Transcutaneous analyte sensor systems and methods

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] Incorporation by Interaction of Related Applications Any claim of priority or any amendment thereto identified in the application data sheet is incorporated herein by reference under 37 CFR 1.57. This application claims the benefit of U.S. Provisional Application No. 62 / 272,983, filed Dec. 30, 2015, and U.S. Provisional Application No. 62 / 412,100, filed Oct. 24, 2016. Each of the foregoing applications is incorporated herein by reference in its entirety and each of them is hereby expressly made a part of this specification.

[0002] The various embodiments disclosed herein relate to measuring an analyte of a person. Certain embodiments relate to systems and methods for applying a transdermal analyte measurement system to a person.

Background Art

[0003] Diabetes mellitus is a disorder in which the pancreas cannot produce sufficient insulin (type I or insulin-dependent), and / or insulin is ineffective (type 2 or non-insulin-dependent). In a diabetic state, the sufferer has hyperglycemia, which can cause a series of physiological disorders associated with microvascular deterioration, such as renal failure, skin ulcers, or bleeding into the vitreous of the eye. Hypoglycemic reactions (hypoglycemia) can be caused by inadvertent overdosage of insulin, or extreme exercise or inadequate food intake after normal dosing of insulin or glucose-lowering agents.

[0004] Conventionally, a person suffering from diabetes carries a self - monitoring blood glucose monitor, which typically requires an uncomfortable finger - prick method. Due to the lack of comfort and convenience, a person with diabetes usually only measures glucose levels 2 - 4 times a day. Unfortunately, since such time intervals are too widely dispersed, a person with diabetes may be too late to know about hyperglycemic or hypoglycemic conditions, sometimes leading to dangerous side effects. Glucose levels can alternatively be continuously monitored by a sensor system including a sensor assembly on the skin. The sensor system can have a transmitter that transmits measurement data to a receiver, which can process and display information based on the measured values.

[0005] The process of applying the sensor to a person is important for making such a system effective and user - friendly. This application process enables the sensor assembly to be attached to the person in a state where the sensor assembly can sense glucose level information, communicate the glucose level information to the transmitter, and transmit the glucose level information to the receiver.

[0006] The analyte sensor can be placed into subcutaneous tissue. The user can activate an applicator to insert the analyte sensor into its functional location. This transdermal insertion can lead to incomplete sensor insertion, improper sensor insertion, needle exposure, or unnecessary pain. Therefore, there is a need for a system that makes transdermal sensor insertion more reliable while being user - friendly and relatively less painful. Summary of the Invention

[0007] The various systems and methods described herein enable reliable, simple, and minimally painful transdermal insertion of analytes. Some embodiments are systems for applying a sensor assembly on the skin to a recipient's skin. The system has a nested assembly having a first portion configured to move distally relative to a second portion along a path from a proximal starting position to a distal position, a sensor module coupled to the first portion, the sensor module including a sensor, an electrical contact, and a seal, and / or a base coupled to the second portion so as to protrude from a distal end of the system. The base can comprise an adhesive configured to couple the sensor module to the skin. Moving the first portion to the 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 combinable independently of any of the aspects and embodiments specified 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 combinable independently of any of the aspects and embodiments specified 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 causes the sensor to be coupled to the base by moving the first portion distally relative to the second portion.

[0010] In some embodiments (i.e., optional and combinable independently of any of the aspects and embodiments specified herein), the sensor can be coupled to the sensor module while the first portion is positioned at the proximal starting position.

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

[0012] In some embodiments, the base comprises a distal protrusion having a first aperture. The distal protrusion can be configured to reduce the resistance of the skin to penetration. The sensor can pass through the first aperture of the distal protrusion.

[0013] In some embodiments, the needle having a slot passes through the first aperture of the distal protrusion. A portion of the sensor can be positioned within the slot such that the needle is configured to move distally relative to the base without displacing the portion of the sensor from the slot.

[0014] In some embodiments, the distal protrusion is convex such that the distal protrusion applies tension to the skin while the first portion moves distally relative to the second portion to prepare the skin for piercing. The distal protrusion can have a dome-like shape.

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

[0016] In some embodiments, the adhesive covers at least a majority of the distal protrusion. The adhesive can cover 0 percent, at least 30 percent, at least 70 percent, and / or less than 80 percent of the distal protrusion. The distal protrusion can protrude at least 0.5 millimeter, 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 a proximal starting position and is positioned at least 3 millimeters and / or at least 5 millimeters from the base. The system can be configured to couple the sensor module to the base by moving the first portion to a distal position.

[0018] In some embodiments, the sensor is already coupled to the sensor module while the first portion is positioned in the proximal starting position. For example, the sensor can be coupled to the sensor module at the factory (e.g., before the user unseals the sterilization 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 the sensor module. The sensor module can be fixed relative to the first portion during a first portion of the path, and the base can be fixed relative to the second portion. The system can be configured to move the first portion distally relative to the second portion during a 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 comprises a vertical central axis oriented from a proximal end to a distal end of the system. The sensor module can comprise a first flex arm that is horizontally oriented and coupled to the base. The first flex arm can extend from an outer peripheral portion of the sensor module.

[0021] In some embodiments, the base comprises a first proximal protrusion coupled to the first flex arm to couple the sensor module to the base. The first horizontal locking protrusion can be coupled to the 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 to bend the first flex arm to move the first part of the nested assembly to the distal position, enabling the first horizontal locking protrusion to move distally relative to the second horizontal locking protrusion.

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

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

[0024] In some embodiments, the first horizontal locking protrusion is coupled to the end portion of the first flexible arm, the second horizontal locking protrusion is coupled to the first distal protrusion of the sensor module, and the second horizontal locking protrusion is positioned distally below the first horizontal locking protrusion to secure the sensor module to the base. The system can be configured to bend the first flex arm to move the first part of the nested assembly to the distal portion, enabling 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 the second flex arm of the base. The first distal protrusion can be positioned on the 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 while the first portion is in a proximal starting position and latch-engage over the sensor module to removably 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 starting position.

[0027] In some embodiments, the sensor module 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 module to the base by moving the first portion distally relative to the second portion.

[0028] In some embodiments, the system includes 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 removably coupled to the first portion with a first vertical retention strength. The sensor module can include a third flex arm coupled to the 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 holding strength is greater than the first vertical holding strength such that when the sensor module is coupled to the base, it overcomes the first and second flex arms of the first portion by continuously pushing the first portion distally, to remove the sensor module from the first portion. The third flex arm can extend from the outer peripheral portion of the sensor module.

[0030] In some embodiments, the base projects from the distal end of the system while the first portion of the nested assembly is positioned in the proximal starting position, and the sensor is positioned remotely relative to the base such that the system is configured to couple the sensor to the base by moving the first portion distally relative to the second portion. The base can comprise a first radially projecting portion releasably coupled to the second radially projecting portion of the second portion of the nested assembly with the first vertical holding strength.

[0031] In some embodiments, the first radially projecting portion projects inwardly and the second radially projecting portion projects outwardly. The system can be configured to move the first portion to the distal portion to move the second radially projecting portion relative to the first radially projecting portion to remove the base from the nested assembly.

[0032] In some embodiments, the first portion of the nested assembly comprises a first arm projecting distally, the second portion of the nested assembly comprises a second flex arm projecting distally, and the system is configured to move the first portion along a path from the proximal starting position to the distal position to deflect the second flex arm by the first arm, thereby enabling removal of the second flex arm from the base and decoupling of the base from the nested assembly. When the first portion is in the proximal starting position, the first arm of the first portion can be at least partially vertically aligned with the second flex arm of the second portion such that as the first portion moves to the distal position, the first arm deflects the second flex arm.

[0033] In some embodiments, when the first portion is in the proximal starting position, at least a section of the first arm is positioned directly over the second flex arm such that as the first portion moves to the distal position, the first arm is capable of deflecting the second flex arm.

[0034] In some embodiments, the second flex arm comprises a first horizontal protrusion, and the base comprises a second horizontal protrusion that is latch - engaged 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 a sensor to the base at a first position and is configured to remove the base from the nested assembly at a second position that is distal to the first position.

[0036] In some embodiments, the third flex arm couples the sensor to the base at a first position and removes the base from the second flex arm at a second position, the second position being distal to the first position such that the system is configured to fix the base to the nested assembly after the sensor is fixed to the base.

[0037] In some embodiments, the base projects from the distal end of the system while the first part of the nested assembly is in the proximal starting position and the sensor is positioned remotely relative to the base. The system can further comprise a spring configured to store the needle. The needle can be configured to facilitate insertion of the sensor into the skin. When the first part is in the proximal starting position, the spring can be in a first compressed state. The system can be configured such that moving the first part distally from the proximal starting position further increases the compression of the spring. The first compressed state positions the first and second parts in a tensioned state.

[0038] In some embodiments, the system is configured to apply a skin sensor assembly to the skin of a recipient (i.e., a person). The system can include a nested assembly having a first part configured to move distally relative to a second part along a path from a proximal starting position to a distal position, a sensor coupled to the first part, and / or a latch configurable to prevent the needle from moving proximally relative to the first part. 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 part is releasably fixed in the proximal starting position by a fixing mechanism that prevents the first part from moving distally relative to the second part. The system can be configured such that moving the first part distally relative to the second part (e.g., moving the first part to the distal position) releases the latch, thereby causing the needle to be retracted proximally into the system. The fixing mechanism can be an interference portion between the first and second parts of the nested assembly.

[0040] In some embodiments, the first force profile is measured along a path. The first force profile can comprise a first magnitude that corresponds to overcoming a fixation mechanism, a third magnitude that corresponds to releasing a latch, and a second magnitude that corresponds to an intermediate portion of the path that is distal to overcoming the fixation mechanism and proximal to releasing the latch.

[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 between the intermediate portions of the path to enable an appropriate needle velocity (e.g., a sufficiently high needle velocity) when the needle first penetrates 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 the start of the sensor insertion cycle unless the 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 path is distal to overcoming the fixation mechanism and proximal to releasing the latch. The system can further comprise a second force profile that corresponds to the intermediate portion of the path. In response to compressing a spring configured to allow the system to store the needle into the nested assembly, the proximal millimeter of the second force profile can have an average force that is lower than the average force of the distal millimeter of the second force profile.

[0044] In some embodiments, the first force profile is measured along a path. The first force profile can comprise a first average magnitude that corresponds to moving distally past the proximal half of the fixation mechanism, and a second average magnitude that corresponds to moving distally past the 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 starting a sensor insertion cycle (e.g., driving the needle and / or sensor to the intended insertion depth) unless the user applies sufficient force to complete the sensor insertion cycle.

[0045] In some embodiments, a first force peak (corresponding to 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, the first force profile is measured along a path. The first force profile can comprise a first magnitude that corresponds to overcoming the fixation mechanism, and a subsequent magnitude that corresponds to stopping 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 comprise a radially outward protrusion extending from a second portion. The radially outward protrusion can be positioned proximal to the proximal end of the second portion while the nested assembly is in the proximal starting position. The radially outward protrusion can be configured to deform the first portion into an elliptical shape to enable the first portion to move distally relative to the second portion.

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

[0049] In some embodiments, the needle is removably coupled to the first portion by a needle holder configured to resist distal movement of the first portion relative to the second portion. The fixation mechanism can comprise a flexible arm of the second portion. The flexible arm can be removably coupled to the needle holder to removably fix the first portion to the second portion in a proximal starting position.

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

[0051] In some embodiments, the fixation mechanism comprises a magnet that removably couples the first portion to the second portion while the first portion is in the proximal starting position. The magnet can attract a metallic element coupled to the first or second portion of the nested assembly.

[0052] In some embodiments, an 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, the on-skin sensor system is configured for transcutaneous glucose monitoring of a recipient. The system can include a sensor module housing, a first flex arm, a first section configured for subcutaneous sensing, and a second section mechanically coupled to the sensor module housing. The sensor can have 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 includes a spring. The spring can include a conical portion and / or a helical portion.

[0055] In some embodiments, the sensor module housing includes at least two proximal protrusions positioned around the outer perimeter of the spring. The proximal protrusions can be configured to assist in orienting the spring. A segment 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 couple the base to the recipient's skin.

[0057] In some embodiments, the proximal protrusions orient the spring such that coupling the electronic device unit to the base presses the spring against a first electrical contact of the electronic device unit and a second electrical contact of the sensor, electrically coupling the sensor to the electronic device unit.

[0058] In some embodiments, the sensor module housing comprises a first flexure arm that is horizontally oriented and coupled to the base. The first flexure arm can extend from the outer peripheral portion of the sensor module housing. The base can comprise a first proximal protrusion coupled to the first flexure arm for coupling the sensor module housing to the base.

[0059] In some embodiments, the electrical interconnection comprises a leaf spring, which can comprise one or more metal layers. The leaf spring can be a cantilever spring.

[0060] In some embodiments, the sensor module housing comprises a proximal protrusion having a channel in which at least a portion of a second section of the sensor is positioned. The channel can position a 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 electronic device 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 to electrically couple with the electronic device unit.

[0063] In some embodiments, the seal is configured to prevent fluid entry 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 skin of the recipient.

[0064] In some embodiments, the proximal protrusion orients the spring to press the electronic device unit against the first electrical contact of the electronic device unit and the second electrical contact of the sensor, electrically coupling the sensor to the electronic device unit so as to couple the electronic device unit to the base. The proximal height of the seal can be made higher than the proximal height of the leaf spring so that the seal contacts the electronic device unit before the electronic device unit contacts the leaf spring.

[0065] In some embodiments, the sensor module housing comprises a first flexure arm that is horizontally oriented and coupled to the base. The first flexure arm can extend from an outer peripheral portion of the sensor module housing. The base can comprise a first proximal protrusion coupled to the first flexure arm to couple the sensor module housing to the base.

[0066] In some embodiments, the sensor module housing comprises a channel in which at least a portion of a second section of the sensor is positioned. The distal portion of the leaf spring can be positioned within the channel such that the proximal portion of the leaf spring protrudes proximally from the channel. The sensor module housing can comprise a groove that intersects the channel. The leaf spring can comprise 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 comprise a first flexure arm that is horizontally oriented and coupled to the base. The first flexure arm can extend from an outer peripheral portion of the sensor module housing. The base can comprise a first proximal protrusion coupled to the first flexure arm to couple the sensor module housing to the base.

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

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

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

[0071] In some embodiments, a system for applying a skin sensor assembly to a recipient's skin includes a nested assembly having a first portion configured to move distally relative to a second portion along a path from a proximal starting position to a distal position, a sensor coupled to the first portion, and a base including an adhesive configured to couple the sensor to the skin. The nested 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. At the proximal starting position of the nested assembly, the first portion can latch to the second portion. The system can be configured such that moving the third portion distally relative to the second portion unlatch the first portion from the second portion.

[0073] In some embodiments, a first proximal protrusion having a first hook passes through a first hole in the second portion to latch the first portion to the second portion. The third portion can comprise a first distal protrusion. The system can be configured such that moving the third portion distally relative to the second portion engages the lamp portion to bend the first proximal protrusion to unlatch 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 by moving the first portion distally relative to the second portion.

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

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

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

[0078] In some embodiments, the system includes a second protrusion that engages with at least one aperture of 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, and the compressed first spring enables the first portion to push against the second portion, pushing at least a portion of the sensor out of the distal end of the system and triggering a needle storage mechanism to enable the second spring to store the needle.

[0080] In some embodiments, a system is provided for applying a skin assembly to a recipient's skin. Advantageously, the system includes a sensor inserter assembly having a needle assembly, a sensor module, a base, an actuating member, and a storage member, the sensor inserter assembly having an initial configuration in which at least the sensor module is disposed in a proximal starting position, and the sensor inserter assembly further having a deployed configuration in which at least the sensor module and the base are disposed in a distal application position. Preferably, the actuating member is configured to move the needle assembly from the proximal starting position to a distal insertion position when activated, and the storage member is configured to move the needle assembly from the distal insertion position to a proximal storage position when activated.

[0081] The sensor module can include one sensor and a plurality of electrical contacts. In the initial configuration, the sensor can 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 can 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 actuating member can include a spring. In an initial configuration, the spring can be in a non-stressed state. In an alternative embodiment, in the initial configuration, the spring is in a compressed state.

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

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

[0085] In still other embodiments, the storage member includes a spring. The spring can be integrally formed with the needle assembly. The spring can operably couple the assembly to the needle. In an initial configuration, the spring can be in a non-stressed state. In other embodiments in an initial configuration, the spring is in a compressed state.

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

[0087] In some embodiments, the sensor inserter assembly can further include a third portion that is 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 movement of the first portion distally relative to the second portion until the interengagement structure is disengaged. Advantageously, disengaging the interengagement structure can activate the actuating member. In other embodiments, the interengagement structure can include a proximally extending tab of the first portion and a receptacle of the second portion configured to receive the proximally extending tab. Optionally, the sensor inserter assembly can include a release member configured to disengage the interengagement structure. The release member can have a distally extending tab of the third portion.

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

[0090] In certain embodiments, the sensor insertion machine assembly can include an engagement structure configured to prevent proximal movement of the needle assembly at least when the needle assembly is in a distal insertion position. The engagement structure can have a radially extending release feature of the needle assembly and an inner surface of a first portion configured to compress the release feature. Optionally, the sensor insertion machine assembly can include a disengagement member configured to disengage the engagement structure of the first portion and the needle assembly. The disengagement member can include an inner surface of a second portion configured to further compress the release feature. Advantageously, the system can further include a trigger member configured to activate an actuating member. The trigger member can be operably coupled to a third portion. The trigger member can be integrally formed with the third portion. The trigger member can include a proximally extending button. Alternatively, the trigger member can include a radially extending button. The trigger member can be configured to disengage the engagement structures of the first and third portions.

[0091] In some embodiments, the system can further include a releasable locking member configured to prevent activation of the actuating member until the locking member is released. The releasable locking member can 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 can include a proximally extending tab of the first portion and a latch feature of the third portion configured to receive the proximally extending tab. Advantageously, the releasable locking member is configured to prevent energization of the sensor insertion machine assembly. In other aspects, the releasable locking member is configured to prevent energization of the actuating member.

[0092] The embodiment can further include a system for applying a skin component to a recipient's skin. The system includes a sensor inserter assembly having a skin component movable distally from at least a proximal position to a distal position, a first fixing feature configured to removably fix the skin component at the proximal position, a second fixing feature configured to fix the skin component at the distal position, and a first resistance configured to prevent proximal movement of the skin component at least when the skin component is at the distal position.

[0093] The first resistance feature can be configured to prevent proximal movement of the skin component when the skin component is fixed at the distal position. In some embodiments, the first fixing feature is configured to removably fix the skin component to the needle assembly. The skin component can have a sensor module. The sensor module can include one 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 a first configuration.

[0094] In some embodiments, the skin component includes a base. The skin component can include a transmitter. The second fixing feature can be configured to fix the skin component to a second skin component.

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

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

[0098] The system can further include a pusher configured to move the component on the skin from a proximal position to a distal position. Optionally, the system can further include a release feature configured to release the pusher from the component on the skin at least after the component on the skin reaches the distal position. The release feature can have a frangible portion of the pusher. Optionally, the release feature comprises a frangible portion of the component on the skin.

[0099] The system can further comprise a sensor assembly configured to couple to the component on the skin, a third securing feature configured to removably secure the sensor assembly in a proximal position, and a fourth securing feature configured to secure the sensor assembly to the component on the skin.

[0100] Any of the features of the aspects shown herein are applicable to all other aspects and embodiments specified herein. Further, any of the features of one embodiment can be combined, in part or in whole, independently of the other embodiments described herein, for example, it may be possible to combine one, two, or three or more embodiments in whole or in part. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0101] These and other features, aspects, and advantages will be described below with reference to the drawings, which are intended to illustrate, but not limit, the invention. In the drawings, the same reference numerals consistently identify corresponding features throughout similar embodiments.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0103] Specific embodiments and examples are disclosed below, but 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. Accordingly, the scope set forth in 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 specific sequence disclosed. Various operations may be described one by one as a plurality of individual operations in a manner that may be helpful in understanding a particular embodiment, but the order of description should not be construed to mean that these operations are order-dependent. Additionally, the structures, systems, and / or devices described herein can be embodied as an integrated component or as separate components.

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

[0105] Introduction to the System U.S. Patent Application Publication No. US2013 / 0267811 (A1), the entire content of which is incorporated herein by reference, and FIG. 1 is a schematic diagram illustrating what a continuous analyte sensor system 100 attached to a recipient (e.g., a person) looks like. The analyte sensor system 100 communicates with other devices 110-113 (which can be positioned remotely from the recipient). A transdermal analyte sensor system 102 including a sensor assembly 600 on the skin is affixed to the recipient's skin via a base (not shown) that can be a disposable housing.

