Apparatus, System, and Method for Controlling Sensor Deployment

Abstract

This example generally relates to an apparatus, system, and method for deploying a medical device onto a recipient's skin. The medical device can include a transcutaneous analyte sensor that is applied to the recipient's skin. The apparatus, system, and method can be for reducing friction between the sensor and an insertion element and / or for controlling sensor deployment.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 351,297, filed on June 10, 2022, the entire content of which is incorporated herein by reference.

[0002] Medical device systems and methods. More specifically, devices, systems, and methods are provided for controlling the deployment of a transcutaneous analyte sensor to a recipient's skin.

Background Art

[0003] Diabetes mellitus is a disorder in which the pancreas cannot produce sufficient insulin (type 1 or insulin - dependent) and / or insulin is ineffective (type 2 or non - insulin - dependent). In a diabetic state, the victim is troubled by hyperglycemia, which can cause many physiological disorders associated with the deterioration of small blood vessels, such as kidney failure, skin ulcers, or bleeding into the vitreous of the eye. Hypoglycemic reactions (hypoglycemia) can be induced by inadvertent over - administration of insulin or after normal administration of insulin or glucose - lowering agents accompanied by abnormal exercise or insufficient food intake.

[0004] Conventionally, people with diabetes carry self - monitoring blood glucose (SMBG) monitors, which typically require an unpleasant finger - pricking method. Due to lack of comfort and convenience, people with diabetes usually measure their glucose levels only 2 - 4 times a day. Unfortunately, such time intervals are too widely spaced and dispersed, so people with diabetes may be too late to know about hyperglycemic or hypoglycemic states, sometimes leading to dangerous side effects. Glucose levels can alternatively be continuously monitored by a measurement system including a sensor assembly on the skin. The sensor assembly may have a wireless transmitter that sends measurement data to a receiver, and the receiver can process and display information based on the measurements.

[0005] The process of applying the sensor to a person is important for such a system to be effective and user-friendly. The application process should result in a skin-mounted sensor assembly that can be attached to a person in a state where the sensor assembly on the skin can detect analyte (e.g., glucose) level information, communicate the detected data to a transmitter, and transmit the analyte level information to a receiver.

[0006] Exemplary systems are disclosed in Patent Document 1, Patent Document 2, and Patent Document 3, which are owned by the assignee of the present application and are hereby incorporated by reference in their entirety.

[0007] This "Background Art" is provided to introduce a brief background of the "Summary of the Invention" and "Detailed Description of the Invention" that follow. This "Background Art" is not intended to assist in determining the scope of the claimed subject matter, nor is it to be construed as limiting the claimed subject matter to implementations that solve any or all of the disadvantages or problems presented above.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0009] The present system and method relate to an apparatus, system, and method for a medical device. More specifically, an apparatus, system, and method for deploying a transcutaneous analyte sensor onto a recipient's skin are provided. The apparatus, system, and method can be for reducing friction between a sensor and an insertion element and / or for controlling sensor deployment. Various embodiments of the present system, device, and method can have several features, none of which alone is responsible for its desirable attributes. Without limiting the scope of the present embodiments as represented by the following claims, some of their more prominent features are briefly considered herein. After considering this discussion, and specifically after reading the section entitled "DETAILED DESCRIPTION OF THE INVENTION," one will understand how the features of the present embodiments provide the advantages described herein.

[0010] In a first aspect, a medical device system comprises a housing configured to be worn on a recipient's skin and including a distal surface facing toward the skin and a proximal surface facing opposite the distal surface, the housing including an opening for retracting an insertion element proximally therethrough; an analyte sensor having a first portion coupled to the housing and a second portion extending distally from the housing and configured to be guided into the recipient's skin by the insertion element; and a stopper body configured to prevent the analyte sensor from retracting proximally through the opening when the insertion element retracts proximally through the opening.

[0011] The implementation of the embodiment may include one or more of the following. The analyte sensor may include a bend positioned between a first portion and a second portion, and the bend may be axially aligned with the opening. The second portion may be linear and axially aligned with the opening. The stopper body may be configured to contact the analyte sensor to prevent the analyte sensor from retracting proximally when the insertion element retracts proximally through the opening. The stopper body may be positioned proximate to the opening. The stopper body may include a tab extending into the opening. The first portion of the analyte sensor may be positioned within a cavity, and the tab may extend from the cavity into the opening. The stopper body may be integrated with the housing. The stopper body may include a plug positioned within the opening. The plug may include a gasket. The plug may have a chamfer. The plug may be pierceable by the insertion element. The stopper body may be positioned proximally to the analyte sensor. The system may further include an insertion element that includes a channel for receiving the analyte sensor. The insertion element may include a needle. The needle hub may be positioned at the proximal portion of the needle, and the stopper body may be positioned between the needle hub and the analyte sensor. The insertion element may be positioned within the opening of the housing and extend parallel to the second portion of the analyte sensor. The stopper body may surround the insertion element. The stopper body may contact the insertion element. The analyte sensor may include a transcutaneous analyte sensor.

[0012] In a second aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, an elongate analyte sensor coupled to the housing and extending distally from the housing and configured to be positioned within the recipient's skin, and an elongate insertion element including a shaft configured to extend along a portion of the elongate analyte sensor and to guide the elongate analyte sensor into the recipient's skin, and a spacer body positioned between a portion of the elongate analyte sensor and the shaft and configured to space a portion of the elongate analyte sensor from the shaft.

[0013] Implementation of the embodiment may include one or more of the following. The spacer body may be removable from between a portion of the elongated analyte sensor and the shaft. The spacer body may be manually removable from between a portion of the elongated analyte sensor and the shaft. The system may further include a tether coupled to the spacer body and configured to be pulled to remove the spacer body from between a portion of the elongated analyte sensor and the shaft. The tether and the spacer body may be formed from a single piece of material. The tether may include a pull tab for the user to pull. The spacer body may include a sheath surrounding the elongated insertion element. The sheath may include a channel in which the elongated analyte sensor is positioned. The cover may cover the distal surface of the housing and be coupled to the spacer body. The system may further include an applicator housing configured to hold the housing and including a proximal end and a distal opening for deploying the housing onto the skin from the middle, and the cover may include a cap positioned at the distal opening. The system may further include a tether coupled to the spacer body and coupled to the cap. Removal of the cap may pull a tether coupled to the spacer body to remove the spacer body from between a portion of the elongated analyte sensor and the shaft. The system may further include an adhesive patch positioned on the distal surface of the housing, and the cover may include a liner cover for the adhesive patch. The spacer body may include a shape memory alloy. The elongated insertion element may have a first coefficient of thermal expansion, and the spacer body may have a second coefficient of thermal expansion different from the first coefficient of thermal expansion. The spacer body may be compressible. The elongated insertion element may include a channel for receiving a portion of the elongated analyte sensor. The spacer body may be removable and configured to be removed to seat a portion of the elongated analyte sensor within the channel. The elongated insertion element may include a needle. The system may further include a needle hub positioned on the proximal portion of the needle, and the spacer body may be positioned on the needle hub.

[0014] In a third aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, an elongated analyte sensor coupled to the housing and extending distally therefrom and configured to be positioned within the recipient's skin, and an elongated insertion element including a shaft extending along a portion of the elongated analyte sensor and configured to be inserted into the skin to guide the elongated analyte sensor into the recipient's skin and to be retracted from the skin, and a displacement mechanism configured to displace a portion of the elongated analyte sensor relative to the elongated insertion element prior to retracting the shaft from the skin to reduce static friction between the elongated analyte sensor and the shaft.

[0015] The implementation of the embodiment may include one or more of the following. The displacement mechanism may be configured to slide a portion of the elongated analyte sensor relative to the shaft before retracting the shaft from the skin in order to reduce the static friction between the elongated analyte sensor and the shaft. The system may further include a hub positioned at the proximal portion of the elongated insertion element, and the displacement mechanism may include a compressible body positioned between the hub and the proximal surface of the housing. The displacement mechanism may include a compressible body that protrudes distally from the distal surface of the housing. The displacement mechanism may be configured to vibrate one or more of the elongated insertion element or a portion of the elongated analyte sensor before retracting the shaft from the skin in order to reduce the static friction between the elongated analyte sensor and the shaft. The system may further include an insertion assembly for inserting the shaft of the elongated insertion element into the skin, and the insertion assembly may include the displacement mechanism. The displacement mechanism may include a cover that covers the distal surface of the housing. The system may further include an applicator housing configured to hold the housing and including a proximal end and a distal opening for deploying the housing onto the skin, and the cover may include a cap positioned at the distal opening. The cap may include a cam surface for applying a force to the housing to displace a portion of the elongated analyte sensor relative to the elongated insertion element. The system may further include an adhesive patch positioned on the distal surface of the housing, and the cover may include a liner cover for the adhesive patch.

[0016] In a fourth aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, an elongated analyte sensor coupled to the housing and extending distally therefrom and configured to be positioned within the recipient's skin, and an elongated insertion element including a shaft extending along a portion of the elongated analyte sensor and configured to be inserted into the skin to guide the elongated analyte sensor into the recipient's skin, the shaft including a surface configured to reduce friction with a portion of the elongated analyte sensor.

[0017] Implementations of the embodiments may include one or more of the following. The surface may be configured to reduce the static friction with a portion of the elongated analyte sensor. The surface may include a surface texture. The surface may include a surface roughness of 35 root mean square (RMS) microinches or greater. The surface may include one or more of ridges, holes, or grooves. The surface may include a coating configured to reduce the friction with a portion of the elongated analyte sensor. The coating may include a lubricant. The coating may include one or more of a spray coating, a brush coating, an electrostatic coating, or more preferably plating, a dip coating, or vapor deposition. The coating may include a polymer. The coating may include a thermal oxide. The coating may include an inert material. The coating may be coupled to the shaft. The coating may have a thickness of less than 1.5 micrometers on the shaft. The coating may be cured, i.e., cured via addition curing, condensation curing, thermal curing, etc. The coating may include silicone. The silicone may include an amino-functional dimethylsiloxane copolymer. The surface may be configured to reduce the hydrogen bonding with a portion of the elongated analyte sensor. The elongated insertion element may include a needle. The elongated insertion element may include a channel for receiving a portion of the elongated analyte sensor. The channel may have a C-shaped cross-section.

[0018] In a fifth aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, an elongated analyte sensor coupled to the housing and extending distally from the housing and configured to be positioned within the recipient's skin, and an elongated insertion element, the elongated insertion element including a shaft extending along a portion of the elongated analyte sensor and configured to be inserted into the skin to guide the elongated analyte sensor into the recipient's skin, the shaft having a V-shaped or W-shaped cross-sectional channel for receiving a portion of the elongated analyte sensor.

[0019] Implementations of the embodiments may include one or more of the following. The V-shaped cross-section channel may have an angle of 60 degrees to 120 degrees. The V-shaped cross-section channel may have an angle of 90 degrees. The W-shaped cross-section channel may be formed by an elongated protrusion added to the central portion of the elongated insertion element having a C-shaped cross-section. The outer surface of the elongated analyte sensor may have a circular cross-section.

[0020] In a sixth aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, and an elongated insertion element including a shaft configured to be inserted into the skin, and an elongated analyte sensor coupled to the housing, extending along the elongated insertion element, and configured to be guided into the skin by the elongated insertion element, wherein the elongated analyte sensor includes a surface configured to reduce friction with the elongated insertion element.

[0021] Implementations of the embodiments may include one or more of the following. The surface may be configured to reduce static friction with the elongated analyte sensor. The surface may be configured to reduce hydrogen bonding with the elongated insertion element. The elongated insertion element may include a needle. The elongated insertion element may include a channel for receiving a portion of the elongated analyte sensor.

[0022] In a seventh aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, and an elongated insertion element including a shaft configured to be inserted into the skin, and an elongated analyte sensor coupled to the housing, extending along the elongated insertion element, and configured to be guided into the skin by the elongated insertion element, wherein the elongated analyte sensor has an elliptical cross-section.

[0023] The implementation of the embodiment may include one or more of the following. The outer surface of the elongated analyte sensor may be configured to reduce the static friction with the elongated insertion element. The elongated insertion element may include a needle. The elongated insertion element may include a channel for receiving a portion of the elongated analyte sensor. The channel may have a C-shaped cross-section.

[0024] In an eighth aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, and an analyte sensor having a first portion coupled to the housing and a second portion extending distally from the housing and configured to be inserted into the recipient's skin, the analyte sensor including a bend having at least two kinks that angle the first portion relative to the second portion.

[0025] The implementation of the embodiment may include one or more of the following. The second portion may extend perpendicularly from the distal surface of the housing. The first portion may extend parallel to the distal surface of the housing. The at least two kinks may bend the second portion to be perpendicular to the first portion. The at least two kinks may include a first kink and a second kink, the first kink having an angle less than 90 degrees and the second kink having an angle less than 90 degrees.

[0026] In a ninth aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, an analyte sensor coupled to the housing and extending distally from the housing and configured to be positioned within the recipient's skin, an insertion element extending along the analyte sensor and configured to guide the analyte sensor into the recipient's skin, an insertion assembly configured to drive the insertion element into the recipient's skin, and a force channeling component configured to direct force from the insertion assembly in proximity to the insertion element.

[0027] Implementations of the embodiments may include one or more of the following. The insertion assembly may include a plate configured to be positioned proximal to the proximal surface. The force channeling component may include one or more protrusions on a plate configured to direct force proximal to the insertion element. The one or more protrusions may be configured to apply force to the proximal surface of the housing proximate to the insertion element. The housing may include an opening for retracting the insertion element proximally through the skin, and the force channeling component is configured to contact the proximal surface of the housing proximate to the opening. The insertion element may include a needle.

[0028] In a tenth aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, and an elongated analyte sensor coupled to the housing and extending distally from the housing and configured to be positioned within the recipient's skin and having a flexural modulus greater than 8 gigapascals, and an elongated insertion element, the elongated insertion element including a shaft configured to extend along a portion of the elongated analyte sensor and to be inserted into the skin to guide a portion of the elongated analyte sensor into the recipient's skin.

[0029] Implementations of the embodiments may include one or more of the following. The flexural modulus may be greater than 8.4 gigapascals. The elongated analyte sensor may include a first portion coupled to the housing and a second portion extending distally from the distal surface of the housing, the second portion having a flexural modulus greater than 8 gigapascals. The shaft may include a channel configured to receive a portion of the elongated analyte sensor. The elongated insertion element may include a needle.

[0030] In an eleventh aspect, a medical device system is configured to be worn on a recipient's skin and includes a housing having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, an elongated analyte sensor coupled to the housing and extending distally from the housing and configured to be positioned within the recipient's skin, and an elongated insertion element. The elongated insertion element includes a shaft having a channel in which a portion of the elongated analyte sensor is positioned. The shaft is configured to be inserted into the skin to guide a portion of the elongated analyte sensor into the skin, and the shaft has a diametrical clearance of at least 0.07 millimeters from a portion of the elongated analyte sensor.

[0031] Implementations of the embodiments may include one or more of the following. The diametrical clearance may be at least 0.10 millimeters. The elongated insertion element may include a needle. The channel may have a C-shaped cross-section. The elongated analyte sensor may have a first portion coupled to the housing and a second portion extending distally from the distal surface of the housing and positioned within the channel.

[0032] In a twelfth aspect, a medical device system includes a housing configured to be worn on a recipient's skin and having a distal surface configured to face the skin and a proximal surface facing opposite the distal surface, an elongated analyte sensor having a first portion coupled to the housing and a second portion extending distally from the housing and configured to be positioned within the recipient's skin, the second portion having a diameter, an elongated insertion element. The elongated insertion element includes a shaft having an opening for a channel in which the second portion of the elongated analyte sensor is positioned. The shaft is configured to be inserted into the skin to guide the second portion into the skin, and the channel of the opening has a width, and a ratio of the diameter to the width is less than 0.9.

[0033] Implementation of the embodiment may include one or more of the following. The ratio of the diameter to the width may be less than 0.8. The ratio of the diameter to the width may be less than 0.7. The channel may have a C-shaped cross section. The elongated insertion element may include a needle.

[0034] In a thirteenth aspect, the method is to reduce the friction between the analyte sensor and the insertion element during or subsequent to a sterilization process performed on the analyte sensor and the insertion element and before retracting the insertion element from the skin of the recipient, the insertion element being configured to guide the analyte sensor into the skin of the recipient and retract from the skin of the recipient, reducing the friction.

[0035] Implementations of the embodiments may include one or more of the following. The method may further include vibrating the analyte sensor and the insertion element to reduce friction between the analyte sensor and the insertion element. The method may further include raising the ambient temperature or lowering the ambient temperature to reduce friction between the analyte sensor and the insertion element. The method may further include lowering the ambient humidity to reduce friction between the analyte sensor and the insertion element. The method may further include packaging the analyte sensor and the insertion element with a desiccant. The friction may include static friction. The insertion element may include an elongate insertion element including a shaft configured to be inserted into the skin, and the analyte sensor may comprise an elongate analyte sensor having a portion extending along the shaft of the elongate insertion element. The shaft may include a channel, and a portion of the elongate analyte sensor may be positioned within the channel. The method may further include reducing hydrogen bonding between the analyte sensor and the insertion element. The insertion element may include a needle. The analyte sensor may be coupled to a housing configured to be worn on the recipient's skin, the housing including an opening through which the insertion element passes. The analyte sensor may include a first portion coupled to the housing and a second portion extending distally from a distal surface of the housing. The housing, the analyte sensor, and the insertion element may be positioned within an applicator housing. The sterilization process may include applying a sterilizing gas to the analyte sensor and the insertion element. The sterilization process may include an ethylene oxide sterilization process.

[0036] In a fourteenth aspect, the method is coating at least a portion of the shaft of the elongate insertion element with a material, the elongate insertion element being for guiding an elongate analyte sensor into the recipient's skin with the elongate analyte sensor extending along a portion of the shaft when inserted into the skin, the material being configured to reduce friction between the elongate insertion element and the elongate analyte sensor, the coating.

[0037] Implementations of the embodiments may include one or more of the following. The method may further include positioning an elongate insertion element adjacent to an elongate analyte sensor. The method may further include positioning the elongate analyte sensor within a channel of the elongate insertion element. The elongate analyte sensor may extend distally from a housing configured to be worn on a recipient's skin. The material may be configured to reduce static friction with the elongate analyte sensor. The coating may include one or more of plating, dip coating, or vapor deposition. The coating may be coupled to the shaft. The coating may have a thickness of less than 1.5 micrometers on the shaft. The method may further include curing the coating on the shaft. The coating may include silicone. The silicone may include an amino-functionalized dimethylsiloxane copolymer. The method may further include positioning the shaft within a solution of the material. The solution may include a solvent. The material may produce a coefficient of friction of a portion of the shaft that is less than one tenth of the coefficient of friction of a surface of a portion of the shaft coated with the material. The elongate insertion element may include a needle.

[0038] In a fifteenth aspect, a medical device system includes a housing configured to be worn on a recipient's skin and including a distal surface facing the skin and a proximal surface facing opposite the distal surface, an elongate analyte sensor coupled to the housing and extending distally from the housing and configured to be positioned within the recipient's skin, and one or more elongate insertion elements including a shaft configured to extend along a portion of the elongate analyte sensor, the one or more elongate insertion elements being configured to guide the elongate analyte sensor into the recipient's skin with the elongate analyte sensor positioned external to the shaft of each elongate insertion element.

[0039] The implementation of the embodiment may include one or more of the following. The elongated analyte sensor may include a central axis, and each of the one or more elongated insertion elements may include its respective central axis, and the central axis of the elongated analyte sensor is parallel to and laterally spaced from each of the respective central axes of the one or more elongated insertion elements. At least a portion of each of the one or more elongated insertion elements may include a convex outer surface configured to extend parallel to and adjacent to the outer surface of the elongated analyte sensor. Each of the one or more elongated insertion elements may include an outer surface having a longitudinally extending segment configured to extend parallel to and adjacent to the outer surface of the elongated analyte sensor. Each of the one or more elongated insertion elements may lack a channel for holding the elongated analyte sensor. Each of the one or more elongated insertion elements may include an outer surface configured to contact the outer surface of the elongated analyte sensor in a deployed configuration. The one or more elongated insertion elements may include at least two of the elongated insertion elements. Each of the at least two elongated insertion elements may include an outer surface configured to contact the outer surface of the elongated analyte sensor in a deployed configuration. The at least two elongated insertion elements may be configured to be positioned on both sides of the elongated analyte sensor in a deployed configuration. The elongated analyte sensor may be configured to be positioned between the at least two elongated insertion elements in a deployed configuration. Each of the at least two elongated insertion elements may include a proximal end portion and a distal tip, and further include a needle hub coupled to the respective proximal end portion of the at least two elongated insertion elements. The shaft of each of the at least two elongated insertion elements may extend from the proximal end portion to the respective distal tip, and the distal tips of the at least two elongated insertion elements are not connected to each other. The at least two elongated insertion elements may include a first elongated insertion element and a second elongated insertion element, the first elongated insertion element having a first outer surface, and the second elongated insertion element having a second outer surface that extends parallel to and is laterally spaced from the first outer surface. The at least two elongated insertion elements may include a first elongated insertion element and a second elongated insertion element, the first elongated insertion element having a first outer surface, and the second elongated insertion element having a second outer surface that extends parallel to and contacts the first outer surface.The one or more elongate insertion elements may include at least three of the elongate insertion elements. The elongate analyte sensor may be a first elongate analyte sensor, coupled to a housing, extending distally from the housing, and further comprising a second elongate analyte sensor configured to be positioned within the skin of a recipient. Each of the one or more elongate insertion elements includes a shaft configured to extend along a portion of the second elongate analyte sensor. Each of the one or more elongate insertion elements is configured to guide the second elongate analyte sensor into the skin of the recipient with the second elongate analyte sensor positioned outside the shaft of each respective elongate insertion element. At least one of the one or more elongate insertion elements may have an oval cross-section. The elongate analyte sensor may include a distal tip, and the one or more elongate insertion elements include distal tips configured to extend radially over at least a portion of the distal tip of the elongate analyte sensor. The distal tips of the one or more elongate insertion elements may have a diameter greater than the diameter of the shaft of each respective one of the one or more elongate insertion elements. The system may further include a rotation mechanism for rotating the distal tips of the one or more elongate insertion elements to expose a portion of the distal tip of the elongate analyte sensor.

[0040] Any feature of any embodiment of any aspect, including but not limited to any embodiment of the 1st to 15th aspects mentioned above, is applicable to any other aspect and embodiment specified herein, including but not limited to any embodiment of the 1st to 15th aspects mentioned above. Further, any feature of any embodiment of various aspects, including but not limited to any embodiment of the 1st to 15th aspects mentioned above, can be combined, independently, in part or in whole, in any manner with other embodiments described herein. For example, one, two, or three or more embodiments may be combinable in whole or in part. Further, any feature of any embodiment of various aspects, including but not limited to any embodiment of the 1st to 15th aspects mentioned above, can be optionally selected with respect to other aspects or embodiments. Any aspect or embodiment of a method can be executed by a system or apparatus of another aspect or embodiment, and any aspect or embodiment of a system or apparatus can be configured to execute a method of another aspect or embodiment, including but not limited to any embodiment of the 1st to 15th aspects mentioned above.

[0041] The summary of this invention is provided to introduce a selection of concepts in a simplified form. The concepts are further described in the forms for carrying out the invention. Elements or steps other than those described in the summary of this invention are possible, and no element or step is necessarily required. The summary of this invention is not intended to identify the main features or essential features of the claimed subject matter, nor is it intended for use as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all of the disadvantages described in any part of this disclosure.

[0042] These and other features, aspects, and advantages are described below with reference to the drawings, which are intended to illustrate the present disclosure but not to limit the present disclosure. In the drawings, like reference characters consistently indicate corresponding features throughout the similar embodiments.

Brief Description of the Drawings

[0043]

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[0044] The following description illustrates in detail some embodiments of the present disclosure. Those skilled in the art will recognize that there are many variations and modifications of the present disclosure that are encompassed by the scope of the present disclosure. Accordingly, the description of a particular embodiment should not be considered as limiting the scope of the present disclosure.

[0045] FIG. 1 is a diagram depicting an exemplary medical device system according to an embodiment of the present specification. The medical device system in the embodiment may include a continuous analyte monitoring system 100. The continuous analyte monitoring system 100 may include an analyte sensor system 102 having a skin sensor assembly 160 configured to be fastened to the skin of a recipient via a base (not shown).

