, the actuating member can be integrally formed with the third portion. Optionally, the actuating member is operably coupled to the third portion.

[0088] In some embodiments, the sensor inserter assembly includes an interengagement structure configured to prevent distal movement of the first portion relative to the second portion until the interengagement structure is decoupled. Conveniently, decoupling the interengagement structure can activate an actuation member. In other embodiments, the interengagement structure can comprise a proximally extending tab on the first portion and a receptacle on the second portion configured to receive the proximally extending tab. Optionally, the sensor inserter assembly can include a decoupling member configured to decouple the interengagement structures. The decoupling member can have a distally extending tab on the third portion.

[0089] In yet other embodiments, the sensor inserter assembly can include interengagement structures configured to prevent proximal movement of the third portion relative to the first portion. These interengagement structures can include a distally extending latch on the third portion and a ledge on the first portion configured to engage the distally extending latch.

[0090] In certain embodiments, the sensor inserter assembly may include an interengagement structure configured to prevent proximal movement of the needle assembly at least when the needle assembly is in the distal insertion position. The interengagement structure may have a radially extending release feature of the needle assembly and an inner surface of the first portion configured to compress the release feature. Optionally, the sensor inserter assembly includes a decoupling member configured to disengage the interengagement structure of the first portion from the needle assembly. The decoupling member may include an inner surface of the second portion configured to further compress the release feature. Conveniently, the system may further include a trigger member configured to activate the actuation member. The trigger member may be operably coupled to the third portion. The trigger member may be integrally formed with the third portion. The trigger member may include a proximally extending button. Alternatively, the trigger member may include a radially extending button. The trigger member may be configured to decouple the interengagement structures of the first portion and the third portion.

[0091] In some embodiments, the sensor may further include a releasable locking member configured to prevent activation of the actuation member until the locking member is released. The releasable locking member may be configured to prevent proximal movement of the third portion relative to the first portion until the locking member is released. The releasable locking member may include a proximally extending tab on the first portion and a latch feature on the third portion configured to receive the proximally extending tab. Advantageously, the releasable locking member is configured to prevent energization of the sensor inserter assembly. In other aspects, the releasable locking member is configured to prevent energization of the actuation member.

[0092] Embodiments may further include a system for applying the on-skin component to the skin of a recipient, the system comprising a sensor inserter assembly having an on-skin component movable in a distal direction from at least a proximal position to a distal position, a first fixation feature configured to releasably secure the on-skin component at the proximal position, a second fixation feature configured to secure the on-skin component at the distal position, and a first resistance configured to prevent proximal movement of the on-skin component at least when the on-skin component is in the distal position.

[0093] The first resistive feature can be configured to prevent proximal movement of the on-skin component when the on-skin component is secured in the distal position. In some embodiments, the first securing feature is configured to releasably secure the on-skin component to the needle assembly. The on-skin component can have a sensor module. The sensor module can include a sensor and a plurality of electrical contacts. Optionally, the sensor is electrically coupled to at least one of the electrical contacts at least when the sensor inserter assembly is in the first configuration.

[0094] In some embodiments, the on-skin component comprises a base. The on-skin component can include a transmitter. The second fastening feature can be configured to fasten the on-skin component to a second on-skin component.

[0095] In other embodiments, the sensor inserter assembly includes at least one distally extending leg, and the first securing feature comprises an adhesive disposed on a distally facing surface of the leg. The sensor inserter assembly can include at least one distally extending member, and the first securing feature comprises a surface of the distally extending member configured to frictionally engage a corresponding structure of the on-skin component. The corresponding structure of the on-skin component can include an elastomeric member. Optionally, the distally extending member includes at least one leg of the sensor inserter assembly. The distally extending member can include a needle.

[0096] In some embodiments, the second fixation feature comprises an adhesive disposed on a distal-facing surface of the on-skin component. The second fixation feature can have an elastomeric member configured to receive the on-skin component.

[0097] In other embodiments, the first resistive feature comprises a distal-facing surface of the sensor inserter assembly. The first resistive feature can be distal to an adhesive disposed on the distal-facing surface of the on-skin component.

[0098] The system may further include a pusher configured to move the on-skin component from a proximal position to a distal position. Optionally, the system may further include a decoupling feature configured to decouple the pusher from the on-skin component at least after the on-skin component is in the distal position. The decoupling feature may comprise a weakened portion of the pusher. Optionally, the decoupling feature comprises a weakened portion of the on-skin component.

[0099] The system may further include a sensor assembly configured to couple with the on-skin component, wherein the third fixation feature is configured to releasably secure the sensor assembly in a proximal position and the fourth fixation feature is configured to secure the sensor assembly to the on-skin component.

[0100] Any of the features of an aspect shown herein is applicable to all other aspects and embodiments specified herein. Furthermore, any of the features of one embodiment may be combined, partially or wholly, independently with other embodiments described herein, for example, one, two, or more than two embodiments may be combined in whole or in part. Furthermore, any of the features of one embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0101] These and other features, aspects, and advantages are described below with reference to the drawings, which are intended to illustrate, but not limit, the invention, in which like reference characters indicate corresponding features consistently throughout similar embodiments. [Brief description of the drawings]

[0102] [Figure 1] 1 is a schematic diagram of a continuous analyte sensor system, according to some embodiments. [Diagram 2] FIG. 1 illustrates a perspective view of an applicator system, according to some embodiments. [Diagram 3] 3 is a cross-sectional side view of the system from FIG. 2 according to some embodiments. [Figure 4] FIG. 1 illustrates a perspective view of an on-skin sensor assembly according to some embodiments. [Diagram 5] FIG. 1 illustrates a perspective view of a transmitter coupled to a base via a mechanical interlock in accordance with some embodiments. [Figure 6] FIG. 1 illustrates a perspective view of a transmitter coupled to a base via a mechanical interlock in accordance with some embodiments. [Figure 7] 4 is a side cross-sectional view of the applicator system from FIG. 3 according to some embodiments. [Figure 8] 4 is a side cross-sectional view of the applicator system from FIG. 3 according to some embodiments. [Figure 9] 4 is a side cross-sectional view of the applicator system from FIG. 3 according to some embodiments. [Figure 10] 4 is a side cross-sectional view of the applicator system from FIG. 3 according to some embodiments. [Figure 11] 4 is a side cross-sectional view of the applicator system from FIG. 3 according to some embodiments. [Figure 12A] 4 is a side cross-sectional view of a portion of the applicator system from FIG. 3 according to some embodiments. [Figure 12B]4 is a side cross-sectional view of a base that can be used with the applicator system shown in FIG. 3 according to some embodiments. [Figure 13] 5 is a perspective view of a portion of the adhesive from FIG. 4 according to some embodiments. [Figure 14] 4 is a perspective view of a portion of the applicator system from FIG. 3 according to some embodiments. [Figure 15] 8 is a cross-sectional perspective view of a portion of the system shown in FIG. 7 according to some embodiments. [Figure 16] 8 is a cross-sectional perspective view of a portion of the system shown in FIG. 7 according to some embodiments. [Figure 17] 8 is a cross-sectional view of a first portion of the nestable assembly from FIG. 7 according to some embodiments. [Figure 18] 8 is a perspective view of a portion of the applicator system from FIG. 7 according to some embodiments. [Figure 19] 8 is a perspective view of a portion of the applicator system from FIG. 7 according to some embodiments. [Figure 20] 8 is a perspective view of a needle after being removed from the nesting assembly of FIG. 7 according to some embodiments. [Figure 21] 8 is a perspective view of a needle after being removed from the nesting assembly of FIG. 7 according to some embodiments. [Figure 22] FIG. 8 is a perspective view of a cover of the nestable assembly of FIG. 7 according to some embodiments. [Diagram 23] 1 is a schematic diagram of a force profile according to some embodiments. [Figure 24] 1 is a side cross-sectional view of a portion of an applicator system, according to some embodiments. [Diagram 25] 13A-13C are side cross-sectional views of a portion of a securing mechanism according to some embodiments. [Figure 26] FIG. 13 is a top view of a ring, according to some embodiments. [Figure 27] 1 is a perspective view of a securing mechanism according to some embodiments. [Figure 28] FIG. 13 is a cross-sectional perspective view of a telescoping assembly having a motor according to some embodiments. [Figure 29] FIG. 13 is a cross-sectional side view of a telescoping assembly having a motor, according to some embodiments. [Diagram 30] FIG. 13 is a cross-sectional side view of a telescoping assembly having a motor, according to some embodiments. [Diagram 31] FIG. 13 is a side view of a telescoping assembly that produces rotational movement, according to some embodiments. [Diagram 32] FIG. 13 is a cross-sectional perspective view of a nested assembly having a downward locking feature according to some embodiments. [Diagram 33] FIG. 13 is a perspective view of an on-skin senor assembly just before the electronics unit is coupled to the base, according to some embodiments. [Diagram 34] 1 illustrates a perspective view of a sensor module having a spring according to some embodiments. [Diagram 35] 1 illustrates a perspective view of a sensor module having a spring according to some embodiments. [Diagram 36] FIG. 2 is a cross-sectional perspective view of a portion of a sensor module according to some embodiments. [Figure 37] 1 illustrates a perspective view of a sensor module having a spring according to some embodiments. [Figure 38] FIG. 2 is a cross-sectional perspective view of a portion of a sensor module according to some embodiments. [Figure 39] FIG. 1 illustrates a perspective view of a sensor module according to some embodiments. [Diagram 40] FIG. 13 is a cross-sectional perspective view of an assembly having an offset according to some embodiments. [Diagram 41] FIG. 2 is a side view of a sensor according to some embodiments. [Diagram 42] FIG. 13 is a bottom view of a needle, according to some embodiments. [Diagram 43] FIG. 1 is a front view of a needle according to some embodiments. [Diagram 44]1 is a cross-sectional perspective view of an applicator system according to some embodiments. FIG. [Diagram 45] 1 is a cross-sectional perspective view of a portion of an applicator system according to some embodiments. [Figure 46] FIG. 1 is a perspective view of a portion of an applicator system, according to some embodiments. [Figure 47] FIG. 1 illustrates a perspective view of a sensor module according to some embodiments. [Figure 48] 1 is a cross-sectional perspective view of an applicator system according to some embodiments. FIG. [Figure 49] FIG. 13 is a cross-sectional perspective view of a proximal portion of a nestable assembly according to some embodiments. [Figure 50] 13A-13C are perspective views of a distal portion of a nestable assembly according to some embodiments. [Figure 51] FIG. 13 is a perspective view of a needle with an adhesive according to some embodiments. [Figure 52] FIG. 1 illustrates a perspective view of a needle having two separate sides, according to some embodiments. [Figure 53] FIG. 53 is a cross-sectional top view of the needle shown in FIG. 52 according to some embodiments. [Figure 54] FIG. 13 is a perspective view of a needle having a ramp, according to some embodiments. [Figure 55] FIG. 13 is a cross-sectional top view of four needles, according to some embodiments. [Figure 56] 8 is a side cross-sectional view of a system similar to the embodiment shown in FIG. 7 except that the system does not include a needle, according to some embodiments. [Figure 57] 8 is a side cross-sectional view of a system similar to the embodiment shown in FIG. 7 except that the system does not include a needle, according to some embodiments. [Figure 58] 8 is a side cross-sectional view of a system similar to the embodiment shown in FIG. 7 except that the system does not include a needle, according to some embodiments. [Figure 59]8 is a side cross-sectional view of a system similar to the embodiment shown in FIG. 7 except for the starting position and movement of the base, according to some embodiments. [Figure 60] FIG. 1 illustrates a perspective view of a system having a cover, according to some embodiments. [Figure 61] FIG. 8 is a cross-sectional perspective view of a system similar to the embodiment shown in FIG. 7 except that the nesting assembly includes an additional portion. [Figure 62] FIG. 8 is a cross-sectional perspective view of a system similar to the embodiment shown in FIG. 7 except that the nesting assembly includes an additional portion. [Figure 63] FIG. 8 is a cross-sectional perspective view of a system similar to the embodiment shown in FIG. 7 except that the nesting assembly includes an additional portion. [Figure 64] FIG. 64 is a side cross-sectional view of the system shown in FIGS. 61-63 according to some embodiments. [Figure 65] 1 is a perspective view of a portion of a sensor module according to some embodiments. [Figure 66] FIG. 66 is a side cross-sectional view of the sensor module shown in FIG. 65 according to some embodiments. [Figure 67] 1 is a perspective view of a portion of a sensor module according to some embodiments. [Figure 68] FIG. 68 is a top view of the sensor module shown in FIG. 67 according to some embodiments. [Figure 69] 1 is a perspective view of an electronics unit just before the electronics unit is coupled to a base according to some embodiments. FIG. [Figure 70] 1 is a perspective view of an electronics unit just before the electronics unit is coupled to a base according to some embodiments. FIG. [Figure 71] 1A-1C are cross-sectional perspective views of an applicator system in a resting state, according to some embodiments. [Figure 72] 72 is a cross-sectional perspective view of the applicator system of FIG. 71 with the actuation member energized. FIG. [Figure 73] FIG. 73 is a rotated cross-sectional perspective view of the applicator system of FIG. 72. [Figure 74] 72 is a cross-sectional perspective view of the applicator system of FIG. 71 with the actuation member activated to deploy the needle assembly into an insertion position. [Figure 75] FIG. 72 is a cross-sectional perspective view of the applicator system of FIG. 71 with the on-skin component in a deployed position and the needle assembly retracted. [Figure 76] 1 is a cross-sectional side view of another applicator system in a stationary state, according to some embodiments. [Figure 77] 77 is a side cross-sectional view of the applicator system of FIG. 76 with the actuation member energized. [Figure 78] 77 is a side cross-sectional view of the applicator system of FIG. 76 with the actuation member activated to deploy the needle assembly into an insertion position. [Figure 79] 77 is a side cross-sectional view of the applicator system of FIG. 76 with the on-skin component in a deployed position and the needle assembly retracted. [Figure 80] 1 is a side cross-sectional view of another applicator system in a stationary state, according to some embodiments. [Figure 81] 81 is a side cross-sectional view of the applicator system of FIG. 80 with the actuation member energized. [Figure 82] 81 is a side cross-sectional view of the applicator system of FIG. 80 with the actuation member activated to deploy the needle assembly into an insertion position. [Figure 83] 81 is a side cross-sectional view of the applicator system of FIG. 80 with the on-skin component in a deployed position and the needle assembly retracted. [Figure 84] 81 is a perspective view of the applicator system of FIG. 80 in a stationary state, with the first and third portions shown in cross-section to better illustrate certain parts of the system. [Figure 85] 81 is a perspective view of the applicator system of FIG. 80 with the first and third portions shown in cross-section to better illustrate certain parts of the system and with the actuating member energized. [Figure 86]13 is a cross-sectional side view of another applicator system in a quiescent state with the actuation member already energized, according to some embodiments. [Figure 87] 87 is a side cross-sectional view of the applicator system of FIG. 86 with the actuation member activated to deploy the needle assembly into an insertion position. [Figure 88] 87 is a side cross-sectional view of the applicator system of FIG. 86 with the on-skin component in the deployed position and the needle assembly retracted. [Figure 89] 13 is a cross-sectional side view of another applicator system in a quiescent state with the actuation member already energized, according to some embodiments. [Figure 90] 87 is a side cross-sectional view of the applicator system of FIG. 86 with the actuation member activated to deploy the needle assembly into an insertion position. [Figure 91] 87 is a side cross-sectional view of the applicator system of FIG. 86 with the on-skin component in the deployed position and the needle assembly retracted. [Figure 92] FIG. 13 is a side view of another applicator system in a stationary state having a top trigger member in accordance with some embodiments. [Figure 93] FIG. 93 is a side view of the applicator system of FIG. 92 after it has been cocked but before it has been triggered. [Figure 94] 93 is a cross-sectional perspective view of the applicator system of FIG. 92 in a stationary state. [Figure 95] FIG. 93 is a cross-sectional perspective view of the applicator system of FIG. 92 while cocked. [Figure 96] 93 is a cross-sectional perspective view of the applicator system of FIG. 92 after it has been cocked but before it has been triggered. [Figure 97] FIG. 97 is a side cross-sectional view of the applicator system of FIG. 96. [Figure 98] FIG. 93 is a side cross-sectional view of the applicator system of FIG. 92 during triggering. [Figure 99] 93 is a side cross-sectional view of the applicator system of FIG. 92 after being triggered and with the needle assembly deployed in an insertion position. [Figure 100] 93 is a side cross-sectional view of the applicator system of FIG. 92 with the on-skin component in a deployed position and the needle assembly retracted. [Figure 101] 13 is a side view of another applicator system having a side trigger member, according to some embodiments. [Figure 102] 102 is another side view of the applicator system of FIG. 101 with the first and third portions shown in cross-section to illustrate the trigger mechanism. [Figure 103] FIG. 13 is a side view of another applicator system having an integrated side trigger, according to some embodiments. [Figure 104] 104 is another side view of the applicator system of FIG. 103 with the first and third portions shown in cross-section and a portion of the second portion removed to illustrate the trigger mechanism. [Figure 105] FIG. 13 is a perspective view of another applicator system having a safety feature, according to some embodiments. [Fig. 106] 106 is a cross-sectional perspective view of a portion of the applicator system of FIG. 105, with the safety feature in a locked configuration. [Figure 107] FIG. 107 is an enlarged view of a portion of the applicator system of FIG. 106, with the safety feature in a locked configuration. [Figure 108] 106 is a cross-sectional perspective view of a portion of the applicator system of FIG. 105, with the safety feature in an unlocked configuration. [Fig. 109] 106 is a cross-sectional perspective view of a portion of the applicator system of FIG. 105 with the safety feature in an unlocked configuration and the third portion moved distally relative to the first portion. [Figure 110] 1A-1C are cross-sectional perspective views of the applicator system in a resting and locked state with the on-skin component fixed in a proximal position, according to some embodiments. [Figure 111] FIG. 111 is a cross-sectional perspective view of the applicator system of FIG. 110 with the safety feature unlocked. [Figure 112]FIG. 111 is a cross-sectional perspective view of the applicator system of FIG. 110 with the actuating member energized. [Figure 113] FIG. 111 is a cross-sectional perspective view of the applicator system of FIG. 110 with the actuating member activated to deploy the needle assembly and on-skin component to a distal position. [Fig. 114] 111 is a cross-sectional perspective view of the applicator system of FIG. 110 with the on-skin component in a deployed position and separated from the retracted needle assembly. [Fig. 115] FIG. 111 is a perspective view of a needle assembly from the system of FIG. 110 showing fixation of the on-skin component during deployment, with the base removed for purposes of illustration. [Fig. 116] FIG. 111 is a perspective view of another needle assembly from the system of FIG. 110 showing separation from the on-skin component, with the base removed for purposes of illustration. [Fig. 117] FIG. 101 is a perspective view of a portion of the system of FIG. [Fig. 118] FIG. 101 is a perspective view of the sensor module of FIG. 100 prior to being coupled to a base. [Figure 119] FIG. 101 is a perspective view of the sensor module of FIG. 100 after being coupled to a base. [Figure 120] FIG. 13 is a side view of an on-skin component and a base prior to coupling of the on-skin component to the base, according to some embodiments. [Figure 121] FIG. 121 is a perspective view of the on-skin component and base of FIG. 120 prior to bonding of the on-skin component to the base. [Figure 122] FIG. 121 is a side view of the on-skin component and base of FIG. 120 after bonding of the on-skin component to the base. [Figure 123] FIG. 13 is a perspective view of a portion of another applicator system with an on-skin component coupled to a needle assembly in a proximal position, in accordance with some embodiments. [Figure 124] FIG. 124 is a perspective view of the on-skin component and needle assembly of FIG. 123. [Fig. 125] FIG. 124 is a perspective view of a portion of the applicator system shown in FIG. 123 with the on-skin components separated from the needle assembly. [Fig. 126] FIG. 13 is a perspective view of a portion of a fixation member showing fixation of the on-skin components. [Figure 127] FIG. 127 is a perspective view of a portion of the fixation member of FIG. 126 showing the sensor module of the on-skin component in cross-section and illustrated with decoupling features of the applicator assembly according to some embodiments. [Figure 128] 127 is a perspective view of the on-skin component of FIG. 126 after the on-skin component has been decoupled from the fixation member. FIG. [Figure 129] 13 is a perspective view of a portion of the applicator assembly showing a second portion in cross-section and illustrating fixation of the on-skin component at a proximal position by a fixation member, according to some embodiments. [Fig. 130] FIG. 130 is a perspective view of a portion of the applicator assembly of FIG. 129 with a portion of the fixation member cut away to better illustrate the configuration of the fixation member. [Fig. 131] FIG. 130 is a perspective view of a portion of the applicator assembly of FIG. 129 after decoupling the on-skin component from the needle assembly, showing a portion of the on-skin component and the fixation member cut away. [Fig. 132] 13 is a perspective view of a portion of the applicator assembly showing a second portion in cross-section and illustrating fixation of the on-skin component at a proximal position by a fixation member, according to some embodiments. [Fig. 133] FIG. 133 is a perspective view of the needle assembly and on-skin component of FIG. 132 after the on-skin component has been decoupled from the needle assembly. [Fig. 134] FIG. 13 is an exploded perspective view of a portion of the applicator assembly, with a securing member configured to releasably couple the on-skin component to the needle assembly, according to some embodiments. [Fig. 135] FIG. 135 is a perspective view of a portion of the applicator assembly of FIG. 134 with the needle assembly coupled to the on-skin component. [Fig. 136] FIG. 135 is a perspective view of a portion of the applicator assembly of FIG. 134 with the needle assembly decoupled from the on-skin component. [Fig. 137] FIG. 2 is a perspective view of an applicator assembly with an on-skin component releasably secured at a proximal position within the applicator assembly, in accordance with some embodiments; [Figure 138] FIG. 138 is a perspective view of the applicator assembly of FIG. 137 with the on-skin component released from fixation. [Figure 139] FIG. 138 is a perspective view of the on-skin component of FIG. 137 with the fixation feature in a fixed configuration. [Fig. 140] FIG. 138 is a perspective view of the on-skin component of FIG. 137 with the fixation feature in a released configuration. [Fig. 141] 1 is a cross-sectional perspective view of a portion of an applicator assembly, with the second and third portions shown in cross-section and the base shown coupled to the applicator, according to some embodiments. [Fig. 142] 1 is a perspective view of another applicator assembly, showing a patch coupled to the applicator, in accordance with some embodiments. [Fig. 143] 143 is a perspective view of the applicator assembly of FIG. 142 with the patch decoupled from the applicator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0103] Although specific embodiments and examples are disclosed below, the subject matter of the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and / or uses, as well as modifications and equivalents thereof. Thus, the scope of the claims appended hereto is not limited by any of the specific embodiments described below. For example, in any method or process disclosed herein, the activities or operations of the method or process can be performed in any suitable sequence and are not necessarily limited to any particular sequence disclosed. Although various operations may be described one by one as multiple separate operations in a manner that may be helpful in understanding a particular embodiment, the order of description should not be construed to imply that these operations are order dependent. In addition, the structures, systems, and / or devices described herein can be embodied as integral components or as separate components.

[0104] For purposes of comparing various embodiments, certain aspects and advantages of those embodiments are described. Not necessarily all such aspects or advantages are achieved by any particular embodiment. Thus, for example, various embodiments may be implemented in a manner that achieves or optimizes one advantage or group of advantages taught herein, but not necessarily achieves other aspects or advantages that may be taught or suggested herein.

[0105] System Introduction US Patent Application Publication No. US2013 / 0267811(A1), the entire contents of which are incorporated herein by reference, is a schematic diagram illustrating how a continuous analyte sensor system 100 may be attached to a recipient (e.g., a person). The analyte sensor system 100 communicates with other devices 110-113 (which may be located remotely from the recipient). A transdermal analyte sensor system 102 comprising an on-skin sensor assembly 600 is affixed to the skin of the recipient via a base (not shown), which may be a disposable housing.

[0106] The system includes a transdermal analyte sensor 200 and an electronics unit (interchangeably referred to as "sensor electronics" or "transmitter") 500 for wirelessly transmitting analyte information. The receiver can be located remotely relative to the system 102. In some embodiments, the receiver includes a display screen that can display information to a person, such as a recipient. Exemplary receivers include computers, such as smartphones, smart watches, tablet computers, laptop computers, and desktop computers. In some embodiments, the receiver can be an Apple Watch®, iPhone®, and iPad® manufactured by Apple Inc. In further embodiments, the system 102 can be configured for use in applying a drug delivery device, such as an infusion device, to the patient's skin. In such embodiments, the system can include a catheter instead of or in addition to the sensor, the catheter being connected to an infusion pump configured to deliver a liquid medication or other fluid. In embodiments, the catheter can be deployed into the skin in much the same manner as a sensor is deployed, for example, as described herein.

[0107] In some embodiments, the receiver is mechanically coupled to the electronics unit 500, allowing the receiver to receive data (e.g., analyte data) from the electronics unit 500. For increased user convenience, in some embodiments, the receiver does not need to be mechanically coupled to the electronics unit 500, yet can receive data from the electronics unit 500 over long distances (e.g., when the receiver is several feet or even miles from the electronics unit 500).

[0108] During use, a sensing portion of the sensor 200 can be placed under the skin of a recipient, and a contact portion of the sensor 200 can be electrically connected to the electronics unit 500. The electronics unit 500 can be engaged with a housing attached to an adhesive patch that is adhered to the skin of the recipient.

[0109] The on-skin assembly 600 can be attached to a recipient using an applicator adapted to provide convenient and safe application. Such an applicator can also be used to attach the electronics unit 500 to a base, to insert the sensor 200 through the recipient's skin, and / or to connect the sensor 200 to the electronics unit 500. Once the electronics unit 500 is engaged with the base and the sensor 200 is inserted into the skin (and connected to the electronics unit 500), the sensor assembly can be removed from the applicator.

[0110] The continuous analyte sensor system 100 can include a sensor arrangement that provides an output signal indicative of an analyte concentration. The output signal (including sensor data, such as raw data, filtered data, smoothed data, and / or otherwise transformed data, for example) is transmitted to a receiver.