[0106] The system includes a transdermal analyte sensor 200 and an electronic device unit (alternatively referred to as a "sensor electronics" or "transmitter") 500 for wirelessly transmitting analyte information. The receiver can be positioned remotely from 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, smartwatches, tablet computers, laptop computers, and desktop computers. In some embodiments, the receiver can be an Apple Watch®, iPhone®, and iPad® manufactured by Apple. In further embodiments, the system 102 can be configured to be used when applying a drug delivery device such as an infusion device to a patient's skin. In such embodiments, the system can include a catheter instead of or in addition to the sensor, and the catheter is connected to an infusion pump configured to deliver a liquid drug or other fluid. In an embodiment, the catheter can be deployed into the skin in substantially the same manner as deploying the sensor as described herein.

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

[0108] In use, the sensing portion of the sensor 200 can be placed under the skin of the recipient, and the contact portion of the sensor 200 can be electrically connected to the electronic device unit 500. The electronic device unit 500 can be engaged with a housing attached to an adhesive patch fixed to the skin of the recipient.

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

[0110] The continuous analyte sensor system 100 can include a sensor configuration that provides an output signal indicative of the concentration of the analyte. The output signal (including sensor data such as, for example, raw data, filtered data, smoothed data, and / or otherwise transformed data, etc.) 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 entire content of which is incorporated herein by reference. In some embodiments, the sensor system 100 includes a continuous glucose sensor (as described, for example, 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), and the contents of U.S. Patent No. 6,565,509, U.S. Patent No. 6,579,690, and U.S. Patent No. 6,484,046, which provide transcutaneous sensors, are incorporated herein by reference in their entirety.

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

[0113] Various signal processing techniques and embodiments of glucose monitoring systems suitable for use with the embodiments described herein are described in U.S. Patent Application Publication No. US2005 / 0203360(A1) and U.S. Patent Application Publication No. US2009 / 0192745(A1), the contents of which are hereby incorporated by reference in their entirety. The sensor can extend through a housing that can maintain the sensor on the skin and can provide an electrical connection to a sensor electronics that can be provided within the electronic device unit 500.

[0114] In some embodiments, the sensor is formed from a wire or is in the form of a wire. The distal end of the wire can be sharpened to form a conical 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., a 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 but still flexible and strong. For example, in some embodiments, the minimum dimension of the elongated conductor is less than 0.1 inch, less than 0.075 inch, less than 0.05 inch, less than 0.025 inch, less than 0.01 inch, less than 0.004 inch, and / or less than 0.002 inch.

[0115] The sensor can have a circular cross-section. In some embodiments, the cross-section of the elongated conductor can be oval-shaped, rectangular, triangular, polygonal, star-shaped, C-shaped, T-shaped, X-shaped, Y-shaped, irregular-shaped, or the like. In some embodiments, a conductive wire electrode is used as the core. One or two additional conductive layers can be added to such an electrode (e.g., by an intervening insulating layer provided for electrical insulation). The conductive layer can 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 conductor (e.g., stainless steel, titanium, tantalum, platinum, platinum-iridium, iridium, certain polymers, and / or the like) can be made strong and hard and thus can withstand breakage. For example, in some embodiments, the maximum tensile strength of the elongated conductor is greater than 80 kPsi and less than 500 kPsi, and / or the Young's modulus of the elongated conductor is greater than 160 GPa and less than 220 GPa. The yield strength of the elongated conductor can be greater than 60 kPsi and less than 2200 kPsi.

[0117] The electronic device unit 500 can be releasably coupled to the sensor 200. The electronic device unit 500 can include electronic circuitry associated with the measurement and processing of continuous analyte sensor data. The electronic device unit 500 can be configured to perform algorithms associated with the processing and calibration of sensor data. For example, the electronic device 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 entire contents of each of which are incorporated herein by reference. The electronic device unit 500 can include hardware, firmware, and / or software that enables the measurement of analyte levels via a glucose sensor such as analyte sensor 200.

[0118] For example, the electronic device unit 500 can include a potentiostat, a power source for supplying power to 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 electronic device unit 500 and one or more receivers, repeaters, and / or display devices such as devices 110 - 113. The electronic device can be attached to a printed circuit board (PCB) or the like and can take various forms. For example, the electronic device can be in the form of an integrated circuit (IC) such as an application-specific integrated circuit (ASIC), a microcontroller, and / or a processor. The electronic device unit 500 can include a sensor electronic device configured to process sensor information such as data storage, analysis of data streams, calibration of analyte sensor data, estimation of analyte values, comparison of the estimated analyte value with the analyte value measured over time, analysis of variations in the estimated analyte value, and the like. Examples of systems and methods for processing sensor analyte data are described in more detail in U.S. Patent No. 7,310,544, U.S. Patent 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 / 0203360 (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 hereby incorporated by reference in their entirety into this specification.

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

[0120] Electronic device unit 500 can communicate with devices 110-113 and / or any number of additional devices via any suitable communication protocol. Exemplary communication protocols include wireless frequency, Bluetooth®, universal serial bus, IEEE 802.11, 802.15, 802.20, 802.22, and other 802 communication protocols, wireless local area network (WLAN) communication standards, including ZigBee, wireless (e.g., cellular) telecommunications, paging network communication, magnetic induction, satellite data communication, and / or proprietary communication protocols.

[0121] Additional sensor information is described in U.S. Patent No. 7,497,827 and U.S. Patent No. 8,828,201. The entire contents of U.S. Patent No. 7,497,827 and U.S. Patent No. 8,828,201 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. The sensor described in the context of any embodiment can be any sensor described or incorporated by reference herein. 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. The sensors 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, the ordinary and customary meaning of which is shown to those of ordinary skill in the art (and is not limited to a special or customized meaning), and further refers to substances or chemical components in a biological fluid that can be analyzed (e.g., blood, interstitial fluid, cerebrospinal fluid, lymph, urine, sweat, saliva, etc.), but is not limited thereto. Analytes can include naturally occurring substances, artificial substances, metabolites, 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 similarly contemplated, including ketone bodies, acetyl CoA, acarboxyprothrombin, acyl carnitine, adenine phosphoribosyltransferase, adenosine deaminase, albumin, alpha-fetoprotein, amino acid profile (arginine (Krebs cycle), histidine / urocanic acid, homocysteine, phenylalanine / tyrosine, tryptophan), androstenedione, antipyrine, arabinitol enantiomers, arginase, benzoylecgonine (cocaine), biotinidase, biopterin, c-reactive protein, carnitine, carnosinase, CD4, ceruloplasmin, chenodeoxycholic acid, chloroquine, cholesterol, cholinesterase, cortisol, testosterone, choline, creatine kinase, creatine kinase MM isozyme, cyclosporine A, d-penicillamine, de-ethylchloroquine, dehydroepiandrosterone sulfate, DNA (acetylation polymorphism, alcohol dehydrogenase, alpha1-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 hereditary optic neuropathy, MCAD, RNA, PKU, Plasmodium malariae, sex differentiation, 21-deoxycortisol), desbutylhalofantrine, dihydrofolate reductase, diphtheria / tetanus antitoxin, erythrocyte arginase, erythrocyte protoporphyrin, esterase D, fatty acid / acyl glycine, triglyceride, glycerol, free beta-human chorionic gonadotropin, free erythrocyte protoporphyrin, free thyroxine (FT4), free tri-iodothyronine (FT3), fumarylacetoacetase, galactose / gal-1-phosphate, galactose-1-phosphate uridyltransferase, gentamicin, analyte-6-phosphate dehydrogenase, glutathione, glutathione peroxidase, glycolic acid, 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, phenobarbital, phenytoin, phytanic acid / pristanic acid, progesterone, prolactin, prolidase, purine nucleoside phosphorylase, kinins, reverse tri-iodothyronine (rT3), selenium, serum pancreatic lipase, sisomicin, somatomedin C, specific antibodies (adenovirus, antinuclear antibody, anti-zeta antibody, arbovirus, OESK virus, dengue virus, guinea worm, tapeworm, dysentery amoeba, enterovirus, Giardia duodenalisa, Helicobacter pylori, hepatitis B virus, herpes virus, HIV-1, IgE (atopic diseases), influenza virus, Donovan Leishmania, leptospira, measles / mumps / rubella, mycoplasma pneumoniae, myoglobin, guinea worm, parainfluenza virus, Plasmodium falciparum, poliovirus, Pseudomonas aeruginosa, respiratory rash virus, rickettsia (scrub typhus), Schistosoma mansoni, Toxoplasma gondii, Treponoma pallidium, Trypanosoma cruzi / Langerhans, vesicular stomatis virus, Wuchereria bancrofti, yellow fever virus), specific antigens (hepatitis B virus, HIV-1), acetone (e.g., succinylacetone), acetoacetic acid, sulfadoxine, theophylline, thyrotropin (TSH), thyroxine (T4), thyroxine-binding globulin, trace elements, transferrin, UDP-galactose-4-epimerase, urea, uroporphyrinogen I synthase, vitamin A, white blood cells, and zinc protoporphyrin, but not limited to these.

[0125] Salts, sugars, proteins, lipids, vitamins, and hormones that are naturally present in blood or intestinal fluid can also constitute analytes in certain embodiments. Analytes can be naturally present in biological fluids or can be endogenous, such as metabolites, hormones, antigens, antibodies, etc. Alternatively, analytes can be introduced into the body or can be exogenous, such as contrast agents for imaging, radioisotopes, chemical agents, fluorocarbon-based synthetic blood, or drugs or pharmaceutical compositions, including insulin, glucagon, ethanol, cannabis (marijuana, tetrahydrocannabinol, hashish), inhalants (nitrous oxide, amyl nitrite, butyl nitrite, chlorinated hydrocarbons, hydrocarbons), cocaine (crack cocaine), stimulants (amphetamine, methamphetamine, Ritalin, Cylert, Preludin, Didrex, PreState, Voranil, Sandrex, Plegine), depressants (barbiturates, methaqualone, tranquilizers such as Valium, Librium, Miltown, Serax, Equanil, Tranxene, etc.), hallucinogens (fenciclonidine, lysergic acid, mescaline, peyote, psilocybin), narcotics (heroin, codeine, morphine, opium, meperidine, Percocet, Percodan, Tussionex, Fentanyl, Darvon, Talwin, Lomotil), designer drugs (analogs of fentanyl, meperidine, amphetamine, methamphetamine, and fenciclonidine, such as Ecstasy), anabolic steroids, and nicotine, among others. 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, norepinephrine, 3-methoxythyramine (3MT), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxytryptamine (5HT), and 5-hydroxyindoleacetic acid (FHIAA) can also be analyzed.

[0126] A number of embodiments described herein use an adhesive (e.g., adhesive 126 of FIG. 7). One purpose of the adhesive is to be able to couple the base, sensor module, and / or sensor to a 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 information about the adhesive pad is described in U.S. Patent Application No. 14 / 835,603, filed on August 25, 2015. The entire content of U.S. Patent Application No. 14 / 835,603 is incorporated herein by reference.

[0127] Location of the distal base As described above, the system can apply the on-skin sensor assembly to the recipient's skin. The system can include a base having an adhesive for coupling a 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 problem with this approach is that the insertion site (on the recipient's skin) is not ideally prepared for the insertion of the sensor and / or needle. For example, the distal end of the applicator can be a ring that presses against the skin. The pressure of the applicator against the skin can form a convex shape in the area of the skin within the ring. Additionally, the skin within the ring can be easily compressed too much, thus lacking sufficient elasticity and firmness of the skin. In this state, the sensor and / or needle may press the skin downward without immediately piercing the skin, resulting in an improper insertion of the sensor and / or needle.

[0129] In some embodiments, the base is coupled to the nested 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 nested assembly. This configuration allows the base to prepare for inserting the sensor and / or needle into the insertion site on the skin (e.g., by compressing the skin). Thus, these embodiments can dramatically improve the reliability of sensor and / or needle insertion while reducing the pain associated with sensor and / or needle insertion.

[0130] The system can hold the base at a position distal to the glucose sensor module such that the glucose sensor is not attached to the base and 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] Figure 2 illustrates a perspective view of an applicator system 104 for applying at least a portion of a sensor assembly 600 (shown in FIG. 4) on the skin to the skin of a recipient (e.g., a person). The system can include a sterile barrier having a shell 120 and a cap 122. The cap 122 can be screwed onto the shell 120 to protect a portion of the system 104 from external contaminants.

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

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

[0134] A number of different sterilization processes can be used with the embodiments described herein. The sterile barrier 120 and / or the 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 be configured to deform to create the seal. The threads 140 can be positioned between the sterile barrier shell 120 and the cap 122.

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

[0136] In some embodiments, at least one of the shell 120 and the cap 122 includes a gas-permeable material that allows a sterilizing gas to enter the applicator system 104. For example, as described in the context of FIG. 60, the system can include a cover 272h.

[0137] Referring to FIG. 3 below, the thread 140 can be configured to decouple the cap 122 from the shell 120 at 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 the thread 140. In some threaded embodiments, the cap 122 can be evenly pressed onto the shell 120 (e.g., during assembly).

[0138] The cap 122 can be fixed to the shell 120 by a frangible member 142 configured to brake the frangible member 142 when removing the cap 122 from the shell 120. The frangible member 142 can be configured like the safety ring (with a frangible part) of a plastic soda bottle. Loosening the cap from the plastic soda bottle separates the safety ring from the cap of the soda bottle. This approach provides evidence of tampering. Similarly, the applicator system 104 can provide evidence of tampering (by 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 on May 15, 2015, and U.S. Patent Application No. 62 / 244,520 filed on October 21, 2015, include 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] FIG. 3 illustrates a cross-sectional view of system 104. Glucose sensor module 134 is configured to couple sensor 138 to base 128 (e.g., a “housing”) for glucose. Nestable assembly 132 is positioned in a proximal starting position such that glucose sensor module 134 is positioned proximal and distal to base 128. Nestable assembly 132 is configured to connect glucose sensor module 134 to base 128 by compressing nestable assembly 132 via one or more mechanical interlocks (e.g., snap fit, interference features).

[0141] Sterile barrier shell 120 is coupled to nestable assembly 132. After removing cap 122, system 104 is configured to insert sensor 138 (shown in FIG. 4) into the recipient's skin by compressing sterile barrier shell 120 distally (while the distal portion of system 104 is pressed against the skin) to place transcutaneous glucose analyte sensor 138. In many of the drawings shown herein, sterile barrier shell 120 and cap 122 are hidden to make other features more clear.

[0142] Compressing nestable assembly 132 also pushes at least 2.5 millimeters of glucose sensor 138 through a hole in base 128 such that at least 2.5 millimeters of glucose sensor 138 that was previously positioned proximal to the distal end of the base projects distally from base 128. Thus, in some embodiments, base 128 can remain stationary relative to the distal portion of nestable assembly 132 while the compression movement of nestable assembly 132 moves glucose sensor module 134 toward base 128 and then couples sensor module 134 to base 128.

[0143] The relative movement between the sensor module 134 and the base 128 has a number of advantages, such as enabling the base to prepare for inserting the sensor and / or the needle into the skin insertion site (e.g., by compressing the skin). The starting position of the base 128 also enables the base 128 to protect people from the needles that may be positioned inside the applicator system 104. For example, if the base 128 is directly coupled to the sensor module 134 at the proximal starting position of the nested assembly, the needle can project distally from the base 128. The exposed needle can be potentially dangerous. In contrast, the distal starting position of the base 128 enables the base 128 to protect people from accidental needle insertion. Needle protection is particularly important for caregivers (not the recipients targeted by the skin sensor assembly 600 shown in FIG. 4).

[0144] FIG. 4 illustrates a perspective view of the skin sensor assembly 600 including the base 128. The adhesive 126 can couple the base 128 to the skin 130 of the recipient. The adhesive 126 can be a foam adhesive suitable for skin adhesion. The glucose sensor module 134 is configured to couple the 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., by coupling through mechanical interlocking such as snap fitting 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 skin 130 of the recipient.

[0146] After the glucose sensor module 134 is coupled to the base 128, the user (or applicator) can couple the electronic device unit 500 (e.g., a transmitter) to the base 128 via mechanical interlocking such as snap fitting and / or interference features. The electronic device unit 500 can measure and / or analyze the glucose metrics sensed by the glucose sensor 138. The electronic device 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] FIG. 5 illustrates a perspective view of the electronic device unit 500 coupled to the base 128 via mechanical interlocking such as snap fitting and / or interference features. The adhesive 126 on the 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 electronic device unit 500 coupled to the base 128.

[0148] Any of the features described in the context of FIGS. 1 - 6 can be applied to all aspects and embodiments specified herein. For example, a number of embodiments can use the on - skin sensor assembly 600 shown in FIG. 4 and can also use the sterile barrier shell 120 shown in FIG. 2. Further, any of the features of one embodiment can be combined, in part or in whole, independently of the other embodiments described herein. For example, it may be possible to combine one, two, or three or more embodiments, in whole or in part. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or device of another aspect or embodiment, and any aspect or embodiment of a system can 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 FIG. 3. In FIGS. 7-11, the sterile barrier shell 120 and the cap 134 are hidden to more easily examine the nested assembly 132.

[0150] The nested assembly 132 is part of a system for applying the skin-mounted sensor assembly 600 to the skin of a recipient (shown in FIG. 4). The nested assembly 132 can apply a portion of the system to the recipient. An additional portion of the system can be added to the skin-mounted sensor assembly 600 after the applicator system 104 has coupled an initial portion of the sensor assembly 600 to the recipient. For example, as shown in FIG. 4, the electronic device unit 500 (e.g., a transmitter) can be coupled to the skin-mounted sensor assembly 600 after the applicator system 104 (shown in FIG. 3) has coupled the base 128, the glucose sensor module 134, and / or the glucose sensor 138 to the skin 130 of the recipient.

[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, namely, the electronic device unit 500, the glucose sensor module 134, the glucose sensor 138, the base 128, and the adhesive 126, to the skin of the recipient. The electronic device unit 500 can be positioned inside the applicator system 104 such that the applicator system 104 is configured to couple the electronic device 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”) from a proximal starting position to a distal position along path 154. FIG. 7 illustrates the nested assembly 132 in the proximal starting position. FIG. 8 illustrates the nested assembly 132 moving between the proximal starting position and the distal position. FIG. 11 illustrates the nested assembly 132 in the distal position. Path 154 (shown in FIG. 7) represents the travel between the proximal starting position and the distal position.

[0153] A first set of items can be stationary relative to the first portion 150, and a second set of items can be stationary relative to the second portion 152 while the first set of items is moving relative to the second set of items.

[0154] Referring now to FIG. 7, the glucose sensor 138 and the sensor module 134 are coupled to the first portion 150 (e.g., such that they are stationary relative to the first portion 150, e.g., between the proximal portions of path 154). The base 128 is coupled to the second portion 152 such that the base 128 projects from the distal end of the system (e.g., the base projects 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 firmly coupled to the base 128).

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

[0156] The sensor module 138 is coupled to the distal portion of the first portion 150 such that (as described above) moving the first portion 150 to the distal position couples the sensor module 134 to the base 128. The glucose sensor 138 is coupled to (e.g., stationary with respect to) the sensor module 134 while the first portion 150 is positioned at the proximal starting 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, even if the distal protruding portion can be bent with respect to the sensor module 134, the proximal portion cannot move with respect to the sensor module 134.

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

[0158] The needle 156 has a number of different forms. A number of different types of needles 156 can be used with the embodiments described herein. FIGS. 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 recipient's skin. The distal portion of the sensor 138 can be positioned within the channel of the needle 156 (as shown in FIG. 42). At times, the distal end of the sensor 138 protrudes from the needle 156 as the sensor 138 and the needle 156 are inserted into the recipient and catches on the recipient's tissue. As a result, the sensor 138 can become distorted and not be inserted deeply enough into the subcutaneous tissue. In other words, in some embodiments, the sensor wire must be disposed within the channel of the C-shaped needle 156 that is being guided into the tissue and must be held within the channel 330 during deployment.

[0160] The risk that sensor 138 protrudes from channel 330 (and thus cannot be properly inserted into the recipient) can be significantly reduced by the embodiment illustrated in FIG. 51. In this embodiment, adhesive 376 adheres the distal portion of glucose sensor 138 to channel 330 of needle 156. Storing needle 156 can break the adhesion of adhesive 376 and allow the distal portion of sensor 138 to remain in a subcutaneous location while (and even after) needle 156 is stored.

[0161] The risk that sensor 138 protrudes from channel 330 (and thus cannot be properly inserted into the recipient) can be significantly reduced by the embodiments illustrated in FIGS. 52 and 53. In this embodiment, needle 156a comprises two side portions that can be separated by slot 378. Sensor 138 can have a width greater than the width of slot 378 so that sensor 138 cannot emerge from channel 330a until the two side portions of needle 156a move apart (so as to widen slot 378).

[0162] The embodiment illustrated in FIG. 54 can be used in conjunction with any of the other embodiments described herein. Needle 156b includes a ramp portion 380 at the distal end of channel 330b. The distal end of needle 156b can include a conical tip 382. Ramp portion 380 can be configured to push sensor 138 out of channel 330b of needle 156b as needle 156b is stored in nested assembly 132 (shown in FIG. 7).