[0046] In an embodiment, other forms of medical device systems may be utilized, including other forms of monitoring systems, drug delivery systems, or other treatment systems. In an embodiment, among other forms of skin-wearable medical devices, a skin-wearable medical device having a skin sensor assembly or a drug delivery medical device may be utilized.

[0047] As shown in FIG. 1, an analyte sensor system 102 can be operably connected to a recipient and a plurality of display devices 110-114 in accordance with certain aspects of the present disclosure. Exemplary display devices 110-114 can include computers such as smartphones, smartwatches, tablet computers, laptop computers, and desktop computers. In some embodiments, the display devices 110-114 can be Apple Watch, iPhone® and iPad® manufactured by Apple Inc., or devices with iOS, Windows, or Android operating systems. It should be noted that the display device 114 can alternatively or additionally be a drug delivery device that is a display device and can operate in cooperation with the analyte sensor system 102 to deliver a drug to the recipient. The analyte sensor system 102 can include a sensor electronics module 140 and a continuous analyte sensor 138 associated with the sensor electronics module 140. The sensor electronics module 140 can directly wirelessly communicate with one or more of the plurality of display devices 110-114 via a wireless communication signal. As will be discussed in more detail below, the display devices 110-114 can also communicate with each other and / or communicate with the analyte sensor system 102 through each other. For ease of reference, the wireless communication signal from the analyte sensor system 102 to the display devices 110-114 can be referred to as an "uplink" signal 128. For example, the wireless communication signal from the display devices 110-114 to the analyte sensor system 102 can be referred to as a "downlink" signal 130. The wireless communication signal between two or more of the display devices 110-114 can be referred to as a "crosslink" signal 132. In addition, the wireless communication signal can include data transmitted by one or more of the display devices 110-113 via a "long distance" uplink signal 136 (e.g., a cellular signal) to one or more remote servers 190, or network entities such as cloud-based servers or databases, and can receive a long distance downlink signal 142 transmitted by the remote server 190.

[0048] In the embodiment shown by FIG. 1, one of the plurality of display devices can be a custom display device 111 specially designed to display certain types of displayable sensor information (e.g., in some embodiments, numerical values and arrows) associated with the analyte values received from the sensor electronics module 140. In some embodiments, one of the plurality of display devices can be a handheld device 112 such as a mobile phone, a palmtop computer, etc. based on the Android operating system, the iOS operating system, or other operating systems. The handheld device 112 can have a relatively large display and can be configured to display a graphical representation of continuous sensor data (e.g., including current and past data). Other display devices can include a tablet 113, a smartwatch 110, a drug delivery device 114, a blood glucose meter, and / or other handheld devices such as a desktop or laptop computer.

[0049] In addition to or instead of the display device, in the case of the display device 114 which can be a drug delivery device, it should be understood that the alerts and / or sensor information provided by the continuous analyte sensor 138 to the sensor electronics module 140 can be used to initiate and / or regulate the delivery of the drug to the recipient.

[0050] In use, the sensing portion of the sensor 138 may be disposed under the recipient's skin, and the contact portion of the sensor 138 can be electrically connected to the sensor electronics module 140. The electronics module 140 can be engaged with a housing (e.g., a base) that can be attached to a patch that can engage the recipient's skin. The patch can be an adhesive patch in the embodiment. In some embodiments, the electronics module 140 is integrally formed with the housing. Further, the electronics module 140 can be disposable and can be directly connected to the patch.

[0051] The continuous analyte sensor system 100 can include any sensor configuration that provides an output signal indicative of the concentration of an analyte. The output signal, which can include, for example, sensor data such as raw data streams, filtered data, smoothed data, and / or otherwise transformed sensor data, is transmitted to a receiver.

[0052] In some embodiments, the analyte sensor system 102 includes a transcutaneous glucose sensor as described in U.S. Patent Application Publication No. 2011 / 0027127, the entire disclosure of which is incorporated herein by reference. In some embodiments, the sensor system 102 includes a continuous glucose sensor and comprises a transcutaneous sensor (e.g., as described in U.S. Patent No. 6,565,509, as described in U.S. Patent No. 6,579,690, and / or as described in U.S. Patent No. 6,484,046). 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 are incorporated herein by reference in their entireties.

[0053] Various signal processing techniques and examples of glucose monitoring systems suitable for use with the embodiments described herein are described in U.S. Patent Application Publication No. 2005 / 0203360 and U.S. Patent Application Publication No. 2009 / 0192745, the contents of which are incorporated herein by reference in their entireties. The sensor can extend through a housing, which can maintain the sensor 138 on, in, or under the skin and / or provide an electrical connection of the sensor 138 to the sensor electronics within the sensor electronics module 140.

[0054] In some embodiments, the descriptions of the base, housing, fixture, and / or transmitter of the on-skin sensor assembly 160 can be interchangeable. In other embodiments, the base and housing of the on-skin sensor assembly 160 can differ in that they can be separate components from the sensor electronics module 140, e.g., separate from a transmitter or receiver.

[0055] In some embodiments, the sensor 138 is in the form of a wire. The distal end of the wire can be formed, for example, to have a conical shape (to facilitate insertion of the wire into the recipient's tissue). The sensor 138 may include an elongated analyte sensor, which may include an elongated conductive body such as an elongated conductive core (e.g., a metal wire) or an elongated conductive core coated with one, two, three, four, five or more layers of material that may or may not be conductive. The elongated analyte sensor may be long and thin, but can be flexible and strong. For example, in some embodiments, the minimum dimension of the elongated conductive body 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, less than 0.002 inch, less than 0.001 inch, and / or less than 0.0005 inch.

[0056] The sensor 138 may have a circular cross-section. In some embodiments, the cross-section of the elongated conductive body can be oval, rectangular, triangular, polyhedral, star-shaped, C-shaped, T-shaped, X-shaped, Y-shaped, irregular, etc. In some embodiments, a conductive wire electrode is used as the core. In other embodiments, the sensor 138 can be disposed on a substantially flat substrate. One or two additional conductive layers may be added to such an electrode (e.g., using an intervening insulating layer provided for electrical isolation). The conductive layer may be made 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.

[0057] In some embodiments, the materials used to form the elongated conductive body (e.g., stainless steel, titanium, tantalum, platinum, platinum-iridium, iridium, certain polymers, and / or the like) can be strong and stiff and thus resistant to breakage. For example, in some embodiments, the ultimate tensile strength of the elongated conductive body is greater than 80 kPsi and less than 140 kPsi, and / or the Young's modulus of the elongated conductive body is greater than 160 GPa and less than 220 GPa. The yield strength of the elongated conductive body can be greater than 58 kPsi and less than 2200 kPsi.

[0058] The electronic device module 140 can be releasably or permanently coupled to the sensor 138. The electronic device module 140 can include electronic circuitry related to the measurement and processing of continuous analyte sensor data. The electronic device module 140 can be configured to execute algorithms related to the processing and calibration of sensor data. For example, the electronic device module 140 can provide various aspects of the functionality of a sensor electronics module as described in U.S. Patent Application Publication No. 2009 / 0240120 and U.S. Patent Application Publication No. 2012 / 0078071, the entire contents of which are incorporated herein by reference. The electronic device module 140 may include hardware, firmware, and / or software that enables the measurement of analyte levels via a glucose sensor such as the sensor 138.

[0059] For example, the electronic device module 140 may include a potentiostat, a power source for providing power to the sensor 138, 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 module 140 and one or more receivers, repeaters, and / or display devices such as devices 110-114. The electronic components can be fixed to a printed circuit board (PCB) or the like and can take various forms. The electronic components can take the form of integrated circuits (ICs) such as application-specific integrated circuits (ASICs), microcontrollers, and / or processors. The electronic device module 140 may include sensor electronics configured to process sensor information, such as storing data, analyzing data streams, calibrating analyte sensor data, estimating analyte values, comparing the estimated analyte values with measured analyte values corresponding to time, and analyzing variations in the estimated analyte values. 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, U.S. Patent Application Publication No. 2007 / 0032706, U.S. Patent Application Publication No. 2007 / 0016381, U.S. Patent Application Publication No. 2008 / 0033254, U.S. Patent Application Publication No. 2005 / 0203360, U.S. Patent Application Publication No. 2005 / 0154271, U.S. Patent Application Publication No. 2005 / 0192557, U.S. Patent Application Publication No. 2006 / 0222566, U.S. Patent Application Publication No. 2007 / 0203966, and U.S. Patent Application Publication No. 2007 / 0208245, the contents of which are hereby incorporated by reference in their entirety. The electronic device module 140 can communicate with devices 110-114 and / or any number of additional devices via any suitable communication protocol.Exemplary communication methods or protocols include radio frequency; Bluetooth; Universal Serial Bus; any wireless local area network (WLAN) communication standard including IEEE 802.11, 802.15, 802.20, 802.22 and other 802 communication protocols; ZigBee; wireless (e.g., cellular) communication; paging network communication; magnetic induction; satellite data communication; proprietary communication protocols, open source communication protocols, and / or any suitable wireless communication method.

[0060] Additional sensor information is described in U.S. Patent No. 7,497,827 and U.S. Patent No. 8,828,201. The entire disclosures of U.S. Patent No. 7,497,827 and U.S. Patent No. 8,828,201 are incorporated herein by reference.

[0061] 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 example can be any sensor described herein or incorporated by reference. The sensors shown or described herein can be configured to sense, measure, detect, and / or interact with any analyte.

[0062] The term "analyte" is a broad term and is given its ordinary and customary meaning to those of ordinary skill in the art (and is not limited to a special or customized meaning), and refers to a substance or chemical component in a biological fluid that can be analyzed (e.g., blood, interstitial fluid, cerebrospinal fluid, lymph fluid, urine, sweat, saliva, etc.), but is not limited thereto. Analytes can include natural substances, artificial substances, metabolites, or reaction products.

[0063] In some embodiments, the analyte for measurement by the sensing region, device, system, and method is glucose. However, other analytes include, but are not limited to, ketone bodies; acetyl-CoA; acarboxyprothrombin; acylcarnitine; adenine phosphoribosyltransferase; adenosine deaminase; albumin; alpha-fetoprotein; amino acid profile (arginine (Krebs cycle), histidine / urocanic acid, homocysteine, phenylalanine / tyrosine, tryptophan); 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 isoenzyme; cyclosporine A; d-penicillamine; deethylchloroquine; dehydroepiandrosterone sulfate; DNA (acetylation polymorphism, alcohol dehydrogenase, alpha1-antitrypsin, cystic fibrosis, Duchenne / Becker muscular dystrophy, glucose-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 vivax, sex differentiation, 21-deoxycortisol); desbutylhalofantrine; dihydropteridine reductase; diphtheria / tetanus antitoxin; erythrocyte arginase; erythrocyte protoporphyrin; esterase D; fatty acid / acylglycine; 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; glucose-6-phosphate dehydrogenase; glutathione;Glutathione peroxidase; Glycolic acid; Glycosylated hemoglobin; Halofantrine; Hemoglobin variant; Hexosaminidase A; Human erythrocyte carbonic anhydrase I; 17-α-hydroxyprogesterone; Hypoxanthine phosphoribosyl transferase; 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; Quinine; Reverse tri-iodothyronine (rT3); Selenium; Serum pancreatic lipase; Sisomicin; Somatomedin C; Specific antibodies (adenovirus, antinuclear antibody, anti-zeta antibody, arbovirus, pseudorabies virus, dengue fever virus, guinea worm, tapeworm, amoeba dysentery, enterovirus, giardiasis, Helicobacter pylori, hepatitis B virus, herpes virus, HIV-1, IgE (atopic disease), influenza virus, Donovan Leishmania, leptospira, mumps / epidemic parotitis / rubella, mycoplasma pneumoniae, myoglobin, guinea worm, parainfluenza virus, malaria parasite, poliovirus, pseudomonas aeruginosa, respiratory syncytial virus, rickettsia (scrub typhus), Schistosoma mansoni, toxoplasma, Treponema pallidum, Trypanosoma cruzi / Langeri, vesicular stomatitis virus, bancroftian filariasis, 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; Leukocytes;and zinc protoporphyrin. Salts, sugars, proteins, fats, vitamins, and hormones that naturally exist in blood or interstitial fluid can also, in certain embodiments, constitute the analyte. The analyte can be naturally present in a biological fluid or can be endogenous, e.g., a metabolite, hormone, antigen, antibody, etc. Alternatively, the analyte can be introduced into the body or can be exogenous, e.g., a contrast agent for imaging, a radioisotope, a chemical agent, a fluorocarbon-based synthetic blood, or a drug or pharmaceutical composition, including, for example, 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); antidepressants (barbiturates, methaqualone, Valium, Librium, Miltown, Serax, Equanil, Tranxene, etc., which are tranquilizers); hallucinogens (fenciclonium, lysergic acid, mescaline, peyote, psilocybin); narcotics (heroin, codeine, morphine, opium, meperidine, Percocet, Percodan, Tussionex, fentanyl, Darvon, Talwin, Lomotil); synthetic narcotics (fentanyl, meperidine, amphetamine, methamphetamine, and analogs of fenciclonium, e.g., ecstasy); anabolic steroids;And nicotine, among others, but not limited to these. Metabolites of drugs and pharmaceutical compositions are also intended analytes. For example, ascorbic acid, uric acid, dopamine, norepinephrine, 3-methoxytyramine (3MT), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxytryptamine (5HT), 5-hydroxyindoleacetic acid (FHIAA), and analytes such as other chemical substances generated in the body and neurochemical substances, such as intermediates of the citric acid cycle, can also be analyzed.;

[0064] Any of the features described at least in connection with FIG. 1 can be applicable to all aspects and embodiments specified herein. Further, any of the features of an embodiment can be independently combined, in part or in whole, in any manner with other embodiments described herein. For example, one, two, or three or more embodiments can be combined, in whole or in part. Further, any of the features of an embodiment can be optionally selected for 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.

[0065] FIG. 2A illustrates a perspective view of an exemplary wearable medical device in the form of a skin sensor assembly 200 configured to be deployed on the skin. The skin sensor assembly 200 may include a housing or base 202. The housing or base 202 may be configured to be worn on the skin of a recipient and may include a distal surface for facing the skin and a proximal surface 203 facing opposite the distal surface. The housing or base 202 may include an opening 205 for retracting an insertion element proximally therethrough from the skin. A patch 204, such as an adhesive patch, can couple the base 202 to the skin 206 of the recipient. The patch 204 may be positioned on the distal surface of the housing or base 202. In some embodiments, the adhesive patch 204 engages the skin and includes an engagement surface that is bonded to an adhesive suitable for skin adhesion, such as a pressure-sensitive adhesive (e.g., acrylic, rubber-based, or other suitable type) bonded to a carrier substrate for skin attachment (e.g., spandex polyester, polyurethane film, or other suitable type) (however, any suitable type of adhesive is contemplated). The skin sensor assembly 200 can include an electronic device unit 208 (e.g., a transmitter) that may further include an analyte sensor, such as a transdermal analyte sensor (e.g., a glucose sensor) 212, and a glucose sensor module 210 coupled to the base 202.

[0066] The applicator system can engage the adhesive patch 204 to the skin 206. The glucose sensor module 210 may be secured to the base 202 (e.g., via retention elements such as snap-fit features and / or interference features, adhesives, welding, etc.) to ensure that the analyte sensor 212 (e.g., a glucose sensor) is coupled to the base 202. In alternative embodiments, the sensor module 210 and the base 202 are pre-assembled or manufactured as a single component.

[0067] After the sensor assembly 200 is deployed on the user's skin, the user (or applicator) can connect the electronic device unit 208 (e.g., a transmitter) to the skin-mounted sensor assembly 200 via retention elements such as snap-fit features and / or interference features. The electronic device unit 208 can measure and / or analyze glucose metrics sensed by a transcutaneous analyte sensor (e.g., a glucose sensor) 212. The electronic device unit 208 can transmit information (e.g., measurements, analyte data, glucose data) to remotely located devices (e.g., 110-114 shown in FIG. 1).

[0068] The skin-mounted sensor assembly 200 may be attached to a recipient using an applicator adapted to provide a convenient and safe application. Such an applicator may also be used to attach the electronic device unit 208 to the base 202, to insert the sensor 212 through the recipient's skin, and / or to connect the sensor 212 to the electronic device unit 208. Once the electronic device unit 208 is engaged with the base and the sensor 212 is inserted into (and connected to) the skin, the sensor assembly can be removed from the applicator.

[0069] FIG. 2B illustrates a perspective view of the electronic device unit 208 connected to the base 202 via retention elements such as snap-fit features and / or interference features. In some embodiments, the electronic device unit 208 and the base 202 are connected by an adhesive, welding, or other bonding technique. The patch 204 on the distal surface of the base 202 is configured to connect the sensor assembly 200 to the skin.

[0070] FIG. 2C illustrates a perspective view of the skin-mounted sensor assembly 200. The skin-mounted sensor assembly 200 may be disposable or reusable. FIG. 2C further illustrates the electronic device unit 208 connected to the base 202 and the adhesive patch 204 configured to be attached to the skin-mounted sensor assembly 200, which, when combined, can be held within an applicator.

[0071] Figure 3 illustrates an example of a wearable medical device on the skin in the form of a skin sensor assembly 300 with an electronic device unit 302 configured to be inserted into the cavity 304 of the base or housing 306. The base or housing 306 may be configured to be worn on the skin of the recipient and may include a distal surface for facing the skin and a proximal surface 305 facing the opposite side of the distal surface. The electronic device unit 302 may be connected to a portion of the housing 306 and may include one or more tabs 308 that enable the electronic device unit 302 to be held by the housing 306. The housing 306 may include an opening 310 for retracting the insertion element proximally through the skin. The opening 310 may enable an insertion element (such as a needle) to pass through for deploying the transcutaneous analyte sensor 312 onto the skin. The patch 314 may further include an opening 316 that enables the sensor 312 and the insertion element to pass through. The electronic device unit 302 may be connected to the housing 306 before or after deployment of the sensor 312 onto the skin of the recipient.

[0072] Figure 4 illustrates an example of a wearable medical device on the skin in the form of a skin sensor assembly 400 in which the electronic device unit is integrated with the housing 402. The housing 402 may be configured to be worn on the skin of the recipient and may include a distal surface for facing the skin and a proximal surface 403 facing the opposite side of the distal surface. The skin sensor assembly 400 is shown on the skin 404 with the patch 406 engaged with the skin 404.

[0073] The embodiments of FIGS. 2A-4 may each include an engagement surface for engaging the skin. The engagement surface may, in an embodiment, be positioned on the patch, for example, on the distal surface of the patch, or may, in an embodiment, have another position. The engagement surface may, in an embodiment, include an adhesive surface configured to adhere to the skin. The adhesive may be configured to adhere to the skin. Additional adhesive information is described in U.S. Patent No. 11,219,413, filed Aug. 25, 2015. The entire disclosure of U.S. Patent No. 11,219,413 is incorporated herein by reference. In an embodiment, the engagement surface may be covered with a liner prior to deployment to the recipient's skin.

[0074] FIG. 5 illustrates a system for deploying a wearable medical device on the skin to the skin. The system may, in an embodiment, include an applicator system. The system may include an applicator for a skin sensor assembly of an analyte sensor system, according to some embodiments. In an embodiment, other forms of systems may be utilized.

[0075] The applicator 500 may include an applicator housing 501 that may include an outer housing 504 and an inner housing 506, and other forms of housings in an embodiment. The applicator housing 501 may, in an embodiment, be configured to hold a wearable medical device on the skin. The applicator 500 may include a deployment mechanism configured to deploy the wearable medical device on the skin to the skin. The deployment mechanism may, for example, in an embodiment, include one or more holding elements for holding the wearable medical device on the skin and releasing the wearable medical device on the skin from the applicator housing 501. The deployment mechanism may include an insertion assembly for inserting at least a portion of the wearable medical device on the skin into the skin. The insertion assembly may drive a portion of the wearable medical device on the skin, such as an insertion element and a sensor, into the recipient's skin. The deployment mechanism may include a retraction assembly for retracting a portion of the wearable medical device on the skin, such as an insertion element, from the skin.

[0076] In an embodiment, the applicator 500 may include an actuating element 502 disposed on a side surface of the applicator 500, for example, on a side surface of the outer housing 504 of the applicator 500. In some embodiments, the actuating element 502 may be a button, switch, toggle, slide, trigger, knob, rotating member, a portion of the applicator 500 that deforms and / or bends, or any other suitable mechanism for actuating an insertion and / or retraction assembly of the applicator 500. In some embodiments, the actuating element 502 may be disposed at any location, for example, at the top, upper side, lower side, or any other location of the applicator 500. The applicator 500 may be large enough for a recipient to grip by hand and, for example, press the actuating element 502 with a thumb, or index finger and / or middle finger, or otherwise actuate it.

[0077] The applicator 500 may be configured to have one or more safety features such that activation of the applicator 500 is prevented until the safety features are deactivated. In one example, the one or more safety features prevent the applicator 500 from operating unless the applicator 500 is pressed against the recipient's skin with sufficient force. Further, as will be described in more detail in connection with one or more of FIGS. 6-20B below, the applicator 500 may be further configured such that one or more components thereof retract based at least in part on one or more components pressing against the recipient's skin with a force exceeding a predetermined threshold, rather than based on one or more components translating beyond a predetermined static distal position. In other words, the applicator 500 may implement force-based retraction triggering rather than being limited to displacement-based retraction triggering.

[0078] Figure 6 illustrates an exploded perspective view of the applicator 500 of FIG. 5 according to some embodiments. The applicator 500 may include an outer applicator housing 504 with an actuating element 502. The outer applicator housing 504 may be configured in an embodiment to be gripped by a user. The outer applicator housing 504 may be configured to translate linearly in a distal direction by aligning the actuating element 502 to a position where a recipient applies a force to the applicator 500 (specifically, the inner housing 506), thereby enabling the applicator 500 to fire. A further description of the alignment process is described below.

[0079] The applicator 500 further includes an inner housing 506 configured to house at least one or more mechanisms for applying the on-skin sensor assembly 508 to the recipient's skin. The distal surface 510 of the bottom opening of the inner housing 506 can define the bottom surface of the applicator 500. In some embodiments, when the applicator 500 is pressed against the recipient's skin, the skin can deform substantially convexly at the distal surface 510 such that at least a portion of the surface of the skin disposed at the bottom opening of the inner housing 506 of the applicator extends proximally into the bottom opening of the inner housing 506 beyond the plane defined by the distal surface 510.

[0080] As shown in FIG. 7, the housing 501, particularly the inner housing 506, can include an internal cavity 503 for holding an on-skin wearable medical device. The internal cavity 503 may have a distal end portion 505 at an opening for deploying the on-skin wearable medical device therefrom. The proximal end portion 507 of the internal cavity 503 can include an on-skin wearable medical device coupled to the needle carrier assembly 516.

[0081] Referring back to FIG. 6, in some embodiments, the first barrier layer 512 may be disposed to cover one or more openings within the inner housing 506, such as an opening 514 that may be configured such that at least a portion of the actuating element 502 extends therethrough during actuation of the applicator 500. In such embodiments, a portion of the actuating element 502 may be configured to pierce or deform the first barrier layer 512 during actuation of the applicator 500. The first barrier layer 512 may include a gas-permeable material such as Tyvek, or a gas-impermeable material such as a metal foil, polymer film, elastomer, or any other suitable material.

[0082] The applicator 500 may further include a needle carrier assembly 516 that includes a needle hub 518 configured to couple the insertion element 520 to the needle carrier assembly 516. In some other embodiments, the insertion element 520 may be directly coupled to the needle carrier assembly 516. The insertion element 520 is configured to insert the sensor of the skin-on sensor assembly 508 into the skin of the recipient. In some embodiments, the insertion element includes a needle, such as a laterally open needle, a needle with tip deflection, a curved needle, a polymer-coated needle, a hypodermic needle, or any other suitable type of needle or structure. In still other embodiments, the insertion element 520 may be integrally formed with the sensor and be rigid enough to be partially inserted into the skin of the recipient with a minimal structural support or without a structural support.

[0083] The applicator 500 may further include a holder 522 releasably coupled to the needle carrier assembly 516, and the holder 522 is configured to guide, for example, the needle carrier assembly 516 and the on-skin sensor assembly 508 coupled to the needle carrier assembly 516 during straight movement from at least a proximal position to a distal insertion position. As will be described in more detail below, the on-skin sensor assembly 508 may be removed or released from the holder 522 and / or the needle carrier assembly 516 when the on-skin sensor assembly 508 is disposed on the skin of the recipient. For example, one or more retaining elements may release the on-skin wearable medical device from the applicator housing 501.