[0111] In some embodiments, the analyte sensor system 100 includes a transcutaneous glucose sensor as described in U.S. Patent Application Publication No. US2011 / 0027127(A1), the contents of which are incorporated herein by reference in their entirety. In some embodiments, the sensor system 100 includes a continuous glucose sensor (e.g., as described in U.S. Patent No. 6,565,509, as described in U.S. Patent No. 6,579,690, as described in U.S. Patent No. 6,484,046), the contents of which include a transcutaneous sensor are incorporated herein by reference in their entirety.

[0112] In some embodiments, sensor system 100 includes a continuous glucose sensor (e.g., as described in U.S. Pat. No. 6,512,939) and includes a replaceable subcutaneous sensor. In some embodiments, sensor system 100 includes a continuous glucose sensor (e.g., as described in U.S. Pat. No. 6,477,395, as described in U.S. Pat. No. 6,424,847) and includes an intravascular sensor. The contents of U.S. Pat. Nos. 6,512,939, 6,477,395, and 6,424,847 are incorporated herein by reference in their entireties.

[0113] Various signal processing techniques and glucose monitoring system embodiments suitable for use with the embodiments described herein are described in U.S. Patent Application Publication Nos. US2005 / 0203360(A1) and US2009 / 0192745(A1), the contents of which are incorporated herein by reference in their entireties. The sensor may extend through a housing that may maintain the sensor on the skin and provide an electrical connection for the sensor to sensor electronics, which may be provided in electronics unit 500.

[0114] In some embodiments, the sensor is formed from or in the form of a wire. The distal end of the wire can be sharpened to form a cone shape (to facilitate insertion of the wire into the recipient's tissue). The sensor can include an elongated conductor, such as an exposed elongated conductive core (e.g., metal wire) or an elongated conductive core coated with one, two, three, four, five or more layers of metal, each of which may or may not be conductive. The elongated sensor can be long and thin, yet flexible and strong. For example, in some embodiments, the smallest dimension of the elongated conductor is less than 0.1 inches, less than 0.075 inches, less than 0.05 inches, less than 0.025 inches, less than 0.01 inches, less than 0.004 inches, and / or less than 0.002 inches.

[0115] The sensor may have a circular cross section. In some embodiments, the cross section of the elongated conductor may be ovoid, rectangular, triangular, polygonal, star-shaped, C-shaped, T-shaped, X-shaped, Y-shaped, irregular, or the like. In some embodiments, a conductive wire electrode is used as the core. Such electrodes may be supplemented with one or two additional conductive layers (e.g., with an intervening insulating layer provided for electrical insulation). The conductive layers may be composed of any suitable material. In certain embodiments, it may be desirable to use a conductive layer that includes conductive particles (i.e., particles of a conductive material) in a polymer or other binder.

[0116] In some embodiments, the materials used to form the elongated conductors (e.g., stainless steel, titanium, tantalum, platinum, platinum-iridium, iridium, certain polymers, and / or the like) can be strong and rigid, and therefore resistant to breakage. For example, in some embodiments, the ultimate tensile strength of the elongated conductors is greater than 80 kPsi and less than 500 kPsi, and / or the Young's modulus of the elongated conductors is greater than 160 GPa and less than 220 GPa. The yield strength of the elongated conductors can be greater than 60 kPsi and less than 2200 kPsi.

[0117] The electronics unit 500 can be releasably coupled to the sensor 200. The electronics unit 500 can include electronic circuitry associated with measuring and processing continuous analyte sensor data. The electronics unit 500 can be configured to perform algorithms associated with processing and calibrating sensor data. For example, the electronics unit 500 can provide various aspects of the functionality of a sensor electronics module as described in U.S. Patent Application Publication Nos. US2009 / 0240120(A1) and US2012 / 0078071(A1), the contents of which are incorporated herein by reference in their entireties. The electronics unit 500 can include hardware, firmware, and / or software that enables measurement of an analyte level via a glucose sensor, such as the analyte sensor 200.

[0118] For example, the electronics unit 500 can include a potentiostat, a power supply for powering the sensor 200, signal processing components, data storage components, and a communication module (e.g., a telemetry module) for one-way or two-way data communication between the electronics unit 500 and one or more receivers, repeaters, and / or display devices, such as devices 110-113. The electronics can be affixed to a printed circuit board (PCB) or the like and can take a variety of forms. For example, the electronics can take the form of an integrated circuit (IC), such as an application specific integrated circuit (ASIC), a microcontroller, and / or a processor. The electronics unit 500 can include sensor electronics configured to process sensor information, such as storing data, analyzing data streams, calibrating analyte sensor data, estimating analyte values, comparing estimated analyte values ​​to measured analyte values ​​over time, analyzing variations in estimated analyte values, and the like. Examples of systems and methods for processing sensor analyte data are described in U.S. Pat. No. 7,310,544, U.S. Pat. No. 6,931,327, U.S. Patent Application Publication No. 2005 / 0043598(A1), U.S. Patent Application Publication No. 2007 / 0032706(A1), U.S. Patent Application Publication No. 2007 / 0016381(A1), U.S. Patent Application Publication No. 2008 / 0033254(A1), U.S. Patent Application Publication No. 2005 / 02030302(A1), and U.S. Patent Application Publication No. 2005 / 02030302(A1). No. 03360(A1), U.S. Patent Application Publication No. 2005 / 0154271(A1), U.S. Patent Application Publication No. 2005 / 0192557(A1), U.S. Patent Application Publication No. 2006 / 0222566(A1), U.S. Patent Application Publication No. 2007 / 0203966(A1), and U.S. Patent Application Publication No. 2007 / 0208245(A1), the contents of which are incorporated herein by reference in their entireties.

[0119] One or more repeaters, receivers, and / or display devices, such as a key fob repeater 110, a medical device receiver 111 (e.g., an insulin delivery device and / or a dedicated glucose sensor receiver), a smartphone 112, a portable computer 113, and the like, can be communicatively coupled to the electronics unit 500 (e.g., to receive data from the electronics unit 500). The electronics unit 500 can also be referred to as a transmitter. In some embodiments, the devices 110-113 transmit data to the electronics unit 500. The sensor data can be transmitted from the sensor electronics unit 500 to one or more of the key fob repeater 110, the medical device receiver 111, the smartphone 112, the portable computer 113, and the like. In some embodiments, the analyte value is displayed on a display device.

[0120] The electronics unit 500 may communicate with the devices 110-113 and / or any number of additional devices via any suitable communication protocol, including radio frequency, Bluetooth, Universal Serial Bus, wireless local area network (WLAN) communication standards including IEEE 802.11, 802.15, 802.20, 802.22, and other 802 communication protocols, ZigBee, wireless (e.g., cellular) telecommunications, paging network communications, magnetic induction, satellite data communications, and / or proprietary communications protocols.

[0121] Additional sensor information is described in U.S. Patent Nos. 7,497,827 and 8,828,201, the entire contents of which are incorporated herein by reference.

[0122] Any sensor shown or described herein can be an analyte sensor, a glucose sensor, and / or any other suitable sensor. A sensor described in the context of any embodiment can be any sensor described herein or incorporated by reference. Thus, for example, the sensor 138 shown in FIG. 7 can be an analyte sensor, a glucose sensor, any sensor described herein, and any sensor incorporated by reference. A sensor shown or described herein can be configured to sense, measure, detect, and / or interact with any analyte.

[0123] As used herein, the term "analyte" is a broad term given its ordinary and customary meaning to those of skill in the art (and is not limited to any special or customized meaning), and further refers to, but is not limited to, a substance or chemical constituent in a biological fluid that can be analyzed (e.g., blood, interstitial fluid, cerebrospinal fluid, lymphatic fluid, urine, sweat, saliva, etc.). Analytes can include naturally occurring substances, man-made substances, metabolic substances, or reaction products.

[0124] In some embodiments, the analyte for measurement by the sensing region, device, system, and method is glucose. However, other analytes are contemplated as well, including ketone bodies, acetyl CoA, acarboxyprothrombin, acylcarnitine, adenine phosphoribosyltransferase, adenosine deaminase, albumin, alpha-fetoprotein, amino acid profile (arginine (Krebs cycle), histidine / urocanic acid, homocysteine, phenylalanine / tyrosine, tryptophan), andrenostenedione, antipyrine, arabinitol enantiomers, arginase, benzoylecgonine (cocaine), andrenostenedione, ... ), biotinidase, biopterin, c-reactive protein, carnitine, carnosinase, CD4, ceruloplasmin, chenodeoxycholic acid, chloroquine, cholesterol, cholinesterase, cortisol, testosterone, choline, creatine kinase, creatine kinase MM isoenzyme, cyclosporin A, d-penicillamine, de-ethylchloroquine, dehydroepiandrosterone sulfate, DNA (acetylation polymorphism, alcohol dehydrogenase, α1-antitrypsin, cystic fibrosis, Duchenne / Becker muscular dystrophy, analyte-6-phosphate dehydrogenase, hemoglobin A, hemoglobin S, hemoglobin C, hemoglobin D, hemoglobin E, hemoglobin F, D Punjab, beta-thalassemia, hepatitis B virus, HCMV, HIV-1, HTLV-1, Leber's hereditary optic neuropathy, MCAD, RNA, PKU, Plasmodium vivax, sex differentiation, 21-deoxycortisol), desbutylhalofantrine, dihydropteridine reductase, diphtheria / tetanus antitoxin, erythrocyte arginase, erythrocyte protoportholog phyrin, esterase D, fatty acids / acylglycines, triglycerides, glycerol, free beta-human chorionic gonadotropin, free erythrocyte porphyrins, free thyroxine (FT4), free tri-iodothyronine (FT3), fumarylacetoacetase, galactose / gal-1-phosphate, galactose-1-phosphate uridyltransferase, gentamicin, analyte-6-phosphate dehydrogenase, glutathione, glutathione peroxidase, glycocholate, glycosylated hemoglobin, halofantrine,Hemoglobin variants, hexosaminidase A, human erythrocyte carbonic anhydrase I, 17-α-hydroxyprogesterone, hypoxanthine phosphoribosyltransferase, immunoreactive trypsin, lactate, lead, lipoproteins ((a), B / A-1, β), lysozyme, mefloquine, netilmicin, phenobarbitone, phenytoin, phytanic acid / pristanic acid, progesterone, prolactin, prolidase, purine nucleoside phosphorylase, quinine, tri-iodothyronine (rT3), selenium, serum pancreatic lipase, sisomicin, somatomedin C, specific antibodies (adenovirus, antinuclear antibodies, anti-zeta antibodies, arbovirus, Aujeszky's disease virus, dengue virus, Dracaena fasciata, Echinococcus granulosus, Entamoeba histolytica, enterovirus, Giardia lamblia (giardia duodenalisa, Helicobacter pylori, Hepatitis B virus, Herpes virus, HIV-1, IgE (atopic disease), Influenza virus, Leishmania donovani, Leptospira, Measles / Mumps / Rubella, Mycobacterium leprae, Mycoplasma pneumoniae, Myoglobin, Onchocerca volvulus, Parainfluenza virus, Plasmodium falciparum, Poliovirus, Pseudomonas aeruginosa, Respiratory syncytial virus, Rickettsia (scrub typhus), Schistosoma mansoni, Toxoplasma gondii, Trepenoma pallidium, Trypanosoma cruzi / Langer, Vesicular stomatitis virus virus), Wuchereria bancrofti, Yellow Fever virus), specific antigens (Hepatitis B virus, HIV-1), acetone (e.g., succinylacetone), acetoacetate, sulfadoxine, theophylline, thyrotropin (TSH), thyroxine (T4), thyroxine-binding globulin, trace elements, transferrin, UDP-galactose-4-epimerase, urea, uroporphyrinogen I synthase, vitamin A, leukocytes, and zinc protoporphyrin.

[0125] Salts, sugars, proteins, lipids, vitamins, and hormones naturally occurring in blood or intestinal fluids may also constitute analytes in certain embodiments. Analytes may be naturally occurring in biological fluids or may be endogenous, such as metabolites, hormones, antigens, antibodies, etc. Alternatively, analytes may be introduced into the body or may be exogenous, such as contrast agents for imaging, radioisotopes, chemical agents, fluorocarbon-based synthetic blood, or drugs or pharmaceutical compositions, such as insulin, glucagon, ethanol, cannabis (marijuana, tetrahydrocannabinol, hashish), inhalants (nitrous oxide, amyl nitrite, butyl nitrite, chlorinated hydrocarbons, hydrocarbons), cocaine (crack cocaine), stimulants (amphetamines, methamphetamines, Ritalin, Cylert, Preludin, Didrex, PreState, Voranil, Sandrex, Plegine), depressants (barbiturates, methamphetamines ... Examples of drugs that may be used include, but are not limited to, tranquilizers such as tactrone, Valium, Librium, Miltown, Serax, Equanil, Tranxene, etc.), hallucinogens (phencyclidine, lysergic acid, mescaline, peyote, psilocybin), narcotics (heroin, codeine, morphine, opium, meperidine, Percocet, Percodan, Tussionex, Fentanyl, Darvon, Talwin, Lomotil), designer drugs (fentanyl, meperidine, amphetamine, methamphetamine, and analogs of phencyclidine, e.g., Ecstasy), anabolic steroids, and nicotine. Metabolites of drugs and pharmaceutical compositions are also contemplated analytes. Analytes such as neurochemicals and other chemicals produced in the body, such as ascorbic acid, uric acid, dopamine, noradrenaline, 3-methoxytyramine (3MT), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxytryptamine (5HT), and 5-hydroxyindoleacetic acid (FHIAA), can also be analyzed.

[0126] Many embodiments described herein use an adhesive (e.g., adhesive 126 in FIG. 7). One purpose of the adhesive is to allow the base, sensor module, and / or sensor to be attached to the recipient (e.g., to the recipient's skin). The adhesive can be configured to adhere to the skin. The adhesive can include a pad (e.g., positioned between the adhesive and the base). Additional adhesive information, including adhesive pad information, is described in U.S. Patent Application No. 14 / 835,603, filed August 25, 2015. The entire contents of U.S. Patent Application No. 14 / 835,603 are incorporated herein by reference.

[0127] Distal base location As discussed above, the system can apply an on-skin sensor assembly to the recipient's skin. The system can include a base with an adhesive that bonds the glucose sensor to the skin.

[0128] In some applicators, the base is hidden deep within the applicator until the user moves the needle distally with the base. One challenge with this approach is that the insertion site (on the recipient's skin) is not ideally prepared for sensor and / or needle insertion. For example, the distal end of the applicator may be a ring that presses against the skin. The pressure of the applicator against the skin may cause the area of ​​skin within the ring to form a convex shape. In addition, the skin within the ring may be easily compressed too much, thus lacking sufficient elasticity and firmness of the skin. In this condition, the sensor and / or needle may press downward on the skin without immediately piercing it, resulting in improper sensor and / or needle insertion.

[0129] In some embodiments, the base is coupled to the nesting assembly such that the base protrudes from the distal end of the system while the glucose sensor is positioned remotely from the base and within the nesting assembly. This configuration allows the base to prepare the skin for insertion of the sensor and / or needle at the insertion site (e.g., by compressing the skin). Thus, these embodiments can dramatically improve the reliability of sensor and / or needle insertion while reducing pain associated with sensor and / or needle insertion.

[0130] The system can hold the base in a position distal to the glucose sensor module such that the glucose sensor is not attached to the base and such that the glucose sensor can be moved relative to the base. Moving the glucose sensor module distally toward the base can attach the glucose sensor to the base. This movement can occur as a result of compressing the applicator.

[0131] 2 illustrates a perspective view of an applicator system 104 for applying at least a portion of an on-skin sensor assembly 600 (shown in FIG. 4) to the skin of a recipient (e.g., a person). The system can include a sterility barrier having a shell 120 and a cap 122. The cap 122 can thread onto the shell 120 to protect a portion of the system 104 from outside contaminants.

[0132] The electronics unit 500 (e.g., a transmitter with a battery) can be removably coupled to the sterile barrier shell 120. The remaining applicator system 104 can be sterilized, and then the electronics unit 500 can be coupled to the sterile barrier shell 120 (such that the electronics unit 500 is not sterilized by the remaining applicator system 104).

[0133] The user can remove the electronics unit 500 from the sterile barrier shell 120. The user can also couple the electronics unit 500 to the base 128 (as shown in FIG. 6 ) after the applicator system 104 has placed at least a portion of the sensor (for analyte sensing) at a subcutaneous location.

[0134] A number of different sterilization processes can be used with the embodiments described herein. The sterility barrier 120 and / or cap 122 can prevent the passage of gas (e.g., can be hermetically sealed). The hermetic seal can be formed by threads 140 (shown in FIG. 3). The threads 140 can correspond such that they deform to create the seal. The threads 140 can be positioned between the sterility barrier shell 120 and the cap 122.

[0135] The cap 122 can be made of polypropylene and the shell 120 can be made of polycarbonate (or vice versa) such that one of the cap 122 and shell 120 is harder than the other of the cap 122 and shell 120. This difference in hardness (or flexibility) allows one of the components to deform and create a seal for the threads 140.

[0136] In some embodiments, at least one of shell 120 and cap 122 comprises a gas permeable material, allowing sterilizing gas to enter applicator system 104. For example, as illustrated in the context of FIG.

[0137] 3 below, threads 140 can be configured to decouple cap 122 from shell 120 a quarter turn, at least 15 percent of a full turn, and / or at least 50 percent of a full turn. Some embodiments do not include threads 140. In some threaded embodiments, cap 122 can be pressed evenly onto shell 120 (e.g., during assembly).

[0138] The cap 122 can be secured to the shell 120 by a frangible member 142 configured such that removal of the cap 122 from the shell 120 breaks the frangible member 142. The frangible member 142 can be configured like a safety ring (having a weakened portion) on a plastic soda bottle. Loosening the cap from the plastic soda bottle causes the safety ring to separate from the cap of the soda bottle. This approach provides tamper evidence. Similarly, the applicator system 104 can provide tamper evidence (due to the frangible member 142 being broken by removing the cap 122 from the shell 122).

[0139] U.S. Patent Application Publication No. US2013 / 0267811(A1), U.S. Patent Application Publication No. 62 / 165,837, filed May 15, 2015, and U.S. Patent Application No. 62 / 244,520, filed October 21, 2015, contain additional details regarding embodiments of the applicator system. The entire contents of U.S. Patent Application Publication No. US2013 / 0267811(A1), U.S. Patent Application Publication No. 62 / 165,837, and U.S. Patent Application No. 62 / 244,520 are incorporated herein by reference.

[0140] 3 illustrates a cross-sectional view of system 104. Glucose sensor module 134 is configured to couple glucose sensor 138 to base 128 (e.g., "housing"). Nested assembly 132 is positioned in a proximal start position such that glucose sensor module 134 is positioned proximally relative to and distally from base 128. Nested assembly 132 is configured such that compressing nested assembly 132 connects glucose sensor module 134 to base 128 via one or more mechanical interlocks (e.g., snap-fit, interference features).

[0141] The sterile barrier shell 120 is coupled to the nesting assembly 132. After removing the cap 122, the system 104 is configured such that distal compression of the sterile barrier shell 120 (while a distal portion of the system 104 is pressed against the skin) inserts the sensor 138 (shown in FIG. 4 ) into the recipient's skin to position the transdermal glucose analyte sensor 138. In many of the figures shown herein, the sterile barrier shell 120 and cap 122 are hidden to more clearly show other features.

[0142] Collapsing the nested assembly 132 also pushes at least 2.5 millimeters of the glucose sensor 138 through the hole in the base 128 such that at least 2.5 millimeters of the glucose sensor 138, previously positioned proximally relative to the distal end of the base, protrudes distally from the base 128. Thus, in some embodiments, the base 128 can remain stationary relative to the distal portion of the nested assembly 132, while the collapsing motion of the nested assembly 132 moves the glucose sensor module 134 toward the base 128, which then couples the sensor module 134 to the base 128.

[0143] The relative motion of the sensor module 134 and the base 128 has a number of advantages, such as allowing the base to prepare the skin insertion site for insertion of a sensor and / or needle (e.g., by compressing the skin). The starting position of the base 128 also allows the base 128 to protect people from needles that may be positioned within the applicator system 104. For example, if the base 128 were directly coupled to the sensor module 134 at the proximal starting position of the nested assembly, a needle may protrude distally from the base 128. An exposed needle may be potentially dangerous. In contrast, the distal starting position of the base 128 allows the base 128 to protect people from inadvertent needle insertion. Needle protection is especially important for caregivers (who are not the intended recipient of the on-skin sensor assembly 600 shown in FIG. 4 ).

[0144] 4 illustrates a perspective view of an on-skin sensor assembly 600 including a base 128. An adhesive 126 can couple the base 128 to a recipient's skin 130. The adhesive 126 can be a foam adhesive suitable for skin adhesion. The glucose sensor module 134 is configured to couple a glucose sensor 138 to the base 128.

[0145] The applicator system 104 (shown in FIG. 2) can couple the adhesive 126 to the skin 130. The system 104 also secures the glucose sensor module 134 to the base 128 (e.g., coupled via a mechanical interlock, such as a snap fit and / or interference features) to ensure that the glucose sensor 138 is coupled to the base 128. Thus, the adhesive 126 can couple the glucose sensor 138 to the recipient's skin 130.

[0146] After the glucose sensor module 134 is coupled to the base 128, a user (or applicator) can couple an electronics unit 500 (e.g., a transmitter) to the base 128 via a mechanical interlock, such as a snap fit and / or interference features. The electronics unit 500 can measure and / or analyze glucose indicators sensed by the glucose sensor 138. The electronics unit 500 can transmit information (e.g., measurements, analyte data, glucose data) to a remotely located device (e.g., 110-113 shown in FIG. 1).

[0147] 5 illustrates a perspective view of an electronics unit 500 coupled to a base 128 via a mechanical interlock, such as a snap fit and / or interference features. An adhesive 126 on a distal surface of the base 128 is configured to couple the sensor assembly 600 to the skin. FIG 6 illustrates another perspective view of the electronics unit 500 coupled to the base 128.

[0148] Any of the features described in the context of Figures 1-6 may be applied to all aspects and embodiments identified herein. For example, many embodiments may use the on-skin sensor assembly 600 shown in Figure 4 and may use the sterile barrier shell 120 shown in Figure 2. Furthermore, any of the features of an embodiment may be combined in part or in whole independently with other embodiments described herein, such as one, two, or three or more embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of the method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of the system may be configured to perform a method of another aspect or embodiment.

[0149] Figures 7-11 illustrate cross-sectional views of the applicator system 104 from Figure 3. In Figures 7-11, the sterility barrier shell 120 and cap 134 have been hidden to more easily view the nested assembly 132.

[0150] The nesting assembly 132 is part of a system for applying the on-skin sensor assembly 600 to the recipient's skin (shown in FIG. 4). The nesting assembly 132 can apply a portion of the system to the recipient. Additional portions of the system can be added to the on-skin sensor assembly 600 after the applicator system 104 couples an initial portion of the sensor assembly 600 to the recipient. For example, as shown in FIG. 4, the electronics unit 500 (e.g., a transmitter) can be coupled to the on-skin sensor assembly 600 after the applicator system 104 (shown in FIG. 3) couples the base 128, the glucose sensor module 134, and / or the glucose sensor 138 to the recipient's skin 130.

[0151] In some embodiments, the applicator system 104 (shown in FIG. 3 ) couples at least one, at least two, at least three, at least four, and / or all of the following items to the skin of a recipient: electronics unit 500, glucose sensor module 134, glucose sensor 138, base 128, and adhesive 126. The electronics unit 500 can be positioned within the applicator system 104 such that the applicator system 104 is configured to couple the electronics unit 500 to the skin of the recipient.

[0152] FIG. 7 illustrates a nested assembly 132 having a first portion 150 (e.g., a "pusher") configured to move distally relative to a second portion 152 (e.g., a "needle guard") along a path 154 from a proximal start position to a distal position. FIG. 7 illustrates the nested assembly 132 in a proximal start position. FIG. 8 illustrates the nested assembly 132 moving between a proximal start position and a distal position. FIG. 11 illustrates the nested assembly 132 in a distal position. The path 154 (shown in FIG. 7) represents the travel between the proximal start position and the distal position.

[0153] The first set of items may be stationary relative to the first portion 150 and the second set of items may be stationary relative to the second portion 152 while the first set of items are moving relative to the second set of items.

[0154] 7 , the glucose sensor 138 and the sensor module 134 are coupled to the first portion 150 (e.g., such that they are immobile relative to the first portion 150 during the proximal portion of the pathway 154). The base 128 is coupled to the second portion 152 such that the base 128 protrudes from the distal end of the system (e.g., the base protrudes from the distal end of the nested assembly 132). The base 128 includes an adhesive 126 configured to ultimately couple the glucose sensor 138 to the skin (e.g., after at least a portion of the glucose sensor 138 is securely coupled to the base 128).

[0155] 7, glucose sensor 138 and sensor module 134 are positioned within second portion 152 while base 128 protrudes from a distal end of the system (e.g., from a distal end of nested assembly 132) such that the system is configured to couple glucose sensor 138 to base 128 via moving first portion 150 distally relative to second portion 152. The progression shown in FIGS. 7-11 illustrates moving first portion 150 distally relative to second portion 152.

[0156] The sensor module 138 is coupled to a distal portion of the first portion 150 such that moving the first portion 150 to a distal position couples the sensor module 134 to the base 128 (as described above). The glucose sensor 138 is coupled to the sensor module 134 (e.g., is immobile relative to the sensor module 134) while the first portion 150 is positioned in a proximal start position. The glucose sensor 138 can include a distal protruding portion and a proximal portion. The proximal portion can be rigidly coupled to the sensor module 134 such that the proximal portion cannot move relative to the sensor module 134 even if the distal protruding portion can be bent relative to the sensor module 134.

[0157] A needle 156 (e.g., a "C-shaped" needle) is coupled to the first portion 150 such that the glucose sensor 138 and needle 156 move distally relative to the base 128 and relative to the second portion 152. The system may further include a needle release mechanism 158 configured to proximally retract the needle 156.

[0158] The needle 156 has many different configurations. Many different types of needles 156 can be used with the embodiments described herein. Figures 51-55 illustrate various needle embodiments that can be used with any of the embodiments described herein.