[0163] FIG. 55 illustrates cross-sectional views 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, a number of other C-shaped needles can be used. The ends of needle 156d can be angled with respect to each other. In some embodiments, the ends of the needle can be angled away from each other in an opposing manner as shown by 156d. In some embodiments, the ends of the needle can have a spreading edge, and the spreading edge is rounded to prevent the sensor from contacting the sharp edge. The ends of needle 156e can be parallel and / or flat with respect to each other. The outer portion of channel 330f can be formed by walls that are linear and / or parallel to each other (rather than by a curved wall as in the case of the other needles 156d, 156e). Some needles 156d can be manufactured via laser cutting, some needles 156e can be manufactured via wire electrical discharge machining ("EDM"), and some needles 156f can be manufactured via punching.

[0164] As shown in FIG. 7, needle hub 162 is coupled to needle 156. The needle hub includes a release feature 160 that projects outward. In some embodiments, the release feature can include one, two, or more flexible arms. The outer edge 164 of the release feature 160 catches on an overhang 166 (e.g., an undercut, a detent) that faces inward of the first portion 150 so as to move the first portion 150 distally with respect to the second portion 152 to move the needle storage mechanism 158 to the release point distally.

[0165] At the release point, the proximal projection 170 of the second portion 152 engages the release feature 160 (shown in FIG. 9), which bends the release mechanism 160 inwardly (shown in FIG. 10) until the release feature 160 is no longer snagged on the overhang 166 of the first portion 150. When the release feature 160 is no longer snagged on the overhang 166 of the first portion 150, the spring 234 of the needle storage mechanism 158 pushes the needle 156 and the needle hub 162 proximally with respect to the first portion 150 and with respect to the second portion 152 until the needle no longer protrudes distally from the base 128 and is completely hidden inside the nested assembly 132 (shown in FIG. 11).

[0166] The needle 156 can be removed from the embodiment illustrated in FIG. 7 to create a needleless embodiment. Thus, the needle 156 is not used in some embodiments. For example, the distal end of the glucose sensor 138 can be formed in a conical shape to allow insertion of the glucose sensor 138 into the skin without using 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 assist in guiding 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 assist in guiding the glucose sensor 138 into the skin. Skin penetration is an important consideration in both needle and needleless embodiments. Failure to properly penetrate the skin can lead to improper placement of the glucose sensor 138.

[0168] Applying tension to the skin before piercing the skin with the glucose sensor 138 and / or the needle 156 can dramatically improve the stability of achieving proper placement of the glucose sensor 138. Tension can be applied to the skin by compressing the skin with a distal projecting shape (e.g., a convex shape) before and at the moment of piercing the skin with the glucose sensor 138 and / or the needle 156.

[0169] FIG. 12A illustrates a portion of the cross-section shown in FIG. 7. The base 128 includes an optional distally facing protrusion 174 positioned distally with respect to the second portion 152 (and with respect to the remaining nested assembly 132). The distal protrusion 174 is convex and is formed in a dome shape. 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] The distal protrusion 174 can be positioned more distally than any other portion of the base 128. The distal protrusion 174 can extend through the hole 176 into the adhesive 126 (also shown in FIG. 5). The distal portion of the convex protrusion 174 can be positioned distally with respect to the adhesive 126, while the proximal portion of the convex protrusion 174 can be positioned proximally with respect to the adhesive 126.

[0171] The distal protrusion 174 has a hole 180 through which the needle 156 and / or the glucose sensor 138 can pass. The distal protrusion 174 can compress the skin such that the distal protrusion 174 is configured to reduce the skin's resistance to piercing.

[0172] FIG. 12B illustrates a cross-sectional view of a base 128b that is the same as the base 128 shown in FIGS. 7 and 12B, except for the following features. The base 128b does not include the protrusion 174. The base 128b includes a funnel 186 (e.g., a rounding) on the distal side of the hole 180b.

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

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

[0175] Needle 156 having slot 184 passes through aperture 180 of the distal projection and aperture 176 of adhesive 126. A portion of glucose sensor 138 is positioned within slot 184 such that the portion of the glucose sensor 138 moves distally relative to base 128 (shown in FIG. 12A) without the needle 156 displacing the portion of the glucose sensor 138 out of slot 184. Distal projection 174 is convex such that distal projection 174 applies tension to the skin while the first portion 150 of nested assembly 132 (shown in FIG. 7) moves distally relative to the second portion 152 to prepare to pierce the skin.

[0176] As described 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 outer periphery of the projection 174 such that the outer periphery of the hole 176 is positioned radially outward of the outer periphery of the projection 174 that connects the distal projection 174 to the remaining base 128.

[0177] In some embodiments, the hole 176 of the adhesive 126 is large enough such that the adhesive 126 does not cover any of the distal projections 174. In some embodiments, the adhesive 126 covers at least a portion, and even a majority, of the distal projection 174. Thus, the adhesive 126 need not be planar and can be raised distally in the region over the distal projection 174.

[0178] In some embodiments, the adhesive 126 has a non-uniform thickness such that the thickness of the adhesive 126 is greater in the region surrounding the needle exit region than in other regions further radially outward from the needle exit region. Thus, the distal projection 174 can be part of the adhesive 126 rather than part of the base 128. However, in some embodiments, the base 128 can include the adhesive 126 and the distal projection 174 can 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 the angled portion of the tip of the needle. The purpose of the angled portion is to form a sharpened end to facilitate tissue penetration. The sensor 138 has a distal end 208.

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

[0181] Referring now to FIG. 12A, the distal protrusion 174 can project at least 0.5 millimeter and less than 5 millimeters from the distal face of the adhesive 126. In embodiments where the adhesive 126 has a non-planar distal surface, the distal protrusion 174 can project at least 0.5 millimeter and less than 5 millimeters from the average distal location of the adhesive 126.

[0182] As described above, in some embodiments, the base is coupled to the nested assembly such that the glucose sensor is positioned remotely from the base and while the base projects from the distal end of the system while the nested assembly is positioned within. However, in other embodiments, the base is coupled to the nested assembly such that as a first portion of the base moves distally relative to a second portion of the nested assembly, the base is fully positioned within the nested assembly and the base 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 at the proximal starting 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 the distal end portion of the first portion 150 while the first portion 150 is positioned at the proximal starting position. All of the features and embodiments described herein can be configured and used with the positioning of the base 128 as described in the context of FIG. 59.

[0184] All of the embodiments described herein can be used with a base coupled to a nested assembly such that as the first portion moves distally relative to the second portion of the nested assembly, the base is fully positioned within the nested assembly and the base moves distally with the sensor. All of the embodiments described herein can be used with a base coupled to a nested 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 nested assembly.

[0185] Sensor Module Docking and Base Removal As described above, maintaining the base against the skin during sensor and / or needle insertion enables significant medical advantages. However, maintaining the base against the skin may require moving the sensor relative to the base during the insertion process. At the time of insertion, it is necessary to couple the sensor to the base to prevent the sensor from being inadvertently dislodged from the base. Accordingly, there is a need for a system that allows the sensor to be moved relative to the base (without undue burden on the user) and further allows the sensor to be latched to the base.

[0186] During distal movement of the sensor and / or the needle, maintaining the base with respect to the skin is made possible in a number of embodiments by a unique coupling system that fixes the sensor (and sensor module) to a first part of the nested assembly and fixes the base to a second part of the nested assembly. Moving the first part towards the second part 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 remove the base and sensor from the nested assembly (which can be disposable or reusable with different sensors).

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

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

[0189] After “docking” the sensor module 134 and the glucose sensor 138 to the base 128, the system can remove the base 128 from the nested assembly 132 and bond the sensor module 134, the glucose sensor 138, and the base 128 to the skin by an adhesive 126, while enabling the nested assembly 132 and other parts of the system to be discarded.

[0190] As shown in FIG. 7, the sensor module 134 is coupled to the first portion 150 while the first portion 150 is in the proximal starting position and is positioned at least 5 millimeters from the base 128. The system is configured to move the first portion 150 (as shown in FIG. 11) towards the distal position to couple 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 starting 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 FIG. 7. Arrow 190 illustrates the distal direction in FIG. 7. Line 172 illustrates the horizontal direction. As used herein, horizontal means within ±20 degrees of perpendicular to the central axis 196.

[0192] FIG. 15 illustrates a perspective view of a cross-section of a portion of the system shown in FIG. 7. The cross-section is cut through the hole 180 of the base 128. The visible parts include the sensor module 134, the sensor 138, the seal 192, the needle 156, the base 128, and the adhesive 126. The sensor module 134 is in the proximal starting position. The seal 192 is configured to prevent fluid (e.g., body fluid) from entering the glucose sensor module 134.

[0193] The glucose sensor 138 is mechanically coupled to the sensor module 134. The glucose sensor 138 extends into the inner portion of the sensor module 134 and is electrically coupled to the interconnect at the inner portion of the sensor module 134. In FIG. 15, the interconnect is hidden to more readily visualize the proximal portion of the glucose sensor 138 within the inner portion of the sensor module 134. Also in FIG. 15, many other parts of the system are hidden to enable a clear observation of the visible portions.

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

[0195] Referring now to FIGS. 7 and 15, the sensor module 134 is stationary relative to the first portion 150 during the first portion of 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 path 154, move the sensor module 134 toward the base 128, move a portion of the sensor 138 through the aperture 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] FIG. 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 the central axis 196 is hidden to avoid obscuring the arrow representing path 154 and to avoid obscuring the needle 156.)

[0197] FIG. 15 illustrates the flex arm 202 of the sensor module 134. The flex arm 202 is horizontally oriented and configured to secure the sensor module 134 to the protrusion of the base 128. In some embodiments, the flex arm 202 is an alignment arm for preventing and / or hindering rotation of the sensor module 134 relative to the base 128.

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

[0199] Referring now to FIGS. 15 and 16, the flex arm 202 extends from the outer periphery of the sensor module 134. The base 128 includes a protrusion 206 that extends from a horizontal portion of the plane of the base 128.

[0200] Referring now to FIG. 16, each of the proximal protrusions 206 of the base 128 is coupled to the flex arm 202 of the sensor module 134. Thus, the coupling of the proximal protrusion 206 to the flex arm 202 secures 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 the central axis of each proximal protrusion 206. In some embodiments, the locking protrusion 212 extends horizontally (as shown, for example, in FIG. 15). Each horizontal locking protrusion 212 is coupled to the end portion 210 of the flexible arm 202.

[0202] The end portions 210 of each flexible arm 202 can extend at an angle greater than 45 degrees and less than 135 degrees with respect to the central axis of the majority of the flexible arm 202. The end portions 210 of each flexible arm 202 can include horizontal locking protrusions (as shown, for example, in FIG. 15).

[0203] In FIGS. 15 and 16, a first horizontal locking protrusion is coupled to the end portion 210 of the first flexible arm 202. A 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 under 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 nested assembly 132 to the distal position (shown in FIG. 11) bends the first flex arm 202 such that the first horizontal locking protrusion of the flex arm 202 moves 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., the 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 nested assembly 132 to the distal position bends the flex arm 202 (e.g., the end portion 210) away from the remaining sensor module 134 (e.g., outwardly) such that the horizontal locking protrusion of the flex arm 202 can 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 plurality of flexible arms 202, and the base can have a plurality of proximal protrusions 206 configured to couple the sensor module 134 to the base 128. In some embodiments, the first flexible arm 202 is positioned on the opposite side of the sensor module 134 relative to the second flexible arm 202 (as shown, for example, in FIGS. 15 and 16).

[0206] In some embodiments, the base 128 includes a flexible arm (such as the flexible arms 202 shown, for example, in FIGS. 15 and 16), and the sensor module 134 includes a protrusion for coupling to the flexible arm of the base 128. The protrusion of the sensor module 134 can be similar to the protrusion 206 shown in FIGS. 15 and 16, except that in some embodiments the protrusion extends distally toward the flexible arm of the base 128. Thus, the base 128 can be coupled to the sensor module 134 by the flexible arm and the engaging protrusion, regardless of whether the base 128 or the sensor module 134 includes a flexible arm.

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

[0208] Docking the sensor module 134 to the base 128 can 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 toward the base 128. Securing the sensor module 134 to the first portion 150 of the nested assembly 132 requires high reliability, but the sensor module 134 is temporary such that it can be removed from the first portion 150 at an appropriate stage. The structure for securing the sensor module 134 to the first portion 150 of the nested assembly 132 generally needs to avoid interfering with the docking process.

[0209] FIG. 17 illustrates a cross-sectional view of a first portion 150 of the nested 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, many items are 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, and while the first position 150 is in the proximal starting position (shown in FIG. 7), the arms project distally and latch engage over the sensor module 134 to removably secure the sensor module 134 to the first position 150. The flex arms 214, 216 can be coupled to the outer periphery of the sensor module 134 such that the distal ends of the flex arms 214, 216 wrap around the distal surface of the sensor module 134. In some embodiments, the distal ends of the flex arms 214, 216 are positioned distally of the sensor module 134 while the first portion 150 is in the proximal starting position.

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

[0212] Referring to FIGS. 7 and 17 below, the sensor module 134 is configured to couple the sensor module 134 to the base 128 as the system moves the first portion 150 distally relative to the second portion 152, while the base 128 protrudes from the distal end of the system. The sensor module 134 is positioned within the second portion 152 while the base 128 protrudes from the distal end of the system, even if 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 the internal region of the second portion 152 of the nested assembly 132 without moving the base 128 through the internal 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. The first flexure arm 214 and the second flexure arm 216 of the first portion 150 secure the sensor module 134 to the first portion 150 such that the sensor module 134 is releasably engaged with the first portion 150 with a first vertical holding strength (measured along the vertical central axis 196).

[0214] As shown in FIGS. 15 and 16, the sensor module 134 is coupled to the base 128 via at least one flexure arm 202 such that the sensor module 134 is coupled to the base 128 with a second vertical holding strength. The flexure arm 202 can extend from the outer periphery of the sensor module 134. The flexure arm 202 can be part of the base 128.

[0215] Referring to FIG. 17 below, in some embodiments, the second vertical holding strength is greater than the first vertical holding strength such that continuing to push the first portion 150 distally when the sensor module 134 is coupled to the base 128 overcomes the first and second flexure 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 holding strength is at least 50 percent greater than the first vertical holding strength. In some embodiments, the second vertical holding strength is at least 100 percent greater than the first vertical holding strength. In some embodiments, the second vertical holding strength is less than 400 percent greater than the first vertical holding strength.

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

[0218] As described above, maintaining the base against the skin during insertion of the sensor and / or needle enables significant medical advantages. 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 the base has moved distally downward with the needle. This relatively long stroke can enable some base removal mechanisms. In contrast, when maintaining the base in a fixed position as the needle moves toward the base, releasing the base can involve problems.

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

[0220] As shown in FIGS. 7-11, in some embodiments, as the sensor module 134 moves toward the base 128, the base 128 is held in a fixed position relative to the second portion 152 of the nested assembly 132. Referring now to FIG. 18, when 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 in a state prior to the sensor module 134 docking with the base 128, in order to illustrate the distal protrusion 222 of the first portion 150 that is aligned with the flex arm 220 such that (via the distal protrusion 222 contacting the flex arm 220) the distal protrusion 222 is configured to bend the flex arm 220.

[0221] The distal protrusion 222, as shown in FIGS. 11 and 16, after the sensor module 134 is coupled to the base 128, bends the flex arm 220 to remove the base 128 from the nested assembly 132 (shown in FIG. 7). The flex arm 220 can include a ramp portion 224. The distal end of the distal protrusion 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 achieved by moving the first portion 150 distally relative to the second portion 152, which moves the distal protrusion 222 as shown by arrow 226.

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

[0223] In contrast, when the holding force and the unlocking force are oriented along the same axis (e.g., within ±20 degrees), the holding force is typically less than or equal to the unlocking force. However, the unique structure shown in FIG. 18 enables the holding force to be at least twice as large (and in some cases at least four times as large) as the unlocking force. As a result, the system can prevent accidental unlocking of the base 128 while having an unlocking force 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 to control the sequence of locking and unlocking operations. In other words, the structure is such that premature locking and unlocking do not occur. In a medical situation, where reliability is of utmost importance, this control is extremely beneficial. For example, in some embodiments, the process follows the following sequence. The sensor module 134 is coupled to the base 128. Then, the first portion 150 releases the sensor module 134. Then, the second portion 152 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 can move from the proximal starting position to the distal position along the path previously described. (Some embodiments use different sequences of locking and unlocking operations.)

[0225] FIG. 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 at the proximal starting position. At least a majority of the sensor module 134 and the glucose sensor 138 are positioned remotely from the base 128. The system is configured to couple the sensor module 134 and the glucose sensor 138 to the base 128 by moving the first portion 150 distally relative to the second portion 152.

[0226] Referring now to FIGS. 18 and 19, the base 128 includes a first radially protruding portion 230 (e.g., a locking feature) releasably coupled to a second radially protruding portion 232 (e.g., a locking feature) of the second portion 152 of the nested assembly 132 (shown in FIG. 7) with a first vertical holding force. The first radially protruding portion 230 protrudes inwardly and the second radially protruding portion 232 protrudes outwardly. The system is configured to move the first portion 150 to a distal position to move the second radially protruding portion 232 relative to the first radially protruding portion 230 to remove the base 128 from the nested assembly 132.

[0227] The first portion 150 of the nested assembly 132 includes a first arm 222 protruding distally. The second portion 152 of the nested assembly 132 includes a second flex arm 220 protruding distally. The first arm 222 and the second flex arm 220 can be oriented within 25 degrees of each other (when measured between their central axes). The system is configured to move the first portion 150 along path 154 (shown in FIG. 7) from the proximal starting position to the distal position to deflect the second flex arm 220 against the first arm 222, thereby enabling the second flex arm 220 to remove the base 128 and decouple the base 128 from the nested 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 the proximal starting position, the first arm 222 of the first portion 150 is aligned at least partially perpendicular to the second flex arm 220 of the second portion 152, allowing the first arm 222 to deflect the second flex arm 220 as the first portion moves to the 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., the lamp portion 224) of the second arm 220. This protrusion can be configured such that a collision between the first arm 222 and the protrusion enables the second arm 220 to be deflected (to remove the base 128 from the second portion 152).

[0230] In the embodiment illustrated in FIG. 18, when the first portion 150 is in the proximal starting position, at least a section of the first arm 222 is positioned directly over at least a portion of the second flex arm 220, allowing the first arm 222 to deflect the second flex arm 220 as the first portion 150 moves to the distal position described above. The second flex arm 220 includes a first horizontal protrusion (e.g., the locking feature 232). The base 128 includes a second horizontal protrusion (e.g., the locking feature 230) that is latch - engaged with the first horizontal protrusion to couple the base 128 to the second portion 152 of the nested 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 to unlatch the base 128 from the nested assembly 132.

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

[0232] The third flexure arm (e.g., flexure arm 202 of FIG. 15) attaches the glucose sensor 138 to the base 128 at a first position. The second flexure arm (e.g., flexure arm 220 of FIG. 18) is removed from the base at 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 after the glucose sensor 138 is fixed to the base 128.

[0233] Compression of the spring The needles used in a glucose sensor inserter can be dangerous. For example, accidental needlesticks can transmit disease. Using a spring to store the needle can reduce the risk of injury by the needle.

[0234] Referring now to FIG. 7, a spring 234 (e.g., a coil spring) can be used to store a needle hub 162 that supports a C-shaped needle 156. The needle hub 162 can be released at the bottom of the insertion depth (to enable storing the needle 156). For example, when the needle 156 reaches its maximum distal position, the latch 236 can be released to allow the spring 234 to proximally push the needle 156 into the protective housing (e.g., into a first portion 150 that can serve as the 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 a non-compressed spring is that the first and second portions of the nested assembly can move slightly freely relative to each other (when the assembly is in the proximal starting position). This "chattering" of the first and second portions can make the assembly appear weak and brittle.

[0236] Many of the components described in this specification can be molded from plastic (although springs are often metal). Preventing creep in plastic components can help ensure that the applicator functions the same when it is manufactured and after long periods. One way to reduce the risk of creep is to not place the part under a large enough (e.g., during storage) load that would deform the plastic during storage.

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

[0238] Transdermal and implantable sensors are affected by in vivo properties and physiological responses in the surrounding tissue. For example, a decrease in sensor accuracy after implantation of the sensor is a commonly observed phenomenon. This phenomenon is sometimes referred to as the "drop-off recovery" process. Drop-off recovery is triggered by trauma due to the insertion of the implantable sensor and perhaps by the stimulation of nerve bundles near the implantation area, which results in the nerve bundles reducing blood flow to the implantation area.

[0239] Alternatively, drop-off recovery is associated with damage to adjacent blood vessels, which can result in a vasospasm event. Any local cessation of blood flow in the implantation area over 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 a reduced sensitivity and cannot accurately track glucose. Thus, drop-off recovery appears as a suppressed glucose signal. The suppression signal from drop-off recovery often appears in the signal within one day after implantation and most commonly within the first 12 hours after implantation. Drop-off recovery usually resolves within 6 - 8 hours.