[0084] The applicator 500 may further include an insertion assembly configured to translate the insertion element 520, the needle hub 518, the needle carrier assembly 516, and the on-skin sensor assembly 508 from a proximal position in a distal direction to a distal insertion position. Such an insertion assembly may include at least one spring for inserting at least a portion of the on-skin wearable device into the skin. The insertion assembly may include a first spring 524. The first spring 524 may be a compression spring or any suitable type of spring and may have a first end in contact or coupled with the inner applicator housing 506 and a second end in contact or coupled with the holder 522. The first spring 524 is configured to translate the holder 522, the needle carrier assembly 516, the needle hub 518, the insertion element 520, and the on-skin sensor assembly 508 in a distal direction to the distal insertion position during operation of the insertion assembly. At substantially the distal insertion position, the needle carrier assembly 516 may separate from the holder 522 and the on-skin sensor assembly 508.

[0085] The applicator 500 may further include a retraction assembly for retracting the insertion element (e.g., a needle) from the skin. The retraction assembly may be configured to translate the needle carrier assembly 516, the needle hub 518, and the insertion element 520 proximally from a distal insertion position to a proximal retraction position. In some embodiments, the initial proximal position may be the same as the proximal retraction position. In other embodiments, the initial proximal position may be different from the proximal retraction position. Such a retraction assembly may include at least one spring. The retraction assembly may include a second spring 526. The second spring 526 may be a compression spring or any suitable type of spring and may have a first end that contacts or is coupled to the holder 522 until at least retraction, and a second end that contacts or is coupled to at least one spring retaining element (e.g., 528a, 528b in FIGS. 10-14). The second spring 526 is configured to linearly move the needle carrier assembly 516, the needle hub 518, and the insertion element 520 proximally from the distal insertion position to the proximal retraction position in response to the skin sensor assembly 508 contacting the recipient's skin and / or the first end of the second spring 526 reaching a movement limit with a force exceeding a predetermined threshold sufficient to overcome at least one spring retaining element (e.g., 528a, 528b in FIGS. 10-14). In some embodiments, a stop feature (not shown) may be disposed at the bottom of the applicator 500, e.g., on the distal portion of the inner housing 506. Such a stop feature may be configured to contact one or more of the skin sensor assembly 508, the needle carrier assembly 516, or the holder 522 at the distal insertion position.

[0086] In some embodiments, the second barrier layer 530 may be disposed to cover the bottom opening of the inner housing 506. The second barrier layer 530 may include a gas-permeable material such as Tyvek, or a gas-impermeable material such as metal foil or film. In some embodiments, the second barrier layer 530 may be removed by the recipient before use of the applicator 500. In embodiments comprising one or both of the first barrier layer 512 and the second barrier layer 530, such layers may provide a sterile environment between the applicator 500 and the external environment and / or may allow gas entry and release, such as during sterilization.

[0087] A brief description of some aspects of the operation of the applicator 500 follows below with respect to FIGS. 7-9, which illustrate some cross-sectional views of the applicator 500 in operation, according to some embodiments, as shown in FIGS. 5 and 6. FIGS. 7-9 may correspond, for example, to the applicator 500 cut along the cut line A-A' shown in FIG. 5.

[0088] FIG. 7 illustrates the state of the applicator 500 before operation. The holder 522 includes an insertion assembly retaining element 532, which is configured to fix the holder 522, the needle carrier assembly 516, the needle hub 518, the insertion element 520, and the on-skin sensor assembly 508 in a pre-operation state by contacting the inner housing 506.

[0089] The needle carrier assembly 516 includes a plurality of wearable retaining and / or alignment elements 534a, 534b, which extend through the holder 522 and are configured to releasably couple the on-skin sensor assembly 508 to the holder 522 and / or the needle carrier assembly 516. The wearable retaining elements 534a, 534b may comprise, for example, arms, flexure elements, tabs, detents, snaps, or any other feature capable of providing a retaining function. In some embodiments, the wearable retaining elements 534a, 534b may extend around the holder 522 rather than through it. Although two wearable retaining elements are shown, any number of wearable retaining elements are contemplated. In some embodiments, the wearable retaining elements 534a, 534b may include snap fits, friction fits, interference features, elastomeric grips, and / or adhesives configured to couple the on-skin sensor assembly 508 to the needle carrier assembly 516 and / or the holder 522.

[0090] The inner housing 506 may include a spring 536 configured to contact the outer housing 504 and maintain a predetermined spacing between the outer housing 504 and the inner housing 506 in the pre-operation orientation of FIG. 7. The spring 536 may be a compression spring, leaf spring, flexure arm spring, foam or rubber piece, or the like. In some other embodiments, the outer housing 504 may include a spring 536 configured to contact the inner housing 506 in a manner opposite to that shown in FIG. 7.

[0091] The operation of the applicator 500 may include the recipient pressing the applicator 500 against their skin with sufficient force to linearly move the outer housing 504 towards and distally relative to the inner housing 506, as indicated by arrow 538, until the actuating element 502 is aligned with the opening 514 of the inner housing 506 and the insertion assembly retaining element 532 of the holder 522. The insertion assembly retaining element 532 may comprise, for example, an arm, a flexure element, a tab, a detent, a snap, or any other feature capable of providing a retaining function. Once such alignment is achieved, the recipient may initiate (e.g., press) the actuating element 502, as indicated by arrow 540, thereby sufficiently flexing the insertion assembly retaining element 532 to release the holder 522 from the inner housing 506. In some other embodiments, the applicator 500 may be configured such that the actuating element 502 may be actuated first, but actual insertion is not triggered until the outer housing 504 is linearly moved sufficiently towards and distally relative to the inner housing 506. In yet other embodiments, the actuating element 502 may be biased towards the center of the applicator 500 such that it need not be explicitly actuated by the recipient, but instead may be configured to automatically initiate insertion when the outer housing 504 is linearly moved sufficiently towards and distally relative to the inner housing 506.

[0092] Such a configuration provides several advantages. First, the linear movement of the outer housing 504 relative to the inner housing 506 prior to actuation provides a means of drop protection such that the applicator 500 cannot be prematurely fired if it accidentally drops. Second, the spring 536 provides a biasing force that the recipient must actively overcome by pressing the applicator 500 into their skin prior to firing, thereby reducing the likelihood of actuating it before it is properly positioned. Further, the recipient may decide not to fire the applicator 500 and to discontinue pressing the applicator 500 against the skin, in which case the spring 536 biases against the outer housing 504 and allows the outer housing 504 to return to its initial state.

[0093] The holder 522, the needle carrier assembly 516, the needle hub 518, the insertion element 520, the on-skin sensor assembly 508, the first spring 524, and the second spring 526 are all shown in their pre-operational positions in FIG. 7.

[0094] FIG. 8 illustrates the applicator 500 prior to retraction of the needle carrier assembly 516, while the on-skin sensor assembly 508 is being inserted. The first spring 524 drives the holder 522, the needle carrier assembly 516, the needle hub 518, the insertion element 520, and the on-skin sensor assembly 508 in a distal direction toward the distal insertion position. FIG. 8 illustrates a position where the on-skin sensor assembly 508 is in contact with the recipient's skin, but the holder 522 has not yet been fully driven so as to contact the on-skin sensor assembly 508 or the recipient's skin by the first spring 524.

[0095] In some embodiments, the mass of each of the holder 522, the needle carrier assembly 516, the needle hub 518, the insertion element 520, and the on-skin sensor assembly 508 may be specifically designed to reduce or substantially eliminate the tendency for the needle carrier assembly 516, the needle hub 518, the insertion element 520, and the on-skin sensor assembly 508 to be removed from the holder 522 due to inertial forces while being driven in the distal direction during insertion. In some embodiments, the force exerted by the first spring 524 may be selected to be sufficient for proper operation of the applicator 500, but not so large as to further exacerbate such an inertially triggered removal as described above. In some embodiments, a spring (not shown) may be configured to exert a force sufficient to prevent the needle carrier assembly 516 from being inertially triggered and removed from the holder 522 during insertion, against a portion of the needle carrier assembly 516, for example, in the distal direction.

[0096] FIG. 9 illustrates applicator 500 in operation when needle carrier assembly 516, needle hub 518, and insertion element 520 are retracted proximally by second spring 526. In FIG. 9, first spring 524 has fully driven skin-on sensor assembly 508 against the recipient's skin. In this position, second spring 526 is released from spring retaining elements (e.g., 528a, 528b of FIGS. 10-14) and drives needle carrier assembly 516, needle hub 518, and insertion element 520 proximally from the distal insertion position. When needle carrier assembly 516 reaches the proximal retracted position, needle carrier retaining element 542 of holder 522 engages needle carrier assembly 516, thereby maintaining needle carrier assembly 516, needle hub 518, and insertion element 520 in a locked retracted position that restricts access to insertion element 520. Needle carrier retaining element 542 may comprise, for example, an arm, a flexure element, a tab, a detent, a snap, or any other feature capable of a retaining function. In this retracted position, needle carrier assembly 516, needle hub 518, and insertion element 520 are prevented from moving distally.

[0097] Further description of some aspects of the operation of applicator 500 follows below with respect to FIGS. 10-12, which illustrate some cross-sectional views of applicator 500 in operation according to some embodiments, corresponding, for example, to applicator 500 cut along cut line B-B' shown in FIG. 5. For ease of illustration, needle hub 518 and insertion element 520 are not shown in FIGS. 10-12.

[0098] Figure 10 illustrates the state of the applicator 500 before actuation. For ease of illustration, the skin sensor assembly 508 is not illustrated in Figure 10. The holder 522 comprises spring retaining elements 528a, 528b configured to contact and hold the first end of the second spring 526 in a pre-actuation state while the second end of the spring 526 is in contact with the needle carrier assembly 516, for example during insertion. The spring retaining elements 528a, 528b may comprise, for example, arms, flexure elements, tabs, detents, snaps, or any other feature capable of a retaining function. Two spring retaining elements 528a, 528b are shown, but at least one spring retaining element is contemplated. In some embodiments, the applicator 500 may include one spring retaining element, as shown in Figures 21-24. In some embodiments, the applicator 500 may include three spring retaining elements. In some embodiments, the applicator 500 may include four spring retaining elements. In some embodiments, the spring retaining elements 528a, 528b are flexible arms, rigid arms, deformable features, snaps, catches, or hooks. In some embodiments, the spring retaining elements 528a, 528b may be actively flexed by one or more features within the applicator 500.

[0099] The needle carrier assembly 516 comprises backstop features 544a, 544b configured to prevent lateral flexure of the spring retaining elements 528a, 528b at the proximal starting position, at least during insertion, thereby supporting the retention of the second spring 526 between the spring retaining elements 528a, 528b and the holder 522 until retraction. Two backstop features are illustrated, but any number of backstop features are contemplated. The number of backstop features may be equal to the number of spring retaining elements.

[0100] Figure 13 illustrates an enlarged view of the spring retaining element 528b and the backstop feature 544b. In Figure 13, the first spring 524 is driving the holder 522, the needle carrier assembly 516, and the on-skin sensor assembly 508 distally toward the distal insertion position. The backstop feature 544b is shown engaged with the spring retaining element 528b, preventing the spring retaining element 528b from deflecting laterally, thereby preventing the second spring 526 from being released. As shown in Figure 13, the proximal end of the spring retaining element 528b can be offset by a distance α from the distal end of the backstop feature 544b. In some embodiments, the distance α is the length required for the spring retaining element 528b to traverse along the backstop feature 544b such that the spring retaining element 528b passes through the backstop feature 544b. The backstop feature 544b may feature a ramp for guiding the spring retaining element 528b. The distal ends of the needle carrier assembly 516 and the holder 522 may be offset from each other by at least the same distance α to allow the spring retaining element 528b to traverse distally beyond the backstop feature 544b.

[0101] It can be understood that the frictional force between the corresponding contact surfaces of the backstop feature 544b and the spring retaining element 528b can at least partially determine the amount of force for releasing the spring retaining element 528b from the backstop feature 544b. This force can allow lateral deflection of the spring retaining element 528b and thus allow expansion of the second spring 526. In some embodiments, the amount of force is at least 0.1 pound. In some embodiments, the amount of force is at least 0.5 pound. In some embodiments, the amount of force is at least 1 pound. In some embodiments, the amount of force is at least 2 pounds. In some embodiments, the amount of force is at least 3 pounds. In some embodiments, the amount of force is at least 4 pounds. In some embodiments, the amount of force is at least 5 pounds.

[0102] The figure shows a backstop feature 544b that prevents lateral deflection of the spring retaining element 528b in the radially outward direction, but it is contemplated that the reverse structural relationship can be achieved. For example, the inclined surface of the spring retaining element 528b can be reversed to face the opposite direction as shown in FIG. 13. Further, the inclined surface of the spring retaining element 528b may be biased in the radially inward direction by a second spring 526 relative to the backstop feature 544b. In such an embodiment, the backstop feature 544b can be located radially inward of the spring retaining element 528b.

[0103] Accordingly, in some embodiments, the materials utilized to form the holder 522 and the needle carrier assembly 516 can be selected based on the amount of force desired to release the spring retaining element 528b due to lateral deflection. Examples of such materials can include polycarbonate, ABS, PC / ABS, polypropylene, HIPS (High impact polystyrene), polybutylene terephthalate (PBT), polyoxymethylene (POM), acetal, polyacetal, polyformaldehyde, PTFE, high density polyethylene (HDPE), ultra-high-molecular-weight polyethylene (UHMWPE), nylon, polyethylene terephthalate (PET), thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), TPSiv, cyclo-olefin polymer (COP), cyclo-olefin copolymer (COC), and / or liquid-crystal polymer (LCP).

[0104] The angle θ of a portion of the spring retaining element 528b that contacts the second spring 526 can also affect the amount of frictional force to deflect the spring retaining element 528b laterally and thus release the second spring 526. Thus, the angle θ may be selected based on a desired amount of force to deflect the spring retaining element 528b laterally enough to release the second spring 526. In some embodiments, the angle θ is at least 1 degree relative to the vertical axis of the spring retaining element 528b. In some embodiments, the angle θ is at least 5 degrees. In some embodiments, the angle θ is at least 10 degrees. In some embodiments, the angle θ is at least 15 degrees. In some embodiments, the angle θ is at least 20 degrees. In some embodiments, the angle θ is about 30 - 45 degrees. Additionally, the force profile of the second spring 526 can affect the target amount of frictional force to deflect the spring retaining element 528b laterally. Thus, in some embodiments, the force profile of the second spring 526 can be considered when selecting one or both of the materials for forming the holder 522 and the needle carrier assembly 516, and the angle θ of a portion of the spring retaining element 528b that contacts the second spring 526.

[0105] The angle β of the spring retaining element 528b relative to the vertical axis can also affect the amount of frictional force to deflect the spring retaining element 528b laterally and thus release the second spring 526. By contacting the spring retaining element 528b, the second spring 526 can apply a force to the spring retaining element 528b at a distance d from the bottom of the spring retaining element 528b, thereby generating a torque moment sufficient to induce lateral deflection of the spring retaining element 528b.

[0106] As shown in more detail in FIG. 14, FIG. 13 further illustrates a needle carrier assembly 516 comprising a flexure element 546 configured such that a second spring 526 first deflects a spring retaining element 528b and then contacts the spring retaining element 528b and maintains the spring retaining element 528b in a laterally deflected orientation after sufficiently driving the needle carrier assembly 516 in the proximal direction. The flexure element 546 prevents the spring retaining element 528b from contacting the windings of the second spring 526 while the second spring 526 is extended, smoothes the operation of the applicator 500, and may prevent energy designed to be released by the second spring 526 to drive the needle carrier assembly 516 in the proximal direction during release of the second spring 526 from being absorbed by an undesired contact with the spring retaining element 528b.

[0107] In some embodiments, the angle θ of a portion of the spring retaining element 528b that contacts the second spring 526 may be substantially 90° (e.g., flat), and the flexure element 546 may have an inclined or angled surface that contacts the spring retaining element 528b in the position illustrated in FIG. 13. In such embodiments, the flexure element 546 may be configured to first deflect the spring retaining element 528b when the first spring 524 drives the holder 522 from the position illustrated in FIG. 13 to the position illustrated in FIG. 14, in addition to the functionality described above.

[0108] In some embodiments, the inner housing 506 may comprise a protrusion 548 that extends distally from the inner housing 506. The protrusion 548 may be configured to contact at least one of the spring retaining elements 528a, 528b and the backstop features 544a, 544b in a pre-operational state, such that the spring retaining elements 528a, 528b are prevented from deflecting laterally until the holder 522 and the needle carrier assembly 516 translate distally by at least a predetermined minimum distance. Accordingly, the protrusion 548 can provide a means of drop protection so that the applicator 500 does not fire prematurely in response to a shock shock caused by dropping before intentional operation.

[0109] Returning to FIG. 10, the inner housing 506 may further include an engagement element 550 configured to engage a protrusion 552 of the needle carrier assembly 516 when the needle carrier assembly 516 linearly moves distally beyond a predetermined threshold, thereby preventing the needle carrier assembly 516 from linearly moving distally beyond the predetermined threshold. This is contemplated to ensure retraction of the needle carrier assembly in the event of an air or dry firing that is actuated in some way when the applicator 500 is not held against the recipient's skin. In some embodiments, the predetermined threshold may correspond to the distal end of the needle carrier assembly 516 extending beyond a point proximal to the distal end of the inner housing 506, substantially coinciding with the distal end of the inner housing 506, or extending to a point distal to the distal end of the inner housing 506. In some embodiments, the engagement element 550 includes a hook, a U-shaped structure, a loop, a protrusion, or any other structure capable of engaging the protrusion 552 as described above.

[0110] FIG. 11 illustrates the applicator 500 after actuation at the start of the force retraction feature process at or near the distal insertion position where the on-skin sensor assembly 508 can contact the recipient's skin. The first spring 524 drives the holder 522, the needle carrier assembly 516, the needle hub 518, the insertion element, and the on-skin sensor assembly 508 in a distal direction toward the distal insertion position. During proper operation, the holder 522 and the on-skin sensor assembly 508 should be pressed against the recipient's skin. However, FIG. 11 can also illustrate a dry-fire condition where the applicator 500 is not properly pressed against the recipient's skin before triggering the applicator 500. Thus, when the first spring 524 drives the holder 522 and the needle carrier assembly 516 in the distal direction beyond a predetermined threshold, the engagement element 550 contacts the protrusion 552, thereby preventing the needle carrier assembly 516 from moving further distally, while the holder 522 is driven further distally such that the backstop features 544a, 544b of the needle carrier assembly 516 no longer contact the spring retaining elements 528a, 528b at the distal insertion position, thereby releasing the first end of the second spring 526 and initiating retraction even when the applicator 500 has been dry-fired. The insertion force provided by the first spring 524 can be sufficient to overcome the frictional force between the corresponding contact surfaces of the backstop feature 544b and the spring retaining element 528b.

[0111] Looking at FIG. 14, the first spring 524 drives the holder 522, the needle carrier assembly 516, and the on-skin sensor assembly 508 in a distal direction with respect to the recipient's skin. When the first spring 524 drives the holder 522, the needle carrier assembly 516, and the on-skin sensor assembly 508 with respect to the recipient's skin, the skin provides a reaction force against the force generated by the first spring 524. The skin may oppose the force of the first spring 524 and bias against the distal end of the on-skin sensor assembly 508. Since the distal end of the holder 522 is offset from the distal end of the on-skin sensor assembly 508 as shown in FIG. 13, when the first spring 524 continues to drive the holder 522 toward the skin while the on-skin sensor assembly 508 is pressed against the skin, the reaction force provided by the skin is transmitted to the holder 522. The reaction force provided by the skin enables the spring retaining element 528b to displace beyond the backstop feature 544b. When the spring retaining element 528b clears a distance α beyond the backstop feature 544b, the second spring 526 can deflect the spring retaining element 528b laterally, thereby releasing the second spring 526 to drive the needle carrier assembly 516 in a proximal direction. Alternatively, as described above in connection with FIG. 13, when the angle θ of the portion of the spring retaining element 528b in contact with the second spring 526 is substantially 90° (e.g., flat), the inclined or angled surface of the flexure element 546 in contact with the spring retaining element 528b deflects the spring retaining element 528b just enough to release the second spring 526, whereby the needle carrier assembly 516 is driven in a proximal direction.

[0112] In some embodiments, engagement element 550 can engage protrusion 552 even when applicator 500 is pressed against the user's skin. In such embodiments, engagement element 550 engages protrusion 552 when first spring 524 drives holder 522, needle carrier assembly 516, and skin-on sensor assembly 508 against the recipient's skin. As described above, engagement element 550 prevents needle carrier assembly 516 from moving distally when engagement element 550 engages protrusion 552. This allows spring retaining elements 528a, 528b to separate from backstop features 544a, 544b and allows release of second spring 526. Engagement of engagement element 550 with protrusion 552 adds force to the reaction force provided by the skin and thus can increase the energy required to overcome the frictional engagement between spring retaining elements 528a, 528b and backstop features 544a, 544b. In some cases, engagement of engagement element 550 with protrusion 552 provides an instantaneous impact force that converts at least a portion of the initial energy of first spring 524 into the energy required to overcome the frictional engagement between spring retaining elements 528a, 528b and backstop features 544a, 544b. Such embodiments are contemplated to provide benefits to users with soft skin or a higher body fat percentage.

[0113] Returning to FIG. 12, which illustrates the applicator 500 in operation, the needle carrier assembly 516 is retracted proximally by the second spring 526, as indicated by arrow 554. In FIG. 12, when the on-skin sensor assembly 508 contacts the recipient's skin with the backstop features 544a, 544b no longer fixing the spring retainer elements 528a, 528b, the first end of the second spring 526 presses the spring retainer elements 528a, 528b with sufficient force to deflect the spring retainer elements 528a, 528b to the distal insertion position, allowing the second spring 526 to clear the spring retainer elements 528a, 528b and drive the needle carrier assembly 516 proximally, thereby maintaining the needle carrier assembly 516, the needle hub 518 (see FIGS. 7-9), and the insertion element 520 (see FIGS. 7-9) in a locked retracted position even in the case of a dry fire.

[0114] FIGS. 15 and 16 illustrate enlarged views of some features of an applicator, such as the applicator 500, according to some embodiments.

[0115] In FIG. 15, the first spring 524 (see FIGS. 6-12) drives the holder 522, as well as the needle carrier assembly and the on-skin sensor assembly 508, distally in the direction indicated by arrow 556 toward the distal insertion position. The retaining element 534b of the needle carrier assembly is releasably coupled to the on-skin sensor assembly 508. As illustrated, during insertion and near the distal insertion position, the holder 522 contacts the spring retaining element 534b, preventing the spring retaining element 534b from deflecting laterally, thereby firmly fixing the on-skin sensor assembly 508 to the needle carrier assembly.

[0116] In FIG. 16, the second spring 526 (see FIGS. 6 - 12) drives the needle carrier assembly 516 in the proximal direction from the distal insertion position. Since the holder 522 is driven sufficiently in the distal direction, at the distal insertion position, the holder 522 is no longer in contact with the wearable retaining element 534b. Thus, the wearable retaining element 534b can flex freely laterally, thereby releasing the on - skin sensor assembly 508 from the wearable retaining element 534b and thus from the needle carrier assembly 516. The needle carrier assembly 516 is here driven in the proximal direction by the second spring 526, while the on - skin sensor assembly 508 is fixed to the recipient's skin. Further, in some embodiments, since the holder 522 is driven to the distal insertion position and substantially held in that position by the first spring 524, the holder 522 can press on one or both of the on - skin sensor assembly 508 or the adhesive patch of the on - skin sensor assembly 508 and can support one or both during attachment to the recipient's skin.

[0117] FIG. 17 illustrates a perspective partial cutaway view of the needle carrier assembly 516, the needle hub 518, and the on - skin sensor assembly 508 of the applicator 500 of FIGS. 5 and 6, according to some embodiments. FIG. 18 illustrates a cross - sectional view of the needle hub 518 and the on - skin sensor assembly 508, according to some embodiments. FIG. 19 illustrates a top view of a portion of the needle carrier assembly 516 and the needle hub 518, according to some embodiments. The following is a description of these features with reference to FIGS. 17 - 19.

[0118] The on - skin sensor assembly 508 includes a sensor assembly opening 560. The needle hub 518 is configured to couple the insertion element 520 to the needle carrier assembly 516 and to substantially maintain the desired orientation of the insertion element 520 during insertion of the sensor of the on - skin sensor assembly 508 into the recipient's skin.