[0159] The needle 156 can guide the sensor 138 into the skin of the recipient. A distal portion of the sensor 138 can be positioned within the channel of the needle 156 (as shown in FIG. 42 ). At some times, the distal end of the sensor 138 protrudes from the needle 156 and catches on the recipient's tissue as the sensor 138 and needle 156 are inserted into the recipient. As a result, the sensor 138 may become distorted and not be able to be inserted deep enough into the subcutaneous tissue. In other words, in some embodiments, the sensor wire must be placed within the channel of the C-shaped needle 156 that is guided into the tissue and must be held within the channel 330 during deployment.

[0160] The risk of the sensor 138 protruding from the channel 330 (and thereby failing to be properly inserted into the recipient) can be greatly reduced by the embodiment illustrated in Figure 51. In this embodiment, an adhesive 376 adheres the distal portion of the glucose sensor 138 to the channel 330 of the needle 156. Retracting the needle 156 can break the adhesion of the adhesive 376, allowing the distal portion of the sensor 138 to remain in a subcutaneous location while the needle 156 is retracted (and even after the needle 156 is retracted).

[0161] The risk of the sensor 138 protruding from the channel 330 (and thereby being unable to be properly inserted into the recipient) can be greatly reduced by the embodiment illustrated in Figures 52 and 53. In this embodiment, the needle 156a comprises two sides which can be separated by a slot 378. The sensor 138 can have a width wider than the width of the slot 378 such that the sensor 138 cannot emerge from the channel 330a until the two sides of the needle 156a move apart (widening the slot 378).

[0162] 54 may be used with any of the other embodiments described herein. The needle 156b includes a ramp 380 at a distal end of the channel 330b. The distal end of the needle 156b may include a conical tip 382. The ramp 380 may be configured to push the sensor 138 out of the channel 330b of the needle 156b as the needle 156b is retracted into the nesting assembly 132 (shown in FIG. 7).

[0163] FIG. 55 illustrates a cross-sectional view of different needles 156c, 156d, 156e, 156f that can be used as needle 156 in FIG. 7 or in any other embodiment described herein. Needle 156c includes a sealed channel 330c. Needles 156d, 156e, 156f are C-shaped needles, although in some embodiments, numerous other C-shaped needles can be used. The ends of needle 156d can be angled relative to each other. In some embodiments, the ends of the needles can be angled away from each other in an opposing manner as shown by 156d. In some embodiments, the ends of the needles can have flared edges that are rounded to prevent the sensor from contacting the sharp edges. The ends of needle 156e can be parallel and / or flat relative to each other. The outer portion of channel 330f may be formed by walls that are straight and / or parallel to one another (rather than by curved walls as in the case of other needles 156d, 156e). Some needles 156d may be manufactured via laser cutting, some needles 156e may be manufactured via wire electrical discharge machining ("EDM"), and some needles 156f may be manufactured via stamping.

[0164] 7, a needle hub 162 is coupled to the needle 156. The needle hub includes an outwardly protruding release feature 160. In some embodiments, the release feature can include one, two, or more flexible arms. An outer edge 164 of the release feature 160 hooks into an inwardly facing overhang 166 (e.g., undercut, detent) of the first portion 150 such that moving the first portion 150 distally relative to the second portion 152 moves the needle retraction mechanism 158 distally to a release point.

[0165] At the release point, the proximal protrusion 170 of the second portion 152 engages the release feature 160 (shown in FIG. 9 ), which bends the release mechanism 160 inward (shown in FIG. 10 ) until the release feature 160 no longer catches on the overhang 166 of the first portion 150. Once the release feature 160 no longer catches on the overhang 166 of the first portion 150, the spring 234 of the needle retraction mechanism 158 pushes the needle 156 and needle hub 162 proximally against the first portion 150 and against the second portion 152 (shown in FIG. 11 ) until the needle no longer protrudes distally from the base 128 and is completely hidden within the nested assembly 132.

[0166] 7 to create an embodiment that does not include a needle. Thus, the needle 156 is not used in some embodiments. For example, the distal end of the glucose sensor 138 can be formed with a cone shape to allow the glucose sensor 138 to be inserted into the skin without the use of the needle 156. Unless otherwise noted, the embodiments described herein can be formed with or without the needle 156.

[0167] In some embodiments, the needle can help guide the glucose sensor 138 (e.g., at least a distal portion of the glucose sensor) into the skin. In some embodiments, the needle is not part of the system and is not used to help guide the glucose sensor 138 into the skin. In needle and needle-free embodiments, puncturing the skin is an important consideration. Failure to properly puncture the skin can lead to improper placement of the glucose sensor 138.

[0168] Tensioning the skin prior to piercing the skin with the glucose sensor 138 and / or needle 156 can dramatically improve the reliability of achieving proper placement of the glucose sensor 138. Tensioning the skin can be achieved by compressing the skin with a distally protruding shape (e.g., a convex shape) prior to and at the moment of piercing the skin with the glucose sensor 138 and / or needle 156.

[0169] 12A illustrates a portion of the cross-section shown in FIG. 7. The base 128 includes an optional distally-facing protrusion 174 positioned distally relative to the second portion 152 (and relative to the remainder of the nested assembly 132). The distal protrusion 174 is convex and dome-shaped. In some embodiments, the distal protrusion 174 has a block shape, a star shape, and a cylindrical shape. Some embodiments of the base 128 do not include the protrusion 174.

[0170] Distal protrusion 174 can be positioned distal to any other portion of base 128. Distal protrusion 174 can extend through hole 176 into adhesive 126 (also shown in FIG. 5 ). A distal portion of convex protrusion 174 can be positioned distal to adhesive 126, while a proximal portion of convex protrusion 174 can be positioned proximal to adhesive 126.

[0171] The distal projection 174 has an aperture 180 through which the needle 156 and / or the glucose sensor 138 can pass. The distal projection 174 can compress the skin such that the distal projection 174 is configured to reduce the resistance of the skin to puncture.

[0172] Figure 12B illustrates a cross-sectional view of base 128b, which is the same as base 128 illustrated in Figures 7 and 12B, except for the following features: Base 128b does not include protrusion 174. Base 128b includes a funnel 186 (e.g., radius) on the distal side of hole 180b.

[0173] Similar to the embodiment shown in Figure 12A, a sensor 138 (e.g., an analyte sensor) and / or needle 156 (shown in Figure 12A) can pass through hole 180b (shown in Figure 12B). Funnels 182, 186 can be mirror images of each other or can be different shapes. Base 128b can be used with any of the embodiments described herein.

[0174] 13 illustrates a perspective view of a portion of the adhesive 126. The needle 156 has a number of different shapes and cross sections. In some embodiments, the needle 156 includes a slot 184 (e.g., channel 330 shown in FIGS. 42 and 43) in which at least a portion of the glucose sensor 138 can be placed.

[0175] A needle 156 having a slot 184 passes through a hole 180 in the distal projection and a hole 176 in the adhesive 126. A portion of the glucose sensor 138 is positioned within the slot 184 such that the needle 156 is configured to move distally relative to the base 128 (shown in FIG. 12A ) without displacing the portion of the glucose sensor 138 out of the slot 184. The distal projection 174 is convex such that the distal projection 174 is configured to apply tension to the skin while the first portion 150 of the nesting assembly 132 (shown in FIG. 7 ) moves distally relative to the second portion 152 in preparation for piercing the skin.

[0176] As noted above, the adhesive 126 includes a hole 176 through which at least a portion of the distal projection 174 of the base 128 can pass. The distal projection 174 is positioned within the hole 176 of the adhesive 126 such that the distal projection 174 can apply tension to at least a portion of the skin within a second hole (e.g., positioned below the hole 176). The hole 176 can be circular or any other suitable shape. The hole 176 can be sized such that at least a majority of the distal projection 174 extends through the hole 176. The outer periphery of the hole 176 can be positioned outside the projection 174 such that the outer periphery of the hole 176 is positioned radially outward relative to the outer periphery of the projection 174 that connects the distal projection 174 with the remainder of the base 128.

[0177] In some embodiments, the holes 176 in the adhesive 126 are large enough that the adhesive 126 does not cover any of the distal projections 174. In some embodiments, the adhesive 126 covers at least a portion, or even a majority, of the distal projections 174. Thus, the adhesive 126 need not be flat and can be distally raised in the area above the distal projections 174.

[0178] In some embodiments, the adhesive 126 has a non-uniform thickness such that the thickness of the adhesive 126 is greater in an area surrounding the needle exit area than in other areas further radially outward from the needle exit area. Thus, the distal projection 174 may be part of the adhesive 126 rather than part of the base 128. However, in some embodiments, the base 128 comprises the adhesive 126 and the distal projection 174 may be formed by the plastic of the base 128 or by the foamed adhesive 126 of the base 128.

[0179] The needle 156 includes a distal end 198 and a heel 194. The heel 194 is the proximal end of an angled portion of the needle tip. The purpose of the angled portion is to form a sharpened end to facilitate penetration of tissue. The sensor 138 has a distal end 208.

[0180] During insertion of the needle 156 and sensor 138 into tissue, as the needle 156 and sensor 138 initially protrude distally from the system and / or while the needle 156 and sensor 138 are positioned within the nested assembly, the end 208 of the sensor 138 can be positioned at least 0.1 mm proximal to the heel 194, at least 1 mm proximal to the heel 194, at least 3 mm proximal to the heel 194, and / or within ±5 mm of the heel 194, and / or the end 208 of the sensor 138 can be positioned at least 0.3 mm proximal to the distal end 198 of the needle 156 and / or less than 2 mm proximal to the distal end 198.

[0181] 12A , distal protrusion 174 can protrude at least 0.5 millimeters and less than 5 millimeters from the distal face of adhesive 126. In embodiments in which adhesive 126 has a non-planar distal surface, distal protrusion 174 can protrude at least 0.5 millimeters and less than 5 millimeters from the average distal location of adhesive 126.

[0182] As explained above, in some embodiments, the base is coupled to the nested assembly such that the glucose sensor is positioned remotely from the base and protrudes from the distal end of the system while positioned within the nested assembly, however, in other embodiments, the base is coupled to the nested assembly such that as the first portion moves distally relative to the second portion of the nested assembly, the base is positioned completely within the nested assembly and moves distally with the sensor.

[0183] For example, FIG. 59 illustrates the base 128 coupled to the sensor module 134 and to the sensor 138 while the first portion 150 of the nested assembly 132f is positioned in a proximal start position. The base 128 moves distally as the first portion 150 moves distally relative to the second portion 152. The base 128 can be coupled to a distal end portion of the first portion 150 while the first portion 150 is positioned in the proximal start position. All of the features and embodiments described herein can be configured and used in conjunction with the positioning of the base 128 described in the context of FIG.

[0184] All of the embodiments described herein can be used with a base coupled to the nested assembly such that the base is positioned completely within the nested assembly and moves distally with the sensor as the first portion moves distally relative to the second portion of the nested assembly. All of the embodiments described herein can be used with a base coupled to the nested assembly such that the base protrudes from the distal end of the system while the glucose sensor is positioned remote from the base and within the nested assembly.

[0185] Sensor Module Docking and Base Removal As explained above, maintaining the base against the skin during insertion of the sensor and / or needle allows for significant medical benefits. However, maintaining the base against the skin may require the sensor to move relative to the base during the insertion process. Once inserted, the sensor needs to be coupled to the base to prevent the sensor from being inadvertently dislodged from the base. Thus, a need exists for a system that allows the sensor to be moved relative to the base (without being undue burden to the user) and yet allows the sensor to be locked to the base.

[0186] Maintaining the base against the skin during distal movement of the sensor and / or needle is made possible in many embodiments by a unique coupling system that secures the sensor (and sensor module) to a first portion of the nested assembly and secures the base to a second portion of the nested assembly. Moving the first portion toward the second portion of the nested assembly can align the sensor with the base while temporarily holding the sensor. The system can then couple the sensor to the base. Finally, the system can detach the base and sensor from the nested assembly (which can be disposable or reusable with different sensors).

[0187] 4, the sensor module 134 and glucose sensor 138 are not initially coupled to the base 128. Coupling the sensor module 134 and glucose sensor 138 to the base 128 via compressing the nested assembly 132 and prior to removing the base 128 from the nested assembly 132 can be a significant challenge, but is made possible by many of the embodiments described herein.

[0188] 7 and 14, the sensor module 134 (and glucose sensor 138) can be positioned remotely from the base 128, even if they are indirectly coupled via the nested assembly 132. In other words, the sensor module 134 (and glucose sensor 138) can be coupled to the first portion 150 of the nested assembly 132, while the base 128 is coupled to the second portion 152 of the nested assembly 132. In this state, the sensor module 134 and glucose sensor 138 can be moved relative to the base 128 (e.g., such that the sensor module 134 and glucose sensor 138 move along a path from a proximal start position to a distal position to "dock" the sensor module 134 and glucose sensor 138 to the base 128).

[0189] After the sensor module 134 and glucose sensor 138 are "docked" with the base 128, the system can remove the base 128 from the nested assembly 132 and allow the sensor module 134, glucose sensor 138, and base 128 to be attached to the skin via the adhesive 126, while the nested assembly 132 and other parts of the system can be discarded.

[0190] As shown in FIGURE 7, the sensor module 134 is coupled to the first portion 150 while the first portion 150 is in a proximal start position and is positioned at least 5 millimeters from the base 128. The system is configured such that moving the first portion 150 toward a distal position (as shown in FIGURE 11) couples the sensor module 134 to the base 128. The glucose sensor 138 is coupled to the sensor module 134 while the first portion 150 is positioned in the proximal start position. The glucose sensor 138 is positioned within the second portion 152 while the base 128 protrudes from the distal end of the system.

[0191] Arrow 188 illustrates the proximal direction in Figure 7. Arrow 190 illustrates the distal direction in Figure 7. Line 172 illustrates the horizontal direction. As used herein, horizontal means within ±20 degrees of perpendicular to central axis 196.

[0192] Figure 15 illustrates a perspective view of a cross section of a portion of the system shown in Figure 7. The cross section is cut through hole 180 in base 128. The visible portion includes sensor module 134, sensor 138, encapsulant 192, needle 156, base 128, and adhesive 126. Sensor module 134 is in a proximal start position. encapsulant 192 is configured to prevent fluids (e.g., bodily fluids) from entering glucose sensor module 134.

[0193] The glucose sensor 138 is mechanically coupled to the sensor module 134. The glucose sensor 138 extends into an interior portion of the sensor module 134 and is electrically coupled to an interconnect at the interior portion of the sensor module 134. In FIG. 15, the interconnect is hidden to more easily view the proximal portion of the glucose sensor 138 within the interior portion of the sensor module 134. Also, in FIG. 15, many other portions of the system are hidden to allow clear observation of the visible portions.

[0194] In numerous embodiments, the sensor module 134 moves from the position shown in FIG. 15 until the sensor module 134 snaps into the base 128 via a snap fit, which will be described in more detail below. FIG. 11 illustrates the sensor module 134 snapped into the base 128. This movement from a proximal starting position to a "docked" position can be accomplished by moving along a path 154 (shown in FIG. 7 and whose progression is illustrated in FIGS. 7-11). (The arrows representing path 154 are not necessarily drawn to scale.)

[0195] 7 and 15 , the sensor module 134 is stationary relative to the first portion 150 during a first portion of the path 154, and the base 128 is stationary relative to the second portion 152 of the nested assembly 132. The system is configured to move the first portion 150 distally relative to the second portion 152 during the second portion of the path 154, move the sensor module 134 toward the base 128, move a portion of the sensor 138 through the hole 180 in the base 128, couple the sensor module 134 to the base 128, and enable removal of the coupled sensor module 134 and base 128 from the nested assembly 132.

[0196] 7 illustrates a vertical central axis 196 oriented from the proximal end to the distal end of the system. (In FIG. 7, a portion of central axis 196 is hidden to avoid obscuring the arrow representing pathway 154 and to avoid obscuring needle 156.)

[0197] 15 illustrates the flex arm 202 of the sensor module 134. The flex arm 202 is oriented horizontally and configured to secure the sensor module 134 to a protruding portion of the base 128. In some embodiments, the flex arm 202 is an alignment arm to prevent and / or hinder rotation of the sensor module 134 relative to the base 128.

[0198] 16 illustrates a cross-sectional perspective view of the sensor module 134 coupled to the base 128 via the flex arm 202. An interconnect 204 protrudes proximally to connect the sensor module 134 to an electronics unit 500 (e.g., a transmitter).

[0199] 15 and 16, the flex arm 202 extends from the periphery of the sensor module 134. The base 128 includes a protrusion 206 that extends from a horizontal portion of the planar surface of the base 128.

[0200] 16 , each of the proximal projections 206 of the base 128 is coupled to a flex arm 202 of the sensor module 134. Thus, coupling of the proximal projections 206 to the flex arms 202 couples the sensor module 134 to the base 128.

[0201] Each proximal protrusion 206 can include a locking protrusion 212 that extends at an angle of at least 45 degrees from a central axis of each proximal protrusion 206. In some embodiments, the locking protrusions 212 extend horizontally (e.g., as shown in FIG. 15 ). Each horizontal locking protrusion 212 is coupled to an end portion 210 of the flexible arm 202.

[0202] End portion 210 of each flexible arm 202 may extend at an angle greater than 45 degrees and less than 135 degrees relative to a central axis of the majority of flexible arm 202. End portion 210 of each flexible arm 202 may include a horizontal locking protrusion (e.g., as shown in FIG. 15).

[0203] 15 and 16, the first horizontal locking protrusion is coupled to the end portion 210 of the first flexible arm 202. The second horizontal locking protrusion 212 is coupled to the first proximal protrusion 206 of the base 128. In FIG. 16, the first horizontal locking protrusion is positioned distally below the second horizontal locking protrusion 212 to secure the sensor module 134 to the base 128. The system is configured such that moving the first portion 150 of the nestable assembly 132 to a distal position (shown in FIG. 11) bends the first flex arm 202 to allow the first horizontal locking protrusion of the flex arm 202 to move distally relative to the second horizontal locking protrusion 212. Thus, the flex arm 202 is secured between the locking protrusion 212 and the distal surface of the base 128.

[0204] At least a portion of the flex arm 202 (e.g., end portion 210) is positioned distally under the horizontal locking protrusion 212 of the base 128 to secure the sensor module 134 to the base 128. The system is configured such that moving the first portion 150 of the nestable assembly 132 to a distal position causes the flex arm 202 (e.g., end portion 210) to bend (e.g., outwardly) from the remainder of the sensor module 134 to allow the horizontal locking protrusion of the flex arm 202 to travel around the locking protrusion 212 of the proximal protrusion 206. Thus, at least a portion of the flex arm 202 can be moved distally relative to the horizontal locking protrusion 212 of the proximal protrusion 206 of the base 128.

[0205] The sensor module 134 can have a number of flex arms 202, and the base can have a number of proximal protrusions 206 configured to couple the sensor module 134 to the base 128. In some embodiments, the first flex arm 202 is positioned on an opposite side of the sensor module 134 to the second flex arm 202 (e.g., as shown in FIGS. 15 and 16 ).

[0206] In some embodiments, the base 128 includes a flex arm (e.g., like flex arm 202 shown in FIGS. 15 and 16 ) and the sensor module 134 includes a protrusion that couples to the flex arm of the base 128. The protrusion of the sensor module 134 may be similar to the protrusion 206 shown in FIGS. 15 and 16 , except that in some embodiments, the protrusion extends distally toward the flex arm of the base 128. Thus, the base 128 may be coupled to the sensor module 134 by a flex arm and a mating protrusion, regardless of whether the base 128 or the sensor module 134 includes a flex arm.

[0207] In some embodiments, the sensor module is coupled to the glucose sensor. The system comprises a vertical central axis oriented from the proximal end to the distal end of the system. The base comprises a first flex arm oriented horizontally and coupled to the sensor module. The sensor module comprises a first distal protrusion coupled to the first flex arm to couple the sensor module to the base. The first horizontal locking protrusion is coupled to an end portion of the first flexible arm. The second horizontal locking protrusion is coupled to the first distal protrusion of the sensor module. The second horizontal locking protrusion is positioned distally below the first horizontal locking protrusion to secure the sensor module to the base. The system is configured such that moving the first portion of the nested assembly to a distal position bends the first flex arm to allow the second horizontal locking protrusion to move distally relative to the first horizontal locking protrusion. The sensor module comprises a second distal protrusion coupled to the second flex arm of the base. The first distal projection is positioned on an opposite side of the sensor module from the second distal projection.

[0208] Docking the sensor module 134 to the base 128 may include securing the sensor module 134 to the first portion 150 of the nested assembly 132 while the first portion 150 moves the sensor module 134 towards the base 128. This securing of the sensor module 134 to the first portion 150 of the nested assembly 132 needs to be reliable, but temporary so that the sensor module 134 can be removed from the first portion 150 at an appropriate stage. The structure that secures the sensor module 134 to the first portion 150 of the nested assembly 132 generally needs to avoid interfering with the docking process.

[0209] 17 illustrates a cross-sectional view of the first portion 150 of the nesting assembly 132. FIG. 17 shows the glucose sensor module 134 and the needle 156. Some embodiments do not include the needle 156. In FIG. 17, a number of items have been hidden to provide a clear view of the flex arms 214, 216 of the first portion 150.

[0210] The first portion 150 includes a first flex arm 214 and a second flex arm 216 that protrude distally and latch onto the sensor module 134 to releasably secure the sensor module 134 in the first portion 150 while the first portion 150 is in the proximal start position (shown in FIG. 7 ). The flex arms 214, 216 can be coupled to a periphery of the sensor module 134 such that the distal ends of the flex arms 214, 216 wrap around a distal face of the sensor module 134. In some embodiments, the distal ends of the flex arms 214, 216 are positioned distal to the sensor module 134 while the first portion 150 is in the proximal start position.

[0211] 17, the base 128 is hidden, but in the state depicted in FIG 17, the sensor module 134 is positioned remotely from the base 128 while the first portion 150 is in a proximal starting position, providing a distance of at least 3 millimeters from the sensor module 134 to the base 128. This distance may be important to allow the base to rest on the skin as the needle 156 and / or glucose sensor 138 pierce and advance into the skin during transdermal insertion.

[0212] 7 and 17, the sensor module 134 is positioned within the second portion 152 while the base 128 protrudes from the distal end of the system such that the system is configured to couple the sensor module 134 to the base 128 via moving the first portion 150 distally relative to the second portion 152. The sensor module 134 is positioned within the second portion 152 while the base 128 protrudes from the distal end of the system, even though the sensor module 134 is movable relative to the second portion 152 of the nested assembly 132. Thus, the first portion 150 moves the sensor module 134 through an interior region of the second portion 152 of the nested assembly 132 without moving the base 128 through the interior region of the second portion 152.

[0213] The system includes a vertical central axis 196 oriented from the proximal end to the distal end of the system. First flex arm 214 and second flex arm 216 of first portion 150 secure sensor module 134 to first portion 150 such that sensor module 134 is releasably engaged to first portion 150 with a first vertical retention strength (measured along vertical central axis 196).

[0214] 15 and 16, the sensor module 134 is coupled to the base 128 via at least one flex arm 202 such that the sensor module 134 is coupled to the base 128 with a second vertical retention strength. The flex arm 202 can extend from a perimeter of the sensor module 134. The flex arm 202 can be part of the base 128.

[0215] Referring now to FIG. 17 , in some embodiments, the second vertical retention strength is greater than the first vertical retention strength such that continuing to push the first portion 150 distally once the sensor module 134 is coupled to the base 128 overcomes the first and second flex arms 214, 216 of the first portion 150 and removes the sensor module 134 from the first portion 150.

[0216] In some embodiments, the second vertical retention strength is at least 50 percent greater than the first vertical retention strength. In some embodiments, the second vertical retention strength is at least 100 percent greater than the first vertical retention strength. In some embodiments, the second vertical retention strength is less than 400 percent greater than the first vertical retention strength.

[0217] 6 illustrates an on-skin sensor assembly 600 attached to a recipient. The on-skin sensor assembly 600 can include a glucose sensor 138 and / or a sensor module 134 (shown in FIG. 7 ). In some embodiments, the on-skin sensor assembly 600 includes a needle 156. However, in some embodiments, the on-skin sensor assembly 600 does not include a needle 156.

[0218] As explained above, maintaining the base against the skin during insertion of the sensor and / or needle can provide significant medical benefits. However, maintaining the base against the skin can make it difficult to remove the base from the applicator. For example, in some prior art systems, the base is removed after it has moved distally downward with the needle. This relatively long stroke can enable some base removal mechanisms. In contrast, releasing the base can be problematic when maintaining the base in a fixed position as the needle moves toward the base.

[0219] Many embodiments described herein allow for maintaining the base 128 against the skin during insertion of the sensor 138 and / or needle 156. As discussed above in the context of Figures 7-11, after the sensor module 134 is coupled to the base 128, the sensor module 134 and base 128 may need to be removed from the nested assembly 132 to secure the glucose sensor 138 to the recipient and to allow the nested assembly to be discarded, recycled, or reused.

[0220] As shown in FIGS. 7-11, some embodiments hold the base 128 in a fixed position relative to the second portion 152 of the nested assembly 132 as the sensor module 134 moves towards the base 128. Referring now to FIG. 18, once the sensor module 134 is attached to the base 128, the system can release the base 128 by bending the flex arm 220 that couples the base 128 to the second portion 152. FIG. 18 shows the system prior to the sensor module 134 docking with the base 128 to illustrate the distal protrusion 222 of the first portion 150 aligned with the flex arm 220 such that the distal protrusion 222 is configured to bend the flex arm 220 (via the distal protrusion 222 contacting the flex arm 220).

[0221] The distal projection 222 bends the flex arm 220 to remove the base 128 from the nested assembly 132 (shown in FIG. 7 ) after the sensor module 134 is coupled to the base 128 (as shown in FIGS. 11 and 16 ). The flex arm 220 can include a ramp portion 224. The distal end of the distal projection 222 can contact the ramp portion 224, as shown by arrow 228 in FIG. 18 , and then continue to move distally to bend the flex arm 220 distally. This bending can disengage the flex arm 220 from the locking feature 230 of the base 128. This unlocking is accomplished by moving the first portion 150 distally relative to the second portion 152, which moves the distal projection 222, as shown by arrow 226.