[0240] The identification of a drop and recovery can provide information to the patient, physician, or other user that the sensor is only temporarily affected by short-term physiological responses and that there is no need to remove the implant since it can return to normal function 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 a drop and recovery. Quick needle retraction aids in limiting the time the needle is in the body. A large spring retraction force enables the needle to be retracted quickly.

[0242] The embodiment illustrated in FIG. 7 solves the problem of "chattering", avoids significant creep, and enables quick needle retraction. The embodiment places a slightly preloaded spring 234 between a first portion 150 and a second portion 152 of the nested assembly 132. In other words, when the first portion 150 is in the proximal starting position, the spring 234 is in a slightly compressed state since 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] Spring 234 is further compressed when the first portion 150 moves distally relative to the second portion 152. In some embodiments, this slight preload has a compression length that is much shorter than the compression length of a typical fully pre-compressed spring. In some embodiments, the preload results in a compression length of spring 234 that is less than 25 percent of the compression length of the fully compressed spring 234. In some embodiments, the preload results in a compression length of spring 234 that exceeds 3 percent of the compression length of the fully compressed spring 234. The slight preload eliminates “chattering” while having too little force to cause significant creep of non-spring components within the system.

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

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

[0247] Spring 234 is further compressed during activation of the applicator and during nesting (e.g., while pushing and 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 pushed radially inward by a feature (e.g., protrusion 170) within the nested assembly 132 (as shown by the progression of FIGS. 7-11). This releases the needle hub 162 and allows spring 234 to extend and drive the needle 156 proximally into the recipient (and into the first portion 150 and / or the second portion 152).

[0248] As shown in FIG. 7, the base 128 projects from the distal end of the system while the first portion 150 of the nested assembly 132 is positioned in the proximal starting position and the glucose sensor 138 is positioned remotely from the base 128. Since 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, the glucose sensor 138 is movably coupled to the base 128 via the nested assembly 132.

[0249] The system includes a spring 234 configured to store the needle 156. The needle 156 is configured to facilitate insertion of 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 starting 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 starting position increases the compression of the spring 234. The first compressed state positions 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 the tensioned state. In other words, at the proximal starting position, the latch engagement feature is configured to prevent the spring 234 from pushing the first portion 150 proximally against 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 store the needle 156. This low potential energy of the partially pre-compressed spring 234 is typically insufficient to cause creep and is further typically sufficient to eliminate the "chattering" described above.

[0252] The redundant system can assist in ensuring that the needles 156 (and in some cases, the sensors 138) can be routinely removed from the recipient after they have been inserted into the recipient. In extreme cases, where the required needle removal force is greater than the spring storage force, the user can pull the entire nested assembly 132 proximally to remove the needles 156 and / or sensors 138 from the recipient.

[0253] Some embodiments include a secondary storage spring. In other words, in some embodiments, the spring 234 of FIG. 7 is actually two concentric springs. (In some embodiments, the 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 storage force and can allow for additional adjustment of the force profile.

[0254] Many users desire to minimize the amount of material that they discard (as waste). Moving the needle 156 rearward of the applicator after deployment allows for easy access to remove the needle 156 after deployment.

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

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

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

[0258] Removing the cover 272 can enable the user to remove the needle 156 from the applicator (e.g., the nested assembly 132) such that the user can insert the needle 156 into a sharps waste container and reuse the applicator with a new needle. Removing the needle 156 from the applicator can also enable reducing the amount of waste that needs to be held by the sharps waste container by putting the remaining applicator into a general waste collector.

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

[0260] FIG. 60 illustrates a perspective view of another nested assembly embodiment 132h. A cover 272h is adhered to the proximal end of the nested assembly 132h to cover a hole 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 nested assembly 132h can enable the user to discard the needle 156 (shown in FIG. 7) into a sharps waste container.

[0261] In this embodiment, the cover 272h is a flexible film such as a Tyvek label made by E.I. du Pont de Nemours and Company (“DuPont”). The cover 272h can include an adhesive for adhering the cover 272h to the proximal end of the nested assembly 132h.

[0262] In some embodiments, the second cover 272 is adhered to the distal end of the nested assembly 132h to cover 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 enable a sterilization process to facilitate sterilization inside the nested assembly 132h by allowing the sterilization gas to pass through the material of the cover 272h. For example, the cover 272h can be passed through with a sterilization gas.

[0264] Any of the features described in the context of FIG. 60 can be applied to all aspects and embodiments specified herein. For example, the embodiments described in the context of FIG. 60 can be combined with the embodiments described in the context of FIGS. 1-59 and FIGS. 61-70.

[0265] The nested assembly 132h can use the same internal features and components as those described in the context of FIG. 7. One important difference is that the first part 150h slides on the outer surface of the second part 152 (rather than sliding inside the second part 152 as shown in FIG. 7). Also, the nested assembly 132h does not use a sterile barrier shell 120 (as shown in FIG. 2).

[0266] Any of the features described in the context of FIGS. 7-22 can be applied to all aspects and embodiments specified in this specification. For example, the embodiments described in the context of FIGS. 7-22 can be combined with the embodiments described in the context of FIGS. 23-70. Further, any of the features of one embodiment can be combined, in part or in whole, independently of the other embodiments described in this specification. For example, it may be possible to combine one, two, or three or more embodiments, in whole or in part. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0267] Force profile Referring now to FIG. 7, in some embodiments, moving the first portion 150 of the nested assembly 132 distally relative to the second portion 152 typically involves positioning the distal end of the system against the recipient's skin and then applying a distal force to the proximal end of the system. This distal force moves the first portion 150 distally relative to the second portion 152 to deploy the needle 156 and / or the 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 in a particular part of the distal actuation can be much less than ideal in another part of the distal actuation.

[0269] The user positions an applicator (e.g., the nested assembly 132) against the skin surface and applies a distal force to the applicator (e.g., by depressing the proximal end of the applicator). When the force generated by the user exceeds a threshold, the applicator is compressed (e.g., nested distally), and the user drives the sensor into the body.

[0270] Some embodiments include a unique force profile that reduces accidental premature deployment, dramatically increases the likelihood of complete and proper deployment, and also reduces patient discomfort. Certain structures enable these unique force profiles. For example, the following structures, namely, a structure for holding the nested assembly 132 in the proximal starting position, a structure for attaching the sensor module 134 to the base 128, a structure for releasing the sensor module 134 from the first portion 150, a structure for preventing premature storage of the needle 156, a structure for storing the needle 156, a structure for releasing the base 128 from the second portion 152, a structure for absorbing collisions at the distal position, and a structure for holding the nested assembly 132 in the distal end position can enable the unique force profiles described herein. These structures are described in various sections of this specification.

[0271] Some embodiments include a system for applying the on-skin sensor assembly 600 to the skin 130 (shown in FIG. 4) of a recipient. Referring now to FIG. 7, the system can include a nested assembly 132 having a first portion 150 configured to move distally relative to a second portion 152 from a proximal starting position to a distal position along a path 154, 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] The first portion 150 is releasably fixed in the proximal starting position by a fixing mechanism (e.g., the combination of 240 and 242 in FIG. 7) that prevents the first portion 150 from moving distally relative to the second portion 152. The system is configured to release the latch 236 to move the first portion 150 distally relative to the second portion 152 before and / or upon reaching the distal position, thereby causing the needle 156 to be stored proximally into the system.

[0273] In some embodiments, the fixation mechanism is formed by an interference portion between a first portion 150 and a second portion 152. The interference portion can be configured to prevent the first portion 150 from moving distally relative to the second portion 152. For example, a radially outward protrusion 240 of the first portion 150 must overcome a force threshold to move the first portion 150 distally, deforming the first portion 150 and / or the second portion 152 such that the radially outward protrusion 240 can move distally relative to the proximal end 242 of the second portion 152 by colliding with the proximal end 242 of the second portion 152.

[0274] The system can include a first force profile measured along a path 154. As shown in FIG. 23, the force profile 244 can include force on the Y-axis and travel distance on the X-axis. Referring below to FIGS. 7 and 23, the force profile 244 can be measured along the central axis 196.

[0275] One way to measure the force profile 244 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 drive the nested assembly 132 along the path 154 from a proximal starting position to a distal position by pressing on the proximal side of the force gauge. FIG. 23 illustrates the relationship between force and distance from the proximal starting position based on this type of test procedure.

[0276] The first force profile 244 can include a first magnitude 246 corresponding to overcoming the fixation mechanism (e.g., 240 and 242), a third magnitude 250 corresponding to releasing the latch 236 (e.g., releasing the needle storage mechanism), and a second magnitude 248 corresponding to an intermediate portion of the path 154 that is distal to overcoming the fixation 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 of 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 acceleration of the needle during an intermediate portion of path 154 to allow for an appropriate needle velocity when the needle 156 (or glucose sensor 138) first penetrates the skin.

[0280] The first magnitude 246 can be the peak force required to overcome the securing mechanisms (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 immediately before the needle 156 begins to retract proximally. The slope of the force profile 244 can be positive over at least 1 millimeter during the time the second magnitude 248 is measured (by the spring force increasing as the spring compression increases).

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

[0282] To provide a sufficient safety margin, the first magnitude 246 can be made at least 50 percent larger than the third magnitude 250. In some embodiments, the first magnitude 246 can be made at least 75 percent larger than the third magnitude 250. To avoid the first magnitude 246 becoming higher than necessary in view of the force required for the system along path 154 with respect to the first magnitude 246, the first magnitude 246 can be made less than 250 percent larger than the third magnitude 250.

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

[0284] In response to compressing the spring 234 configured to enable the system to store the needle 156 into the nested assembly 132, the proximal millimeter of the second force profile 252 has an average force that is lower than the average force of the distal millimeter of the 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 that corresponds to moving distally past the proximal half of the fixation mechanism, and a second average magnitude that corresponds 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 sensor insertion cycle from starting unless the user applies sufficient force to complete the sensor insertion cycle.

[0286] A first force peak 256 corresponds to 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 that corresponds to overcoming the fixation mechanism and a subsequent magnitude that corresponds to stopping the fixation mechanism (e.g., moving past the distal portion of the fixation mechanism). The first magnitude 246 comprises a proximal vector and the subsequent magnitude comprises a distal vector. Since FIG. 23 is truncated at zero force, the distal vector appears to have a magnitude of zero in FIG. 23, but the actual value is negative (e.g., negative 2 pounds).

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

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

[0290] As shown in FIG. 7, the securing mechanism can be a radially outward protrusion 240 (of the first portion 150) configured to impact the proximal end 242 of the second portion 152 such that moving the first portion 150 distally overcomes a force threshold to deform the first portion 150 and / or the second portion 152 and enable the radially outward protrusion 240 to move distally relative to the proximal end 242 of the second portion 152. The radially outward protrusion 240 is configured to deform the second portion 152 into an elliptical shape to enable the first portion 150 to move distally relative to the second portion 152.

[0291] FIG. 24 illustrates another securing 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 the interference portion 266 shown inside the dashed circle in FIG. 24.

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

[0293] In some embodiments, the first portion 150 includes a tapered portion 262. When the interference section of the first portion 150 moves distally past the interference region 266, the tapered portion 262 causes the system such that the interference portion 266 no longer hinders the distal movement of the first portion 150.

[0294] The second portion 152 can also have a tapered portion 263. The tapered portion 263 can be formed on the inner surface of the second portion 152 such that the inner size increases when measured from proximal to distal along the tapered portion 263.

[0295] The interference portion 242 of the second portion 152 can include a ramp portion (as shown in FIG. 24) to assist with the deformation described above. The interference section of the first portion 150 is positioned proximal to the interference section of the second portion 152.

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

[0297] Any of the features described in the situations of FIGS. 24 to 32 can be applied to all aspects and embodiments specified in this specification. For example, the embodiments described in the situations of FIGS. 24 to 32 can be combined with the embodiments described in the situations of FIGS. 1 to 23 and FIGS. 33 to 70. Furthermore, any of the features of one embodiment can be combined partially or entirely independently with other embodiments described in this specification. For example, it may be possible to combine one, two, or three or more embodiments entirely or partially. Furthermore, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0298] FIG. 25 illustrates a cross-sectional view of a portion of one embodiment configured such that a needle holder (e.g., needle hub 162) resists distal movement relative to a second portion 152b of a first portion 150. The second portion 152b is similar to other second portions 150 (as shown, for example, in FIG. 7), except that the second portion 152b includes a flexure arm 276 that is at least part of a fixing mechanism. The flexure arm 276 is releasably coupled to the needle holder to releasably fix the first portion 150 to the second portion 152b in a proximal starting position (as shown in FIG. 7).

[0299] A needle 156 (shown in FIG. 7) is releasably coupled to be storable in the first portion 150 by a needle holder 162. The needle holder 162 is configured to resist distal movement relative to a second portion 152b of the first portion 150 by a chamfer and / or a ramp portion 278 that interferes with the flexure arm 276. Pushing the first portion 150 distally requires overcoming the force necessary to deflect the flexure arm 276 outward so that the flexure arm 276 moves away from the ramp portion 278.

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

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

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

[0303] Ring 282 can be fixed between the first part 150 and the second part 152 of the nested assembly 132. Ring 282 can be wound around the outer periphery of the first part 150 such that Ring 282 is rested on the proximal end portion of the second part 152, and can be positioned proximally with respect to the second part 152.

[0304] Ring 282 enables a weak coupling between the first part 150 and the second part 152 while the first part 150 is in the proximal starting position. In FIG. 27, the system is configured such that moving the first part 150 to the distal position breaks the weak coupling (e.g., detent 280).

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

[0306] FIG. 27 also includes a magnet system 290. Magnet system 290 includes a magnet and a metallic element that is positioned sufficiently close such that the magnet is attracted to the metallic element (e.g., a metallic disc). For example, the second part 152 can include the magnet and the first part 150 can include the metallic element. In some embodiments, the second part 152 can include the metallic element and the first part 150 can include the magnet.

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

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

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

[0310] FIG. 31 illustrates a side view of a nested assembly 132e having a first portion 150e and a second portion 152e. The first portion 150e includes a radially outward protrusion 286e configured to engage a radially inward ramp portion 296 positioned on the inner wall of the second portion 152e. When the user applies a distal axial force to the first portion 150e, the protrusion 286e collides with the ramp portion 296. The angle of the ramp portion rotates the first portion 150e relative to the second portion 152e. This rotation resists the distal force and acts as a locking mechanism. When the protrusion 286e moves beyond the distal end of the ramp portion 296, the ramp portion 296 no longer rotates and thus 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. This structure aids in ensuring that the compressive force generated by a person pushing a part of the system distally results in reliable performance. One challenge with relying on people to push the system downward to generate an appropriate force is that the input force can vary significantly by the user. Even a single user can 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. The motor can provide a reliable input force. The motor also enables the force to be varied in different sections of the path from the proximal starting position to the distal position.

[0313] Figures 28 - 30 illustrate embodiments of nested assemblies 132c, 132d that include motors 290c, 290d for driving the needle 156 and / or the glucose sensor 138 into the skin. The motors 290c, 290d can be linear actuators that use 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 parts 150c, 150d of the nested assemblies 132c, 132d, the nested assemblies 132c, 132d, the sensor module 134, and / or the sensor 138. The motors 290c, 290d can include an internal battery to supply electricity to the motors 290c, 290d.

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

[0315] Figures 29 and 30 illustrate side cross-sectional views of another embodiment of a motor. In this embodiment, the rod 294 of the motor 292d is coupled to be stationary with respect to the second portion 152d of the nested assembly 132d. The motor 292d is coupled to and stationary with respect 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 with respect 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 skin of the recipient, and the glucose module 134 is coupled to the base 128. As illustrated in FIGS. 29 and 30, the embodiment is needleless. Similar embodiments can include a needle.

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

[0317] In some embodiments, the protrusion 302 of the second portion 152 engages the aperture 304 of the first portion 150. The protrusion 302 can be oriented proximally to latch engage the aperture 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 in length, and / or less than 50 millimeters in length. The protrusion 302 can include an end portion that protrudes at an angle with respect to the central axis of the majority of the protrusion 302. This angle can be at least 45 degrees, at least 75 degrees, less than 110 degrees, or less than 135 degrees.

[0319] Coupling the protrusion 302 to the hole 304 can permanently lock the first portion 150 in a downward position (distal to the proximal starting position and within 3 millimeters of the distal position) while the needle 156 is in the stored state. This locking can prevent the system from being reused and can also prevent injury by needle puncture.

[0320] Any of the features described in the context of FIG. 23 can be applied to all aspects and embodiments specified herein. For example, the embodiments described in the context of FIG. 23 can be combined with the embodiments described in the contexts of FIGS. 1-22 and FIGS. 24-70. Further, any of the features of one embodiment can be combined partially or wholly independently with other embodiments described herein. For example, it may be possible to combine one, two, or three or more embodiments wholly or partially. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0321] Interconnection Referring now to FIG. 4, in many embodiments, the electronic device unit 500 drives a voltage bias through the sensor 138 so that the current can be measured. Accordingly, the system can analyze the glucose level of the recipient. The reliability of the electrical connection between the sensor 138 and the electronic device unit 500 is extremely important for accurate sensor data measurement.

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

[0323] The electrical connection must be mechanically stable. Relative movement between components of the electrical system can create signal noise, which can prevent accurate glucose data from being obtained.

[0324] A low-resistance electrical connection is more power-efficient. Power efficiency can help maximize the battery life of the electronic device unit 500.

[0325] In embodiments where the recipient or caregiver must compress the electrical interconnect and / or the seal 192, minimizing the required force increases user satisfaction. Reducing the force applied by the user makes the transmitter easier to install. If the required force is too great, the user and caregiver may not be able to apply sufficient force inadvertently, which can jeopardize the reliability and performance of the system. The force that the user must apply to couple the electronic unit 500 to the base 128 and the sensor module 134 is strongly affected by the force required to compress the interconnect. Thus, there is a need for an electrical interconnect having a smaller compression force.

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

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

[0328] FIG. 33 illustrates a perspective view of the skin sensor assembly just before the electronic device unit 500 (e.g., a transmitter) is snapped onto the base 128. Coupling the electronic device unit 500 to the base 128 can compress the seal 192 to prevent the entry of fluid and can also compress the interconnect (e.g., spring 306) to create an electrical connection 310 between the glucose sensor 138 and the electronic device unit 500.

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

[0330] Accordingly, creating the electrical connection 310 and / or coupling the electronic device unit 500 to the base 128 can "activate" the electronic device unit 500, enabling the electronic device unit 500 to wirelessly transmit information to other devices 110-113 (shown in FIG. 1) and / or to prepare for such wireless transmission. U.S. Patent Application Publication No. US2012 / 0078071 (A1) includes additional information regarding the activation of a transmitter. The entire content of U.S. Patent Application Publication No. US2012 / 0078071 (A1) is incorporated herein by reference.

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

[0332] The 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 positioned at the bottom of the electronic device module 500. The rigid electronic device module 500 and the 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 can have a helical shape. The springs 306 can be coil springs or leaf springs.

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

[0335] Some embodiments use a spring load 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 electronic device unit 500. The receptacle can be electrically coupled to the sensor 138 such that pressing the electronic device unit 500 against the spring load pin system electrically couples the electronic device unit 500 and the sensor 138.

[0336] Mill-Max Mfg. Corp. (“Mill-Max”) of Oyster Bay, New York, U.S.A. manufactures a spring load pin system having a nickel gold plated brass alloy shell. One Mill-Max spring load pin system has a stainless steel spring and a part number 0926-1-15-20-75-14-11-0.

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

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

[0339] Figure 34 illustrates a perspective view of the sensor module 134. The protrusion 308 can secure the spring 306 to the sensor module 134. (Not all protrusions 308 are necessarily labeled for clarity in Figure 34.) The protrusion 308 can protrude distally.

[0340] At least three, at least four, and / or less than ten protrusions 308 can be configured to contact the outer circumference 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 that couples the electronic device unit 500 to the base 128 can press the spring 306 against the sensor 138 and electrically couple the spring 306 to the sensor 138. The sensor 138 can extend between at least two of the protrusions 308.

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

[0342] Referring now to FIGS. 33 and 34, system 600 can include a sensor module housing 312, 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 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 connections.

[0343] The sensor module housing 312 includes at least two proximal protrusions 308 positioned around the outer perimeter 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 a base 128. The base 128 includes an adhesive 126 configured to couple the base 128 to the recipient's skin.

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

[0346] Referring now to FIGS. 33 and 35-38, system 600 can include sensor module housings 312d, 312e, glucose sensors 138a, 138b having a first section 138a configured for subcutaneous sensing and a second section 138b mechanically coupled to sensor module housings 312d, 312e, and electrical interconnects (e.g., leaf springs 306d, 306e) mechanically coupled to sensor module housings 312d, 312e and electrically coupled to glucose sensors 138a, 138b. Instead of sensor module 134 shown in FIG. 7, sensor modules 134d, 134e can be used. Leaf springs 306d, 306e can be configured to flex in response to the electronic device unit 500 coupling to 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 vertically. In many embodiments as used herein, 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 of 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 at one end (such that the leaf spring is a cantilever spring).