[0119] The needle hub 518 includes a plurality of upper arms 562a, 562b, a plurality of lower arms 564a, 564b, and a base 566. Although two upper arms and two lower arms are illustrated, any number of arms are contemplated, such as a single upper and lower arm. In some embodiments, the upper arms 562a, 562b and the lower arms 564a, 564b may be flexible such that when the needle hub 518 is coupled to the needle carrier assembly 516, the upper arms 562a, 562b and the lower arms 564a, 564b fix the needle hub 518 in a desired orientation relative to the needle carrier assembly 516. For example, the upper arms 562a, 562b may be configured to bend radially inward such that when disposed through the carrier openings 568 in the needle carrier assembly 516, the upper arms 562a, 562b contact the upper surface of the needle carrier assembly 516 adjacent the carrier openings 568 and the lower arms 564a, 564b contact the lower surface of the needle carrier assembly 516 adjacent the carrier openings 568. Such an arrangement allows for a compliant fit between the needle carrier assembly 516 and the needle hub 518, and the lower arms 564a, 564b flex to allow the upper arms 562a, 562b to expand after clearing the surface of the carrier openings 568. The lower arms 564a, 564b may partially or fully relax to bias the needle hub distally, reducing the clearance between the needle hub and the needle carrier that would otherwise exist in a non-compliant fit. Additionally, the upper arms 562a, 562b and the lower arms 564a, 564b also serve to maintain contact between the base 566 and the top surface of the on-skin sensor assembly 508.

[0120] The base 566 includes an anti-rotation feature. The anti-rotation feature may include a key having a shape complementary to at least a portion of the sensor assembly opening 560 of the on-skin sensor assembly 508, and is configured to substantially prevent the needle hub 518 from rotating about an axis 567 parallel to the insertion element 520 with respect to the on-skin sensor assembly 508, for example, to prevent the base 566 from rotating within the sensor assembly opening 560. Additionally, or alternatively, the upper surface of the needle carrier assembly 516 adjacent to the carrier opening 568 may include a groove 570 configured to receive the upper arms 562a, 562b when the upper arms 562a, 562b are disposed through the carrier opening 568 in an orientation complementary to the orientation of the groove 570, thereby fixing the needle hub 518 with respect to the needle carrier assembly 516.

[0121] In some embodiments, the base 566 further includes a substantially flat surface that, in some cases, when the anti-rotation feature of the base 566 is engaged within the opening 560 of the on-skin sensor assembly 508, mates with the top or proximal surface of the on-skin sensor assembly 508 and is configured to maintain the insertion element 520 in a substantially perpendicular orientation with respect to the top surface of the on-skin sensor assembly 508.

[0122] Based at least in part on the above-described features of the needle hub 518, the on-skin sensor assembly 508, and / or the needle carrier assembly 516, the base 566 enables easy assembly during manufacturing, including but not limited to proper alignment and pre-assembly of the insertion element 520 onto the on-skin sensor assembly 508, and / or the ability to easily engage the assembly of the needle hub 518, the insertion element 520, the sensor, and the on-skin sensor assembly 508 with other portions of the assembled applicator 500.

[0123] Figures 20A and 20B illustrate perspective views of locking features for insertion elements in the form of needles 600a, 600b for use in an applicator for an analyte sensor system, according to some embodiments. For example, the needle 600a of FIG. 20 includes a locking feature including a ridge 602 configured to engage complementary shape features within the needle hub 518. As an alternative, the needle 600b of FIG. 20B includes a locking feature including a groove 604 configured to engage complementary shape features within the needle hub 518.

[0124] In yet another alternative, any insertion element described in the present disclosure may include a locking feature, such as, for example, a locking feature that heat-seals a selected insertion element to the needle hub 518. In yet another alternative, any insertion element described in the present disclosure may include a locking feature including one or more friction fit elements or snap fit elements that secure a selected insertion element to the needle hub 518. In yet another alternative, any insertion element described in the present disclosure may include a locking feature including complementary clam shell elements on a selected insertion element and the needle hub 518 configured to engage with each other. In yet another alternative, any insertion element described in the present disclosure may include a locking feature including one or more insert molding elements configured to connect a selected insertion element to the needle hub 518.

[0125] During manufacturing, the applicator 500 may be assembled in stages. For example, but not limited to, if present, the first barrier layer 512 may be attached to the inner housing 506. The insertion element 520 may be connected to the needle hub 518 and then it may be connected to the on-skin sensor assembly 508. The second spring 526 may be installed in the holder 522 or the needle carrier assembly 516 and then the needle carrier assembly 516 may be disposed in the holder 522 and attached to the needle hub 518 and the on-skin sensor assembly 508 via the wearable retention elements 534a, 534b. The first spring 524 may be disposed in the holder 522 and then installed in the inner housing 506. The inner housing 506 may be inserted into and fixed to the outer housing 504. If present, the second barrier layer 530 may be attached to the inner housing 506. If a separate element, the actuating element 502 may be disposed within the outer housing 504. Then, any labeling, sterilization, and / or packaging may be applied to the applicator 500.

[0126] Figures 21-23 illustrate some cross-sectional views of yet another applicator 700 for an on-skin sensor assembly of an analyte sensor system, as well as various features and operating positions, according to some embodiments.

[0127] The applicator 700 may include an outer applicator housing 504 that houses the actuating element 502. The outer applicator housing 504 may be configured to move linearly in the distal direction under the force applied by the recipient of the applicator 700, thereby aligning the actuating element 502 in a position that enables the applicator 700 to fire, which is the alignment illustrated by FIG. 21. As previously described in connection with the applicator 500, in some embodiments, the actuating element 502 may be disposed anywhere, such as at the top, upper, lower, or any other location of the applicator 700.

[0128] Applicator 700 further includes an inner housing 506 configured to house one or more mechanisms for applying the skin sensor assembly 508 to a recipient's skin. The distal surface 510 of the bottom opening of the inner housing 506 can define the bottom surface of the applicator 700. In some embodiments, when the applicator 700 is pressed against the recipient's skin, the skin can deform substantially convexly at the distal surface 510 such that at least a portion of the surface of the skin disposed at the bottom opening of the inner housing 506 extends proximally into the bottom opening of the inner housing 506 beyond the plane defined by the distal surface 510.

[0129] Although not illustrated in FIGS. 21 - 23, the inner housing 506 can include a spring 536 configured to contact the outer housing 504 and maintain a predetermined spacing therebetween in the pre - operative orientation (see FIG. 7). The spring 536 can be a compression spring, a leaf spring, a flexure arm spring, a foam, or a rubber piece, among others. In some other embodiments, the outer housing 504 can include a spring 536, and the spring 536 can be configured to contact the inner housing 506.

[0130] The applicator 700 may further include a needle carrier assembly 702. The needle carrier assembly 702 includes wearable retention and / or alignment elements 534a, 534b that pass through the holder 704 and are configured to releasably couple the skin sensor assembly 508 to the holder 704 and / or the needle carrier assembly 702. Although two wearable retention and / or alignment elements are illustrated, any number of wearable retention and / or alignment elements are contemplated.

[0131] The applicator 700 further includes a needle hub 518 configured to couple the insertion element 520 to the needle carrier assembly 702. The insertion element 520 is configured to insert the sensor of the on-skin sensor assembly 508 into the recipient's skin. In some embodiments, the insertion element 520 includes a needle, e.g., a side-opening needle, a needle with tip deflection, a curved needle, a polymer-coated needle, a hypodermic needle, or any other suitable type of needle or structure. In yet other embodiments, the insertion element 520 can be integrally formed with the sensor, and the insertion element 520 can be sufficiently rigid to be partially inserted into the recipient's skin with minimal structural support or without structural support.

[0132] The applicator 700 may further include a holder 704 releasably coupled to the needle carrier assembly 702, and the holder 704 is configured to guide the on-skin sensor assembly 508 while coupled to the needle carrier assembly 702, e.g., during linear movement from at least a proximal position to a distal insertion position. As previously described in connection with the applicator 500, when the on-skin sensor assembly 508 is disposed on the recipient's skin, the on-skin sensor assembly 508 may be removed or released from the holder 704 and / or the needle carrier assembly 702.

[0133] The applicator 700 may further include an insertion assembly configured to translate the insertion element 520, the needle hub 518, and the needle carrier assembly 702 from a proximal position to a distal insertion position in a distal direction. Such an insertion assembly may include a first spring 524. The first spring 524 may be a compression spring or any suitable type of spring, and may have a first end thereof in contact or connection with the inner applicator housing 506 and a second end thereof in contact or connection with the holder 704. The first spring 524 is configured to translate the holder 704, the needle carrier assembly 702, the needle hub 518, the insertion element 520, and the on-skin sensor assembly 508 in a distal direction to the distal insertion position during operation of the insertion assembly. At substantially the distal insertion position, the needle carrier assembly 702 may be separated from the holder 704 and the on-skin sensor assembly 508.

[0134] The applicator 700 may further include a retraction assembly configured to translate the needle carrier assembly 702, the needle hub 518, and the insertion element 520 proximally from a distal insertion position to a proximal retracted position. In some embodiments, the initial proximal position may be the same as the proximal retracted position. In other embodiments, the initial proximal position may be different from the proximal retracted position. Such a retraction assembly may include a second spring 706. The second spring 706 may be a compression spring or any suitable type of spring, and has a first end that contacts or is coupled to the holder 704, and a tongue 708 (e.g., a spring portion or a spring end) disposed substantially along the diameter of the second spring 706 and contacting or being coupled to the spring retaining element 710 of the holder 704 at least until retraction, and a second end. The spring retaining element 710 may include, for example, an arm, a flexing element, a tab, a detent, a snap, or any other feature capable of a retaining function. The spring retaining element 710 may have substantially the same form and function as the spring retaining elements 528a, 528b of the applicator 500, except as described below. The second spring 706 is configured to translate the needle carrier assembly 702, the needle hub 518, and the insertion element 520 proximally from a distal insertion position to a proximal retracted position. The tongue 708 of the second spring 706 is released from the spring retaining element 710 at the distal insertion position in response to the spring retaining element 710 not being backed up by the backstop element 712 and the tongue 708 of the second spring 706 pushing the spring retaining element 710 with a force exceeding a predetermined threshold sufficient to overcome and flex the spring retaining element 710.

[0135] The needle carrier assembly 702 further includes a backstop feature 712 that is configured to prevent lateral movement of the spring retaining element 710 of the holder 704, at least in an initial proximal operating position, thereby supporting the retention of the second spring 706 between the spring retaining element 710 and the holder 704 until retraction. In the orientation shown in FIG. 21, the second spring 706 exerts a force on the spring retaining element 710, but the backstop feature 712 prevents lateral flexing of the retaining element 710.

[0136] The holder 704 further includes a needle carrier retaining element 542 that can include a flexible arm, a rigid arm, a deformable feature, a snap, a catch, or a hook. When the needle carrier assembly 702 reaches the proximal retracted position after actuation, the needle carrier retaining element 542 is configured to engage the needle carrier assembly 702, thereby maintaining the needle carrier assembly 702, the needle hub 518, and the insertion element 520 in a locked retracted position and restricting access to the insertion element 520.

[0137] Although not illustrated in FIGS. 21-23, the inner housing 506 of the applicator 700 can further include an engagement element 550, the needle carrier assembly 702 can further include a protrusion 552, and can function substantially as previously described in connection with FIGS. 10-12.

[0138] Although not illustrated in FIGS. 21-23, the inner housing 506 of the applicator 700 can further include a protrusion extending distally from the inner housing 506, substantially like the protrusion 548 previously described. Similar to that previously described in connection with FIG. 13, this protrusion can be configured to contact at least one of the spring retaining element 710 and the backstop feature 712 in the pre-actuation state, such that the spring retaining element 710 is prevented from flexing laterally until the holder 704 and the needle carrier assembly 702 translate distally by at least a predetermined minimum distance. Thus, the protrusion can provide a means of drop protection so that the applicator 700 does not fire prematurely in response to a jolting shock caused by dropping prior to intentional actuation.

[0139] Instead of utilizing spring retaining elements 528a, 528b that are disposed along the outside of the second coil of spring 526 and configured to contact and hold the coils of second spring 526, applicator 700 utilizes spring retaining element 710 that is disposed along the inside of second spring 706 and configured to contact and hold tang 708 of second spring 706 along its diameter. Applicator 700 functions substantially the same as applicator 500, except that spring retaining element 710 is disposed substantially along and within the center of second spring 706 rather than along the outside of second spring 706. This further ensures that spring retaining element 710 does not contact the coils of second spring 706 when second spring 706 extends during retraction, thereby smoothing the operation of applicator 700. Additionally, the arrangement including spring retaining element 710, as opposed to spring retaining elements 528a, 528b, reduces the risk and difficulty of ensuring that multiple spring retaining elements are triggered or overcome substantially simultaneously.

[0140] Figure 21 illustrates the state of applicator 700 prior to actuation, according to some embodiments. Holder 704, needle carrier assembly 702, needle hub 518, insertion element 520, on-skin sensor assembly 508, first spring 524, and second spring 526 are all shown in their pre-actuation positions.

[0141] Retaining element 532 of holder 704 is in contact with inner housing 506, thereby fixing holder 704 and, thus, also fixing needle carrier assembly 702, needle hub 518, insertion element 520, and on-skin sensor assembly 508 in their pre-actuation states.

[0142] Backstop feature 712 of needle carrier assembly 702 contacts spring retaining element 710 to prevent spring retaining element 710 from flexing laterally, thereby ensuring that spring retaining element 710 holds tang 708 of second spring 706 in the shown loaded or pre-actuation position.

[0143] As shown in FIG. 21, the operation of applicator 700 may include the recipient pressing applicator 700 against his or her skin with sufficient force to linearly move outer housing 504 toward and distally with respect to inner housing 506 until actuating element 502 is aligned with insertion assembly retaining element 532 of holder 704. Once such alignment is achieved, the recipient may initiate actuating element 502, thereby sufficiently deflecting insertion assembly retaining element 532 to release holder 704 from inner housing 506. In some other embodiments, applicator 700 may be configured such that actuating element 502 may be actuated first, but actual insertion is not triggered until outer housing 504 is sufficiently linearly moved toward and distally with respect to inner housing 506. In still other embodiments, actuating element 502 may be biased toward the center of applicator 700 such that it need not be explicitly actuated by the recipient, but instead, actuating element 502 may be configured to automatically initiate insertion when outer housing 504 is sufficiently linearly moved toward and distally with respect to inner housing 506.

[0144] FIG. 22 illustrates applicator 700 during operation and insertion, according to some embodiments. First spring 524 drives holder 704 and thus drives needle carrier assembly 702, needle hub 518, insertion element 520, and on-skin sensor assembly 508 distally toward the distal insertion position. FIG. 22 illustrates on-skin sensor assembly 508 in contact with the recipient's skin, but holder 704 not yet fully driven into contact with on-skin sensor assembly 508 or the recipient's skin by first spring 524.

[0145] In some embodiments, the mass of each of the holder 704, the needle carrier assembly 702, the needle hub 518, the insertion element 520, and the on-skin sensor assembly 508 can be specifically designed to reduce or substantially eliminate the tendency for the needle carrier assembly 702, the needle hub 518, the insertion element 520, and the on-skin sensor assembly 508 to be removed from the holder 704 while being driven distally during insertion. In some embodiments, the force exerted by the first spring 524 can be further selected to be sufficient for proper operation of the applicator 700, but not so large as to further exacerbate the removal triggered by such inertia as described above. In some embodiments, a spring (not shown) can be configured to exert a force sufficient to prevent the needle carrier assembly 702 from being removed by inertial triggering from the holder 704 during insertion, against a portion of the needle carrier assembly 702, for example, in a distal direction.

[0146] FIG. 23 illustrates the applicator 700 after actuation and in or near the distal insertion position. The first spring 524 drives the holder 704, the needle carrier assembly 702, and the on-skin sensor assembly 508 distally to the distal insertion position. Since the first spring 524 drives the holder 704 distally a shorter distance than the needle carrier assembly 702, the backstop feature 712 no longer contacts the spring retaining element 710, allowing the second spring 706 (e.g., tongue 708) to deflect the spring retaining element 710 laterally, thereby releasing the second spring 706 and driving the needle carrier assembly 702 proximally. Alternatively, similar to that described above in connection with the applicator 500 of FIG. 13 where the angle θ of a portion of the spring retaining element 710 that contacts the tongue 708 of the second spring 706 is substantially 90° (e.g., flat), the spring retaining element 710 can be biased to automatically deflect just enough to release the second spring 706 when the backstop feature 712 no longer contacts the spring retaining element 710, thereby releasing the second spring 706 and driving the needle carrier assembly 702 proximally. Although not shown in FIGS. 21 - 23, the inner housing 506 can further include an engagement element 550 configured to engage the protrusion 552 of the needle carrier assembly 702 and function substantially as previously described in connection with FIGS. 10 - 12. In some embodiments, a stop feature (not shown) can be disposed at the bottom of the applicator 700, e.g., on the distal portion of the inner housing 506. Such a stop feature can be configured to contact one or more of the on-skin sensor assembly 508, the needle carrier assembly 702, or the holder 704 at the distal insertion position.

[0147] When the second spring 706 is released, the second spring 706 is configured to drive the needle carrier assembly 702, the needle hub 518, and the insertion element 520 in the proximal direction. Although not shown in FIG. 23, when the needle carrier assembly 702 moves to the proximal retracted position, the needle carrier retaining element 542 can engage the needle carrier assembly 702, thereby holding the needle carrier assembly 702, the needle hub 518, and the insertion element 520 in a locked retracted position that restricts access to the insertion element 520.

[0148] FIG. 24 illustrates a perspective view of the applicator 700's holder 704, the first spring 524, and the second spring 706 according to some embodiments. FIG. 24 illustrates the spring retaining element 710 and the retaining tang 708 of the second spring 706 in the orientation within the applicator 700 prior to retraction.

[0149] During manufacture, the applicator 700 can be assembled step by step. For example, but not limited to, if present, as previously described in connection with the applicator 500, the first barrier layer 512 (see FIG. 6) may be attached to the inner housing 506. The insertion element 520 may be connected to the needle hub 518 and then it may be connected to the on-skin sensor assembly 508. The second spring may be installed in the holder 704 or the needle carrier assembly 702, and then the needle carrier assembly 702 may be disposed within the holder 704 and attached to the needle hub 518 and the on-skin sensor assembly via the wearable retaining elements 534a, 534b. The first spring 524 may be disposed within the holder 704 and then installed within the inner housing 506. The inner housing 506 may be inserted into and fixed to the outer housing 504. If present, as previously described in connection with the applicator 500, the second barrier layer 530 (see FIG. 6) may be attached to the inner housing 506. If a separate element, the actuating element 502 may be disposed within the outer housing 504. Then any labeling, sterilization, and / or packaging may be applied to the applicator 700.

[0150] In an embodiment, the applicator system may include a cap and / or liner removal component. FIG. 25 illustrates, for example, an embodiment of an applicator 900 having an applicator housing 902 configured to hold a wearable medical device on the skin and a deployment mechanism configured to deploy the wearable medical device on the skin. The applicator housing 902 may be configured in a similar manner to embodiments of the applicators disclosed herein, including having an outer housing 904 and an inner housing 906 as disclosed with respect to the embodiments of FIGS. 5-24. The outer housing 904 may be configured similarly to, for example, the outer housing 504, and the inner housing may be configured similarly to the inner housing 506. The applicator housing 902 may be configured to be gripped by a user in an embodiment. Various other configurations of the applicator housing may be utilized as desired.

[0151] The applicator housing 902 may include an internal cavity 903 for holding a wearable medical device on the skin. The housing 902 can include an opening 905 at an end portion 907 of the internal cavity 903 for deploying the wearable medical device on the skin therefrom. The internal cavity 903 may include a proximal end portion 909 that may contain a wearable medical device on the skin coupled to a needle carrier assembly.

[0152] The deployment mechanism may be configured in the same manner as other forms of the deployment mechanism disclosed herein. The deployment mechanism may be configured in the same manner as the deployment mechanism disclosed with respect to the embodiments of FIGS. 5-24. For example, in an embodiment, the deployment mechanism may include one or more retention elements for holding a skin-wearable medical device and releasing the skin-wearable medical device from the housing 902 to the skin. The deployment mechanism can include an insertion assembly for inserting at least a portion of the skin-wearable medical device into the skin. The insertion assembly may insert an insertion element (e.g., a needle) into the skin. The deployment mechanism may drive the insertion element into the skin when the deployment mechanism deploys the skin-wearable medical device onto the skin. The deployment mechanism may include a retraction assembly for retracting the insertion element from the skin. Optionally, other forms of deployment mechanisms may be utilized in an embodiment.

[0153] The applicator 900 may include an operating element 908 that may operate in the same manner as the operating element 502. The applicator 900 may include a needle carrier assembly 910 that may operate in the same manner as the needle carrier assembly 516. The applicator 900 may include a holder 912 that may operate in the same manner as the holder 522. The applicator 900 may include a hub (e.g., needle hub 914) that may operate in the same manner as the needle hub 518. The applicator 900 may include an insertion element 915 (e.g., a needle) that may operate in the same manner as the insertion element 520. The applicator 900 may include springs 916, 918 that may operate in the same manner as springs 524, 526, respectively. The applicator 900 may include retention elements 920a, 920b that may operate in the same manner as retention elements 534a, 534b, respectively. Additional components of the applicator shown in FIGS. 5-24 may be utilized with the applicator 900. The applicator 900 may operate in a similar manner and provide similar functions as the applicators shown in FIGS. 5-24.

[0154] The applicator 900 may include a cap 942 that can be positioned at the distal portion of the applicator housing 902 and can cover the distal opening 905 of the internal cavity 903. The cap 942 may include a gripping portion 944 on the outer surface of the cap 942 and an engaging portion 946 on the inner surface of the cap 942. The cap 942 may include a central portion 948 that covers and spans the distal opening 905 of the internal cavity. The cap 942 may include an outer lid for the applicator 900 during transportation and unpacking of the applicator 900.

[0155] The central portion 948 of the cap 942 may include one or more openings 950 that may allow a sterilizing substance, such as a sterilizing gas, to pass through to sterilize the internal components of the applicator 900. The central portion 948 may include a central support 952 that may be configured to press against the liner removal component 928 to hold the liner removal component 928 in place. The central support 952 may be configured to rotate when disconnecting or unscrewing the cap 942 from the applicator housing 902.

[0156] The engaging portion 946 may include a thread or another form of engaging portion 946 for engaging a corresponding engaging portion 954 on the outer surface of the housing 902. The engaging portion 946 may be configured to be rotated relative to the applicator housing 902 to unscrew from the housing 902 and allow release of the liner removal component 928 from the applicator housing 902.

[0157] The applicator 900 may include a liner removal component 928. The liner removal component 928 may engage a liner 926 positioned on the engagement surface of the patch 922 and may be configured to remove the liner 926 from the engagement surface of the wearable medical device on the skin when pulled out from the engagement surface of the wearable medical device on the skin. The liner removal component 928 may include an engagement surface 930 for engaging the liner 926. The engagement surface 930 may be a flat surface that may extend parallel to the liner 926. The engagement surface 930 may include an opening 927 configured to allow the insertion element 915 to pass through. The liner removal component 928 may further include a sheath 939 configured to cover the insertion element 915. The liner removal component 928 may further include a raised portion 936 that may extend from the distal portion 932 of the liner removal component 928. The raised portion 936 may extend axially within the internal cavity 903.

[0158] The distal portion 932 of the liner removal component 928 may include a flange 933 for gripping by the user to remove the liner removal component 928 from the internal cavity 903 and thus remove the liner 926 from the engagement surface of the wearable medical device on the skin. In an example, the flange 933 may be excluded from use.

[0159] In an example, the liner 926 may be positioned on the engagement surface of the patch. The liner may cover the engagement surface and protect the engagement surface from damage, degradation, or other adverse effects. The liner may include, for example, a sheet of material that covers the engagement surface of the patch. The liner may have a proximal surface that contacts the engagement surface of the patch and a distal surface that faces opposite the proximal surface. The liner in an example may be configured to reduce the likelihood that the exposed engagement surface degrades or otherwise loses its adhesive properties prior to deployment. For example, during a sterilization process using a gas or other sterilizing material, the liner may reduce the likelihood that the engagement surface degrades. The sterilizing gas may include ethylene oxide (EtO) or another desired form of sterilizing gas. However, the liner should be removed from the engagement surface before the skin sensor assembly is deployed on the skin.