[0222] 18 is that the unlocking movement (of arm 220 bending as shown by arrow 228) is perpendicular (within ±20 degrees) to the input force (e.g., as represented by arrow 226). Thus, the system can be designed such that the maximum retention capacity (e.g., of locking feature 230) is many times greater than the force required to unlock arm 220 from base 128. As a result, the system can be made extremely reliable and less susceptible to manufacturing variability and normal use variability.

[0223] In contrast, when the retaining force and unlocking force are oriented along the same axis (e.g., within ±20 degrees), the retaining force is typically less than or equal to the unlocking force. However, the unique structure shown in FIG. 18 allows the retaining force to be at least two times greater than the unlocking force (and in some cases at least four times greater). As a result, the system can prevent inadvertent unlocking of the base 128, while having an unlocking force that is low enough to be easily provided by the user or by another part of the system (e.g., a motor).

[0224] Another advantage of this system is that it controls the sequence of locking and unlocking operations. In other words, the structure ensures that premature locking and unlocking do not occur. In medical situations, where reliability is paramount, this control is extremely beneficial. For example, in some embodiments, the process follows the following sequence: The sensor module 134 couples to the base 128. The first portion 150 then releases the sensor module 134. The second portion 152 then releases the base 128. In some embodiments, the vertical locations of the various locking and unlocking structures are optimized to ensure that this sequence is the only sequence in which the first portion 150 is capable of moving from a proximal start position to a distal position along the path previously described. (Some embodiments use a different locking and unlocking sequence of operations.)

[0225] 7 illustrates the base 128 protruding from the distal end of the system while the first portion 150 of the nested assembly 132 is positioned in a proximal start position. The sensor module 134 and at least a majority of the glucose sensor 138 are positioned remotely relative to the base 128. The system is configured to couple the sensor module 134 and the glucose sensor 138 to the base 128 via moving the first portion 150 distally relative to the second portion 152.

[0226] 18 and 19, the base 128 includes a first radial protrusion 230 (e.g., a locking feature) releasably coupled with a second radial protrusion 232 (e.g., a locking feature) of the second portion 152 of the nestable assembly 132 (shown in FIG. 7) with a first vertical retention force. The first radial protrusion 230 protrudes inwardly and the second radial protrusion 232 protrudes outwardly. The system is configured such that moving the first portion 150 to a distal position moves the second radial protrusion 232 relative to the first radial protrusion 230 to remove the base 128 from the nestable assembly 132.

[0227] The first portion 150 of the nestable assembly 132 includes a first arm 222 that projects distally. The second portion 152 of the nestable assembly 132 includes a second flex arm 220 that projects distally. The first arm 222 and the second flex arm 220 can be oriented within 25 degrees of each other (as measured between their central axes). The system is configured such that moving the first portion 150 along the path 154 (shown in FIG. 7 ) from a proximal start position to a distal position causes the first arm 222 to deflect the second flex arm 220, thereby enabling the second flex arm 220 to detach the base 128 and decouple the base 128 from the nestable assembly 132 (shown in FIG. 7 ). Thus, the flex arm 220 is configured to releasably couple the second portion 152 to the base 128.

[0228] When the first portion 150 is in a proximal starting position, the first arm 222 of the first portion 150 is at least partially vertically aligned with the second flex arm 220 of the second portion 152 to allow the first arm 222 to deflect the second flex arm 220 as the first portion moves to a distal position.

[0229] The first arm 222 and the second arm 220 can be oriented distally such that at least a portion of the first arm 222 is positioned proximally over a protrusion (e.g., ramp portion 224) of the second arm 220. The protrusion can be configured to allow a collision between the first arm 222 and the protrusion to deflect the second arm 220 (to detach the base 128 from the second portion 152).

[0230] 18, when first portion 150 is in the proximal start position, at least a section of first arm 222 is positioned directly over at least a portion of second flex arm 220 to allow first arm 222 to deflect second flex arm 220 as first portion 150 moves to the distal position described above. Second flex arm 220 includes a first horizontal protrusion (e.g., locking feature 232). Base 128 includes a second horizontal protrusion (e.g., locking feature 230) that latches with the first horizontal protrusion to couple base 128 to second portion 152 of nestable assembly 132. The first arm 222 of the first portion 150 deflects the second flex arm 220 of the second portion 152 to unlatch the base 128 from the second portion 152 and, in turn, to unlatch the base 128 from the nested assembly 132.

[0231] 7, the system is configured to couple the glucose sensor 138 to the base 128 in a first position. The system is configured to detach the base 128 from the nested assembly 132 in a second position that is distal to the first position.

[0232] A third flex arm (e.g., flex arm 202 in FIG. 15) couples the glucose sensor 138 to the base 128 in a first position. A second flex arm (e.g., flex arm 220 in FIG. 18) detaches from the base in a second position. The second position is distal to the first position such that the system is configured to secure the base 128 to the nested assembly 132 until after the glucose sensor 138 is secured to the base 128.

[0233] Spring Compression Needles used in glucose sensor insertion applicators can be dangerous. For example, an accidental needle stick can transmit disease. Using a spring to retract the needle can reduce the risk of needle injury.

[0234] 7, a spring 234 (e.g., a coil spring) can be used to retract the needle hub 162 that supports the C-shaped needle 156. The needle hub 162 can be released at the bottom of the insertion depth (to allow the needle 156 to be retracted). For example, when the needle 156 reaches a maximum distal position, a latch 236 can be released to allow the spring 234 to push the needle 156 proximally into a protective housing (e.g., into the first part 150, which can be a protective housing).

[0235] Many applicators use pre-compressed springs. Many applicators use a substantially uncompressed spring that is compressed by the user when the user compresses the applicator. One disadvantage of a pre-compressed spring is that the spring force can cause components to creep (e.g., change shape over time), which can compromise the reliability of the design. One disadvantage of an uncompressed spring is that the first and second parts of the nested assembly can move slightly freely relative to each other (when the assembly is in the proximal start position). This "chattering" of the first and second parts can make the assembly appear weak and brittle.

[0236] Many of the components described herein can be molded from plastic (although the springs are often metal). Preventing creep in plastic components can help ensure that the applicator functions the same as when manufactured and after an extended period of time. One way to reduce the risk of creep is to not place parts under loads (e.g., during storage) that are large enough to deform the plastic during storage.

[0237] Producing stored energy by storing energy in a spring during deployment limits the sustained load on the system. For example, the spring storage force can be generated at least in part by compressing a nested assembly (rather than storing the system with the large storage force of a fully pre-compressed spring).

[0238] Transcutaneous and implantable sensors are subject to in vivo characteristics and physiological responses in the surrounding tissue. For example, a decrease in sensor accuracy after the sensor is implanted is one common phenomenon that is commonly observed. This phenomenon is sometimes referred to as the "drop recovery" process. Drop recovery is thought to be triggered by the trauma of the insertion of the implantable sensor and possibly by stimulation of nerve bundles near the implantation area, which results in the nerve bundles reducing blood flow to the implantation area.

[0239] Alternatively, drop recovery may be associated with damage to nearby blood vessels, resulting in a vasospastic event. Any local cessation of blood flow in the implant area for a period of time leads to a reduction in the amount of glucose in the area of ​​the sensor. During this time, the sensor has reduced sensitivity and is unable to track glucose accurately. Drop recovery therefore manifests as a suppressed glucose signal. The suppressed signal from drop recovery often appears in the signal within the first day after implantation, and most commonly appears within the first 12 hours after implantation. Drop recovery usually resolves within 6-8 hours.

[0240] Identification of drop recovery can provide the patient, physician, or other user with information that the sensor is only temporarily affected by a short-term physiological response and that there is no need to remove the implant since normal function may return within a few hours.

[0241] Minimizing the time the needle is in the body limits the opportunity for tissue trauma that can lead to phenomena such as drop recovery. Rapid needle retraction helps limit the time the needle is in the body. A large spring retraction force allows the needle to be retracted quickly.

[0242] 7 solves the "chatter" problem, avoids significant creep, and allows for quick needle retraction. The embodiment places a slightly preloaded spring 234 between the first portion 150 and the second portion 152 of the nested assembly 132. In other words, when the first portion 150 is in the proximal start position, the spring 234 is in a slightly compressed state because the relaxed length of the spring 234 is longer than the length of the chamber in which the spring 234 resides within the nested assembly 132.

[0243] In some embodiments, the relaxed length of the spring 234 is at least 4 percent longer than the length of the chamber. In some embodiments, the relaxed length of the spring 234 is at least 9 percent longer than the length of the chamber. In some embodiments, the relaxed length of the spring 234 is less than 18 percent longer than the length of the chamber. In some embodiments, the relaxed length of the spring 234 is less than 30 percent longer than the length of the chamber.

[0244] The spring 234 is further compressed as the first portion 150 moves distally relative to the second portion 152. In some embodiments, this slight preload has a compressed length that is much shorter than the compressed length of a typical fully pre-compressed spring. In some embodiments, the preload causes a compressed length of the spring 234 that is less than 25 percent of the compressed length of a fully compressed spring 234. In some embodiments, the preload causes a compressed length of the spring 234 that is greater than 3 percent of the compressed length of a fully compressed spring 234. The slight preload eliminates "chattering" while having too little force to cause significant creep of non-spring components in the system.

[0245] The spring 234 can be inserted into the first part 150 through a hole 238 in the proximal end of the first part 150. The needle hub 162 (and attached C-shaped needle 156) is then loaded through the proximal side of the first part 150 of the nested assembly (e.g., through the hole 238 in the proximal end of the first part 150).

[0246] The needle hub 162 slides through the first part 150 until a radial snap (e.g., release feature 160 of the needle hub 162) engages a section of the first part 150 (see latch 236). Thus, the spring 234 is positioned between the needle hub 162 and the distal portion of the first part 150 of the nesting assembly 132 with a slight preload.

[0247] The spring 234 is further compressed during actuation and telescoping of the applicator (e.g., while compressing the first portion 150 into the second portion 152). At the bottom of the stroke (e.g., at the distal end position), the radial snap of the needle hub 162 is forced radially inward by features (e.g., protrusions 170) in the telescoping assembly 132 (as shown by the progression of FIGS. 7-11). This releases the needle hub 162, allowing the spring 234 to expand and drive the needle 156 proximally of the recipient (and into the first portion 150 and / or second portion 152).

[0248] 7, the base 128 protrudes from the distal end of the system while a first portion 150 of the nested assembly 132 is positioned in a proximal start position and the glucose sensor 138 is positioned remotely relative to the base 128. The glucose sensor 138 is movably coupled to the base 128 via the nested assembly 132, as the glucose sensor 138 is coupled to the first portion 150 and the base 128 is coupled to the second portion 152 of the nested assembly 132.

[0249] The system includes a spring 234 configured to store a needle 156. The needle 156 is configured to facilitate inserting the glucose sensor 138 into the skin. In some embodiments, the system does not include the needle 156.

[0250] When the first portion 150 is in the proximal start position, the spring 234 is in a first compressed state. The system is configured such that moving the first portion 150 distally from the proximal start position increases the compression of the spring 234. The first compressed state places the first portion 150 and the second portion 152 in a tensioned state. The latch engagement feature holds the first portion 150 and the second portion 152 in a tensioned state. In other words, in the proximal start position, the latch engagement feature is configured to prevent the spring 234 from pushing the first portion 150 proximally relative to the second portion 152. The latch engagement feature resists the first compressed state.

[0251] In some embodiments, the potential energy of the first compressed state is less than the amount of potential energy required to retract needle 156. This low potential energy of a partially pre-compressed spring 234 is typically insufficient to cause creep, and more typically sufficient to eliminate the "chatter" described above.

[0252] A redundant system can help ensure that needle 156 (and in some cases sensor 138) can always be removed from the recipient after they have been inserted into the recipient. In extreme cases, if the required needle removal force is greater than the spring retraction force, the user can pull the entire nested assembly 132 proximally to remove needle 156 and / or sensor 138 from the recipient.

[0253] Some embodiments include a secondary storage spring. In other words, in some embodiments, spring 234 of FIG. 7 is actually two concentric springs. (In some embodiments, spring 234 is actually just one spring.) The secondary spring can be shorter than the primary storage spring. The secondary storage spring can provide additional needle retraction force and can allow additional tuning of the force profile.

[0254] Many users wish to minimize the amount of material they discard (as trash). Moving the needle 156 to the rear of the applicator after deployment allows for easy access and removal of the needle 156 after deployment.

[0255] FIG. 20 illustrates a perspective view of the needle 156, needle hub 162, and spring 234 immediately after they have been proximally removed from the hole 238 in the proximal end of the first portion 150 of the nested assembly 132.

[0256] Aperture 238 is an opening at the proximal end of the applicator. Aperture 238 is configured to allow removal of needle 156, needle hub 162, and / or spring 234. This opening can be covered by a removable cover (e.g., a sticker, a hinged lid).

[0257] 21 and 22 illustrate perspective views when a removable cover 272 is coupled to first portion 150 to cover hole 238 through which needle 156 can be removed from nested assembly 132. A hinge 274 can couple cover 272 to first portion 150 such that cover 272 can rotate to close hole 238 (as shown in FIG. 22) and open hole 238 (as shown in FIG. 21).

[0258] Removing the cover 272 may allow the user to remove the needle 156 from the applicator (e.g., the nesting assembly 132) so that the user can place the needle 156 in a sharps disposal container and reuse the applicator with a new needle. Removing the needle 156 from the applicator may also allow the remaining applicator to be placed in a general waste collection system, reducing the amount of trash that needs to be held by the sharps disposal container.

[0259] The features described in the context of Figures 20-22 and 60 may be combined with any of the embodiments described herein.

[0260] 60 illustrates a perspective view of another nestable assembly embodiment 132h. A cover 272h is adhered to the proximal end of the nestable assembly 132h and covers an aperture configured to remove the needle after storing the needle (as described in the context of FIGS. 21 and 22). Peeling the cover 272h from the nestable assembly 132h can allow a user to discard the needle 156 (shown in FIG. 7) into a sharps disposal container.

[0261] In this embodiment, cover 272h is a flexible film, such as a Tyvek label manufactured by EI du Pont de Nemours and Company ("DuPont"). Cover 272h can include an adhesive for adhering cover 272h to the proximal end of nestable assembly 132h.

[0262] In some embodiments, the second cover 272 is adhered to the distal end of the nested assembly 132h and covers the end of the nested assembly 132h through which the sensor 138 (shown in FIG. 7) passes. The distal end of the nested assembly 132h can also be covered by a plastic cap 122h.

[0263] The cover 272h can be configured to allow a sterilization process to pass through the material of the cover 272h to facilitate sterilization of the interior of the nestable assembly 132h. For example, a sterilizing gas can be passed through the cover 272h.

[0264] Any of the features described in the context of Figure 60 may be applied to all aspects and embodiments identified herein. For example, an embodiment described in the context of Figure 60 may be combined with an embodiment described in the context of Figures 1-59 and 61-70.

[0265] Nested assembly 132h can use the same internal features and components as described in the context of Figure 7. One important difference is that first portion 150h slides over the exterior surface of second portion 152 (rather than sliding over an interior portion of second portion 152 as shown in Figure 7). Also, nested assembly 132h does not use a sterile barrier shell 120 (as shown in Figure 2).

[0266] Any of the features described in the context of Figures 7-22 may be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of Figures 7-22 may be combined with the embodiments described in the context of Figures 23-70. Furthermore, any of the features of an embodiment may be combined, partially or wholly, independently with other embodiments described herein, e.g., one, two, or more embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0267] Force Profile 7, in some embodiments, moving the first portion 150 of the nestable assembly 132 distally relative to the second portion 152 typically involves placing a distal end of the system against the recipient's skin and then applying a distal force to the proximal end of the system that moves the first portion 150 distally relative to the second portion 152 to deploy the needle 156 and / or glucose sensor 138 into the skin.

[0268] The optimal user force generated axially in the direction of deployment is a balance between preventing accidental premature deployment and ease of insertion. The ideal force at a particular portion of the distal actuation may be much less than ideal at another portion of the distal actuation.

[0269] A user places an applicator (e.g., nesting assembly 132) against the skin surface and applies a distal force to the applicator (e.g., by pressing down on the proximal end of the applicator). When the user-generated force exceeds a threshold, the applicator is compressed (e.g., telescoping distally) and the user drives the sensor into the body.

[0270] Some embodiments include unique force profiles that reduce accidental premature deployment, dramatically increase the likelihood of full and proper deployment, and reduce patient discomfort. Certain structures enable these unique force profiles. For example, the following structures can enable the unique force profiles described herein: structures that hold the nested assembly 132 in a proximal start position, structures that attach the sensor module 134 to the base 128, structures that release the sensor module 134 from the first portion 150, structures that prevent premature retraction of the needle 156, structures that retract the needle 156, structures that release the base 128 from the second portion 152, structures that absorb bumps at a distal position, and structures that hold the nested assembly 132 in a distal end position. These structures are described in various sections herein.

[0271] Some embodiments include a system for applying an on-skin sensor assembly 600 to a recipient's skin 130 (shown in FIG. 4). Referring now to FIG. 7, the system can include a nestable assembly 132 having a first portion 150 configured to move distally relative to a second portion 152 along a path 154 from a proximal start position to a distal position, a glucose sensor 138 coupled to the first portion 150, and a latch 236 configurable to prevent the needle 156 from moving proximally relative to the first portion.

[0272] First portion 150 is releasably secured in a proximal start position by a securing mechanism (e.g., the combination of 240 and 242 in FIG. 7 ) that prevents first portion 150 from moving distally relative to second portion 152. The system is configured such that moving first portion 150 distally relative to second portion 152, prior to and / or by reaching the distal position, releases latch 236, thereby causing needle 156 to retract proximally into the system.

[0273] In some embodiments, the locking mechanism is formed by an interference between the first portion 150 and the second portion 152. The interference can be configured to prevent the first portion 150 from moving distally relative to the second portion 152. For example, the radially outer protrusion 240 of the first portion 150 can impinge on the proximal end 242 of the second portion 152 such that moving the first portion 150 distally requires overcoming a threshold force to deform the first portion 150 and / or the second portion 152 to allow the radially outer protrusion 240 to move distally relative to the proximal end 242 of the second portion 152.

[0274] The system can include a first force profile measured along the path 154. As shown in Figure 23, the force profile 244 can include force on the Y-axis and distance traveled on the X-axis. With reference now to Figures 7 and 23, the force profile 244 can be measured along the central axis 196.

[0275] One way that the force profile 244 can be measured is to place the Nested assembly 132 against the skin, place a force gauge, such as a load cell, at the proximal end of the Nested assembly 132, calibrate the measurement system to compensate for the weight of the force gauge, and then press on the proximal side of the force gauge to drive the Nested assembly 132 from a proximal start position to a distal position along the path 154. Figure 23 illustrates the relationship between force and distance from the proximal start position based on this type of testing procedure.

[0276] The first force profile 244 can comprise a first magnitude 246 corresponding to overcoming the locking mechanism (e.g., 240 and 242), a third magnitude 250 corresponding to releasing the latch 236 (e.g., releasing the needle retraction mechanism), and a second magnitude 248 corresponding to an intermediate portion of the pathway 154 that is distal to overcoming the locking mechanism and proximal to releasing the latch 236.

[0277] In some embodiments, the second magnitude 248 is the peak force associated with compressing the needle retraction spring (e.g., spring 234 in FIG. 7) before beginning to release the latch 236. This peak force can be at least 0.5 pounds, at least 1.5 pounds, less than 4 pounds, and / or less than 6 pounds.

[0278] In some embodiments, the third magnitude 250 is the peak force associated with releasing the needle retraction mechanism. This peak force can be at least 1 pound, at least 2 pounds, less than 4 pounds, and / or less than 6 pounds.

[0279] In some embodiments, the second magnitude 248 is less than the first magnitude 246 and the third magnitude 250 such that the system is configured to facilitate needle acceleration during an intermediate portion of the path 154 to allow for adequate needle velocity when the needle 156 (or glucose sensor 138) initially pierces the skin.

[0280] The first magnitude 246 can be the peak force required to overcome the securing mechanism (e.g., 240 and 242). This peak force can be at least 5 pounds, at least 6 pounds, less than 10 pounds, and / or less than 12 pounds. The first magnitude 246 can be at least 100 percent greater than the second magnitude 248. The first magnitude 246 can be at least 200 percent greater than the second magnitude 248. The second magnitude 248 can be during a portion of the force profile 244 where the compression of the spring 234 is at least 50 percent of the maximum spring compression reached just before the needle 156 begins to retract proximally. The slope of the force profile 244 can be positive for at least 1 millimeter during the time the second magnitude 248 is measured (due to the increasing spring force as the spring compression increases).

[0281] The first magnitude 246 can be greater than the third magnitude 250 (and / or greater than the second magnitude 248) such that the system is configured to prevent the initiation of a glucose sensor insertion cycle unless a user applies sufficient force to release the latch 236. For example, the force required to move the projection 240 distally relative to the proximal end 242 can be purposefully designed to be greater than the force required to retract the needle 156.

[0282] To provide an adequate safety margin, the first magnitude 246 can be at least 50 percent greater than the third magnitude 250. In some embodiments, the first magnitude 246 can be at least 75 percent greater than the third magnitude 250. To avoid the system from making the first magnitude 246 higher than necessary given the force required against the first magnitude 246 along the path 154, the first magnitude 246 can be less than 250 percent greater than the third magnitude 250.

[0283] The second force profile 252 can correspond to an intermediate portion of the path 154. For example, the second magnitude 248 can be part of the second force profile 252. This second force profile 252 can include a period during which the slope is positive (due to the increasing spring force as the spring compression increases) for at least 1 millimeter, at least 2.5 millimeters, less than 8 millimeters, and / or less than 15 millimeters.

[0284] In response to compressing spring 234 configured to enable the system to retract needle 156 into nested assembly 132, the proximal millimeters of second force profile 252 have a lower average force than the distal millimeters of second force profile 252.

[0285] The system also includes a first force profile 254 (measured along path 154). The first force profile 254 comprises a first average magnitude corresponding to moving distally past the proximal half of the fixation mechanism and a second average magnitude corresponding to moving distally past the distal half of the fixation mechanism. The first average magnitude is greater than the second average magnitude such that the system is configured to prevent the system from initiating a sensor insertion cycle unless the user applies sufficient force to complete the sensor insertion cycle.

[0286] The first force peak 256 coincides with moving distally past the proximal half of the fixation mechanism. The first force peak 256 is at least 25 percent higher than the second average magnitude.

[0287] The first force profile 254 comprises a first magnitude 246 consistent with overcoming the fixation mechanism and a subsequent magnitude consistent with stopping the fixation mechanism (e.g., moving past a distal portion of the fixation mechanism). The first magnitude 246 comprises a proximal vector and the subsequent magnitude comprises a distal vector. FIG. 23 is truncated at zero force so in FIG. 23 the distal vector appears to have a magnitude of zero, although the actual value is negative (e.g., negative 2 pounds).

[0288] The proximal vector means that the system is resisting distal movement of the first portion 150 relative to the second portion 152. The distal vector means that the second half of the fixation mechanism can assist in propelling the needle 156 and / or sensor 138 towards and / or into the skin. In other words, the distal vector assists distal movement of the first portion 150 relative to the second portion 152.

[0289] The third force profile 260 can include multiple peaks due to the following events: docking of the sensor module 134 to the base 128, removal of the base from the second part 152 (and thus removal from the nested assembly 132), inward disengagement of the release feature 160 of the needle hub 162 by the proximal protrusion 170 of the second part 152, release of the latch 236, retraction of the needle 156 into the internal chamber of the first part 150, and / or impact of the first part 150 against a distal position (e.g., end of stroke).

[0290] 7, the fixation mechanism can be a radially outer protrusion 240 (of the first portion 150) configured to collide with a proximal end 242 of the second portion 152 such that moving the first portion 150 distally overcomes a force threshold and deforms the first portion 150 and / or the second portion 152, allowing the radially outer protrusion 240 to move distally relative to the proximal end 242 of the second portion 152. The radially outer protrusion 240 is configured to deform the second portion 152 into an elliptical shape, allowing the first portion 150 to move distally relative to the second portion 152.

[0291] 24 illustrates another fixation mechanism. At least a section of the first portion 150 interferes with the proximal end 242 of the second portion 152 such that pushing the first portion 150 distally relative to the second portion 152 requires a force greater than a force threshold. The force threshold is the minimum force required to deform at least one of the first portion 150 and the second portion 152 to overcome an interference 266, shown inside the dashed circle in FIG. 24.

[0292] In various embodiments, many different interference geometries and types are used. The interference can be between the first portion 150 and the second portion 152. The interference can be between the needle hub 162 and the second portion 152. For example, the interference can resist distal movement of the needle hub 162.

[0293] In some embodiments, first portion 150 includes a tapered portion 262. Once the interference section of first portion 150 has moved distally past interference region 266, tapered portion 262 transitions the system to a state where interference portion 266 no longer impedes distal movement of first portion 150.

[0294] The second portion 152 can also have a taper 263. The taper 263 can be on an inner surface of the second portion 152 such that it has a larger interior size when measured from proximal to distal along the taper 263.

[0295] The interfering portion 242 of the second portion 152 may include a ramp portion (as shown in FIG. 24) to aid in the deformation described above. The interfering section of the first portion 150 is positioned proximally relative to the interfering section of the second portion 152.

[0296] The fixation mechanism can include a radially outer protrusion (e.g., 240 in FIG. 7 ) of the first portion 150 that interferes with a radially inner protrusion of the second portion 152 (e.g., as shown by interference portion 266 in FIG. 24 ) such that the fixation mechanism is configured to deform the second portion 152 into an elliptical shape, thereby allowing the first portion 150 to move distally relative to the second portion 152.

[0297] Any of the features described in the context of Figures 24-32 may be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of Figures 24-32 may be combined with the embodiments described in the context of Figures 1-23 and Figures 33-70. Furthermore, any of the features of an embodiment may be combined, partially or wholly, independently with other embodiments described herein, e.g., one, two, or more than two embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0298] 25 illustrates a cross-sectional view of a portion of one embodiment in which a needle holder (e.g., needle hub 162) is configured to resist distal movement of the first portion 150 relative to the second portion 152b. The second portion 152b is similar to the other second portions 150 (e.g., as shown in FIG. 7), except that the second portion 152b includes a flex arm 276 that is at least part of a securing mechanism. The flex arm 276 releasably couples to the needle holder to releasably secure the first portion 150 to the second portion 152b in a proximal start position (as shown in FIG. 7).