[0348] As shown in FIGS. 35 and 36, sensor module housing 312d includes a proximal projection 320d having a channel 322d in which at least a portion of the second section of glucose sensor 138b is positioned. Channel 322d positions the first region of glucose sensor 138b such that the region is electrically coupled to 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 projects proximally to electrically couple to the electronic device 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 projection 320d. The leaf spring 306d projects proximally to electrically couple to the electronic device unit 500 (shown in FIG. 33). The seal 192 is configured to prevent fluid from entering the leaf spring 306d.

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

[0351] Referring now to FIGS. 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. The distal portion of the leaf spring 306e is positioned within the channel 322e such that the proximal portion of the leaf spring 306e projects 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] FIGS. 36 and 38 illustrate two leaf spring configurations. Other embodiments may use other types of leaf springs. The elements shown in FIGS. 33 - 38 can be combined.

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

[0355] Reducing the force required to compress the interconnects 306, 306d, 306e (e.g., when the electronic device 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 electronic device unit 500 to the base 128 is quite high. In some cases, if the required force is too high, some users may not be able to couple the electronic device unit 500 to the base 128. Therefore, there is a need for a system that requires less force to couple the electronic device 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 electronic device 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 an active compression range.

[0357] In some embodiments, the interconnects 306, 306d, 306e may require a compression force of less than 1 pound to compress the spring 20 percent from its relaxed position, which is a substantially uncompressed position. In some embodiments, the interconnects 306, 306d, 306e may require a compression force of less than 1 pound to compress the spring 25 percent from its relaxed position, which is a substantially uncompressed position. In some embodiments, the interconnects 306, 306d, 306e may require a compression force of less than 1 pound to compress the spring 30 percent from its relaxed position, which is a substantially uncompressed position. In some embodiments, the interconnects 306, 306d, 306e (changing the dependency to the independent claims) may require a compression force of less than 1 pound to compress the spring 50 percent from its 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 millimeter, and / or less than 4 millimeters. The seal 192 can have a height of 2.0 millimeters, at least 1 millimeter, and / or less than 3 millimeters. In some embodiments, the springs 306, 306d, 306e protrude (e.g., distally) at least 0.2 millimeter and / or less than 1.2 millimeters from the top of the seal 192 in their relaxed state (i.e., substantially uncompressed state).

[0359] When the electronic device unit 500 is coupled to the base 128, the compression of the springs 306, 306d, 306e can be 0.62 millimeter, at least 0.2 millimeter, less than 1 millimeter, and / or less than 2 millimeters by a 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 electronic device unit 500 is created at the factory. This electrical connection can be sealed at the factory to prevent the entry of fluid, but it can endanger the integrity of the electrical connection.

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

[0362] Referring to FIGS. 4, 6, 7, and 33 below, one key electrical connection is between the electronic device unit 500 (e.g., a 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 robust to enable connecting the sensor module 134 to the base 128 and then connecting the base 128 and the sensor module 134 to the electronic device unit 500 (e.g., a transmitter). A stable sensor module 134 enables coupling the sensor module 134 to the base 128 without generating 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). These electrical connections can also be made by the recipient or caregiver when the user attaches the electronic device unit 500 to the base 128 and / or the sensor module 134.

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

[0365] Any of the features described in the context of FIGS. 33-38 can be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of FIGS. 33-38 can be combined with the embodiments described in the context of FIGS. 1-32 and FIGS. 39-70. Further, any of the features of one embodiment can be combined, in part or in whole, independently of the other embodiments described herein. For example, it may be possible to combine one, two, or three or more embodiments, in whole or in part. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0366] Referring now to FIG. 33, the battery 314 can be positioned inside the electronic device unit 500 or can be part of the base 128. Maximizing the life of the battery 314 is important for many reasons. For example, the electronic device unit 500 can 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 can use the electronic device unit (e.g., to measure an analyte) can be sharply reduced.

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

[0368] As described in the situation of FIG. 33, creating the electrical connection 310 and / or coupling the electronic device unit 500 to the base 128 can wake up the electronic device unit 500 (e.g., the transmitter) from the sleep mode. For example, conductive members (e.g., of the sensor module 134 and / or the base 128) can contact the electrical contacts of the electronic device unit 500 (e.g., the electrical contacts of the battery of the electronic device unit 500), which can wake up the electronic device unit 500 from the sleep mode and / or start allowing power to flow from the battery. The conductive members of the sensor module 134 and / or the base 128 can be battery jumpers that close the circuit to allow electricity to flow from the battery to other parts of the electronic device unit 500.

[0369] Therefore, creating the electrical connection 310 and / or coupling the electronic device unit 500 to the base 128 can "wake up" the electronic device unit 500 and enable the electronic device unit 500 to wirelessly transmit information to other devices 110-113 (shown in FIG. 1) and / or prepare for such wireless transmission. U.S. Patent Application Publication No. US2012 / 0078071 (A1) includes additional information regarding the wake-up (e.g., start-up of the transmitter) of the electronic device unit 500. The entire content of U.S. Patent Application Publication No. US2012 / 0078071 (A1) is 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 (such as those shown in FIGS. 34-40) described herein. 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 embodiments described in the context of FIG. 7 and can also 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 to FIGS. 65-70 below, the sensor module 134j includes a conductive jumper 420f (e.g., an electrical connection that can include metal). The conductive jumper 420f is configured to electrically couple two electrical contacts 428a, 428b of the electronic device unit 500 (e.g., a transmitter) in response to coupling the electronic device 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. The first spring 306f of the jumper 420f can be coupled to the first contact 428a, and the second spring 306f of the jumper 420f can be coupled to the second contact 428b, which can complete an electrical circuit to enable the battery to provide electricity to the electronic device 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] As shown in FIG. 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 perpendicular to the sensor 138b such that the conductive link 422f intersects over a portion of the sensor 138b positioned inside the encapsulation region (e.g., inside the encapsulant 192).

[0374] FIG. 67 illustrates a perspective view of a portion of a sensor module 134k similar to the sensor module 134j shown in FIGS. 65 and 66. FIG. 68 illustrates a top view of the sensor module 134k shown in FIG. 67.

[0375] Referring to FIGS. 67 and 68 below, the sensor module 134k includes different types of conductive jumpers 420g, which include two helical springs 306g conductively coupled by a conductive link 422g. The conductive link 422g is configured to cross above or below the sensor 138b (shown in FIG. 34). As shown in FIGS. 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 electronic device unit 500 to initiate an electrical current flow within the electronic device unit 500. Thus, the conductive jumper 420g can "activate" the electronic device unit 500. The conductive jumper 420g can be used with any of the sensor modules described herein.

[0376] FIGS. 69 and 70 illustrate perspective views of the electronic device unit 500 immediately before the electronic device unit 500 is coupled to the base 128. As shown in FIG. 70, the electronic device 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 electronic device 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 electronic device unit 500.

[0377] Coupling the electronic device unit 500 to the sensor module 134k and / or the 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 electronic device unit 500 to the sensor module 134k and / or the base 128 can electrically and / or mechanically couple the electrical contacts 428c, 428d to any other type of electrical connection 426 (such as that shown in FIG. 67) between the springs 306, 306d, 306e (shown in FIGS. 34-38) and / or the sensor 138 (shown in FIG. 39) and the electronic device unit 500.

[0379] Any of the features described in the context of FIGS. 65-70 can be applied to all aspects and embodiments specified herein. For example, the embodiments described in the context of FIGS. 65-70 can be combined with the embodiments described in the context of FIGS. 1-64. Further, any of the features of one embodiment can be combined, in part or in whole, independently of the other embodiments described herein, for example, it may be possible to combine one, two, or three or more embodiments in whole or in part. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can 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. A section 138a (shown in FIG. 34) of the glucose sensor 138 (labeled in FIG. 7) configured for subcutaneous sensing can be disposed within the channel 330 (as shown in FIG. 40).

[0381] The needle 156 can guide the sensor 138 into the recipient's skin. The distal portion of the sensor 138 can be positioned within the channel 330 of the needle 156. At times, the distal end of the sensor 138 protrudes from the needle 156 as the sensor 138 and the needle 156 are inserted into the recipient, snagging on the recipient's tissue. As a result, the sensor 138 may be distorted and not inserted deeply enough into the subcutaneous tissue. In other words, in some embodiments, the sensor wire must be disposed within the channel 330 of the C-shaped needle 156 that is being guided into the tissue and must be held within the channel 330 during deployment.

[0382] The risk that the sensor 138 protrudes from the channel 330 (and thus cannot be properly inserted 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). The position B334 in FIG. 42 illustrates a sensor protruding from the channel 330.

[0383] The angle 338 and offset 336 cause an elastic deformation of the sensor 138, creating a force that presses the sensor 138 against the bottom of the channel 300 (as shown by position A332 in FIG. 42), while avoiding the potentially harmful effects of inappropriate angles 338 and offsets 336. The angle 338 and offset 336 also cause a plastic deformation of the sensor 138, assisting in shaping the sensor 138 in a way that minimizes the risk that the sensor 138 is 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 positioning a portion of the sensor 138 within the channel 330 of the needle 156.

[0385] As shown in FIG. 39, a portion of the glucose sensor 138b (also labeled in FIG. 34) can be disposed in the distally facing channel 342 (which is a tunnel in some embodiments). This channel 342 can assist in orienting the glucose sensor 138b towards the channel 330 (shown in FIG. 43) of the needle 156.

[0386] As shown in FIG. 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 before coupling the sensor 138 to the sensor module housing 312 (shown in FIG. 34) and / or before disposing a portion of the sensor 138 within the channel 330 (shown in FIG. 43) of the needle 156.

[0387] Referring now to FIG. 41, an angle 338 that is less than 110 degrees can result in a 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 338 that is less than 125 degrees can result in a failed deployment (e.g., due to 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) can reduce the likelihood of a 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 within the channel 330 of the needle 156. In this manufacturing method, the angle is measured from the central axis of 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 the recipient. According to this angle measurement, an angle greater than 70 degrees can cause the deployment to fail (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 greater than 55 degrees can cause the deployment to fail (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) can reduce the likelihood of deployment failure. In some embodiments, the angle is at least 25 degrees and / or less than 60 degrees.

[0389] An offset 336 that is too large (shown in FIG. 40) can cause the sensor 138 to not be securely held in the channel 330 (shown in FIG. 42). In other words, a large offset 336 will cause the sensor 138 to be positioned not securely at position A332 but at position B334. An offset 336 that is too small can exert too much stress on the sensor 138 and thus break the sensor 138. Considering these factors, 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 bending of sensor 138 can include stress relaxation. For example, the bending of sensor 138 can be encapsulated within a polymer tube or an elastomeric tube to provide stress relaxation to sensor 138. In some cases, all of the bending of sensor 138 can be encapsulated within a polymer tube or an elastomeric tube. In some embodiments, the tube is composed of a soft polymer. The polymer tube or elastomeric tube can encapsulate sensor 138 by a heat shrinkage process. In some embodiments, silicone gel can be applied to the sensor at channel 342 (shown in FIG. 39), or near it, 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 0.010 inches or more and / or 0.015 inches or less. The width 344 of channel 330 is measured at the narrowest width at which glucose sensor 138 can be positioned.

[0392] Referring now to FIG. 40, the funnel 182 of the base 128 can assist in guiding the needle 156 and / or the glucose sensor 138 into the hole 180. The funnel 182 and the hole 180 can assist in securing the sensor 138 to the C-shaped needle 156 during storage and deployment. For example, the hole 180 can be made small enough such 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 role of the funnel 182 and the hole 180 is to support the needle 156 and / or the sensor 138 against buckling forces during insertion into the recipient of the needle 156 and / or the sensor 138.

[0394] The funnel 182 and the aperture 180 also protect against accidental needlestick injuries (since they are very small, for example, preventing a finger from reaching the needle 156 before the needle is deployed).

[0395] The sensor module 134 cannot pass through the funnel 182 and the aperture 180 (for example, 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 sensors 138 from passing through the aperture 180 and ensure that the sensors 138 are 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 FIGS. 39-43 can be applied to all aspects and embodiments specified herein. For example, the embodiments described in the context of FIGS. 39-43 can be combined with the embodiments described in the context of FIGS. 1-38 and FIGS. 44-70. Additionally, any of the features of one embodiment can be combined, in whole or in part, independently of the other embodiments described herein, for example, it may be possible to combine one, two, or three or more embodiments in whole or in part. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0397] Excluding needles Some embodiments use a needle to assist in inserting a glucose sensor into subcutaneous tissue. However, some people fear needles. In addition, the disposal of needles may require the use of a sharps disposal container that is not readily available.

[0398] While many embodiments do not use a needle to insert the sensor, this can assist people in feeling more comfortable with the insertion of the sensor and also eliminate the need to use a sharps disposal container to dispose of the applicator or a portion thereof.

[0399] U.S. Patent Application Publication No. US2011 / 0077490(A1), U.S. Patent Application Publication No. US2014 / 0107450(A1), and U.S. Patent Application Publication No. US2014 / 0213866(A1) describe some needleless embodiments. The entire contents of U.S. Patent Application Publication No. US2011 / 0077490(A1), U.S. Patent Application Publication No. US2014 / 0107450(A1), and U.S. Patent Application Publication No. US2014 / 0213866(A1) 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 FIGS. 1-50 can be used with or without a needle. For example, the embodiment shown in FIG. 7 can be used in a very similar manner without including the needle 156. In this needleless embodiment, moving the first portion 150 distally drives the distal portion of the glucose sensor 138 into the skin (without using the needle 156). In a needleless embodiment, the sensor 138 can have sufficient buckling resistance so that the sensor 138 does not buckle when supported by the aperture 180. Sharpening the distal tip of the sensor 138 can also facilitate needleless insertion into the recipient.

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

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

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

[0404] The embodiments illustrated in FIGS. 56 - 58 can be integrated into the applicator system 104 shown in FIGS. 2 and 3.

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

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

[0407] The first portion 150g (e.g., a pusher) of the nested assembly 132g can include a distal projection 352 that supports a substantially horizontal section of the glucose sensor 138g (e.g., when the glucose sensor 138g protrudes from the sensor module 134g). The end of the distal projection 352 can include a groove 354 in which at least a portion of the glucose sensor 138g is positioned. The groove 354 can assist in holding the glucose sensor 138g. The distal projection 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 assist in guiding the distal end of the glucose sensor 138g into the hole 180g in the base 128g. The hole 180g can support the sensor 138g radially when the sensor 138g is inserted into the recipient's tissue.

[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 proper distal direction.

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

[0411] The nested assembly 132g (e.g., an applicator) does not include a needle. As a result, there are no sharp objects in the applicator, which eliminates the need for protection against sharp objects after use. This design feature eliminates the need for a storage spring or a needle hub. The distal end of the sensor wire 138g can be sharpened to the extent that it reduces 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 the distal end of the first portion 150g. The glucose sensor 138g and the sensor module 134g can be coupled to the distal end of the first portion 150g such that the first portion 150g is fixed in a proximal starting position by an interference portion between the first portion 150g and the second portion 152g of the nested assembly 132g and / or such that the first portion 150g is moved distally relative to the second portion 152g by applying a distal force greater than the separation threshold of the interference portion (e.g., until the sensor 138g is inserted into tissue and the sensor module 134g is coupled to the base 128g), so that the applicator does not require a spring, a needle, or a needle hub.

[0413] Figures 46 and 47 illustrate a similar, needleless 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 directs the sensor 138h distally such that the glucose sensor 138h includes a bend that is at least 45 degrees and / or less than 135 degrees. The communication path cover 362 secures the glucose sensor 138h within the distally oriented channel 358.

[0414] The embodiments illustrated in FIGS. 44-47 can be integrated into the applicator system 104 shown in FIGS. 2 and 3. Referring to FIG. 2 below, an electronic device unit 500 (e.g., a transmitter having a battery) can be removably coupled to a sterile barrier shell 120. The remaining applicator system 104 can be sterilized and then the electronic device unit 500 can be coupled to the sterile barrier shell 120 (so that the electronic device unit 500 is not sterilized by the remaining applicator system 104).

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

[0416] Any of the features described in the context of FIGS. 44-47 can be applied to all aspects and embodiments specified herein. For example, the embodiments described in the context of FIGS. 44-47 can be combined with the embodiments described in the context of FIGS. 1-43 and FIGS. 48-70. Further, any of the features of one embodiment can be combined, in part or in whole, independently of the other embodiments described herein, for example, it may be possible to combine one, two, or three or more embodiments in whole or in part. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0417] In some embodiments, sensor 138 can be deployed (e.g., into a recipient's skin) in response to coupling an electronic device unit 500 (e.g., a transmitter) to base 128. Sensor 138 can be any type of analyte sensor (e.g., a glucose sensor).

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

[0419] One way to reduce the possibility of premature sensor deployment is for the system to include an initial resistance (e.g., for coupling electronic device unit 500 to base 128). The initial resistance can require a force buildup before it can be overcome. When the initial resistance is overcome, sensor 138 is typically deployed faster than in cases without an initial resistance (e.g., by a force buildup that can be less than at least 0.5 pound, 1 pound, and / or 5 pounds). This rapid deployment can reduce the pain associated with the sensor insertion process.

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

[0421] Figures 56-58 illustrate a first portion 150 that deploys sensor 138 into the skin of a recipient. In some embodiments, the first portion 150 is replaced with the electronic device unit 500 shown in FIG. 4 such that coupling the electronic device unit 500 to the base 128 presses 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 electronic device unit 500 such that moving the electronic device unit distally with respect to the second portion 152 and / or coupling the electronic device unit 500 to the base 128 requires overcoming an initial resistance of the protrusion 240.

[0422] In some embodiments configured such that sensor 138 is deployed (e.g., into the recipient's skin) in response to coupling the electronic device unit 500 to the base 128, the nested assembly 132b is not used. Instead, features of the base 128 provide an initial resistance for coupling the electronic device unit 500 to the base 128. The locking feature 230 of FIG. 33 is used for different purposes in some other embodiments, but the locking feature 230 of the base 128 can be coupled with a corresponding feature of the electronic device unit 500. This coupling may require overcoming an initial resistance.

[0423] Any of the features and embodiments described in the context of FIGS. 1-70 can apply to all aspects and embodiments where sensor 138 is deployed (e.g., into the recipient's skin) in response to coupling an electronic device unit 500 (e.g., a transmitter) to the base 128. Vertical locking

[0424] After inserting a glucose sensor using a nested assembly (e.g., an applicator), the needle used to insert the glucose sensor can accidentally penetrate another person. To protect against this risk, the nested assembly can protect people from subsequent needle stick injuries by preventing the first part of the nested assembly from moving distally relative to the second part after the sensor has been inserted into the recipient.

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

[0426] The proximal protrusion 364 is biased such that when the proximal protrusion 364 engages 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 part 150i first moves distally. When the first part 150i is in the distal end position, the spring can push the first part 150i to the second proximal position. Instead of returning to the starting proximal position, the proximal protrusion 364 catches on the lockout feature 366 (by the biasing of the proximal protrusion 364 and a notch 368 facing distally in the lockout feature 366).

[0428] When the proximal end of the proximal protrusion 364 is captured by the lockout feature 366, the strength of the proximal protrusion 364 prevents the first part 150i of the nested assembly 132i from moving distally a second time.

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

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

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

[0432] The first part 150i can include a lamp portion 370 that guides the proximal protrusion 364 along the first path. The distal protrusions (e.g., the lamp portion 370) of the first part 150i can bias the proximal protrusion 364 to enter the second path as the first part 150i moves proximally. The proximal protrusion 364 can be a flexure arm. The lock 366 can include a distally facing notch 368 that catches on the proximal end of the proximal protrusion 364.

[0433] As shown in FIGS. 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 FIGS. 48-50 can be applied to all aspects and embodiments identified herein. For example, the embodiments described in the context of FIGS. 48-50 can be combined with the embodiments described in the context of FIGS. 1-47 and FIGS. 51-70. Further, any of the features of one embodiment can be combined, in whole or in part, independently of the other embodiments described herein, for example, it may be possible to combine one, two, or three or more embodiments in whole or in part. Further, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0435] Double spring assembly Partial sensor insertion can lead to suboptimal sensing. In some cases, partial sensor insertion can cause a needlestick accident (due to the needle not being stored in the protective housing). Therefore, there is a need for a system that ensures complete sensor insertion.

[0436] The embodiments illustrated in FIGS. 61-64 dramatically reduce the probability of partial sensor insertion by preventing sensor insertion until sufficient potential energy is stored in the system. The potential energy is stored in the first spring 402.

[0437] The system includes a number of items (e.g., base 128 and sensor module 134) from the embodiment illustrated in FIG. 7. The system includes optional needle 156 and needle hub 162. The embodiments illustrated in FIGS. 61-64 can also be configured to be needleless by removing needle 156, second spring 234, needle hub 162, and needle storage mechanism 158.