[0160] Applicator 900 may be utilized to deploy a skin-worn wearable medical device onto the skin. The skin-worn wearable medical device may comprise, for example, a skin sensor assembly 508 as shown in FIG. 6, and the skin sensor assembly 508 may include a housing, an analyte sensor coupled to the housing, an electronics unit, and a patch 922. The skin sensor assembly may have a form as shown in FIGS. 2A-4, or other forms as desired.

[0161] Cap 942 and liner removal component 928 may be removed prior to deployment of the skin-worn wearable medical device onto the skin.

[0162] When actuated, the applicator disclosed herein may insert a transcutaneous analyte sensor into the skin of a recipient by utilizing an insertion element (such as insertion element 915).

[0163] Referring to FIG. 26A, insertion element 915 may drive analyte sensor 956 of skin sensor assembly 508 into the skin of a recipient by means of an analyte sensor 956 extending along channel 958 of insertion element 915.

[0164] Analyte sensor 956 may include, for example, a first portion 960 or contact portion that may be coupled to housing 962 of skin sensor assembly 508. The first portion 960 may include, for example, an electrical contact 964 that may be electrically connected to an electrical terminal of skin sensor assembly 508 or another component of skin sensor assembly 508. The electrical terminal may be positioned on an interface substrate or a circuit board, or another component of skin sensor assembly 508 as desired. Other methods of coupling between the first portion 960 and the housing 962 may be utilized as desired.

[0165] The analyte sensor 956 may include a second portion 966 that includes a sensing portion and may be configured to be inserted into or through the recipient's skin and positioned within or beneath the skin. In an embodiment, the second portion 966 may extend distally from the distal surface 968 of the housing 962 and may be guided into the recipient's skin by the insertion element 915. The second portion 966 may be linear and may be axially aligned with an opening 978 for the insertion element 915 to pass through, as shown in FIG. 26A.

[0166] The analyte sensor 956 may include an elongated analyte sensor. The second portion 966 may extend distally to be positioned within the recipient's skin layer. In an embodiment, the second portion 966 of the analyte sensor 956 may extend perpendicular to the distal surface 968 of the housing 962. In other embodiments, other angles may be utilized as desired. The second portion 966 may extend perpendicular to the first portion 960 of the analyte sensor 956. In other embodiments, other angles may be utilized as desired.

[0167] The bend 970 may angle the second portion 966 of the analyte sensor 956 with respect to the first portion 960 of the analyte sensor 956. The bend 970 may be positioned, for example, between the second portion 966 and the first portion 960, may have a continuous curvature, as shown in FIG. 26A, or may have another configuration as desired. The bend 970 may angle the second portion 966 at a perpendicular angle or another angle as desired with respect to the first portion 960. The bend 970 may be axially aligned with an opening 978 for the insertion element 915 to pass through, as shown in FIG. 26A. Other configurations of the analyte sensor 956 may be utilized as desired.

[0168] The housing 962 of the sensor assembly 508 on the skin can be configured similarly to the other forms of housing disclosed herein. The housing 962 can be configured to be worn on the skin of the recipient. The housing 962 can include a distal surface 968 configured to face the skin of the recipient. The patch 922 can be positioned on the distal surface 968 of the housing 962. The patch 922 can include an engagement surface 974 for engaging the skin of the recipient. The engagement surface 974 can include, in an example, an adhesive surface or another form of surface.

[0169] The housing 962 can include a proximal surface 972 facing opposite the distal surface 968. The proximal surface 972 can extend parallel to the distal surface 968 or can have another configuration as desired.

[0170] The housing 962 can include, in an example, a cavity 976 configured to receive a first portion 960 of the analyte sensor 956. The cavity 976 can have various forms as desired. For example, the cavity 976 can be configured to hold an adhesive (which can include a liquid adhesive or a curable adhesive) that can connect the first portion 960 of the analyte sensor 956 to the housing 962 in an example. The cavity 976 can hold the adhesive and can include one or more dams or other features that can be utilized to electrically insulate portions of the analyte sensor 956 from each other if desired. In an example, the cavity 976 can include a recess for the first portion 960 of the analyte sensor 956 to be inserted into and otherwise connected to the housing 962. In an example, the use of the cavity 976 can be excluded and the first portion 960 of the analyte sensor 956 can be otherwise connected to the housing 962.

[0171] The housing 962 may include an opening 978 for the insertion element 915 to pass through. The opening 978 may extend through the proximal surface 972 of the housing 962 and may extend to the distal surface 968 of the housing 962. The opening 978 may be configured to allow the insertion element 915 to retract proximally therethrough from the skin. The insertion element 915 may be retracted after piercing the recipient's skin. In an embodiment, the insertion element 915 may be positioned within the opening 978 upon insertion into the recipient's skin or may be passed distally relative to the opening 978 upon insertion into the recipient's skin. In an embodiment as shown in FIG. 26A, the insertion element 915 may be positioned within the opening 978 and may be static relative to the opening 978 upon insertion into the recipient's skin. For example, as shown in FIGS. 7, 8, and 21 - 23, the insertion element 915 may move distally with the housing 962 of the skin-on sensor assembly 508 and may remain stationary relative to the housing 962 upon insertion into the recipient's skin. Other forms of insertion may be utilized in embodiments.

[0172] The insertion element 915 may include a proximal end portion 980 and a distal end portion 982 having a tip 984 of the insertion element 915. The tip 984 may, in an embodiment, include a sharp tip and may be configured to pierce the recipient's skin and be inserted into the recipient's skin.

[0173] The needle hub 914 may be positioned on the proximal end portion 980 of the insertion element 915. The needle hub 914 may contact the proximal surface 972 of the housing 962 and may be spaced from the proximal surface 972 as desired.

[0174] The insertion element 915 may include an elongated insertion element 915 and may include a shaft 986 that may extend between a proximal end portion 980 and a distal end portion 982. The shaft 986 may be straight or may have a linear shape and may be configured to guide the analyte sensor 956 into the recipient's skin. For example, the shaft 986 may have a channel 958 that may receive the analyte sensor 956. Referring to FIG. 28, the shaft 986 has an opening 987 for a channel 958 that is configured such that the analyte sensor 956 is positioned therein. A portion of the analyte sensor 956 (e.g., the second portion 966 or the sensing portion) may be positioned within the channel 958 and may be bounded by the sidewall 988 of the insertion element 915 (marked in FIG. 28). The sidewall 988 may be positioned on the side of the channel 958. The shaft 986 may extend along a portion of the analyte sensor 956 (e.g., the second portion 966 or the sensing portion). In an embodiment, the shaft 986 may extend parallel along a portion. Thus, the second portion 966 including the sensing portion of the analyte sensor 956 may extend along the shaft 986.

[0175] The analyte sensor 956 may be positioned within the channel 958 such that when the insertion element 915 is inserted into the recipient's skin, the analyte sensor 956 is inserted together with the insertion element 915 and guided into the recipient's skin. The shaft 986 may be inserted into the skin to guide a portion (e.g., the second portion 966 or the sensing portion) into the skin. The channel 958 may form a space for the insertion of the analyte sensor 956 within the recipient's skin. When the insertion element 915 is retracted, the analyte sensor 956 may remain within the recipient's skin. In an embodiment, other forms of insertion may be provided. For example, in an embodiment, the insertion element 915 may lack the channel 958, and the analyte sensor 956 may extend along the outer surface of the insertion element 915 for insertion into the recipient's skin.

[0176] The channel 958 may have a C-shaped cross-section in an embodiment (e.g., FIG. 28) or may have another cross-section as desired.

[0177] FIG. 26B illustrates an insertion element 915 withdrawn by an applicator retraction assembly or by another means. The analyte sensor 956 can remain positioned within the recipient's skin and can continuously sense the recipient's analyte over several days.

[0178] As used throughout this specification, unless otherwise specified, the term friction can include kinetic friction between the insertion element 915 and the analyte sensor 956 and / or can include static or stiction friction. Friction can exist between the insertion element 915 and the analyte sensor 956, which can be beneficial. After the analyte sensor 956 is positioned within the channel 958 during manufacture, the friction between the insertion element 915 and the analyte sensor 956 helps to maintain the positioning of the analyte sensor 956 therein and can reduce the likelihood that the analyte sensor 956 undesirably exits the channel 958 during transport and / or handling prior to insertion. During insertion, the friction can also advantageously maintain the position of the analyte sensor 956 within the channel 958 as the insertion element 915 pierces and guides the analyte sensor 956 into the recipient's skin.

[0179] Friction can exist between the insertion element 915 and the analyte sensor 956, which can produce adverse results. Referring to FIG. 27A, for example, the analyte sensor 956 can be positioned within the channel of the insertion element 915 before and during insertion into the recipient's skin. If the level of friction present between the analyte sensor 956 and the insertion element 915 is too high, when the insertion element 915 is retracted (as shown in FIG. 27B), the analyte sensor 956 can also be retracted proximally. In particular, if the level of static friction present between the analyte sensor 956 and the insertion element 915 is too high, when the insertion element 915 is retracted (as shown in FIG. 27B), the analyte sensor 956 can also be retracted proximally. The analyte sensor 956 can retract proximally such that it may be completely withdrawn from the recipient's skin or may be partially withdrawn from the recipient's skin. Retraction of the analyte sensor 956 can, due to mispositioning of the analyte sensor 956, reduce the ability of the analyte sensor 956 to properly sense an analyte within the recipient's body or can result in complete withdrawal of the analyte sensor 956 from the recipient's skin. Further, a bend 990, which may include a "U" bend, can be formed within the analyte sensor 956 when the insertion element 915 is retracted. Formation of the bend 990 can interfere with the electrical signal provided by the analyte sensor 956 to the electronics of the skin sensor assembly 508 and may be undesirable.

[0180] In an embodiment, the analyte sensor 956 can retract along the opening 978 of the housing 962 as the insertion element 915 retracts along the opening 978. In an embodiment, the analyte sensor 956 can retract so as to protrude from the proximal surface 972 of the housing 962, as shown in FIG. 27B, or alternatively can retract in an undesirable manner without protruding from the proximal surface 972.

[0181] Retraction of the analyte sensor 956 can be caused by friction (e.g., kinetic or static friction) between the analyte sensor 956 and the inner surface 992 of the insertion element 915 (marked in FIG. 28). It has been observed that the static friction between the analyte sensor 956 and the inner surface 992 tends to be greater than the kinetic friction that occurs when the insertion element 915 is retracted. Thus, in many situations, whether the analyte sensor 956 retracts with the insertion element 915 is determined by the level of static friction between the analyte sensor 956 and the inner surface 992. The inner surface 992 can include the inner surface of the insertion element 915 that defines the channel 958. In other configurations (e.g., where the insertion element 915 does not include a channel), the inner surface 992 can include the outer surface of the insertion element or another surface as desired. The inner surface 992 can, in an embodiment, have friction with the outer surface 994 or another surface of the analyte sensor 956.

[0182] An undesirable level of friction between the analyte sensor 956 and the insertion element 915 can be generated or increased in the sterilization process applied to the analyte sensor 956 and / or the insertion element 915 and / or other components of the on-skin sensor assembly or applicator. For example, the sterilization process can include heat applied to such components. The sterilization process can include increased humidity applied to such components. The sterilization process can include a sterilizing gas (e.g., ethylene oxide (EtO), or another form of sterilizing gas) applied to such components. In an embodiment, a combination of sterilization methods can be utilized in the sterilization process. For example, a sterilization process using ethylene oxide (EtO) can include applying heat, humidity, and EtO to the analyte sensor 956 and the insertion element 915 over a certain duration.

[0183] The sterilization process may include applying heat, humidity, and EtO to the applicator 900 having the analyte sensor 956 and the insertion element 915 positioned within the applicator housing 902. Heat, humidity, and EtO may pass through, for example, the opening 950 shown in FIG. 25 and / or through a barrier layer covering the opening 950. The barrier layer may be moisture and / or gas permeable such that humidity and EtO are enabled to contact the analyte sensor 956 and the insertion element 915. Other components of the applicator 900 may be sterilized. Other forms of sterilizing gas and other sterilization methods may be utilized.

[0184] The analyte sensor 956 may be positioned within the channel 958 of the insertion element 915 during the sterilization process. For example, the analyte sensor 956 and the insertion element 915 may be in a position as shown in FIGS. 27A and / or 28 during the sterilization process. In embodiments, other configurations of the analyte sensor 956 and the insertion element 915 may be utilized as desired.

[0185] The sterilization process applied to the analyte sensor 956 and / or the insertion element 915 may increase the friction between the analyte sensor 956 and the insertion element 915. For example, the static friction between the analyte sensor 956 and the insertion element 915 may be increased during the sterilization process. Heat and humidity may, for example, swell the membrane of the analyte sensor 956 that may create an adhesion between the analyte sensor 956 and the insertion element 915. An adhesive may remain after a drying cycle applied to the analyte sensor 956 and the insertion element 915. Without being bound by any particular theory, the static friction may be caused by the hydration of a membrane that results in the formation of hydrogen bonds between the outer surface 994 of the analyte sensor 956 and the inner surface 992 of the insertion element 915 or by other forms of bonding between the analyte sensor 956 and the insertion element 915 that may result from charge, chemical interactions, and / or mechanical properties. For example, a sterilization process involving heat, humidity, and / or EtO may cause or increase the hydrogen bonds between the analyte sensor 956 and the insertion element 915. Other forms of bonding (regardless of being electrical, chemical, or mechanical) may be formed or increased as a result of the sterilization process.

[0186] An extended or amplified sterilization process can increase undesirable friction (e.g., static friction) and the likelihood of undesirable retraction of the analyte sensor 956 after insertion. The greater the surface area in contact with the insertion element 915, and the greater the film sensitivity of the analyte sensor 956 to heat and humidity during the sterilization process, the greater the likelihood of undesirable friction and undesirable retraction of the analyte sensor 956 after insertion. A sterilization process with a reduced duration or reduced intensity (i.e., lower temperature and lower humidity) can reduce the friction and the likelihood of undesirable retraction of the analyte sensor 956 after insertion. A relatively small surface area contact with the insertion element 915 and a low film sensitivity of the analyte sensor 956 during the sterilization process can also reduce the likelihood of undesirable friction and undesirable retraction of the analyte sensor 956.

[0187] In an embodiment, an increased elastic modulus or stiffness of the analyte sensor 956 can reduce the likelihood of retraction of the analyte sensor 956 in order to resist the buckling force applied proximal to the analyte sensor 956. A relatively low modulus of elasticity or stiffness of the analyte sensor 956 can increase the likelihood of undesirable retraction of the analyte sensor 956.

[0188] In an embodiment, an increase in the force of the retraction spring (e.g., the second spring 526) increases the instantaneous retraction acceleration of the insertion element 915 at the start of the retraction step. The force transmitted through the friction between the analyte sensor 956 and the insertion element 915 (i.e., the detachment static friction) is insufficient to accelerate the analyte sensor 956 at the same speed as the insertion element 915, considering the stiffness and inertial mass of the analyte sensor 956. Thus, the insertion element 915 retracts while the analyte sensor 956 remains inserted within the recipient's skin.

[0189] The systems, devices, and methods disclosed herein can be utilized after a sterilization process, but such systems, devices, and methods can be utilized in the absence of a sterilization process. For example, the systems, devices, and methods are not limited to those utilized after a sterilization process, or during or before a sterilization process.

[0190] The systems, devices, and methods disclosed herein can include providing a diametrical clearance 996 (marked in FIG. 28) from the shaft 986 of the insertion element 915 to the analyte sensor 956 (e.g., the second portion 966 or the sensing portion). The clearance 996 can reduce the likelihood of friction (e.g., kinetic or static friction) between the insertion element 915 and the analyte sensor 956. For example, after a sterilization process, the analyte sensor 956 can expand (e.g., the diameter can increase), and / or hydrogen bonds (or other forms of bonding) can form between the insertion element 915 and the analyte sensor 956. A diametrical clearance 996 above a threshold can reduce the likelihood of such undesirable friction.

[0191] The diametrical clearance 996 can be determined, in an example, before a sterilization process is applied to the analyte sensor 956 and / or the insertion element 915. The diametrical clearance 996 can be measured before the sterilization process, and if the clearance 996 is above the threshold, the analyte sensor 956 and / or the insertion element 915 can continue to be used in the sterilization process. In an example, the diametrical clearance 996 can be measured in the absence of the application of a sterilization process, or after the sterilization process. The analyte sensor 956 and / or the insertion element 915 can be utilized if the threshold diametrical clearance is met. The threshold diametrical clearance 996 can be set to reduce the likelihood of undesirable friction between the analyte sensor 956 and / or the insertion element 915.

[0192] In an embodiment, the diametrical clearance 996 can be set to at least 0.07 millimeters. This can be the distance before the sterilization process or the distance after the sterilization process. The diametrical clearance can be between the shaft 986 of the insertion element 915 and the analyte sensor 956 (e.g., the second portion 966 or the sensing portion). This distance can reduce the possibility of undesirable friction between the analyte sensor 956 and the insertion element 915. In an embodiment, the diametrical clearance 996 can be set to at least 0.10 millimeters. In an embodiment, the diametrical clearance 996 can be set to at least 0.12 millimeters. Other diametrical clearances can be utilized and set to reduce the undesirable friction between the analyte sensor 956 and the insertion element 915 and to reduce the frequency with which the analyte sensor 956 undesirably retracts during retraction of the insertion element 915.

[0193] In an embodiment, other features of the analyte sensor 956 and / or the insertion element 915 can be utilized or determined to reduce the possibility of undesirable retraction of the analyte sensor 956 during retraction of the insertion element 915. The ratio of the diameter 989 of the second portion (marked in FIG. 28) including the sensing portion of the analyte sensor 956 to the width 991 of the opening 987 for the channel 958 can be determined, for example, before the sterilization process or during or after the sterilization process. In an embodiment, if the ratio is determined to be below a threshold value, the analyte sensor 956 can continue to be used in the sterilization process. In an embodiment, the ratio can be measured when there is no application of the sterilization process or can be measured after the sterilization process. The analyte sensor 956 can be utilized if the threshold ratio is met.

[0194] In an embodiment, the ratio of the diameter 989 to the width 991 can be set to less than 0.9. This can be the ratio before the sterilization process or the ratio after the sterilization process. In an embodiment, the ratio can be set to less than 0.8. In an embodiment, the ratio can be set to less than 0.7. Other ratios can be utilized and set to reduce the possibility of the analyte sensor 956 retracting during retraction of the insertion element 915.

[0195] In an embodiment, other features of the analyte sensor 956 can be utilized or determined to reduce the likelihood of undesirable retraction of the analyte sensor 956 when the insertion element 915 is retracted. The flexural modulus of the analyte sensor 956 can be determined, for example, before, during, or after a sterilization process. An analyte sensor 956 having a greater flexural modulus can be less likely to retract during retraction of the insertion element 915. In an embodiment, if it is determined that the flexural modulus is above a threshold value, the analyte sensor 956 can continue to be used in a sterilization process. In an embodiment, the flexural modulus can be measured in the absence of the application of a sterilization process, or can be measured after a sterilization process. The analyte sensor 956 can be utilized if a threshold flexural modulus is met.

[0196] In an embodiment, the flexural modulus can be set to be greater than 8 gigapascals. This can be the flexural modulus before a sterilization process and can be the flexural modulus after a sterilization process. The flexural modulus can reduce the likelihood that the analyte sensor 956 will retract during retraction of the insertion element 915. In an embodiment, the flexural modulus can be set to be greater than 8.4 gigapascals. In an embodiment, the flexural modulus can be set to be greater than 8.6 gigapascals. Other modulus values can be utilized and set to reduce the likelihood that the analyte sensor 956 will retract during retraction of the insertion element 915. The flexural modulus can, in an embodiment, be of a second portion 966 that includes the sensing portion of the analyte sensor 956.

[0197] The configuration of the insertion element 915 and / or the analyte sensor 956 can be utilized alone or in combination with other systems, devices, and / or methods disclosed herein.

[0198] In an embodiment, the system, apparatus, and / or method can include reducing friction between the analyte sensor 956 and the insertion element 915, for example, via coating, lubrication, and surface roughness modification. In an embodiment, the friction can be reduced during or subsequent to a sterilization process performed on the analyte sensor 956 and the insertion element 915 and before retracting the insertion element 915 from the skin of the recipient. In an embodiment, the friction can be reduced prior to the sterilization process or at another time as desired.

[0199] In an embodiment, the friction between the analyte sensor 956 and the insertion element 915 can be reduced by vibrating the analyte sensor 956 and the insertion element 915. In an embodiment, during or subsequent to a sterilization process (e.g., an EtO sterilization process), the analyte sensor 956 and the insertion element 915 can be vibrated to reduce the friction (e.g., break static friction) between the analyte sensor 956 and the insertion element 915. The process can include sterilizing one or more applicators 900 (e.g., in the configuration shown in FIG. 25) and vibrating the applicator 900 to reduce friction. The plurality of applicators 900 can be sterilized, for example, on a surface such as a pallet, and the pallet as a whole or another surface can be vibrated to vibrate the analyte sensor 956 and the insertion element 915. In an embodiment, direct vibration to the analyte sensor 956 and / or the insertion element 915 can be provided. The method of direct vibration can include the methods disclosed herein or other methods of directly vibrating the analyte sensor 956 and / or the insertion element 915. In other embodiments, the vibration can occur prior to the sterilization process or in the absence of a sterilization process.

[0200] In an embodiment, the friction between the analyte sensor 956 and the insertion element 915 can be reduced by increasing or decreasing the ambient temperature. For example, during or following a sterilization process, the ambient temperature surrounding the analyte sensor 956 and the insertion element 915 can be reduced over a certain duration. The temperature can be reduced to a freezing temperature (e.g., 0 degrees Celsius (C), -18C, or -40C) in an embodiment, or to another temperature as desired. The temperature can be maintained at a reduced state for a certain duration (e.g., 24 hours, or 2 - 3 hours) as desired. In an embodiment, the temperature can be increased to a high temperature (e.g., 50C) for a certain duration (e.g., 24 hours, or 2 - 3 hours) as desired. The variation in temperature can cause a reduction in the overall friction (i.e., by breaking static friction) between the analyte sensor 956 and the insertion element 915 due to the difference in the coefficient of thermal expansion between the analyte sensor 956 and the insertion element 915, causing movement between them. In an embodiment, a combination of temperature increase and temperature decrease can reduce the friction between the analyte sensor 956 and the insertion element 915. For example, a cycle where a temperature decrease follows a temperature increase, or a temperature decrease precedes, can be utilized to reduce the friction between the analyte sensor 956 and the insertion element 915. The temperature increase can be provided for a certain duration (e.g., 24 hours, or 2 - 3 hours), followed or preceded by a duration of temperature decrease (e.g., 24 hours, or 2 - 3 hours). The temperature increase can alternate with the temperature decrease for a desired number of cycles. Thermal shocks of temperature increase and temperature decrease can be utilized in an embodiment. In other embodiments, the variation in temperature can occur before a sterilization process or in the absence of a sterilization process.

[0201] In an embodiment, the friction between the analyte sensor 956 and the insertion element 915 can be reduced by decreasing the ambient humidity. For example, during or following a sterilization process, the ambient humidity surrounding the analyte sensor 956 and the insertion element 915 can be decreased over a certain duration. The humidity can be decreased for a certain duration to reduce the moisture present within the membrane of the analyte sensor 956. The humidity can be decreased to dry the analyte sensor 956 and the insertion element 915, or the space between the analyte sensor 956 and the insertion element 915, and can cause the analyte sensor 956 to contract or deswell. The humidity can be decreased to create a dry ambient environment, and can be decreased along with an increase in temperature to create a hot, dry ambient environment. The environment can be created after a sterilization process. In other embodiments, variations in the ambient humidity can occur prior to a sterilization process or in the absence of a sterilization process.

[0202] The methods disclosed herein can occur with the skin sensor assembly (including the analyte sensor 956) and the insertion element positioned within the applicator housing, or can occur outside of the applicator housing.

[0203] In an embodiment, the desiccant 998 can be packaged with the analyte sensor 956 and / or the insertion element 915, or can otherwise be provided with the analyte sensor 956 and / or the insertion element 915. The desiccant 998 can reduce the moisture in the ambient environment surrounding the analyte sensor 956 and / or the insertion element 915, for example, to reduce the friction (e.g., static friction) between the analyte sensor 956 and the insertion element 915. In an embodiment, the desiccant 998 can be packaged or otherwise provided after or during a sterilization process. For example, the desiccant 998 can be inserted into a cavity, such as a cavity in the cap 942 as shown in FIG. 29, and the desiccant 998 is positioned to reduce moisture passing through the opening 950. Other positions of the desiccant 998 can be provided as desired.