[0299] Needle 156 (shown in FIG. 7) is retractably coupled to first portion 150 by needle holder 162. Needle holder 162 is configured to resist distal movement of first portion 150 relative to second portion 152b by a chamfer and / or ramp 278 that interferes with flex arms 276. Pushing first portion 150 distally requires overcoming the force required to deflect flex arms 276 outward such that flex arms 276 move away from ramp 278.

[0300] FIG. 27 illustrates a perspective view of another fastening mechanism, frangible release 280. FIG. 26 illustrates a top view of frangible ring 282. Ring 282 includes two frangible tabs 284 that protrude radially inward. In some embodiments, tabs 284 protrude radially inward on either side of ring 282 relative to one another. The frangible member (e.g., ring 282) can be part of first portion 150, part of second portion 152, or any other part of the system. For example, the frangible member can be a feature of molded second portion 152.

[0301] Ring 282 can be made of a frangible material configured to allow tab 284 to break when first portion 150 is pushed distally relative to second portion 152. For example, a section of first portion 150 can be positioned proximally over tab 284 when first portion 150 is in a proximal start position (as shown in FIG. 27 by frangible release 280). Moving first portion 150 distally causes the section of first portion 150 to bend and / or break tab 284.

[0302] In some embodiments, the radially outward projection 286 of the first portion 150 is configured to bend and / or break the tab 284. The ring 282, tab 284, and other components described herein can be molded from plastics such as acrylonitrile butadiene styrene, polyethylene, and polyetheretherketone. (The springs, interconnects, and needles can be made of steel.) In some embodiments, the ring 282 is at least 0.2 millimeters thick, at least 0.3 millimeters thick, less than 0.9 millimeters thick, or less than 1.5 millimeters thick.

[0303] The ring 282 can be secured between the first portion 150 and the second portion 152 of the nested assembly 132. The ring 282 can be wrapped around the circumference of the first portion 150 and can be positioned proximally relative to the second portion 152 such that the ring 282 rests on a proximal end of the second portion 152.

[0304] Ring 282 allows for a frangible bond between first portion 150 and second portion 152 while first portion 150 is in a proximal starting position. In FIG. 27, the system is configured such that moving first portion 150 to a distal position breaks the frangible bond (e.g., frangible release 280).

[0305] In some embodiments, the tab 284 is not part of the ring 282. The tab 284 can be part of the second portion 152 or part of the first portion 150.

[0306] 27 also includes a magnet system 290. The magnet system 290 includes a magnet and a metal element (e.g., a metal disk) in sufficient proximity such that the magnet is attracted to the metal element. For example, the second portion 152 can include a magnet and the first portion 150 can include a metal element. In some embodiments, the second portion 152 can include a metal element and the first portion 150 can include a magnet.

[0307] The magnets and metal elements can be positioned such that they are positioned along a straight line oriented radially outward from the central axis 196 (shown in FIG. 7 ). This configuration can position the magnets to sufficiently attract the metal elements to resist movement of the first portion 150. For example, when the first portion 150 is in the proximal start position, the magnetic force of the magnet system 290 can resist distal movement of the first portion. Thus, the magnets releasably couple the first portion 150 to the second portion 152 while the first portion 150 is in the proximal start position.

[0308] In some embodiments, the user can compress the internal spring, or the spring can be pre-compressed (e.g., fully compressed at the factory). The nesting assembly can include a button 291 configured to release the spring force and move the needle and / or sensor into the skin.

[0309] The cover 272h, illustrated in the context of Figure 60, can be adhered to the proximal end of the first portion 150 shown in Figure 27. The cover 272h can be used with any of the embodiments described herein.

[0310] FIG. 31 illustrates a side view of the nesting assembly 132e having a first portion 150e and a second portion 152e. The first portion 150e includes a radially outer protrusion 286e configured to engage a radially inner ramp 296 positioned on an inner wall of the second portion 152e. When a user applies a distal axial force to the first portion 150e, the protrusion 286e impacts the ramp 296. The angle of the ramp causes the first portion 150e to rotate relative to the second portion 152e. This rotation resists the distal force and also acts as a locking mechanism. Once the protrusion 286e moves beyond the distal end of the ramp 296, the ramp 296 no longer rotates and therefore no longer acts as a locking mechanism.

[0311] Many of the embodiments described herein rely on a person's compressive force. A number of unique structures enable the force profiles described herein. The structures help ensure that the compressive force created by a person pushing distally on a portion of the system results in reliable performance. One challenge with relying on people to push down on the system to generate the appropriate force is that the input force can vary significantly from user to user. Even a single user may apply different input forces at different times.

[0312] One solution to this variability is to replace the need for a user-generated input force with a motor-generated force. Motors can provide a reliable input force. Motors also allow for the force to be varied at different segments of the path from a proximal starting position to a distal position.

[0313] 28-30 illustrate an embodiment of the nested assembly 132c, 132d including a motor 290c, 290d to drive the needle 156 and / or glucose sensor 138 into the skin. The motor 290c, 290d can be a linear actuator that uses an internal magnetic system to push a rod distally and proximally. The linear actuator can also convert a rotational input into linear motion to push the rod distally and proximally. The movement of the rod can move various parts of the system including the needle 156, the needle hub 162c, the first portion 150c, 150d of the nested assembly 132c, 132d, the nested assembly 132c, 132d, the sensor module 134, and / or the sensor 138. The motor 290c, 290d can include an internal battery to provide electricity to the motor 290c, 290d.

[0314] 28 illustrates a perspective cross-sectional view of an embodiment in which the motor 290c pushes the needle hub 162c distally relative to the motor 290c and relative to the second portion 152c. The needle hub 162c may include a rod that slides in and out of a housing of the motor 292c. Distal movement of the needle hub 162c may push at least a portion of the needle 156 and / or the sensor 138 (shown in FIG. 7) into the skin. Distal movement of the needle hub 162c may move the sensor module 134 distally such that the sensor module 134 docks with the base 128. This coupling may precede removal of the base 128 from the nested assembly 132c.

[0315] 29 and 30 illustrate side cross-sectional views of another motor embodiment. In this embodiment, the rod 294 of the motor 292d is coupled to and immovable relative to the second portion 152d of the nested assembly 132d. The motor 292d is coupled to and immovable relative to the first portion 150d of the nested assembly 132d. As a result, retracting the rod 294 into the housing of the motor 292d moves the first portion 150d distally relative to the second portion 152d. The glucose module 134 is coupled to the distal portion of the first portion 150d (as described herein). Thus, the glucose sensor 138 moves distally into the recipient's skin and the glucose module 134 is coupled to the base 128. As illustrated in FIGS. 29 and 30, the embodiment does not include a needle. Similar embodiments may include a needle.

[0316] 32 illustrates a perspective cross-sectional view of the nested assembly 132. In some embodiments, a protrusion 302 of the first portion 150 mates with a hole 304 of the second portion 152. The protrusion 302 can be oriented distally to latch into engagement with the hole 304 in response to the first portion 150 reaching a distal position.

[0317] In some embodiments, the protrusion 302 of the second portion 152 mates with the hole 304 of the first portion 150. The protrusion 302 can be oriented proximally to latch into engagement with the hole 304 in response to the first portion 150 reaching a distal position.

[0318] The protrusion 302 can be a flex arm that is at least 10 millimeters, at least 15 millimeters long, and / or less than 50 millimeters long. The protrusion 302 can include an end portion that protrudes at an angle relative to a central axis of the majority of the protrusion 302. The angle can be at least 45 degrees, at least 75 degrees, less than 110 degrees, or less than 135 degrees.

[0319] Binding protrusion 302 to hole 304 can permanently lock first portion 150 in a downward position (distal of the proximal start position and within 3 millimeters of the distal position) while needle 156 is in the retracted state. This locking can prevent the system from being reused and can prevent needle stick injuries.

[0320] Any of the features described in the context of FIG. 23 may be applied to all aspects and embodiments identified herein. For example, the embodiment described in the context of FIG. 23 may be combined with the embodiments described in the context of FIGS. 1-22 and 24-70. Furthermore, any of the features of an embodiment may be combined, partially or wholly, independently with other embodiments described herein, e.g., one, two, or more than two embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0321] Interconnects 4, in many embodiments, the electronics unit 500 drives a voltage bias through the sensor 138 so that the current can be measured. Thus, the system can analyze the recipient's glucose level. The reliability of the electrical connection between the sensor 138 and the electronics unit 500 is critical for accurate sensor data measurement.

[0322] In many embodiments, the recipient or caregiver makes the electrical connection between the sensor 138 and the electronics unit 500. The seal 192 can prevent fluid ingress when the electronics unit 500 is pressed onto the glucose sensor module 134. Oxidation and corrosion can change the electrical resistance of the system and are a source of error and noise in the signal.

[0323] The electrical connections must be mechanically stable: relative motion between parts of the electrical system can cause signal noise that can interfere with obtaining accurate glucose data.

[0324] A lower resistance electrical connection is more power efficient, which can help maximize the battery life of the electronics unit 500.

[0325] In embodiments where the recipient or caregiver must compress the electrical interconnects and / or seal 192, minimizing the required force increases user satisfaction. Less force applied by the user makes the transmitter easier to install. If the force required is too great, users and caregivers may inadvertently fail to apply enough force, which can compromise system reliability and performance. The force that a user must apply to couple the electronics unit 500 to the base 128 and sensor module 134 is strongly influenced by the force required to compress the interconnects. Thus, a need exists for electrical interconnects that have a smaller compressive force.

[0326] Manufacturing variations, recipient movement, and temperature fluctuations while the recipient is using the on-skin sensor assembly 600 are necessary to provide a robust electrical connection throughout the active compression range (encompassing the minimum and maximum compression states reasonably possible). Thus, a need exists for an electrical connection that is tolerant to compression variations within the active compression range.

[0327] A metallic spring (e.g., a coil spring or a leaf spring) can be compressed between the sensor 138 and the electronics unit 500 to provide a strong and reliable electrical connection that requires less compressive force to couple the electronics unit 500 to the base 128.

[0328] 33 illustrates a perspective view of the on-skin senor assembly just before the electronics unit 500 (e.g., transmitter) is snapped to the base 128. Mating the electronics unit 500 to the base 128 can compress the seal 192 to prevent fluid ingress and can also compress the interconnect (e.g., spring 306) to create the electrical connection 310 between the glucose sensor 138 and the electronics unit 500.

[0329] Making the electrical connection 310 and / or coupling the electronics unit 500 to the base 128 can wake the electronics unit 500 (e.g., a transmitter) from a sleep mode. For example, a conductive member (e.g., of the sensor module 134 and / or the base 128) can contact an electrical contact of the electronics unit 500 (e.g., an electrical contact of a battery of the electronics unit 500), which can wake the electronics unit 500 from a sleep mode. The conductive member of the sensor module 134 and / or the base 128 can be a battery jumper that closes a circuit and allows electricity to flow from the battery to other parts of the electronics unit 500.

[0330] Thus, making the electrical connection 310 and / or coupling the electronics unit 500 to the base 128 "activates" the electronics unit 500, enabling and / or preparing the electronics unit 500 to wirelessly transmit information to other devices 110-113 (shown in FIG. 1). U.S. Patent Application Publication No. US2012 / 0078071(A1) contains additional information regarding transmitter activation. The entire contents of U.S. Patent Application Publication No. US2012 / 0078071(A1) are incorporated herein by reference.

[0331] The distal face of the electronics unit 500 may include a planar electrical contact that contacts the proximal end portion of the spring 306. The distal end portion of the spring 306 may contact various conductive elements of the glucose sensor 138. Thus, the spring 306 may electrically couple the electronics unit 500 to the various conductive elements of the glucose sensor 138. In the illustrated embodiment, two metallic springs 306 electrically connect the glucose sensor 138 and the electronics unit 500. Some embodiments use one spring 306. Other embodiments use three, four, five, ten, or more springs 306.

[0332] A metallic spring 306 (e.g., a gold plated spring) is disposed above the sensor wire 138 in the sensor module 134. The sensor 138 is positioned between the rigid polymer base 128 and the bottom surface of the spring 306. The top surface of the spring 306 contacts a palladium electrode located on the bottom of the electronics module 500. The rigid electronics module 500 and rigid polymer base 128 together create a compression sandwich with the sensor 138 and the spring 306.

[0333] The springs 306 are oriented such that their central axes are within 25 degrees of the central axis 196 (shown in FIG. 7) of the nested assembly 132. The springs 306 may have a helical shape. The springs 306 may be coil springs or leaf springs.

[0334] The spring 306 can have ends that are flat, ground, square, ground square, or any other suitable configuration. Gold, copper, titanium, and bronze can be used to make the spring 306. The spring 306 can be made from spring steel. In some embodiments, the steel used to make the spring 306 can be low alloy medium or high carbon steel with very high yield strength. The spring 306 can be a compression spring, a torsion spring, a constant spring, a variable spring, a helical spring, a flat spring, a machined spring, a cantilever spring, a bar spring, a counterbalance spring, a leaf spring, a V-shaped spring, and / or a washer spring.

[0335] Some embodiments use a spring-loaded pin system. The spring system can include a receptacle. The pin can be positioned partially inside the receptacle such that the pin can slide partially in and out of the receptacle. The spring can be positioned inside the receptacle such that the spring biases the pin outwardly toward the electronics unit 500. The receptacle can be electrically coupled to the sensor 138 such that pressing the electronics unit 500 against the spring-loaded pin system electrically couples the electronics unit 500 and the sensor 138.

[0336] Mill-Max Mfg. Corp. ("Mill-Max") of Oyster Bay, New York, USA manufactures spring-loaded pin systems with nickel-gold plated brass alloy shells. One Mill-Max spring-loaded pin system has a stainless steel spring and order code 0926-1-15-20-75-14-11-0.

[0337] In some embodiments, the electronics unit 500 includes a battery to provide power to various electrical components of the electronics unit 500 (eg, the transmitter).

[0338] In some embodiments, the base 128 can include a battery 314 positioned outside the electronics unit 500. The battery 314 can be electrically coupled to the electrical connections 310 such that coupling the electronics unit 500 to the base 128 couples the battery 314 to the electronics unit 500. Figures 22B and 22C of US Patent Application Publication No. US2009 / 0076360(A1) illustrate a battery 444 that, in some embodiments, can be part of the base (which can have a number of forms including that of the base 128 shown in Figure 33 herein). The entire contents of US Patent Application Publication No. US2009 / 0076360(A1) are incorporated herein by reference.

[0339] 34 illustrates a perspective view of the sensor module 134. The protrusions 308 can secure the springs 306 to the sensor module 134. (To make FIG. 34 more clear, not all of the protrusions 308 are labeled.) The protrusions 308 can protrude distally.

[0340] At least three, at least four, and / or fewer than ten protrusions 308 can be configured to contact the outer periphery of the spring 306. The protrusions 308 can be separated by gaps. The gaps allow the protrusions 308 to flex outward as the spring 306 is inserted between the protrusions 308. A downward force coupling the electronics unit 500 to the base 128 can push the spring 306 against the sensor 138, electrically coupling the spring 306 to the sensor 138. The sensor 138 can extend between at least two of the protrusions 308.

[0341] FIG 33 illustrates an on-skin sensor system 600 configured for transcutaneous glucose monitoring of a recipient. The on-skin sensor system 600 may be used with the other components shown in FIG 7. The sensor module 134 may be replaced with the sensor modules 134d, 134e shown in FIG 35 and FIG 37. Thus, the sensor modules 134d, 134e shown in FIG 35 and FIG 37 may be used with the other components shown in FIG 7.

[0342] 33 and 34, a system 600 can include a sensor module housing 312, glucose sensors 138a, 138b having a first section 138a configured for subcutaneous sensing and a second section 138b mechanically coupled to the sensor module housing 312, and an electrical interconnect (e.g., spring 306) mechanically coupled to the sensor module housing 312 and electrically coupled to the glucose sensors 138a, 138b. The spring can be a conical spring, a helical spring, or any other type of spring described herein or suitable for electrical connection.

[0343] The sensor module housing 312 includes at least two proximal protrusions 308 positioned around the circumference of the spring 306. The proximal protrusions 308 are configured to assist in orienting the spring 306. A segment of the glucose sensor 138b is positioned between the proximal protrusions 308 (distal to the spring 306).

[0344] The sensor module housing 312 is mechanically coupled to the base 128. The base 128 includes an adhesive 126 configured to couple the base 128 to the skin of a recipient.

[0345] The proximal protrusion 308 orients the spring 306 such that coupling the electronics unit 500 to the base 128 presses the spring 306 against a first electrical contact of the electronics unit 500 and a second electrical contact of the glucose sensor 138b, electrically coupling the glucose sensors 138a, 138b to the electronics unit 500.

[0346] 33 and 35-38, the system 600 may include a sensor module housing 312d, 312e, a glucose sensor 138a, 138b having a first section 138a configured for subcutaneous sensing and a second section 138b mechanically coupled to the sensor module housing 312d, 312e, and an electrical interconnect (e.g., leaf springs 306d, 306e) mechanically coupled to the sensor module housing 312d, 312e and electrically coupled to the glucose sensor 138a, 138b. The sensor modules 134d, 134e may be used in place of the sensor module 134 shown in FIG. 7. The leaf springs 306d, 306e may be configured to bend in response to the electronics unit 500 mating with the base 128.

[0347] As used herein, a cantilever spring is a type of leaf spring. As used herein, a leaf spring can be made of several strips of curved metal held together one above the other. As used herein in many embodiments, a leaf spring includes only one strip (e.g., one layer) of curved metal (rather than multiple layers of curved metal). For example, leaf spring 306d in FIG. 35 can be made of one layer of metal or multiple layers of metal. In some embodiments, a leaf spring includes one layer of flat metal on one end (such that the leaf spring is a cantilever spring).

[0348] 35 and 36, the sensor module housing 312d includes a proximal protrusion 320d having a channel 322d in which at least a portion of the second section of the glucose sensor 138b is positioned. The channel 322d positions a first region of the glucose sensor 138b such that the region is electrically coupled to the leaf spring 306d.

[0349] As shown in the cross-sectional perspective view of FIG. 36, the leaf spring 306d arcs away from the first region and protrudes proximally to electrically couple to the electronics unit 500 (shown in FIG. 33). At least a portion of the leaf spring 306d forms a "W" shape. At least a portion of the leaf spring 306d forms a "C" shape. The leaf spring 306d bends around the proximal protrusion 320d. The leaf spring 306d protrudes proximally to electrically couple to the electronics unit 500 (shown in FIG. 33). The seal 192 is configured to prevent ingress of fluid to the leaf spring 306d.

[0350] The leaf spring 306d is oriented such that coupling the electronics unit 500 to the base 128 (shown in FIG. 33) presses the leaf spring 306d against a first electrical contact of the electronics unit 500 and a second electrical contact of the glucose sensor 138b, electrically coupling the glucose sensors 138a, 138b to the electronics unit 500. The proximal height of the encapsulant 192 can be greater than the proximal height of the leaf spring 306d such that the electronics unit 500 contacts the encapsulant 192 before contacting the leaf spring 306d.

[0351] 33 and 37-38, the sensor module housing 312e includes a channel 322e in which at least a portion of the second section of the glucose sensor 138b is positioned. A distal portion of the leaf spring 306e is positioned within the channel 322e such that a proximal portion of the leaf spring 306e protrudes proximally from the channel 322e.

[0352] The sensor module housing 312e includes a groove 326e that traverses (e.g., intersects) the channel 322e. The leaf spring 306e includes a tab 328 positioned within the groove to prevent rotation of the leaf spring. At least a portion of the leaf spring 306e forms a "C" shape.

[0353] Figures 36 and 38 illustrate two leaf spring shapes. Other embodiments use other types of leaf springs. The elements shown in Figures 33-38 can be combined.

[0354] 33-38, the interconnects 306, 306d, 306e may include palladium contacts, alloys, clad materials, conductive plated materials, gold plated portions, silver materials, and / or any suitable conductor. The interconnects 306, 306d, 306e described herein may have a resistance of less than 5 ohms, less than 20 ohms, and / or less than 100 ohms. Many interconnect embodiments allow for a resistance of about 2.7 ohms or less, which may significantly extend battery life compared to higher resistance versions.

[0355] Reducing the force required to compress the interconnects 306, 306d, 306e (e.g., when the electronics unit 500 is coupled to the base 128) can reduce coupling errors and difficulties. For example, if the required force is high, the probability of inadvertently failing to couple the electronics unit 500 to the base 128 is quite high. In some instances, if the required force is too high, some users may not be able to couple the electronics unit 500 to the base 128. Thus, a need exists for a system that requires less force to couple the electronics unit 500 to the base 128.

[0356] Many of the embodiments described herein (e.g., spring embodiments) significantly reduce the force required to couple the electronics unit 500 to the base 128. The interconnects 306, 306d, 306e can have a compressive force of at least 0.05 pounds, less than 0.5 pounds, less than 1 pound, less than 3 pounds, and / or less than 4.5 pounds over the active compression range.

[0357] In some embodiments, the interconnects 306, 306d, 306e may require less than 1 pound of compression force to compress the springs 20 percent from the relaxed position, which is a substantially uncompressed position. In some embodiments, the interconnects 306, 306d, 306e may require less than 1 pound of compression force to compress the springs 25 percent from the relaxed position, which is a substantially uncompressed position. In some embodiments, the interconnects 306, 306d, 306e may require less than 1 pound of compression force to compress the springs 30 percent from the relaxed position, which is a substantially uncompressed position. In some embodiments, the interconnects 306, 306d, 306e (modifying dependency on independent claims) may require less than 1 pound of compression force to compress the springs 50 percent from the relaxed position, which is a substantially uncompressed position.

[0358] The springs 306, 306d, 306e can have a height of 2.6 millimeters, at least 0.5 millimeters, and / or less than 4 millimeters. The seal 192 has a height of 2.0 millimeters, at least 1 millimeter, and / or less than 3 millimeters. In some embodiments, the springs 306, 306d, 306e in their relaxed (i.e., substantially uncompressed) state protrude at least 0.2 millimeters and / or less than 1.2 millimeters from the top of the seal 192 (e.g., distally).

[0359] When the electronics unit 500 is coupled to the base 128, the compression of the springs 306, 306d, 306e can be 0.62 millimeters, at least 0.2 millimeters, less than 1 millimeter, and / or less than 2 millimeters, with percent compression of 24 percent, at least 10 percent, and / or less than 50 percent. The active compression range of the springs 306, 306d, 306e can be 16-40 percent, 8-32 percent, 40-57 percent, 29-47 percent, at least 5 percent, at least 10 percent, and / or less than 66 percent.

[0360] In some embodiments, the electrical connection between the sensor 138 and the electronics unit 500 is made at the factory. This electrical connection can be sealed at the factory to prevent fluid ingress, which may compromise the integrity of the electrical connection.

[0361] The electrical connections can be made via any of the following techniques: electrodes can be pierced into the conductive elastomer (so that no vertical deformation is required), the sensor can be "sandwiched" (e.g., compressed) between adjacent coils of a coil spring, conductive epoxy, brazing, laser welding, and resistance welding.

[0362] 4, 6, 7, and 33, one key electrical connection is between the electronics unit 500 (e.g., transmitter) and the sensor module 134. Another key electrical connection is between the sensor module 134 and the glucose sensor 138. Both connections must be strong to allow the sensor module 134 to be connected to the base 128, and then the base 128 and the sensor module 134 to the electronics unit 500 (e.g., transmitter). A stable sensor module 134 allows the sensor module 134 to be coupled to the base 128 without introducing signal noise in the future.

[0363] These two key electrical connections can be made at the factory (e.g., before the recipient or caregiver receives the system), or they can be made by the recipient or caregiver when the user attaches the electronics unit 500 to the base 128 and / or sensor module 134.

[0364] In some embodiments, the connections between the glucose sensor 138 and the sensor module 134 can be made at a factory (e.g., before a recipient or caregiver receives the system), and then a user can couple the electronics unit 500 to the sensor module 134 and / or base 128. In some embodiments, the electronics unit 500 can be coupled to the sensor module 134 and / or base 128 at a factory (e.g., before a recipient or caregiver receives the system), and then a user can couple this assembly to the glucose sensor 138.

[0365] Any of the features described in the context of Figures 33-38 may be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of Figures 33-38 may be combined with the embodiments described in the context of Figures 1-32 and 39-70. Furthermore, any of the features of an embodiment may be combined, partially or wholly, independently with other embodiments described herein, e.g., one, two, or more embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0366] 33 below, the battery 314 may be located internal to the electronics unit 500 or may be part of the base 128. Maximizing the life of the battery 314 is important for a number of reasons. For example, the electronics unit 500 may be stored for months or even years before use. If the battery 413 is significantly depleted during this storage, the number of days that the recipient is able to use the electronics unit (e.g., to measure analytes) may be drastically reduced.

[0367] In some embodiments, the electronics unit 500 is in a low power consumption state (e.g., a "sleep" mode) during storage (e.g., before receipt by a recipient). This low power consumption state can drain the battery 314. Thus, a need exists for a system that reduces or even eliminates battery power consumption during storage and / or before the electronics unit 500 is coupled to the base 128.

[0368] 33, making the electrical connection 310 and / or coupling the electronics unit 500 to the base 128 can wake the electronics unit 500 (e.g., a transmitter) from a sleep mode. For example, a conductive member (e.g., of the sensor module 134 and / or the base 128) can contact an electrical contact (e.g., an electrical contact of the battery of the electronics unit 500) of the electronics unit 500, which can wake the electronics unit 500 from a sleep mode and / or begin to flow power from the battery. The conductive member of the sensor module 134 and / or the base 128 can be a battery jumper that closes a circuit and allows electricity to flow from the battery to other portions of the electronics unit 500.