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

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

[0440] The nested assembly 132k can lock the third part 392 to the second part 152k in response to the third part 392 reaching a sufficiently distal position relative to the second part 152k. The protrusion 408 can engage the hole 410 to lock the third part 392 to the second part 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 sufficient distal position is at least 3 millimeters, at least 5 millimeters, and / or less than 30 millimeters distal relative to the proximal starting position.

[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 protrusion 412 (e.g., a distal protrusion) can engage the hole 414 (e.g., on a surface within ±30 degrees perpendicular to the 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 assist in inserting the sensor into the recipient's skin. In embodiments that include the needle 156, the nested assembly 132k can include the needle storage 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., releases a latch on) the needle storage mechanism 158 to allow the second spring 234 to store the needle 156.

[0445] FIG. 61 illustrates a system for applying a skin sensor assembly 600 (shown in FIGS. 4-6) to a recipient's skin. The system includes a nested assembly 132k having a first portion configured to move distally along a path from a proximal starting position (e.g., the position shown in FIG. 61) to a distal position (e.g., the position shown in FIG. 64) relative to a second portion 152k, 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 nested assembly 132k can 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 within 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, a first spring 402 is positioned between the third portion 392 and the second portion 152k such that compressing the first spring 402 moves the third portion 392 distally relative to the second portion 152k. The first spring 402 can be a metal coil spring and / or a metal conical spring. In some embodiments, the first spring 402 is a feature molded 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 nested assembly 132k can be configured such that the first spring 402 is not compressed at the proximal starting position and / or is not compressed during storage. In some embodiments, the nested assembly 132k is configured such that the first spring 402 is not compressed by more than 15 percent at the proximal starting 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 the needle 156 do not include the needle hub 162. In these embodiments, the second spring 234 can be positioned between the second portion 152k and the first portion 150k such that compressing the second spring 234 moves the first portion 150k distally relative to the second portion 152k and the second spring 234 presses the first portion 150k proximally relative to the second portion 152k to store the 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 starting position. For example, the second spring 234 can be compressed at the factory while assembling the nested assembly 132k such that the second spring 234 is already compressed (sufficiently compressed to store the needle 156) when the user receives the nested assembly 132k.

[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 (e.g., in the context of the embodiment of FIG. 7).

[0452] In some embodiments, movement of the sensor module 134 (e.g., analyte sensor module) and sensor 138 (e.g., 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 FIGS. 7-11).

[0453] At the proximal starting position of the nested assembly 132k, the first portion 150k can latch to the second portion 152k. The system can be configured to unlatch the first portion 150k from the second portion 152k by moving the third portion 392 distally relative to the second portion 152k.

[0454] In some embodiments, a first proximal protrusion 394 having a first hook 396 passes through a first aperture 398 of the second portion 152k to latch the first portion 150k to the second portion 152k. The third portion 392 can comprise a first distal protrusion 404. The system can be configured to unlatch the first portion 150k from the second portion 152k by moving the third portion 392 distally relative to the second portion 152k to engage a ramp portion 406 and bend the first proximal protrusion 394.

[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 can be as described in the context of other embodiments herein. The sensor 138 can be coupled to the sensor module 134 while the first portion 150k is positioned at the proximal starting 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 a hole 414 in at least one 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, and the compressed first spring 402 is capable of pushing 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, triggering the needle storage mechanism 158, and enabling the second spring 234 to store the needle 156.

[0461] In yet another aspect, the present disclosure provides 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 device into the user's skin by a needle, as well as reliable storage of the needle after the sensor has been inserted, which features provide convenience to the user and, as well, predictability and reliability of the insertion mechanism. The reliability and convenience of a dual-spring based sensor insertion device having automatic insertion and automatic storage provide significant advancement in the field of sensor insertion devices. Further, 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 a nested assembly, such as a first portion and a second portion of a nested 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 nested assembly. For example, in some embodiments, the insertion spring can be integrally formed with a portion of the nested assembly, while the storage spring is a separate portion operably coupled to a portion of the nested assembly.

[0463] In some embodiments, rather than being configured to be compressed during energy impartation, one or both of the first spring and the second spring can be configured to be placed under tension during energy impartation. In these embodiments, the couplings between the spring and a portion of the nested assembly, as well as between the moving portions of the assembly (e.g., in a stationary state and during activation, deployment, and stowage), can be adjusted to drive and / or facilitate the desired activities and reactions within the system. In one embodiment that uses a stowed spring placed under tension to drive the insertion process, the stowed spring can be coupled to or integrally formed with a second portion of the nested assembly. In such an embodiment, the stowed spring can be pre-tensioned in a stationary state. In other such embodiments, the stowed spring can be not pre-tensioned in a stationary state and can be placed under tension during the sensor insertion process.

[0464] In some embodiments, one or both of the first spring and the second spring can be in a substantially non - energized state and / or non - stressed state when the system is in a stationary state. In some embodiments, one or both of the first spring and the second spring can be in an energized state and / or stressed state when the system is in a stationary state. As used herein, the term "energized" means that sufficient potential energy for performing desired activities and reactions within the system is stored in the spring. In some embodiments, the first spring can be partially energized in the stationary state such that a user can apply a lesser amount of force to fully energize the first spring. In some embodiments, the second spring can be partially energized in the stationary state (either in the stationary state or after energization by the user) such that the energy stored in the first spring can provide a force to energize the second spring. In some embodiments, the energy stored in the first spring can provide sufficient force to energize the second spring and at least retract the needle from the skin. In some embodiments, one or both of the first spring and the second spring can be compressed or have tension applied to 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% of the stationary state. In other embodiments, one or both of the first spring and the second spring can be compressed or have tension applied to 50% or less, 40% or less, 30% or less, 20% or less, 15% or less, 10% or less, 5% or less, or 0% of the stationary state.

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

[0466] Referring now to FIGS. 71 - 75, another embodiment of a system 104m for applying a skin - mounted 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 until sufficient potential energy is 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 a controlled speed, a controlled force, and an improved user experience.

[0467] System 104m can include a number of features from the embodiment illustrated in FIG. 7 (e.g., needle 156, base 128, and sensor module 134). System 104m can include alternative elements such as, but not limited to, needle hub 162m, second spring 234m, and needle storage mechanism 158m. The embodiment illustrated in FIGS. 71 - 75 can also be configured to be needle - free by removing the needle 156, second spring 234m, needle hub 162m, and needle storage 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 embodiments illustrated in FIGS. 61-64, including a first portion 150m, a second portion 152m, and a third portion 392m. The third portion 392m reaches a position sufficiently distal to the second portion 152m to compress the first spring 402m and accumulate sufficient energy in the spring 402m to drive the insertion of the sensor 138 (and in some embodiments the needle 156) into the skin of the recipient. Locking features 396m and 398m configured to releasably lock the first portion 150m to the second portion 152m until the third portion 392m reaches a position sufficiently distal to the second portion 152m; locking features 408m and 410m configured to lock the third portion 392m to the second portion 152m (e.g., to prevent proximal movement of the third portion 392m relative to the second portion 152m) in response to the third portion 392m reaching a position sufficiently distal to the second portion 152m; unlocking features 404m and 406m configured to unlock the locking features 396m and 398m after at least the third portion 392m is locked to the second portion 152m and / or after the first spring 402m is sufficiently compressed; locking features 412m and 414m configured to lock the first portion 150m to the second portion 152m in response to the first portion 150m reaching a position sufficiently distal to the second portion 152m to drive the sensor 138 (and in some embodiments the needle 156) into the skin of the recipient; and a needle storage 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) when the needle hub 162m reaches a position sufficiently distal such that the second spring 234m stores the needle 156.

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

[0470] In the embodiments 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. An integrally formed spring such as that illustrated in FIGS. 71-75 provides advantages including a reduction in the number of parts within the system and a reduction in the amount of the assembly process. The first spring 402m can be formed of molded plastic. As illustrated in FIG. 71, in the stationary state, the second spring 234m is also in a substantially non-energized state (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 formed of molded plastic. Such a configuration can simplify the manufacture and assembly of the system 104m while avoiding disadvantages and / or creep of the first spring 402m, the second spring 234m, or other system components 104m during storage and / or prior to deployment. Also contemplated in other embodiments is that 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 constructed 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 / inch.

[0472] The applicator system 104 can impart energy by moving one component relative to the other. For example, moving the third portion 392m distally relative to the second portion 152m can accumulate energy in the first spring 402m as the first spring is compressed relative to the first portion 150m when the second portion 152m is disposed 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 and enable the first portion 150m to move 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 opening. The sensor module 134 remains at the proximal starting position while the first spring 402m is being energized.

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

[0474] FIG. 74 illustrates a cross-sectional perspective view of applicator system 104m in a state where system 104m is activated by disengaging 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 the distal direction, together with the needle hub 162m and the sensor module 134. This movement compresses the second spring 234m and distally deploys the needle 156 and the sensor module 134 until the sensor module 134 engages the base 128 and the needle 156 extends distally beyond the base 128 to a distal insertion position. When the needle 156 and the 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 storage mechanism 158m (e.g., the proximal projection 170m, the unlocking feature 160m, and the latch 236m comprising the end 164m of the unlocking feature 160m and the overhang 166m of the first portion 150m) cooperate to release the latch 236m. Optionally, the user can hear a click sound after the second spring 243m is activated, and the click sound 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 in the proximal direction in reverse, while the first portion 150m remains in the distally deployed position together with the sensor module 134. The stored potential energy can be between 0.25 pounds and 4 pounds. In a preferred embodiment, the stored potential energy is about 1 to 2 pounds. FIG. 75 illustrates a cross-sectional perspective view of applicator system 104m in which the sensor module 134 is coupled to the base 128 in the distal deployment position and the needle hub 162m is stored in the proximal storage position.

[0476] A system configured in accordance with an embodiment can provide an intrinsically safe and storage-stable system for inserting a sensor. A spring in an unloaded state (i.e., substantially uncompressed and substantially unactivated state) cannot be prematurely launched. In fact, such a system can hardly perform an accidental launch without direct interaction from the user because the first spring or the second spring is in a substantially non-energized state during storage. Furthermore, the elements of the system are not exposed to changes in force or phase over time (such as creep, environmental, defects due to time-dependent loading conditions, etc.) compared to a pre-energized insertion device. Therefore, it is assumed that a system having a spring in a substantially uncompressed state before activation has storage stability. The first and second springs in a substantially uncompressed state are configured such that the substantially non-energized first spring 404m provides sufficient energy to drive the sensor from the proximal position to the distal position, and further, energy is transmitted to the second spring 234m to drive the needle to the fully retracted position, thereby providing a system.

[0477] Other embodiments can also be configured to achieve these advantages. For example, FIGS. 76-79 illustrate another embodiment of a system 104n for applying a sensor assembly on skin to a host's skin. The system 104n includes a number of features similar to the features of the embodiment illustrated in FIGS. 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 FIGS. 76-79, the first spring 402n is formed separately from the third portion 392n and is operably coupled to the third portion. The second spring 234n is formed separately from the needle hub 162n and is operably coupled to the needle hub. The first spring and / or the second spring can each be configured as a helical spring having a circular cross-section. In some embodiments, the first spring and / or the second spring can each be configured as a helical spring having a square or non-circular cross-section. The first spring and / or the second spring can be made 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 part of the applicator assembly. For example, in some embodiments, the first spring can be integrally formed with the first portion, without limitation. 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 made of 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 stationary state where both the first spring 402n and the second spring 234n are in a non-stressed and non-energy-imparted state. In the stationary state, the first portion 150n can be fixed relative to the second portion 152n, at least axially, while the third portion 392n is movable relative to the first portion 150n, at least distally. 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 (such as the locking features described in FIGS. 71-75, or similar features) that are coupled to or form part of the first portion 150n and the second portion 152n. The system 104n includes a subcutaneous component 134n removably coupled to the needle hub 162n. The subcutaneous component can include 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 / transmission assembly, or any other component suitably applied to the skin of the recipient, whether directly or indirectly, e.g., via an adhesive patch.

[0479] In the stationary state illustrated in FIG. 76, the subcutaneous component 134n is disposed at a proximal starting 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 stationary state, the distal end of the first spring 402n abuts against a surface facing proximally of the first portion 150n. Application of a force to the surface facing proximally of the third portion 392n moves the third portion 392n distally relative to the first portion 150n, compresses the first spring 402n, and thus imparts energy. In some embodiments, this process can be similar to the spring energy-imparting process described in connection with FIG. 71.

[0480] FIG. 77 illustrates a side cross-sectional view of the applicator system of FIG. 76 with energy imparted to the first spring 402n. When the third portion 392n has moved sufficiently distally to impart energy to 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., simultaneously or successively), the first portion 150n becomes 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 each other by cooperating locking features (e.g., locking features as described in FIGS. 71-75 or similar features) that are coupled to or form part of the third portion 392n and the second portion 152n, and the third portion and the second portion are configured to engage each other when the third portion 392n reaches a sufficiently distal position. The first portion 150n and the second portion 152n can be made movable relative to each other by a structure (not shown in FIGS. 76-79) configured to release the locking features that held them together in the stationary configuration shown in FIG. 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 fix the needle hub 162n relative to the first portion 150n while the system is in the stationary position and during energy impartation to the spring 392n.

[0481] FIG. 78 illustrates a side cross-sectional view of system 104n in a state where the first portion 150n and the second portion 152n are unlocked, activating the first spring 402n, and the energy stored therein enables the first portion 150n to be driven distally. The movement of the first portion 150n also biases the needle hub 162n (as well as the on-skin component 134n coupled to the needle hub 162n) distally, compresses the second spring 234n against the surface facing proximally to the second spring 152n, couples the on-skin component 134n to the base 128n, and drives the needle 156 to the distal insertion position illustrated in FIG. 78. When the needle hub 162n reaches a sufficient distal position to achieve these functions, the end of the release feature 160n contacts the ramp portion 170n of the second portion 152n, compressing the release feature 160n inwardly (towards 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 can be configured to be compressed inwardly (or otherwise released) by a relative rotational movement of certain components of the system, such as a torsional movement or other rotational movement of the first portion relative to the second portion. In some embodiments, one or more release features can extend in a direction substantially parallel to the axis of the system (or in addition to this) as shown in FIG. 78, can extend in a direction perpendicular to the axis of the system, and / or can extend circumferentially around the axis of the system.

[0482] FIG. 79 illustrates a side cross-sectional view of system 104n in a state where needle hub 162n is disengaged from engagement with overhang 166, activating second spring 234n, and enabling the energy stored therein to drive needle hub 162n in the proximal direction. As needle hub 162n is retracted to the proximal position, skin component 134n is decoupled from needle hub 162n and remains in the deployed position, coupled to base 128n.

[0483] Figures 80-85 illustrate another embodiment of a system 104p for applying a skin sensor assembly to the skin of a host. A sensor insertion system as illustrated in Figures 80-85 can provide enhanced predictability in the spring displacement of a second energized spring 234p, since the second spring 234p is already compressed. Such a configuration can help to appropriately ensure that the needle is stored at a sufficient distance from the skin. In some embodiments, a system incorporating a pre-energized storage spring can provide effective and reliable insertion and storage, while requiring less force for the user to apply than, for example, a system where both the insertion spring and the storage spring are substantially non-energized prior to deployment, making such a configuration more convenient for at least some users. Further, in some embodiments, a system incorporating one or more metal springs can provide effective and reliable insertion and storage, while requiring less force for the user to apply than a system where both the insertion spring and the storage spring are composed of plastic. System 104p includes a number of features similar to the features of the embodiment illustrated in Figures 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, a skin component 134n, and a base 128p). In the embodiment illustrated in Figures 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 composed of metal. Alternatively, in some embodiments, one or both of the first spring and the second spring can be integrally formed as part of an applicator assembly. For example, without limitation, 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.

[0484] FIG. 80 illustrates a side cross-sectional view of system 104p in a stationary state where the first spring 402p is in a substantially non-stressed and non-energized state, while the second spring 234n is pre-energized (e.g., compressed). In the stationary state illustrated in FIG. 80, the first portion 150p is locked to the second portion 152p so as to prevent proximal or distal movement of the first portion 150p relative to the second portion 152p of the first portion 150p. 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 removably fixed to the first portion 150p. The needle hub 162n can be fixed to the first portion 150p 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 in any suitable manner.

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

[0486] FIG. 81 illustrates a side cross-sectional view of the system 104p of FIG. 80 after the third portion 392n has moved to a sufficiently distal position to impart energy to 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 each other in any suitable manner, for example, by cooperating releasable locking features (e.g., the locking features described in FIGS. 76-79, or similar features) coupled to or forming part of the third portion 392p and the second portion 152p. Simultaneously with or substantially simultaneously (e.g., simultaneously or subsequently) with the third portion 392p locking to the second portion 152p, the unlocking features 404p and 406p (see FIGS. 84 and 85) cooperate to unlock the lock between the first portion 150p and the second portion 152p.

[0487] FIG. 82 illustrates a side cross-sectional view of the system 104p with the first spring 402p actuated to drive the first portion 150p in the distal direction. The movement of the first portion 150p also biases the needle hub 162p (and the on-skin component 134p coupled to the needle hub 162p) in the distal direction, couples the on-skin component 134p to the base 128p, and further drives the needle 156 distally past the distal end of the system 104p. When the needle hub 162p reaches the distal insertion position shown in FIG. 82, or substantially simultaneously therewith (e.g., immediately before, simultaneously, or subsequently), the end of the release feature 160p contacts the ramp portion 170p of the second portion 152p, compressing the release feature 160p inwardly (toward the central axis of the system 104p), unlocking the needle hub 162p from the first portion 150p, and releasing or actuating 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). Actuation of the second spring 234p biases the needle hub 162p in the proximal direction.

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

[0489] FIG. 84 illustrates a perspective view of the system 104p in a stationary state, showing the first portion 150p and the third portion 392p in cross-section to better illustrate certain parts 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 with the first portion 150p and the third portion 392p also shown in cross-section, with the first spring 402p energized but not yet activated.

[0490] Figures 86-88 illustrate another embodiment of a system 104q for applying a skin sensor assembly to a recipient's skin where 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 initiate needle insertion and storage in fewer steps. As an advantage, it is contemplated that a relatively smaller applicator size and a more predictable spring displacement of the first spring can be achieved since the first spring is already compressed, thereby assisting in ensuring proper needle insertion into the user's skin. In some embodiments, a system incorporating a pre-energized insertion spring can provide effective and reliable insertion and storage while requiring less force to be applied by the user compared to, for example, a system where both the insertion spring and the storage spring are substantially non-energized 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., a nested assembly 132q including a first portion 150q, a second portion 152q, and a third portion 392q, a needle hub 162q, a first spring 402q, a second spring 234q, a skin component 134q, and a base 128q). In system 104q, the first spring 402q is formed separately from and operatively coupled to the third portion 392q. The second spring 234q is formed separately from and operatively coupled to the needle hub 162q. The first spring and / or the second spring can be composed of metal. Alternatively, in some embodiments, one or both of the first spring and the second spring can be integrally formed as part of the applicator assembly.

[0491] FIG. 86 illustrates a side cross-sectional view of system 104q in a stationary state where the first spring 402q is already in an energy-imparted state, while the second spring 234q is in a substantially non-energy-imparted state (e.g., in a nearly uncompressed or non-stressed state and can be partially energy-imparted). In the stationary 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 detent features (e.g., the detent features described in FIGS. 76-79 or other suitable detent 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 axial relative movement between 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 detent features (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 stationary state illustrated in FIG. 80, the on-skin component 134q is disposed in a proximal starting 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 the deployment of system 104q, the locking feature that couples the first portion 150q to the second portion 152q is unlocked, decoupling these two portions, thereby enabling the first spring 402q to be released or actuated. The locking feature can be unlocked, for example, by a user-activated trigger mechanism such as a button disposed on or in the top or side surface of system 104q, or a twist-release feature configured to disengage the locking feature from the first portion 150q and / or the second portion 152q when the third portion 392q is rotated about the axis of the system. Some examples of the trigger mechanism are described in connection with FIGS. 92-104.

[0493] FIG. 87 illustrates a side cross-sectional view of system 104q after the first portion 150q and the second portion 152q have been unlocked. As can be seen in FIG. 87, the first spring 402q drives the first portion 150q in the distal direction as the first spring 402q extends. The movement of the first portion 150q also biases the needle hub 162q (and the skin component 134q coupled to the needle hub 162q) in the distal direction, couples the skin component 134q to the base 128q, compresses the second spring 234q, and drives the needle 156 distally past the distal end of system 104q. When the needle hub 162q reaches the distal insertion position shown in FIG. 87, or at or near the same time (e.g., immediately before, simultaneously, or subsequently), the end of the release feature 160q contacts the contact interface feature 170q of the second portion 152q, compressing the release feature 160q inwardly (towards the central axis of system 104q), unlocking the needle hub 162q from the first portion 150q, and actuating 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 the second spring 234q by the user or mechanism biases the needle hub 162q in the proximal direction, while the on-skin component 134q coupled to the base 128q remains in the deployed distal position. FIG. 88 illustrates a side cross-sectional view of the system 104q with the on-skin component 134q in the deployed position and the needle hub 162q stored in the proximal position.