[0204] The methods disclosed herein can reduce the hydrogen bonding between the analyte sensor 956 and the insertion element 915, or can otherwise reduce the friction (e.g., kinetic or static friction).

[0205] The methods disclosed in this specification can be used alone or in combination with any of the systems, devices, or other methods disclosed herein.

[0206] In an embodiment, the spacer body can be configured to be positioned between a portion of the elongated analyte sensor 956 and the insertion element 915, and can separate a portion of the elongated analyte sensor 956 from the insertion element 915. The spacer body can separate a portion of the elongated analyte sensor 956 (e.g., a second portion 966 including the sensing portion of the analyte sensor 956) from the shaft 986 of the insertion element 915.

[0207] FIG. 30A illustrates an embodiment in which the spacer body 1000 can comprise a thermally expandable body that can be positioned between the analyte sensor 956 and the insertion element 915. The spacer body 1000 can be positioned, for example, within the channel 958 between the analyte sensor 956 and the insertion element 915. The spacer body 1000 can be positioned on the inner surface 992 of the insertion element 915. The spacer body 1000 can be an elongated body that can extend along the longitudinal axis of the insertion element 915, or can have another form in an embodiment.

[0208] In an embodiment, the spacer body 1000 can comprise a thermally expandable metal. In an embodiment, the spacer body 1000 can comprise another form of thermally expandable material (e.g., a polymer or other form of material). The spacer body 1000 in an embodiment can have a second coefficient of thermal expansion that is different from the first coefficient of thermal expansion of the insertion element 915. The insertion element 915 can be configured to expand at a first rate in response to variations in temperature, and the spacer body 1000 can be configured to expand at a second rate that is different from the first rate. The second rate can be greater than the first rate to allow for greater expansion in response to variations in temperature.

[0209] Referring to FIG. 30A, the analyte sensor 956 can be separated from the insertion element 915 by a distance 1002. Such a distance 1002 can be before the thermal expansion of the spacer body 1000. In an example, the temperature of the spacer body 1000 can be varied. Such variations can include an increase in the temperature of the spacer body 1000 (which can include variations in the temperature of the insertion element 915). The temperature can be varied during (e.g., by applying heat) or after a sterilization process. For example, variations in temperature can occur during an EtO process, and the spacer body 1000 can expand during the temperature increase of the EtO process or after the EtO process. In other examples, the temperature can be varied before a sterilization process or in the absence of a sterilization process.

[0210] Variations in temperature can, as shown in FIG. 30B, increase the size of the spacer body 1000. The spacer body 1000 can expand towards the analyte sensor 956 and can push the analyte sensor 956 away from the inner surface 992 of the insertion element 915. Thus, the diametrical clearance of the insertion element 915 from the analyte sensor 956 can be increased.

[0211] The temperature can be further varied (e.g., decreased) to decrease the size of the spacer body 1000. For example, FIG. 30C illustrates a spacer body 1000 with a reduced size, but the analyte sensor 956 remains at an increased distance 1004 (greater than the distance 1002 shown in FIG. 30A). Thus, the increased distance can reduce the possible friction (e.g., kinetic or static friction) between the analyte sensor 956 and the insertion element 915 and can reduce the likelihood of an undesired retraction of the analyte sensor 956 upon retraction of the insertion element 915.

[0212] Other forms of spacer bodies can be utilized in examples.

[0213] For example, FIG. 31 illustrates an embodiment of a spacer body 1010 positioned between a portion of an elongate analyte sensor 956 and an insertion element 915 and configured to space the portion of the elongate analyte sensor 956 from the insertion element 915. The spacer body 1010 can be positioned to deflect the analyte sensor 956 away from the insertion element 915 so that the analyte sensor 956 is not initially positioned within the channel 958 of the insertion element 915. In an embodiment, the spacer body 1010 can space the analyte sensor 956 from the insertion element 915, and the analyte sensor 956 is positioned within the channel 958 but spaced from the insertion element 915 due to the presence of the spacer body 1010.

[0214] The spacer body 1010 can space the analyte sensor 956 from the insertion element 915 before, during, or after a sterilization process. Thus, in embodiments where the spacer body 1010 is positioned before or during a sterilization process, the spacer body 1010 can reduce the likelihood of friction (e.g., static friction) formed between the analyte sensor 956 and the insertion element 915 during such a sterilization process. For example, the distance between the analyte sensor 956 and the insertion element 915 can reduce the likelihood of hydrogen bonding or other forms of bonding that occur during a sterilization process. Thus, the analyte sensor 956 and the insertion element 915 can be sterilized in the configuration as shown in FIG. 31. In an embodiment, the spacer body 1010 can be inserted during the loading process of the analyte sensor 956 and the insertion element 915, and the insertion element 915 is inserted to extend along the analyte sensor 956, but the spacer body 1010 spaces the analyte sensor 956 from the insertion element 915.

[0215] The spacer body 1010 can have various forms and can include a bar as shown in FIGS. 31 and 32. The bar can include a crossbar 1012 (marked in FIG. 32), and the crossbar 1012 can include a larger diameter end portion 1014 that can prevent the crossbar 1012 from sliding laterally out of the analyte sensor 956.

[0216] The spacer body 1010 may be removable between a portion of the analyte sensor 956 and the insertion element 915 (e.g., the shaft 986 of the insertion element 915). The spacer body 1010 may be configured to be removed to seat a portion of the analyte sensor (e.g., the second portion 966 or the sensing portion) within the channel 958 (shown in FIG. 28).

[0217] In an embodiment, the spacer body 1010 may be manually removable between the analyte sensor 956 and the insertion element 915. For example, the spacer body 1010 may be coupled to a tether 1016 that is configured to be pulled to remove the spacer body 1010 between a portion of the analyte sensor 956 and the insertion element 915. The tether 1016 may be coupled to the crossbar 1012 or another portion of the spacer body 1010.

[0218] In an embodiment, the tether 1016 may comprise a pull tab for the user to pull. For example, prior to insertion of the insertion element 915 and the analyte sensor 956 into the recipient's skin, the tether 1016 may be pulled by the user. The spacer body 1010 may be removed to enable the analyte sensor 956 to seat within the channel 958 of the insertion element 915. The insertion element 915 may then be utilized to insert the analyte sensor 956 into the recipient's skin. By placing the analyte sensor 956 within the channel 958 of the insertion element 915 immediately prior to application by the user, any friction resulting from the sterilization process and / or increasing over time is eliminated. This advantage also applies to other embodiments where the analyte sensor 956 is separated from the channel 958 until immediately prior to application by the user.

[0219] In an embodiment, the tether 1016 can be covered by a cap, such as cap 942 shown in FIG. 25, in the form of a cover. Cap 942 can cover the distal surface of the housing of the sensor assembly on the skin. Cap 942 can be positioned in the distal opening of the applicator housing (as shown, for example, in FIG. 25). When removing cap 942, the tether 1016 can be accessible to a user who can pull on the tether 1016 to displace the tether 1016 from its position between the spacer body 1010 and the analyte sensor 956 and the insertion element 915.

[0220] The tether 1016 and the spacer body 1010 can be formed from a single piece of material, although other multi-material configurations can be utilized as desired.

[0221] In an embodiment, the spacer body 1010 can be connected to the cap 942 via the tether 1016 or in another manner. Referring to FIG. 32, for example, the tether 1016 is connected to the cap 942, thereby connecting the spacer body 1010 to the cap 942. Removal of the cap 942 can pull on the tether 1016 connected to the spacer body 1010 to remove the spacer body 1010 from between a portion of the analyte sensor 956 and the insertion element 915.

[0222] In an embodiment, the spacer body 1020 can be configured as a pin that can be positioned between the insertion element 915 and the analyte sensor 956. FIG. 33 illustrates such a configuration of the spacer body 1020, for example. The spacer body 1020 can operate similarly to the spacer body 1010 and can space the insertion element 915 from the analyte sensor 956.

[0223] As shown in FIG. 33, the spacer body 1020 can be coupled to a strut 1022 that is coupled to a liner removal component 928 or other removable component. The liner removal component 928 can comprise a cover (e.g., a liner cover) that can cover the distal surface of the housing of the skin sensor assembly. The liner removal component 928 can comprise a liner cover for the patch of the skin sensor assembly. The spacer body 1020 can be removed from between the insertion element 915 and the analyte sensor 956 upon removal of the liner removal component 928. In an example, the spacer body 1020 can be coupled to a tether in the form of a pull tab or tether coupled to a cap 942 as shown in FIG. 32. In an example, a spacer body 1010 as shown in FIGS. 31 and 32 can be coupled to the liner removal component 928 as desired.

[0224] In an example, the spacer body 1030 can comprise a sheath. For example, referring to FIG. 34A, the spacer body 1030 in the form of a sheath can separate the analyte sensor 956 from the insertion element 915. The sheath can surround the insertion element 915 and can include a portion 1032 positioned between the analyte sensor 956 and the insertion element 915 and a portion 1034 extending around the outer surface of the insertion element 915. The sheath can include a channel 1035 within which the analyte sensor 956 is positioned.

[0225] For example, FIG. 34B illustrates a perspective view of the spacer body 1030 surrounding the insertion element 915. FIG. 34C illustrates an end view of the analyte sensor 956 and the insertion element 915 separated by the spacer body 1030.

[0226] The spacer body 1030 can be positioned between the analyte sensor 956 and the insertion element 915 prior to a sterilization process. In other examples, the spacer body 1030 is installed in place after the sterilization process.

[0227] At a desired time point before application, the spacer body 1030 can be withdrawn from between the analyte sensor 956 and the insertion element 915, allowing the analyte sensor to seat within the channel 958 of the insertion element 915. The user can, for example, manually remove the spacer body 1030. The spacer body 1030 can be coupled to the cap 942 or the liner removal component 928, or to another device for removal in an embodiment as desired. The spacer body 1030 can be, for example, coupled to a tether for removal if desired.

[0228] In an embodiment, the spacer body 1040 can be positioned between a portion of the elongate analyte sensor 956 and the insertion element 915 and can separate a portion of the elongate analyte sensor 956 from the insertion element 915. The spacer body 1040 can be compressible and can be configured to compress to allow the analyte sensor 956 to seat within the insertion element 915. The spacer body 1040 can, for example, comprise a compressible body configured to compress over a certain duration. The spacer body 1040 can, for example, include a crushable body configured to crush after exposure to a sterilization process. For example, FIG. 35A illustrates the configuration of the spacer body 1040 in a non-compressed or expanded configuration, separating the analyte sensor 956 from the insertion element 915.

[0229] In an embodiment, the configuration shown in FIG. 35A can comprise the configuration of the analyte sensor 956 and the insertion element 915 positioned during or before sterilization. The configuration of FIG. 35B can include the post-sterilization configuration in an embodiment.

[0230] The spacer body 1040 can be positioned on the needle hub 914 or on an applicator or another component of the on-skin sensor assembly. For example, the spacer body 1040 can be positioned on the housing 1042 of the on-skin sensor assembly or on another component as desired.

[0231] The spacer body 1040 can be configured to compress, collapse, and / or reduce in size over time. The spacer body 1040 can be compressed, for example, as shown in FIG. 35B, to enable the analyte sensor 956 to seat within the insertion element 915. The reduced size of the spacer body 1040 can reduce the spacing between the analyte sensor 956 and the insertion element 915 and can enable the analyte sensor 956 to move within the channel 958 (e.g., shown in FIG. 28).

[0232] In an embodiment, the spacer body 1040 can simply compress due to the span of time or can collapse based on a sterilization process. For example, thermal cycling, humidity cycling, and / or exposure to a sterilization gas (e.g., EtO) can initiate the collapse of the spacer body 1040. Thus, after sterilization, the spacer body 1040 can gradually collapse and can seat the analyte sensor 956 within the insertion element 915. In an embodiment, the compression of the spacer body 1040 can occur over a span of several days or over a longer or shorter duration.

[0233] The features of the spacer body disclosed herein can reduce the friction between the analyte sensor and the insertion element and can reduce the likelihood of unwanted retraction of the analyte sensor 956 upon retraction of the insertion element 915. In an embodiment, the spacer body can prevent friction (e.g., static friction) from occurring between the analyte sensor 956 and the insertion element 915. The spacer body can be utilized before or during the sterilization process and / or after the sterilization process. In an embodiment, the spacer body can be utilized as desired in an applicator and in the packaging and / or distribution of the sensor assembly on the skin. The use of the spacer body can be utilized alone or in combination with any of the systems, devices, or methods disclosed herein.

[0234] In an embodiment, the stopper body can be configured to prevent the analyte sensor 956 from retracting proximally through the opening 978 through which the insertion element 915 extends when the insertion element 915 retracts proximally through the opening 978.

[0235] For example, FIG. 36 illustrates a stopper body 1050 positioned proximate to the opening 978. The stopper body 1050 can be positioned within the opening 978 and can project into the opening 978. The stopper body 1050 can include tabs extending into the opening 978. In an embodiment, the stopper body 1050 can be positioned proximal to the analyte sensor 956. The stopper body 1050 can be positioned within the opening 978 or proximal to the opening 978 (e.g., on or above the proximal surface of the housing 1052 among other locations).

[0236] FIGS. 36 and 38 illustrate a stopper body 1050 having an angled surface and extending into the opening 978. FIG. 37A illustrates an enlarged perspective view of a stopper body 1050 having a flat surface and extending into the opening 978. FIG. 37B illustrates an enlarged perspective view of a stopper body 1050 having a protruding surface and extending into the opening 978. The surface portion of the stopper body 1050 can be spaced apart from the analyte sensor 956 or can first contact it prior to insertion. The surface portion of the stopper body 1050 is designed to contact the analyte sensor 956 when the friction between the analyte sensor 956 and the insertion element 915 begins to remove the analyte sensor 956 from the recipient's skin upon retraction of the insertion element 915. The stopper body 1050 reduces the bending moment applied to the analyte sensor 956 by the insertion element 915 upon retraction by supporting the analyte sensor 956 at a point closer to the insertion element 915.

[0237] In an embodiment, the stopper body 1050 can include an insert into the housing 1052 of the on-skin sensor assembly or can include a molded portion of the housing 1052. For example, FIG. 38 illustrates a perspective view of a stopper body 1050 including an insert in the form of a ring that can be inserted into the opening 978. The ring can be positioned distal to the needle hub 914 but proximal to the analyte sensor 956. The stopper body 1050 can thus be positioned between the needle hub 914 and the analyte sensor 956.

[0238] FIG. 39 illustrates a distal view of the stopper body 1050 protruding into the opening 978.

[0239] Referring to FIG. 36, when the insertion element 915 retracts from the recipient's skin and the opening 978, the stopper body 1050 can contact the analyte sensor 956 to prevent the analyte sensor 956 from retracting proximally as the insertion element 915 retracts proximally through the opening 978. Accordingly, a reduced likelihood of retraction of the analyte sensor 956 from the skin, and a reduced likelihood of a flexure 990 as shown in FIG. 27B, can result.

[0240] In an embodiment, the stopper body can have other forms. FIG. 40 illustrates an embodiment in which the stopper body 1060 can protrude from a cavity 1062 configured to receive a first portion 960 of the analyte sensor 956. The cavity 1062 can be configured similarly to the cavity 976 shown in FIG. 26A. The cavity 1062 can be configured to receive, for example, an adhesive in a (curable) liquid form. The cavity 1062 can include one or more tacking dams for retaining the adhesive or other forms of curable liquid. The stopper body 1060 can include a tab extending from the cavity 1062 into the opening 978.

[0241] In an embodiment, the stopper body 1070 can be integrated with the housing 1072. The stopper body 1070 can include a portion of the housing 1072.

[0242] The stopper body can, in an embodiment, surround the insertion element 915 and can fit closely to the insertion element 915. For example, FIG. 41 illustrates a stopper body 1070 including a surface of the housing 1072 having a fit around the insertion element 915 that prevents the analyte sensor 956 from retracting proximally through the opening 978. Further, the fit of the stopper body 1070 to the insertion element 915 can allow the insertion element 915 to extend perpendicular to the distal surface 1074 of the housing 1072 and to the recipient's skin. The perpendicular angle 1076 of insertion into and retraction from the recipient's skin can further reduce the likelihood of the analyte sensor 956 retracting from the recipient's skin.

[0243] The systems, methods, and apparatuses disclosed herein may include providing a vertical insertion angle into the recipient's skin and a vertical angle of the insertion element from the distal surface of the housing of the skin-mounted sensor assembly. The size of the opening 978 within the housing through which the insertion element 915 passes may be determined and set to provide such verticality.

[0244] In an example, the stopper body may include a plug positioned within the opening 978. Referring to FIG. 42, the plug 1080 may have a chamfered portion that can be angled to contact the analyte sensor 956. The plug 1080 may be positioned, for example, within the opening 978 and include an annular shape (e.g., a washer) with a chamfered portion. The plug 1080 may be inserted into the opening 978 before or after assembly of the analyte sensor 956 to the housing 1052. The angled surface of the plug 1080 may contact the analyte sensor 956 upon retraction of the insertion element 915 to prevent retraction of the analyte sensor 956.

[0245] In an example, the plug may include a gasket 1090. Referring to FIG. 43, the gasket 1090 may be inserted into the opening 978 and may fit onto the insertion element 915. In an example, the gasket 1090 may include a self-healing gasket and may conform to the shape of the insertion element 915. The gasket 1090 may contact the analyte sensor 956 to prevent retraction of the analyte sensor 956 upon retraction of the insertion element 915. In an example, the gasket 1090 may be overmolded as part of the housing 1052.

[0246] In an embodiment, the plug 1100 may be pierceable by the insertion element 915. Referring to FIG. 44, the plug 1100 may be pierceable such that during assembly of the sensor assembly on the skin, the insertion element 915 can pierce the plug 1100 so that the plug 1100 conforms to the shape of the insertion element 915. Thus, the stopper body in the form of the plug 1100 can contact the analyte sensor 956 to prevent the analyte sensor 956 from retracting when the insertion element 915 retracts. The stopper body may be selected to include a biocompatible and / or compliant material in an embodiment.

[0247] The use of the stopper body can be utilized alone or in combination with any system, device, or method disclosed herein. The stopper body can be provided during, after, or before the sterilization process or in the absence of a sterilization process. The stopper body can be packaged in circulation with the components of the insertion element, the analyte sensor, and / or the applicator system. The stopper body can be utilized during deployment of the insertion element and the analyte sensor. The stopper body can increase the resistance of the analyte sensor to buckling forces applied proximally to the analyte sensor during insertion into the recipient's skin and when the insertion element retracts.

[0248] In an embodiment, the stopper body can be added after the process of loading the analyte sensor onto the insertion element. For example, the stopper body can be added proximally to the analyte sensor. For example, the plug can be inserted into the opening of the housing, or another method of providing the stopper body can be utilized. The stopper body can be press-fit or snap-fit, or another form of insertion can be used so that it remains within the housing when the insertion element 915 retracts. In an embodiment, the stopper body can be injection molded to extend within the opening of the housing. Other forms of formation or insertion of the stopper body can be utilized as desired.

[0249] In an embodiment, a displacement mechanism, which may be configured to displace a portion of the analyte sensor 956 relative to the insertion element 915, may be utilized prior to retraction of the insertion element 915 from the recipient's skin. The displacement mechanism may displace the analyte sensor 956 relative to the insertion element 915 to reduce the static friction between the analyte sensor 956 and the insertion element 915.

[0250] In an embodiment, the displacement mechanism may be configured to slide a portion (e.g., the second portion 966 or the sensing portion) of the analyte sensor 956 relative to the shaft 986 of the insertion element 915. The displacement mechanism may slide a portion of the analyte sensor 956 prior to retraction of the shaft 986 from the skin to reduce (e.g., break) the friction between the analyte sensor 956 and the shaft 986.

[0251] Referring to FIG. 45, the displacement mechanism may include a compressible body 1082 that may be positioned between the needle hub 914 and the proximal surface 972 of the housing 962 of the on-skin sensor assembly. FIG. 46 illustrates a top view of the housing 962 with the compressible body 1082 positioned on the proximal surface 972. The compressible body 1082 may surround an opening 978 within the housing 962.

[0252] The compressible body 1082 can be configured to compress when distal pressure from the needle hub 914 is applied to the compressible body 1082. Thus, referring to FIG. 25, the needle carrier assembly 910 or other components of the insertion assembly can apply a distal force to the needle hub 914 during deployment. Thus, when inserting the insertion element 915 and the analyte sensor 956 into the recipient's skin, the compressible body 1082 can compress. Compression of the compressible body 1082 can allow the needle hub 914 to move distally relative to the housing 962 and the analyte sensor 956 and to continue to move distally relative to the housing 962 and the analyte sensor 956. The insertion element 915 can be inserted further distally than the analyte sensor 956. FIG. 47 illustrates, for example, the continuous movement of the insertion element 915 from the leftmost portion of FIG. 47 to the rightmost portion of FIG. 47. The insertion element 915 can move independently of the analyte sensor 956 after reaching a full or maximum depth. Displacement of the insertion element 915 relative to the analyte sensor 956 can reduce friction (e.g., break static friction) between the insertion element 915 and the analyte sensor 956. Thus, upon retraction of the insertion element 915, a reduced likelihood of retraction of the analyte sensor 956 from the skin and a reduced likelihood of a bend 990 as shown in FIG. 27B can result.

[0253] Furthermore, the displacement mechanism can include a second compressible body 1084 (shown in FIG. 46) to which the needle carrier assembly 910 can apply further force. The second compressible body 1084 can operate in a manner similar to the first compressible body 1082.

[0254] Figures 48 and 49 illustrate another form of displacement mechanism in which the displacement mechanism can be configured to slide a portion of the analyte sensor 956 (e.g., the second portion 966 including the sensing portion) relative to the shaft 986 of the insertion element 915. The analyte sensor 956 can be displaced relative to the housing 962. The displacement mechanism can include a compressible body 1092 that projects distally from the distal surface 968 of the housing 962 and can be configured to apply a proximal force upon contact with the recipient's skin. The compressible body 1092 can have a distal end 1093 configured to contact the recipient's skin and a proximal end 1094 configured to contact the analyte sensor 956.

[0255] Referring to FIG. 49, when the insertion element 915 and the housing 962 are advanced distally so as to contact the recipient's skin 1096 during the deployment or insertion process, the distal end 1093 of the compressible body 1092 can contact the skin 1096 and thus drive the proximal end 1094 to contact the analyte sensor 956. The analyte sensor 956 can move proximally independently of the insertion element 915 after the insertion element 915 reaches a full or maximum depth. The analyte sensor 956 can be displaced proximally relative to the housing 962 and the insertion element 915, thus reducing the friction (e.g., static friction) between the insertion element 915 and the analyte sensor 956. When the insertion element 915 is retracted, a reduced likelihood of retraction of the analyte sensor 956 from the skin and a reduced likelihood of a bend 990 as shown in FIG. 27B can result.

[0256] FIG. 50 illustrates an embodiment of a displacement mechanism configured to vibrate one or more of the insertion element 915 (e.g., the shaft 986) or the analyte sensor 956 (e.g., the second portion 966 or the sensing portion) prior to retraction of the insertion element 915 from the skin to break the static friction between the analyte sensor 956 and the insertion element 915. The displacement mechanism can be configured to generate vibrations when the analyte sensor 956 is deployed distally into the recipient's skin. The insertion assembly can include the displacement mechanism in an embodiment.

[0257] The displacement mechanism may include one or more ridges 1105 for contacting a portion of the insertion assembly, e.g., to vibrate the insertion assembly during deployment. The ridges 1105 may be positioned on the inner housing 906, e.g., as shown in FIG. 25, and / or the ridges 1105 may be positioned on the holder 912, the needle carrier assembly 910, and / or, optionally, other components of the applicator. The ridges 1105 may be utilized to vibrate the sensor assembly on the skin and / or the needle hub 914 or other components during insertion to reduce friction (e.g., break static friction) between the insertion element 915 and the analyte sensor 956. Upon retraction of the insertion element 915, a reduced likelihood of retraction of the analyte sensor 956 from the skin and a reduced likelihood of a bend 990 as shown in FIG. 27B may result.