[0369] Thus, making the electrical connection 310 and / or coupling the electronics unit 500 to the base 128 may "activate" the electronics unit 500, enabling and / or preparing the electronics unit 500 to wirelessly transmit information to other devices 110-113 (shown in FIG. 1). U.S. Patent Application Publication No. US2012 / 0078071(A1) contains additional information regarding activating the electronics unit 500 (e.g., activating a transmitter). The entire contents of U.S. Patent Application Publication No. US2012 / 0078071(A1) are incorporated herein by reference.

[0370] FIG. 65 illustrates a perspective view of a portion of the sensor module 134j. In FIG. 65, some items such as springs and sensors are hidden to clarify that the sensor module 134j can use any spring or sensor described herein. The sensor module 134j can use any of the springs 306, 306d, 306e, sensors 138, 138a, 138b, protrusions 308, channels 322d, 322e, and grooves 326e described herein (e.g., as shown in FIG. 34-FIG. 40). The sensor module 134j can be used in place of any other sensor module described herein. The sensor module 134j can be used in the embodiment described in the context of FIG. 7 and can be used with any of the nested assemblies described herein.

[0371] Fig. 66 illustrates a side cross-sectional view of the sensor module shown in Fig. 65. Referring now to Figs. 65-70, the sensor module 134j includes a conductive jumper 420f (e.g., a conductive connection that may include a metal). The conductive jumper 420f is configured to electrically couple two electrical contacts 428a, 428b of the electronics unit 500 (e.g., a transmitter) in response to coupling the electronics unit 500 to the sensor module 134j and / or the base 128.

[0372] The conductive jumper 420f can be positioned at least partially between two electrical connections 426 (e.g., springs 306, 306d, 306e shown in FIGS. 34-38). The conductive jumper 306f can include two springs 306f coupled by a conductive link 422f. A first spring 306f of the jumper 420f can be coupled to a first contact 428a, and a second spring 306f of the jumper 420f can be coupled to a second contact 428b, which can complete an electrical circuit to enable the battery to provide electricity to the electronics unit 500. The spring 306f can be a leaf spring, a coil spring, a conical spring, and / or any other suitable type of spring. In some embodiments, the spring 306f is a proximal protrusion coupled to the contacts 428a, 428b.

[0373] 66, the conductive link 422f can be arched such that the sensor 138b (shown in FIG. 34) passes under and / or through the arched portion of the conductive link 422f. In some embodiments, the conductive link 422f is oriented within ±35 degrees of perpendicular to the sensor 138b such that the conductive link 422f crosses over a portion of the sensor 138b positioned inside the encapsulation area (e.g., within the encapsulation 192).

[0374] Figure 67 illustrates a perspective view of a portion of sensor module 134k that is similar to sensor module 134j shown in Figures 65 and 66. Figure 68 illustrates a top view of sensor module 134k shown in Figure 67.

[0375] 67 and 68, the sensor module 134k includes a different type of conductive jumper 420g, which includes two helical springs 306g conductively coupled by a conductive link 422g. The conductive link 422g is configured to cross over or under the sensor 138b (shown in FIG. 34). As shown in FIG. 67 and 68, the spring 306g is a conical spring, although some embodiments do not use a conical spring. The spring 306g is configured to electrically couple two electrical contacts 428a, 428b of the electronics unit 500 to initiate the flow of electricity in the electronics unit 500. Thus, the conductive jumper 420g can "wake up" the electronics unit 500. The conductive jumper 420g can be used with any of the sensor modules described herein.

[0376] 69 and 70 illustrate perspective views of the electronics unit 500 immediately before the electronics unit 500 is coupled to the base 128. As shown in FIG. 70, the electronics unit 500 can have two electrical contacts 428a, 428b configured to be electrically coupled to the conductive jumpers 420f (shown in FIGS. 65 and 66), 420g (shown in FIGS. 67 and 68). The electronics unit 500 can also have two electrical contacts 428c, 428d configured to be electrically connected to the springs 306, 306d, 306e (shown in FIGS. 34-38) and / or any other type of electrical connection 426 between the sensor 138 (shown in FIG. 39) and the electronics unit 500.

[0377] Coupling the electronics unit 500 to the sensor module 134k and / or base 128 can electrically and / or mechanically couple the electrical contacts 428a, 428b to the conductive jumpers 420f (shown in FIG. 65), 420g (shown in FIG. 67).

[0378] Coupling the electronics unit 500 to the sensor module 134k and / or base 128 may electrically and / or mechanically couple the electrical contacts 428c, 428d to the springs 306, 306d, 306e (shown in Figures 34-38) and / or any other type of electrical connection 426 between the sensor 138 (shown in Figure 39) and the electronics unit 500 (e.g., as shown in Figure 67).

[0379] Any of the features described in the context of Figures 65-70 may be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of Figures 65-70 may be combined with the embodiments described in the context of Figures 1-64. Furthermore, any of the features of an embodiment may be combined, partially or wholly, independently with other embodiments described herein, e.g., one, two, or more embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0380] Needle angle and offset FIG 43 shows a front view of the "C-shaped" needle 156. FIG 42 illustrates a bottom view of the C-shaped needle 156. The needle 156 includes a channel 330. Section 138a (shown in FIG 34) of a glucose sensor 138 (labeled in FIG 7) configured for subcutaneous sensing can be placed in the channel 330 (as shown in FIG 40).

[0381] The needle 156 can guide the sensor 138 into the skin of the recipient. A distal portion of the sensor 138 can be positioned within the channel 330 of the needle 156. At some times, the distal end of the sensor 138 protrudes from the needle 156 and catches on the recipient's tissue as the sensor 138 and needle 156 are inserted into the recipient. As a result, the sensor 138 may become distorted and not be able to be inserted deep enough into the subcutaneous tissue. In other words, in some embodiments, the sensor wire must be placed within the channel 330 of the C-shaped needle 156 to be guided into the tissue and must be retained within the channel 330 during deployment.

[0382] The risk of the sensor 138 protruding from the channel 330 (and thereby preventing proper insertion into the recipient) can be significantly reduced by positioning the sensor 138 within the channel 330 of the needle 156 at a particular angle 338 (shown in FIG. 41) and offset 336 (shown in FIG. 40). Position B 334 in FIG. 42 illustrates the sensor protruding from the channel 330.

[0383] The angle 338 and offset 336 cause elastic deformation of the sensor 138 to create a force pushing the sensor 138 to the bottom of the channel 300 (as shown by location A 332 in FIG. 42 ), while avoiding the potentially detrimental effects of an improper angle 338 and offset 336. The angle 338 and offset 336 also cause plastic deformation of the sensor 138, helping to shape the sensor 138 in a way that minimizes the risk of the sensor 138 being pushed out of the channel 330 during insertion into the skin.

[0384] In some embodiments, the angle 338 and offset 336 shape a portion of the sensor 138 to optimize insertion performance. For example, the angle 338 can bend the sensor 138 before placing the portion of the sensor 138 into the channel 330 of the needle 156.

[0385] As illustrated in Figure 39, a portion of the glucose sensor 138b (also labeled in Figure 34) can be disposed in a distally-facing channel 342 (which in some embodiments is a tunnel), which can help orient the glucose sensor 138b toward the channel 330 of the needle 156 (shown in Figure 43).

[0386] 41, the glucose sensor 138 can include an angle 338 between a portion of the glucose sensor 138 coupled to the sensor module housing 312 (shown in FIG. 34) and a portion of the glucose sensor configured to be inserted into a recipient. In some embodiments, the angle 338 can be formed prior to coupling the sensor 138 to the sensor module housing 312 (shown in FIG. 34) and / or prior to placing a portion of the sensor 138 within the channel 330 of the needle 156 (shown in FIG. 43).

[0387] 41 below, an angle 338 that is less than 110 degrees may result in failed deployment (e.g., with an offset of 0.06 inches plus 0.06 inches and / or minus 0.03 inches). In some embodiments, an angle 338 that is less than 125 degrees may result in failed deployment (e.g., with an offset of 0.06 inches plus 0.06 inches and / or minus 0.03 inches). An angle 338 of 145 degrees (plus 5 degrees and / or minus 10 degrees) may reduce the chance of failed deployment. In some embodiments, the angle 338 is at least 120 degrees and / or less than 155 degrees.

[0388] In some embodiments, the manufacturing method includes bending the sensor 138 before placing a portion of the sensor 138 in the channel 330 of the needle 156. In this manufacturing method, the angle is measured from a central axis of the portion of the glucose sensor 138 coupled to the sensor module housing 312 (shown in FIG. 34) and the portion of the glucose sensor configured to be inserted into a recipient. According to this angle measurement, an angle of more than 70 degrees may result in failed deployment (e.g., due to an offset of 0.06 inches plus 0.06 inches and / or minus 0.03 inches). In some embodiments, an angle of more than 55 degrees may result in failed deployment (e.g., due to an offset of 0.06 inches plus 0.06 inches and / or minus 0.03 inches). An angle of 35 degrees (plus 10 degrees and / or minus 5 degrees) may reduce the chance of failed deployment. In some embodiments, the angle is at least 25 degrees and / or less than 60 degrees.

[0389] Too large an offset 336 (shown in FIG. 40) may result in the sensor 138 not being securely held in the channel 330 (shown in FIG. 42). In other words, a large offset 336 may result in the sensor 138 being positioned at position B 334 rather than securely at position A 332. Too small an offset 336 may exert too much stress on the sensor 138, destroying it. Taking these factors into consideration, in some embodiments, the offset 336 is at least 0.02 inches, at least 0.04 inches, less than 0.08 inches, or less than 0.13 inches. In some embodiments, the offset 336 is 0.06 inches or more and / or 0.10 inches or more. The offset 336 is measured from the base of the needle 156 as shown in FIG. 40.

[0390] In some embodiments, at least a portion of the bend of the sensor 138 can include strain relief. For example, the bend of the sensor 138 can be encapsulated in a polymer or elastomer tube to provide strain relief to the sensor 138. In some cases, the entire bend of the sensor 138 can be encapsulated in the polymer or elastomer tube. In some embodiments, the tube is constructed of a soft polymer. The polymer or elastomer tube can encapsulate the sensor 138 by a heat shrink process. In some embodiments, silicone gel can be applied to the sensor at or near the channel 342 (shown in FIG. 39) or along at least a portion of the underside of the proximal protrusion 320d (shown in FIG. 35).

[0391] The needle channel width 344 (shown in FIG. 42) can be 0.012 inches. In some embodiments, the width 344 is greater than or equal to 0.010 inches and / or less than or equal to 0.015 inches. The width 344 of the channel 330 is measured at the narrowest width in which the glucose sensor 138 can be positioned.

[0392] 40 , a funnel 182 in the base 128 can help guide the needle 156 and / or glucose sensor 138 into the hole 180. The funnel 182 and hole 180 can help secure the sensor 138 to the C-shaped needle 156 during storage and deployment. For example, the hole 180 can be small enough that there is no extra space (within the hole 180) for the sensor 138 to exit the channel 330 (shown in FIG. 42 ) of the needle 156.

[0393] Another function of funnel 182 and aperture 180 is to support needle 156 and / or sensor 138 against buckling forces during insertion of needle 156 and / or sensor 138 into a recipient.

[0394] Funnel 182 and holes 180 also protect against accidental needle stick injuries (because they are so small, for example, that a finger cannot reach needle 156 before it is deployed).

[0395] The sensor module 134 cannot pass through the funnel 182 and the hole 180 (e.g., due to the geometric arrangement of the sensor module 134 and the funnel 182). Preventing the sensor module 134 from passing through the base 128 ensures that the sensor module 134 is removed from the recipient's body when the base 128 is removed from the recipient. The angle 338 can prevent all of the sensor 138 from passing through the hole 180 to ensure that the sensor 138 is removed from the recipient's body when the base 128 is removed from the recipient.

[0396] Any of the features described in the context of Figures 39-43 may be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of Figures 39-43 may be combined with the embodiments described in the context of Figures 1-38 and 44-70. Furthermore, any of the features of an embodiment may be combined, partially or wholly, independently with other embodiments described herein, e.g., one, two, or more than two embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0397] Does not contain needles Some embodiments use a needle to aid in inserting the glucose sensor into the subcutaneous tissue. However, some people are afraid of needles. Additionally, disposal of the needle may require the use of sharps disposal containers that are not readily available.

[0398] Many embodiments do not use a needle to insert the sensor, which can help people feel more comfortable inserting the sensor and can also eliminate the need to use a sharps disposal container to discard the applicator or portions thereof.

[0399] U.S. Patent Application Publication Nos. US2011 / 0077490(A1), US2014 / 0107450(A1), and US2014 / 0213866(A1) describe several needle-free embodiments, the entire contents of which are incorporated herein by reference.

[0400] Any of the embodiments described herein can be used with or without a needle. For example, the embodiments described in the context of Figures 1-50 can be used with or without a needle. For example, the embodiment shown in Figure 7 can be used in a very similar manner without including needle 156. In this needle-free embodiment, moving first portion 150 distally drives a distal portion of glucose sensor 138 into the skin (without the use of needle 156). In needle-free embodiments, sensor 138 can have sufficient buckling resistance such that sensor 138 does not buckle (when supported by hole 180). Sharpening the distal tip of sensor 138 can also facilitate needle-free insertion into a recipient.

[0401] Figure 56 illustrates an embodiment that is very similar to the embodiment shown in Figure 7, except that the embodiment of Figure 56 does not include a needle. The nesting assembly 132b presses the sensor 138 (which can be any type of analyte sensor) into the recipient's body. The embodiment shown in Figure 56 does not include the needle hub 162 (as shown in Figure 7), the spring 234, or the needle retraction mechanism 158, but may include any of the items and features described in the context of other embodiments herein.

[0402] FIG. 57 illustrates the first portion 150 moving distally relative to the second portion 152 of the nested assembly 132b to move the sensor module 134 and sensor 138 toward the base 128 in preparation for coupling the sensor module 134 and sensor 138 to the base 128.

[0403] 58 illustrates first portion 150 in a distal end position relative to second portion 152. Sensor module 134 and sensor 138 are coupled to base 128. Base 128 is no longer coupled to nestable assembly 132b such that nestable assembly 132b can be discarded while leaving adhesive 126 bonded to the recipient's skin (as described in the context of FIGS. 4-6).

[0404] The embodiment illustrated in FIGS. 56-58 can be integrated into the applicator system 104 shown in FIGS.

[0405] Items and features described in the context of Figures 12A-50 can also be used with the embodiments illustrated in Figures 56-58. Items and features are described in the context of specific embodiments to reduce redundancy. However, items and features shown in all figures can be combined. The embodiments described herein are designed to illustrate the interchangeability of items and features described herein.

[0406] 44 and 45 illustrate another embodiment of a nesting assembly 132g that includes a first portion 150g that moves distally relative to a second portion 152g to push a glucose sensor 138g through a hole in a base 128g and into a recipient.

[0407] The first portion 150g (e.g., a pusher) of the nesting assembly 132g can include a distal protrusion 352 that supports a substantially horizontal section of the glucose sensor 138g (e.g., as the glucose sensor 138g protrudes from the sensor module 134g). An end of the distal protrusion 352 can include a groove 354 in which at least a portion of the glucose sensor 138g is positioned. The groove 354 can aid in holding the glucose sensor 138g. The distal protrusion 352 can provide axial support for the glucose sensor 138g (e.g., to push the glucose sensor 138g distally into the recipient's tissue).

[0408] The base 128g can include a proximally-facing funnel 182g to help guide the distal end of the glucose sensor 138g into the bore 180g of the base 128g. The bore 180g can radially support the sensor 138g as the sensor 138g is inserted into the tissue of a recipient.

[0409] When the first portion 150g of the nested assembly 132g is in the proximal starting position, the distal end of the glucose sensor 138g can be positioned within the hole 180g to assist in guiding the glucose sensor 138g in the appropriate distal direction.

[0410] The hole 180g can exit from a convex distal protrusion 174g of the base 128g. The convex distal protrusion 174g can assist in tensioning the skin prior to sensor insertion. As described more fully in other embodiments, the base 128g can rest against the recipient's skin as the sensor module 134g moves distally toward the base 128g and is then coupled to the base 128g.

[0411] The nesting assembly 132g (e.g., applicator) does not include a needle. As a result, there are no sharps on the applicator, which eliminates the need for sharps protection after use. This design feature eliminates the need for a retraction spring or needle hub. The distal end of the sensor wire 138g can be sharpened to an extent that alleviates the need for needle insertion.

[0412] The nested assembly 132g (e.g., an applicator) can include a first portion 150g and a second portion 152g. The base 128g can be coupled to a distal end of the first portion 150g. The glucose sensor 138g and the sensor module 134g can be coupled to a distal end of the first portion 150g such that the first portion 150g is fixed in a proximal starting position by an interference between the first portion 150g and the second portion 152g of the nested assembly 132g such that the applicator does not require a spring, needle, or needle hub, and / or such that application of a distal force greater than a separation threshold of the interference moves the first portion 150g distally relative to the second portion 152g (e.g., until the sensor 138g is inserted into the tissue and the sensor module 134g is coupled to the base 128g).

[0413] Figures 46 and 47 illustrate a similar, needle-free embodiment. This embodiment does not use the distal protrusion 352 shown in Figure 45. Instead, the sensor module 134h includes a distally oriented channel 358 that distally orients the glucose sensor 138h such that the sensor 138h includes a bend that is at least 45 degrees and / or less than 135 degrees. A communication channel cover 362 secures the glucose sensor 138h within the distally oriented channel 358.

[0414] The embodiments illustrated in Figures 44-47 may be integrated into the applicator system 104 shown in Figures 2 and 3. Referring now to Figure 2, an electronics unit 500 (e.g., a transmitter with a battery) may be removably coupled to the sterile barrier shell 120. The remainder of the applicator system 104 may be sterilized, and then the electronics unit 500 may be coupled to the sterile barrier shell 120 (such that the electronics unit 500 is not sterilized by the remainder of the applicator system 104).

[0415] Items and features described in the context of Figures 12A-43 and 48-70 can also be used with the embodiments illustrated in Figures 44-47. Items and features are described in the context of specific embodiments to reduce redundancy. However, items and features shown in all figures can be combined. The embodiments described herein are designed to illustrate the interchangeability of items and features described herein.

[0416] Any of the features described in the context of Figures 44-47 may be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of Figures 44-47 may be combined with the embodiments described in the context of Figures 1-43 and 48-70. Furthermore, any of the features of an embodiment may be combined, partially or wholly, independently with other embodiments described herein, e.g., one, two, or more than two embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0417] In some embodiments, the sensor 138 can be deployed (e.g., into the skin of the recipient) in response to coupling the electronics unit 500 (e.g., a transmitter) to the base 128. The sensor 138 can be any type of analyte sensor (e.g., a glucose sensor).

[0418] Premature deployment of the sensor 138 can result in insertion of the sensor 138 into the wrong person and / or insufficient sensor insertion depth. Premature deployment can damage the sensor 138, which can be fragile in some embodiments. Thus, a need exists to reduce the likelihood of premature sensor deployment.

[0419] One way to reduce the likelihood of premature sensor deployment is for the system to include an initial resistance (e.g., to couple the electronics unit 500 to the base 128). The initial resistance may require a buildup of force before the initial resistance is overcome. When the initial resistance is overcome, the sensor 138 is typically deployed faster than in the case without the initial resistance (e.g., due to a buildup of force that may be at least 0.5 pounds, 1 pound, and / or less than 5 pounds). This quick deployment may reduce pain associated with the sensor insertion process.

[0420] In some embodiments, the resistance to coupling the electronics unit 500 to the base 128 after overcoming the initial resistance is less than 10 percent of the initial resistance, less than 40 percent of the initial resistance, and / or at least less than 5 percent of the initial resistance. Having a low resistance to coupling the electronics unit 500 to the base 128 after overcoming the initial resistance can allow for fast sensor insertion, which can reduce pain associated with the sensor insertion process.

[0421] 56-58 illustrate the first portion 150 deploying the sensor 138 into the recipient's skin. In some embodiments, the first portion 150 is replaced with the electronics unit 500 shown in FIG. 4 such that coupling the electronics unit 500 to the base 128 presses the sensor 138 into the recipient's skin. Referring now to FIGS. 4 and 56-58, the protrusion 240 (as described in other embodiments) can be part of the electronics unit 500 such that moving the electronics unit distally relative to the second portion 152 and / or coupling the electronics unit 500 to the base 128 requires overcoming an initial resistance of the protrusion 240.

[0422] In some embodiments where the sensor 138 is configured to be deployed (e.g., into the recipient's skin) in response to mating the electronics unit 500 to the base 128, the nesting assembly 132b is not used. Instead, features of the base 128 provide an initial resistance for mating the electronics unit 500 to the base 128. The locking features 230 of the base 128 can be mated with corresponding features of the electronics unit 500, although the locking features 230 of FIG. 33 are used for a different purpose in some other embodiments. This mating may require overcoming an initial resistance.

[0423] Any of the features and embodiments described in the context of Figures 1-70 may be applicable to all aspects and embodiments in which a sensor 138 is deployed (e.g., into the skin of a recipient) in response to coupling an electronics unit 500 (e.g., a transmitter) to a base 128. Vertical lock

[0424] After inserting a glucose sensor using a nesting assembly (e.g., an applicator), the needle used to insert the glucose sensor may inadvertently penetrate another person. To protect against this risk, the nesting assembly may protect people from subsequent needlestick injuries by preventing a first portion of the nesting assembly from moving distally relative to a second portion after the sensor is inserted into a recipient.

[0425] 48 illustrates a perspective cross-sectional view of the nestable assembly 132i including a first portion 150i and a second portion 152i. Referring now to FIGS. 48-50, the first portion 150i is configured to nest distally relative to the second portion 152i. The second portion 152i of the nestable assembly 132i can include a proximal protrusion 364 that can slide past a lockout feature 366 of the first portion 150i of the nestable assembly 132i as the first portion 150i moves distally.

[0426] The proximal protrusion 364 is biased such that, upon engagement of the lockout feature 366, elastic deformation of the proximal protrusion 364 creates a force configured to push the proximal protrusion 364 into the bottom of the lockout feature 366.

[0427] The proximal protrusion 364 does not catch on the lockout feature 366 when the first portion 150i initially moves distally. Once the first portion 150i is in the distal end position, the spring can push the first portion 150i to the second proximal position. Rather than returning to the starting proximal position, the proximal protrusion 364 catches on the lockout feature 366 (due to the bias of the proximal protrusion 364 and the distally facing notch 368 of the lockout feature 366).

[0428] Once the proximal end of the proximal projection 364 is captured in the lockout feature 366, the rigidity of the proximal projection 364 prevents the first portion 150i of the nested assembly 132i from moving distally a second time.

[0429] As the first portion 150i moves distally relative to the second portion 152i, the ramp portion 370 of the first portion 150i pushes the proximal protrusion 364 outward (towards the lockout feature 366). The proximal protrusion 364 can be positioned between two distal protrusions 372 of the first portion 150i. The distal protrusions 372 can guide the proximal protrusion 364 along the ramp portion 370.

[0430] As a portion of the proximal protrusion 364 slides along the ramp 370 (as the first portion 150i moves distally), the ramp bends the proximal protrusion 364 until the portion of the proximal protrusion 364 that was previously between the two distal protrusions 372 is no longer between the distal protrusions 372. Once the portion of the proximal protrusion 364 is no longer between the two distal protrusions 372, the proximal protrusion 364 becomes caught in the notch 368. The notch 368 can be part of the distal protrusion 372.

[0431] The second portion 152i of the nestable assembly 132i can include a proximal protrusion 364 that can be oriented at an angle between 0 and 45 degrees relative to the central axis. The first portion 150i of the nestable assembly 132i can include features that cause the proximal protrusion 364 to follow a first path when the first portion 150i moves distally and then a second path when the first portion 150i moves proximally. The second path includes a locking feature 366 that prevents the first portion 150i from moving distally a second time.

[0432] The first portion 150i can include a ramp portion 370 that guides the proximal protrusion 364 along the first path. A distal protrusion (e.g., ramp portion 370) of the first portion 150i can urge the proximal protrusion 364 into the second path as the first portion 150i moves proximally. The proximal protrusion 364 can be a flex arm. The stop 366 can include a distally facing notch 368 that hooks onto the proximal end of the proximal protrusion 364.

[0433] 48 and 50, the nested assembly 132i can include a sensor module 134i. The sensor module 134i can be any of the sensor modules described herein.

[0434] Any of the features described in the context of Figures 48-50 may be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of Figures 48-50 may be combined with the embodiments described in the context of Figures 1-47 and 51-70. Furthermore, any of the features of an embodiment may be combined, partially or wholly, independently with other embodiments described herein, e.g., one, two, or more embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0435] Dual Spring Assembly Partial sensor insertion can lead to suboptimal sensing. In some cases, partial sensor insertion can result in a needle stick injury (due to the needle not being retracted into a protective housing). Thus, a need exists for a system that ensures complete sensor insertion.

[0436] The embodiment illustrated in Figures 61-64 dramatically reduces the probability of partial sensor insertion by preventing sensor insertion from occurring until sufficient potential energy has been stored in the system. The potential energy is stored in a first spring 402.

[0437] The system includes many of the items (e.g., base 128 and sensor module 134) from the embodiment illustrated in Figure 7. The system includes an optional needle 156 and needle hub 162. The embodiment illustrated in Figures 61-64 can also be configured to not include a needle by removing the needle 156, second spring 234, needle hub 162, and needle retraction mechanism 158.

[0438] The nestable assembly 132k has three portions 150k, 152k, 392. Moving the third portion 392 distally relative to the second portion 152k stores energy in the first spring 402 (by compressing the first spring 402). When the first portion 150k is unlocked from the second portion 152k, the energy stored in the compressed first spring 402 is used to push the first portion 150k distally relative to the second portion 152k, driving the sensor 138 (shown in FIG. 7) into the recipient's skin.

[0439] First portion 150k is locked to second portion 152k to ensure that first portion 150k does not move distally relative to second portion 152k until first spring 402 is sufficiently compressed (and thus has sufficient stored energy), at which point the system unlocks first portion 150k from second portion 152k to allow the stored energy to move sensor 138 (and, in some embodiments, needle 156) into the recipient's skin.

[0440] The nesting assembly 132k can lock the third portion 392 to the second portion 152k in response to the third portion 392 reaching a sufficiently distal position relative to the second portion 152k. The protrusion 408 can mate with the hole 410 to lock the third portion 392 to the second portion 152k.