[0495] Figures 89-91 illustrate another embodiment of a system 104r for applying a skin sensor assembly to a recipient's skin. The system 104r illustrated with reference to Figures 89-91 is intended to provide a predictable spring displacement of a first spring 402r that is already compressed, thereby assisting in ensuring proper insertion of a needle into the user's skin. Further, a compressed second spring 234r is intended to provide a predictable spring displacement and also assist in properly ensuring that the needle is properly stored 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 less force to be applied by the user than, for example, a system in which one or both of the insertion and retraction springs are substantially non-energized 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 Figures 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, a skin component 134r, and a base 128r). As illustrated in Figures 89-91, both the first spring 402r and the second spring 234r are pre-compressed. In the system 104r, the first spring 402r is formed separately from the third portion 392r and is operatively coupled to the third portion. The second spring 234r is formed separately from the needle hub 162r and is operatively coupled to the needle hub. The first spring and / or the second spring can be composed of metal. Alternatively, in some embodiments, one or both of the first spring and the second spring can be integrally formed as part of an applicator assembly.

[0496] FIG. 89 illustrates a side cross-sectional view of system 104r in a rest position where both the first spring 402r and the second spring 234r are pre-energized (e.g., fully compressed to drive the needle insertion and retraction processes). 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 (e.g., the locking features described in connection with FIGS. 80-83, or other suitable locking features) that are coupled to or form part of the first portion 150r and the second portion 152r. 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 features 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 at least axial relative movement between the third portion 392p and the second portion 152r. The third portion 392r and the second portion 152r can be locked together in any suitable manner, for example, by locking features (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 starting 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 the deployment of system 104r, the latching feature that couples the first portion 150r to the second portion 152r is unlatched, decoupling these two portions, thereby enabling the first spring 402r to be released or actuated. FIG. 90 illustrates a side cross-sectional view of system 104r after the first portion 150r and the second portion 152r have been unlatched. As can be seen in FIG. 90, the first spring 402r drives the first portion 150r in the distal direction as the first spring 402r extends or compresses. The movement of the first portion 150r also biases the needle hub 162r (and the on-skin component 134r coupled to the needle hub 162r) in the distal direction until the on-skin component 134r is coupled to the base 128r and the needle 156 reaches the distal insertion position beyond the distal end of the system 104r. When the needle hub 162r reaches the distal insertion position shown in FIG. 87, or at about the same time as that (e.g., immediately before, simultaneously, or subsequently), the end of the release feature 160r contacts the corresponding interface feature 170r of the second portion 152r, compressing the release feature 160r inward (toward the central axis of the system 104r), unlatching the needle hub 162r from the first portion 150r, and releasing or actuating the second spring 234r.

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

[0499] Figures 92-100 illustrate yet another embodiment of a system 104s for applying a skin sensor assembly to a recipient's skin, with safety features to prevent accidental firing of the sensor insertion device. System 104s includes a number of items similar to the features of the embodiments illustrated in Figures 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, a skin component 134s, and a base 128s). In system 104s, the first spring 402s is formed separately from the third portion 392s and can be operably coupled to the third portion 392s. The second spring 234s is formed separately from the needle hub 162s and can be operably coupled to the needle hub. The first spring and / or the second spring can be made of metal. Alternatively, in some embodiments, either or both of the first spring and the second spring can be integrally formed as part of an applicator assembly.

[0500] Figure 92 illustrates a side view of system 104s in a static state where the first spring 402s is in a non-stressed and non-energized state, but the second spring 234s is already energized (e.g., compressed). 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. System 104s also includes a trigger button 720 configured to activate the first spring 402s after the system is cocked. Figure 93 illustrates a side view of the applicator system 104s after being cocked but before being triggered.

[0501] FIG. 94 illustrates a cross-sectional perspective view of system 104s in a stationary state, showing a first spring 402s in a substantially uncompressed state. The cocking mechanism 702 includes a pair of proximally extending lever arms 704, each proximally extending lever arm having a radially extending angled tab 706. In some embodiments, the lever arms 704 can be integrally formed with a second portion 152s as shown in FIG. 94, while in other embodiments, the lever arms 704 can be separated from the second portion 152s and operably coupled to the second portion. In the stationary state illustrated in FIG. 94, the angled tab 706 extends through a distal opening 708 of the third portion 392s so as 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 as shown in FIG. 95, 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 arms 704 inwardly.

[0502] As sufficient force is applied distally to the third portion 392s (e.g., by the user's hand or thumb), the angled tab 706 deflects inwardly, disengages from engagement with the distal opening 708, and enables the third portion 392s to move distally relative to the second portion 152s. This enables the user to compress and energize the first spring 402s. As shown in FIG. 96, when the third portion 392s has reached sufficiently distally to compress the first spring 402s enough to drive the sensor into the recipient's skin, the angled tab 706 engages the proximal opening 710 of the third portion 392s and locks 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 to prevent proximal movement of the third portion 392s relative to the second portion 152s when engaging the proximal opening 710, such that the user can feel and / or hear when these components engage. In the configuration shown 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 does not deploy until further action is taken by the user.

[0503] FIG. 97 illustrates a cross-sectional view of the cocked but non-triggered state of system 104s. In this state, the first portion 150s is latched 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 latched together in any suitable manner, for example, by cooperating detent 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 detent feature 396s to decouple the first portion 150s from the second portion 152s when sufficiently depressed to a distal position by a user. The trigger button 720 can be operably coupled to the third portion 392s as shown in FIGS. 92-100, or can be integrally formed with the third portion, for example, as a lever arm formed in the proximal or side surface of the third portion. In some embodiments, the trigger button can be disposed at the top of the system (such that application of a distal-directed force triggers the system to activate) or at the side of the system (such that application of a radially inward-directed force perpendicular to the needle deployment direction triggers the system to activate).

[0504] FIG. 98 illustrates a side cross-sectional view of the system 104s in an energy imparted state where the trigger button 720 is fully depressed to radially inwardly flex the locking feature 396s against the protrusion 722, disengaging the locking feature from the opening 398s and disengaging the first portion 150s from the second portion 152s. As shown in FIG. 99, by depressing the trigger button 720, the first spring 402 is actuated to push the first portion 150s and the needle hub 162s distally, along with the skin-on component coupled thereto, until the skin-on component 134s is coupled to the base 128s. When the needle hub 162s reaches the distal insertion position shown in FIG. 99, or at or near the same time (e.g., immediately prior to, simultaneously with, or subsequent to), the corresponding release features of the needle hub 162s and the first portion 150s can be engaged (e.g., via the release features described in any of FIGS. 76-91, or any other suitable release feature) to unlock the needle hub 162s from the first portion 150s and to release or actuate the second spring 234s. Actuation of the second spring 234s biases the needle hub 162s proximally.

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

[0506] Any of the features described in the situation of any of FIGS. 61 to 99 can be applied to all aspects and embodiments specified in this specification. For example, the embodiments described in the situation of FIGS. 61 to 64 can be combined with the embodiments described in the situation of FIGS. 1 to 60 and FIGS. 65 to 70. As another example, any of the embodiments described in the situation of FIGS. 92 to 109 can be combined with any of the embodiments described in the situation of FIGS. 1 to 60 and FIGS. 65 to 91 and FIGS. 110 to 143. Furthermore, any of the features of one embodiment can be combined with other embodiments described herein either partially or wholly independently, for example, it may be possible to combine one, two, or three or more embodiments either wholly or partially. Furthermore, any of the features of one embodiment can be made optional with respect to other aspects or embodiments. Any aspect or embodiment of a method can be performed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system can be configured to perform a method of another aspect or embodiment.

[0507] Trigger mechanism and safety lock In some embodiments, applying sufficient force to energize the first spring to drive the insertion of the sensor also serves to activate the first spring. In other embodiments, energizing the first spring can be decoupled from activating the first spring, and separate activities are required for the user to energize (e.g., compress) the first spring and for part of triggering the deployment of the system.

[0508] For example, the embodiments illustrated in FIGS. 92-100 include a trigger mechanism in the context of an actuator to which a user applies energy. In such an embodiment, the user first cocks the system 104s to apply energy to the first spring 402s and then, in a separate activity, uses the trigger button 720 to trigger the activation of the first spring 402s. The latching feature is easily releasable by the user and, when combined with the trigger mechanism, enables use with one hand.

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

[0510] FIG. 101 illustrates a side view of one such applicator system 104t having a side trigger button 730. The system 104t can be configured to be substantially similar to the system 104q illustrated in the context of FIGS. 86-88 or the system 104r illustrated in the context of FIGS. 89-91, and like reference numerals indicate like parts. As can be seen in FIG. 101, the trigger button 730 is operably coupled to a third member 392t.

[0511] FIG. 102 illustrates another side view of 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 inwardly toward the central axis of the system 104t. The protrusion 732 is radially aligned with the locking feature 396t of the first portion 150t. When the user applies a lateral (e.g., radially inward) force to the trigger button 730, the protrusion 732 biases the locking feature 396t radially inward, disengaging the locking feature from engagement with a ledge feature 398t of the second portion 152t (which can be configured similar to the ledge locking feature 398p shown in FIGS. 84 and 85), and activating the first spring 402t. In other embodiments, the locking features 396, 398 can comprise a cooperating structure of a key / keyway mechanism that is configured to disengage when the features 396, 398 are in a particular orientation relative to each other (e.g., using a radially applied force, an axially applied force, a torsional motion or rotational force, or other types of activation).

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

[0513] The trigger mechanism as described in any of FIGS. 92-104 can be used in embodiments with a pre-energized actuator or insertion spring, as well as in embodiments with an actuator or insertion spring energized by the user.

[0514] In some embodiments, the sensor insertion system can include a safety mechanism configured to prevent premature energization and / or actuation of the insertion spring. FIGS. 105-109 illustrate one such system 104v incorporating a safety locking mechanism 750. FIG. 105 illustrates a perspective view of the system 104v. The system 104v can be configured to be substantially similar to any of the systems 104m, 104n, 104p illustrated in the context of FIGS. 71-87, and like reference numerals indicate like components. The safety locking 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 the system 104v, the release button 760 includes a lever arm integrally formed on a side of the third portion 392v, although other configurations (e.g., a top button) are contemplated. The release button can be configured to project radially from a side or top of the third portion, or can be configured with an outer surface that is coplanar wi...

Claims

**Claim 1** A system for applying a sensor assembly to a recipient's skin, comprising: A nested assembly having a first portion configured to move distally relative to a second portion along a path from a proximal starting position to a distal position; A sensor module coupled to the first portion, the sensor module including a sensor, electrical contacts, and a seal; A base coupled to the second portion so as to protrude from a distal end of the system, the base comprising an adhesive configured to couple the sensor module to the skin, wherein moving the first portion to the distal position couples the sensor module to the base. **Claim 2** The system of claim 1, wherein the base protrudes from the distal end of the system such that the sensor is positioned within the second portion while the system moves the first portion distally relative to the second portion to couple the sensor to the base. **Claim 3** The system of claim 2, wherein the sensor module is coupled to a distal portion of the first portion. **Claim 4** The system of claim 3, wherein the sensor is coupled to the sensor module while the first portion is positioned at the proximal starting position. **Claim 5** The system of claim 3 or 4, further comprising a needle coupled to the first portion such that the sensor and the needle move distally relative to the base and relative to the second portion, the system further comprising a needle release mechanism configured to retract the needle proximally. **Claim 6** The system of any one of claims 1-5, wherein the base comprises a distal protrusion having a first aperture, the distal protrusion being configured to reduce the skin's resistance to penetration. **Claim 7** The system of claim 6, wherein the sensor passes through the first aperture of the distal protrusion. **Claim 8** The system of claim 7, wherein a needle having a slot passes through the first aperture of the distal protrusion, and a portion of the sensor is positioned within the slot such that the needle moves the portion of the sensor distally relative to the base without displacing the portion of the sensor from the slot. **Claim 9** The system according to any one of claims 6-8, wherein the distal protrusion is convex such that, while the first portion moves distally relative to the second portion to prepare the skin for puncturing, the distal protrusion applies tension to the skin.

10. The system according to any one of claims 6-9, wherein the adhesive comprises a second aperture and the distal protrusion is at least partially positioned within the second aperture such that the distal protrusion can apply tension to at least a portion of the skin underlying the second aperture.

11. The system according to any one of claims 6-10, wherein the adhesive covers at least a majority of the distal protrusion.

12. The system according to any one of claims 6-11, wherein the distal protrusion protrudes at least 0.5 millimeter and less than 5 millimeters.

13. The system according to any one of claims 1-12, wherein the sensor module is coupled to the first portion while the first portion is in the proximal starting position and is positioned at least 5 millimeters from the base, and the system is configured such that moving the first portion to the distal position couples the sensor module to the base.

14. The system according to claim 13, wherein the sensor is coupled to the sensor module while the first portion is positioned in the proximal starting position.

15. The system according to claim 14, wherein the sensor is positioned within the second portion while the base protrudes from the distal end of the system.

16. The system according to any one of claims 1-15, wherein during a first portion of the path, the sensor module is stationary relative to the first portion and the base is stationary relative to the second portion, and during a second portion of the path, the system moves the first portion distally relative to the second portion, moves the sensor module toward the base, couples the sensor module to the base, and is configured such that the coupled sensor module and the base can be removed from the nested assembly.

17. The system according to any one of claims 1 to 16, wherein the sensor module comprises a first flexure arm that is horizontally oriented and coupled to the base.

18. The system according to claim 17, wherein the first flexure arm extends from an outer peripheral portion of the sensor module.

19. The system according to claim 17 or 18, wherein the base comprises a first proximal protrusion coupled to the first flexure arm so as to couple the sensor module to the base.

20. A first horizontal locking protrusion is coupled to an end portion of the first flexure arm, a second horizontal locking protrusion is coupled to the first proximal protrusion of the base, the first horizontal locking protrusion is positioned distally under the second horizontal locking protrusion so as to fix the sensor module to the base, and the system is configured such that moving the first part of the nested assembly to the distal position bends the first flexure arm and enables the first horizontal locking protrusion to move distally relative to the second horizontal locking protrusion. The system according to claim 19.

21. The system according to claim 19 or 20, wherein the base comprises a second proximal protrusion coupled to a second flexure arm of the sensor module.

22. The system according to claim 21, wherein the first flexure arm is positioned on the opposite side of the sensor module from the second flexure arm.

23. The system according to any one of claims 1 to 22, wherein the base comprises a first flexure arm that is horizontally oriented and coupled to the sensor module.

24. The system according to claim 23, wherein the sensor module comprises a first distal protrusion coupled to the first flexure arm so as to couple the sensor module to the base.

25. The first horizontal locking protrusion is coupled to an end portion of the first flexure arm, and a 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 the distal portion flexes the first flexure arm, allowing the second horizontal locking protrusion to move distally relative to the first horizontal locking protrusion. The system according to claim 24.

26. The system according to claim 24 or 25, wherein the sensor module comprises a second distal protrusion coupled to a second flexure arm of the base.

27. The system according to claim 26, wherein the first distal protrusion is positioned on an opposite side of the sensor module from the second distal protrusion.

28. The sensor module is coupled to the sensor, and the first portion comprises a first flexure arm and a second flexure arm that protrude distally while the first portion is in the proximal starting position and latch-engage over the sensor module to removably secure the sensor module to the first portion. The system according to any one of claims 1 to 27.

29. The system according to claim 28, wherein the sensor module is positioned remotely from the base while the first portion is in the proximal starting position.

30. The system according to claim 29, wherein the sensor module 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 module to the base by moving the first portion distally relative to the second portion.

31. The system according to any one of claims 28 to 30, wherein the system comprises a vertical central axis oriented from the proximal end to the distal end of the system, and the first and second flexure arms of the first portion secure the sensor module to the first portion such that the sensor module is removably coupled to the first portion with a first vertical holding strength.

32. The system according to claim 31, wherein the sensor module comprises a third flexure 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.

33. The system according to claim 32, wherein the second vertical retention strength is greater than the first vertical retention strength such that, when the sensor module is coupled to the base, the first portion is continuously pushed distally to overcome the first and second flexure arms of the first portion and remove the sensor module from the first portion.

34. The system according to claim 32 or 33, wherein the third flexure arm extends from an outer peripheral portion of the sensor module.

35. The system according to any one of claims 1 to 34, wherein the base protrudes from the distal end of the system while the first portion of the nested assembly is positioned at the proximal starting position, and the sensor is configured to couple the sensor to the base by moving the first portion distally relative to the second portion of the system.

36. The system according to claim 35, wherein the base comprises a first radially protruding portion releasably coupled to a second radially protruding portion of the second portion of the nested assembly with a first vertical retention strength.

37. The system according to claim 36, wherein the first radially protruding portion protrudes inwardly and the second radially protruding portion protrudes outwardly.

38. The system according to claim 36 or 37, wherein the system is configured to move the first portion to the distal portion to move the second radially protruding portion relative to the first radially protruding portion and remove the base from the nested assembly.

39. The first part of the nested assembly comprises a first arm that projects distally, the second part of the nested assembly comprises a second flex arm that projects distally, and the system is configured such that moving the first part along the path from the proximal starting position to the distal position causes the first arm to deflect the second flex arm, thereby removing the second flex arm from the base and enabling the base to be decoupled from the nested assembly, according to any one of claims 35 to 38.

40. When the first part is in the proximal starting position, the first arm of the first part is at least partially vertically aligned with the second flex arm of the second part, and as the first part moves to the distal position, the first arm is able to deflect the second flex arm, according to the system of claim 39.

41. When the first part is in the proximal starting position, at least a section of the first arm is positioned directly over the second flex arm, and as the first part moves to the distal position, the first arm is able to deflect the second flex arm, according to the system of claim 39 or 40.

42. The second flex arm comprises a first horizontal projection, and the base comprises a second horizontal projection that is latched to the first horizontal projection to couple the base to the second part of the nested assembly, according to any one of claims 39 to 41.

43. The first arm of the first part deflects the second flex arm of the second part to unlatch the base from the second part of the nested assembly, according to the system of claim 42.

44. The system is configured to couple the sensor to the base at a first position, and to remove the base from the nested assembly at a second position that is distal to the first position, according to any one of claims 39 to 43.

45. The third flexure arm couples the sensor to the base at a first position, removes the second flexure arm from the base at 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 after the sensor is secured to the base, the system of any one of claims 39 - 44.

46. The base projects from a distal end of the system while the first portion of the nested assembly is in the proximal starting position and the sensor is positioned remotely from the base, the system further comprising a spring configured to store a needle, the needle being configured to facilitate insertion of the sensor into the skin, the spring being in a first compressed state when the first portion is in the proximal starting position, the system being configured such that moving the first portion distally from the proximal starting position increases compression of the spring, the first compressed state arranging the first and second portions in a tensioned state, the system of any one of claims 1 - 45.

47. A system for applying a skin - mounted sensor assembly to a recipient's skin, a nested assembly having a first portion configured to move distally relative to a second portion along a path from a proximal starting position to a distal position, a sensor coupled to the first portion, and a latch configurable to prevent the needle from moving proximally relative to the first portion.

48. The first portion is releasably secured to the proximal starting position by a fixing mechanism that prevents the first portion from moving distally relative to the second portion, the system being configured such that moving the first portion distally relative to the second portion before reaching the distal position releases the latch, thereby causing the needle to be stored proximally into the system, the system of claim 47.

49. The fixing mechanism is an interference portion between the first portion and the second portion of the nested assembly, the system of claim 48.

50. The system according to any one of claims 47 to 49, further comprising a first force profile measured along the path, the first force profile having a first magnitude consistent with overcoming the fixing mechanism, a third magnitude consistent with releasing the latch, and a second magnitude consistent with an intermediate portion of the path that is distal to overcoming the fixing mechanism and proximal to releasing the latch.

51. The system according to claim 50, wherein the second magnitude is less than the first and third magnitudes such that the system promotes acceleration of the needle between the intermediate portions of the path to enable an appropriate needle speed when the needle first penetrates the skin.

52. The system according to claim 50 or 51, wherein the first magnitude is at least 100 percent greater than the second magnitude.

53. The system according to any one of claims 50 to 52, wherein the first magnitude is greater than the third magnitude such that the system is configured to prevent the start of the sensor insertion cycle unless the user applies sufficient force to release the latch.

54. The system according to claim 53, wherein the first magnitude is at least 50 percent greater than the third magnitude.

55. The system according to any one of claims 48 to 54, further comprising a second force profile consistent with an intermediate portion of the path that is distal to overcoming the fixing mechanism and proximal to releasing the latch, wherein a proximal millimeter of the second force profile has an average force lower than a distal millimeter of the second force profile in response to the system compressing a spring configured to enable the system to store the needle into the nested assembly.