[0258] FIG. 51 illustrates an example including a displacement mechanism positioned on a cover covering the distal surface of the housing 962. The cover may include an optional liner removal component 928 that may comprise a liner cover for a patch of the sensor assembly on the skin. The displacement mechanism may be configured to vibrate one or more of the insertion element 915 or the analyte sensor 956 upon withdrawal of the liner removal component 928 from the housing 962 and the patch 922. The liner removal component 928 may include one or more ridges 1110 that may contact the insertion element 915 and / or the analyte sensor 956 upon removal of the liner removal component 928. The vibrations caused by the ridges 1110 may reduce friction (e.g., break static friction) between the insertion element 915 and the analyte sensor 956. Upon retraction of the insertion element 915, a reduced likelihood of retraction of the analyte sensor 956 from the skin and a reduced likelihood of a bend 990 as shown in FIG. 27B may result.

[0259] Figures 52 - 54 illustrate an embodiment of a displacement mechanism positioned on a cover covering the distal surface of housing 962. The cover may comprise a cap 1120 with a displacement mechanism. Cap 1120 may be positioned at the distal opening of the applicator housing and may be configured similarly to cap 942 shown in Figure 25, including a displacement mechanism in the form of a cam surface 1122. Cam surface 1122 may be configured to apply a force to housing 962 to displace a portion of analyte sensor 956 (e.g., second portion 966 or sensing portion) relative to insertion element 915. Cam surface 1122 may vibrate one or more of analyte sensor 956 or insertion element 915.

[0260] Cam surface 1122 may be positioned on a central support 1124 of cap 1120 and may extend proximally from central portion 948 of cap 942. Cam surface 1122 may be configured to be positioned within a cavity of housing 962 that may receive cam surface 1122. As cap 1120 rotates (in a decoupling movement, unscrewing movement, or cap removal movement), cam surface 1122 may rotate its position to contact the distal surface of housing 962 or patch 922. For example, Figure 53 illustrates a schematic cross - sectional view where cam surface 1122 is positioned within a cavity of housing 962. Figure 54 illustrates cap 1120 rotated such that cam surface 1122 exits the cavity of housing 962 and contacts the distal surface of housing 962 or patch 922. Accordingly, housing 962 is displaced proximally in Figure 54. The displacement of housing 962 due to cam surface 1122 may cause analyte sensor 956 to vibrate and displace relative to insertion element 915 and may reduce the friction (e.g., break static friction) between insertion element 915 and analyte sensor 956. Accordingly, during cap removal operation, the friction between insertion element 915 and analyte sensor 956 may be reduced. Continuous rotation of cap 1120 may cause housing 962 to continue to be vibrated by cam surface 1122 to continue reducing the friction between insertion element 915 and analyte sensor 956. When insertion element 915 retracts, a reduced likelihood of retraction of analyte sensor 956 from the skin and a reduced likelihood of bend 990 as shown in Figure 27B may result.

[0261] The displacement mechanism can be used alone or in combination with any system, device, or method disclosed herein. The use of the displacement mechanism can occur after the sterilization process or, in an embodiment, before or during the sterilization process. In an embodiment, the use of the displacement mechanism can occur without a prior sterilization process.

[0262] In an embodiment, a force channeling component configured to direct a force from the insertion assembly in proximity to the insertion element 915 can be utilized. The force channeling component can reduce friction (e.g., static friction) between the analyte sensor 956 and the insertion element 915.

[0263] Referring to FIG. 55, components of the insertion assembly, such as the holder 1130, can include a force channeling component 1132. The holder 1130 can be configured similarly to the holder 912 shown in FIG. 25. A portion of the insertion assembly, such as the holder 1130, can include a plate 1134 configured to be positioned proximal to the proximal surface 972 of the housing 962. The plate 1134 can include an opening 1136 for the needle hub 914 to pass through.

[0264] The force channeling component 1132 can include one or more protrusions 1138 configured to direct the force of the insertion assembly in proximity to the needle hub 914 and the insertion element 915. The one or more protrusions 1138 can be positioned on the plate 1134. The one or more protrusions 1138 can contact the proximal surface 972 of the housing 962 and be configured to apply a force to the proximal surface 972 in proximity to the insertion element 915. The one or more protrusions 1138 can contact the proximal surface 972 in proximity to the opening 978 of the housing 962 through which the insertion element 915 passes.

[0265] One or more protrusions 1138 can direct the deployment force proximate to the needle hub 914 and the insertion element 915. The force from the force channeling component 1132 can displace the analyte sensor 956 relative to the insertion element 915 and can reduce the friction between the insertion element 915 and the analyte sensor 956 (e.g., can break static friction). The force from the force channeling component 1132 can vibrate the analyte sensor 956 relative to the insertion element 915 or can transmit vibrations to the analyte sensor 956. Upon retraction of the insertion element 915, a reduced likelihood of retraction of the analyte sensor 956 from the skin and a reduced likelihood of a flexure 990 as shown in FIG. 27B can result. In an example, the force channeling component can contact the proximal surface 972 of the housing 962 after the insertion element 915 has penetrated the skin.

[0266] The use of the force channeling component can be utilized alone or in combination with any system, device, or method disclosed herein.

[0267] In an example, the analyte sensor can be configured to reduce friction (e.g., static or kinetic friction) with the insertion element 915. FIG. 56 illustrates an example of an analyte sensor 1140 having an elliptical cross-section. FIG. 57 illustrates a cross-sectional view of the analyte sensor 1140 and the insertion element 915 along line C-C' in FIG. 56. The outer surface 1141 of the analyte sensor 1140 can be configured to reduce friction (e.g., static friction) with the insertion element 915. The elliptical cross-section can reduce the distance or clearance of the analyte sensor 1140 from the sidewall 988 of the insertion element 915 and, thus, can reduce friction with the insertion element 915. For example, the channel 958 of the insertion element 915 can have a C-shaped cross-section that can increase the diametrical clearance from the sidewall 988 to the elliptical analyte sensor 1140. Further, a reduced contact point or contact surface area between the elliptical analyte sensor 1140 and the insertion element 915 can result.

[0268] The features of FIGS. 56 and 57 can be utilized alone or in combination with any system, device, or method disclosed herein.

[0269] In an embodiment, the analyte sensor may have a surface configured to reduce friction with the insertion element 915. For example, the surface of the analyte sensor may include an outer surface configured to reduce the static friction with the insertion element 915. The surface may be configured to reduce, for example, hydrogen bonding with the insertion element 915. In an embodiment, the membrane including the outer surface of the analyte sensor may have properties that can prevent hydrophilic permeability and / or membrane swelling. For example, the ratio of polyvinylpyrrolidone (PVP) may be varied (e.g., reduced) to prevent hydrophilic permeability and / or membrane swelling. The features of the surface of the insertion element disclosed herein may also be utilized with the surface of the analyte sensor.

[0270] In an embodiment, the analyte sensor may be oriented to increase the resistance to buckling force of the analyte sensor and thus provide a reduced likelihood of the analyte sensor retreating from the skin and a reduced likelihood of the flexure 990, as shown in FIG. 27B. Referring to FIG. 58, for example, the analyte sensor 1143 may include a first portion 1144 or contact portion and a second portion 1145 or sensing portion. The first portion 1144 may be coupled to the housing 962, and the second portion 1145 may extend distally from the housing 962 and be configured to be inserted into the skin of the recipient.

[0271] The flexure 1146 of the analyte sensor 1143 may have at least two kinks 1147, 1148 that may angularly displace the second portion 1145 from the first portion 1144. The first kink 1147 may be positioned between the first portion 1144 and the intermediate portion 1149 of the analyte sensor 1143. The second kink 1148 may be positioned between the intermediate portion 1149 and the second portion 1145.

[0272] The first kink 1147 may have an angle of less than 90 degrees. For example, the first kink 1147 may have an angle of 30 degrees to 60 degrees, which may be an angle of 45 degrees, or another angle may be utilized as desired. Similarly, the second kink 1148 may have an angle of 30 degrees to 60 degrees, which may be an angle of 45 degrees, or another angle may be utilized as desired. In an embodiment, at least two kinks 1147, 1148 may angularly position the second portion 1145 so as to be perpendicular to the first portion 1144. The second portion 1145 may extend perpendicularly from the distal surface 968 of the housing 962, or at another angle as desired. In an embodiment, the first portion 1144 may extend parallel to the distal surface 968 of the housing 962. Various other angles may be utilized as desired.

[0273] The intermediate portion 1149 of the analyte sensor 1143 may be straight or linear. In an embodiment, the intermediate portion 1149 may have a curvature as desired.

[0274] The use of the kinks 1147, 1148 may improve the strength of the analyte sensor 1143 in response to a buckling force or a retraction force applied to the analyte sensor (in the direction indicated by the arrow in FIG. 58). An increase in the strength of the analyte sensor 1143 in response to a buckling force may result in a reduced likelihood of retraction of the analyte sensor 956 from the skin and a reduced likelihood of a flexure 990 as shown in FIG. 27B.

[0275] The features of FIG. 58 may be utilized alone or in combination with any system, device, or method disclosed herein.

[0276] In an embodiment, other configurations of the analyte sensor may be utilized to increase the strength of the analyte sensor in response to a buckling force. For example, the rigidity of the analyte sensor may be increased. A harder alloy of the sensor may be utilized as desired.

[0277] In an embodiment, the insertion element 915 can be configured to reduce friction (e.g., static friction or kinetic friction) with the analyte sensor 956. Referring to FIG. 59, for example, the surface 1152 of the insertion element 915 (e.g., the surface 1152 of the shaft of the insertion element 915) can be configured to reduce friction with a portion of the analyte sensor (e.g., the second portion 966 or the sensing portion). In an embodiment, a metal or alloy can be selected for the insertion element 915 that can reduce friction with the analyte sensor 956.

[0278] In an embodiment, the surface 1152 can include a coating configured to reduce friction with a portion of the analyte sensor 956. The coating can be, for example, a lubricant that can be positioned on a portion of the insertion element. The lubricant can include a biocompatible lubricant. Mineral oil (petrolatum) can be utilized in an embodiment among other forms of lubricants. In an embodiment, the coating can include a polymer. For example, a plastic coating such as a thin plastic coating can be utilized. Polymers such as polytetrafluoroethylene (PTFE), parylene, or another form of polymer can be coated on the insertion element. Vapor deposition can be utilized to apply the polymer to the insertion element 915.

[0279] In an embodiment, the coating can include a thermal oxide. The thermal oxide can be formed, for example, on the insertion element 915 including aluminum or titanium.

[0280] In an embodiment, the coating of the insertion element 915 can include an inert material. For example, an inert material having a low surface energy can be utilized to reduce the possibility of hydrogen bonding or other forms of electrical bonding with the analyte sensor. For example, an inert material such as silane (SiH4) can be utilized.

[0281] In the embodiments, the coating of the insertion element 915 may include one or more of spray coating, brush coating, electrostatic coating, anodization, or more preferably plating, dip coating, or vapor deposition. Vapor deposition, including chemical vapor deposition and physical vapor deposition, may be utilized in the embodiments. For example, the vapor deposition of chromium nitride, titanium nitride, and titanium carbonitride can be applied to the insertion element 915. In certain embodiments, the thickness of the nitride coating is 10 to 5000 nanometers (nm), preferably 100 to 1000 nm. Plating may include plating such as titanium, nickel, gold, other forms of plating, and their alloys.

[0282] In the embodiments, a coating that can be bonded to the shaft of the insertion element 915 may be provided. The coating may be chemically bonded in the embodiments. The coating may be provided as plating, dip coating, or vapor deposition (which may be spray coating, chemical vapor deposition, or physical vapor deposition) among other processes. The coating material may be silicone-based, fluorine compound-based, or parylene-based among other materials.

[0283] The coating may be cured in the embodiments. The coating may be cured via addition curing, condensation curing, thermal curing, and other curing methods. The coating to be cured may be applied in various manners disclosed herein. Curing may generate cross-linking that can improve the adhesion and cohesion of the coating on the insertion element 915 and the robustness of the coating. The coating embodiments herein may have processes such as heating, evaporation, or other processes performed on them to facilitate curing. Curing may be performed at room temperature in the embodiments.

[0284] In an embodiment, the coating may include silicone. The coating may be obtained from a silane (SiH4) compound. In an embodiment, the silicone may include an amino-functional dimethylsiloxane copolymer. The material may be provided as a compound of about 50% active silicone component (e.g., amino-functional dimethylsiloxane copolymer) mixed with one or more solvents. The solvents may include aliphatic hydrocarbons and isopropanol solvents in an embodiment. Other proportions of the components including the material may be provided in an embodiment (e.g., about 45% - 55% active silicone component, about 40% - 60% active silicone component, etc.). Other forms of solvents may be utilized in an embodiment. Other forms of materials for the coating may be utilized in an embodiment.

[0285] FIG. 67 illustrates exemplary steps in a method of coating at least a portion of the shaft 986 of the elongated insertion element 915. The coating may be a material configured to reduce static friction and friction between the elongated insertion element 915 and the elongated analyte sensor 956. In an embodiment, other forms of application of the material may be utilized as disclosed herein (e.g., spray coating or other forms of vapor deposition).

[0286] FIG. 67 illustrates the shaft 986 of the elongated insertion element 915 positioned within the bath 1162. The bath 1162 may contain the material therein. A solution of the material may be provided. For example, in an embodiment where the material includes a compound of an active silicone component (e.g., amino-functional dimethylsiloxane copolymer) mixed with one or more solvents, this material may be combined with or diluted with an additional solvent. The material may be added to the additional solvent to produce a mixture of about 0.1% material (e.g., amino-functional dimethylsiloxane copolymer mixed with the solvent) in the bath of the additional solvent. The proportion of the material to the additional solvent may be varied as desired. For example, concentrations of about 0.05%, 0.2%, 0.3%, 1.0%, or more of the material may be provided as desired. The additional solvent may include hexane or other forms of solvents.

[0287] The shaft 986 of the elongated insertion element 915 can be positioned within the bath 1162 for a desired duration (e.g., less than 30 minutes, or another duration as desired). The thickness of the material on the shaft 986 of the elongated insertion element 915 can be determined by the duration within the bath 1162. Free silicone molecules can chemically bond to the surface of the shaft 986 of the elongated insertion element 915. The polar ends of any amino functional groups can adhere to the metal shaft 986 to form a densely packed layer on the surface. The shaft 986 can be withdrawn from the bath 1162 (a partial withdrawal is shown in FIG. 67) to produce a layer 1164 of material on the shaft 986 as represented as shown in FIG. 67.

[0288] The layer 1164 can be cured on the shaft 986. For example, FIG. 68 illustrates the shaft 986 outside of the bath 1162. The material can cure at room temperature, or other curing methods (e.g., especially heating or evaporation) can be utilized. Air or another gas can be blown onto the material during the curing process. Ambient (room) relative humidity can be utilized. Curing can occur over a desired duration (e.g., about one week, less than 24 hours, less than 30 minutes, or a longer or shorter duration as desired). Curing can produce cross-linking that can improve the adhesion and cohesion of the coating on the insertion element 915 and the robustness of the coating. Permanent chemical bonds can result.

[0289] The resulting layer 1164 on the outer surface of the shaft 986 of the insertion element 915 is represented in FIG. 69. The layer 1164 can have a thickness as desired, based on the selected coating material, the duration in the bath, and the curing process and duration utilized. In an example, the layer 1164 can have a thickness 1166 of less than 1 micrometer on the shaft 986. In an example, the layer 1164 can have a thickness 1166 of less than 1.5 micrometers on the shaft 986. In an example, the layer 1164 can have a thickness 1166 of less than 2 micrometers on the shaft 986. In an example, the layer 1164 can have a thickness 1166 in the range of 0.1 micrometer to 1, 1.5, or 2 micrometers. In an example, the layer 1164 can have a thickness 1166 in the range of 0.5 micrometer to 1, 1.5, or 2 micrometers. Larger or smaller thicknesses can be provided as desired.

[0290] In an example, the channel 958 of the insertion element 915 can include a layer of material. For example, FIG. 70 illustrates the inner surface of the insertion element 915 forming the channel 958 in which a layer of material is provided. The layer can have a thickness in the amounts disclosed herein.

[0291] The layer of material can advantageously be stable and durable. The layer of material can have very few extractables and leachables and is thus safe for use in medical insertion applications. The layer of material can reduce the static and frictional forces of the insertion element 915 with the analyte sensor 956 and the local tissue. The material can reduce the friction (e.g., static or kinetic friction) with the elongate analyte sensor 956. Improved deployment reliability and accuracy can be generated. Reduced insertion tissue damage can be provided.

[0292] In an example, the material can produce a coefficient of friction of the shaft 986 that is less than one tenth of the coefficient of friction of the surface 1171 (marked in FIG. 69) of a portion of the shaft 986 coated with the material. In an example, larger or smaller variations in the coefficient of friction can be provided.

[0293] After the coating process, additional assembly steps may be provided using the insertion element 915. For example, the elongated insertion element 915 may be positioned adjacent to the elongated analyte sensor 956. The elongated analyte sensor 956 may be positioned within the channel 958 of the elongated insertion element 915 as disclosed herein. The elongated analyte sensor 956 may be configured similarly to other forms of analyte sensors disclosed herein. For example, the elongated analyte sensor 956 may extend distally from a housing 962 configured to be worn on a recipient's skin. Other assembly steps may be provided after or before the coating process.

[0294] The methods disclosed herein may be utilized with other forms of materials. The steps of the methods may be substituted, excluded, added, or modified as desired.

[0295] In an embodiment, the surface of the insertion element 915 may include surface roughness. For example, referring to FIG. 60, the surface 1154 may include a plurality of ridges. The raised portions of the ridges may contact the analyte sensor 956, may reduce the contact surface area, and thus may reduce the friction with the analyte sensor 956. In an embodiment, the height of the ridges may be varied as desired. For example, the surface roughness may be 35 root mean square (RMS) microinches or greater in an embodiment. In an embodiment, the surface roughness may be 40 RMS microinches or greater. In an embodiment, the surface roughness may be 45 RMS microinches or greater. Larger or smaller surface roughnesses may be provided as desired.

[0296] The surface 1154 of the insertion element 915 may be the inner surface facing the analyte sensor 956. The inner surface may be positioned within the channel 1155 of the insertion element 915.

[0297] The surface of the insertion element may have a surface texture. The texture may include one or more patterns of raised portions of the surface. For example, FIG. 61 illustrates a front view of channel 1157 of an insertion element showing an inner surface 1159 having a surface texture. The insertion element 915 may have sidewalls 1161 bounding the channel 1157. The texture reduces the total surface area contact between the analyte sensor 956 and the insertion element 915, and thus reduces friction.

[0298] In an embodiment, the surface of the insertion channel 915 may include grooves. For example, FIG. 62 illustrates a front view of channel 1163 of an insertion element showing an inner surface 1165 having grooves 1158. The grooves 1158 may extend along the longitudinal axis of the channel 1163 and, if desired, may be straight, angled, or curved. For example, as shown in FIG. 62, the grooves 1158 may intersect in a repeating curved pattern. The grooves 1158 may be configured in a spiral or helical or other configuration, if desired. The grooves may be etched by laser, mechanically, chemically, or formed by another method. The grooves 1158 reduce the total surface area contact between the analyte sensor 956 and the insertion element 915, and thus reduce friction.

[0299] For example, the surface of the insertion channel 915 may include holes. For example, FIG. 63 illustrates a front view of channel 1167 of an insertion element showing an inner surface 1156 having holes 1160. The holes 1160 may be arranged in a pattern that may extend along the longitudinal axis of the channel 1167. For example, a repeating pattern of longitudinally aligned holes 1160 may be utilized, or another pattern may be provided, if desired. The holes 1160 reduce the total surface area contact between the analyte sensor 956 and the insertion element 915, and thus reduce friction.

[0300] In an embodiment, the surface of the insertion element may include one or more of bumps, holes, or grooves. The surface may be configured to reduce friction (e.g., static or kinetic friction) with a portion of the analyte sensor 956. For example, the surface may reduce hydrogen bonding sites between the analyte sensor 956 and the insertion element 915, among other forms of reduced friction (e.g., electrical or mechanical).

[0301] The channels of the insertion element 915 shown in FIGS. 59-63 may have a C-shaped cross-section. In an embodiment, other cross-sectional shapes may be provided.

[0302] For example, FIG. 64 illustrates a top cross-sectional view showing an insertion element 1170 having a V-shaped cross-section channel 1172 for receiving a portion of the analyte sensor 956. The shaft 1174 of the insertion element 1170 may include the V-shaped cross-section channel 1172.

[0303] The V-shape of the channel 1172 may be formed by side walls 1176 of the insertion element 1170 that are angled relative to each other. Accordingly, the inner surfaces 1178 of the side walls 1176 may be angled relative to each other. In an embodiment, the V-shaped cross-section channel 1172 may have an angle of 60 degrees to 120 degrees. In an embodiment, the V-shaped cross-section channel 1172 may have an angle of 90 degrees. In an embodiment, larger or smaller angles may be provided as desired. The inner surface 1178 may comprise a flat wall positioned to contact the circular analyte sensor 956 at only two contact points. A reduced surface area may result, and thus reduced friction (e.g., static or kinetic friction) may result.

[0304] FIG. 65 illustrates a top cross-sectional view showing an insertion element 1180 having a W-shaped cross-section channel 1182 for receiving a portion of the analyte sensor 956. The shaft 1184 of the insertion element 1180 may include the W-shaped cross-section channel 1182.

[0305] The W-shape of channel 1182 can be formed by an elongated protrusion 1186 added to the central portion 1188 of an elongated insertion element 1180 having a C-shaped cross-sectional channel. Thus, the C-shaped cross-sectional channel can be modified to produce a W-shaped cross-sectional channel 1182 by the addition of the protrusion 1186. A reduced number of possible contact points can result between the insertion element 1180 and the analyte sensor 956. For example, the outer surface of the analyte sensor 956 can have a circular cross-section. Thus, a reduced friction (e.g., static or kinetic friction) can result.

[0306] FIG. 66 illustrates a top cross-sectional view showing an insertion element 1190 having a W-shaped cross-sectional channel 1192 for receiving a portion of the analyte sensor 956. The shaft 1194 of the insertion element 1190 can include the W-shaped cross-sectional channel 1192.

[0307] The W-shape of channel 1192 can be formed by shaping (e.g., stamping) the shaft 1194 into a W-shape. A reduced number of contact points or surface area can result between the insertion element 1190 and the analyte sensor 956, and thus, a reduced friction (e.g., static or kinetic friction) can result.

[0308] FIG. 71 illustrates a configuration in which one or more elongated insertion elements 1200 are utilized (elongated insertion elements 1200a and 1200b are marked in FIG. 71). Each of the elongated insertion elements 1200 can include respective shafts 1202a, b configured to extend along a portion of the elongated analyte sensor 956.

[0309] Each of the elongated insertion elements 1200 can be configured to guide the elongated analyte sensor 956 into the recipient's skin with the elongated analyte sensor 956 positioned external to the shafts 1202a, b of the respective elongated insertion elements 1200a, b. Thus, the elongated insertion elements 1200a, b can lack a channel for holding the elongated analyte sensor 956, for example, as shown in FIG. 28. Rather, the elongated analyte sensor 956 can be positioned external to the shafts 1202a, b in an arrangement as shown in the cross-sectional view of FIG. 72. In an embodiment, the elongated insertion element 1200 can have a solid center or interior. In an embodiment, the elongated insertion element 1200 can include a pin or pin-shaped needle. In an embodiment, the elongated insertion element 1200 can be hollow or can have a channel, but the elongated analyte sensor 956 is positioned external to the shaft of such an elongated insertion element.

[0310] Each of the elongated insertion elements 1200 can extend along respective central axes 1204a, b. The elongated analyte sensor 956 can include a central axis 1206. The central axis 1206 of the elongated analyte sensor 956 can be configured to be positioned parallel to and laterally spaced apart from each of the central axes 1204a, b of the elongated insertion elements 1200 (e.g., as shown in FIG. 72). In an embodiment, the second portion 966, sensing portion, or distal portion of the elongated analyte sensor 956 can include a central axis 1206 that extends parallel to and laterally spaced apart from each of the central axes 1204a, b of the elongated insertion elements 1200.

[0311] In an embodiment, each of the elongated insertion elements 1200 can include respective outer surfaces 1208a, b. The outer surfaces 1208a, b of the elongated insertion elements 1200a, b can extend parallel to each other. The elongated analyte sensor 956 can be positioned external to the respective outer surfaces 1208a, b. The elongated analyte sensor 956 can include an outer surface 1210.