[0441] Some embodiments do not include the locking protrusion 408 and do not lock the third portion 392 to the second portion 152k in response to the third portion 392 reaching a sufficiently distal position relative to the second portion 152k.

[0442] In some embodiments, a sufficiently distal location is at least 3 millimeters, at least 5 millimeters, and / or less than 30 millimeters distal to the proximal starting location.

[0443] The nested assembly 132k can lock the first portion 150k to the second portion 152k in response to the first portion 150k reaching a sufficiently distal position relative to the second portion 152k. The protrusions 412 (e.g., distal protrusions) can engage the holes 414 (e.g., at a surface that is within ±30 degrees of perpendicular to a central axis of the nested assembly 132k) to lock the first portion 150k to the second portion 152k.

[0444] Some embodiments include a needle 156 to aid in inserting the sensor into the recipient's skin. In embodiments that include a needle 156, the nestable assembly 132k may include a needle retraction mechanism 158, described in the context of FIG. 7. Moving the first portion 150k to a sufficiently distal position relative to the second portion 152k triggers (e.g., unlatches) the needle retraction mechanism 158, allowing the second spring 234 to retract the needle 156.

[0445] FIG 61 illustrates a system for applying an on-skin sensor assembly 600 (shown in FIGS. 4-6) to the skin of a recipient. The system includes a nestable assembly 132k having a first portion configured to move distally relative to a second portion 152k along a path from a proximal start position (e.g., the position shown in FIG. 61) to a distal position (e.g., the position shown in FIG. 64), a sensor 138 (shown in FIG. 64) coupled to the first portion 150k, and a base 128 including an adhesive 126 configured to couple the sensor 138 to the skin. The nestable assembly 132k may further include a third portion 392 configured to move distally relative to the second portion 152k.

[0446] In some embodiments, the first portion 150k is positioned inside the second portion 152k such that the second portion 152k wraps around the first portion 150k in a cross section taken perpendicular to the central axis of the nested assembly 132k.

[0447] In some embodiments, the first spring 402 is positioned between the third portion 392 and the second portion 152k such that moving the third portion 392 distally relative to the second portion 152k compresses the first spring 402. The first spring 402 can be a metal helical spring and / or a metal conical spring. In some embodiments, the first spring 402 is a molded feature as part of the third portion 392, as part of the second portion 152k, or as part of the first portion 150k. The first spring 402 can be molded plastic.

[0448] The nestable assembly 132k can be configured such that the first spring 402 is not compressed in the proximal start position and / or during storage. In some embodiments, the nestable assembly 132k can be configured such that the first spring 402 is not compressed by more than 15 percent in the proximal start position and / or during storage (e.g., to avoid detrimental spring relaxation and / or creep of other components, such as at least one of the third portion 392, the second portion 152k, and the first portion 150k).

[0449] Some embodiments that include needle 156 do not include needle hub 162. In these embodiments, second spring 234 can be positioned between second portion 152k and first portion 150k such that moving first portion 150k distally relative to second portion 152k compresses second spring 234, which in turn pushes first portion 150k proximally relative to second portion 152k to retract needle 156 (e.g., after sensor insertion).

[0450] In some embodiments, the second spring 234 is compressed while the nested assembly 132k is in the proximal start position. For example, the second spring 234 can be compressed at a factory during assembly of the nested assembly 132k such that when a user receives the nested assembly 132k, the second spring 234 is already compressed (sufficiently compressed to store the needle 156).

[0451] The second spring 234 can have any of the attributes and characteristics associated with the spring 234 described in the context of other embodiments herein (eg, in the context of the embodiment of FIG. 7).

[0452] In some embodiments, movement of the sensor module 134 (e.g., an analyte sensor module) and the sensor 138 (e.g., an analyte sensor) relative to the base 128 may be as described in the context of other embodiments (e.g., as shown by the progression illustrated by Figures 7-11).

[0453] In a proximal starting position of the nested assembly 132k, the first portion 150k can be locked to the second portion 152k. The system can be configured such that moving the third portion 392 distally relative to the second portion 152k unlocks the first portion 150k from the second portion 152k.

[0454] In some embodiments, a first proximal projection 394 having a first hook 396 passes through a first hole 398 in the second portion 152k to lock the first portion 150k to the second portion 152k. The third portion 392 can include a first distal projection 404. The system can be configured such that moving the third portion 392 distally relative to the second portion 152k engages a ramp portion 406 to bend the first proximal projection 394 to unlock the first portion 150k from the second portion 152k.

[0455] In some embodiments, the sensor 138 is positioned within the second portion 152k while the base 128 protrudes from the distal end of the system such that the system is configured to couple the sensor 138 to the base 128 by moving the first portion 150k distally relative to the second portion 152k.

[0456] In some embodiments, the sensor module 134 is coupled to a distal portion of the first portion 150k such that moving the first portion 150k to a distal position couples the sensor module 134 to the base 128. This coupling may be as described in the context of other embodiments herein. The sensor 138 may be coupled to the sensor module 134 while the first portion 150k is positioned in a proximal start position.

[0457] The system can be configured such that the third portion 392 moves distally relative to the second portion 152k before the first spring 402 moves the first portion 150k distally relative to the second portion 152k. The system can be configured such that moving the third portion 392 distally relative to the second portion 152k unlocks the first portion 150k from the second portion 150k and locks the third portion 392 to the second portion 152k.

[0458] The first protrusion 408 engages with a hole 410 in at least one of the second portion 152k and the third portion 392 to lock the third portion 392 to the second portion 152k.

[0459] In some embodiments, the system includes a second protrusion 412 that engages with at least one hole 414 of the first portion 150k and the second portion 152k to lock the first portion 150k to the second portion 152k in response to the first portion 150k moving distally relative to the second portion 152k.

[0460] In some embodiments, the first spring 402 is positioned between the third portion 392 and the second portion 152k such that moving the third portion 392 distally relative to the second portion 152k compresses the first spring 402 and unlocks the first portion 150k from the second portion 152k, allowing the compressed first spring 402 to push the first portion 150k distally relative to the second portion 152k, pushing at least a portion of the sensor 138 out of the distal end of the system and triggering the needle retraction mechanism 158, allowing the second spring 234 to retract the needle 156.

[0461] In yet another aspect, disclosed herein is a dual spring-based sensor insertion device having a pre-connected sensor assembly (i.e., an analyte sensor electrically coupled to at least one electrical contact prior to sensor deployment). Such a sensor insertion device provides convenient and reliable insertion of the needle into the user's skin, as well as reliable retraction of the needle after the sensor is inserted, features that provide convenience to the user, as well as predictability and reliability of the insertion mechanism. The reliability and convenience of a dual spring-based sensor insertion device with automatic insertion and retraction provides a significant advancement in the field of sensor insertion devices. Furthermore, such a device can provide both safety and storage stability.

[0462] In some embodiments, the insertion device can include a first spring and a second spring. In such embodiments, one or both of the first spring and the second spring can be integrally formed with a portion of the nestable assembly, such as the first and second portions of the nestable assembly. In some embodiments, one or both of the first spring and the second spring can be formed separately and operably coupled to a portion of the nestable assembly. For example, in some embodiments, the insertion spring can be integrally formed with a portion of the nestable assembly, while the storage spring is a separate part operably coupled to a portion of the nestable assembly.

[0463] In some embodiments, one or both of the first and second springs can be configured to be tensioned during energy application, rather than being configured to be compressed during energy application. In these embodiments, the coupling between the springs and portions of the nested assembly, as well as the coupling between moving portions of the assembly (e.g., at rest and during activation, deployment, and retraction), can be tailored to drive and / or facilitate desired activities and reactions in the system. In an embodiment using a tensioned storage spring to drive the insertion process, the storage spring can be coupled to or integrally formed with the second portion of the nested assembly. In such an embodiment, the storage spring can be pre-tensioned at rest. In other such embodiments, the storage spring can be untensioned at rest and tensioned during the sensor insertion process.

[0464] In some embodiments, one or both of the first and second springs can be substantially unenergized and / or unstressed when the system is at rest. In some embodiments, one or both of the first and second springs can be energized and / or stressed when the system is at rest. As used herein, the term "energized" means that sufficient potential energy is stored in the spring to perform desired activities and reactions in the system. In some embodiments, the first spring can be partially energized at rest such that a user can apply a smaller amount of force to bring the first spring into a fully energized state. In some embodiments, the second spring can be partially energized at rest such that the energy stored in the first spring (either at rest or after energization by the user) can provide a force to energize the second spring. In some embodiments, the energy stored in the first spring can provide a force sufficient to energize the second spring to at least retract the needle from the skin. In some embodiments, one or both of the first and second springs can be compressed or tensioned 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% of their resting state, while in other embodiments, one or both of the first and second springs can be compressed or tensioned 50% or less, 40% or less, 30% or less, 20% or less, 15% or less, 10% or less, 5% or less, or 0% of their resting state.

[0465] In embodiments where the first and second springs are substantially unenergized at rest, the springs can be stressed by the same, similar, or completely different amounts. In embodiments where the first and second springs are substantially energized at rest, the springs can be stressed by the same, similar, or completely different amounts. In embodiments where the second spring is substantially unenergized at rest, the first spring can be configured to store sufficient energy to drive both a desired movement in the system (e.g., movement of the first portion in a desired direction) as well as the energization of the second spring.

[0466] 71-75, another embodiment of a system 104m for applying an on-skin sensor assembly to a recipient's skin is illustrated. The embodiment illustrated in FIGS. 71-75 can reduce the likelihood of incomplete sensor insertion by preventing sensor insertion from occurring until sufficient potential energy has been stored in the system. The potential energy for inserting the sensor can be stored in an actuator, such as a first spring 402m. The embodiment can provide other advantages, such as controlled speed, controlled force, and improved user experience.

[0467] The system 104m can include many features from the embodiment illustrated in FIG. 7, such as the needle 156, the base 128, and the sensor module 134. The system 104m can include alternative elements, such as, but not limited to, the needle hub 162m, the second spring 234m, and the needle retraction mechanism 158m. The embodiment illustrated in FIGS. 71-75 can also be configured to not include a needle by removing the needle 156, the second spring 234m, the needle hub 162m, and the needle retraction mechanism 158m. In such an embodiment, the sensor can be a self-insertable sensor.

[0468] System 104m can include a number of features (e.g., nested assembly 132m) similar to the features of the embodiment illustrated in FIGS. 61-64, including first portion 150m, second portion 152m, and third portion 392m, including locking features 396m and 398m configured to releasably lock first portion 150m to second portion 152m until third portion 392m reaches a sufficiently distal position relative to second portion 152m to compress first spring 402m and store sufficient energy in spring 402m to drive insertion of sensor 138 (and in some embodiments needle 156) into the recipient's skin, and locking features 396m and 398m configured to lock third portion 392m to second portion 152m (e.g., to prevent proximal movement of third portion 392m relative to second portion 152m) in response to third portion 392m reaching a sufficiently distal position relative to second portion 152m. locking features 408m and 410m, unlocking features 404m and 406m configured to unlock locking features 396m and 398m at least after third portion 392m has been locked to second portion 152m and / or after first spring 402m has been sufficiently compressed such that first portion 150m has reached a sufficiently distal position relative to second portion 152m to drive sensor 138 (and in some embodiments needle 156) into the skin of the recipient. In response to this, the needle 156 is engaged with the first portion 150m via the second portion 152m via locking features 412m and 414m configured to lock the first portion 150m to the second portion 152m, and the needle retraction mechanism 158m configured to unlock the needle hub 162m from the first portion 150m (e.g., to allow proximal movement of the needle hub 162m relative to the first portion 150m) once the needle hub 162m has reached a sufficiently distal position whereby the second spring 234m has retracted the needle 156.

[0469] FIG. 71 illustrates a cross-sectional perspective view of the applicator system 104m in a resting state (e.g., prior to activation and deployment by a user of the applicator system when provided to a consumer). As illustrated in the drawing, the first spring 402m can be neither tensioned nor compressed such that the first spring is substantially unenergized. In some embodiments, the first spring 402m can be slightly tensioned or slightly compressed (e.g., not more than 15 percent tensioned or compressed) such that the first spring is substantially or almost unenergized in the resting state. In some embodiments, the first spring can be substantially unenergized, e.g., minimally energized in the resting state to the extent that it does not create any kind of chain reaction in the system.

[0470] In the embodiment illustrated in Figs. 71-75, the first spring 402m is integrally formed as part of the third portion 392m. In some embodiments, the first spring 402m can be integrally formed as part of other components of the system 104m, such as, but not limited to, the first portion 150m, the second portion 152m, etc. Integral formed springs such as those illustrated in Figs. 71-75 provide advantages including a reduced number of parts in the system as well as a reduced amount of assembly process. The first spring 402m can be molded plastic. As illustrated in Fig. 71, in a resting state, the second spring 234m is also substantially unenergized (e.g., not tensioned or compressed by more than 15 percent). The second spring 234m is integrally formed as part of the needle hub 162m. In some embodiments, the second spring 234m can be integrally formed as part of other components of the system 104m, such as, but not limited to, the first portion 150m, the second portion 152m, the base 128, etc. The second spring 234m can be molded plastic. Such a configuration can simplify the manufacture and assembly of the system 104m while avoiding detrimental relaxation and / or creep of the first spring 402m, the second spring 234m, or other system components 104m during storage and / or prior to deployment. It is also contemplated that in other embodiments, the first spring 402m and / or the second spring 234m can be constructed of metal.

[0471] In some embodiments, the first spring 402m and / or the second spring 234m can be made of molded plastic, such as, but not limited to, polycarbonate (PC), acrylonitrile butadiene styrene (ABS), PC / ABS blends, nylon, polyethylene (PE), polypropylene (pp), and acetal. In some embodiments, the first spring 402m or the second spring 234m has a spring constant of less than 10 lb / in.

[0472] The applicator system 104 can be energized by moving one component relative to the other. For example, moving the third portion 392m distally relative to the second portion 152m can store energy in the first spring 402m as it compresses against the first portion 150m when the second portion 152m is placed on the recipient's skin or another surface. The third portion 392m can be moved distally until the locking features 408m and 410m (see FIG. 73) engage together. In some embodiments, the third portion 392m can be moved further distally until the unlocking feature 404m engages the locking feature 396m. The unlocking feature 404m can engage and disengage the locking feature 396m, allowing the first portion 150m to be moved distally. In some embodiments, the locking features 408m and 410m are engaged together before the locking feature 396m is disengaged from the locking feature 398m. In other embodiments, the unlocking feature 404m can engage the locking feature 396m, disengage the locking feature 396m from the locking feature 398m, and engage the locking features 408m and 410m together. In some embodiments, the locking feature 408m is a protrusion featuring a hook portion, the locking feature 410m is a hole featuring an angled surface, the unlocking feature 404m is a distal protrusion featuring an angled surface, the locking feature 396m is a hook featuring a ramp portion 406m, and the locking feature 398m is an aperture. The sensor module 134 remains in the proximal start position while the first spring 402m is energized.

[0473] 72 illustrates a cross-sectional perspective view of the applicator system 104m with the first spring 402m compressed and the unlocking features 404m and 406m engaged to unlock the first portion 150m from the second portion 152m. The sensor module 134 remains in its proximal starting position and the second spring 234m remains in a substantially unenergized state until the first portion 150m is unlocked from the second portion 152m. FIG. 73 illustrates a rotated cross-sectional perspective view of the applicator system 104m, showing the locking features 408m and 410m engaged to prevent proximal movement of the third portion 392m relative to the second portion 152m. In some embodiments, as shown in FIG. 73, the system can include a secondary locking feature 409m configured to cooperate with opening 410m to prevent the third portion 392 from falling or otherwise separating from the remainder of the system 104m prior to deployment.

[0474] 74 illustrates a cross-sectional perspective view of the applicator system 104m with the system 104m activated by disengagement of the first portion 150m from the second portion 152m. As can be seen in FIG. 74, when the first portion 150m and the second portion 152m are disengaged or released, the potential energy stored in the first spring 402m drives the first portion 150m in a distal direction along with the needle hub 162m and the sensor module 134. This movement compresses the second spring 234m and deploys the needle 156 and the sensor module 134 distally to a distal insertion position where the sensor module 134 is engaged to the base 128 and the needle 156 extends distally of the base 128. When the needle 156 and sensor module 134 reach the distal insertion position, the locking features 412m, 414m (see FIG. 73) engage to prevent proximal movement of the first portion 150m relative to the second portion 152m, and the unlocking features of the needle retraction mechanism 158m (e.g., the latch 236m comprising the proximal protrusion 170m, the release feature 160m, and the end 164m of the release feature 160m and the overhang 166m of the first portion 150m) cooperate to release the latch 236m. Optionally, the user can hear a clicking sound after the second spring 243m is activated, which can inform the user that the cap is locked in place.

[0475] When the latch 236m is released, the potential energy stored in the compressed second spring 234m drives the needle hub 162m back in the proximal direction while the first portion 150m, along with the sensor module 134, remains in the distal deployed position. The stored potential energy can be between 0.25 pounds and 4 pounds. In a preferred embodiment, the stored potential energy is approximately 1 to 2 pounds. FIG. 75 illustrates a cross-sectional perspective view of the applicator system 104m with the sensor module 134 coupled to the base 128 in the distal deployed position and the needle hub 162m stored in the proximal stored position.

[0476] A system configured according to the embodiments can provide an inherently safe and shelf-stable system for inserting a sensor. A spring in an unloaded state (i.e., substantially uncompressed and substantially unactivated) cannot be prematurely fired. Indeed, such a system is less susceptible to accidental firing without direct interaction from a user since the first or second springs are substantially unenergized during storage. Furthermore, it is envisioned that a system with a pre-activated, substantially uncompressed spring will possess shelf-stable properties since the elements of the system are not subject to force or phase changes over time (creep, environmental, time-dependent load condition defects, etc.) compared to a pre-energized insertion device. The substantially uncompressed first and second springs can provide a system configured such that the substantially unenergized first spring 404m provides sufficient energy to drive the sensor from a proximal position to a distal position and further transfers energy to the second spring 234m to drive the needle to a fully retracted position.

[0477] Other embodiments may also be configured to achieve these advantages. For example, Figures 76-79 illustrate another embodiment of a system 104n for applying an on-skin sensor assembly to the skin of a host. The system 104n includes many features similar to those of the embodiment illustrated in Figures 71-75 (e.g., a nested assembly 132n including a first portion 150n, a second portion 152n, and a third portion 392n, a needle hub 162n, a first spring 402n, and a second spring 234n). In the embodiment illustrated in Figures 76-79, the first spring 402n is formed separately from and operably coupled to the third portion 392n. The second spring 234n is formed separately from and operably coupled to the needle hub 162n. The first spring and / or the second spring may each be a helical spring having a circular cross-section. In some embodiments, the first spring and / or the second spring can each be comprised of a helical spring having a square or non-circular cross-section. The first spring and / or the second spring can be comprised of a metal, such as, but not limited to, stainless steel, steel, or other types of metal. Alternatively, in some embodiments, one or both of the first spring and the second spring can be integrally formed with a portion of the applicator assembly. For example, but not limited to, in some embodiments, the first spring can be integrally formed with the first portion. In some embodiments, the second spring can be integrally formed with the needle hub. In some embodiments, the first spring and / or the second spring can be a molded plastic, such as, but not limited to, PC or ABS.

[0478] FIG. 76 illustrates a side cross-sectional view of the system 104n in a resting state, with the first spring 402n and the second spring 234n both in an unstressed and unenergized state. In the resting state, the first portion 150n can be fixed relative to the second portion 152n at least in an axial direction, while the third portion 392n is movable relative to the first portion 150n at least in a distal direction. The first portion 150n and the second portion 152n can be fixed relative to each other in any suitable manner, for example, by cooperating releasable locking features (e.g., locking features as described in FIGS. 71-75, or similar features) coupled to or forming part of the first portion 150n and the second portion 152n. The system 104n includes an on-skin component 134n releasably coupled to a needle hub 162n. The on-skin component may comprise a sensor module, such as the sensor module 134 described in connection with FIG. 3, or a combined sensor module and base assembly, or an integrated sensor module / base / transmitter assembly, or any other component that is desirably applied to the recipient's skin, whether directly or indirectly, for example via an adhesive patch.

[0479] In the rest state illustrated in FIG. 76, the on-skin component 134n is disposed in a proximal start position between the proximal and distal ends of the system 104n. The distal end of the needle 156 can also be disposed between the proximal and distal ends of the system 104n. In the rest state, the distal end of the first spring 402n abuts the proximal-facing surface of the first portion 150n. Application of a force to the proximal-facing surface of the third portion 392n moves the third portion 392n distally relative to the first portion 150n, compressing the first spring 402n and thus energizing it. In some embodiments, this process can be similar to the spring energy application process described in connection with FIG. 71.

[0480] FIG. 77 illustrates a side cross-sectional view of the applicator system of FIG. 76 with the first spring 402n energized. When the third portion 392n has moved sufficiently distally to energize the first spring 402n, the third portion 392n is fixed relative to the second portion 152n, at least in the axial direction. Simultaneously or nearly simultaneously (e.g., in unison or subsequently), the first portion 150n is movable relative to the second portion 152n, at least in the distal direction. The third portion 392n and the second portion 150n can be fixed relative to one another in any suitable manner, such as by cooperating locking features (e.g., locking features as described in FIGS. 71-75, or similar features) coupled to or forming part of the third portion 392n and the second portion 152n, the third portion and the second portion being configured to engage one another when the third portion 392n reaches a sufficiently distal position. The first and second portions 150n, 152n may be permitted to move relative to one another by structure(s) (not shown in Figures 76-79) configured to release the locking feature that couples them together in the resting configuration illustrated in Figure 76. The first portion 150n includes an overhang (sometimes referred to as a detent, undercut, and / or needle hub engagement feature) 166n that cooperates with the release feature 160n of the needle hub 162n to secure the needle hub 162n relative to the first portion 150n while the system is in the resting position and during energization of the spring 392n.

[0481] 78 illustrates a side cross-sectional view of the system 104n with the first and second portions 150n, 152n unlocked, activating the first spring 402n, allowing the energy stored therein to drive the first portion 150n in a distal direction. The movement of the first portion 150n also urges the needle hub 162n (as well as the on-skin component 134n coupled to the needle hub 162n) in a distal direction, compressing the second spring 234n against a proximally facing surface of the second spring 152n, coupling the on-skin component 134n to the base 128n, and driving the needle 156 to the distal insertion position illustrated in FIG. When the needle hub 162n reaches a distal position sufficiently to accomplish these functions, the end of the release feature 160n contacts the ramp portion 170n of the second portion 152n, compressing the release feature 160n inward (toward the central axis of the system 104n) and disengaging the end of the release feature 160n from the overhang 166n. In some embodiments, this process may be similar to the spring compression process described in connection with FIG. 74. In some embodiments, the ramp portion 170n is a proximally facing ramp portion. In other embodiments, the ramp portion 170n is a distally facing ramp portion (not shown). In some embodiments, one or more release features may be configured to compress inward (or otherwise release) by relative rotational motion of certain components of the system, such as by twisting or other rotational motion of the first portion relative to the second portion. In some embodiments, one or more release features may extend in a direction perpendicular to the axis of the system and / or may extend circumferentially around the axis of the system instead of (or in addition to) extending generally parallel to the axis of the system as shown in FIG.

[0482] 79 illustrates a side cross-sectional view of the system 104n with the needle hub 162n disengaged from the overhang 166, actuating the second spring 234n and allowing the energy stored therein to drive the needle hub 162n in a proximal direction. As the needle hub 162n retracts to a proximal position, the on-skin component 134n disengages from the needle hub 162n and remains in the deployed position and is coupled to the base 128n.

[0483] 80-85 illustrate another embodiment of a system 104p for applying an on-skin sensor assembly to the skin of a host. A sensor insertion system such as that illustrated in FIGS. 80-85 can provide increased predictability in the spring displacement of the second energized spring 234p since the second spring 234p is already compressed. Such a configuration can help ensure that the needle is properly retracted a sufficient distance from the skin. In some embodiments, a system incorporating a pre-energized storage spring can provide effective and reliable insertion and retraction while requiring a user to apply less force than, for example, a system in which both the insertion spring and the storage spring are substantially in an unenergized state prior to deployment, making such a configuration more convenient for at least some users. Additionally, in some embodiments, a system incorporating one or more metal springs can provide effective and reliable insertion and retraction while requiring a user to apply less force than a system in which both the insertion spring and the storage spring are constructed of plastic. The system 104p includes many features similar to those of the embodiment illustrated in FIGS. 76-79 (e.g., a nested assembly 132p including a first portion 150p, a second portion 152p, and a third portion 392p, a needle hub 162p, a first spring 402p, a second spring 234p, an on-skin component 134n, and a base 128p). In the embodiment illustrated in FIGS. 80-85, the first spring 402p is formed separately from and operably coupled to the third portion 392p. The second spring 234p is formed separately from and operably coupled to the needle hub 162p. The first spring and / or the second spring can be constructed of metal. Alternatively, in some embodiments, one or both of the first spring and the second spring can be integrally formed with a portion of the applicator assembly. For example, without limitation, in some embodiments, the first spring can be integrally formed with the first portion, and in some embodiments, the second spring can be integrally formed with the needle hub.In some embodiments, the first spring and / or the second spring may be molded plastic.

[0484] FIG. 80 illustrates a side cross-sectional view of the system 104p in a resting state in which the first spring 402p is substantially unstressed and unenergized, while the second spring 234n is pre-energized (e.g., compressed). In the resting state illustrated in FIG. 80, the first portion 150p is locked to the second portion 152p to prevent proximal or distal movement of the first portion 150p relative to the second portion 152p. The first portion 150p and the second portion 152n can be locked together in any suitable manner, for example, by cooperating releasable locking features 396p and 398p (see FIGS. 84 and 85) coupled to or forming part of the first portion 150p and the second portion 152p. The needle hub 162n is also releasably secured to the first portion 150p. The needle hub 162n may be secured to the first portion 150p in any suitable manner, for example, by a feature of the first portion 150p configured to engage or compress a release feature (sometimes referred to as a needle hub resistance feature) 160p of the needle hub 162p.