56. The system according to any one of claims 48 to 55, further comprising a first force profile measured along the path, the first force profile having a first average magnitude that corresponds to moving distally past the proximal half of the fixing mechanism, and a second average magnitude that corresponds to moving distally past the distal half of the fixing mechanism, the first average magnitude being configured to prevent the system from initiating the sensor insertion cycle unless the user applies sufficient force to complete the sensor insertion cycle, and being greater than the second average magnitude.

57. The system according to claim 56, wherein a first force peak corresponding to moving distally past the proximal half of the fixing mechanism is at least 25 percent higher than the second average magnitude.

58. The system according to any one of claims 48 to 57, further comprising a first force profile measured along the path, the first force profile having a first magnitude that corresponds to overcoming the fixing mechanism and a subsequent magnitude that corresponds to terminating the fixing mechanism, the first magnitude comprising a proximal vector and the subsequent magnitude comprising a distal vector.

59. The system according to any one of claims 48 to 58, wherein the fixing mechanism comprises a radially outward protrusion from the first portion, the radially outward protrusion being positioned proximally relative to the proximal end of the second portion while the nested assembly is in the proximal starting position.

60. The system according to claim 59, wherein the radially outward protrusion is configured to deform the second portion into an ellipse to enable the first portion to move distally relative to the second portion.

61. The system according to any one of claims 48 to 60, wherein the fixing mechanism comprises a radially outward protrusion of the first portion that interferes with a radially inward protrusion of the second portion such that the fixing mechanism is configured to deform the second portion into an ellipse to enable the first portion to move distally relative to the second portion.

62. The needle is releasably coupled to the first portion by a needle holder configured to resist distal movement of the first portion relative to the second portion, the fixing mechanism includes a flexible arm of the second portion, and the flexible arm is releasably coupled to the needle holder to releasably fix the first portion to the second portion at the proximal starting position. The system according to any one of claims 48 to 61.

63. The fixing mechanism includes a weak coupling between the first portion and the second portion while the first portion is in the proximal starting position, and the system is configured such that moving the first portion to the distal position breaks the weak coupling. The system according to any one of claims 48 to 62.

64. The fixing mechanism includes a magnet that releasably couples the first portion to the second portion while the first portion is in the proximal starting position. The system according to any one of claims 48 to 63.

65. The system according to any one of claims 47 to 64, further comprising an electric motor for driving the first portion distally relative to the second portion.

66. A skin sensor system configured for transcutaneous monitoring of a recipient, A sensor module housing including a first flex arm, a sensor module housing, A sensor having a first section configured for subcutaneous sensing and a second section mechanically coupled to the sensor module housing, An electrical interconnect coupled to the sensor module housing and the sensor, A base coupled to the first flex arm of the sensor module housing, the base having an adhesive configured to couple the base to the skin of the recipient. A skin sensor system comprising:

67. The system according to claim 66, wherein the electrical interconnect includes a spring.

68. The system according to claim 67, wherein the spring includes a conical portion.

69. The system according to claim 67 or 68, wherein the spring includes a helical portion.

70. The sensor module housing includes at least two proximal protrusions positioned around the outer periphery of the spring, the proximal protrusions being configured to assist in orienting the spring, and a segment of the sensor being positioned between the proximal protrusions, the system according to any one of claims 67 to 69.

71. The system according to claim 70, wherein the sensor module housing is mechanically coupled to the base.

72. The system according to claim 71, wherein the proximal protrusions orient the spring to press the electronic device unit against a first electrical contact of the base and a second electrical contact of the sensor to electrically couple the sensor to the electronic device unit.

73. The system according to any one of claims 66 to 72, wherein the first flexure arm is horizontally oriented and coupled to the base.

74. The system according to claim 73, wherein the first flexure arm extends from an outer peripheral portion of the sensor module housing.

75. The system according to claim 74, wherein the base includes a first proximal protrusion coupled to the first flexure arm to couple the sensor module housing to the base.

76. The system according to any one of claims 66 to 75, wherein the electrical interconnect includes a leaf spring.

77. The system according to any one of claims 66 to 76, wherein 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.

78. The system according to claim 77, wherein the channel positions the first region of the sensor such that a first region is electrically coupled to the electrical interconnect.

79. The system according to claim 78, wherein the leaf spring arcs away from the first region and protrudes proximally to electrically couple to the electronic device unit.

80. The system according to claim 79, wherein at least a portion of the leaf spring forms a "W" shape.

81. The system according to claim 79, wherein at least a portion of the leaf spring forms a "C" shape.

82. The system according to any one of claims 77 to 81, wherein the leaf spring bends around the proximal protrusion, and the leaf spring protrudes proximally and is electrically coupled to the electronic device unit.

83. The system according to any one of claims 66 to 82, further comprising a seal configured to prevent fluid from entering the leaf spring.

84. The system according to claim 83, wherein the sensor module housing is mechanically coupled to a base having an adhesive configured to couple the base to the skin of the recipient.

85. The system according to any one of claims 82 to 84, wherein the leaf spring is oriented to couple the electronic device unit to the base by pressing the leaf spring against a first electrical contact of the electronic device unit and a second electrical contact of the sensor, thereby electrically coupling the sensor to the electronic device unit.

86. The system according to claim 85, wherein a proximal height of the seal is higher than a proximal height of the leaf spring such that the seal contacts the electronic device unit before the electronic device unit contacts the leaf spring.

87. The system according to any one of claims 84 to 86, wherein the sensor module housing comprises a first flexure arm that is horizontally oriented and coupled to the base.

88. The system according to claim 87, wherein the first flexure arm extends from an outer peripheral portion of the sensor module housing.

89. The system according to claim 88, wherein the base comprises a first proximal protrusion coupled to the first flexure arm to couple the sensor module housing to the base.

90. The system according to any one of claims 76 to 98, wherein the sensor module housing comprises a channel in which at least a portion of the second section of the sensor is positioned.

91. The system according to claim 90, wherein a distal portion of the leaf spring is positioned within the channel such that a proximal portion of the leaf spring protrudes proximally from the channel.

92. The system according to claim 91, wherein the sensor module housing comprises a groove that intersects the channel, and the leaf spring comprises a tab positioned within the groove to prevent rotation of the leaf spring.

93. The system according to claim 92, wherein at least a portion of the leaf spring forms a "C" shape.

94. The system according to claim 92 or 93, wherein the sensor module housing is mechanically coupled to a base having an adhesive configured to couple the base to the skin of the recipient.

95. The system according to claim 94, wherein the sensor module housing comprises a first flexure arm that is horizontally oriented and coupled to the base.

96. The system according to claim 95, wherein the first flexure arm extends from an outer peripheral portion of the sensor module housing.

97. The system according to claim 96, wherein the base comprises a first proximal protrusion coupled to the first flexure arm to couple the sensor module housing to the base.

98. The system according to any one of claims 66 to 97, wherein the electrical interconnection has a resistance of less than 100 ohms.

99. The system according to any one of claims 66 to 98, wherein the electrical interconnection has a resistance of less than 5 ohms.

100. The system according to any one of claims 66 to 99, wherein the electrical interconnection has a compressive force of less than 1 pound over an active compression range.

101. The system according to any one of claims 66 to 100, wherein the electrical interconnection has a compressive force of less than 1 pound, and the compressive force is the force required to compress the spring from its relaxed position by 30 percent.

102. The system according to any one of claims 66 to 101, wherein the spring is configured such that compressing the spring from its relaxed position by 25 percent requires a force of at least 0.05 pound and less than 0.5 pound, and moving an end of the spring requires a movement of at least 0.1 millimeter and less than 1.1 millimeters.

103. A system for applying a skin-mounted sensor assembly to the skin of a recipient, comprising: A nested assembly having a first portion configured to move distally relative to a second portion along a path from a proximal starting position to a distal position; A sensor coupled to the first portion; A base comprising an adhesive configured to couple the sensor to the skin.

104. The system according to claim 103, wherein the nested assembly further comprises a third portion configured to move distally relative to the second portion.

105. The system according to claim 104, further comprising a first spring 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.

106. The system according to claim 105, wherein at the proximal starting position of the nested assembly, the first portion is locked to the second portion.

107. The system according to claim 106, wherein the system is configured such that moving the third portion distally relative to the second portion unlocks the first portion from the second portion.

108. The system according to claim 106 or 107, wherein a first proximal protrusion having a first hook passes through a first hole in the second portion to lock the first portion to the second portion.

109. The system according to claim 108, wherein the third portion includes a first distal protrusion, and the system is configured such that moving the third portion distally relative to the second portion engages a lamp portion to bend the first proximal protrusion and unlock the first portion from the second portion.

110. The system according to any one of claims 104 to 109, wherein the sensor is positioned within the second portion while the base protrudes from the distal end of the system such that the system moves the first portion distally relative to the second portion to couple the sensor to the base.

111. The system according to any one of claims 104 to 109, further comprising a sensor module coupled to a distal portion of the first portion such that moving the first portion to the distal position couples the sensor module to the base.

112. The system according to claim 111, wherein the sensor is coupled to the sensor module while the first portion is positioned at the proximal starting position.

113. The system according to any one of claims 104 to 112, wherein 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.

114. The system according to claim 113, comprising a first protrusion that engages with at least one hole of the second part and the third part to lock the third part to the second part.

115. The system according to claim 113 or 114, comprising a second protrusion that engages with at least one hole of the first part and the second part to lock the first part to the second part in response to the first part moving distally relative to the second part.

116. The system according to any one of claims 104 to 115, further comprising a first spring positioned between the third part and the second part such that moving the third part distally relative to the second part compresses the first spring and unlocks the first part from the second part, and the compressed first spring enables the first part to be pushed distally relative to the second part, pushing at least a portion of the sensor out of the distal end of the system and triggering a needle storage mechanism to enable a second spring to store the needle.

117. A sensor inserter assembly for applying a skin-on assembly to a recipient's skin, the sensor inserter assembly comprising a needle assembly, a sensor module, a base, an actuating member, and a storage member, the sensor inserter assembly having an initial configuration in which at least the sensor module is disposed in a proximal starting position, and the sensor inserter assembly further having a deployed configuration in which at least the sensor module and the base are disposed in a distal application position, the actuating member being configured to move the needle assembly from the proximal starting position to a distal insertion position when actuated, the storage member being configured to move the needle assembly from the distal insertion position to a proximal storage position when actuated.

118. The sensor inserter assembly according to claim 117, wherein the sensor module comprises one sensor and a plurality of electrical contacts.

119. The sensor inserter assembly according to claim 118, wherein in the initial configuration, the sensor is electrically coupled to at least one of the electrical contacts.

120. The sensor insertion machine assembly according to any one of claims 117 to 119, wherein in the initial configuration, the actuating member is in a non - energy - applied state.

121. The sensor insertion machine assembly according to any one of claims 117 to 119, wherein the actuating member is configured to be energized by a user before being activated.

122. The sensor insertion machine assembly according to any one of claims 117 to 119 or 121, wherein in the initial configuration, the actuating member is in an energy - applied state.

123. The sensor insertion machine assembly according to any one of claims 117 to 122, wherein the actuating member comprises a spring.

124. The sensor insertion machine assembly according to any one of claims 117 to 123, wherein in the initial configuration, the spring is in a non - stressed state.

125. The sensor insertion machine assembly according to any one of claims 117 to 123, wherein in the initial configuration, the spring is in a compressed state.

126. The sensor insertion machine assembly according to any one of claims 117 to 125, further comprising a first part and a second part, wherein the first part is fixed to the second part at least axially when the sensor insertion machine assembly is in the initial configuration, and the first part is movable relative to the second part at least distally after activation of the actuating member.

127. The sensor insertion machine assembly according to claim 126, wherein the first part is operably coupled to the needle assembly to fix the needle assembly in the proximal starting position before activation of the actuating member and to bias the needle assembly towards the distal insertion position after activation of the actuating member.

128. The sensor insertion machine assembly according to any one of claims 117 to 126, wherein in the initial configuration, the storage member is in a non - energy - applied state.

129. The sensor insertion machine assembly according to any one of claims 117 to 128, wherein the storage member is configured to be energized by the movement of the needle assembly from the proximal starting position to the distal insertion position.

130. The sensor insertion machine assembly according to any one of claims 117 to 127 or 129, wherein in the initial configuration, the storage member is in an energy - applied state.

131. The sensor insertion machine assembly according to any one of claims 117 to 131, wherein the storage member includes a spring. **Claim 132** The sensor insertion machine assembly according to claim 131, wherein the spring is integrally formed with the needle assembly. **Claim 133** The sensor insertion machine assembly according to claim 131 or 132, wherein the spring is operably coupled to the needle assembly. **Claim 134** The sensor insertion machine assembly according to any one of claims 131 to 133, wherein in the initial configuration, the spring is in a non-stressed state. **Claim 135** The sensor insertion machine assembly according to any one of claims 131 to 133, wherein in the initial configuration, the spring is in a compressed state. **Claim 136** The sensor insertion machine assembly according to any one of claims 131 to 135, wherein in the second configuration, the spring is in a compressed state. **Claim 137** The sensor insertion machine assembly according to any one of claims 131 to 135, wherein in the second configuration, the spring is in a tension-applied state. **Claim 138** The sensor insertion machine assembly according to any one of claims 117 to 137, wherein the sensor insertion machine assembly further includes a third portion, and the third portion is operably coupled to the first portion. **Claim 139** The sensor insertion machine assembly according to claim 138, wherein the actuating member is integrally formed with the third portion. **Claim 140** The sensor insertion machine assembly according to claim 138 or 139, wherein the actuating member is operably coupled to the third portion. **Claim 141** The sensor insertion machine assembly according to any one of claims 117 to 140, further comprising the engagement structure configured to prevent movement of the first portion in the distal direction relative to the second portion until the engagement structure is disengaged. **Claim 142** The sensor insertion machine assembly according to claim 141, wherein disengaging the engagement structure activates the actuating member. **Claim 143** The sensor insertion machine assembly according to claim 141 or 142, wherein the engagement structure includes a proximal extending tab of the first portion and a socket of the second portion configured to receive the proximal extending tab. **Claim 144** The sensor insertion machine assembly according to any one of claims 117 to 143, comprising a decoupling member configured to decouple the engagement structure.

145. The sensor insertion machine assembly according to claim 144, wherein the decoupling member comprises a distal extending tab of the third portion.

146. The sensor insertion machine assembly according to any one of claims 138 to 145, comprising an engagement structure configured to prevent proximal movement of the third portion relative to the first portion.

147. The sensor insertion machine assembly according to claim 146, wherein the engagement structure comprises a distal extending latch of the third portion and a ledge of the first portion configured to engage the distal extending latch.

148. The sensor insertion machine assembly according to claim 146 or 147, comprising an engagement structure configured to prevent proximal movement of the needle assembly at least when the needle assembly is in the distal insertion position.

149. The sensor insertion machine assembly according to any one of claims 146 to 148, wherein the engagement structure comprises a radially extending release feature of the needle assembly and an inner surface of the first portion configured to compress the release feature.

150. The sensor insertion machine assembly according to any one of claims 146 to 149, comprising a decoupling member configured to decouple the engagement structure of the first portion and the needle assembly.

151. The sensor insertion machine assembly according to claim 150, wherein the decoupling member comprises an inner surface of the second portion configured to further compress the release feature.

152. The sensor insertion machine assembly according to any one of claims 117 to 151, further comprising a trigger member configured to activate the actuating member.

153. The sensor insertion machine assembly according to claim 152, wherein the trigger member is operably coupled to the third portion.

154. The sensor insertion machine assembly according to claim 152 or 153, wherein the trigger member is integrally formed with the third portion.

155. The sensor insertion machine assembly according to any one of claims 152 to 154, wherein the trigger member includes a proximally extending button.

156. The sensor insertion machine assembly according to any one of claims 152 to 154, wherein the trigger member includes a radially extending button.

157. The sensor insertion machine assembly according to any one of claims 152 to 156, wherein the trigger member is configured to disengage the engagement structure between the first portion and the third portion.

158. The sensor insertion machine assembly according to any one of claims 117 to 157, further comprising a releasable locking member configured to prevent activation of the actuating member until the locking member is released.

159. The sensor insertion machine assembly according to claim 158, wherein the releasable locking member is configured to prevent proximal movement of the third portion relative to the first portion until the locking member is released.

160. The sensor insertion machine assembly according to claim 158 or 159, wherein the releasable locking member includes a proximally extending tab of the first portion and a latch feature of the third portion configured to receive the proximally extending tab.

161. The sensor insertion machine assembly according to any one of claims 158 to 160, wherein the releasable locking member is configured to prevent energization of the sensor insertion machine assembly.

162. The sensor insertion machine assembly according to any one of claims 158 to 161, wherein the releasable locking member is configured to prevent energization of the actuating member.

163. A sensor insertion machine assembly for applying a component on the skin to a recipient's skin, comprising: A component on the skin movable distally from at least a proximal position to a distal position; A first fixing feature configured to removably fix the component on the skin to the proximal position; A second fixing feature configured to fix the component on the skin to the distal position; A first resistance feature configured to prevent proximal movement of the component on the skin when at least the component on the skin is in the distal position.

164. The sensor insertion machine assembly according to claim 163, wherein the first resistance feature is configured to prevent proximal movement of the skin component when the skin component is fixed at the distal position. **Claim 165** The sensor insertion machine assembly according to claim 163 or 164, wherein the first fixing feature is configured to removably fix the skin component to the needle assembly. **Claim 166** The sensor insertion machine assembly according to claim 164 or 165, wherein the skin component comprises a sensor module. **Claim 167** The sensor insertion machine assembly according to claim 166, wherein the sensor module comprises one sensor and a plurality of electrical contacts. **Claim 168** The sensor insertion machine assembly according to claim 167, wherein the sensor is electrically coupled to at least one of the electrical contacts, at least when the sensor insertion machine assembly is in the first configuration. **Claim 169** The sensor insertion machine assembly according to any one of claims 163 to 168, wherein the skin component comprises a base. **Claim 170** The sensor insertion machine assembly according to any one of claims 163 to 169, wherein the skin component comprises a transmitter. **Claim 171** The sensor insertion machine assembly according to any one of claims 163 to 170, wherein the second fixing feature is configured to fix the skin component to a second skin component. **Claim 172** The sensor insertion machine assembly according to any one of claims 163 to 171, wherein the sensor insertion machine assembly comprises at least one distally extending leg, and the first fixing feature comprises an adhesive disposed on a surface facing distally of the leg. **Claim 173** The sensor insertion machine assembly according to any one of claims 163 to 171, wherein the sensor insertion machine assembly comprises at least one distally extending member, and the first fixing feature comprises a surface of the distally extending member configured to engage in frictional engagement with a corresponding structure of the skin component. **Claim 174** The sensor insertion machine assembly according to claim 173, wherein the corresponding structure of the skin component comprises an elastomeric member. **Claim 175** The sensor insertion machine assembly according to claim 173 or 174, wherein the distally extending member comprises at least one leg of the sensor insertion machine assembly. **Claim 176** The sensor insertion machine assembly according to any one of claims 173 to 175, wherein the distal extension member comprises a needle.

177. The sensor insertion machine assembly according to any one of claims 163 to 174, wherein the second fixing feature comprises an adhesive disposed on a surface facing distal to the skin component.

178. The sensor insertion machine assembly according to any one of claims 163 to 177, wherein the second fixing feature comprises an elastomeric member configured to receive the skin component.

179. The sensor insertion machine assembly according to any one of claims 163 to 178, wherein the first resistance feature comprises a surface facing distal to the sensor insertion machine assembly.

180. The sensor insertion machine assembly according to any one of claims 163 to 179, wherein the first resistance feature is distal to an adhesive disposed on a surface facing distal to the skin component.

181. The sensor insertion machine assembly according to any one of claims 163 to 180, further comprising a pusher configured to move the skin component from the proximal position to the distal position.

182. The sensor insertion machine assembly according to any one of claims 163 to 181, further comprising a release feature configured to release the pusher from the skin component after at least the skin component reaches the distal position.

183. The sensor insertion machine assembly according to claim 182, wherein the release feature comprises a weakened portion of the pusher.

184. The sensor insertion machine assembly according to claim 182 or 183, wherein the release feature comprises a weakened portion of the skin component.

185. The sensor insertion machine assembly according to any one of claims 163 to 184, further comprising a sensor assembly configured to be coupled to the skin component, wherein a third fixing feature is configured to removably fix the sensor assembly in a proximal position, and a fourth fixing feature is configured to fix the sensor assembly to the skin component.

186. A system for applying a skin sensor assembly to a recipient's skin, comprising: A nested assembly having a first portion configured to move distally relative to a second portion along a path from a proximal starting position to a distal position. A sensor module coupled to the first portion, the sensor module including a sensor module housing, the sensor module housing including a first flexure arm, the sensor module; A base coupled to the second portion so as to protrude from the distal end of the system, the base comprising an adhesive configured to couple the sensor module to the skin, moving the first portion to the distal position causing the sensor module to be coupled to the base, the base; A system comprising.

187. A device substantially shown and / or described in the specification and / or drawings.

188. A method substantially shown and / or described in the specification and / or drawings.

189. A system substantially shown and / or described in the specification and / or drawings.

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