[0312] FIG. 72 illustrates a cross-sectional view of the arrangement of FIG. 71 from a perspective perpendicular to the central axes 1204a, b, 1206. The outer surface 1208a of the elongated insertion element 1200a may include a longitudinally extending segment 1212a configured to extend parallel to and adjacent to the outer surface 1210 of the elongated analyte sensor 956. The longitudinally extending segment 1212a may include only the entire circumference or a portion of the outer periphery of the outer surface 1208a. The longitudinally extending segment 1212a may extend over the entire length of the insertion element 1200a or, in an embodiment, may extend only over a portion of the length. The outer surface 1208b of the elongated insertion element 1200b may similarly include a longitudinally extending segment 1212b. In an embodiment, the longitudinally extending segments 1212a, b may face each other.

[0313] The longitudinally extending segments 1212a, b, each comprising only the entire circumference or a portion of the outer periphery of the respective outer surfaces 1208a, b, may generate longitudinally extending contact surfaces 1214a, b for the respective elongated insertion elements 1200a, b. The longitudinally extending contact surfaces 1214a, b may comprise only the entire circumference or a portion of the outer periphery of the respective outer surfaces 1208a, b and thus generate a relatively narrow or thin line contact region between the outer surfaces 1208a, b and the elongated analyte sensor 956. As a result, a reduced static friction, friction, and contact surface area between the elongated insertion elements 1200a, b and the elongated analyte sensor 956 may result.

[0314] In an embodiment, the respective outer surfaces 1208a, b and the longitudinally extending segments 1212a, b may include convex outer surfaces. The convex outer surfaces may bend radially outward and may further reduce the size of the longitudinally extending contact surfaces 1214a, b that may contact the outer surface 1210 of the elongated analyte sensor 956. In an embodiment, other shapes of the outer surfaces 1208a, b or the longitudinally extending segments 1212a, b may be utilized (e.g., flat, triangular, rectangular, pentagonal, hexagonal, among others).

[0315] FIG. 71 illustrates a configuration in which a plurality of insertion elements 1200a, b can be utilized. Each insertion element 1200a, b may include respective proximal end portions 1216a, b and distal end portions 1218a, b. Each shaft 1202a, b may extend between the proximal end portions 1216a, b and the distal end portions 1218a, b. The distal end portions 1218a, b may include respective tips 1220a, b of the insertion elements 1200a, b.

[0316] The needle hub 1222 may connect both proximal end portions 1216a, b to each other. The shafts 1202a, b of each insertion element 1200a, b may extend from the proximal end portions 1216a, b to the respective tips 1220a, b. The shafts 1202a, b may be separated from each other along the length of the shafts 1202a, b and may not be connected to each other by the material comprising the shafts 1202a, b. Thus, the shafts 1202a, b may comprise independent columns or pillars that extend parallel to each other and are joined at the needle hub 1222. The shafts 1202a, b may be overmolded at the needle hub 1222. The respective tips 1220a, b may not be connected to each other. The shafts 1202a, b may include free shafts that flex freely and independently of each other.

[0317] The shafts 1202a, b of each insertion element 1200a, b may be positioned on the boundary side surfaces of the elongated analyte sensor 956. For example, referring to FIG. 72, each shaft 1202a, b may be positioned on respective opposite sides 1224a, b of the elongated analyte sensor 956. The shafts 1202a, b and the elongated analyte sensor 956 may be arranged in a triangular configuration, although other configurations may be utilized as desired. The elongated analyte sensor 956 may be positioned between the shafts 1202a, b of each insertion element 1200a, b as shown in FIG. 72, and the central axis 1206 is laterally offset from a plane or line extending between the central axes 1204a, b. Other configurations may be utilized as desired (e.g., the central axis 1206 may be aligned with a plane or line extending between the central axes 1204a, b in a co-linear arrangement among other configurations).

[0318] The shafts 1202a, b of the respective insertion elements 1200a, b can be configured to support the elongated analyte sensor 956 upon insertion into the recipient's skin. The shafts 1202a, b of the respective insertion elements 1200a, b can be configured to support the elongated analyte sensor 956 in a deployed configuration such as that depicted in FIG. 71, for example. The deployed configuration can include a configuration in which the elongated analyte sensor 956 is positioned therein for deployment onto the recipient's skin. The elongated analyte sensor 956 can be positioned in the deployed configuration immediately prior to insertion into the recipient's skin and / or at another time prior to insertion (e.g., at the time of sterilization of the insertion elements 1200a, b and / or the elongated analyte sensor 956, as desired).

[0319] The outer surfaces 1208a, b of the shafts 1202a, b can contact the outer surface 1210 of the elongated analyte sensor 956 in the deployed configuration. For example, during a sterilization procedure or prior to insertion, the outer surfaces 1208a, b can contact the outer surface 1210 of the elongated analyte sensor 956 in an arrangement such as that shown in FIGS. 71 and 72. In an embodiment, the outer surfaces 1208a, b can be spaced apart from the outer surface 1210 of the elongated analyte sensor 956 in the deployed configuration. In an embodiment, one or more of the insertion elements 1200a, b or the elongated analyte sensor 956 can pass through a partition 1225 that can support the position of the elongated analyte sensor 956 relative to the insertion elements 1200a, b. For example, FIG. 73 illustrates a configuration in which the insertion elements 1200a, b and the elongated analyte sensor 956 axially pass through a partition 1225 that laterally stabilizes the elongated analyte sensor 956 relative to the insertion elements 1200a, b. The partition 1225 can be connected to the housing such that the elongated analyte sensor 956 extends therefrom, or can have another location (e.g., positioned on a patch or liner of the patch of the housing, as desired). In an embodiment, the use of the partition 1225 can be excluded.

[0320] The position of the elongated analyte sensor 956 external to the shafts 1202a, b of each of the insertion elements 1200a, b can provide various advantages. For example, in a sterilization procedure, the reduced contact surface area between the elongated analyte sensor 956 and the shafts 1202a, b can reduce the strength of any static friction that may form between the elongated analyte sensor 956 and the shafts 1202a, b. This can be static friction formed due to the expansion of the elongated analyte sensor 956 during sterilization that facilitates hydrogen bonding or formed by other causes. Additionally, the expansion of the elongated analyte sensor 956 within the interior of the insertion element (e.g., within the channels as represented in FIG. 28) can generate a large contact surface area between the outer surface of the elongated analyte sensor 956 and the inner surface of the insertion element due to the position of the elongated analyte sensor 956 within the insertion element. This large contact surface area can generate greater friction (both static and kinetic) between the insertion element and the analyte sensor 956. Positioning the analyte sensor 956 external to the shaft can reduce the surface area and friction (static and kinetic). For example, the longitudinally extending segments 1212a, b can include a surface area for contact that is smaller than the inner surface of the channel of the insertion element. The reduced friction can result whether or not the sterilization process is performed.

[0321] The insertion elements 1200a, b can also provide a smaller penetration profile for insertion into the skin than the insertion element that holds the analyte sensor 956 therein. Reduced wound size and impact can result.

[0322] The elongated insertion elements 1200a, b can guide the elongated analyte sensor 956 into the skin of a recipient in the configuration as shown in FIG. 71. The insertion elements 1200a, b and the elongated analyte sensor 956 can be inserted distally into the skin together. For example, FIG. 74 illustrates the insertion elements 1200a, b and the elongated analyte sensor 956 penetrating axially together into the skin 1227. The insertion elements 1200a, b can retract from the insertion site, leaving the elongated analyte sensor 956 inserted into the skin 1227, as represented, for example, in FIG. 75. The scale and size of the relative components can be different from the representations in FIGS. 74 and 75.

[0323] In an embodiment, the space 1226 (marked in FIG. 72) between the elongated insertion elements 1200a, b can include a fracture region where the skin 1227 is torn by the insertion elements 1200a, b to insert the elongated analyte sensor 956. The outer surfaces 1208a, b of the shafts 1202a, b can be laterally spaced apart from each other to create the space 1226, as desired. In an embodiment, variations can be provided. For example, FIG. 76 illustrates a variation where the outer surfaces 1208a, b are in contact with each other. The elongated insertion elements 1200a, b can create a fracture in an embodiment through which the elongated analyte sensor 956 can slide in.

[0324] Various other spacings can be utilized. FIG. 77, for example, illustrates an embodiment where a spacing 1228 smaller than the spacing shown in FIG. 72 can be utilized. FIG. 78 illustrates an embodiment where a spacing 1230 larger than that shown in FIG. 77 can be utilized. The spacing can be set in an embodiment to create a desired fracture region size.

[0325] In an embodiment, the number of insertion elements utilized can vary. One or more insertion elements can be utilized in an embodiment. For example, FIG. 79 illustrates a configuration in which three elongated insertion elements 1232a, b, c can be utilized. The insertion elements 1232a, b, c can be positioned in a triangular arrangement along with an elongated analyte sensor 956 coupled by the insertion elements 1232a, b, c. In an embodiment, only one insertion element can be utilized. In an embodiment, two or more insertion elements can be utilized.

[0326] In an embodiment, the size or diameter of the insertion elements utilized can vary. The insertion elements 1232a, b, c can each have, for example, a diameter smaller than each of the respective ones of the insertion elements 1200a, b. The insertion elements 1232a, b, c can each have a diameter smaller than the elongated analyte sensor 956. The insertion elements 1232a, b, c can be configured similarly to the insertion elements 1200a, b in other respects.

[0327] In an embodiment, the shape of the insertion elements can vary. For example, FIG. 80 illustrates a configuration of insertion elements 1234a, b each having an elliptical cross-section. The elliptical cross-section can vary the size or shape of a segment extending in the longitudinal direction of each of the respective insertion elements 1234a, b that can face the elongated analyte sensor 956. The insertion elements 1234a, b can alternatively be configured similarly to the insertion elements 1200a, b. The insertion elements can have, in an embodiment, a circular cross-section (as shown in FIG. 72). Other shapes can be utilized in an embodiment. The shape of the elongated sensor 956 can vary, for example, to produce an ellipse as shown in FIGS. 76 - 80. In an embodiment, a circular shape (such as that shown in FIG. 72) can be utilized among other shapes.

[0328] In an embodiment, two or more analyte sensors can be utilized. FIGS. 81 - 85 illustrate embodiments in which multiple analyte sensors can be utilized. The features of FIGS. 71 - 80 or any other embodiment herein can be utilized in conjunction with the embodiments of FIGS. 81 - 85.

[0329] FIG. 81 illustrates an example in which a second analyte sensor 956b can be used in combination with a first analyte sensor 956a. The second analyte sensor 956b can be positioned on the opposite side of the elongated insertion elements 1200a, b from the first analyte sensor 956a. The analyte sensors 956a, b and the elongated insertion elements 1200a, b can be positioned in a diamond configuration. Other configurations (e.g., rectangular or collinear) can be utilized in embodiments.

[0330] The elongated insertion elements 1200a, b can separate and isolate the first analyte sensor 956a from the second analyte sensor 956b. Thus, during the sterilization process, a reduced likelihood of the first analyte sensor 956a having static friction in contact with the second analyte sensor 956b can result. Such a configuration is different from a configuration in which multiple analyte sensors can be inserted into a single channel (having a representative channel shown in FIG. 28). The sterilization process can result in static friction between multiple analyte sensors within a single channel. The elongated insertion elements 1200a, b can separate and isolate the first analyte sensor 956a from the second analyte sensor 956b to reduce the likelihood of such static friction. The elongated insertion elements 1200a, b can function to guide the analyte sensors 956a, b into the recipient's skin in a manner similar to that discussed with respect to FIGS. 71-80.

[0331] In an embodiment, the lateral spacing between the elongated insertion elements 1200a, b can be varied to vary the size or shape of the space 1236 between the elongated insertion elements 1200a, b. As represented in FIG. 83, a lateral spacing 1238 between the elongated insertion elements 1200a, b that is greater than the space 1236 shown in FIG. 82 can reduce the lateral distance between the analyte sensors 956a, b. The size or shape of the space 1236 can be varied as desired.

[0332] The number of analyte sensors can be varied as desired. For example, FIG. 84 illustrates four analyte sensors 956a, b, c, d that are being utilized. The elongated insertion element 1200a may comprise a central elongated insertion element 1200a between the elongated insertion elements 1200b, c and the four analyte sensors 956a, b, c, d. The elongated insertion element 1200a may divide and separate the four analyte sensors 956a, b, c, d from each other.

[0333] The elongated insertion elements 1200a, b, c may be positioned collinearly with each other, and each analyte sensor 956a, b, c, d is coupled by two of the elongated insertion elements (analyte sensor 956a is coupled by elongated insertion elements 1200a, b, analyte sensor 956b is coupled by elongated insertion elements 1200a, b on the side opposite analyte sensor 956a, analyte sensor 956c is coupled by elongated insertion elements 1200a, c, and analyte sensor 956d is coupled by elongated insertion elements 1200a, c on the side opposite analyte sensor 956c). The insertion element 1200c may alternatively be configured similarly to the insertion elements 1200a, b, and the analyte sensors 956a, b, c, d may alternatively be configured similarly to the analyte sensor 956.

[0334] In embodiments, more or fewer numbers of analyte sensors and elongated insertion elements may be utilized. In embodiments, the shape or size of the analyte sensors and elongated insertion elements may be varied. The positions of one or more of the analyte sensors or elongated insertion elements may be varied relative to each other.

[0335] For example, FIG. 85 illustrates five elongated insertion elements 1240a, b, c, d, e that are utilized to divide and separate three analyte sensors 956e, f, g. Each of the insertion elements 1240a, b, c, d, e may have a diameter smaller than each of the analyte sensors 956e, f, g. The insertion elements 1240a, b, c, d, e may be arranged in an alternating orientation. The analyte sensors 956e, f, g may be arranged in an alternating orientation. Analyte sensor 956e may be coupled by insertion elements 1240a, b, c. Analyte sensor 956f may be coupled by insertion elements 1240b, c, d. Analyte sensor 956g may be coupled by insertion elements 1240c, d, e. Various other configurations may be utilized as desired. The insertion elements 1240a, b, c, d, e may alternatively be configured similarly to insertion elements 1200a, b, and the analyte sensors 956e, f, g may alternatively be configured similarly to analyte sensor 956.

[0336] FIG. 86 illustrates an embodiment including a distal tip 1244 configured such that an elongated insertion element 1242 extends radially (e.g., laterally as shown in FIG. 86) over at least a portion of a distal tip 1246 of an elongated analyte sensor 956. FIG. 87 illustrates a perspective view of distal tip 1244 or a proximal surface 1248 of distal tip 1244 extending over distal tip 1246 of elongated analyte sensor 956.

[0337] The distal tip 1244 may project radially outwardly so as to have a diameter 1250 larger than a diameter 1252 of a shaft 1254 of the elongated insertion element 1242. The distal tip 1244 may extend radially over at least a portion of the distal tip 1246 of the elongated analyte sensor 956 to shield the distal tip 1246 of the elongated analyte sensor 956 during penetration into the recipient's skin. Accordingly, the distal tip 1244 may create a distal fracture region of the elongated analyte sensor 956 into which the elongated analyte sensor 956 may be inserted.

[0338] The elongate insertion element 1242 can be configured to rotate to displace the distal tip 1244 of the elongate insertion element 1242 from the distal tip 1246 of the elongate analyte sensor 956 upon retraction of the elongate insertion element 1242. For example, a rotation mechanism 1256 can be provided that rotates the elongate insertion element 1242 and the distal tip 1244 to expose a portion of the distal tip 1246 of the elongate analyte sensor 956.

[0339] The rotation mechanism 1256 can have various configurations in embodiments. For example, FIG. 86 illustrates a helical thread 1258 that can be engaged by a protrusion 1260. The helical thread 1258 can be positioned on the needle hub 1262 or at another location as desired. The protrusion 1260 can be positioned on an applicator system for a skin-wearable medical device or at another location as desired. When the elongate insertion element 1242 is retracted, the rotation mechanism 1256 can generate rotation of the distal tip 1244 of the elongate insertion element 1242 to expose a portion of the distal tip 1246. Other configurations of the rotation mechanism 1256 can be utilized as desired (e.g., among other things, gears, cams, levers, electrically actuated).

[0340] Rotation of the distal tip 1244 can occur within the skin 1227. For example, FIG. 88 illustrates an elongate insertion element 1242 that penetrates the skin 1227 and rotates within the skin 1227. The distal tip 1244 rotates (e.g., by 180 degrees or another amount) to expose the distal tip 1246 of the elongate analyte sensor 956. Thus, the distal tip 1244 and the elongate insertion element 1242 can be retracted from the skin 1227 with the elongate analyte sensor 956 remaining in a predetermined position.

[0341] Alternatively, the elongate insertion element 1242 can be configured similarly to the insertion element 1200a or any other form of the insertion element disclosed herein.

[0342] The elongate insertion element can include a needle or can have any other form as desired.

[0343] The features of the embodiments disclosed in this specification can be used alone or in combination with any system, apparatus, or method disclosed herein.

[0344] The foregoing description sets forth the best mode contemplated for carrying out and making and using the invention in terms that will enable the relevant art practitioner to make and use the invention in complete, clear, concise, and exact terms. However, the invention is subject to modifications and alternative configurations from that considered to be fully equivalent. As a result, the invention is not limited to the specific embodiments disclosed. In contrast, the invention encompasses all modifications and alternative configurations that fall within the spirit and scope of the invention as generally represented by the following claims, which particularly point out and distinctly claim the subject matter of the invention. Although the present disclosure has been illustrated and described in detail in the drawings and foregoing specification, such illustration and description are to be considered illustrative or exemplary and not restrictive.

[0345] All references cited herein are hereby incorporated by reference in their entirety. To the extent that the incorporated publications and patents or patent applications conflict with the disclosure contained herein, the present specification is intended to supersede and / or take precedence over any such conflicting material.

[0346] Unless otherwise defined, all terms (including technical and scientific terms) may be to be given their ordinary and customary meaning to those of ordinary skill in the art and should not be limited to special or customized meanings unless explicitly defined as such herein. It should be noted that the use of a particular term when describing a particular feature or aspect of the present disclosure should not be construed as implying that the term is redefined herein to include any specific characteristics of the feature or aspect of the present disclosure to which the term is associated. The terms and phrases used in this application, and variations thereof, should be construed as open-ended rather than limiting, unless otherwise explicitly stated, particularly in the appended claims. As an example of the foregoing, the term "comprising" should be read to mean "including without limitation", "including but not limited to", etc. The term "comprising" as used herein is synonymous with "including", "containing", or "characterized by", and is inclusive or open-ended and does not exclude additional unrecited elements or method steps. The term "having" should be construed to mean "having at least". The term "including" should be construed to mean "including but not limited to".The term "example" is used to provide an illustrative instance of the item under consideration, not an exhaustive or limiting list thereof. Adjectives such as "known", "normal", "standard", and terms of similar meaning should not be construed as limiting the item described to that available at a given period or point in time, but rather should be read to encompass known, normal, or standard techniques that are or may be available at any present or future time. Terms such as "preferably", "preferred", "desired", or "desirable" and words of similar meaning are not intended to imply that a particular feature is important, essential, or even more important to the structure or function of the invention, but rather are simply intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment. Similarly, a group of items joined by the conjunction "and" should not be read as requiring that each and every one of these items be present in the group, but rather, unless expressly stated otherwise, should be read as "and / or". Similarly, a group of items joined by the conjunction "or" should not be read as requiring mutual exclusivity within the group, but rather, unless expressly stated otherwise, should be read as "and / or".

[0347] Where a range of values is provided, it is understood that the upper and lower limits thereof, as well as each intervening value therebetween, are included within the examples.

[0348] Regarding the use of substantially any plural and / or singular terms in this specification, those skilled in the art can interpret from plural to singular and / or from singular to plural as appropriate for the context and / or application. For clarity, various singular / plural substitutions may be explicitly described in this specification. The indefinite article "a" or "an" does not exclude the plural form. A single processor or other unit may achieve the functions of multiple matters recited in the claims. The mere fact that certain means are recited in mutually different dependent claims does not indicate that a combination of these means cannot be used to obtain an advantage. The reference signs in the claims should not be construed as limiting the scope.

[0349] If a specific number is intended in the recitation of a claim being introduced, such intent will be explicitly recited in the claim, and in the absence of such recitation, it will be further understood by those skilled in the art that no such intent exists. For example, for purposes of illustration, the following appended claims may include the use of introductory phrases “at least one” and “one or more” to introduce a recitation of a claim. However, the use of such phrases should not be construed as suggesting that introducing the claim recitation by the indefinite article “a” or “an” limits any particular claim that includes the recited claim to embodiments that include only one such recitation, and this holds even when the introductory phrases “one or more” or “at least one” and the indefinite article, such as “a” or “an”, are included in the same claim (e.g., “a” and / or “an” should normally be construed to mean “at least one” or “one or more”). The same holds for the use of the definite article used to introduce a recitation of a claim. Additionally, even when a specific number of the introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be construed to mean at least that recited number (e.g., a mere recitation of “two recitations” without other modifying phrases typically means at least two recitations, or two or more recitations). Further, when conventional expressions similar to “at least one of A, B, and C” are used, generally such constructs are intended in the sense that those skilled in the art will understand such conventional expressions (e.g., “a system having at least one of A, B, and C” includes, but is not limited to, a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.).When conventional expressions similar to "at least one of A, B, or C, etc." are used, generally, such a structure is intended in the sense that one of ordinary skill in the art would understand such a conventional expression (for example, "a system having at least one of A, B, or C" includes, but is not limited to, a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, and C, etc.). One of ordinary skill in the art will further understand that any disjunctive words and / or phrases presenting two or more alternative terms, in fact, should be understood as contemplating the possibility of including one of those terms, any of those terms, or both terms, regardless of whether in the specification, the claims, or the drawings. For example, the phrase "A or B" is understood to include the possibilities of "A" or "B" or "A and B".

[0350] All numerical values representing amounts of raw materials, reaction conditions, and other similar things used in this specification should be understood to be modified in all cases by the term "about". Therefore, unless otherwise indicated, the numerical parameters described in this specification are approximate values that may vary depending on the desired properties sought to be obtained. At a minimum, rather than as an attempt to limit the application of the doctrine of equivalents to the scope of any claim in any application claiming priority to this application, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding techniques.

[0351] Furthermore, the above has been described in some detail by way of illustration and example for purposes of clarity and understanding, but it will be apparent to one of ordinary skill in the art that certain changes and modifications can be made. Therefore, the description and examples should not be construed as limiting the scope of the invention to the specific examples described herein, but rather, should be construed as covering all modifications and alternative examples that come with the true scope and spirit of the invention.

Claims

1. A medical device system, A housing configured to be attached to the skin of a recipient, comprising a distal surface facing the skin and a proximal surface facing the opposite side of the distal surface, An elongated analyte sensor is connected to the housing, extends distally from the housing, and is configured to be positioned within the skin of the recipient. A medical device system comprising an elongated insertion element, the elongated insertion element including a shaft that extends along a portion of the elongated analyte sensor and is configured to be inserted into the skin to guide the elongated analyte sensor into the skin of the recipient, the shaft including a surface configured to reduce friction with the portion of the elongated analyte sensor.

2. The medical device system according to claim 1, wherein the surface is configured to reduce static friction with the portion of the elongated analyte sensor.

3. The medical device system according to claim 1, wherein the surface includes a surface texture.

4. The medical device system according to claim 1, wherein the surface includes a surface roughness of 35-square-mean-square (RMS) microinches or more.

5. The medical device system according to claim 1, wherein the surface includes one or more of the following: bumps, holes, or grooves.

6. The medical device system according to claim 1, wherein the surface includes a coating configured to reduce friction with the portion of the elongated analyte sensor.

7. The medical device system according to claim 6, wherein the coating includes a lubricant.

8. The medical device system according to claim 6, wherein the coating comprises one or more of plating, immersion coating, or vapor deposition.

9. The medical device system according to claim 6, wherein the coating comprises a polymer.

10. The medical device system according to claim 6, wherein the coating includes a thermal oxide.

11. The medical device system according to claim 6, wherein the coating comprises an inert material.

12. The medical device system according to claim 6, wherein the coating is coupled to the shaft.

13. The medical device system according to claim 6, wherein the coating has a thickness of less than 1.5 micrometers on the shaft.

14. The medical device system according to claim 6, wherein the coating is cured.

15. The medical device system according to claim 6, wherein the coating comprises silicone.

16. The medical device system according to claim 15, wherein the silicone comprises an amino-functionalized dimethylsiloxane copolymer.

17. The medical device system according to claim 1, wherein the surface is configured to reduce hydrogen bonding with the portion of the elongated analyte sensor.

18. The medical device system according to claim 1, wherein the elongated insertion element includes a needle.

19. The medical device system according to claim 1, wherein the elongated insertion element includes a channel for receiving the portion of the elongated analyte sensor.

20. The medical device system according to claim 19, wherein the channel has a C-shaped cross-section.

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