[0485] In the rest state illustrated in FIG. 80, the on-skin component 134p is disposed in a proximal start position such that the distal end of the needle 156 is disposed between the proximal and distal ends of the system 104p. In the rest state, the distal end of the first spring 402p abuts the proximally facing surface of the first portion 150p. Application of a force to the proximally facing surface of the third portion 392p moves the third portion 392p distally relative to the first portion 150p, compressing and thus energizing the first spring 402p. In some embodiments, this process may be similar to the spring energization process described in connection with FIG. 76.

[0486] Figure 81 illustrates a side cross-sectional view of the system 104p of Figure 80 after the third portion 392n has moved sufficiently to a distal position to energize the first spring 402p and optionally lock the third portion 392p to the second portion 152p. The third portion 392n and the second portion 150n can be locked to one another in any suitable manner, such as by cooperating releasable locking features coupled to or forming part of the third portion 392p and the second portion 152p (e.g., the locking features described in Figures 76-79, or similar features). At or near the same time (e.g., simultaneously or subsequently) the third portion 392p engages with the second portion 152p, the unlocking features 404p and 406p (see Figures 84 and 85) cooperate to release the lock between the first portion 150p and the second portion 152p.

[0487] 82 illustrates a side cross-sectional view of system 104p with first spring 402p actuated to drive first portion 150p in a distal direction. The movement of first portion 150p also urges needle hub 162p (as well as on-skin component 134p coupled to needle hub 162p) in a distal direction, coupling on-skin component 134p to base 128p and further driving needle 156 distally past the distal end of system 104p. At or about the same time (e.g., immediately prior to, in unison with, or subsequently to) the needle hub 162p reaches the distal insertion position illustrated in FIG. 82, the end of the release feature 160p contacts the ramp portion 170p of the second portion 152p, compressing the release feature 160p inward (toward the central axis of the system 104p), unlocking the needle hub 162p from the first portion 150p, and releasing or activating the second spring 234p. In some embodiments, the ramp portion 170p is a proximally facing ramp portion. In other embodiments, the ramp portion 170p is a distally facing ramp portion (not shown). Activation of the second spring 234p biases the needle hub 162p in a proximal direction.

[0488] 83 illustrates a side cross-sectional view of the system 104p with the needle hub 162p unlocked from the first portion 150p and retracted to a proximal position. As the needle hub 162p retracts to a proximal position, the on-skin component 134p decouples from the needle hub 162p and remains in a deployed position and is coupled to the base 128p.

[0489] Fig. 84 illustrates a perspective view of the system 104p in a quiescent state, with the first portion 150p and the third portion 392p shown in cross-section to better illustrate certain portions of the system 104p, such as the locking features 396p, 398p and the unlocking features 404p, 406p. Fig. 85 illustrates another perspective view of the system 104p, also showing the first portion 150p and the third portion 392p in cross-section, with the first spring 402p in an energized but not yet activated state.

[0490] 86-88 illustrate another embodiment of a system 104q for applying an on-skin sensor assembly to a recipient's skin, in which the insertion spring is in a pre-compressed state and the storage spring is in a substantially uncompressed state. Such a system allows a user to activate needle insertion and retraction in fewer steps. It is contemplated that advantages may include a relatively smaller applicator size and a more predictable spring displacement of the first spring, since the first spring is already compressed, thereby helping to ensure proper needle insertion into the user's skin. In some embodiments, a system incorporating a pre-energized insertion spring may provide effective and reliable insertion and retraction, while requiring a lower amount of user-applied force than, for example, a system in which both the insertion spring and the storage spring are in a substantially unenergized state prior to deployment, making such a configuration more convenient for at least some users. System 104q includes a number of items similar to the features of the embodiment illustrated in FIGS. 76-79 (e.g., nested assembly 132q including first portion 150q, second portion 152q, and third portion 392q, needle hub 162q, first spring 402q, second spring 234q, on-skin component 134q, and base 128q). In system 104q, first spring 402q is formed separately from and operably coupled to third portion 392q. Second spring 234q is formed separately from and operably coupled to needle hub 162q. The first spring and / or second spring can be constructed of metal. Alternatively, in some embodiments, one or both of the first spring and second spring can be integrally formed with a portion of the applicator assembly.

[0491] FIG. 86 illustrates a side cross-sectional view of the system 104q in a resting state where the first spring 402q is already in an energized state, but the second spring 234q is in a substantially unenergized state (e.g., in a substantially uncompressed or unstressed state, and may be partially energized). In the resting state illustrated in FIG. 86, the first portion 150q is locked to the second portion 152q to prevent proximal or distal movement of the first portion 150q relative to the second portion 152q. The first portion 150q and the second portion 152q can be locked together in any suitable manner, for example, by cooperating releasable locking features (e.g., the locking features described in FIGS. 76-79 or other suitable locking features) coupled to or forming part of the first portion 150q and the second portion 152q. The needle hub 162q is also releasably locked to the first portion 150q. The needle hub 162q can be locked to the first portion 150q in any suitable manner, for example, by a feature of the first portion 150q configured to engage or compress the release feature 160q of the needle hub 162q. The third portion 392q and the second portion 152q are also locked together to prevent relative axial movement of the third portion 392p and the second portion 152q. The third portion 392q and the second portion 152q can be locked together in any suitable manner, for example, by a locking feature (not shown in FIGS. 86-89 ) that can be coupled to or form part of the third portion 392q and the second portion 152q. In the rest state illustrated in FIG. 80 , the on-skin component 134q is disposed in a proximal start position such that the distal end of the needle 156 is disposed between the proximal and distal ends of the system 104q.

[0492] To trigger deployment of system 104q, a locking feature coupling first portion 150q to second portion 152q can be unlocked, decoupling the two portions and thereby releasing or activating first spring 402q. The locking feature can be unlocked by a user-activated trigger mechanism, such as, for example, a button located on or in a top or side surface of system 104q or a twist release feature configured to disengage the locking feature from first portion 150q and / or second portion 152q when third portion 392q is rotated about an axis of the system. Some examples of trigger mechanisms are described in connection with FIGS. 92-104.

[0493] 87 illustrates a side cross-sectional view of system 104q after first portion 150q and second portion 152q have been unlocked. As can be seen in FIG. 87, first spring 402q drives first portion 150q in a distal direction as first spring 402q expands. The movement of first portion 150q also urges needle hub 162q (as well as on-skin component 134q coupled to needle hub 162q) in a distal direction, coupling on-skin component 134q to base 128q, compressing second spring 234q, and driving needle 156 distally past the distal end of system 104q. At or about the same time (e.g., immediately prior to, in unison with, or subsequently to) the needle hub 162q reaches the distal insertion position illustrated in FIG. 87, an end of the release feature 160q contacts the contact interface feature 170q of the second portion 152q, causing the release feature 160q to compress inwardly (toward the central axis of the system 104q), unlocking the needle hub 162q from the first portion 150q and activating the now-energized second spring 234q. In some embodiments, the interference feature 170q is a proximally-facing interference feature. In other embodiments, the interference feature 170q is a distally-facing interference feature (not shown).

[0494] Activation of second spring 234q by a user or mechanism biases needle hub 162q in a proximal direction while on-skin component 134q, which is coupled to base 128q, remains in a deployed distal position. FIGURE 88 illustrates a side cross-sectional view of system 104q with on-skin component 134q in a deployed position and needle hub 162q retracted in a proximal position.

[0495] 89-91 illustrate another embodiment of a system 104r for applying an on-skin sensor assembly to a recipient's skin. The system 104r illustrated with reference to FIGS. 89-91 is contemplated to provide a predictable spring displacement of the first spring 402r since the first spring is already compressed, thereby helping to ensure proper needle insertion into the user's skin. Additionally, it is contemplated that the compressed second spring 234r provides a predictable spring displacement and also helps to ensure proper retraction of the needle from the user's skin. In some embodiments, a system incorporating pre-energized insertion and retraction springs can provide effective and reliable insertion and retraction while requiring a lower amount of user-applied force than, for example, a system in which one or both of the insertion and retraction springs are in a substantially unenergized state prior to deployment, making such a configuration more convenient for at least some users. The system 104r includes a number of items similar to the features of the embodiment illustrated in FIGS. 76-79 (e.g., a nested assembly 132r including a first portion 150r, a second portion 152r, and a third portion 392r, a needle hub 162r, a first spring 402r, a second spring 234r, an on-skin component 134r, and a base 128r). As illustrated in FIGS. 89-91, the first spring 402r and the second spring 234r are both pre-compressed. In the system 104r, the first spring 402r is formed separately from and operably coupled to the third portion 392r. The second spring 234r is formed separately from and operably coupled to the needle hub 162r. The first spring and / or the second spring may be constructed of metal. Alternatively, in some embodiments, one or both of the first spring and the second spring can be integrally formed with a portion of the applicator assembly.

[0496] FIG. 89 illustrates a side cross-sectional view of the system 104r in a rest position where the first spring 402r and the second spring 234r are both pre-energized (e.g., sufficiently compressed to drive the needle insertion and retraction process). In the rest state illustrated in FIG. 89, the first portion 150r is locked to the second portion 152r to prevent proximal or distal movement of the first portion 150r relative to the second portion 152r. The first portion 150r and the second portion 152r can be locked together in any suitable manner, for example, by cooperating releasable locking features coupled to or forming part of the first portion 150r and the second portion 152r (e.g., locking features described in connection with FIGS. 80-83, or other suitable locking features). The needle hub 162r is also releasably locked to the first portion 150r. The needle hub 162r can be locked to the first portion 150r in any suitable manner, for example, by a feature of the first portion 150r configured to engage or compress the release feature 160r of the needle hub 162r. The third portion 392r and the second portion 152r are also locked together to prevent relative movement of the third portion 392r and the second portion 152r in at least the axial direction. The third portion 392r and the second portion 152r can be locked together in any suitable manner, for example, by a locking feature (not shown in FIGS. 89-91 ) that can be coupled to or form part of the third portion 392r and the second portion 152r. In the rest state illustrated in FIG. 89 , the on-skin component 134r is disposed in a proximal start position such that the distal end of the needle 156 is disposed between the proximal and distal ends of the system 104r.

[0497] To trigger deployment of the system 104r, the locking feature connecting the first portion 150r to the second portion 152r can be unlocked, uncoupling the two portions, thereby releasing or activating the first spring 402r. FIG. 90 illustrates a side cross-sectional view of the system 104r after the first portion 150r and the second portion 152r have been unlocked. As can be seen in FIG. 90, the first spring 402r drives the first portion 150r in a distal direction as the first spring 402r expands or compresses. The movement of the first portion 150r also urges the needle hub 162r (as well as the on-skin component 134r connected to the needle hub 162r) in a distal direction until the on-skin component 134r is coupled to the base 128r and the needle 156 reaches a distal insertion position beyond the distal end of the system 104r. At or approximately simultaneously (e.g., immediately prior to, in unison with, or subsequently to) the needle hub 162r reaches the distal insertion position illustrated in FIG. 87, the end of the release feature 160r contacts a corresponding interface feature 170r of the second portion 152r, causing the release feature 160r to compress inward (toward the central axis of the system 104r), unlocking the needle hub 162r from the first portion 150r and releasing or activating the second spring 234r.

[0498] Activation of the second spring 234r drives the needle hub 162r in a proximal direction while the on-skin component 134r coupled to the base 128r remains in a deployed distal position. FIG. 91 illustrates a side cross-sectional view of the system 104r with the on-skin component 134r in a deployed position and the needle hub 162r retracted in a proximal position. From this configuration, the system 104r can be removed and separated from the deployed on-skin component 134r and base 128r.

[0499] 92-100 illustrate yet another embodiment of a system 104s for applying an on-skin sensor assembly to the skin of a recipient with safety features to prevent accidental ejection of the sensor insertion device. The system 104s includes a number of items similar to the features of the embodiment illustrated in FIGS. 76-79 (e.g., a nested assembly 132s including a first portion 150s, a second portion 152s, and a third portion 392s, a needle hub 162s, a first spring 402s, a second spring 234s, an on-skin component 134s, and a base 128s). In the system 104s, the first spring 402s can be formed separately from and operably coupled to the third portion 392s. The second spring 234s can be formed separately from and operably coupled to the needle hub 162s. The first spring and / or the second spring can be constructed of metal. Alternatively, in some embodiments, either or both of the first spring and the second spring can be integrally formed with a portion of the applicator assembly.

[0500] FIG. 92 illustrates a side view of the system 104s in a quiescent state, with the first spring 402s in an unstressed and unenergized state, but the second spring 234s already energized (e.g., compressed). The system 104s includes a cocking mechanism 702 that can energize (compress) the first spring 402s without automatically triggering the deployment of the first portion 150s or the activation of the first spring 402s. The system 104s also includes a trigger button 720 configured to activate the first spring 402s after the system is cocked. FIG. 93 illustrates a side view of the applicator system 104s after it has been cocked, but before it has been triggered.

[0501] 94 illustrates a cross-sectional perspective view of the system 104s in a resting state showing the first spring 402s in a substantially uncompressed state. The cocking mechanism 702 includes a pair of proximally extending lever arms 704, each having a radially extending angled tab 706. In some embodiments, the lever arms 704 can be integrally formed with the second portion 152s, as shown in FIG. 94, while in other embodiments, the lever arms 704 can be separate from and operably coupled to the second portion 152s. In the resting state illustrated in FIG. 94, the angled tabs 706 extend through a distal opening 708 of the third portion 392s to prevent proximal movement of the third portion 392s relative to the second portion 152s. The angled tab 706 is also configured to prevent distal movement of the third portion 392s relative to the second portion 152s unless and until a sufficient amount of force is applied to the third portion 392s to deform the angled tab 706 and deflect the angled tab 706 and the lever arm 704 inwardly, as shown in FIG. 95.

[0502] As sufficient force is applied to the third portion 392s in a distal direction (e.g., by a user's hand or thumb), the angled tab 706 deflects inwardly and disengages from the distal opening 708, allowing the third portion 392s to move distally relative to the second portion 152s. This allows the user to compress and energize the first spring 402s. As illustrated in FIG. 96, when the third portion 392s has reached a distal position sufficiently to compress the first spring 402s sufficiently to drive the sensor into the recipient's skin, the angled tab 706 engages the proximal opening 710 of the third portion 392s to lock the position of the third portion 392s relative to the second portion 152s. The angled tab 706 can be configured to generate a "click" sound when engaging the proximal opening 710 to prevent proximal movement of the third portion 392s relative to the second portion 152s, so that the user can feel and / or hear when the parts are engaged. In the configuration illustrated in FIG. 96, the system 104s is energized when the third portion 392 is in the cocked position. The system 104s is ready to deploy the sensor, but will not deploy until further action is taken by the user.

[0503] 97 illustrates a side cross-sectional view of the system 104s in a cocked but untriggered state. In this state, the first portion 150s is locked to the second portion 152s to prevent proximal or distal movement of the first portion 150s relative to the second portion 152s. The first portion 150s and the second portion 152s can be locked together in any suitable manner, such as by cooperating releasable locking features 396s and 398s that are releasably coupled to or form part of the first portion 150s and the second portion 152s. The trigger button 720 includes a distally extending protrusion 722 configured to cooperate with the unlocking feature 406s of the locking feature 396s to uncouple the first portion 150s from the second portion 152s when pressed sufficiently distally by a user. The trigger button 720 may be operably coupled to the third portion 392s, as illustrated in Figures 92-100, or may be formed integrally with the third portion, for example as a lever arm formed in a proximal or side portion of the third portion. In some embodiments, the trigger button may be located on the top of the system (such that application of a force in a distal direction triggers and activates the system) or on the side of the system (such that application of a force in a radially inward direction, perpendicular to the direction of needle deployment, triggers and activates the system).

[0504] 98 illustrates a side cross-sectional view of the system 104s in an energized state where the trigger button 720 is sufficiently depressed to cause the protrusions 722 to flex the locking features 396s radially inwardly, disengaging the locking features from the apertures 398s and disengaging the first portion 150s from the second portion 152s. As illustrated in FIG. 99, depressing the trigger button 720 activates the first spring 402, pushing the first portion 150s and needle hub 162s, along with the on-skin components coupled thereto, in a distal direction until the on-skin component 134s is coupled to the base 128s. At or about the same time (e.g., immediately prior to, in unison with, or subsequently to) the needle hub 162s reaching the distal insertion position illustrated in FIG. 99, corresponding release features of the needle hub 162s and first portion 150s can be engaged (e.g., via a release feature described in any of FIGS. 76-91 or any other suitable release feature), unlocking the needle hub 162s from the first portion 150s and releasing or activating the second spring 234s. Activation of the second spring 234s biases the needle hub 162s in a proximal direction.

[0505] Fig. 100 illustrates a side cross-sectional view of the applicator system of Fig. 92 with the on-skin component 134s in a deployed position and the needle hub 162s retracted to a proximal position. As the needle hub 162s retracts to a proximal position, the on-skin component 134s decouples from the needle hub 162s and remains in the deployed position and coupled to the base 128s. From this configuration, the remainder of the system 104s can be removed and separated from the deployed on-skin component 134s and base 128s.

[0506] Any of the features described in the context of any of Figures 61-99 may be applied to all aspects and embodiments identified herein. For example, an embodiment described in the context of Figures 61-64 may be combined with an embodiment described in the context of Figures 1-60 and 65-70. As another example, any of the embodiments described in the context of Figures 92-109 may be combined with any of the embodiments described in the context of Figures 1-60 and 65-91 and 110-143. Furthermore, any of the features of an embodiment may be combined partially or wholly independently with other embodiments described herein, for example, one, two, or more than two embodiments may be combined in whole or in part. Furthermore, any of the features of an embodiment may be optional with respect to other aspects or embodiments. Any aspect or embodiment of a method may be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system may be configured to perform a method of another aspect or embodiment.

[0507] Trigger mechanism and safety lock In some embodiments, the application of sufficient force to sufficiently energize the first spring to drive insertion of the sensor also serves to activate the first spring, hi other embodiments, energizing the first spring can be decoupled from the activation of the first spring, requiring separate actions by the user to energize (e.g., compress) the first spring and part of triggering deployment of the system.

[0508] For example, the embodiment illustrated in Figures 92-100 includes a trigger mechanism in the context of a user-energized actuator. In such an embodiment, the user first cocks the system 104s to energize the first spring 402s, and then, in a separate action, triggers activation of the first spring 402s using the trigger button 720. The locking feature is easy to release by the user, and when combined with the trigger mechanism, allows for one-handed use.

[0509] In some embodiments, the actuator or insertion spring is already energized when the system is at rest. In these embodiments, a trigger mechanism, such as the trigger mechanism described in the context of Figures 92-100, can be used to activate the already energized insertion spring without any action by the user to energize the spring.

[0510] Figure 101 illustrates a side view of one such applicator system 104t having a side trigger button 730. System 104t may be configured substantially similar to system 104q illustrated in the range of situations of Figures 86-88 or system 104r illustrated in the range of situations of Figures 89-91, with like reference numerals indicating like parts. As can be seen in Figure 101, trigger button 730 is operably coupled to third member 392t.

[0511] FIG. 102 illustrates another side view of the system 104t, showing the first portion 150t and the third portion 392t in cross-section to illustrate the trigger mechanism. As can be seen in FIG. 102, the trigger button 730 includes a protrusion 732 that extends radially inward toward a central axis of the system 104t. The protrusion 732 is radially aligned with the locking feature 396t of the first portion 150t. When a user exerts a lateral (e.g., radially inward) force on the trigger button 730, the protrusion 732 urges the locking feature 396t radially inward, disengaging it from the ledge feature 398t of the second portion 152t (which may be configured, for example, similar to the ledge locking feature 398p illustrated in FIGS. 84 and 85) and actuating the first spring 402t. In other embodiments, the locking features 396, 398 can include cooperating structure of a key / keyway mechanism that is configured to release when the features 396, 398 are in a particular orientation relative to one another (e.g., using a radially applied force, an axially applied force, a torsional or rotational force, or other type of actuation).

[0512] FIG. 103 illustrates a side view of another applicator system 104u having an integrated side trigger button 730. The system 104u may be configured substantially similar to the system 104q illustrated in the context of FIGS. 86-88 or the system 104r described in the context of FIGS. 89-91, with like reference numerals referring to like parts. As seen in FIG. 103, the trigger button 740 is a distally extending lever arm integrally formed on the third member 392u. FIG. 104 illustrates another side view of the system 104u showing the first portion 150u and the third portion 392u in cross section to better illustrate the trigger mechanism. As seen in FIG. 104, the trigger button 740 is radially aligned with a radially extending tab 742 on the first portion 150u. The tab 742 is connected to the locking feature 396u via an elongated member 394u acting as a lever arm. In some embodiments, the tab 742, the locking feature 396u, and the elongate member 394u are integrally formed together. When a user exerts a lateral (e.g., radially inward) force on the trigger button 740, the button 740 pushes the tab 742 radially inward, disengaging the locking feature 396u from engagement with the locking feature 398u of the second portion 152u and actuating the first spring 402u.

[0513] Trigger mechanisms such as those described in any of Figures 92-104 can be used in embodiments with a pre-energized actuator or insertion spring, as well as in embodiments with a user-energized actuator or insertion spring.

[0514] In some embodiments, the sensor inserter system can include a safety mechanism configured to prevent premature energization and / or activation of the insertion spring. FIGS. 105-109 illustrate one such system 104v incorporating a safety lock mechanism 750. FIG. 105 illustrates a perspective view of the system 104v. The system 104v can be configured substantially similar to any of the systems 104m, 104n, 104p illustrated in the context of FIGS. 71-87, with like reference numerals indicating like parts. The safety lock mechanism 750 includes a release button 760, which can be integrally formed with the third portion 392v shown in FIG. 105 (similar to the trigger button 740 described in connection with FIGS. 103-104) or operably coupled to the third portion 392v. In system 104v, release button 760 comprises a lever arm integrally formed on the side of third portion 392v, although other configurations (e.g., a top button) are contemplated. The release button can be configured to protrude radially from the side or top of the third portion, or can be configured with an outer surface that is flush with the surrounding surface of third portion 392v.

[0515] FIG. 106 illustrates a cross-sectional perspective view of a portion of the system 104v with the safety mechanism 750 in a locked configuration and the first spring 402v in an unenergized state. The safety mechanism 750 includes a proximally extending locking tab 752 on the second portion and an inwardly extending overhang (or undercut) 754 on the third portion 392v. In the locked configuration illustrated in FIG. 106, the tab 752 is flexed radially outward and its proximal end is restrained by the overhang 754, preventing distal movement of the third portion 392v relative to the second portion 152v, thus preventing energization of the spring 392v. The release button 760 includes an inwardly extending protrusion 758 in radial alignment with a portion of the tab 752. A lateral (e.g., radially inward) force applied to the release button 760 may push the tab 752 radially inward, causing a proximal end of the tab 752 to slide against the angled surface 756 of the overhang 754 and disengage from the overhang 754, thereby releasing the tab 752 to an unstressed configuration as shown in FIG. 108. Once the tab 752 is released, the third portion 392v may be moved distally relative to the second portion 152v, for example, to energize the first spring 402v. In some embodiments, as illustrated in FIG. 109, the tab 752 may be configured to prevent further distal movement of the third portion 392v beyond a desired threshold, for example, by abutting a distally facing surface 762 of the third portion 392v.

[0516] Although safety lock mechanism 750 is illustrated in the context of a system configured to be energized by a user, in some embodiments, pre-energized systems can also employ safety lock mechanisms, for example to prevent premature triggering or activation of an already-energized spring.

[0517] In some embodiments, the locking and unlocking (and / or coupling and uncoupling) of the components of the sensor inserter assembly may follow the following sequence: The sensor inserter assembly begins in a quiescent state with the third portion 392 locked to the first portion 150, the first portion 150 locked to the second portion 152, and the sensor module 134 coupled to the first portion 150 (optionally via the needle hub 162). Prior to energizing or triggering the insertion spring 402, the third portion 392 is unlocked from the first portion 150 and / or the second portion 150. The insertion spring 402 is then energized by distal movement of the third portion 392, if not already energized. The third portion 392 is then locked to the second portion 152. The first portion 150 is then unlocked from the second portion 152 to activate the insertion spring 402. When the insertion spring 402 is deployed, it couples the sensor module 134 to the base 128. The first portion 150 (and / or needle hub 162) then releases the sensor module 134 and the second portion 152 releases the base 128. In some embodiments, the locations of the various locking and unlocking (and / or coupling and uncoupling) structures along the axis of the assembly are optimized to allow this sequence to be the only sequence possible. (Some embodiments use a different locking and unlocking operating sequence.)

[0518] Systems such as those illustrated in Figures 92-109 provide a reliable trigger mechanism to release the insertion spring when it is in a loaded state. Such systems are contemplated to provide several advantages to the user, including ease of firing, one-handed firing (by allowing the user to hold both sides of the insertion device and fire the insertion device using the same hand). A system with a top trigger can provide a smaller width profile than a system with a side button, while requiring less dexterity from the user.

[0519] Cancellation after deployment In some embodiments, the sensor inserter system is configured to move the on-skin component (e.g., the sensor module 134, the sensor assembly (e.g., comprising a sensor, electrical contacts, and optionally a sealing structure), a sensor module and base combination, an integrated sensor module and transmitter, an integrated sensor module and transmitter and base, or any other component...

Claims

[Claim 1] 1. A system for applying an on-skin sensor assembly to a skin of a recipient, comprising: a telescoping assembly having a first portion configured to move distally relative to a second portion along a path from a proximal start position to a distal position; a sensor module coupled to the first portion, the sensor module including a sensor module housing, a sensor, electrical contacts, and an encapsulant; a base coupled to the second portion to protrude from a distal end of the system, the base comprising a sensor insertion opening and an adhesive configured to couple the sensor module to the skin, and wherein moving the first portion to the distal position couples the sensor module to the base; the sensor module housing includes a channel; The sensor, a first section configured to be inserted into the recipient's body during a sensor session, the first section comprising at least one electrode; a second section configured to remain outside the recipient's body during the sensor session, the second section being mechanically coupled to the sensor module housing, with at least a portion of the second section of the sensor located within the channel; The second section of the sensor is a first portion extending in a first direction along the channel of the sensor module housing; a second portion extending through the sensor insertion opening in the base in a second direction different from the first direction.

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